Ill 11 nil PUBLICATIONS REFERENCE

fltS777

IMBSIR 75-942

The National Measurement

System for Optics

Dennis A. Swyt

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

Final

March 1976

Issued August 1976

^ 1. DEPARTMENT OF COMMERCE

,^ - ^ °NAL BUREAU OF STANDARDS

NBSIR 75-942

THE NATIONAL MEASUREMENT

SYSTEM FOR OPTICS

Dennis A. Swyt

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

Final

March 1976

Issued August 1976

U.S. DEPARTMENT OF COMMERCE, Elliot L. Richardson. Secretary

Edward O. Vetter, Under Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

CONTENTS

Page

EXECUTIVE SUMMARY . , , 1 1. INTRODUCTION 3 2. STRUCTURE OF THE MEASUREMENT SYSTEM 3 2.1 Conceptual System 3 2.2 Basic Technical Infrastructure 5 2.2.1 Documentary Specification System 5 2.2.1.1 Standardization Institutions 5 2.2.1.2 Survey of Documentary Standards g 2.2.2 Instrumentation System 5 2.2.2.1 Measurement Tools and Techniques g 2.2.2.2 The Instrumentation Industry g 2.2.3 Reference Data 9 2.2.4 Reference Material . o 2.2.5 Science and People 11 2.3 Realized Measurement Capabilities ... 12 2.4 Dissemination and Enforcement Network , , 15

2.4.1 Central Standards Authorities 15

2.4.2 State and Local Offices of Weights and Measures 15

2.4.3 Standards and Testing Laboratories and Services 15

2.4.4 Regulatory Agencies ..... 15

2.5 Direct Measurement Transactions Matrix ... 17 2.5.1 Analysis of Suppliers and Users 17 2.5.2 Highlights Regarding Major Users 22

3. IMPACT, STATUS AND TRENDS OF MEASUREMENT SYSTEM 24

3.1 Impact of Measurements ..... 24

3.1.1 Functional, Technological and Scientific Applications 24

3.1.2 Economic Impacts -- Costs and Benefits 24

3.1.3 Social, Human, Person-on-the-street Impacts 26

3.2 Status and Trends of the System 27

4. SURVEY OF NBS SERVICES 29

4.1 The Past 29

4.2 The Present -- Scope of NBS Services 29

4.2.1 Description of NBS Services 29

4.2.2 Users of NBS Services 31

4.2.3 Alternate Sources 34

4.2.4 Funding Sources for NBS Services 34

4.2.5 Mechanism for Supplying Services 34

4.3 Impact of NBS Services 35

4.3.1 Economic Impact of Major Users Classes 35

4.3.2 Technological Impact of Services 38

4.3.3 Pay-off from Changes in NBS Services 38

4.4 Evaluation of NBS Program 39

4.5 The Future 40

5. SUMMARY AND CONCLUSIONS 41

Appendix A. METHODOLOGY OF THE STUDY 43

Appendix B. BIBLIOGRAPHY 43

i
Figure 1;

Figure 2:

Figure 3;

Figure 4:

Figure 5:

Figure 6;

Figure 7;

Table 1:

Table 2:

Table 3:

Table 4:

Table 5:

Table 6:

Table 7:

Table 8:

Table 9:

Table 10:

Table 11:

Table 12:

Table 13:

Table 14:

Table 15:

LIST OF FIGURES

Page

Photographic grey scale 4

Modulation transfer function of "good" and "bad" lenses 5

Basic pattern of the ANSI PH2.33 resolving power target 10

The NBS microcopy resolution chart H

Spatial frequency ranges of sensitized photographic materials ... 13

NBS and the measurement system 36

Input-Output chart of NBS programs in optics • • 37

LIST OF TABLES

Direct measurements transaction matrix 1^

Interaction matrix suppliers and users: SIC codes of non- government entries 19

1972 shipments of non-ophthalmic and non-photographic lenses

and lens instruments 20

Author's composite of the industrial and medical radiographic

measurement systems of 1970 25

Profile of hypothetical steel foundry 25

Cost of a single "traceable" measurement at a hypothetical

steel foundry 26

Estimated cost of medical x-rays for 1970 • 27

Approximate values of shipments of some optical & photographic equipment . 28

Effect of the semi -automation of the examination of chest

x-rays 29

Users of NBS photographic density standards 32

NBS standards by kind supplied to the major manufacturers of

basic photographic products 32

Users of NBS photographic density standards involved in the

production of strategic and tactical missile systems 33

Profiles of the measurement operations of some NBS density

standards users 34

NBS revenues in FY-1973 from fixed-fee services 35

Cost-to-NBS basis for sales price of photographic standards

in FY-1973 35

ii
The National Measurement System for Optics

Dennis A

National Bureau

Mechanics

EXECUTIVE SUMMARY

Measurements in imaging optics are fundamental to the manufacture of products ranging from spectacles, microscopes, photographic goods and microfilmed documents to aircraft, nuclear reactors and oil pipelines;

the measurement quantities of interest are "diffuse visual density" which characterizes

the darkness of photographic, radiographic

and ink-on-paper images; and numerous measures of optical system performance (refractive power, resolution, optical transfer

functions, etc). Diffuse visual density is

defined by American National Standards In- stitute documentary standards; many voluntary standards and federal specifications

relate to its application. Measures of

optical system performance are in general

undefined by documentary standards.

The measurements are most intimately re- lated to the output of the photographic and

optical industries. In figures characteristic of years in the early 1970's, these

goods included $1.3 billion worth of sensitized photographic goods, $4 billion in

photographic products and $485 million in

lenses and optical instruments. Typical

sales of $5 million in densitometers and $35

million in non-ophthalmic test equipment provide some means of indication.

Some of the measurements are performed by:

*18,000 eye examiners and 20,000 dispensers

of lenses supplying 100 million wearers of

corrective lenses with ophthalmic lenses

costing $190 million in a $2 billion system of eye care *10,000 medical radiologists, supported by

90,000 technicians, examining an estimated

325 million x-rays of 110 million patients

at an estimated cost of $4 billion

*15,000 industrial radiographers performing

an estimated 45-90 million measurements in over 6300 plants at an estimated cost of

$350 million. Typical data for products

affected by these measurements are $7.6

billion in aircraft production, $4.6 billion in missiles and space hardware, the

$64 billion in nuclear reactors con- tracted for in the period 1965-73, and

the $600 million of pipelines constracted

annually.

NBS contributes to the operation of the

measurements system by providing diffuse visual density standards, microcopy resolution

. Swyt

of Standards

Division

charts and an optical system and lens evaluation service. The density standards are

used by, among others, the eleven companies

which accounted for virtually 100% of photo

film sales and 80% of equipment sales in

1970: the standards are required by clearcut AEG, NASA, and DOD specifications, by an ambiguously worded FAA requirement, with a DOT standard for pipeline inspections that

trails off into an oil industry standards.

The NBS Microcopy Resolution Chart is a voluntary standard for the $450 million microfilm industry and a mandatory standard for

use in DOD microfilming operations; the NBS

chart is on the verge of formal acceptance

as an international standard. The lens

testing services have primarily benefitted

federal agencies.

In eighteen month period in which outputs

of NBS were evaluated, a program which in

1973 consisted of 3 1/2 man-years of effort

with a $319,000 budget (of which $118,000

was from other federal agencies) provided

15,000 microcopy charts, 200 density standards, 10 interferometers for an AEC prime

contractor, a handful of lens tests, a number

of special studies for federal agencies, a significant amount of testing and consultation on optical systems for security-classified federal agencies, as well as major

publications on the theory and operation of

advanced optical systems.

The primary result of this study of the

measurement system has been to reveal the

nature of the users of NBS services and the

degree of their dependency on the standards

NBS supplies. Incremental analysis, the

tracing of the economic effect of NBS ser- vices through causal chains to final products and services, has not proven feasible.

Recommendations regarding NBS programs

are to upgrade density measurement capabilities, to maintain without further ex- pansionary investment the lens testing ser- vices, and to channel the image analysis

measurements toward optics-related measurement problems. Discontinuation of NBS ser- vices in this field-, it is thought, would

result in the provision of the same services by one or more other federal agencies.

Continuation of the study of the measurement

system might involve assessments of the desi reability of NBS reference standards of

1
reflection density and of the interest of

optical manufacturers in a round-robin approach to measurement assurance in lens

testing.

Documentary data and informed opinion for

this study have been acquired by means of a survey questionnaire to 150 users of calibration services; canvassing letters to 30

instrument manufacturers, 25 trade and industrial associations, and 50 optical comr panies; personal interviews with 30 individuals at organizations throughout the

country; innumerable telephone contacts; as well as direct use of documentary and

library source materials.

2
1. INTRODUCTION

From the earliest times man has sought

to extend the limited range of his vision

and to communicate what he had seen. First

with simple magnifiers, later with telescopes and microscopes, he examined the

small world within reach and the great

world at a distance; but he could convey

in words and drawings only a part of what

had been observed.

Then in 1839, an artist named Daguerre

held an exhibition in the salon of the

French Academy. He revealed the results of

a process he had developed to permanently

record images produced by lenses. The

event marked the opening of the era in which

men could show others in graphically realistic detail what they had seen. Separately and in combination, film and

lens revolutionized human affairs, science,

medicine. Within decades, Europe's populace saw in photographs the carnage of the

Crimean war; Madame Curie named radium the

element which had fogged some sensitized

photographic plates; and physicians based

diagnoses on the images of internal organs

appearing in x-ray radiographs.

Today the excitement of these events is long in the past but the benefits continue.

To illustrate the ways in which lenses and

photographic materials affect us, imagine

yourself to be a traveller at an air ter- minal with a long layover. Imagine yourself

mentally labelling with red tags the products

and services which are based on optical,

photographic and radiographic processes.

Start off easily. Tag every lens you see: tourists' cameras, binoculars, passengers'

eyeglasses, the security television camera. Mark every photograph: advertising displays, magazine covers, ID badges, the

snapshots in your wallet. Put one on everything that has information stored on microfilm: the car rental agency, the

insurance desk, the airline company, the

New York Times; put a few in your pocket

for driver's license, library card, auto

registration, and credit cards. Tag the

weather report; it's based on satellite

photographs of cloud formations. Stick

tags on things that had film x-rays taken

of them: the chests of pilot, crew and

food service v/orkers, all those teeth and

arms and legs and things of people around;

the aircraft itself gets a handful for airframe, turbines, pumps, landing gear. Paste

the tags on anything with integrated circuit

devices (they're photofabricated) : the

radar, tower communications systems, the or- dinary radio and television sets. Since

nuclear reactors, steam turbines, refinery

equipment and transmission pipelines are

radiographically inspected, tag just about

everything that runs on electricity or oil. Now imagine the number of red tags around

you.

Along the complex chain which links a manufacturer to you, all the red-tagged

items required measurements on images.

These measurements are means to give

objective answers to questions such as:

Is the image sharp? Is it too dark or light? Are fine details visible? Have

the shapes of objects been reproduced

faithfully? Is the contrast good? In essence, these measurements seek to tell how well a lens system makes an image or how well a medium records it.

This report in turn is an attempt to answer some questions about the measurements themselves. What are they, who

makes them, where, why, at what cost,

to whose benefit, what role does the

National Bureau of Standards play? The answers are by necessity incomplete but,

hopefully, informative nonetheless.

2. STRUCTURE OF THE MEASUREMENT SYSTEM

2.1 Conceptual System

To familiarize oneself with the important

measurements of image optics, one might follow in thought the construction and testing

of a rudimentary camera.

First, surfaces with the same curvature

are ground onto opposite faces of a glass

disc. After polishing the surfaces, one measures their radius of curvature and

the overall lens diameter. Using a textbook formula, measured radii of curvature,

and the index of refraction of the lens

material , one computes the foaal length,

the distance from the lens at which will

be formed the image of small, greatly

distant source of light. Focal length is also measured directly by the same prescription. The reciprocal of the focal

length is the di optic pov/er or refractive

power of this simple lens.

The body of the camera consists of an oilcloth bellows, closed at one end by a ground glass screen and at the other by a plate with a hole into which is mounted the

lens. On the wall of the workshop hangs an illuminated target. The device is rested on

a tripod, aimed, the bellov/s length adjusted

until a sharp image of the target is focussed

on the glass and the bellows locked in place.

The image on the glass is like the har

test target on the wall, consisting of pat- terns of bars, dark on light background,

with progressively smaller widths and

spacings. However, the focussed image has

distortion; it is different in shape than the

3
target, due to lens aberrations. One may also

notice that, in all the patterns smaller than

a certain one, the lines are indistinguishable; they may lie below the resolution limit of the lens

Up to this point, measurements have been

dimensional. Radius of curvature and focal

length are given in millimeters and resolution limit in lines per millimeter. At this

point more sophisticated tests begin. The

bar test target is replaced by a sinewave

target in which the variations from dark to light to dark in each pattern are not

abrupt but gradual . The reciprocal of the

distance between successive dark or light

bands is the spatial frequency of the pattern

(also loosely given in lines per millimeter

rather than cycles per millimeter).

The technique is to determine how well

the image of the target reproduces for many

spatial frequencies the difference in the

brightness of the dark and light bands (the

contrast or modulation); also to determine

if the lens causes a band to be in a different position than if the lens were removed

and the band projected through the lensmounting aperture directly onto the

ground glass. The difference in these two positions is the spatial phase introduced

by the lens. The modulation and spatial

phase may be determined by measuring the light

intensity at different positions in the image

or recording the image on film and analyzing

that; the latter case will be illustrated.

To the camera is added a bladed shutter

which will open to let light enter only for

brief periods and the ground glass replaced

with film; a series of pictures is taken of

the target with the shutter open for progressively longer periods and the film re- moved and developed. The images on the film

reveal much about the lens and the film.

The first picture is completely clear,

not enough light has entered the camera for

an image to register. The last picture is

completely black, so much light has entered

that the film is completely exposed. The

pictures in between have images in progressively darker shades of grey. The measure of the degree of darkening of the

film is the optical density. To actually measure the optical density, one would measure the amount of light which strikes

the film and the amount which passes

through and do a calculation of density, D:

n

- Inn light transmitted

^ ~ "'°9io light incident

However, one may assess the optical densities of the images by comparing them,

either by eye or machine, to a photographic

step tablet (also called a grey scale or a

Figure 1. A photograhic density grey scale

density wedge). This is a piece of film with

exposed and developed strips of grey for which

the optical densities have been measured

(Figure 1).

If the density of each image at the same relative position in each picture is determined and this information combined with the

times the shutter was open, a graph can be

drawn: density versus the logarithm of the

relative amount of light reaching the film.

This graph is like a D-log E curve (or H and

D curve, for Hurter and Driffield) except it

has relative amounts of light not the absolute amounts. From the D-log E curve come

the definitions of the film speed (the

minimum exposure needed to produce a certain

density), the film contrast (a measure of

how density increases with exposure), and

other properties like these which describe

film response to either light or x-rays.

In order to measure the lens response,

the test chart was imaged onto the ground

glass; photographing the image introduced

4
the film response but information derived

from the D-log E curve allows that effect to

be subtracted off. Therefore, if the modulation (contrast) on the film is measured

for a number of different spatial frequencies and the effects of the contrast of the

original target and the film response taken

into account, a plot of the modulation introduced by the lens versus spatial frequency (the modulation transfer function, MTF)

may be made. If the spatial phases are measured and added to this plot, the result

is the optical transfer function of the lens

(Figure 2).

Two more tests which are often performed

on lenses and film are: a target essentially

consisting of a broad black bar on a white

field is photographed and the density of the

image in the neighborhood of the sharp boundary between the light and dark areas is

measured to get an edge trace; and a small

point of light is photographed and the density variations along the diameter of the

image measured for the point spread function.

SPATIAL FREQUENCY (cyclct/mm)

Figure 2. Modulation transfer functions of

"good" and "bad" lenses

The conceptual exercise of following the

construction and testing of a simple camera

has served as a means of introduction to some of the measurements associated with

lenses and film. These measurements are a means to answer the questions asked rhetorically in the Introduction. In summary, some

of the measurements for a lens are: radius

of curvature, focal length, refractive

power, resolution limit, aberrations, distortion, modulation transfer function, optical transfer function, edge trace and point

spread function; for the film: optical density, speed, contrast, resolution limit,

and the same four last items as the lens.

These are some of the measurements which are

the "what" of imaging optics. In the next

two sections will be described some of the

"how".

2.2 Basic Technical Infrastructure

2.2.1 Documentary Specification System

2.2.1.1 Standardization Institutions

In the U.S., standardization (that process by which goods are manufactured in

uniform size, quality, strengths, etc.) is

generally voluntary. Product standards

are issued by private groups and serve as quidelines to manufacturers, consumers, and

the general public. Except for health and

safety regulations and their own procurement specifications, federal, state and

local government bodies tend not to exercise

enforcement powers in matters of standardization.

The most important private standards

organization in the United States is the

American National Standards Institute

(ANSI). This federation of trade, technical,

professional, labor, consumer and government

organizations approves and coordinates voluntary standards. A documentary standard

issued by ANSI "implies a consensus of those

substantially concerned with its scope and

provisions." Some of the standards are of interest for this report.

In its role as coordinator of U.S. voluntary standards activities, ANSI is the U.S.

representative to the International Organization for Standards (ISO). This non- governmental group, founded to facilitate

trade, promulgates standards which, like

American National Standards, are not binding,

not even on members which approved the

documents.

Two other groups with something to say

about lenses or film are the National Microfilm Association which is a trade organization

in the micrographics industry and the

American Society of Mechanical Engineers, a professional organization. A trade group,

the Graoure Technical Association, supports

that particular type of printing industry.

There is a Department of Agriculture

specification for aerial mapping cameras but

nothing on image quality in itself. The

Federal Aviation Agency (concerned with air

safety). Department of Transportation (concerned with pipeline safety) and the

Nuclear Regulatory Agency (concerned with

nuclear reactor safety) all have requirements which involve film usage. The Department of Defense and the National Aeronautics

5
and Space Agency have similar requirements in

hardware procurement procedures

The federal General Services Administration

which handles procurement for the civilian

government and the Military Supply Service

which writes the specifications for the

Defense Department have numerous documents more or less relevant to this report.

2.2.1.2 Survey of Documentary Standards

The current catalogue issued by the American National Standards Institute indicates

that the group has standards for measuring

refractive power of opthalmic lenses; ANSI

Z80.1 for spectacle lenses and ANSI Z80.2 for

contact lenses. They both say use a "standard" instrument to do the measurement. ANSI

has standards for the screw threads of microscope objectives and the barrel markings of

photographic lenses; none on testing the

lenses. The National Microfilm Association

has two standards for determining the re- solution of microfilm systems: MS104 for

microfilm and MS5 for microfiche. These

standards refer to a domestically produced

test chart which satisfies the requirements

of an international draft standards, ISO DSI

3334, on microfilm resolution.

The standards for film and photographic

materials issue from ANSI. PH2.33 gives a method for determining the resolving power

of photographic materials. PH2.17 defines

optical density for reflection (like prints

have) and PH2.19 defines it for transmission (like negatives have). PH2.19

conforms to the international standard for

transmission density given in the document

IS05.

Based on the two ANSI standards for

optical density are those for determining

speed: PH2.2 for photographic paper, PH2.5

for negative materials, PH2.8 for industrial

x-ray film, PH2.9 for medical x-ray film and

PH6.1 for "intraoral" dental x-ray film.

PH2.5 is consistent with the international

standard for film speed, IS06. A spot survey of the federal specifications issued by the General Services Administration shows, not surprisingly, that this

group handles the office supplies and leaves

specification of technical systems to the

individual agencies which buy them; it has

standards on film but not lens sytems. The

omnibus Federal Standards No. 170 on photographic film references ANSI PH2.5 for

speed, PH2.19 for optical density, and

PH2.33 for resolving power. Federal

Specification L-F-333A on motion picture

film is based on FS No. 170. The specifications for x-ray film, FS L-F-310 on medical and dental and FS L-F-350 on industrial, are both tied to the older ANSI

PH2.8.

The military, as one would expect, have

standards and specifications on everything.

For optical products, from binoculars to gun sights to telescopes to cameras of every

kind, there are around 250. In general, the

relevant military specifications for film

ride along with the federal specifications.

The DOD has, however, some significant

standards dealing with microfilm. The

military specification which gives the basic

guidelines for testing microfilm systems is

MIL-M-9868D, 'Requirements for Microfilming

Engineering Documents'; MIL-M-38748 covers microfiche, MIL-P-9879 covers architectual

drawings, and Mil-M-38761 covers microfilm

of technical data. The basic standard for

resolution testing is consistent with the

National Microfilm Association standards;

the same test target is called for.

With respect to military standards on

optical systems, it should be kept in mind

that the Department of Defense procures

some rather sophisticated optics with

performance specifications that stretch

the state of the art of image quality

testing. Acceptance standards are of

necessity a matter of negotiation.

2.2.2 Instrumentation System

2.2.2.1 Measurement Tools and Techniques

In the mental exercise of following the

fabrication and testing of a simple box camera, the details of the principles involved

with the measurements, the instruments, and

the standards were not given. Before these

are covered, some of the relevant properties

of light will be reviewed for the convenience

of the reader. Light normally travels in

straight lines, but when it passes from one transparent medium (such as air) into a different transparent medium (such as glass)

it can bend (or refract). Light can be re- flected from surfaces such as mirrors or metals. Light may also be bent, or diffracted, as it passes the edge of an object.

When light from two different sources, even

two points on the same source, reaches some place at the same time, it can add together

or cancel out, that is, interfere. The principles of linear propogation, refraction,

and reflection form the core of the subdivision of optics called geometrical optics.

The principles of diffraction and interfer- ence are elements of physical optics. The

design of any optical system which uses the

focal properties of lenses requires knowledge of geometric optics; the design of es- pecially high performance optical devices re- quires a further knowledge of physical optics.

For simple optical lenses like ophthalmic

spectacles, refractive power measurements

6
are sufficient for the tasks of design and

quality control. The imperfections of the

images produced by such lenses can be made

less than the eye can detect by ascertaining

that the lens has the proper focal properties. The refractive power of lenses may be

computed from measured values of radii of

curvature or focal length, or they may be

determined by comparison with lenses of

known power. The standards are, therefore,

length scales or lenses; the chain of standards is a short one: from a basic unit of

length to the length scale to a standard

lens or the final lens itself. Precisions

along this chain can be of the order of fractions of a millimeter. Lens systems more

complicated than spectacles or contact lenses are designed according to the principles

of geometrical optics but require testing

which extends beyond the measurement of re- fractive power.

Because the functioning of complex devices cannot be predicted from a simple knowledge of their construction, performance

testing is used. One index of performance

is the amount of distortion caused by the

lens or lenses. The difference in shape of

the object and of the image produced by the

optical device can be measured by: either

comparing the image of a target to the target

itself; or by projecting a narrow beam of

light through the lens and locating the position of its focus. The first technique

involves the use of a standard, the target.

Both methods are based on mechanical measurements of position.

A second index of performance for an intermediate^performance lens system is resolution limit. (Resolving power, a measure

of the smallest details which can be distinguished, applies to lens and film.) The

standard for resolution testing is a bar

target, a chart with patterns of lines printed on it; it may be either a transparency or

an opaque. Usually, the target is photographed and the image on the film examined

with a microscope to determine the smallest

pattern in which the lines are unambiguously

distinguishable. Resolution limits of optical devices range from perhaps 20 cycles per

millimeter for a crude lens and over 1000

c/mm for special photographic films to near

2000 c/mm for a high-quality microscope.

Again, the chain of standards proceeds via

the unit of length from the manufacturer of

the chart to the end user in one step.

For the highest performance optical devices, measurements related to the predictability of function and to actual perfor- mance testing are made. At some point in

the evolutionary hierarchy of optical

systems, the lenses produced are so free of

material, manufacturing, and design defects,

that the extremely small-scale effects of

diffraction and interference serve to limit

the ultimate performance of the device. A

lens of this quality is called "diffractionlimited." The atmosphere in which these

devices are tested is rarefied. There are essentially no documentary standards which

offer guidance and no standard test objects.

Testing of state-of-the-art optical components is done on ad hoc bases, with reliance

placed on the skills and knowledge of people

using special measuring instruments.

For a type of optical density important

to imaging optics, and therefore to this

report, the situation is quite different.

Associated with this optical density,

specified as American National Standards

Institute Diffuse Visual Density Type

Vl-b, is a fully developed measurement

system. The ANSI definition of diffuse

visual density imposes geometric and

spectral conditions on the general definition of optical density:

D = -loa j-lglrt returned from object

^10 Light incident on object '

Diffuse visual transmission density

characterizes photographic negatives;

diffuse visual reflection density characterizes fDhotographic prints.

Discussions with those familiar with the

field, such as standards committee chairmen

and instrument producers, have lead to the

conclusion, affirmed by these sources,

that only three laboratories in the nation

have facilities for the fundamental measurement of diffuse transmission densities as defined by the current documentary standards. The basic devices are called "inverse

square bars"; the name derives from the

principle of operation in which the amount of

light which reaches the detector varies as the reciprocal of the square of the distance

between the source of light and the detector.

A complete apparatus consists of a track

with the light source at one end, the detector which slides along the track, and a length scale. The detector is a hollow

sphere with a hole directed at the source

of light and another hole which points to- ward a light meter. The recipe for the determination of the density of a sample of

film is: measure the source-to-detector distance, read the meter, cover the first hole

in the sphere with the film, move the detector dov/n the track until the meter reads the

initial value, and measure the new source- to-detector distance. The optical density of

the film sample is computed from the equation:

n - 9 Ton (first distance)

^ ~ '°9l0 (second distance)
Since the systems are built to conform to the detailed documentary specifications

pertaining to geometry and spectral characteristics, they provide fundamental mea- surements, or primary calibrations, of diffuse visual photographic density.

A primary calibration of a photographic

density step tablet is carried out by the

measurement of the density of each of its

"steps" according to the procedure described. Typically the range of densities which

can be measured on an inverse square bar apparatus is from 0 to just above 4. The precision of the measurements will be discussed

below in section 2.3.

The concept of optical density may also be

applied to reflection. The American National

Standards Institute, in its documentary

standard ANSI PH2.17, defines diffuse reflection density in a manner analogous to its

definition of transmission density. In this case, however, the "primary standard" of re- flection density is "freshly prepared magnesium oxide," a white powdery chemical which

has been packed into a wafer. The unsatisfactory nature of the documentary standard

and the reference material is common knowledge among people who require good measurements of reflection density. A densitometer

manufacturer reports that barium sulfate is

most often used as a reference. The chair- man of the ANSI committee which issued the

documentary standard has indicated that the

standard is being revised to give a more

precise definition of the measurement quantity and to bring it into conformity with

the present practice of using the more stable and dependable material, barium sulfate,

as a reference.

2.2.2.2 The Instrumentation Industry

Measurements of the various optical

Quantities being discussed in this report

(e.g., refractive power, MTF, resolution

limit and specific types of optical density)

are made with both commercially manufactured instruments and custom-fabricated

devices

There are three important types of spherometers, instruments for measuring the radius

of curvature of spherical lenses or mirror

surfaces. The first consists of a ring

which rests on the surface and a micrometer

plunger in the middle of the ring to measure

the sag or bulge of the surface in the plane

of the ring. The second one has three feet

instead of the ring but works the same way.

The manufacturer has put gauges in the devices

which read out directly in refractive power

and has calibrated them by measuring the

distance the plungers move. The third spherometer is a microscope which projects an image onto the surface to be measured. The

source image is seen sharply imaged if the

microscope is focussed on either the surface

itself or on the center of the curvature;

the distance between these two positions is

equal to the radius of curvature. These

devices are calibrated at the factory by

measuring the powers of the two lenses they

contain. The Optical Industry and Systems

Directory for 2975 lists four companies

which make spherometers. People who manufacture and dispense spectacle lenses use

them; a representative of an ophthalmic company reports that probably 13,000 spherometers are in use; they cost less than a few hundred dollars each. A lensometer is also an ophthalmic instrument and is used to measure the magnitude and

direction of the maximum and the minimum powers of spherical -and cylindrical -sur- face spectacle lens. The lens is placed

in a parallel beam of light between two other

lenses; viewed in an eyepiece, the image of

an X-shaped target is brought to a focus by

moving the target; the distance moved is proportional to the refractive power of the

spectacle lens. A handful of optical

companies manufacture lensometers (or focimeters or vertometers, as they are also

called). The same company representative

estimates that the number of lensometers in use is about 38,000; these are distributed

among 8,000 physicians specializing in the

eye, 20,000 licensed eye examiners, and the

10,000 or so dispensers or makers of

spectacle lenses.

Distortion measurements are often made

with non-commercial devices. One such device

consists of a bench for mounting a target,

the lens to be tested and either a screen with a light measuring device or a camera.

A second such apparatus might consist of

the same basic set-up with the target re- placed by a light source which swings in an arc centered at the lens. The light source is moved to determine where the

light which passes through the lens is

projected. There are variations on this

method but the principle is the same.

In any case, a reliable mechanical refer- ence is the basis for distortion measurements . The most frequently used instrument for

optical density measurements in photographic

applications is the densitometer. This

device has a built in light source, a detector, and a light meter. It measures the

amount of light reaching the detector, with

and without a sample in place, and electronically computes optical density from the

ratio. The newest densitometers may have

digital read-out and display densities in the

range 0 to 1 to three decimal places and

densities from 1 to 4 to two decimal places.

Densitometers are adjusted at the factory
to read optical densities properly; often

photographic step tablets are shipped with

instruments to allow periodic readjustment.

Instruments may be designed to con form to the ANSI documentary standard PH2.19,

"Diffuse Visual Transmission Density."

There are also reflection densitometers

which conform to the ANSI document PH2.17

on reflection density and operate in a manner analogous to transmission densitometers.

Written responses to requests for data

from the manufacturers of densitometers listed in the Optical Industry and Systems Directory and discussions with these sources

of information have supplemented the statisics obtainable from governmental agencies.

The U.S. Department of Commerce figures for

1972 show sales of densitometers and similar

devices of more than $4 million that year

and $6 million for 1971 (Current Industrial

Reports, MA-38B(72)-1) . Although this

Department of Commerce report shows only

four companies with shipments greater than

$100,000, about 30 companies yearly market

a total of over 1200 general or special

application densitometers or light measuring

devices useful in densitometry. Of these 30

firms, four dominate in supplying densitometers for photographic film applications,

six supply most devices for clinical uses, a dozen serve the graphic arts, and five or six

furnish the instruments for special imageanalysis applications called microdensitometers. The simpler densitometers for photographic and graphic arts work cost about $750;

for more critical work as in photographic

manufacturing and industrial radiography,

units range in price from $1000 to $5000.

Scanning densitometers used in clinical and

chemical analysis run from $5000 to $8000.

The basic scanning microdensitometer employed

in high precision image analysis might sell

for over $20,000; if it were automated by a computer for control and data handling, the

total cost might be three to five times as much.

Devices like MTF equipment and interferometers for assessing the performance of high

quality optical systems are made up of components: lenses, lamps, lasers, optical

benches, mirrors, gratings, prisms , modulators

,

detectors and related devices. The items,

sometimes packaged as modules, are often

bought separately. About ten companies sell

MTF systems in the U.S. A modular system for

measuring the MTF of a sighting device might

sell for $15,000; the modules for testing an enlarging lens might cost $20,000. A sales

representative reports that his firm has

marketed over one hundred of basic systems

like these world-wide; four other supersystems had gone for $100,000 each.

Department of Commerce data for 1972 from

the Current Industrial Report cited above

show sales of optical test equipment to be

about $35 million annually.

2.2.3 Reference Data - Not Applicable

2.2.4 Reference Materials

In imaging optics, there are two important types of objects used in measurements which, for want of a better term, can be classified in this report as reference materials; the physical objects

are resolution targets and photographic

density standards. In turn, there are two major types of resolution targets

and two general types of photographic

density standards. All are photographic

materials which are prepared in careful

but conventional ways.

The American National Standards Institute

document ANSI PH2.33 describes a resolution

target for use in the determination of the

resolving power of photographic materials.

The basic building block of the overall pattern consists of three bars of equal widths

and spacing (Figure 3). A target is fabricated, for example, by laying out on a white

background thirty-nine of the basic patterns

of different sizes. The size of each one

is chosen such that the spatial frequency

from one pattern to the next increases by

a factor of 1.12. When the complete

array of patterns has been laid out, it is photographed at a carefully selected reduction ratio. What had been black patterns

on a white background are reversed: clear

patterns on a generally black negative. If

the reduction ratio is chosen precisely,

the spatial frequencies on the transparency

will range as the ANSI document specifies

from 0.10 cycles per millimeter to 7.94 cycles per millimeter.

The second important resolution target

has five bars in the basic pattern rather

than three. The design for this target was developed in a government laboratory with

the testing of microfilm systems in mind.

In this case, 26 patterns of five bars of

equal widths and spacings are laid out on a white backgound. Again the ratio of spatial

frequencies between successive patterns is

1.12. The same process of reduction

photography described above is followed; how- ever, the reduction ratio is chosen to yield

patterns on the negative which range from 1 to 18 cycles per millimeter. The negative

is contact printed to produce the final

chart. Where the ANSI target was a transparency, this microfilm resolution target

is on opaque photographic paper (Figure 4).

The third reference material of interest

9
is the photographic density step tablet. The

tablet is produced from unexposed negative

film; mounted on a mechanical carriage, the

strip of film, for example, 25 mm wide and

150 mm long, is advanced 5 mm or so at a time under a slit through which light is projected onto the film. One end of the film

strip is started under the slit, exposed for

certain length of time, the film advanced,

a second section exposed for a longer period, and the procedure repeated with sucessively longer periods until perhaps 21 sec- tions have been exposed. When the film is

finally developed, the end product is one photographic density step tablet, each band

on the strip being of a greater diffuse density than the preceding. A similar procedure could be followed by printing directly

onto photographic paper; in this case, the

result would be a reflection density standard rather than one for transmission as was

the first. Reflection density standards can also be manufactured by normal ink printing

processes although the characteristics of

such materials are not precisely those of

photographic standards.

Some reference materials of a more specialized nature are: sine wave targets

which may be made by recording interference

fringes on film; the edge trace target which

is simply a film or paper target with a very

sharp boundary between the light and dark

regions; and a chart originally designed by

NBS for application to the testing of photographic lenses (it resembles a television

test pattern and is printed from engraved

plates)

The ANSI resolution pattern is really a prescription which describes the conventional manner for measuring and specifying the

resolving power of photographic materials;

as such, targets are made which conform to the specifications of the ANSI document but

they apparently are not sold commercially.

The five bar "microcopy resolution

chart" was designed for the resolution

testing of microfilm systems. The National

Microfilm Association, trade and standardization group for the industry, calls

for these charts in two documentary standards:

NMA MS104 for microfilm systems and NMA MS5

for microfiche. The charts conform to the

specifications of ISO DSI 3334, the draft

international standard on microfilm re- solution (which is nearing adoption as a formal standard). The Department of

Defense calls for the microcopy test chart

for testing microfilm systems they buy and

as part of their record-keeping procedures.

The basic document is MIL-M-9868D. The

military standard requires that the target

be recorded on the first and last frame of

every roll of microfilm used by its people;

the microfilm group suggests the procedure.

Ill III III III

III III III III

III ni

Ill III I III III

III III III

Figure 3. Basic pattern of the ANSI PH2.33

resolving power target

This microcopy resolution chart is manufactured on a competitive contract,

for the National Bureau of Standards (NBS),

by a major photographic company. The

charts bear the logo of the agency, an indication they have been examined by the

agency and found to meet rigid quality

specifications. The charts may be

acquired from the manufacturer or NBS. Since the charts uniquely satisfy the

industry standard, the international

standard, and military specifications,

they find wide usage. One may estimate

the number in use by counting the number

distributed annually and assuming,

probably conservatively, that the charts

have a two year lifetime before replacement. That puts the number of microcopy

resolution targets which are in circulation at around 20,000.

Photographic density step tablets

differ from resolution charts in that

their form is not specified; only the

basic measureable property, optical

density, is specified. Anyone may make

a step tablet by a procedure similar to that described earlier and sell it.

However, there are reportedly only three

places where fundamental measurements of

American National Standard diffuse

densities are performed: a photographic manufacturing company, an instruments maker, NBS. Each of the sources of fundamental density

measurements distribute step tablets: a great

number from the photographic company as products, a proportionately smaller number the

10
instrument maker ships with his densitometers

and supplies separately, and the number the

NBS offers as basic reference standards.

Other photographic suppliers and densitometer manufacturers contribute to the

total in circulation.

The tablets are used for direct visual

assessment of density, for calibration of

densitometers, for the evaluation of light

attenuators and as attenuators themselves.

As such, there are applications for step

tablets in photographic manufacturing and

processing, photography, medical radiology,

industrial radiography, and graphic arts. Optical density standards in the form of

transparencies and opaques are manufactured

and distributed primarily by four domestic

firms. There are about a dozen more or

less standard types with another dozen or

so special configurations. A spokesman for

a major photographic company estimates that

his firm markets around 150,000 annually

and that there may be a total of 500,000 in

circulation. The vast majority of these

are reflection density grey scales.

2.2.5 Science and People

People concerned with the basic thinking

about optical imaging measurements come from a wide variety of backgrounds, carry

different credentials, and belong to a spectrum of organizations. Those more or

less readily identifiable are described.

People engaged in theoretical and

analytical studies of the properties of

optical systems usually have degrees in

physics, engineering, chemistry or mathematics. A very few have studied at schools

with complete programs in optics or optical

engineering like the University of Arizona

or the University of Rochester's Institute

of Optics. Articles on current research

appear in the journals of the Optical

Society of America, the Society of Photographic Scientists and Engineers, the

American Institute of Physics, as well as independent publications like Applied

Optics, Optik and Optika Acta. Further

removed from the developments in research

and theory are the people who use optical

systems like ophthalmic test equipment.

There are three ways by which one can acquire custom-prescribed spectacles. One

could be examined by any of the 8,000 licensed

medical physicians who specialize in the eye. Their professional group is the American

Association of Ophthalmology. Second, one can

be examined by a licensed non-medical practittioner, an optometrist; there are 15,000

of them. Their groups are the American

Academy of Optometry and the American Optometric Association. Both ophthalmologists

and optometrists are licensed to examine

11

eyes and prescribe spectacle and contact

lenses. With a prescription in hand, one could get the lenses and frames or contact

lenses from any of 10,000 dispensing

opticians. Their organization is the

Guild of Prescription Opticians of America.

In the field of radiography, there are industrial and medical counterparts. When

x-ray pictures are taken of persons and

animals, the procedure is called radiology.

When the x-rays are taken of inanimate objects, like metal parts, the procedure is called radiography. The processes are essentially the same: in medicine, x-rays

from a source pass through a person, expose

a film and, after processing, the picture on the film is examined for flaws in the person, like cracked bones or tumors or tooth

decay; in industry, rays pass through

objects like airplane wings and the picture

is examined for flaws like cracks and empty

spaces inside the metal. About 10,000 physicians specialize in radiology; their

association is the American College of

Radiology. Dentists who use x-rays (and

MICROCOPY RESOLUTION TEST CHART

NATIONAL BUREAU OF STANDARDS-1963-A

Figure 4. The NBS Microcopy Resolution Chart
those who do not) may belong to the

American Dental Association. Over 90,000

medical x-ray technicians are certified

by the National Board of X-ray Technologists. Industrial radiographers are not

licensed but some are "certified". There

are about 15,000 of them and they may

belong to the Society for Non-Destructive

Evaluation. Medical and industrial people

both belong to the American Roentgen Ray

Society.

Depending on their commercial status,

photographers may join the Professional

Photographers of America or the more

general Photographic Society of America.

These groups mentioned here provide some

of the basic technical expertise for the

development of optical and photographic

documentary standards. Many others exist.

Besides from the technical publications

noted, the people involved get measurement

information from trade association journals

like "Micrographics" of the National Microfilm Association, from special interest

magazines like Optical Spectra and ElectroOptical Design, and from the books and sales

literature put out by manufacturers of

photographic and optical products.

The importance of this last source of

information should not be underestimated.

In some cases, the technical data sheet,

the film box, the instrument instruction

manual and the word of the salesman are

the major sources of information for the

person doing the measurement.

2.3 Realized Measurement Capabilities

Discussions with optical instrument

manufacturers, densitometer makers, producers of photographic products, and

others competent in the measurement field

have led to the following profile of

ranges and precisions associated with the

measurements

Resolution targets have patterns of

bars; the spatial frequency of a pattern

is the reciprocal of the total width of

one bar and one space and is expressed in

lines or cycles per millimeter (c/mm).

The lines on George Washington's face as

he appears on a dollar bill have a spatial

frequency of about 2 c/mm; the human eye

can resolve 10 to 20 c/mm. With these

figures in mind, one can outline the mea- surements associated with different

industries. The best engraved plates

have resoltuion limits of about 15 c/mm;

an inexpensive camera, 25; ct blueprint,

50; a decent amateur camera, 100; a professional-grade camera or a microfilm

system or a photoreconnaissance camera,

300; the finest quality microscope objective, 2000 c/mm. For photographic

film and plates, less than 55 c/mm is

low, 80 is medium, 120 high, 225 extremely

high and somewhere above 1000 c/mm the

highest attained (Figure 5).

One may recall that the spatial frequencies on the resolution chart which is the

standard for the microfilm industry range

from 1 c/mm to 18 c/mm. The 300 c/mm

which is the upper limit of performance

of microfilm systems can in principle be

obtained by photographing the chart at a reduction ratio of 20:1 or so. This means

the spatial frequencies in the reduced

image are 20 or more times those on the

chart. In the quality control of microfilm records, resolutions better than

144 c/mm are usually satisfactory levels

of performance in day-to-day operation.

Diffuse visual density is the measure of

how dark the blacks and greys of a negative

or print appear to the eye. It is the

logarithm of the ratio of the amount of

light which passes through the negative (or

is reflected from a print) to the amount

of light which strikes it. For a perfectly

clear negative, all the light gets through,

the ratio is 1 so the density is zero; for

a black negative, say only 1/10, 000th of

the light gets through, so the density is

4 (one can barely see the sun through that).

Fundamental measurements of density are made on an apparatus which measures density.

A transmission densitometer is a table- top

instrument which compares densities. It is

calibrated by placing a photographic density step tablet in it and adjusting a knob until a meter reads the value of density written on the tablet. A reflection

densitometer is calibrated on the ratio

of the amount of light reflected from

a sample and the amount reflected from a reference standard like a grey scale.

The reference standard is calibrated

against something which is arbitrarily

defined to have a zero density.

In medical radiology, the maximum transmission density of interest may be 1,

while a great deal of information the physician is looking for is at densities less

than about 0.2. In this range, he visually

detects density differences of the order

of 0.01. In industrial radiography, densities on the x-ray picture of metal parts

generally lie between 1.5 and 3. In this

range, an industrial radiographer can visually detect density differences of

0.02 to 0.03. With a decent densitometer

he can get down to 0.01. In general

photographic work like film processing,

the range of densities is 0 to 4. Densitometers which read to + 0.01 are sufficient. The manufacturers of photographic film generally work in the range

0 to 4 but some special tasks require

12
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10 100 1000 RESOLUTION (Lines per millimeter)

Figure 5. Spatial frequency ranges of some sensitized photographic materials

13
densities between 4 and 6 (which is outside the range of ordinary densitometers).

Some applications like film speed measurements involve densities below about 0.2

and require precisions greater than +_ 0.01; the newest top-of-the-line transmission densitometers have precisions of

+0.001 and find use in these and similar

critical situations.

Transmission densitometers are calibrated with photographic density tablets;

the tablet with which the user of the densitometer calibrates his instrument may be

far removed from the original source of

densities. The values of density on the

tablet may derive from a number of intermediate comparisons or they may be the

result of fundamental measurements at the source. The present range of original density

measurements, primary calibrations, is 0 to 4; accuracies are generally 1/2%,

corresponding to +^0.005 at a density of

1 and +0.02 at 4. NBS distributes calibrated reference standards for which the

stated uncertainty of densities below 1 is +0.005; at times, uncertainties of

+0.002 have been attained on that lab's

present apparatus. One densitometer

manufacturer reports fundamental mea- surements with observed deviations of

+0.0005. He markets a densitometer

which has a repeatability of _+ 0.001 for

densities less than 1. By comparing the data in the paragraph

above with the user requirements outlined

two paragraphs back, we can deduce that

present fundamental measurements of

transmission density meet the needs of

major users except those doing critical

photographic work or manufacturing photographic film and paper. These people

need standards with densities ranging

from 0 to 6 and accuracies of 1/2% or +^0.001 whichever is larger. Current

density standards offered by NBS have

densities from 0 to 4 with accuracies

of 1.0% or +_ 0.005 whichever is greater.

In reflection measurements, printers

(the ink on paper kind) generally work

with densities between 0.04 and 1.65.

The precisions they need can be obtained

by obtained by the good commercial densitometers which read to +0.01. Reflection density measurements performed by

NBS (on samples supplied by customers)

have these accuracies, +0.01 or 1/2%.

Photo manufacturers make measurements

from 0 to 2.5 or higher. Since visible

variations in the white area of a photograph correspond to density differences

of about 0.01, these manufacturers need

standards with accuracies of + 0.001

or 1/2%. Such standards are not cur- rently available.

One index of the effectiveness of a spectacle lens is its refractive power;

this property of the lens provides com- pensation for the eye's inability to focus properly. Refractive power is

expressed in diopters and is the reciprocal of focal length expressed in

meters.

One of the basic tools of eye exam- ination is a set of test lenses which

range from -16 to +16 diopters in power.

The examiner places different lenses

before the eye until the patient judges

he can best see the letters on the chart.

The lenses are graduated in steps of 1/4

diopters in power; a single lens of 1/8

diopter may be added to obtain values of

power between the 1/4 diopter values of the

primary lenses. A typical value of overall correction is 4 to 5 diopters; in rare

cases, 14 or 15 diopters of correction are required. The examiner usually prescribes

lens powers that are multiples of the 1/4

diopter unit; occasionally the power is

specified as a multiple of 1/8 diopter.

Lensometers (also called vertometers or focimeters) and spherometers are used in

the offices of ophthalmologists and optometrists, in the laboratories of dispensing

opticians, and by the optical companies

which manufacture finished spectacles and

unfinished blanks. The range of a lensometer is -20 to +20 diopters; by comparing

the spectacle with a lens of known power,

the device determines the refractive power

of the spectacle to a precision of + 1/8

diopter (where 1/16 D is the tolerance on

a finished lens specified by the ANSI

documents on first quality prescription

spectacle lenses). Spherometers measure

the radii of curvature of spherical

lenses; the scale on a spherometer may be

calibrated in dioptic power by assuming the

lens being measured is made of a specific

type of glass. The typical precision of

spherometer measurement is + 1/16 diopter;

under carefully controlled conditions,

± 1/32 diopter precisions are attainable

with the device. Lensometers and spherometers are comparison instruments. The

master standards are sets of lenses. Test

lenses have been calibrated for the major

manufacturers of ophthalmic instruments and

lenses by a NBS to accuracies of 1/500

diopter.

For some simple lenses like spectacles,

refractive power is an adequate measure of

effectiveness. For some lens systems like

microfilm readers, resolution is practical

gage of performance. But for high quality

lenses and advanced optical systems, no

14
single number can adequately characterize

image quality. Required are measurement

techniques which assess the combined

effects of system parameters: lens

material, focal length, aperture, aberrations, configuration and illumination.

Modulation transfer function is commonly

accepted as one means of lens performance

testing. Commercial systems measure MTF

over a range of spatial frequencies up

to about 100 c/mm. An interferometric

technique developed at NBS yields MTF

measurements for spatial frequencies up

to 250 c/mm and is in principle capable

of measurements out to 1000 c/mm; the

method also gives maximum values of

aberrations. The field of advanced lens

testing has not matured to the point

of having documentary standards, standard

test objects and instrumentation, or readily discernable patterns of measurement.

2.4 Dissemination and Enforcement Network

2.4.1 Central Standards Authorities

Put to an informed and detached observer,

the question of which measurement quantities

in imaging optics must derive from a central

standards authority no matter how remote,

such question would likely be answered with

a qualified: none. None of the measurement

quantities are based on quasi -legal definitions or chains of transfer from unique master standards. As a result, the role of a central authority is to act as the source of

authoritative, objective, and competent measurements and information; by doing so, such a source would serve to unify, not

determine the measurement system. The

National Bureau of Standards of the U.S.

Department of Commerce provides measurement services to this end.

2.4.2 State and Local Offices of Weights

Measures

Not surprisingly, measurements in imaging

optics do not fall within the present sphere

of measurement activities of state and

local offices of weights and measures or related agencies. In the field of imaging

optics, no analogue exists to the system

of mass measurements linking the international kilogram to the grocer's scale.

2.4.3 Standards and Testing Laboratories

Some organizations perform functions

similar to standards and test labs; they

are not part of an "enforcement and dissemination network".

Some optical companies will perform lens

testing since they have the facilities for

testing their own products. A handful of

companies advertise under "optical instrument calibrations" in the Optical Industry

and Systems Directory. Some general testing

firms will test anything, including optics,

if they are hired to do so. None of these

organizations are part of any network of

standards.

Two firms, a photographic products company

and a densitometer manufacturer, can perform

fundamental measurements of optical density;

they supply density standards as products or along with instruments. Both firms compare

the measurements they make with fundamental

measurements by buying and using standards

from NBS. The standards these two firms

distribute are referred to the national

standards rather mechanically derived from

them.

A group of testing laboratories measure

film densities as part of their testing of

other products; they don't test or measure

the film itself. They are the commercial

testing laboratories which do radiographic

non-destructive testing (NDT). Radiographic

inspections done for the military, either in

commercial labs or manufacturers' quality

control departments, must be based on density standards obtained directly from

NBS. Some regulatory agencies have similar

requirements.

2.4.4 Regulatory Agencies

Regulatory agencies and bodies which

have procurement specifications that tend to have pseudo-regulatory effects do not in

general control measurements; some have

"rules" which generally relate to optical

imaging systems. Information from standards

committee chairmen and agency officials

have led to the following conclusions:

Speataole lenses. All the states license

eye doctors, about half license optometrists,

about one third do opticians. The states

don't put performance specifications on the

manufactured lenses or police the delivery

system. A federal regulation governs the

mechanical but not the optical properties

of impact-resistant spectacle lenses. While

a 1974 bill pased by the Senate (S2368 on Medical Devices) was mentioned in the

popular press as potentially dealing with

the effectiveness of prescription lenses,

the Senate report (Calendar No. 646)

doesn't explicitly deal with the ophthalmic lenses.

Safety eyewear. The Department of

Health, Education and Welfare's National

Institute for Occupational Health and

Safety (NIOSH) which provides technical

support to the Department of Labor's

Occupational Safety and Health (OSHA)

actually measures the refractive power

15
of safety eyewear to determine con- formity to ANSI Z87.1, "Practice for

Occupational and Educational Eye and Face

Protection." As a part of its test procedure, NIOSH uses a test target

obtained from the National Bureau of

Standards

Aerial mapping oameras. The Department

of Interior's United States Geological

Survey (USGS) calibrates aerial cameras accordino to Department of Agriculture

(DOA) specifications. The DOA, the United

States Forestry Service, the Bureau of

Land Management, other federal agencies,

and many state departments of highways

and transportation have specifications

which either require or conform to the

DOA calibration requirements. The relevant camera calibration facility, originally part of NBS in the Department of

Commerce, was transferred to Interior

in 1972.

Medical x-ray. The States license

radiologists who are the doctors that

generally oversee hospital x-ray rooms and

who interpret the pictures for diagnostic

purposes. The Food and Drug Administration's

Bureau of Radiological Health (BRH) is charged

with enforcement of Public Law 90-602,

the Radiation for Health and Safety Act

of 1968, which has provisions dealing with

the components of diagnostic x-ray systems

including film and intensifier screens.

BRH enforces the provisions of documentary

standards developed in conjunction with

industry; they apply at the manufacturer's

level. BRH bases its measurements of the

response of films and intensifying screens

on optical density standards obtained from

NBS.

Microfilm systems. The Department of

Defense (DOD) requires performance testing

of microfilm and microfilm equipment in

its procurement and in its use. A series

of documents, the most basic of which is

MIL-M-9868D, describes resolution testing

and specifies a microcopy resolution

chart obtainable from NBS; it also calls

for photographic density standards from

the same source. The General Services

Administration (GSA) relies on the industry

standards which specify the same chart.

Industrial radiography and civilian

aviation. Responsibility for the airworthiness of all domestic civilian aircraft rests with the Department of Transportation's Frederal Aviation Agency. The

FAA basically has two procedural means for

insuring the structural integrity of aircraft. To provide for the reliability of

new aircraft before marketing, the FAA re- quires that a complete system of non- destructive testing (NDT) inspection be

developed during construction and made

available to buyers and users of aircraft.

NDT procedures, especially radiography, are emphasized. To provide for continued airworthiness, the FAA oversees the operation

of a system of certified inspection and

repair stations. Mechanics and inspectors

are certified (rather than licensed by the

FAA); the inspectors are employees of aircraft manufacturers, airlines, repair

services and independent NDT test labs.

When an unsafe condition is found in an aircraft after delivery, the FAA notifies

the operators of similar aircraft of the

potential problem and specifies the con- ditions, including NDT inspections, under

which the aircraft may continue in use;

as a last resort, the FAA can ground the

aircraft. During 1972, the FAA issued

147 reports of possible unsafe conditions

in the form of Administrative Directives

(AD's as they are called in the industry).

Of these 147, 66% requires NDT inspections.

Formal compliance with AD's is mandatory;

records of inspections and radiographs

become a matter of record.

Industrial radiography in military and

space applications. The Department of

Defense (DOD) operates by the book. One

document (MIL-I-45208A) outlines general

quality control standards and practices;

a second document (MIL-C-45662A) requires

that the densitometers used for the evaluation of radiographs be calibrated with

photographic step tablets obtained directly

from NBS. Other specifications describe

the procedures for the radiographic inspection of castings, welds, and forgings.

As a result, everyone who radiograph! cally

inspects military hardware - including

contractors who assemble systems, subcontractors who supply components, or independent test labs - is required to base his measurements of photographic

densities directly on standards obtained

from the National Bureau of Standards. In procurement of space vehicles and launch

systems, the National Aeronautics and Space

Agency (NASA) imposes similar requirements

on its suppliers.

Radiography of pipelines and nuclear

reactors. Responsibility for the safety

of oil and gas transmission pipelines rests

with the department of Transportation's

Hazardous Materials Regulation Board (HMRB).

Pipelines are constructed from short

sections of pipe that are welded into a continuous line; the weld seams are x-rayed.

HMRB specifications (Title 49, Chapter 1,

Section 195.234) tell how many welded seams must be inspected. The required number is

given in terms of a percentage of a day's

production of welded seams. Where the pipe is laid within populated

areas, within any incorporated subdivision

16
of a state, where the threat of water pollution from spillage exists, etc., 100% of

the welds must be radiographical ly inspected;

outside these areas, 10%. The HMRB document

states that the acceptability of welds

should be judged according to the American

Petroleum Institute's document on NOT testing,

API Standard 1104, section 6, current edition. The industry's standard specifies a density on the film but does not refer to the ANSI document which defines density nor

does it refer to any density standards. It leaves the final judgement on acceptablity

of welds to the company for which the pipeline is built. DOT does not license or certify radiographic inspectors of pipelines,

tank cars, or other equipment used in the

transport of dangerous substances.

Until recently the former Atomic Energy

Commission was responsible for the structural

integrity of nuclear reactors. The present

Nuclear Regulatory Cor?mission discharges this

responsbility in part by the enforcement of

mandatory NOT inspections of nuclear pressure vessels and components. The basic

procedures for inspections are given in the

American Society of Mechanical Engineer's

Boiler and Pressure Vessel Code (ASME BPVC,

1971). Fulfillment of the sections of the

code dealing with radiographic inspection

of nuclear reactors (ASME BPVC III, IV, and

VIII) is achieved either in plant or in

independent test laboratories. These manufacturing and testing facilities are tied

by photographic step tablets to NBS.

2.5 Direct Measurement Transaction

Matrix

2.5.1 Analysis of Suppliers and Users

To add structure to the presentation of

the information acquired on the measurement

system, organizations and entities which

enerate and use measurement information

Table 2) have been grouped according to their functions. To the commercial categories have been added others such as the governmental as well as the general

public. These categories have been arranged

in a 16 X 16 grid (Table 1). The groups

will be defined; their measurement capabilities, and the measurement information,

standards, and the products they deliver

will be given. The reader is cautioned

that statistical data on the value of products and services often involves multiplecounting; the total sum of the dollar

figures quoted may exceed the gross

national product.

Photographic Industry. These are manufacturers of photographic equipment

and supplies who appear in the Standard In- dustrial Classification category, SIC 3861.

They produce cameras, lenses for cameras,

sensitized paper, processing chemicals and

the assorted materials and equipment that

go with picture making. Besides amateur

still and movie equipment and film, there are non-amateur products in various categories; microfilm (including cameras,

readers, printers and processors), graphics

arts (which along with the appropriate

camera and film items includes photocopiers

and phototypesetting products), professional motion picture, aerial photography

and prepared photochemical s. According to

a private study of the industry ("Photographic Equipment and Supplies", Predicasts,

Cleveland, 1972), the markets are highly

concentrated. Nine companies represent

97% of domestic film sales and 80% of all

photographic products. Three firms produce 82% of the film and two 50% of all

goods. The photo industry, as a class,

uses the complete line of commercial and prototype instruments for measuring every con- ceivable property of lenses and film. One

company has an apparatus for doing fundamental

measurement of photographic density.

Some of the information they acquire

in research is fed into the system via

scientific literature; much of it is proprietary; the industry provides general

information in books and articles on photography, radiography and related topics. The

industry is represented on all the important

trade associations, professional and technical societies, and standards bodies related

to the field. They maintain close but for

the most part informal ties to the instrumentation manufacturers; in some cases, they make or have made densitometers. They

contribute to the development of federal

procurement specifications and to the man- datory standards which apply to them, e.g.

the FDA requirements on specifying x-ray

film-intensifying screen performance.

The private market survey quoted above

(based in part on DOC data) shows $4.4

billion in product shipment for 1970 and

projects sharply increased sales. Products

delivered into our Metal Product and Health

Establishment sectors are primarily radiographic film and equipment; into the Commercial --Institutional go the gamut of still

and motion picture, microfilm, x-ray, graphic

arts and photocopying products; into the

General Public, primarily amateur still and

motion picture cameras and film.

The photographic industry produces re- ference materials: photographic step tablets

for transmission density measurements, grey

scale charts for reflection density, and

the microcopy resolution chart (for NBS).

One manufacturer in a private communication

with NBS estimates that 500,000 density

standards are in use by people in appli17
Table 1: Direct Measurement Transaction Hatrix

DIRECT MEASUREMENTS

TRANSACTIONS HATRIX FOR OPTICS

U

S

ER

S

_

KNOWLEDGE COttWNITY

^,

DOCUMENTARY

SPECIFICATIONS

„

INSTRUMENTATION

MANUFACTURERS

CO

ooz

4

„,

U.S.

GEOLOGICAL

SURVEY

o,

STATE

AND

LOCAL

AGENCIES QOQ

7 •

REGULATORY

AGENCIES

«»

FEDERAL

AGENCIES

o

PHOTO

INDUSTRY

-

OPTICAL

INDUSTRY

S

METAL

PRODUCTS

-

STANDARDS

AND

"

TEST

UBS

-

COMMERCIAL

*•

INSTITUTIONAL

-

HEALTH

ESTABLISHMENT

S

GENERAL

PUBLIC

SUPPLIERS

1

' KNOWLEDGE COWWNITY 3 2 3 41^ 2 3 3 2 4 4 2 2 2

DOCUMENTARY SPECIFICATIONS

2 4

^ 3 3

" 4

1

3 2 4 2 3 0 3 3 2 1

•> INSTRUMENTATION MANUFACTURERS

3 43 4

2

3

1 0 2 1 1 2 3 2 2 3 4

f

NBS

0 1

£. 1 3 0c

2

1

J 1 2 03 1 2 0

g

1 N

1

1 4

3

3 1

1 P

4 1 2 0

3 1 4

0

1 3 4 0

4

4 0

4

2 1 3 0

1 0

1

1 0

1

' U.S. GEOLOGICAL

SURVEY 1 2

2

1 4 3 3 4

1 0

1

STATE AND LOCAL AGENCIES 0 3

3 1 0 1

J OOD 1 2 1

1 3 4 2 3 4 1

o" REGULATORY AGENCIES 1 1 0

1 0 2 3 0

1

1 1 2 0

9 FEDERAL AGENCIES 1 1 2 3 2

10 PHOTO INDUSTRY

2 4 4 3 4 0

4

0

4 2 4 4 3 3 4

1 1 4

2

7c nu 4

0 n

OPTICAL INDUSTRY

I 4 4 2

"5 1 3

1 3 4 2 4 2 3 4

3 2 4 4 1 4

2 12 METAL PRODUCTS 3 1 2

1

1 4 3 2

4 44

4

4 1 4

2

4

4

STANDARDS AND TEST LABS

1 2 1

2

2

1

4 0

4 2 3 1

COMMERCIAL

INSTITUTIONAL

3 3 3

3

3

1

4 2 2 2 4 4 3 3 4 4

HEALTH ESTABLISHMENT 1 2 0 0 3 3 1 3 1 3 4 1 4

2 16 GENERAL PUBLIC

0

1 1 1 2 2 3 3

KEY TO ENTRIES

A IMPORTANCE OR CRITICALITY OF TRANSACTION B ADEQUACY OF TRANSACTION SERVICE

Purely a matter of convenience

Economically compelling; strongly desirable

Legally required; alternate sources unsatisfactory

Matters of life and death; sole source; essential

Declining

Stable

Growing

Explosive growth

Under control Marginally OK Seriously deficient

Out of control

18
cations ranging from photography, radiography, gravure printing, phototypesetting,

and television broadcasting to consummer

product package labelling (machine readable

labels). The microcopy resolution charts

which are the microfilm industry standard are produced on a competitive contract by a photo

manufacturer for NBS; he distributes about

half of them directly to users, about half

go to NBS. Judging by the number distributed

anually and estimating serviceable lifetime,

one would put the number in use at any given

time as around 20,000; apart from their primary use in the evaluation of microfilm

systems, they are general purpose tools in

optical testing. Users appear in the photo,

optical, and commercial-institutional sectors . Optical Industry. A survey of industry

(Institute of Graphics Communication, 1973)

shows over 1500 companies making equipment

related to optics, this includes everything

from lenses to lasers. A Department of

Commerce source, writing in Optical Industry

News, July 1973, counted 303 firms which

manufacture lenses or instruments that use lenses (excluding photographic equipment).

Many of the 303 companies are small.

Statistics compiled by the Bureau of Census

(Current Industrial Reports, MA-38B(73)-1)

show just the manufacturers with sales over $100,000: for example, only four producers of ophthalmic lenses and five of optical

test equipment (including microscopes) had

reported sales above that level in 1972 (see

Table 3).

The optical industry is diverse, with

the high-technology companies often over- lapping into the photo industry. One com- pany might manufacture space telescopes,

reconnaissance cameras, microfilm systems,

and ophthalmic goods; as such it would possess

the entire range of test equipment from

interferometers to spherometers . Another

company might produce inexpensive general

purpose lenses, sunglasses and ophthalmic

goods; its measurement facilities might

run to the simpler forms of refractive

power and distortion testing. Between

these two extremes is an entire spectrum

In terms of its relation with standards

committees and regulatory agencies, this

industry follows the pattern described for

the photo industry. Except for ophthalmic

lenses, test sets and the ANSI documents

on prescription lenses, there are apparently no other physical or documentary

standards related directly to the industry.

Into the general public sector, the industry delivers spectacles, contact lenses,

binoculars and amateur telescopes. To the

health establishment go research microscopes, ophthalmic equipment like test

Table 2. Interaction Matrix Suppliers and

Users: SIC Codes of Non-Governmental Entries

SIC Transaction Matrix Category and Members

Instrumentation Manufacturers

3611 Measurement and test equipment

3811 Scientific instruments

3693 Radiographic apparatus

Photographic Industry

3861 PhotograiDhic equipment and supplies

Optical Industry

3831 Optical lenses and equipment

3851 Ophthalmic goods

3861 Photoreconnaissance systems

3861 Microcopying systems

3861 Photocopying machines

Metal Products Manufacturers

1925 Guided missiles and space vehicles

3360 Castings

3390 Forgings

3440 Fabricated structural steel

3490 Pipes, valves and fittings

3511 Turbines and generator sets 3533 Oilfield machinery and equipment

3711 Motor vehicles

3721 Aircraft

3731 Shipbuilding and repair

Standards and Testing Laboratories

7397 Commercial Testing Laboratories

7397 Non-profit research institutions

Commercial -Institutional Services

1799 Felding contractors

2751 Commercial printing

4511 Certified scheduled aircarriers

4521 Non-scheduled aircarriers

4582 Aircraft service and repair

5300 Retail trade

6000 Banking

6100 Credit agencies

6300 Insurance companies

7333 Aerial photographic services

7395 Photofinishing

7399 Mapmaking and aerial surveying

7692 Weld shops

7813 Motion picture production services

7815 Still and slide picture production

8200 Educational services

Health Establishment

8011 Offices of physicians

8021 Offices of dentists

8042 Offices of optometrists and opticians

8061 Hospitals

8071 Clinical medical laboratories

8922 Medical research institutions

19
lenses, refractometers , retinoscopes and

others, plus a whole series of special devices for peering into the various orifices

of the human body. Besides these ordinary

devices, federal agencies or their con- tractors are supplied special products; e.g.,

to the FBI went a lens for a finger print

analyzer and to the AEC similarly costly

lenses for a laser-induced hydrogen fusion

experiment. The industry supplies to the

DOD the optical products to carry out its

mission, like binoculars, telescopes,

sighting-fire control -tracking devices, and

to support its personnel, like the ophthalmic

and medical devices. The Bureau of Census

report quoted above shows 1972 sales of

ophthalmic lenses of $190 million and non- ophthalmic lenses and instruments of $300

million, for a total in non-photographic

lenses and instruments of $490 million.

Meixil Products. This is a broad category

which crosses industry lines; it includes

the major industries which use radiography

to non-destructively test their own metal

products. Such products are formed by casting, forging, rolling, and other shaping

processes; finished assemblies may be precision welded. A survey of industry

(Hitchcock Publishing Company, Fall 1971)

found 6,300 plants that use radiographic

inspection of metal products. Those of primary interest manufacture castings, forgings,

fabricated metal structures, pipes, valves,

and fittings; produce turbines, generator

sets, oilfield machinery and equipment,

motor vehicles, aircraft and ships (see

Table 1 for SIC categories).

The information transfer from this group

of industries in primarily into those firms

which buy the products that are radiographically inspected; the measurement capabilities consist of densitometers for the mea- surement of photographic densities on radiographs. The companies in this category

supply the Commercial -Institutional sector

with manufactured goods; aircraft, pipelines, nuclear reactor pressure vessels and

components, ships, and the like. To DOD

they supply ordnance: missiles, aircraft,

tanks, small arms, and the rest. To the

general public, in the main, go automobiles.

The volume of product generated by this

sector is large. It is practical to cite

only some examples of metal products subjected to criticial radiographic inspection;

Department of Commerce data (Current In- dustrial Reports, MA-38B(1)-1, 1973) show

completed aircraft sales for one year of

$7.6 billion and guided missile and space

vehicles sales of $4.6 billion; AEC data

from that source indicates $64 billion a- warded in contracts between 1965 and 1973;

for the construction of nuclear reactors;

an American Petroleum Institute report

Table 3: 1972 Shipments of Non-Ophthalmic

and Non-Photographic Lenses and Lens Instruments

Instruments

Binoculars

Alignment and Display^

3 Test Equipment

Lenses and Components^

5 General

Sighting and Tracking^

No. 1 Shipments

Firms ($ millions)

2

3

5 27

14

33

5.0

35.8

51.0

92.3

95.8

1. Companies with reported shipments over $100,000 in the year.

2. Except photographic.

3. Including standard sources, modulators,

microscopes, comparators, interferometers.

4. Including mirrors, filters, gratings, re- flectors, coatings, light amplifiers, etc.

5. Excluding analytical instruments.

6. Made from lenses produced in plant and

purchased.

(Source: U.S. Department of Commerce, "Current Industrial Reports, MA-38B(72)-1.

)

("Petroleum Facts and Figures", API,

1971) points to $600 million in new pipeline constructed annually.

The Testing and Standards Laboratories

category is an adjunct to the Metals Product

group. These are independent companies which

perform radiographic inspection as a service,

either in their own facilities or, as in the case of aircraft inspection, on site. They

appear is SIC 7397. Their measurement capabilities are like those of the Metal Product

entries. No dollar value has been attributed

to them since these same companies very often

perform NOT which does not involve radiography.

Cotmevcial and Industrial. This category

includes those organizations which use the

products of the photographic, optical and

metal industries in order to supply services

and goods to people. Those specifically

mentioned have been identified as measuring

optical image properties either in the course

of a service they provide or in testing what

they procure:

*Photofinishing labs, motion picture production facilities, still and slide picture

producers, commercial photographers, and

television broadcasters;

Graphic art and design companies, lithographic and gravure printers, phototypetypesetters, photocopying and blueprinting

establ ishments

Microfilm recording and developing ser- vices and a host of microfilm users, some important ones being in retail trade, bank20
ing, credit, insurance, and educational services ; *X-ray radiography users outside manufacturing, including scheduled and non-scheduled

aircarriers, aircraft service and repair facilities, pipeline operators, and natural

gas and electric utilities.

The measurement capabilities of these

establishments fall into three categories:

users of commercial transmission densitometers such as the photofinishers , photographers, and radiographic inspectors; users

of commereial reflection densitometers such

as the graphics arts group; and users of test

standards with specific instrumentation such

as the microfilm users for resolution charts

and the television broodcasters for reflection density grey scales.

The output of this sector is product and

service, not measurement information, and

an estimate of the total cost of these services has not been made. Just to hint at

the magnitude, some data for photo services:

A private market study (The Photographic

Industry, Arthur D. Little Inc., 1971) estimated that amateur photofinishing, 40% of

which was handled through drugstores, cost

$400 million; microfilm services $250 million;

professional still photography like wedding

pictures, portraits and industrial applications , $145 mil lion.

Health Establishment. This category is

primarily based on those portions of the

health care service devoted to either supplying prescription spectacles and contact

lenses or to x-ray examination. By SIC

grouping, it includes; physicians (either

ophthalmologists or radiologists), dentists,

optometrists and opticians, hospitals, clinical laboratories and medical research facilities, and the general group of medical people who use optical instruments. The category also includes the professional associations like the American Medical and Dental

Associations, the College of Radiology, etc. The measurement capabilities of eye

examiners have been described in section

2.3; those of medical radiology vary from

the research installation which extracts

quantitative data from radiographs by densitometry to the ordinary hospital x-ray lab

in which subjective judgments of density are apparently the norm. Information flow from

the medical community to the film manufacturers and standards bodies like ANSI is

primarily via their professional organizations

like the medical and dental associations.

The product delivered into the public sector

is eye care and diagnosis of abnormal con- ditions like tooth decay, bone fractures,

and pathological conditions. The dollar

value of product is large. A private cor- poration compiled data from a 1970 U.S.

Public Health Survey, from the American

College of Radiology and from the Bureau

of Public Health Insurance; they reported

in a confidential proposal to the National

Science Foundation that the cost of nondental medical x-rays was between $2 and

$4 billion. An undocumented reference in

the popular press (Parade Magazine, Dec.

13, 1973) gives the cost of eye care at

$2 billion. For perspective, the Department of Commerce estimate of the total

cost of health care for 1973 was $97 billion

(Current Industrial Reports, MA-38B (73)-l).

The Instrumentation Industry has been

described above. In summary, the instruments

range from densitometers (reflection and

transmission), microdensitometers , interferometers, lensometers, spherometers , and MTF devices to all the loose lenses, light

sources and components from which to build a test apparatus.

The industry has high input into the

scientific literature and standards committees. It overlaps with the photo and optical

industries; its measurement capabilities are

the same. One densitometer manufacturer

(like one photographic) has an apparatus for

fundamental measurement of optical density.

Standards and densitometers are supplied to radiographic people in the metal "products

sector. The entire range of people who do

photographic processing, and to the commercial

printers; special densitometers used in

chemical analysis go to the health and com- mercial sectors. Optical equipment including

test lenses and lensometers go to the health

establishment; a great deal finds its way to the photo and optical industries. Product

shipments annually amount to $4 to $6 million

in densitometers and $35 million in optical

test equipment Table 7. Central Standards Authorities. The

National Bureau of Standards contributes to the system by calibrating the master test

lenses of ophthalmic goods manufacturers,

providing optical density standards to photographic manufacturers and others,

issuing the test charts which are the microfilm industry's standard, performing high

accuracy lens tests, and supplying density

standards to vendors who need to meet certain

military and/or health and safety regulations.

The U.S. Geological Survey calibrates aerial cameras for people doing business with the

state highway departments, the Department of

Agriculture and other federal agencies; these are basically distortion measurements.

The General Public has input to the

system through consumer groups on standards

committees, through public hearings on federal agency operations, and as customers

of commercial, industrial and health facilities.

21
2.5.2 Highlights of Major Users

The measurement system in imaging optics

is a complex one. Different people measure

different things for different reasons with

different people looking over their shoulders. Only a few examples can be cited.

Refvaotive power; speataoles. If you are

not one of the 100 million people who already wear glasses or contact lenses (HEW Report

No. (HRS) 75-1520), you may eventually need

them. For an eye examination you go to a medical ophthalmologist or a non-medical

optometrist. The former is always licensed

by the state because he's an MD; the latter

only in some states. While you're looking at

an eye chart, the examiner places lenses

from a test set before your eyes until you

can read the little letters. The test lenses are calibrated by the manufacturer of

ophthalmic goods who supplied them. The

examiner can measure the refractive power of

the lenses on a lensometer or spherometer in

his office. The devices are factory-calibrated. The examiner writes a prescription

for lenses equivalent to the ones that worked

best for you. The prescription is filled by

a dispenser, either through the examiner or

a non-licensed dispensing optician. The

lenses can be fabricated by either a large

optical company or by a small laboratory

which obtains the unfinished lenses from a large company. In either case, the same basic equipment is used to measure refractive

power (see section 2.2.2.2 for instruments

and 2.3 for accuracies). The lensometer is

very likely from a company which has master

test lenses calibrated by the National Bureau

of Standards. The dispensing optician, the

laboratory which ground the lenses (either

the small lab or the large optical company)

and the examiner use basically the same instruments. There is a voluntary industry

standard for first-quality prescription

lenses. The federal government only requires

that safety glasses be resistant to shatter.

So you get your glasses and wear them. They

may be fine; they may not. By means of a private communication to NBS, an Associate

Director of the Optometric Center of New

York reported that of 2270 patients'

ophthalmic materials examined in 1973-4, 50% were of unsatisfactory performance due to fabrication: lenses either ground or set into

frames improperly.

Transmission density; photography. When

you use a camera that has different shutter

speeds and lens openings, you must take into

account the speed of the film to set the

exposure. On the film package is an "ASA

number" which tells the film speed: like

25 or 64 or 3000. ASA stands for American

Standards Association, the former name of the

American National Standards Institute (ANSI);

this organization has written standards which

describe the conventional ways to determine

how much light is required to produce a certain density on the film (see section 2.1).

All the photographic companies which manu- facture or market film in the U.S. use the

convention, (see Photographic Industry in

section 2.5.1).

You set the camera, shoot a roll of film,

and take it to the drugstore which sends it

out to a photofinishing laboratory for processing. The processor develops the negatives

and makes prints. In monitoring the development process he measures the photographic

density of the negative with a densitometer.

To calibrate the densitometer he uses a photographic step tablet; one had come with

the instrument and he bought more from a photo

company.

The company which manufactured the film

and those which produced the step tablets

use densitometers and step tablets in the same way as the processor. In addition, the

manufacturers use them as tools in research,

production, quality control and the basis

for the assignment of ASA speed ratings of

film. All major domestic producers of film

and the two dominant foreign firms which

sell in the U.S. have photographic density

step tablets from the National Bureau of

Standards. Voluntary use of the standards

provides a basis for uniformity of measurements and may lend credence to product

information; it also aids the U.S. firms

in their marketing to any foreign consumers who prefer that measurements be traceable to

a governmental authority.

So you got your prints back from the drugstore and maybe they're not too good. It's probably your fault.

Transmission density: aircraft. The

commercial airliner in which you travel has

had non-destructive testing (NDT) quite a few

times. The plane itself probably gets a thorough inspection after every 6000 hours

of flight; specific parts more often. If

aircraft of the model you're in have been

involved in accidents due to structural

failure (that's rare), the FAA might have

issued an Administrative Directive requiring

frequent radiographic inspection. The

inspection takes place in the airline's facilities or at an independent service and repair

station. The inspector is certified by the

FAA. He may be an employee of the airline,

the repair service or NDT test laboratory.

The x-ray film comes from the manufacturer

marked with a general speed classification.

The aircraft was also inspected during

assembly by the manufacturer. The FAA re- quires that an NDT procedure be developed

during the plane's construction and manuals

22
describing it go to the purchaser of the

plane. The castings and forgings of parts

like turbines, airframe, landing gear, etc., were inspected during their manufacture,

either at the plant or in a NDT test lab.

The same companies which manufacture the

passenger transport aircraft for the airlines also manufacture the aircraft for the

military. Radiographic inspection processes

are the same in each case; the density on a radiograph is checked on a densitometer

calibrated with a photographic density

step tablet. The DOD formally requires

that densitometers be calibrated with step

tablets from the National Bureau of Standards; the FAA has similar requiretnents

The effectiveness of federal safety

standards regarding the structural

integrity of aircraft is evident in

statistics complied by the National Transportation Safety Board, and independent

federal agency responsible for the investigation of aircraft accidents. According

to NTSB data for the years 1960 to 1969,

fatal crashes of conmercial airliners

occurred at an average rate of two per

million departures. In the period 1970

to 1974, only two fatal crashes of com- merical aircraft resulted from structural

failure due to any cause; in the same period, an average of about 40 private

planes per year were involved in fatal

crashes due to structural fai lured.

An NTSB report on one particular

private-plane crash shows the importance

of careful radiographic inspection,

including densi tometric measurements of

radiographs. According to the NTSB Accident

Report (Air Iowa, Inc., Beech E183, N3I0WA,

Davenport, Iowa, April 19, 1973, adopted

October 3, 1973):

"Air Iowa, Inc., Flight 333, a Beech Aircraft Model E18S, operating

as a scheduled air taxi passenger

flight, crashed into an open, plowed

field about 170^ central standard

time. April 19, 1973, while approaching

the Municipal Airport at Davenport,

Iowa, for a landing. The accident

occurred approximately 3 miles southwest of the Davenport Airport. The

pilot and five passengers were fatally

injured. There were no injuries to persons on the ground. The aircraft

was destroyed by impact forces; there

was no fire".

"The National Transportation Safety

Board determines that the probable

cause of this accident was the inflight failure of the right wing,

which resulted from a preexisting

fatigue crack in the lower spar cap

of the wing at Wing Station 81. Although the fatigue crack existed and

was discernible during inspections

conducted over the 6-year period prior

to this accident, it was not detected."

"The procedures for detection of

cracks in the elliotical front spar

cap of the wing center section are outlined in FAA Amendment 39-1526 to Airworthiness Directive 72-20-5,

effective September 29, 1972. The

radiograph exoosure of the X-ray film,

also specified in this amendment, should

be from 1.5 to 2.8 on the densitometer of the National Bureau of Standards

density scale. The radiograph exposures

of several of the X-ray films examined were found to be outside the allov/able

tolerances. The densities of this film

ranged from 0.5 to 5.0. The procedures

and densities specified in Amendment 39-

1526 were also specified in the amendments issued before September 1972."

"The Safety Board concludes that the

concerned repair stations did not comply

with the wing spar inspection procedures

prescribed in the applicable airworthiness

directives and that quality control of

their inspection programs was practically

nonexistent. As a result, the aircraft

was flown with a detectable crack in the

elliptical tube of the lower main spar at Right WS 81 until the crack became large

enough to cause complete failure.

Furthermore, there are no well-defined

standards for certifying a repair station

as a radiographic facility or for

oualitying a technician for non-destructive

testing.

Resolution; miorofilm. Although anything

from a credit rating to a birth certificate

may be stored on microfilm, the average per- son has probably never seen any. Microfilm is used in amny forms: 16 and

35 mm strips in reel, cartridge, and cassetts;

sheets called fiche (like feesh), aperture

cards (which are nunched computer cards with

microfilm windows) and micropaques (microimages recorded on paper). Use falls into

four major categories:

1) engineering documentation - graphs,

drawings, and the like. Major industries

in this category include transportation,

construction, manufacturing, utilities

and government.

2) security microfilming - for material that

doesn't need updating but must be re- tained for "security" and historical

purposes

3) microoubl ishing - the placement of original

documents on mircofilm for sale or the

microfilming of published documents for

resale (magazines, newspapers, catalogues,

etc.). The Government Printing Office

has begun a program to offer its

publications on microfilm.

23
4) recordkeeping - the daily handling and

processing of business information

involving generation, storage, retrieval,

dissemination and updating.

The users of microfilm are numerous and

what they record defies categorization: legal

records, birth and death certificates, auto

registrations, manuscripts, books, doctoral

theses, periodicals, medical records, x-ray

radiographs, parts lists, catalogues, engineering drawings, the records of health and

life insurance companies, banks, airlines,

and manufacturers of all types. Many government agencies use microfilm, including the

Library of Congress, Patent Office, HEW, AEC,

NASA, DOD, as well as the National Technical

Information Service.

The National Microfilm Association (NMA)

is the trade association and standards body

for the industry. This organization has

adopted the National Bureau of Standards

microcopy resolution chart for their re- commended practice to evaluate cameras,

readers, and processes; the NMA recommends

that the resolution chart be photographed

onto the first and last frame of each roll

of microfilm.

Reflection density: gravure printing. The

supplement to your Sunday newspaper is gravure

printed as are hundreds of other things from

catalogues to gift wrap. There are different

kinds of gravure-printing but they're all

photomechanical. Printing is done from a re- cessed image etched into a plate or cylinder;

tiny wells of variable depth and size deposit

ink onto a surface like paper or cloth. In their most recent survey (1971), the Gravure

Technical Association questioned gravure press

manufacturers, engravers, ink manufacturers

and others; the consensus was that there were

about 15,000 gravure press units in the U.S.,

not including textile printers. The same organization estimated that the dollar value

of gravure printing in 1971 was $2.8 billion.

Reflection densitometers are used to measure the optical density of ink on paper; the

language of densitometry is used to com- municate between the photographer, the en- graver, the printer, the ink maker, and

the advertising agencies.

Reflection densitometers are calibrated

using standards similar to photographic step

tablets, that is, they have a range of tones. However, this tonal range may be in shades of

grey or shades of color. The reflection

standards are produced photographically or by

ink printing; they originate from photographic

manufacturers, densitometer manufacturers and

other sources.

The grey standards are calibrated by applying the prescription outlined in an ANSI

standard; the measurement is basically a com- parison to something defined as white, like

magnesium oxide as specified by an ANSI document or barium sulfate as endorsed by common industry practice.

3. IMPACT, STATUS, AND TRENDS OF THE MEASUREMENT SYSTEM

3.1 Impacts of Measurements

3.1.1 Functional, Technological and

Scientific Impacts

To avoid a tedious enumeration of the many

industrial, scientific, and medical applications of optical and photographic devices,

a few of the more esoteric and unfamiliar

examples in which quantitative data is ex- tracted from film or lens devices and a few

in which the higher grades of film or lens are used will be given.

Density variations are the information

carriers in a film image. In the fields of

astronomy, spectroscopy, chemical chromatography and photoreconnaissance, the variations are measured and information like

star magnitudes , physical composition,

chemical concentrations, and subject con- tent derived. In medicine, a radiograph

might be scanned with a densitometer to study bone decalcification. In holography,

high grade film may be required, for ex- ample, to record finely detailed three dimensional pictures of biological structures; similarly, for holographic com- puter data storage devices.

Outside photography, precision lenses

and non-plane mirrors (which are tested

in similar fashions) are used in astronomy,

in the manufacture of lasers, in holographic applications, in laser-induced

fusion research, and in applications like

photosensitive semiconductor memory devices. In semiconductor fabrication, both

photographic techniques and the use of optical devices as measurement tools are routine and essential.

3.1.2 Economic Impacts - Cost and Benefits

Measurements of refractive power are essential to the manufacture of optical

systems which use the focal properties of

lenses. Spectacles cannot be prescribed or fabricated, a camera cannot be designed or built, without them. The DOC Office of

Business Analysis reports (Optical Industry

News, Aug. 1973) that total shipments of

lenses and optical instruments in all industries amounted to $485 million. Cost of

the measurements involved in this production

have not been determined.

Similarly, measurements of optical density

are fundamental to the design, manufacture

and use of photographic materials. Total

shipments of sensitized goods in 1970, $1.7

24
Table 4. Author's Composite of the Industrial and Medical Radiographic Measurement

Systems of 1970.^

Facilities

Installations

X-ray units

Radiographers

Technicians

Annual use

Film

Equipment

Radiographs

Cost

Industrial

6300

25,000

15,000

$29 million

$37 million

70 million"^

$350 million"^

Med i car

115,000

10,000

90,000

$210 million

$96 million

625 million

$4.2 billion

1. Sources of data for each entry cited

in text.

2. Excludes dental personnel and x-ray

units

3. In-house estimate based on a comparison of film and equipment usage, personnel,

and operating costs in the two fields.

billion; photographic equipment, $1.1 billion; cost of photofinishing services, $0.9

billion; total product involved, $4 billion.

(Private market surveys by Arthur D. Little,

Inc. and Predicasts, Inc.). Cost of measurement also is undetermined.

These two categories, lens and film, are most intimately connected with measurements

of imaging properties; they are the basic

manufactured goods. Some of the users of

these products also do measurements.

An eye examination is a measurement of

the refractive properties of the eye. The

bill from the examiner who writes the prescription is the cost of his measurement,

maybe $15. Since 100 million people wear

prescription spectacles, it's a large overall

cost for those measurements. Data on the

cost of measurement in the manufacture of

the $190 million worth of ophthalmic lenses

sold in 1972 (see section 2.5.1) is un- available.

In the field of industrial radiography

direct measurement of the photographic density are made of x-ray radiographs in order

to insure good image visibility. The Society

of Non-Destructive Evaluation in a private

communication to NBS estimated there are

15,000 industrial radiographers. A survey

by the Hitchcock Publishing Company found

6,300 plants with 25,000 x-ray units using

Table 5. Profile of a Hypothetical Steel

Foundry.

Company name: The Hypothetical Steel Foundry*

Annual sales: $1 million

Products: Steel valves, flanges, pumps

Customers: Nuclear reactor, refinery, and

power plant builders.

Inspec. Code: ASME BPVC, Sections III, VIII.

Equipment: Xray sources-300kv tube

-Iridium 192 -Cobalt 60

Manual darkroom

Accessories

Shielded room Densitometer

Personnel

Radiographs

Film Cost:

Equipment:

Film:

Salaries:

Acceptance judge

Interpreter

Technician

$10k

$4k

$5k

$5k

$2k

$10k

$lk

$15k

$10k

$6k

10,000

$15k

$37k

$15k

$30k

*Formulated by a manager of a radiographic

training center.

the technique. The survey of the photographic industry shows $65 million dollars worth

of film and equipment were bought in 1970. An in-house estimate (based on film con- sumption) is that between 45 and 90 million

industrial radiographs were made in that

year at a cost of $350 million (Table 4).

Some of the products directly affected

by these measurements in years for which we

can give data are: the 9,000 miles of natural

gas pipeline costing $600 million built in

1970 (API Petroleum Facts and Figures, 1971)

the 16,000 aircraft costing $7.61 billion

completed in 1973 as well as $4.6 billion

worth of guided missiles, launch and space

vehicles and the 180 central station nuclear reactors for which $64 billion in con- tracts were let between 1965 and 1973

(Current Industrial Reports cited above).

To see what the cost benefit of a single

densitometer measurement of a radiograph is, we asked the manager of a radiographic

training center to sketch a "Hypothetical

Steel Foundry" which makes cast components

25
Table 6. Cost of a Single "Traceable"

Measurement at a Hypothetical Steel

Foundry.

INDo o tc[J laUlcL

T m' 1 1 a 1 1 III L 1 a 1 ^72 00

MiUlUal v^cpr cC 1 a Ucu uvcr c yt^} i?fi on Ppr raHinnranh ( nf 1(1 000^ $ 0.04

RpfiQ *i 1'nmpl'Pr

1 il 1 L 1 a 1 t-\ c;nn no

Miiiiudi ^ucjJi la ucu uvci ^ j * ^ / iwo 00

Ppr radinnranh (IQt nf 10 000^ $ 0.30

Pa 1 "1 hv^;i "hi nn Hpnc i f*nmp1"Pr

rviiMUui Ar)niial fca1av*\/ ^ouiuijf )i01 n\/Pv^hpaHi uvciiicauy $300 00

Ppr radioaranh (10% of 10 000) $ 0.30

Film r 1 1 III Anmia 1 $15 000 00 Per radiograph (10,000) $1.50

Salaries

Annual $30,000.00

Per radiograph $3.00

Overhead

Annual $45,000.00

Per radiograph $4.50

Total per "traceable radiograph" $9.64

for nuclear reactors. The company has

radiographic equipment costing $35,000, including a $1,000 densitometer. With an acceptance judge, an interpreter/ technique

formulator and a technician, its salary

costs in 1973 were $30,000. It does $1

million in business and makes 10,000 radiographs a year. The cost of the radiographic

measurement is $10, including salaries,

overhead, the film and the densitometers;

not the big x-ray equipment. One densitometer measurement is on the radiograph of

a flange (see Tables 5 and 6). An article on NOT (Materials Evaluation,

May 1973) describes the intent of that

measurement. A central station nuclear

reactor of 1000 Megawatt capacity is described as having a down-time cost of non- operation of between $100,000 and $200,000

per day. For a simple part breakdown, like

a broken flange, time and materials for

part replacement per se may be $10,000.

But where the repair work is hindered by

residual radiation as well as loss of

primary coolant, cost of clean-up,

shielding and additional personnel must be

counted. Total cost of replacement of one faulty flange would be about $250,000.

To avoid this cost (flange failure) the

facility owner may follow a code which prescribes the use of licensed welders and

radiographic inspection. For this avoidance

procedure to be worth its cost the probability

of flange failue should be reduced by the procedure to the point where the return on ex- pected avoidance just equals the marginal

cost of preventions. One of these latter

costs is the $10 one estimated in Table 6 for traceability of film density measurement

to NBS. Presumably this cost "pays its way"

in avoidance, but by exactly how much is not

known.

In the field of medical radiology,

subjective measurements of photographic density are made by physicians and dentists.

Market surveys identified above show 1970

sales of medical x-ray film of $210 million

and equipment of $96 million. There are about 115,000 diagnostic x-ray units in place. A confidential proposal to the National

Science Foundation analyzed the cost of mea- surement for the year 1970. In a medical

system consisting of 10,000 radiologists supported by 90,000 technicians, 325 million

medical x-rays were taken of 110 million

patients at a cost (fees, supplies, depreciated equipment, and overhead) of $3.9 billion; another 300 million x-rays were taken

by dentists at a cost of $0.3 billion. That

comes out to $12 for a measurement on a leg

(Table 7) and $1 for a measurement on a mouth.

The same surveys of the photographic industry quoted above show primary equipment

and film sales in the microfilm industry of

$280 million. Equipment sales and rentals

totalled $78 million in 1970; the 1972

report predicted this would rise to $450

million in 1975. Astronomical growth was projected for the whole industry (see Table

7). The cost of measurement includes the

price of the resolution chart and the cost

of recording its image on the film; at $14

for test charts with a lifetime of say 2 years, the standard costs 2 cents a day.

The cost of measurement is in the processing. Microfilm systems are the end of the

line of product and the beginning of the

line of information service; the value

of those services is considerable.

3.1.3 Societal, Human, Person-on-the-street

Measurement makes possible the design of

optical systems with predicable behavior and

measurement provides for efficiency in manufacture, interchangeability of parts, product

reliability and consumer confidence.

In the prescribing and manufacture of

spectacle lenses, good measurement of refractive power leads to a product which improves

an individuals vision. The benefits are the

comfort, happiness and productivity of the wearer.

In the manufacture of photographic goods,

recision measurement of photographic density

eads to innovation and reliability. The

benefit is a consumer more confident in the

film than in his camera technique.

In industrial radiography, measurement of

transmission density yields radiographic

26
Table 7. Estimated Cost of Medical X-rays

for 1970.

Cost Cost/x-ray'

Cost Component $ millions $

Radiologists' fees 858 2.64

Technicians' wages 702 2.16

Film & development 390 1.20

Supplies & equipment 624 1.82

Overhead 1170 3.60

Amortization 156 0.48

Total $3900 $11.80

1. Estimate, based on Public Health Service,

American Medical Association, and Bureau

of Medical Insurance data, as reported by

a private organization.

2. For an estimated 325 million medical

(non-dental) x-rays.

images that tell something about the structural soundness of parts. The economic

benefits are reduced processing of inherently

faulty materials, improved workmanship, and

product reliability. The societal benefit

of structurally sound civilian and

military aircraft is lives saved. Similarly,

in medical radiology, a benefit is the

early detection of a faint shadow on a lung.

Finally, advanced measurement techniques

in lens testing and image analysis contribute

to innovations in the design of optical

systems and improved control in their manufacture. The benefits are an earth re- sources satellite camera which gives information on crop conditions, weather forecasting, ocean currents, mineral deposit

formations; and photoreconnaissance systems,

which give intelligence data on strategic

weapons deployment and tactical troop

activity.

3.2 Status and Trends of the System

Were it possible to convene a session of

standards committee chairmen and members, em- ployees of the regulatory agencies involved,

manufacturers of photographic goods, instrument makers, workers in the field of imaging

optics, and market analysis, a synopsis of

their judgments and opinions might sound

like this:

Photography: In terms of ordinary film

processors, current ranges of density on photographic tablets are fine. They have,

however, problem with low photograph densities; commercial densitometers use opal

glass in the light collection system instead

of integrating spheres. This results in

small discrepancies between what the instrument reads and what standards calibrated with

the other method say. A draft ANSI standard

to update PH2.19 gives equal status to both

methods. New primary calibrated standards

are required. The photographic manufacturers

need an extension of the range of standards

to higher densities with better precisions

at the lower. Projections for industry

rowth as given in a private market survey

Predicasts, Cleveland, 1972) show total

industry sales growing from $4.4 billion in

1970 to $16 billion by 1985.

Radiography. The present range and precision of photographic densities meets the

current and expected needs of radiographers

in general: A Standard Research Institute re- port predicts that the resolution and sen- sitivity levels now demanded in critical

industrial radiography will become industrywide practice by 1980. The use of radiographic NOT is expected to grow rapidly;

the photographic market survey mentioned

above projects industrial x-ray equipment

and film sales to rise from the 1970 level

of $65 million to $150 million in 1980. In medical radiography innovative practices are being introduced. Microfilming of radiographs for record keeping has begun; it is not thought that the microfilm images are

being used for original diagnosis or re- evaluation. Were this to be done, it would

facilitate "packaged" medical histories,

including radiographs, which follow a patient

as he moves geographically. Advances in

digital and optical (Fourier transform) com- puter technology, combined with techniques

derived from aerial reconnaissance optics,

has led to a system for machine reading of

medical radiographs. It has been asserted

that if preliminary evaluation of x-rays be

machine could reduce by 50% the time required

for a physican to scan a chest x-ray, a savings to society of $75 to $200 million

could result (see Table 9 for calculation

and source). The 1970 sales of medical x-ray

film and equipment amounted to $305 million

with $585 million anticipated for 1980

(Table 8).

Graphic Arts. People in this industry are getting by on what reflection density standards are available. Their needs are mixed;

some need a true grey scale (black and

white), some need color tone scales. A study of reflection densitometers as used in

the gravure printing industry (Miles Southworth, Gravure Technical Association, 1972)

showed they performed well; he pointed out

that reflection standards were not available

from NBS. A recent development in the in27
dustry is the introduction of the Universal

Product Code which allows machine-readable

package labels for use with automated pointof-sale equipment. At least one photographic

company sells reflection chart standards for

UPC printing control. The retail associations are mixed in their feelings about

the need for technical support from the

federal government. Graphic arts photographic

equipment (process cameras and phototypesetters) are expected to rise from $67 million in 1970 to $335 million by 1980; in the same period, photocopying equipment revenues

(purchases, rental, lenses) have been predicted to go from $1.1 billion to $2.6 billion (Table 8).

Miorofilm. Industry people are happy

with the Microcopy Resolution Chart itself,

but not too happy about its price. The range

of spatial frequencies is more than adequate.

If the medical people start microfilming

radiographs in any numbers, the volume of users could increase. A recent development:

the draft ISO standard which gives coequal

status to the NBS Resolution Chart and the

French Mire Target is nearing adoption. At

present, only the French Chart has official

status. The Mire chart has been touted as a superior test of legibility but a British

Standards Institute worker has given substantial technical evidence to the contrary.

(The British Standard, BS4310-2. 1-1970,

specifies the NBS Microcopy Chart as a standard)

A new development in automation of

microfilm systems is the Computer Output

Microfilm (COM) system. COM system consist

of a cathode ray tube display and a high

speed microfilm camera. They can transfer

data from magnetic computer type onto

microfilm at a rate of 90,000 characters

per second. The Navy Printing and Publications Service has a COM system worth

$250,000 that handles 5 million pages of

data per year. COM equipment sales were

30% of microfilm equipment sales 1970

and are expected to approach 70% by 1985.

Primary microfilm equipment and film sales were $280 million in 1970 with a projected

increase to $1.3 billion by 1980 (Table 8).

Lens Testing. Two documentary standards,

ANSI Z80.1 and Z80.2, apply to prescription

lenses. Manufacturers and dispensers have

available to them the means to execute the

provisions of these standards. The formation

in 1971 of a committee under the auspices of

ANSI PH3.2 on Photographic Apparatus has not

resulted in a written standard on lens

testing. One producer of medical and industrial x-ray units describes the effect of

this situation of his operations; 80% of

the units he manufactures have CRT displays

with lens systems and image intensifiers ; he

buys the lenses from two foreign firms and

tests them with MTF equipment from a third;

he adds that the MTF device has become his

standard. A somewhat bewildered physician

reports that he can find no documentary

standard or test standard for evaluating the

microscopes he procures for a medical re- search lab. Since the resolution limit of

a microscope may be as high as 2000 c/mm

and non-silver halide photographic materials

with resolution limits above 1000 c/mm

are available, there is room for progress

in this region of testing and standardization. Sales of passive optics (lenses,

spectacles, binoculars, etc.) have hovered

around the $500 million mark for a few years.

Optical microscopes advanced in sales from

$10 million in 1969 to $15 million at the

present.

Table 8. Approximate Values of Shipments,

of Some Optical & Photographic Equipment.

Shipments

($millions)

1970 1980

6 35

66 150

67 335

190

280 1275

305 585

500

548 1224

1072 2860

1090 2610

Products

Densitometers & allied

devices

Optical test equipment

Industrial x-ray

Graphic arts

Ophthalmic lenses

Microfi Im Medical x-ray

Optical lenses & instruments

Motion picture

Still picture

2 Photocopy equipment

1. Data for optical equipment based on Department of Commerce figures cited in

the text; no 1980 projections included.

Photographic film and equipment data based

on market survey by Predicasts, Inc.,

Cleveland, 1972.

2. Includes sales, leases, and rentals.

The growth part of the industry is involved

with active devices in which the image is observed not by a human eye but an electronic

detector: such systems as optical character

readers used at present in sorting mail,

read-heads for point-of-sale computer systems now in use in supermarkets, and

"optical computers" which analyze images such

as in the automatic chest x-ray scanner described above and in devices like a finger

print scanner the Federal Bureau of Investigation has acquired. Economic data on these systems is inseparable from the overall optoelectronics market which includes

light sources and detectors. A private

28
survey of this field found shipments of

$106 million in 1972 and projects growth

to $265 million by 1978 (Frost and Sullivan,

Inc., New York, 1973).

Table 9. Effect of the Semi -Automation

of the Examination of Chest X-rays.

Number of x-rays 150 million per year

Rate of inspection 15-30 per hour

Time consumed 5-10 million hours

Increase in rate by,

semi -automation 50%

Time saved 2.5-5 million hours

Cost of radiologists'

time $30-$40 per hour

Value of time saved $75-$200 million

1. Computation reported by a private

organization to the National Science

Foundation.

2. Preliminary selection of radiographs

which have signs of pathology, final

judgment by radiologist.

4. SURVEY OF NBS SERVICES

4.1 The Past

The National Bureau of Standards, an agency of the U.S. Department of Commerce, was founded shortly after the turn of the centory by an act of Congress. Its mission, to provide technical support to industry and

the federal government, is spelled out in

that act. NBS became active in optics

around that time when a worker at NBS did

basic studies of the commercially available

photographic materials. Shortly after

World War I, NBS began calibrations of "airplane cameras" for the U.S. Army. Filters

to reproduce sunlight and daylight in the

laboratory, the so-called Davis-Gilson filters

still in use today, were developed at NBS and

adopted by the International Congress of

Photography in 1928 and the International

Commission on Illumination in 1931. An NBS

worker in the 1930 's introduced the "gamma-bar'

bar" method for film speed classification.

The NBS Microcopy Resolution Chart, initially

intended in the 1940 's for the specification

of federal contract work, became an industry

standard. Work on photoresists and high

resolution microphotography drew scientists

and engineers from every segment of the

electronics industry in the late '50s and

early '60s to discuss the photoetching which

revolutionized the industry and to see the

extremely high resolution camera NBS developed

for testing the resolving powers of photographic materials. The concepts, terminology

and notation for photographic densities to be

incorporated fully in a new ANSI standard were proposed by an NBS worker in the late

'60s.

Since that time, photographic sciences

have been discontinued, aerial camera calibrations have been transferred to another

agency, and program in optics have been

directed toward the application of optics

to problems outside the field. The changes

reflect a general trend at national laboratories, at home and abroad, away from

"optics" in the classical sense.

4.2 The Present - Scope of NBS Services

4.2.1 Description of NBS Services

Traced on an NBS organizational chart, a pointer following lines of management would move down from the Institiute of Basic Standards, through the Mechanics Division,

and come to rest on the Optics and Micrometrology Section, the present home of the

work in imaging optics.

Parts of six people, that currently add

up to 3 1/3 full-timers, work in the field.

One is a voting delegate to ANSI Committee

PH2 which deals with sensitometry in general

the same person is a technical representative

on PH2.19 which developed the new standard

on photographic diffuse density now under

consideration by PH2. Another person is on the ANSI PH2 Work Group on Microdensitometry

and a third on a PH3 Task Force on Optical

Transfer Function; these latter groups are

doing the spadework on the development of

standards in their respective fields of

optical system testing.

The important measurement instruments at

at their disposal include:

*an inverse square bar (see section

2.2.2) for the fundamental measure- ment of photographic density and the

primary calibration of transmission

density standards; the device operates over the range of densities 0 to 4.25 with accuracies of 0.005 or 1/2

percent which ever is greater.

*two commercial transmission densitometers for the transfer of densities

to secondary standards. One model

uses an integrating sphere for light

collection; the second, which digitally displays densities in the range

0 to 1 to 0.001, uses opal glass.

The range of both instruments compares

with the range of basic measurements;

they transfer measurement with a re29
suiting accuracy of 1%. *a commercial reflection densitometer

used to compare secondary standards to ceramic plaques which require calibration outside the section. The range

of the densities on the plaques is 0 to 2.33, with accuracies or +0.01 or

2%.

*a wavefront shearing interferometer

(WSI) developed in the section, for

testing lenses and lens systems; the WSI

currently yields on-axis monochromatic

pupil function, MTF, OTF, and maximum

aberration measurement for optical devices with f numbers above f/2; in

spatial frequencies, its range of mea- surements for the first three quantities

is 0 to 2000 c/mm. Aberrations are measured with repeatabilities of 0.03

of the wavelength of light.

*four commercially produced scanning

microdensitometers for the evaluation

of photo images; one has automatic

scanning and is interfaced with a computer and magnetic tape system. It has the capability to resolve density

differences of the order of 0.001, to record data derived at intervals on the

film of 1 micrometer, and to resolve up

to 200 c/mm.

*plus measurement microscopes for the exam- ination of microcopy resolution charts,

the usual light sources, collimators and

optical benches used for refractive power

measurements, and MTF instrument and a Twyman-Green interferometer (both non- commercial) for general lens testing,

and the assorted hardware and optical

components associated with interferometry

and optics in general.

The devices are the basis for the calibration of the standards which NBS distributes:

*SRM 1001 - a double emulsion blue-based

x-ray film tablet with transmission densities from 0 to 3 in 21 steps.

*SRM 1008 - a single emulsion neutral grey

photographic tablet with densities from

0 to 4 in 21 steps.

*SRM 1009 - a tablet similar to the 1008

with densities from 0 to 3. *SRM 1010a - the NBS Microscopy Resolution

Chart, with 21 patterns with spatial frequencies ranging from 1 to 18 cycles/mm.

Density standards, both reflection and

transmission, submitted by users are also

calibrated. Similarly, lenses sent to NBS are calibrated for focal length and re- fractive power or tested for wave-front

properties as requested. Density measurements conform with the basic definitions

given in ANSI PH2.19 and, through these,

with ISO specifications; the microcopy

resolution chart, designed by and manufactured for NBS, is the domestic industry standard and is in the process of

becoming an ISO standard; no documentary

standards define lens properties or specify

the means of their measurement.

Besides routine calibrations, the people

and the equipment are involved with activties directed toward improved standards and

standard measurement techniques:

*A new primary calibration facility, based

on a novel approach to the measurement of

photographic density, is being developed

which will extend the range and increase

the accuracies of the transmission density

standards NBS provides.

*The WSI with its proven capabilities for

easy and precise lens testing is being

tailored for use on a variety of optical

systems and its computer system for

data acquisition is being implemented.

*Physical standards for testing the dimensional - measurement properties of optical

and electron microscopes are being developed; a supportive study of the effects of

eyepieces and stage illumination of light

microscopes on these properties is being

made.

*Special prototype artifacts for the evaluation of high performance photographic

and optical systems are being produced;

along with the production of the artifacts,

the theory related to their use and to optical performance testing in general

is being analyzed and applied.

The purposes of these projects are dual in

nature. In a limited sense, they are to provide physical standards and measurement

services and to maintain the requisite com- petence. In a broader sense, they are to fulfill parts of the overall NBS mission;

namely, to aid industry in general and to satisfy the measurement needs of federal

agencies.

In the field of imaging optics, NBS provides physical standards directly to individuals and private organizations who have

one or both of two reasons for acquiring

them; first, to satisfy a desire to refer

their measurements to an objective, com- petent and authoritative source; second, to satisfy the requirements of federal agencies

with whom they do business or which re- gulate them: specifically, DOD, NASA, AEC, FAA or DOT. (See section 2.4.4). NBS

measurement services outside the provision of standards are used by private

organizations which act from the first

motivation.

The standards, testing and consultation

which NBS provides to federal civilian and

military organizations similarly falls into

two categories; that which is needed in

matters of procurement and that which is

needed in matters of mission. Specific

details of the relationship of private

30
and governmental organizations to NBS

standards and measurements will be analyzed

in section 4.2.2, where users are identified.

The output of NBS in imaging optics is varied. In round numbers, 10,000 microcopy charts are distributed annually and

200 photographic density step tablets; 40

or so density standards submitted by users

are calibrated; 2 or 3 primary calibrations

of transmission density are performed for

users as well as 2 or 3 reflection density

cal ibrations

Conventional lens testing declined

sharply with the transfer of camera and

photographic lens testing facilities to the

U.S. Geological Survey. A series of papers

consisting of 12 or so journal articles and

10 NBS technical notes on interferometric

lens testing, the theory of diffraction and

interference effects in optical systems, and

microdensitometry (leading to a recent

article on state-of-the-art measurement and

theory), laid the groundwork for the interferometric lens testing service introduced

in fall of 1974.

The benefit of this activity in optical

testing has gone primarily to civilian and

military agencies. Ten interferometers

were fabricated for an AEC prime contractor,

extended consulting and in-house testing of

optical systems have been done for others.

A handful of lenses and sets of lenses

from private companies have been received.

Information transfer to and from NBS, independent of this study, has been via the

standard committee activities, the scientific journals and meetings, and in-depth

study of the optical measurement requirements of the semiconductor industry (part

of a larger Advanced Research Projects

Agency study of their overall needs),

attendance at three concentrated academic

courses in optics, a training course provided by NBS to users on the theory and

practice of microdensitometry, interaction

with the Council on Radiation Measurement

(an NBS sponsored users group) as well as the usual give-and-take between NBS and the users of its services.

4.2.2 Users of NBS Services

NBS records show that in one eighteen

month period, 300 photographic density standards were distributed: 39 to manufacturers

and service companies in photographic and

graphic arts production, 189 to firms doing

industrial NOT, 21 to government agencies,

and 51 to users in assorted fields as shown

in Table 10, Three received primary calibrated standards: a photographic manufacturer, a maker of densitometers and a defense

agency.

In a period of the same duration, nearly

15,000 microcopy resolution charts went to about 200 organizations: 13,200 to private

commercial and institutional users and 1800

to government agencies. In 1973, 30 domestic

suppliers of microfilm, microfilm equipment

and photocopiers received 60% of the charts;

one of these companies also distributes

charts it receives.

For a similar 18 month period, 10 WSI

interferometers, designed and fabricated by

NBS, were shipped to an AEC prime contractor:

a set of 100 or so master test lenses were calibrated for an ophthalmic goods manu- facturer; a set of four for another; a $20,000 lens was tested for a federal law

enforcement agency; a similar lens for a semiconductor manufacturer; special sine wave and edge targets were supplied to 15 companies and a number of special studies were performed for federal agencies. In the period 1971-4, these included:

*the evaluation of a $2 million microfilm

system the Patent Office was in the process of procuring; the testing resulted

in the settlement of a dispute between

that agency and the manufacturer of the

system over the performance specified by

the contract; happily, the system was show to perform properly

testing for the Postal Service of binoculars sold by mail to determine the

possibility of fraudulent advertising

of the binoculars' performance capabilities

provision of test materials and consultation in a law enforcement program study

of the correlation of the 'identifiability' of persons in photographs with

machine-measured characteristics of the

photographs (NBS Report LESP-RRT 0303.00)

*the evaluation of the optical system which

NIOSH (see section 2.4.4) uses to monitor

the output of manufacturers of safety

goggles and eyewear

consultation on the specification of telescopes and image intensifiers for a system

of remote visual observation of Postal

Service trucks during loading and unloading

(NBS Report 10-967)

the redesign and testing of a commercial

terrestial telescope for a civilian

intelligence agency

extensive analysis of the operation of a microdensitometer being procured by the

Department of the Air Force, including

development of performance specifications,

supply of test materials and the overseeing of testing

confidential design work and testing of a special photographic printer which was in

the process of being developed by a vendor

for a government security agency

31
extended consultation on some securityclassified programs of the defense department which involve high performance

optical systems, their design, specification, evaluation and use *the provision of standards and consultation to the FDA's Bureau of Radiological

Health for their program of monitoring

the performance of medical x-ray image

intensifiers

The manufacturers of photographic goods

(See in section 2.5.1, "Photo Industry") are major users of NBS standards. Table 11 shows the nine domestic companies which re- present 97% of film sales and 80% of all

equipment sales in 1970, (Predicasts, Inc.,

Cleveland, 1971); also shown are the two foreign film companies which picked up the

bulk of the 3% remaining of film sales. All

eleven companies (save one photocopier

manufacturer) procured NBS density standards

in the 18 month period; all eleven procured

microcopy resolution charts; seven of the

nine domestic companies have been supplied

with edge and/or sine wave targets. In general, the standards are used on a voluntary

basis: the density standards relate to the

evaluation of film performance and the designation of film speeds on the basis of

revel ant ANSI standards; the microcopy

resolution charts find use in testing re- solution in general

Table 10. Users of NBS Photographic Density

Standards

Product or Service SIC Share

Photographic products 3861 12.4%

Printing & graphic arts 2751 5.8

Aerospace systems 3721 11.8

X-ray & radiation

equipment 3693 10.6

Castings & forgings 3300 8.9

Turbine, boiler,

reactor 3511 6.2

Precision welding 7692 3.7 NDT test labs 7397 6.5

General research 3.5

Other 16.5

Government agencies 11.3

Foreign consumers 2.7

100%

Organizations which purchased NBS photograhic density standards in the period

6/71 to 12/72, grouped according to their

product lines as described in the Thomas

Index of Manufacturers.

1. Share of the NBS standards delivered

in the base period.

The second major class of density standard

users are those involved in radiographic NDT. (see "Metal Products" in section 2.5.1).

Table 11. NBS Standards by Kind Supplied

to the Major Manufacturers of Basic

Photographic Products.

Major U.S. Photographic Calibration Items Product Manufacturers Received from NBS

Co. Sales Products Den. Resol . Spec.

($mllns) Film Equip. Stds. Chrts. Trgts.

A 1200 * * * * *

B 1000 * *

C 350 * * * * *

D 350 * * * *

E 190 * * * * *

F 150 * * *

G 150 * * * *

H 75 * * * *

I 70 * * * * * / * * * *

k2 * * * *

1. According to the market survey from

which the economic data is taken (Predicasts, Inc., Cleveland, 1972), the first

nine companies represented 97% of film sales

and 80% of overall photographic equipment

sales.

2. These companies are the major foreign

suppliers to the U.S. film market.

3. Based on NBS internal records.

This group included, among others, for the

18 month period:

*the "big five" manufacturers of nuclear

reactors

*5 of 6 manufacturers of commerical passenger and cargo transport aircraft

*all 8 aircraft turbine engine manufacturers

*all of the makers of airframes and rocket

engines for the 62 missile systems produced

in 1973 (Table 12)

*all of the makers of the military and

civilian space vehicles and launchcraft

*two prime contractors of nuclear ordnance

*a major shipbuilding installation

*plus a distribution of NDT test labs,

casting and forging producers, and related

32
firms.

The relation of these industries (except

the security-bound ordnance people) to regulatory agencies has been described in section

2.4.4. In general, they work to AEC, DOD,

FAA, and NASA specifications and require

NBS photographic density standards.

The third major group of users of NBS

measurement services includes the vast array

of companies and institutions which require

evaluation of microfilm systems. These are end-users, not manufacturers (see section

2.5.1 for details). The Microcopy Resolution

Chart is an important standard; it is recom- mended for use by the National Microfilm

Association (NMA) and required by the

military in its applications. These charts

go into circulation at the rate of about

10,000 per year and are used by the whole

spectrum of people who record things on microfilm; from libraries, retailers, in- surance companies, and banks to a religious

group which records the genealogical histories of its members. (For the applications

of microfilm and the major users, see section

2.5.1; for documentary standards, 2.2.1.2).

Since the needs of the photo companies

with respect to measurements was known to NBS (via an NBS-sponsored users group) and

since the needs of the microfilm users are voiced by NMA, a survey was made of a limited

group of users of NBS measurement services:

the domestic industrial manufacturers which

appeared on NBS customer lists for photographic density standards in the 18 month base

period, 145 firms in all. Over 25% of the

firms replied to a questionnaire dealing with

their operations (see Appendix A). The percentages of the 37 respondees involved

in NDT and in graphic arts and printing is

comparable to the percentages for the entire

group as already shown in Table 9, roughly

86% to 14%.

Those surveyed were asked how many densitometers they owned, how many people used them

for how many hours per week, what their investment in measuring equipment was, and how

much product was effected by the standards

NBS supplied. Profiles of nine companies

which answered these questions more or less

fully appear in Table 13. Generalization is impossible: anywhere from 1 to 5 densitometers in a company control "dollar volumes

of product affected by the calibration

service" ranging from $120,000 through $25

million to "many" millions.

One question that all 37 companies answered

dealt with why they bought items from NBS:

all the NDT people said they were required to,

all the graphic arts, printing and photo

people said they wanted them for their own production control. On the adequancy of the

standards, the NDT people said fine (except

for three who need a different kind of x-ray

standard now available from NBS): the

graphic arts people have trouble with vesicular film (for which standards are not now

available.

Table 12. Users of NBS Photographic Density

Standards Involved in the Production of

Strategic and Tactical Missile Systems.

Some representative combinations of the

program contributors and manufacturers

of the airframes and engines of the U.S.

missiles listed in the Aviation Week and

Space Technology, Forecast and Inventory Is- sue of March 1973. All the companies listed

but two procured NBS density standards in

the 18 month period for which NBS records were examined; the two were explicitly mentioned as customers of testing laboratories

which use NBS standards.

Prime Contractor

/Program Manager

Beech

Bell Labs

Bendix

Boeing

Emerson

Gen Dynamics

Goodyear Aero

Honeywell

Hughes

Lockheed

LTV Aerospace

Martin-Marietta

McDonnell

Maxson Electron

North American

Phil CO Ford

Raytheon

Sperry Rand

TRW

Western Electric

Subcontractor/Contr i butor

AMP

Martin-Marietta

Altamil

Lockheed

Honeywell

Aerojet

Thiokol

Thiokol

Thiokol

North American

Hughes

Thiokol

Thiokol

Pratt & Whitney

Thiokol

Boeing

McDonnell

Hercules

Bendix

Hercules

Hercules

GE

Aerojet

Hercules

The best answer to the question of how NBS

services related to the end products came from a self-described "small printer"

doing $250,000 a year in business, with

$175,000 in valued-added that is related

directly to measurements. He buys NBS

standards because he wants to and says "we sleep better at night, just knowing you are there."

The direct and indirect effects of NBS

measurement services have been illustrated

in section 2.5.3 on "Major Users" in the

measurement system and section 3.1.2, "Impact

of Measurements." In general, photo companies

have an objective third-party for density and

resolution standards, manufacturing and ser- vice organizations can get the standards they

33
Table 13: Profiles of the Measurement Operations

of Some NBS Density Standards Users

Company

Pseudonym

Densitometers

(units)

Measurement

Personnel

Instrument

use (hrs/wk)

Capital

Investment

($1000)

Product

Affected

($1000)

NDT Test Laboratory 3 3 4 1.3 120

Small Printing Company 1 3 low 250

NDT Test Company 1 4 5.0 300

Instrument Company 3 3 2.1 480

AEC Prime Contractor 4 6 6 5.0 1000

Casting Manufacturer 2 2 5 .75 1500

Metal Fabricator 1 3 3 4000

Turbine Part Maker 3 15 10 2.0 25000

Microfilm Product Firm 5 6 720 many

need for dealings with the federal government,

spectacle lens manufacturers have a source

of measurements which has technical status,

and almost everybody comes out ahead on the

deal.

4.2.3 Alternate Sources

A photographic company (SIC 3861) and a densitometer manufacturer (SIC 3861) are

known to have facilities for fundamental

measurements of photographic density; they

both provide standards to customers. A photographic company makes the Microcopy

Resolution Charts for NBS who checks them for

comformity to design specifications. A few

high technology optical companies (SIC 3831)

have somewhat similar lens test capabilities.

The photographic company and the densitometer

manufacturer refer their measurements to NBS;

the optical companies speak to NBS. Where

users need measurements, these alternate

sources either provide or are attempting to provide for their needs.

4.2.4 Funding Sources for NBS Services

The costs to the users of NBS services

are based by Congressional mandate (Title 31,

U.S. Code, annotated, section 483(a)) on the

full cost of the performance of those ser- vices. As implemented by Department of

Commerce guidelines (DOC Administrative Order

No. 203-5, revised) that cost includes:

*direct costs (supplies, labor, accrued

leave factor, personnel benefits, etc.),

*direct supervisory costs

*overheads (including depreciation, maintenance, etc.)

*and cost of space.

As a result, prices are not based on what an economist might call "price-quantity relationship in the market structure"; that is, not

on what the market will bear but what it costs

NBS to supply the services (Tables 14 and

15).

Prices do not include the cost of development of the measurement capabilities; the

tax payer handles that. Money flows by Congressional appropriation from the Treasury,

through the Bureau of the Budget, through

Commerce, down the NBS organization to the

imaging optics program where it appears as equipment and salaries - Governmental agencies

pay for the services they get from NBS on a contractual basis (for extended projects) or

an any other user would for short jobs or standards.

In fiscal year 1973, $27,000 worth of

microcopy resolutions charts were sold,

$11,500 worth of photographic step tablets,

and $4,000 worth of density calibrations were

performed on samples submitted by users. Of this $42,000, $12,000 returned to the

section in STRS money. Total STRS money;

$197,000; other agency money, $118,000;

direct calibration fees, $4,000; total

operating budget in 1973, $319,000.

4.2.5 Mechanism for Supplying Services

The bulk of measurements are dispersed via

Standard Reference Materials as described in

the Special Publication, NBS SP-260. The

Office of Standard Reference Materials (OSRM)

contracts for the manufacture of photographic

34
density tablets and microcopy resolution

charts, receives them, gives them over to the Optics and Micrometrology Section for

calibration and, on their return, puts

them up for sale as: SRM 1001 Double-emulsion, blue-based x-ray

photographic step tablet, 0 to 3 density

SRM 1008 Single emulsion, neutral grey

tablet, 0 to 4 density

SRM 1009 Similar to 1008 but 0 to 3 density

SRM 1010a The NBS Microcopy Resolution

Chart (known to industry as NBS

1010a).

The original manufacturer of the SRM 1010a

happens to buy back about 60% of them and

distributes them as a "service to customers."

Primary calibrations of transmission

density standards, secondary calibrations of

reflection and transmission density standards,

measurements or testing of lenses, and

similar conventional measurement services are described in NBS Special Publication, SP-250.

All prices are based on cost-recovery as described in section 4.2.4.1. On the basis

of what appears in SP-250, NBS does not do

conventional lens testing; it gave that

facility over to the Geological Survey. How- ever, manufacturers of ophthalmic goods and

measuring instruments have requested NBS

"certification" of their master lenses; the

lenses are, therefore, tested and reports

issued.

Besides the general communication activity

described in section 4.2.2, the measurement

services in optical imaging have recently

included an announcement of the new lens test service before its inauguration by a 300 letter mailing to potentially interested

parties, the publication of an NBS report

(NBSIR 10970) on densitometer calibration

which outlines a. useful computer program,

a course at NBS on microdensitometery for users of the devices, a series of guest

lectures at graduate and undergraduate levels

for a university with an optics program, a description of services regarding reflection

microdensitometry to a retailers' symposium

on the use of the Universal Product Code

(UPC), and, unrelated to the study upon

which this report is based, direct contact

with densitometer manufacturers, optical

companies, defense agencies and general users.

An attempt to schematically represent how

NBS fits into the system is shown in

Figure 6. The sources of information

flow into NBS and the measurement services

flow out of NBS is given in Figure 7.

4.3.1 Economic Impact of Major User Classes

Some of the more obviously interesting

and practically unanswerable questions

Table 14. NBS Revenues in FY-1973 from

Fixed-Fee Services.

Measurement Service Items Sales

Microcopy Resolution

Charts 10,650 $27,000

Photographic Step Tables 182 $11,500

User-submitted Tablets 40 $2,475

Inverse Square Calibrations 2 $1,400

Reflection Calibrations 2 $125

Table 15. Cost-to-NBS Basis for Sales

Price of Photographic Standards in FY-1973.

SRM 1008 Materials & handling $44.00

Cal ibration 28.00

Sales price 72.00

SRM 1009 Materials & handling $39.10

Cal ibration 18.90

Sales price 58.00

NBS 1010a Materials & handling $2.02

Cal ibration 0.72

Sales price 2.80

about measurements in imaging optics deal

with their ultimate value in dollars and

cents. The best answers require some form

of "incremental analysis" by which the

economic effects of a change in some aspect of measurements (e.g., frequency,

precision or accuracy) are traced through

the manufacturing process to the end

product, the marketplace and the consumer.

Such analyses have proven to be beyond

the scope of this work. Rather, the

"economic impact" of measurements will

be discussed in terms of the economic

dimensions of some of the industries

involved, and the relationships of mea- surements and NBS services to the output

of these industries.

In 1970, eleven firms manufactured

virtually 100% of the photographic film

marketed in the U.S. that year. An essential part of the manufacturing process

and the performance rating of the film

is the measurement of photographic densities,

The common bases of measurement among

the eleven firms were the NBS standards

each procured. The total value of the

film marketed by these companies in 1970:

$1.3 billion; the size of the overall

35
CORM

1

ISO

DENSITY STANDARDS

!

DENSITOMETER MANUFACTURERS

NBS

SRM PROGRAM

PHOTOGRAPHIC

STEP TABLETS MICROCOPY

RESOLUTION CHARTS

OS A

PHOTOGRAPHIC

INDUSTRY MICROFLIM

INDUSTRY

USERS

DOD

I

FEDERAL STANDARDS MIL SPECS

\ T OPTICAL INDUSTRY

USERS

J L

USERS J L

DENSITOMETRY RESOLUTION

CALIBRATION CONSULTATION

LENS TESTING 4 MICRODENSITOMETRY

PAPER STANDARDS SALES

Figure 6: NBS and the Measurement System

photographic market the film supported:

$4 billion.

In 1973, five firms were the major

producers of nuclear reactors for electric

power generation, research and defense.

The Nuclear Regulatory Agency (formerly

the Atomic Energy Commission) enforces

mandatory radiographic inspection of

critical reactor components during their

manufacture. In the course of a radiographic inspection of a reactor part, a photographic density standard is used to calibrate the instrument which monitors

the density of the film image. All five

manufacturers of reactors in 1973 procured

and used NBS density standard. For the

period 1965 to 1973, contracts for con- struction of new reactors averaged about

$8 billion per year.

In 1973, the aerospace industry produced over 16,000 aircraft as well as an unspecified number of military and civilian

spacecraft and launch vehicles. The

Federal Aviation Agency, the Department of

Defense, and the National Aeronautic and

Space Agency have mandatory procedures

for the radiographic inspection of aircraft and spacecraft. Again, radiographic

inspection involves the use of photographic density standards. In 1973, five

of the six manufacturers of commercial

passenger and cargo transport aircraft, as well as all of the manufacturers of aircraft turbine engines, missile system

airframes and engines, and military and

civilian spaces vehicles and launchcraft,

procured and used NBS photographic density

standards. The value of the air and

space hardware produced by the aerospace

industry that year was $12.2 billion.

In 1970, medical radiologists performed an estimated 325 million diagnostic

x-rays on 110 million patients. The FDA's Bureau of Radiological Health monitors

performance of medical x-ray receptors

by evaluating film-screen combinations.

A well -characterized receptor allows a doctor to obtain a good x-ray picture at a lower level of potentially dangerous

radiation to the patient. The BRH uses an NBS-constructed instrument to expose films

and an NBS density standard to evaluate

them. The market value of the medical

x-ray film consumed in 1970 was over $200

36
iNRjr

GOVERNMENT

GSA

USAF*

MIL Specs

Defense Agencies*

NBS/Standard Reference Materials*

NBS/Institute for Apolied Technology

JOURNALS

Opti k Appl led Opti cs Optics Acta Popular Journals

Industry News Journal of Optical Soc. of America

Journal o-^ Soc. of Photographic

Scientists and Engineers

INDUSTRY

Itek* Perkin Elmer

Kodak* Pratt-Whitney

Macbeth* Council on Optical

Polaroid Radiation Measurement*

STANDARDS GROUPS

International Standards Organization

American National Standards Institute

American Society or Testing & Materials

SOCIETIES & INSTITUTIONS

Univ . 0- Arizona

Univ. of Rochester

Optical Society of

American Institute

National Microfilm

America

of Physics

Association

Society of Nondestructive Evaluation

Univ. of Rochester Institute of Optics

Soc. of Photographic Scientists & Engineers

OPTICS

GOVERNMENT JOURNALS

AEC HEW NOAA USN

USAF* NASA

Defense Dept.* Patent Office

Postal Service U.S. Health Ser. Navy Publications

Journal of Engineering

Journal of Optical Soc. of America

Journal of Society of Photographic

Scientists & Engineers

NBS/IAT (Law Enforcement)

NBS/Standard Reference Materials*

NBS/Scanning Electron Microscope Fac.

INDUSTRY NDT Labs

Microfilm Users

Film & Camera Producers

Densitometer Manufacturers

Printing & Graphics Industry

X-Ray Equipment Manufacturers

Council on Optical Radiation MeasurementCasting, Reactor, Boiler, Turbine,

Vessel Mfg.

30^7

STANDARDS GROUPS

IS0/TC47"

ANSI/PH2

ANSI/PH2/28-

ANSI/PH3"

Figure 7: Input-Output Chart for NBS Programs in Optics

37
million; the portion of the health care delivery system devoted to medical

radiology has been estimated at over $4

billion.

In 1970, over 100 million square feet

of microfilm, the equivalent of over 10

billion frames in 35 mm format, were

used in the U.S. for recordkeeping purposes. The standard means of evaluating

the reproduction quality of mi orographic

film, cameras and readers involves the

measurement of resolution by means of

a microcopy resolution chart. NBS, the

sole source of the industry-recommended

resolution charts, supplies over 10,000

to users annually. The value of the

microfilm sold in 1970 was over $100

million; the microfilm market as a whole amounted to over $600 million.

Other statistics for industries

using NBS imaging optics standards in

the areas of radiography, graphic arts,

and ophthalmic lenses are given in

section 3.1.2.

4.3.2 Technological Impacts of NBS Services

The technologies supported by the standards which NBS provide are mature. The

development of new photographic products are basically matters of photographic

chemistry; the density and resolution

measurements are tools to evaluate them.

The development of new lens and lens

systems is a matter, it seems, of refining

the old ideas. The standards, therefore,

keep the photographic and optical industries

tuned.

The moving technology supported is that

of high performance optical systems; it may

take a while but the principles of physical

optics embodied in the theoretical and

analytical studies of these systems now being done will feed down from the production of high technology devices into consumer optical productes and instruments,

like automatic x-ray image analyzers, which

effect the consumer.

4.3.3 Pay-off from Changes in NBS Services

In the distant past, changes in NBS

services related to the inauguration of a program in camera testing and photographic

sciences produced:

*a camera testing capability which led to the development of federal and state

specifications on land survey aerial cameras

*the daylight filters which became international standards and are still is use *the "gamma-bar" technique which became

an industry practice for the assessment

of film speed

*the microscopy resolution chart which

was adopted as the industry standard.

In the past decade, modifications in

NBS calibration services have produced

the following results:

*In 1963, the old microcopy chart was redesigned with spatial frequencies

based on an ISO preferred number series

and, in 1967, five more spatial frequencies added. The combined effect

was the NBS 1010a which is becoming a formal ISO standard. The result is a domestic standard by which microfilm

manufacturers can satisfy the needs of

foreign and domestic customers.

*In 1974, a new photographic density

standard, the SRM 1001, was introduced.

Consisting of a blue based, double

emulsion film, the SRM 1001 satisfied

the needs of radiographers for a complement to the neutral gray, single

emulsion standards already available.

The result for NBS was a reduction in

the number of special calibrations

required of it.

*In 1971, the aerial camera calibration

facility of NBS was transferred to the

U.S. Geological Survey. The development of such testing had reached a zenith a decade ago and measurements

had become routine. Transfer of the

operation to the Geological Survey

resulted in no loss of benefit to the users of the service. While con- ventional lens testing went with the camera calibration, some companies like

ophthalmic goods manufacturers request

that NBS perform this service for them;

they receive such service. In fall of

1974, NBS supplemented the lens evaluation services available through

federal laboratories with an interferometric lens testing service described

in Special Publication, SP-250.

For about a decade, NBS facilities for

the measurement of photographic densities

have been maintained on a status quo.

Reflection density reference standards and

densitometers have not been upgraded re- cently and calibrations for users have

dwindled to a scant two or three per year.

While in regular use, the transmission

density calibration facility has not kept

pace with industry practice in fields outside radiography. Commercial transmission

and reflection densitometers which exceed

in range and precision those of NBS calibrations are on the market. Densitometer

manufacturers and their more measurementintensive customers are seeking better

calibrations from NBS. Improvement of

NBS capabilities would result in benefits

to manufacturers of photographic film and

equipment, photocopiers, densitometers.

38
and, indirectly, to the consumers of

these products.

It is possible that continuation of the

status quo at NBS would result in a decline

in the number of standards calibrated.

The order in which users would find NBS

standards insufficient to their needs depends on the nature of the need: whether

the requirement is for hard measurement

information, a pro forma reference to an authoritative source, or a talisman to fulfill government procurement

specifications

,

4.4 Evaluation of NBS Program

Basic capabilities. In transmission

densitometry, the primary calibration device,

the inverse-square bar, yields precisions and

operates over a range of transmission

densities which do not compare with measurements currently being done in the photographic industry or which can be measured

with commercial densitometers. Further, the

light collection system is capable of measuring only one of the two types of transmission density to be given equal status in

the ANSI standard, PH2.19, now in the final

stages of adoption; the type of density measured by NBS is not the type which is measured

by prevelant commercial densitometers. A new densitometer, recently procured by NBS, measures this 'opal density' and has a precision

at low densities which is greater than the

accuracy to which NBS can calibrate its own

standards. Because of the relation of the

precision of these instruments to the

accuracy of NBS standard, users have reported

that they believe they cannot exploit the

instruments full capabilities.

In reflection densitometry, the basic

reference standard is a set of plaques

which were calibrated by the old Colorimetry Section of NBS; the reference

standards need replacement. The reflection

densitometer is antiquated.

In lens testing, the wave-front shearing

interferometer, WSI, which was developed at

NBS, is capable of operation with precisions

that fulfill the requirements of the most

demanding users of optical testing and over

a range of spatial frequencies which sur- passes commercial testing devices, most

prototype devices, and the resolution

limit of every optical system except the

finest quality microscopes.

In microdensitometry , the equipment is

first class; the supporting theoretical

and analytical studies of the performance

of microdensitometers , of their applications in image analysis and the testing

of optical systems, and of high perfor- mance optical systems in general, are

state-of-the-art and unsurpassed.

Current Standards and Measurements.

A survey of users of NBS photographic

density step tablets (section 4.2.2)

showed that these standards meet the

current needs of radiographers and,

along with this survey, discussions with

many active in the field of industrial

radiography have led to the conclusion

that the standards will meet the needs

for at least a decade. The standards

are not adequate to fulfill the needs

of the manufacturers of photographic

equipment, photocopiers, and related

products

A cogent statement of these needs has

been given by a special users group founded

under the auspices of NBS. After a series

of meetings at NBS between October, 1971 and

May, 1972, representatives of the optical

radiation measurement community, scientists

and engineers seriously concerned with the

present lack of adequate standards in this

field, were organized into the Council for

Optical Radiation Measurements (CORM) as an activity of the Technical Committee 1.2 on Photometry of the U.S. National Committee of

the CIE (Commission Internationale de L' Eclairage). The report of CORM (Pressing

Problems and Projected National Needs in

Optical Radiation Measurements: A Consensus

of Services Desired of NBS) presents the consensus of CORM on the most urgent problems

in the areas of sources, detectors and techniques and their relative priorities. The

specific details of CORM recommendations with

regard to diffuse visual transmission and

reflection density standards and measurement

techniques represent an extension of the

range, an increase in the accuracies, and

changes in the techniques of NBS measurements.

The recommendations concerning transmission density standards are: *an extension of the density range of

standards provided by NBS from a maxmium

density of 4 to 6. *an increase in the calibration accuracy

from + .005 or 1/2% over the entire range

to + .001 or 1/2% in the range 0 to 3 and

+ .^"2 or 1/2% in the range 3 to 6. *the introduction of the use of opal glass

in calibration measurements.

*a study of the effects of sample geometry

and composition and of measurement techniques on measurement results, including

the relations of opal glass and integrating

sphere techniques, densitometer and inverse-square techniques, and general tablet

parameters and measurement results.

The CORM recommendations for diffuse re- flection density standards include:

*the introduction of a new NBS master arti39
fact standard consisting of neutral , non- fluorescent ceramic tiles.

*an increase in the basic accuracy of re- flection density measurements from + .01 or 2% to + .001 or 1/2%.

The NBS MTcrocopy Resolution Chart, NBS

1010a, meets the needs of industry and users, reports an official of the National Microfilm

Association. A controversy over the relative

merits of the NBS- type chart and the French

Mire chart has prompted a member of the

British Standards Institute (who is also

on the ISO working Group on microcopy quality)

to evaluate the relative performance of each;

he concludes that the Mire chart is "not more

of a test for legibility than the NBS is, and

is inferior in testing resolution" (NMA Journal of Micrographics, Vol. 7, No. 6, July

1974). A draft ISO proposal now in conmiittee

would designate the NBS-type chart "ISO Test

Chart No. 2" and put it on co-equal status

with the presently recommended Mire Chart

which would become "ISO Test Chart No. 1".

The NBS chart will not be formally referred

to in the standard but the specifications

cited are those of the lOlOa. Anyone may

manufacture a chart patterned after the NBS

lOlOa and consumers will not be required to use NBS as a source of an ISO standard target.

The lens testing service derived from

research supported by agencies outside

NBS and became part of NBS measurement

services in fall of 1974. Advance notice

in the form of letters to potential users

has not resulted in utilization of the

service. The most recent Optical Physics

Division Advisory Panel has just suggested

that, except in extreme cases, industry

may be unwilling to pay the cost of measurement; they suggest that NBS might

initiate the formation of a committee

from the optical industry in order that,

by means of the testing of sample lenses,

some level of quality certification might

result.

Programs in-progress . A new primary

calibration facility which will extend

the range and increase the accuracies of

transimission density standards is under

development; based on a novel idea to "cascade" inverse-square measurements,

the system is designed to conform with

ANSI documentary standards and to fulfill the industry needs as described

by CORM. The applicability of the

system to the general problem of detector

linearity characterization will be

determined.

A project to develop a physical

standard for use in the evaluation of

the dimensional measurement capabilities

of optical and electron microscopes as used in industry is under way; a supportive study on the effects of eyepieces and substage illumination on measurements made with optical microscopes

is also being done. The physical standard

and the results of study are important since

optical microscopes are basic measurement

tools in the semiconductor industry and

electron microscopes are daily becoming more widely used as dimensional -measure- ment devices.

A microdensitometry facility is being

developed which will have general utility

in the quantitative analysis of photographic

images and of interferograms which derive

from dimensional -measurement interferometers.

This capability will support NBS measure- ment services in and out of imaging optics

and may become available to users outside

NBS.Rationale and Effect of Services. The

rationale of NBS services and the effect,

if they are successful, is the same: supplying the measurements which facilitate

commerce and fulfill the needs of government

agencies. As presently constituted, photographic density standards provide non- demanding industrial users with a reference

to NBS which they desire for their own purposes or require because of their dealings

with federal agencies. Likewise for

microscopy standards. The lens evaluation

and microdensitometry capabilities fulfill

the needs of defense agencies for an impartial arbiter in procurement matters

and a source of state-of-the-art expertise.

4.5 The Future

To the extent that it depends on the

evolution of presently nascent trends,

the "foreseeable future" of imaging

optics will bring the following developments : Standardization: There will be within the next few years documentary standards

which: place on co-equal status integrating sphere and opal transmission

densities; establish magnesium oxide as the

preferred reference standard for the zero value of diffuse reflection density; define the methods for measuring

the densities of non-silver halide

photographic materials; make the NBS

microcopy resolution chart a formal

international standard; and, possibly,

treat lens testing, microdensitometry

and gravure printing reflection density.

Federal specifications : There may

be regulations governing the performance

rating of medical x-ray film screen combinations, the licensing of radiographic inspectors or commercial trans40
port aircraft, and the effectiveness of

medical devices such as ophthalmic

lenses.

Measurement practices and new tech~

nologies: In photography, factors such

as the relative scarcity of mineral resources will promote the ascendancy of

non-silver halide photographic materials.

Because the light-modulation properties

of these materials are different from

those of conventional film, applicable

measuring instruments and calibration

standards for density measurements will

be necessary.

In radiography, the quest for more guantitative and detailed image information from radiographs will make the use of visual microscopy, microdensitometry and automated image analysis industrial and medical radiographs common.

In micrographics, computer-output

microfilm will play a major role in the

manipulation and mass-storage of recorded

data and will likely be interfaced with

optical character recognition to provide

complete data storage and retrieval systems.

In optical microscopy, emphasis upon

quantitative dimensional measurements

rather than qualitative observations will

push the optical microscope's present limits

of utility and generate pressure for new

optical designs which would extend the

range of application. Better test procedures and calibration standards for

optical microscopes will be sought.

In Fourier-transform and diffraction

optics, the advent of optical -lens

instruments which operate in non-imaging

modes will call for revised lens evaluation

produces, including new measures of proper

lens function as well as reinterpretations of

currently measureable parameters.

* * *

In the light of some of the current and

anticipated needs for calibration standards

in imaging optics, it is recommended that

NBS:continue the development of the primary

calibration facility with its intended

purpose of satisfying users needs in

transmission density measurements.

acquire a new reflection densitometer,

develop suitable primary reference

standards and have them calibrated by

the appropriate NBS group.

maintain the present lens test measure- ment service without further direct investment in it.

continue the program of expanding the

application of microdensitometry into

allied fields, such as the general

evaluation of photographic images

and interferograms

continue efforts to develop a physical

standard applicable to optical and

electron microscope dimensional measurements.

Recommendations for actions when time and resources become available are: determine the appropriateness of and

industry interest in an active users group in the optical industry,

investigate the feasibility and desireability of NBS standard reference materials

for reflection density applicable to graphic arts and related fields.

The means for implementation of these two recommendations are effectively a continuation of the study of users needs. The re- sults of this present study have been:

the definition of the relationship of

NBS to the users of its measurement

services. Little had been known by

NBS of the composition, nature, and

dependency on NBS of its customers,

the discovery by NBS, in the graphics arts industry of a group which are potential

users of NBS services in reflection

densitometry. Since there is no mandatory

dependency on this group at NBS, its use of density standards was unknown,

the knowledge of its users which allows

NBS to place in content the services asked

of it by the Council on Radiation Measurement. the redirection of NBS programs toward

measurement applications of optics rather

than optical testing per se.

5, SUMMARY AND CONCLUSIONS

Generalizations that may be made about

the state of the measurement system in imaging optics of necessity depend on the perspective of the viewer. From the lower echelons of the National Bureau of Standards

organization, the view has resulted in the

following conclusions.

In transmission density measurements, specifically those based on American National

Standards Institute documentary standards,

there is a fairly well-defined structure to the measurement system; basic parameters are well-defined, the methods for the perfor- mance of fundamental measurements clearly

given, the requisite appparatus and instruments available, physical standards commer- cially marketed and obtainable from the

National Bureau of Standards. The accuracies of these standards are generally suitable to user's needs. There are two classes

of dependency on the NBS standards: some organizations in the photographic and allied

industries acquire the standards voluntarilly

in order to maintain control of their production processes; some organizations engaged

in industrial radiographic non-destructive

41
testing obtain the standards to meet the

requirements of federal agencies with which

they do business. The first class of users have called upon the National Bureau of

Standards to improve the accuracies and ex- tend the range of the standards it provides;

an apparatus is under development which will

allow these conditions to be fulfilled as well as to allow a type of detector linearity evaluation not possible on the present

device.

In reflection density measurements, documentary standards are currently under revision to place measurements on a more firm

technical footing and to bring them more in

line with current industry practice. Commercial devices for reflection density mea- surements are marketed and physical standards are available from private organizations. The National Bureau of Standards

does not provide reflection density standards and the quality of its reflection density calibrations is not considered satisfactory to the groups of users which would

normally use the service. Since there are apparently no federal specifications which

require traceability to NBS reflection density standards or calibrations, the question of the responsibility of NBS to supply

these services to users is a matter of

management philosophy. There is a need

within the photographic industry, the microfilm industry, the gravure and lithographic

industries, and other users of reflection

density measurements for improved physical

standards to allow better production control.

In the field of optical testing, the

measurement system is even less well-defined.

Specific groups such as the manufacturers

of ophthalmic goods have documentary standards which govern the measurements appropriate to their operations; testing instruments

and techniques are standardized. The optical industry in general lacks documentary

standards and agreed upon testing procedures.

NBS, in gauging the developments in the industry, made the judgment that the existence

of a documentary standard defining measureable indices of optical system performance

was a prerequisite to the development of a structured measurement system. NBS workers

became active on the appropriate standards

committees working on such standards. A system for the testing of lenses and optical

systems was developed in the course of work

being done for federal agencies and, based

on the anticipated issuance of documentary

standards by the voluntary standards organizations, introduced as a testing service.

Difficulties encountered by the standards

bodies in arriving at satisfactory definitions of testing methods has slowed the progress of those committees and at this time

documentary standards are still in the draft

stages. Based on analogous occurrences in

unrelated fields of measurements, it is

thought that regular use of NBS lens test

services will commence with the formalization of the testing methods as signalled by

the adoption of such standards. In the field

of microfilm resolution testing, the industry

has documentary and physical standards and

gives evidence of smooth functioning. The

role of the National Bureau of Standards in

the operation of this subsystem of optical

testing is well-established and its contributions desired by voluntary users of its

services and required by others.

Market projections made by private firms

in the second year of this decade projected

1980 levels of consumption of amateur and

professional, microfilm, medical and industrial x-ray, and graphics arts supplies and

equipment which are multiples of consumption

in the present period. These projections

imply similar increases in demand for photographic density standards and microcopy resolution charts while the development of new photographic materials points to the need in

the near future for similarly new types of

density standards. What may occur in the

optical industry is conjectural. Domestic

sales of passive optics (lenses, lens instruments, binoculars, etc.) have been relatively stable for a few years, rapid growth being

seen in the electro-optical industry in

which lens devices are coupled to electronic

sensors. The evolution of the measurement

system in lens testing and evaluation will

likely be accelerated by the awaited documentary standards.

42
Appendix A. THE METHODOLGY OF THE STUDY

The starting point for the preparation

of this report was NBS records of its

calibration services. Computer lists of the

companies, organizations, and individuals

which had purchased NBS standards were compiled and, where practical, the entries

grouped according to the products or ser- vices they supply as described in the Thomas

Register of Manufacturers.

Letters soliciting information were sent

to 50 optical companies, 30 instrument manufacturers, and 25 trade and professional or- ganizations. Those not represented in NBS

records were located in directories such as The Optical Industry and Systems Directory.

The letters stated the nature of the study,

its purpose, the use to which information

would be put, and a statement of deference

to the requirements of proprietary operations . A survey questionnaire was prepared with

the advice of the Bureau of the Census and

sent to over 150 domestic industrial establishments which procured NBS photographic

density standards in the period for which

records were examined, specifically, June

1971 to December 1972. Survey questions were

directed at the nature of the products or services related to the standards, the rea- son for acquiring NBS standards, the number

and kind of measuring instruments used, the

personnel and time devoted to measurement,

the product volume effected, and the adequacy of the services NBS provides. A sample

questionnaire and a compilation of the

quantitative results follow this text. For information on the role of regulatory agencies, personal visits were made to the Federal Aviation Agency, the Department

of Transportation, the Hazardous Materials

Regulation Board, and the National Transportation Safety Board; telephone conversations

were held with appropriate level personnel

of the former Atomic Energy Commission, now

the Nuclear Regulatory Commission, the

Bureau of Radiological Health, and the

National Institute of Occupational Health and

Safety. Information on the system of eye care was derived from confirming the salient

facts reported in the popular press article

mentioned in the body of the report with the

standards committee chairman and medical

personnel referred to in that article.

Data compiled on documentary standards

derived from interviews with the chairmen of

the American National Standards Institute

committees on photographic sensitometry , the

subcommittee on medical densitometry, the

technical director of the National Microfilm

Association, a representative to the International Standards Organization, the director of the Gravure Technical Association,

and NBS representatives to the subcommittees

on lens testing and microdensitometry. Copies of the documents were procured from the

NBS library of standards and specifications.

Economic data per se were obtained from a number of sources, two being market research

fimrs which graciously provided reports on

the photographic industry: Predicasts, Inc.,

of Cleveland, Ohio and the Arthur D. Little

firm of New York. The Department of Commerce Office of Business Analysis submitted the

documents cited in the text. General overviews of the operations of

the measurement system were provided by: the

manager of a radiographic training center

(industrial radiography); the chairman of a American National Standards committee (medical radiology); the author of a comprehensive text-book chapter on ophthalmic measurements (eye care); a pipeline specialist of

the Hazardous Materials Regulation Board (radiography and pipelines); an FAA official

and an investigator for the National Transportation Safety Board (radiography and aerospace systems); a densitometer manufacturer

and a photographic goods producer (densitometery in general); an official of the Gra- vure Technical Association (densitometry and

printing); the technical director of the

National Microfilm Association (commercial

microfilming); and a number of workers in

the field of optical testing in general.

The requirements of the defense agencies in

advanced optical testing were documented in

letters from the officials of selected or- ganizations within those agencies.

Further bits and pieces of information

derived from numerous telephone conversattions, plant visits, standards committee

meetings, and discussions with workers in

the field. The more important source persons and documents are listed in Appendix B.

Appendix B. SUMMARY OF BACKGROUND DOCUMENTS

The information upon which this report is

based derived from a number of sources, many

of which were published books and documents,

some of which were written communications to the author. The following is a list of approximately 100 persons who graciously an- swered questionnaires, provided substantial

letters outlining their measurement programs,

submitted technical literature, documentary

standards, economic data or general background information. Their names, titles,

and affiliations are given, as well as the

nature of the contact which led to the data

transfer. Also included are the published

documents cited in the text and those which

were sources of more general data.

43
OMB No. 41 -S73042 APPROVAL EXPIRES 12-31-73 NBS-746

17-73) U. S. DEPARTMENT OF COiVllVIERCE NATIONAL BUREAU OF STANDARDS

EVALUATION OF PHOTOGRAPHIC STEP TABLETS

COMPANY IName and Address) RESPONDENT (Name)

ADDRESS (Business)

TITLE PHONE

ADMINISTRATIVE CONTACT IName) TECHNICAL CONTACT (Name)

ADDRESS (Business) ADDRESS (Business)

TITLE PHONE TITLE PHONE

1. TYPE OF CALIBRATION SERVICE EMPLOYED

1 1 PURCHASE OF STANDARD REFERENCE MATERIAL

1 1 PHOTOGRAPHIC STEP TABLET B1008

1 1 PHOTOGRAPHIC STEP TABLET #1009

[^STANDARD SUBMITTED FOR ORDINARY CALIBRATION

1

1 NEUTRAL DENSITY PHOTO TABLET

1 1 DOUBLE EMULSION X-RAY TABLET

QSPECIAL INVERSE SQUARE BAR CALIBRATION

1 1 NEUTRAL DENSITY PHOTO TABLET

1 1 DOUBLE EMULSION X-RAY TABLET

2. REASONS FOR CALIBRATION REQUIREMENTS

Q SELF-IMPOSED PRODUCTION STANDARD

[^CONSUMER'S PROCUREMENT REQUIREMENT

1 1 GOVERNMENT (GSA)

1

1 MILITARY SPEC. (DBA) Q OTHER ISpecifv) Q RESEARCH OR PRODUCT DEVELOPMENT TOOL

\^ OTHER (Specify)

1 CONTINUED NEXT PAGE

44
3. PRODUCTS

A. PLEASE ENUMERATE THE PRODUCTS OR SERVICES OF YOUR COMPANY WHICH ARE DEPENDENT UPON THE CALIBRATION SERVICE.

B. PLEASE ENUMERATE THE CONSUMERS BY NAME OR TYPEl WHOM YOU SERVE.

4. COMPANY STANDARDS CONTROL

A. PLEASE INDICATE THE USES OF THE STEP TABLETS.

'

\ DIRECT INSTRUMENT CALIBRATION

', COMPARISON STANDARD ~ CALIBRATION OF SECONDARY STANDARDS ~ FOR INTERNAL COMPANY USE

'. FOR DISTRIBUTION TO CUSTOMERS

!

I OTHER fSpecifvl

5. COMPANY MEASUREMENT SYSTEM

A. HOW MANY DENSITOMETERS ARE IN USE'

RESEARCH LABORATORY

METROLOGY LABORATORY

PRODUCTION CONTROL

OTHER ISpeeifYI

B. WHAT TYPES OF DENSITOMETERS ARE IN USE?

C. WHAT IS THE CAPITAL INVESTMENT IN THE MEASUREMENT SYSTEM?

D. HOW MANY PERSONNEL fAnd/or man-hours per week) ARE INVOLVED IN MEASUREMENT?

2 CONTINUED NEXT PAGE

45
6. CALIBRATION SERVICES SUPPLIED BY NBS

A. PRESENT ACCURACIES OF STEP TABLET CALIBRATIONS (Q MEET, QfALL SHORT OF, [^1 EXCEED)

PRESENT COMPANY REQUIREMENTS. COMMENT.

B. PRESENT ACCURACIES OF STEP TABLET CALIBRATIONS (QmeET, QfaLL SHORT OF. [^| EXCEED)

ANTICIPATED COMPANY REQUIREMENTS.

C. WOULD CHANGES IN THE SERVICES SUPPLIED BY NBS CONCERNING DENSITY STANDARDS (FORM,

ACCURACY, TYPE, SUPPORTIVE INFORMATION) AID YOUR COMPANY IN IMPROVING YOUR PRODUCTS,

INCREASING RELIABILITY, OR REDUCING COST' COMMENT.

D. HOW ARE PRESENT SERVICES RELATED TO PRODUCT DEVELOPMENT. PRODUCTION, RELIABILITY OR COST?

E. IS THERE A RELATION BETWEEN THE CALIBRATION SERVICES AND INFORMATION WE COULD

PROVIDE TO YOU AND CONSUMER HEALTH AND SAFETY' THE DEVELOPMENT OF NEW TECHNOLOGIES? YOUR COMPETITIVE POSITION IN WORLD MARKETS?

COULD THIS RELATION BE ALTERED OR IMPROVED BY ANY CHANGES ON THE PART OF NBS IN ITS PHOTOGRAPHIC DENSITY CALIBRATION SERVICE?

CONTINUED NEXT PAGE

46
7. MEASUREMENT PROCESS AND PRODUCT VALUE

A. WHAT DOLLAR-VOLUME OF PRODUCT IS EFFECTED BY THE CALIBRATION SERVICE^

B. WHAT IS THE DOLLAR VALUE-ADDED TO THE PRODUCT EFFECTED BY THE SERVICE'

8. REMARKS

4 USCOMM-NBS-OC

47
QUANTITATIVE RESULTS OF SURVEY OF NBS SRM 1008

AND 1009 STEP TABLET USERS

Population polled: One hundred and forty seven domestic industrial consumers of SRM

Materials 1008 and 1009 (photographic Transmission Density Step

Tablets) for the period April 1971 - January 1973.

Primary Field of Application : Total population polled, as inferred from industry index information of company products.

Industrial NDT 124 (86%)

Graphics and Printing 21 (14%)

Total 145 (100%)

Total respondents, as indicated by response.

Industrial NDT 31 (84%)

Graphics and Printing 6 (16%)

Total 37 (100%)

Respondents Specification of Reason For Calibration By NBS Standard

Federal requirement (MIL-STD, AEC, etc.) 31 Self-imposed production standard 6 Total 37

Type of Calibration

SRM 1008 and/or 1009 17 SRM 1008, 1009 plus double emulsion

Xray film (PW XRMl) 3 Double emulsion film only 13

SRM 1008, 1009 plus special neutral

density tablet 2 Neutral density tablet only 2 37

Number of Densitometers in Respondents Facility

Companies #Densitometers Subtotals

14 1 14

6 2 12

7 3 21

2 4 8

1 5 5

3 8 24

1 18 18

4 NR

37 102

(Average per company for 33 responses, 3)

48
Densitometer Investment and Supplies

Companies Investment Companies Brand

9 $1 K or less 18 MacBeth

10 $1-5 K 12 Photovolt

5 $5 K or greater 5 Kodak

11 NR 2 Sargent Welch

37 1 Joyce Loebl

1 GE

3 NR

Personnel Involved in Densitometric Measurement

Companies Persons Companies Manhours/Week

10 4 or less 10 5 or less

5 5-10 8 6-10

3 10-20 6 Greater than 10

19 NR 3 NR

37 37

49
Selected List of Individuals Responding to Contacts

Response Code P: personal interview

T: telephone contact

R: survey respondent

V: plant visit

L: simple letter

S: substantive letter

C: literature/cover letter

Code Alphabetical List by Individual

L Robert A. Abbott

Technical Director

American Society for Quality Control

761 West Wisconsin Avenue

Milwaukee, Wisconsin 53203

414-272-8575

L Dr. Eugene Allen

National Printing Ink Research In- stitute

F. M. Sinclair Memorial Library

Lehigh University

Bethlehem, Pennsylvania 18015

215-691-7000 Ext. 220 or 560

R S. Arimura

General Dynamics

Convair Aerospace Division

P. 0. Box 80847

San Diego, California 92138

P Don M. Avedon

Technical Director

National Microfilm Association

Suite 1101, 8728 Colesville Road

Silver Spring, Maryland

301-587-8444

D Richard Becherer

Research Division

Polariod Corporation

28 Osborn Street

Cambridge, Massachusetts 02139

617-864-6000 Ext. 4447

R R. C. Bevan

General Manager

CBL Industries, Inc. 13810 Enterprise Avenue

Cleveland, Ohio 44135

216- 267-4142

Code Alphabetical List by Individual

T Richard M. Blassey

Office of Business Research and

Analysis

Photographic Products

Department of Commerce - Main

Washington, D. C. 20230

202-967-2702

L I. Bob Blumenthal

130 Country Court Road

Garden City Park, New York 11040

516-741-0430

R J. J. Bockheim

Laboratory Director

Jervis Corporation

2900 N. Wilson Street

Grandville, Michigan 49418

616- 534-8621

R Sherman H. Boyd

Staff Scientist

Stromberg Datagraphic Inc.

P. 0. Box 2449

San Diego, California 92112

714-291-9960

C Frederick Brech

Fisher Scientific

Jarell Ash Division

590 Lincoln Street

Waltham, Massachusetts 02159

617-890-4300

P,V Raymond Brown

Lighting Specialist

General Electric Company

Large Lamp Division, Nela Park

East Cleveland, Ohio 44112

216-266-2121 Ext. 2366

50
Code Alphabetical List by Individual

L Lysl D. Cahill

President

Mead Technology Laboratories

Suite 206

1611 North Kent Street

Arlington, Virginia 22209

703-525-2674

Code Alphabetical List by Individual

R W. Carey Dowd III President

The Dowd Press , Inc. 114 W. Bland Street

P. 0. Box 3277

Charlotte, North Carolina 28203

704-332-5017

Dr. Erie T. Clarke

Chairman, ANSI Subcommittee on Medical Densitometry

Technical Operations, Inc. Radiation Products Division

South Avenue

Burlington, Massachusetts 01803

617-272-2000

John L. Clark, Jr. Senior Marketing Specialist

Optical Products Division

Corning Glass Works

Corning, New York 14830

607-962-4444

Edward Criscuolo

Physical Scientist

Nondestructive Test Group

Naval Ordnance Laboratory

Silver Spring, Maryland 20910

301-394-1973

Warren L. Daum

VP-Executive Director

Gravure Technical Associates

60 East 42nd Street

New York, New York 10017

212-661-8936

Howard Diamond

President

Transidyne General Corporation

462 South Wagner Road Ann Arbor, Michigan 48106

313-769-1900

James T. Dougherty

Assistant Chief, Maintenance Division

Flight Standards Service

FAA, DOT

800 Independence Avenue

Washington, D. C. 20553

202-426-8213

Terry D. Douglas

Manager

Life Science Products

Ortec Inc. 100 Midland Road

Oak Ridge, Tennessee 37830

615-482-4411

R Stanley R. Drake

Mechanical Engineer

Bendix Corporation

P. 0. Box 1159

Kansas City, Missouri 64141

816-363-3211

P,V Frank Drei singer

Medical X-Ray Sales

Picker X-Ray Corporation

595 Miner Road

Cleveland, Ohio

216-449-3000

R George W, Eckert

Superintendent, NDT Department

Crane Company - Midwest Fittings

1450 South 2nd Street

St. Louis, Missouri 63166

314-621-8300

R,T Robert A. Eglund

Manager, Quality Control

Hitchcock Industries

8701 Harriet Avenue South

Minneapolis, Minnesota 55420

512-888-9271

R Ronald E. Fabry

Manager, Quality Control

Peerless Aluminum Foundry Company, Inc.

55 Andover Street

Bridgeport, Connecticut 06605

203-366-4761

V Harold P. Field

President

Gamma Scientific Corporation

3777 Ruffin Road

San Diego, California 92123

714-279-8034

P James French

Standards Executive

Scientific Apparatus Makers Association

1140 Connecticut Avenue, N. W. Washington, D. C. 20036

202-223-1360

R William T. Fritts

Senior NDT Engineer

Monsanto Research Corporation

Mound Laboratory

51
Code Alphabetical List by Individual Code Alphabetical List by Individual

Miamisburg, Ohio 45342

513-866-7444

R C. J. Gluch

Manager, Quality Control

Magnaflux Corporation

Magnaflux Testing Labs

7300 W. Lawrence Avenue

Chicago, Illinois 60656

312-867-8000

T Dr. Martin Goldspiel

Chief, Hospital X-Ray Equipment

Defense Personnel Support Center

Philadelphia, Pennsylvania 19100

215-271-2125

T Dr. Samuel Goldspiel

Inspection Division

Board of Water Supply

1250 Broadway Avenue

New York, New York 10001 , 212- 566-4737

R Michael Grauman

Manager, Quality Control

X-Ray Products Corporation

7829 Industry Avenue

Pico Rivera, California 90660

213- 723-0741

P Franc Grum

Corporate Contact

Research Laboratories

Kodak Park Division

Eastman Kodak

901 Elmgrove Road

Rochester, New York 14650

716-458-1000 Ex. 77827 ,

S James C. Haley, Chief

Dynamics and Environment Evaluation

Branch

Department of the Air Force

Air Force Avionics Laboratory

Wright Patterson Air Force Base,

Ohio 45433

R E. G. Harris

President

Cedtech Testing Laboratories

10708 South Garfield Avenue

South Gate, California 90280

213-773-7835

S A. F. Harrison

Executive Director

National Board of Boiler and Pressure

Vessel Inspectors

1155 N. High Street

Columbus, Ohio 43201

614-294-4957

52

P Caleb Hathaway

Scientific Instruments

Office of Business Research and

Analysis

Room 1126

Department of Commerce - Main

Washington, D.C. 20230

202-967-2934

L Howard Haynes

Office of Technical Director

Illuminating Engineering Society

United Engineering Center

345 East 47th Street

New York, New York 10017

212-PL2-6800

P,V Ralph D. Helwig

Senior Research Associate

Predicasts, Inc. 200 University Circle Research Center

11001 Cedar Avenue

Cleveland, Ohio 44106

216-795-3000

P,V Dr. Richard C. Honey

Program Manager

Optics Information Science and

Engineering Center

Stanford Research Institute

333 Ravenswood Avenue

Menlo Park, California 94025

415-326-6200

S Robert E. Hopkins

Tropel , Inc.

P. 0. Box 164

52 West Avenue

Fairport, New York 14450

716-377-3200

L Wright H. Huntley, Jr. President

Holograf, Inc. 670 National Avenue

Mountain View, California 94043

415-967-2323

P,V Richard Keough

Vice President

Micro COM, Inc. Computer Management

3121 Euclid Avenue

Cleveland, Ohio 44115

216-881-9180

R E. Kob

Photographic Engineer

Scott Graphics, Inc. Holoyoke, Massachusetts 01040

413-536-7800 Ext. 647
Code Alphabetical List by Individual

R Irving L. Kofsky

President

Photometries, Inc. 442 Marrett Road

Lexington, Massachusetts 02173

617-862-8050

T F. E. Kruesi

Director of Operations

Compliance Group

Atomic Energy Commission

Germantown, Maryland 20767

301-973-7397

L Teddi C. Laurin

Editor, Optical Spectra

Optical Publishing Company

Pittsfield, Massachusetts, 01201

413-499-0514

R John H. Leins, Sr. Laboratory Manager

Metals Testing Company, Inc.

1 Bi dwell Road & John Fitch

Boulevard

South Windsor, Connecticut 06074

203-289-8225

R John Levonick

Foreman

Howmet Corporation

Austenal Division

Roy Street

Dover, New Jersey 07801

201- 361-0300 Ext. 255

T,S A. S. Longo

Supervisor, MCL X-Ray

Pratt and Whitney Aircraft

400 Main Street

East Hartford, Connecticut 06108

203-565-7799

P Herman Lowenkar

Market Analyst

DMS, Inc. 100 Northfield Street

Greenwick, Connecticut 06830

203-661-7800

P,V Michael Marx

Metal lurgist

Bureau of Aviation Safety

National Transportation Safety Board

800 Independence Avenue

Washington, D.C. 20553

202- 426-3820

R Robert P. Mason

Senior Research Scientist

Logetronics Inc. 7001 Loisdale Road

Code Alphabetical List by Individual

Springfield, Virginia 22150

703-971-1400 Ext. 317

L James R. Massa

Production Methods Engineer

World Color, Inc.

P. 0. Box 1327

Ormond Beach, California 32074

904-677-1332

P C. S. McCamy

Vice President

MacBeth Color and Photometry Division

Kollmorgen Corporation

P. 0. Box 950

Newburgh, New York 12550

914-561-7300

T R. W. McClung

Chairman. E07 Committee

American Society of Nondestructive

Testing

Union Carbide

Oak Ridge National Laboratory

P. 0. Box X Oak Ridge, Tennessee 37830

P,V William McNair

Nondestructive Testing Specialist

FAA, DOT

800 Independence Avenue

Washington, D. C. 20553

202-426-8151

L James W. Meehan

Sales Manager

Ealing Optics Division

2225 Massachusetts Avenue

Cambridge, Massachusetts 02140

617-491-5870

R Gordon H. Moline

General Manager

Industrial Heat Treating and

Metallurgical Co., Inc. 2131 Northwestern Avenue

Indianapolis, Indiana 46202

317-924-4321

R Carl M. Modes

President

Universal Tech. Testing Labs, Inc.

P. 0. Box 372

Collingdale, Pennsylvania 19023

215- 586-3070

R Robert H. Nehus

Engineer

TRW Metals Division

P. 0. Box 250

Minerva, Ohio 44657

216- 868-7280

53
Code Alphabetical List by Individual

R C. Douglas O'Dell

Superintendent

Logetronics Inc. 112 Starlite Street

South San Francisco, California 94080

415-588-5404

R Albert Papai

Engineer, Quality Control

Howmet Corporation

Austenal Division

1110 E. Lincolnway

La Porte, Indiana 46350

219-362-6161

S Hayden B. Peake

Project Officer

Office of Space Systems

Office of Secretary

Department of the Air Force

Washington, D. C. 20330

R J. D. Pike

Engineer, Quality Control

Howmet Corporation

Mi SCO Drive

Whitehall, Michigan 49461

616-894-4066

R Charles A. Potter, Jr. President

Microfilm Services, Inc.

P. 0. Box 212

Martinsville, New Jersey 08836

201-469-0010

P,V Kendall Preston

Senior Staff Scientist

Electro-Optical Division

Perkin Elmer Corporation

Wooster Heights Road

Danbury, Connecticut 06810

203-744-4000

P David Puthof

Engineer

Division of Laboratories and

Criterial Development

NIOSH

944 Chestnut Road

Morgantown, West Virginia 26505

304-599-7335

S George 0. Reynolds

Director

Applied Sciences Department

Technical Operations, Inc. Northwest Industrial Park

Burlington, Massachusetts 01803

617- 272-2000

Code Alphabetical List by Individual

S K. E. Reynolds

Executive Vice President

Wild Heerbrugg Instruments Inc. 465 Smith Street

Farmingdale, New York 11735

516-293-7400

R Donald G. Robbins

Purchasing Agent

Hoosier Metal Fabricators, Inc. 1001 Evans Road

Gas City, Indiana 46933

317-674-2266 Ext. 32

R Dave Ross

X-Ray Supervisor

Wellman Dynamics Corporation

U. S. Route 34

Creston. Iowa 50801

515- 782-8521 Ext. 259

P,V Mark Rosumny

Manager, Radiographic Training Center

Diano Corporation

1020 London Road

Cleveland, Ohio 44110

216-449-3000

T,R J. Milton Schneider

Plant Manager

Consolidated Testing Laboratories,

Inc. 79 Herri cks Road

New Hyde Park, New York 11040

516- PI6-3705

R James G. Schneeman

President

X-Ray Products Corporation

Pico Rivera, California 90660

213-723-0741

P,V Messrs. Schade, Caspers and Marl in

Electronics Materials Science

Division

Naval Electronics Laboratory Center

San Diego, California 92112

714-225-6591

S Wallace Seward

Assistant Senior Vice President

Industry Affairs

American Petroleum Institute

1801 K Street N.W. Washington, D. C. 20006

202-833-5660

54
Code Alphabetical List by Individual

P.V H. M. Shepherd

Pipeline Safety Specialist

National Transportation Safety

Board

Washington, D. C. 20591

202-426-3820

R James J. Shiplett

President

Quality Assurance Laboratories, Inc. 80 Pleasant Avenue

South Portland, Maine 04106

207-799-8911

S John M. Simpson, Jr. Manager, Optics Technology

Bausch and Lomb

635 St. Paul Street

Rochester, New York 14602

716-232-6000

S R. Dow Smith

Itek Corporation

10 MacQuire Road

2448 Sixth Street

Berkeley, California 94710

415-843-6836

R Robert Smith

Head, Quality Control

Tinsley Laboratories, Inc. 2448 Sixth Street

Berkeley, California 94710

415-843-6836

S Miles Southworth

Professor, School of Printing

Rochester Institute of Technology

One Lomb Memorial Drive

Rochester, New York 14623

716-464-2766

P.V William Sunter

Visual Systems Section

NASA - Ames Research Center

Moffett Field

Mountain View, California 94035

415-961-1111

S George A. Taylor

Reconnaissance Sensor Development

Branch

Department of the Air Force

Air Force Avionics Laboratory

Wright Patterson Air Force Base,

Ohio 45433

Herbert Thieret

Herron Testing Laboratories

5405 Shaff Road

Cleveland, Ohio 44138

216-524-1450

Code Alphabetical List by Individual

P,T Brian Thompson

Professor, Institute of Optics

Rochester Institute of Technology

One Lomb Memorial Drive

Rochester, New York 14623

716- 464-2766

T John Thompson

Public Relations

Arthur D. Little, Inc. Acorn Park

Cambridge, Massachusetts 02140

617-864-5770

R G. W. Turk

Vice President

Radiation Equipment Company, Inc. Inspection Systems Division

1495 Old Deerfield Road

Highland Park, Illinois 60036

312-831-2900

L. W. Utley

Mechanical Research and Development

Dow Chemical Company

Rocky Flats Division

P. 0. Box 888

Golden, Colorado 80401

303-494-3311

R Harry F. Wahl

Supervisor NOT

Dansville Metal Stamping Company,

Inc.

17 Oakwood Avenue

Danville, Illinois 61832

217-446-0647

T Kenneth Weaver

Chief, Medical Physics Section

Division of Electronic Products

Bureau of Radiological Health

FDA Rockville, Maryland 20852

301-443-2536

R D. R. Wells

Supervisor NDE Foster Wheeler Corporation

Mountaintop, Pennsylvania 18707

717- 474-6366

C Jon T. West

Product Manager, Electrophoresis

Canalco, Inc. 5635 Fisher Lane

Rockville, Maryland 20852

301-881-8090

R P. D. Whitten

Manager, Nondestructive Testing

Babcock & Wilcox Company

55
Code Alphabetical List by Individual

P. 0. Box 785

Lynchburg, Virginia 24505

703-384-5111

R John F. Wodicka

Manager, Quality Assurance

Arwood Corporation

839 Poquonnock Road

Groton, Connecticut 06340

203-445-7421

R G. J. Woods

Supervisor, Quality Assurance

Rohr Industries, Inc.

P. 0. Box 878

Chula Vista, California 92012

714-426-7111 Ext. 2377

R David Worden

Purchasing Agent

The Stalker Corporation

903 Woodside Avenue

Essexville, Michigan 48732

517-893-7562

L Graham B. Wright

Manager

Spectrochemical Instruments Sales

Baird Atomics , Inc. 125 Middlesex Turnpike

Bedford, Massachusetts 01730

617-276-6000

R Mr. A. F. Venegas

Treasurer

Venegas Industrial Testing Labs, Inc.

9 Pel ham Street

Nashua, New Hampshire 03060

603-883-0796

DOCUMENTARY SOURCES OR INFORMATION

USED IN TEXT

Private Studies of Photographic

Market

P31; "Photographic Equipment and

Supplies", Predicasts, Inc., Cleveland, September, 1972.

"The U. S. Photographic Industry 1970-

1975", E. D. Novak and I. D. Robinson,

Arthur D. Little, Inc., October, 1971.

Supplemental Private Sources of

Economic Data

"The Analytical Instrument Market", Frost

and Sullivan, Inc., New York, August,

1972.

"The Government Laser Market", Frost

and Sullivan, Inc., Now York, April,

1973.

"The Optoelectrics Market", Frost

and Sullivan, Inc., New York, March,

1973.

"Petroleum Facts and Figures", 1971

Edition, Am. Petroleum Institute

Washington, D. C, May, 1971.

"Annual Statistical Review", U. S. Petroleum Industry Statistics, 1956-

1972; Division of Statistics and

Economics, Am. Petroleum Institute,

Washington, D.C. , 1973.

Department of Commerce Economic Data

"U.S. Industrial Outlook 1973", D.O.C.,

Domestic and International Business

Administration, BCABP-452-08-73-001,

1973.

"Selected Instruments and Related

Products", Current Industrial Reports,

MA-38B-(71)-1, D.O.C., Bureau of the

Census, March, 1973.

"Industry Looks to Continued Growth",

Optical Industry News, Vol. 1, JulyAugust, 1973.

Documentary Standards

"An Index of U.S. Voluntary Engineering

Standards", NBS Special Publication

329, D.O.C., W. J. Slattery, Editor,

March, 1971,

"Pressing Problems and Projected

National Needs in Optical Radiation

Measurements", U.S. National Committee,

E.I.E., 1972.

"1973 Catalog", American National

Standards Institute, March, 1973.

"Directary of Committee Memberships

of the NBS Staff of Engineering

Standards Committe", Office of

Engineering and Information Pro- cessing Standards, NBS, D.O.C.,

September, 1973.

Industry Radiography

"Radiograph in Modern Industry", 2nd

Edition, 1957, Eastman Kodak Co.,

X-ray Division, Rochester.

"The Fundamentals of Radiography",

56
Radiography Markets Division,

Eastman Kodak Co. , 1968.

"Radiography Inspection", J. L. Ballard; presented annual ASMA,

Petroleum Section Conference, Dallas,

Texas, Sept., 1968.

"Nondestructive Testing", B. G. Barker,

Report No. 399, Stanford Research

Institute, February, 1970.

"The Greening of Nondestructive

Testing", R. E. Turner, Quality

Management and Engineering, May, 1972.

"Fundamental of Industrial X-ray and

Safety", Manual 6013072, Picker Corporation, Industrial and Scientific

Apparatus Div. Cleveland, June, 1971.

Aviation Industry

"Forecast and Inventory", Aviation

Week and Space Technology 98; March

19, 1973.

"FAA Looks Again at NOT", James E. Dougherty, Flight Standards Service,

FAA, Houston, September 11-13, 1973.

Maintenance Review Board Report,

Boeing 747 Maintenance Program; DOT,

FAA, January, 1971.

Aircraft Accident Report, NTSB-AAR73-18; Air Iowa, Inc., April, 1973.

Aircraft Accident Report, NTSB-AAR70-16; Wien Consolidated Airlines,

Inc., December 2, 1968.

"The Washington Merry-Go-Round" , J. Anderson, The Washington Post, May

12, 1973.

Miorographios

"Introduction to Micrographics",

National Microfilm Assoc., Silver

Spring, Md. ; 1973.

"Micrographics", Global Market Survey,

DOC, Domestic and International

Business Administration, April, 1973.

Buyer's Guide to Microfilm Equipment,

Products and Services, National Microfilm Association, Silver Spring, Md.;

1973.

Medical Radiology

"Proposal for Program on Automated

Analysis of Medical X-rays", Perkin

Elmer Optical Technology Division,

for the National Science Foundation;

October, 1973.

"Hazards in the use of X-ray Analytical Instrumentation", R. Jenkins and

D. J. Haus, X-ray Spectrometry 2,

1973.

Draft: "Report on the Need for

Federal Standards for X-ray Image

Receptor Systems", S. J. Harris, Reg.

II, BRH/FDA, Brooklyn, N. Y.,

Jan., 1972.

Personal Communication, To Radiation

Safety Coordinator, I.B.S., DOC,

NBS from Director, Department of

Health, Office of Radiation Control,

City of N. Y.; Oct. 4, 1973.

Summary Report of the Sub- Committee

on Need for Photoreceptor Information",

S. Vickers, et al , committee report to American College of Radiology, Commission on Radiologic Units, Standards

and Protections; November, 1972.

Selected Section Publications

"Measurement of the Second - Order

Degree of Coherence by Means of a Wavefront Shearing Interferometer",

D. N. Grimes, App. Optics 10, 1567

(1971). ~

"Imaging of Tri-bar Targets and the

Theortical Resolution limit in Par- tically Coherence Illumination", D.

N. Grimes, J. Op. Soc. Am. 61. 1263

(1971). —

"Conditions for Microdensitometer

Linearity", R. E. Swing, J. Opt.

Soc. Am. 62, 199 (1972).

"Optical Autocorrelator with Special

Application to MFT Measurement", D.

N. Grimes, App. Optics 11_, 914 (1972).

"Interferometric Lens Testing", D. Grimes and J. Jerke, NBS Report

10827, March, 1972.

"Interim Technical Report on the

Problems of Linear Microdensitometry", R. E. Swing, NBS Report

10879, June, 1972.

57
"The Linear Microdensitometer Study",

D. Nyyssonen, NBS Report 10948,

November, 1972.

"The Extension of the Real-Time

Testing System to Microscope

Systems", D. Nyyssonen, NBS

Report 10947, November, 1972.

"Basic Considerations of

Densitometer Adjustment and Calibration"

R. E. Swing, NBS Report 10970, Dec. 20,

1972.

"Feasibility Study for Truck Optical

Surveillance", NBS Report 10967, DOC,

December, 1972.
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET NBSIR 75-9A2

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

The National Measurement System for Optics

5. Publication Date

6* Performing Organization Code

7. AUTHOR(S) Dennis A. Swyt

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No.

11. Contract/Grant No.

12. sponsoring Organization Name and Complete Address (Street, City, State, ZIP) 13. Type of Report & Period Covered

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summery of most si^ificant information. If document includes a significant

bibliography or literature survey, mention it here.)

NBS has conducted a study of the National Measurement System for Optics.

The proposed system model is discussed including the role of standards committees,

instrument manufacturers and measurement users. The economic dimensions of the

measurements impact areas and the technological base from which new measurement

technology springs are described.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Imaging optics; National Measurement System; photographic density; microcopy

resolution charts; lens testing; technology assessment.

18. AVAILABILITY \Z2 Unlimited

n? For Official Distribution. Do Not Release to NTIS

I

' Order From Sup. of Doc, U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. CH

I I Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

22. Price

USCOMM.DC 29042-P74