Computer

Systems

Technology

U.S. DEPARTMENT OF

COMMERCE

National Institute of Standards and

Technology

Nisr

NAT L INST. OF STAND S TECH R I.C

NIST Special Publication 500-191

Test Methods for Optical Disk

l\/ledia Characteristics

(for 356 mm Ruggedized Magneto-optic Media)

Fernando L Podio

A111D3

I

H\S1

I PUBUCATiONS

—QC

100

.U57

500-191

1991

C.2

NIST Special Publication 500-191

Test Methods for Optical Disk

Media Characteristics

(for 356 mm Ruggedized Magneto-optic Media)

Fernando L. Podio, Editor

Advanced Systems Division

Computer Systems Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899

Sponsored by:

National Aeronautics and

Space Administration

Langley Researcii Center

Hampton, VA 23665-5225

September 1991

U.S. DEPARTMENT OF COMMERCE

Robert A. Mosbacher, Secretary

NATIONAL INSTITUTE OF STANDARDS

AND TECHNOLOGY

John W. Lyons, Director
Reports on Computer Systems Technology

The National Institute of Standards and Technology (NIST) has a unique responsibility for computer

systems technology within the Federal government. NIST's Computer Systems Laboratory (CSL) develops standards and guidelines, provides technical assistance, and conducts research for computers and

related telecommunications systems to achieve more effective utilization of Federal information technology resources. CSL's responsibilities include development of technical, management, physical, and administrative standards and guidelines for the cost-effective security and privacy of sensitive unclassified

information processed in Federal computers. CSL assists agencies in developing security plans and in improving computer security awareness training. This Special Publication 500 series reports CSL re- search and guidelines to Federal agencies as well as to organizations in industry, government, and

academia.

National Institute of Standards and Technology Special Publication 500-191

Natl. Inst. Stand. Technol. Spec. Publ. 500-191, 74 pages (Sept. 1991)

CODEN: NSPUE2

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1991

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402
Foreword

The National Aeronautics and Space Administration (NASA) is responsible for the

Spaceflight Optical Disk Recorder (SODR) program, which is managed by the Langley

Research Center. The SODR program includes the concept of developing disk drive

storage modules containing high capacity ruggedized erasable optical disks, and the

development of a modular controller. This forms the basis for an expandable system

that can be configured for specific applications.

The optical disk recorder is intended for use aboard unmanned polar orbiting Earth

Observing System (EOS) platforms and Space Station spacecraft. The goal is to have

a high performance, high capacity ruggedized erasable optical disk system capable of

providing the complex onboard data storage and buffer functions needed for the EOS

and Space Station spacecraft. In addition to the space-based applications, there are

similar ground-based applications, such as supercomputer mass storage and spaceflight

experiment data downlink buffers, that could benefit substantially from advances in storage technology leading to erasable, high-rate, high-capacity systems.

The need for physical interchange standards and standard test methods for measuring

media characteristics for the type of media that would be used in these systems is apparent. These standards will allow competing firms to develop products, making it possible for NASA to select a product for which there are multiple vendors. Standard

test methods will also allow conformance verification of such standards. At the present

time, National and International industry voluntary standards committees are not working

in the development of media interchange standards and standard test methods for high

performance and high capacity ruggedized erasable media.

Because of the lack of these media interchange standards and standard test methods,

in 1989 NASA sponsored a program of work at the National Institute of Standards and

Technology (NIST) to develop media specifications and test methods for measuring

media characteristics for ruggedized erasable optical disks, by consensus building

between NIST, NASA, and interested parties in industry. These media specifications and

test methods would be included in two separate documents that would be used as

reference documents or as guidelines for U.S. Government agencies and industry

interested in specifying and testing this type of media technology.

iii
The Computer Systems Laboratory (CSL), an operational unit of the National Institute

of Standards and Technology (NIST), maintains membership in national and international

standards committees such as Technical Committee (TC) X3B11 and ISO/IEC

JTC1/SC23 in the development of media interchange standards and test methods

standards for optical digital data disks. CSL has project leadership for the development

of standard test methods for media characteristics in TC X3B11 and maintains

membership in the IT9/AES Joint Technical Commission (JTC) on Data Permanence.

The work of the JTC will eventually lead to the standardization of methods to predict

the life expectancy of optical computer storage media/systems. A member of CSL is also a technical liaison between TC X3B1 1 and the JTC.

Through its optical media research program, CSL has also been doing research on

optical media characteristics for several years. This program which began at CSL in 1985 includes stability studies of optical media, development of a testing laboratory for

optical media, and studies of the utilization of this technology. In support of its mission,

CSL works with U.S. Government agencies to assist in the development of policies,

standards, and methods for efficient management of information resources. CSL

currently has a cooperative program with the U.S. National Archives and Records

Administration through which CSL developed a testing methodology for deriving life expectancy values for optical media. CSL is now working on a study of care and

handling of optical media. CSL is also investigating the status of on-line monitoring

techniques for error rates and error distributions on optical disk subsystems.

To help NASA and industry develop media specifications and test methods, CSL

organized and chairs a NIST/NASA Working Group whose membership consists of

interested drive and media manufacturers, other interested federal government agencies,

NIST and NASA. The scope of this Working Group is to develop a set of test methods

for measuring media characteristics and a set of specifications for 356 mm ruggedized

erasable media/drives. During the first year of activity, the Working Group developed

a set of test methods for the media characteristics. The test methods were developed

for a 356 mm two-sided laminated glass substrate with a magneto-optic active layer

media technology. This publication documents these test methods.

It is my personal expectation that this document will be used as a guideline on how

to test this type of media technology. This document should also be a useful

contribution to other groups or standards committees in charge of documenting test

methods for optical media. The test methods included in this publication may be

appropriate for other media types, but their applicability must be evaluated on a case

by case basis.

iv
Because of the nature of the work, references were made to specific companies and

commercial products. The inclusion or omission of companies or products in this

publication does not imply an endorsement or a criticism by the National Institute of

Standards and Technology.

Fernando L Podio, Chair

and Technical Editor.

NIST/NASA Working Group for the development

of Test Methods and Specifications for

356 mm Ruggedized Rewritable Media.

V

Acknowledgments

I want to acknowledge all of those who made this work a success, including the

Working Group members who are listed in Appendix E. Special thanks are due to: Dr. Thomas A. Shull and John Stadler from NASA, Doug Stinson and Scott Gerger from

Kodak, Joe Cinelli and Taras Kozak from GE and Jathan Edwards from 3M. I am also

grateful to my NIST colleagues who contributed to the Working Group by providing

technical advice and reviewing documents. Some of the tests were derived from

material extracted from TO X3B1 1 draft standards and other TC X3B1 1 documents (see

Chapter 4, References). I am grateful to those TC X3B11 members who, through their

contributions to the work of TC X3B11, indirectly contributed to this Working Group.

vii

Contents

Foreword iii

Acknowledgments vii

Abstract xv

1 General 1

1.1 Scope 1 1.2 Purpose 1 1.3 References 1 1.4 Definitions 2

2 Testing Conditions 3

2.1 General Environment 3

2.2 Measurement Precision 4

2.3 Mechanical 4

2.4 Recording 6

2.4.1 General 6

2.4.2 Read Conditions 8

2.4.3 Write Conditions 8

2.4.4 Erase Conditions 8

3 Test Methods 9

3.1 Operational Environment Test 9

3.1.1 Thermal 10

3.2 Non-operational Environment Test 11

ix
3.2.1 Thermal 11

3.2.2 Humidity 12

3.2.3 Temperature-Altitude 12

3.2.4 Vibration 13

3.3 Storage Environment Test 14

3.3.1 Thermal 14

3.3.2 Humidity 14

3.3.3 Temperature-Altitude 14

3.4 Environmental Qualification 14

3.4.1 Radiation 15

3.4.2 Thermal Vacuum Stability Test (Outgassing) 16

3.4.3 Vibration 16

3.4.4 Thermal Cycling 17

3.4.5 Temperature-Altitude 17

3.5 Mechanical and Physical Characteristics 18

3.5.1 Dimensions of the Disk 18

3.5.2 Moment of Inertia 18

3.5.3 Imbalance 19

3.5.4 Dynamic Axial Runout 19

3.5.5 Axial Acceleration 21

3.5.6 Residual Focus Error 22

3.5.7 Dynamic Radial Runout 24

3.5.8 Radial Acceleration 26

3.5.9 Residual Tracking Error 27

3.5.10 Droop 29

3.5.11 Tilt 29

3.6 Substrate Characteristics 30

3.6.1 Index of Refraction 30

3.6.2 Double-pass Retardation 30

3.6.3 Thickness 31

3.7 Recording Layer Characteristics 31

X
3.7.1 Reflectance, Uniformity of Reflectance, and

Rate of Change of Reflectance 31

3.7.2 Resolution 32

3.7.3 Imbalance of the Magneto-optic Signal 33

3.7.4 Disk Retardation 33

3.7.5 Figure of Merit 35

3.7.6 Narrow Band Signal-to-noise Ratio 36

3.7.7 Crosstalk 37

3.7.8 Ease of Erasure 38

3.7.9 Optimum Write Power 39

3.7.10 Mark Uniformity 41

3.7.11 Raw Error Rate 42

3.8 Preformat Characteristics 43

3.8.1 Push-pull Signal 44

3.8.2 Track Crossing Signal 44

3.8.3 Preformat Data Signal 45

3.8.4 Track Pitch 45

3.9 Media Lifetime 45

3.9.1 Archival Life 46

3.9.2 Shelf Life 49

3.9.3 Read/Write/Erase Cycles 50

3.9.4 Extended Read 50

4 References 53

A The Optical System Seen by any Beam for Measuring Write, Read

and Erase Characteristics 55

B Definition of Write Pulse 57

0 1500 Hz Filter Implementation 59

D Determination of the Number of Transitions Required for

the Raw Error Rate Test 61

E Working Group Participants 63

xi
List of Figures

2.3.a Disk plan view 4

2.3.b Disk clamping method 5

3.1.1 Thermal cycle . 10

3.5.2 IVIoment of inertia test setup 18

3.5.4 Dynamic axial runout block diagram 20

3.5.6 Residual focus error test system 23

3.5.7 Dynamic radial runout block diagram 26

3.5.9 Residual tracking error test system 28

3.5.11 Tilt test setup 30

3.6.2 Double-pass retardation test setup 31

3.7.3 Imbalance of the magneto-optic signal 33

3.7.4 Disk retardation test instrument 34

3.7.6 Amplitude versus frequency 37

3.7.9 Mark length error versus write power 40

3.7.11 Raw error rate test setup 43

3.8 Preformat characteristics 44

3.9.1. a Incubation effect on the raw error rate 47

3.9. 1.b Extrapolated t^Q^ value for the archival and shelf life tests 48

A. I The optical system seen by any beam for measuring

write, read, and erase characteristics for Type A.I detection 56

B. I Definition of write pulse 57

C. I 1500 Hz filter implementation 59

xii
List of Tables

2.1 General environment 3

2.4.1 Testing conditions 7

3.1 Parameters for tine operational, non-operational, and

storage environment tests 9

3.4.1 Parameters for tine radiation test 15

3.4.4 Parameters for tine thermal cycling test 17

3.9.3 Parameters for the read/write/erase cycles test 51

xiii

Test Methods for Optical Disk

Media Characteristics

(for 356 mm Ruggedized Magneto-optic Media)

Fernando L. Podio

Technical Editor

Abstract

Standard test methods for computer storage media characteristics are essential and

allow for conformance verification to media interchange standards. Tests methods are

also needed to develop procedures which would allow for repeatability of results

among different industry and U.S. Government sites. The test procedures documented

in this publication reflect the work done by the NIST/NASA Working Group for the

Development of Test Methods and Specifications for 356 mm Ruggedized Rewritable

Media. The test methods were developed for 356 mm two-sided laminated glass

substrate with a magneto-optic active layer media technology. These test methods

may be used for testing other media types, but in each case their applicability must be

evaluated. Test methods are included for a series of different media characteristics

including: operational, non-operational, and storage environments, mechanical and

physical characteristics, and substrate, recording layer, and preformat characteristics.

Tests for environmental qualification and media lifetimes are also included. The test

methods include testing conditions, testing procedures, a description of the testing

setup, and the required calibration procedures.

Key words: erasable media, magneto-optic media, media lifetime, optical disk media,

ruggedized optical media, test methods.

XV

Chapter 1

General

1.1 Scope

This publication specifies test methods for media characteristics of ruggedized optical

disks with 356 mm two-sided laminated glass substrate with a magneto-optic active

layer used for information processing systems and for information storage. These test

methods can be used to measure quantities frequently given in a media specifications

document. In an effort to maintain generality, in many cases specific numbers are not

given. Instead, the reader is referred to the appropriate media specifications document.

These test methods may be appropriate for other media. Their applicability must be

evaluated on a case by case basis.

1 .2 Purpose

This publication provides test methods and test procedures for media characteristics.

These procedures may be used to verify conformance with a related media specification

standard or as a guideline for measuring media characteristics of the type described

in section 1.1.

1 .3 References

Chapter 4 includes a list of publications and standards. Some of the standards contain

information which, through references in this text, constitute provisions of this

publication. At the time of publication, the indicated editions of these standards were

valid.

1
1 .4 Definitions

Collected Volatile Condensable Material (VCM) - (see sec. 3.4.2)

Quantity of outgassed material from a test specimen tliat condenses on a collector

maintained at a specific constant temperature for a specified time. VCM is expressed

as a percentage of the initial specimen mass and is calculated from the condensate

mass determined from the difference in mass of the collector plate before and after the

test.

Total Mass Loss (TML) - (see sec. 3.4.2)

Total mass of material outgassed from a specimen that is maintained at a specified

constant temperature and operating pressure for a specified time. TML is calculated

from the mass of the specimen as measured before and after the test and is expressed

as a percentage of the initial specimen mass.

Dynamic Axial Runout - (see sec. 3.5.4)

The dynamic axial runout is the peak-to-peak axial deflection of the disk measured

while rotating the disk according to the test conditions.

Dynamic Radial Runout - (see sec. 3.5.7)

The dynamic radial runout is the peak-to-peak radial deflection of the features used to

define a track as the disk rotates.

Droop - (see sec. 3.5.10)

Droop is the axial displacement of the recording layer between the disk inner recording

radius and the outer recording radius.

2
Chapter 2

Testing Conditions

All of the following test methods assume that the testing systems are under statistical

control.

2.1 General Environment

Unless otherwise specified, tests and measurements made on the optical disk to check

the requirements of this publication shall be carried out in an environment where the

air immediately surrounding the optical disk is under the conditions shown in table 2.1.

Table 2.1. General environment

Parameter Value

Temperature 23 "C ± 2 -C

Relative humidity 45% to 55%

Atmospheric pressure 7.5 * 10^ Pa to 10.5 * 10^ Pa

Air cleanliness Class 100,000

The optical disk shall be conditioned in this environment for 24 hours minimum before

any testing. No condensation on the optical disk shall occur.

3
2.2 Measurement Precision

A property is in conformance witti a specification if and only if:

LSL + 3s < X < USL - 3s

where, x is the measurement of the property in question, LSL is the lower specification

limit, USL is the upper specification limit and s is the sample standard deviation of the

measurement. If only one specification limit is given, then only the condition for that

limit need be met.

2.3 Mechanical

a) Figure 2.3.a shows a disk plan view, where OD is the outside diameter and ID

is the inside diameter. R1 is the write/read area outer radius, R2 is the

write/read area, inner radius, R3 is the outer clamping radius, and R4 is the

inner clamping radius.

Figure 2.3.a. Disk plan view.

4
The surface which contacts the optical disk at the clamp zone during testing,

shall have a maximum axial and radial runout of 0.05 iim (see fig. 2.3. a and

2.3.b). The finish of the surface which contacts the optical disk at the clamp

zone shall have a maximum arithmetic average of 0.4 /xm.

A clamping force F within the following range shall be applied uniformly over the

clamp zone.

667 newton < F < 1557 newton

Accepted industry practice shall be used to measure the clamping force.

Clamping Method

Any clamping method that accomplishes the requirements of section 2.3.b and

2.3.C shall be used. An illustration of one such method is shown in figure 2.3.b.

Figure 2.3.b. Disk clamping method.
2.4 Recording

2.4.1 General

There are test conditions specified for two recording objectives of different numerical

apertures (NA):

Test condition A: for NA = 0.60

Test condition B: for NA = 0.68

Unless otherwise specified the test condition applies for test conditions A and B.

6
Table 2.4.1. Testing conditions

Parameter Value or condition

Notes:

Environment

Wavelength

Wave!ength/NA for

test condition A

Waveiength/NA for

test condition B

Filling of the lens aperture D/W (1)

Wavefront at the disk (2):

Third order astigmatism

Third order coma

Third order spherical aberration

Detection method

Extinction ratio

Rotational frequency of the disk

See section 2.1

830 nm ± 20 nm

1.38 nm ± 0.03 fim

1.22 jum ± 0.02 /xm

1.0 max.

< 0.13

< 0.10

< 0.35

Differential (see app. A)

0.01 max. (see app. A)

18.0 Hz ± 0.2 Hz

In the parameter filling of the lens aperture, D is the diameter of the lens aperture

and W is the l/e^ beam diameter of the gaussian beam.

For the wavefront at the disk, the total RMS wavefront variance shall be <. 0.046. Coma is the most significant aberration affecting performance. An optical

system providing a Strehl ratio of 0.92 while meeting the specification for coma

will be adequate for these test methods.

7
2.4.2 Read Conditions

The read power shall be 2.0 mW.

2.4.3 Write Conditions

a) For those test methods that require writing a track with the optimum write power,

the write power shall be as determined by the test method described in section

3.7.9.

b) For those test methods in section 3.7 that require a write power range, tests are

to be performed in the range of 4 mW to 12 mW.

c) Marks are written on to the disk by pulses of optical power superimposed upon

a specified bias power of 2.0 mW.

d) The pulse shape shall be as specified in appendix B.

e) The write power is the optical power incident at the entrance surface of the disk.

f) The magnetic field intensity used to write shall be between 18 000 A/m and

32 000 A/m. The write magnetic field shall be normal to the recording surface

(±5°). The direction of the write magnetic field shall be from the entrance

surface to the recording layer.

2.4.4 Erase Conditions

a) The erase power shall be the optimum write power as defined by the test

method described in section 3.7.9. The required power shall not exceed 12 mW.

b) The magnetic field intensity used to erase written marks shall be between

18 000 A/m and 32 000 A/m and shall be normal to the recording surface (±

5°). The direction of the magnetic field shall be from the recording layer to the

entrance surface.

8
Chapter 3

Test Methods

3.1 Operational Environment Test

The operational environment is the environment encountered when the optical disk is installed in the drive and the drive is operating. Therefore all operational environment

testing on the optical disk will be performed while the optical disk is spinning. The

rotational rate of the disk is specified in section 2.4.1. All "Operational Environment"

tests are performed by first testing some media characteristics and then, while exposing

the disk to the operational environment, retesting the media characteristics to observe

any change in the originally measured parameter. Unless otherwise specified, the

parameters listed in table 3.1 shall be measured before and after each test.

Table 3.1. Parameters for the operational, non-operational, and

storage environment tests

Test Section Number

Dynamic Axial Runout

Axial Acceleration OR

Residual Focus Error

Dynamic Radial Runout

Radial Acceleration OR

Residual Tracking Error

Droop

3.5.4

3.5.5

3.5.6

3.5.7

3.5.8

3.5.9

3.5.10

3.5.11

3.7.11

Tilt Raw Error Rate

9
3.1.1 Thermal

1) General

Thermal cycling between temperature extremes is performed to verify performance at other than stabilized conditions including level extremes and temperature gradient shifts,

thus inducing stress intended to uncover incipient problems. For this test the disk (and

only the disk) is heated while it is rotating. This may be done by using infrared lamps

shining on the disk or by using a special chamber to house the disk (the chamber shall

have a small slot to allow the laser beam(s) to reach the disk, an opening for the drive

shaft, and be capable of being heated). Additional apparatus consists of auxiliary

instrumentation capable of maintaining and continuously monitoring the required

conditions of temperature of the air surrounding the test disk.

2) Test Procedure

a) Continuous recording of the disk and chamber temperature (if applicable) is required. The disk temperature may be measured by use of an infrared

pyrometer (preferred) or approximated by placing a thermocouple very near the

disk surface and away from any heat lamp (if applicable).

b) • Thermally cycle the disk per figure 3.1.1 to the levels specified in the appropriate

media specifications document.

time

Figure 3.1.1. Thermal cycle.

10
Figure 3.1.1 includes the following parameters:

^hot • upper temperature limit

^coid • 3fT^bient temperature

^rate

" ternpe^ature rate of change

*hoid • temperature bounds

n : number of cycles

The tolerances for the temperature and temperature rate are:

Temperature: ±2 -C

Temperature rate: ±10%

3.2 Non-operational Environment Test

The non-operational environment is the type of environment encountered when the

optical disk is installed in the drive and the drive is not operating (examples: spacecraft

integration, prelaunch, spacecraft launch, spacecraft landing). The optical disk is not

spinning during the non-operational environment tests. All "Non-Operational

Environment" tests are performed by first testing some media characteristics, then

exposing the disk to the non-operational environment and subsequently retesting the

media characteristics to observe any change in the originally measured parameter.

Unless otherwise specified, the parameters listed in table 3.1 shall be measured before

and after each test.

3.2.1 Thermal

1) Test Setup

The required apparatus consists of a chamber or cabinet together with auxiliary

instrumentation capable of maintaining and continuously monitoring the required

conditions of temperature throughout the envelope of air surrounding the test disk.

2) Test Procedure

a) The thermal chamber may be at ambient pressure with a chamber environment

of air or gaseous nitrogen.

b) The thermal chamber shall be examined to ensure that it is not a contributing

source of contamination.

11
c) Continuous recording of the chamber and disk temperature is required.

d) To avoid condensation, the test shall begin and end with a hot soak.

e) in the thermal chamber, temperature cycle the disk according to the cycle shown

in figure 3.1.1, to the levels specified in the appropriate media specifications

document with the following tolerances:

Temperature: ±2 »C

Temperature rate: ±10%

3.2.2 Humidity

Perform the humidity test per Mil-Std-810E Method 507.3, Procedure III.

3.2.3 Temperature-Altitude

1) Test Setup

The required apparatus consists of a thermal/vacuum chamber with auxiliary

instrumentation capable of maintaining and continuously monitoring the required

conditions of temperature and pressure throughout the envelope surrounding the test

disk.

2) Test Procedure

a) The thermal/vacuum chamber shall be examined to ensure that it is not a

contributing source of contamination.

b) Continuous recording of the chamber temperature and pressure and disk

temperature is required.

c) Evacuate the thermal/vacuum chamber to the pressure specified in the

appropriate media specifications document.

d) In the thermal/vacuum chamber, temperature cycle the disk per figure 3.1.1 to

the levels specified in the appropriate media specifications document with the

following temperature and pressure tolerances:

12
Temperature:

Temperature rate: ±2 -C

±10%

Pressure:

Greater than 1.33 * 10"^ Pa : 1.33 * 10^ Pa to 1.33 * 10^ Pa : 1.33 * 10^ Pa to 1.33 * 10"'' Pa : Less than 1.33 * 10'"^ Pa :

+ 5%, -0%

±10%

±25%

+0%, -80%

3.2.4 Vibration

1) Introduction

The disk shall be subjected to random vibration along axes normal to the disk plane

and parallel to the disk plane.

2) Test Setup

The disk shall be mounted to the test equipment by a rigid test fixture. The test fixture

shall provide uniform clamp force over the clamp zone as shown in figure 2.3.a. For

the purpose of controlling the vibration, calibrated accelerometer(s) shall be attached

rigidly on the test fixture near the test fixture/disk interface and aligned with the axis of

the applied vibration.

This test method has no requirements for response accelerometer(s). If however,

response accelerometer(s) are used, it is not recommended to mount them directly to

the glass disk as this may cause damage to the disk when removing the

accelerometer(s). It is advised to apply a strip of Kapton pressure sensitive tape

(example: 3M Scotch 5413 Kapton Film Tape or equivalent) to the glass disk, and

mount the response accelerometer to the tape.

3) Test Procedure

With the disk mounted on the vibrator, initially perform a 1 g RMS random survey over

the frequency band (listed in the appropriate media specifications document) to evaluate

test setup and disk response. Perform the random vibration according to the

specification listed in the appropriate media specifications document. The excitation

spectrum, as measured by the control accelerometer (s), shall be equalized such that

the overall RMS level is within ±10% of that specified. The power spectral density shall

Note:

13
be within ±3dB of tine specified levels everywhere in the frequency band.

3.3 Storage Environment Test

In the storage environment the optical disk is not installed in the drive device, but

stored in it's own handling container. All "Storage Environment" tests are performed by

first testing some media characteristics, then exposing the disk to the storage

environment, and subsequently retesting the media characteristics to observe any

change in the originally measured parameter. Unless otherwise specified, the

parameters listed in table 3.1 shall be measured before and after each test.

3.3.1 Thermal

Using the test method described in section 3.2.1, thermally cycle the disk using the

specifications listed in the appropriate media specifications document.

3.3.2 Humidity

Perform the humidity test per MIL-STD-810E Method 507.3 Procedure III.

3.3.3 Temperature-Altitude

Using the test method described in section 3.2.3, perform temperature-altitude tests

using the specifications listed in the appropriate media specifications document.

3.4 Environmental Qualification

These tests are performed only on sample optical disk(s). The tests are to qualify the

disk design for space flight. The optical disk(s) used for environmental qualification

tests are to be of the same design and manufacturing process as deliverable disks.

Optical disk(s) which have undergone environmental qualification tests cannot later be

used as deliverable disks. A deliverable optical disk has had its design qualified, but

has not undergone environmental qualification testing. All "Environmental Qualification"

tests are performed by first testing some media characteristics, then exposing the disk

to the environmental qualification environment, and subsequently retesting the media

characteristics to observe any change in the originally measured parameter.

14
3.4.1 Radiation

1) Introduction

The parameters listed in table 3.4.1 shall be measured before and after each test:

Table 3.4.1. Parameters for the radiation test

Test Section Number

Reflectance 3.7.1

Narrow Band Signal-to-noise Ratio 3.7.6

Ease of Erasure 3.7.8

Optimum Write Power 3.7.9

Mark uniformity 3.7.10

Raw Error Rate 3.7.11

Note:

For the case where sections of the surface are exposed to radiation, the test methods

shall be conducted only over that region. For all the tests the section of the surface

exposed shall be large enough to give statistically significant results.

2) Gamma Radiation Test Procedure

Expose a disk's recordable surface (or a section of the surface) to a cobalt-60 source

for a sufficient duration to achieve a gamma radiation dose equal to (or greater than)

the level listed in the appropriate media specifications document. Visible discoloration

of the optical disk after the gamma radiation test is not an indication of passage or

failure of this test.

3) Electron Radiation Test Procedure

Expose a disk's recordable surface (or a section of the surface) to an electron radiation

source for a sufficient duration to achieve an electron radiation dose equal to (or

greater than) the level listed in the appropriate media specifications document. Visible

discoloration of the optical disk after the electron radiation test is not an indication of

passage or failure of this test.

15
3.4.2 Thermal Vacuum Stability Test (Outgassing)

1) IntrcxJuction

Due to possible contamination to the spacecraft, astronauts and other equipment,

nonmetallic materials for spaceflight applications must be contained in an

environmentally sealed container or pass stringent thermal vacuum stability tests. Since

outgassing test chambers are usually quite small, the outgassing test shall be performed

on the separate material compounds or components which comprise the optical disk.

There are no media characteristics tests before or after the outgassing test.

Note:

If the material has previously been tested and is listed in the NASA MSFC-HDBK-1674

"Compilation of TVS Data for Nonmetallic Materials" [3], then the material does not have

to be tested again.

2) Test Procedure

The Thermal Vacuum Stability Test shall be conducted per requirements of SP-R-0022

"Vacuum Stability Requirements for Polymeric Materials for Spacecraft Applications"[4],

and ASTM E 595-84, "Test Method for Total Mass Loss and Collected Volatile

Condensable Materials from Outgassing in a Vacuum Environment"[5]. For the

maximum allowable TML and VCM see the specifications listed in the appropriate media

media specifications document.

3.4.3 Vibration

1) General

Using the test method described in section 3.2.4, randomly vibrate the disk using the

levels listed in the appropriate media specifications document.

The parameters listed in table 3.1 shall be measured before and after the test.

16
3.4.4 Thermal Cycling

Using the test method described in section 3.2.1, thermally cycle the disk using the

specifications listed in the appropriate media specifications document.

The parameters listed in table 3.4.4 shall be measured before and after the test.

Table 3.4.4. Parameters for the thermal cycling test

Test 55pptinn Niimhpr

Uyr idlTIIO rVXIal nUuOUl 'i A

AVAIctl MLrOcim dllUi 1 \JT\ O.D.D 1 R

Residual Focus Error 3.5.6

Dynamic Radial Runout 3.5.7

Radial Acceleration OR 3.5.8

Residual Tracking Error 3.5.9

Droop 3.5.10

Tilt 3.5.11

Narrow band Signal-to-noise Ratio 3.7.6

Crosstalk 3.7.7

Ease of Erasure 3.7.8

Optimum Write Power and Sensitivity 3.7.9

Mark Uniformity 3.7.10

Raw Error Rate 3.7.11

Push-pull Signal 3.8.1

Preformat Data Signal 3.8.3

3.4.5 Temperature-Altitude

Using the test method described in section 3.2.3, perform temperature-altitude tests

using the specifications listed in the appropriate media specifications document.

17
3.5 Mechanical and Physical Characteristics

3.5.1 Dimensions of the Disk

Accepted industry practice shall be used to measure the dimensions of the disk.

3.5.2 Moment of Inertia

1) Test Procedure

a) Suspend the optical disk by three cords as shown in figure 3.5.2.

Figure 3.5.2. Moment of inertia test setup.

b) Start the disk oscillating by rotating it not more than 45 degrees from the rest

position.

c) At a convenient point during the oscillation, begin timing until 100 oscillations

have been completed. One oscillation is defined as the time required for the

disk to rotate one complete cycle from the starting point until it reaches the

starting point again by rotating in the same direction.

d) Determine the moment of inertia from the following expression:

18
7.06 * W * *

I =

I

where: I is the moment of inertia (in kg*m^), W is the weight (in newton), r is the radius

at which the suspending cords are attached (in meters), T is the time for one complete

oscillation (in seconds), and I is the length of cords (in meters)

Note:

The support shall be sufficiently flexible so as not to impede rotation.

3.5.3 Imbalance

Imbalance of the disk can cause excessive radial runout and corrupt linear velocity

uniformity. Testing the imbalance of the disk requires the use of commonly available

dynamic balancing equipment. Imbalance testing should be conducted at the highest

operating angular velocity (RPM) for the system as specified in the appropriate media

specification document.

3.5.4 Dynamic Axial Runout

1) Introduction

The dynamic axial runout shall be measured using the system shown in figure 3.5.4.

For frequencies below the resonance of the focus actuator the transfer function is constant and the actuator drive current is proportional to the axial position of the

focused spot. Under these conditions, and when a servo system is used to maintain

focus, the drive current is also proportional to the disk surface position, provided the

focus error signal is sufficiently small.

2) Calibration

a) Actuator Drive Curnent

While using a servo system to maintain focus on a stationary disk, vary the distance

between the optical head and the disk. Measure the distance with an accuracy of

better than 0.25Aim. Record the actuator drive current as a function of head-disk

distance. The ratio of displacement to drive current is equal to K^/K^.

19
b) Residual Focus Error

With the focus servo off, mechanically adjust the optical head to bring a stationary disk

into focus. Vary the distance between disk and the head, both above and below the

focus position. Measure the distance to an accuracy of better than 0.25/im and record

the error signal as a function of distance.

3) Test Conditions

Measurements shall be taken at three separate radii: 110 mm, 140 mm, and 170 mm.

Axial Media

Position

Spot

Position

Qain,

Compensation,

Current Driver

8^+ A«8+B

(Actuator)

Runout

Signal

R(t)

s^ + A.s + B

(Filter)

Acceleration

Signal

A(t)

High-pass Filter, 1600 Hz, LP Filter

Figure 3.5.4. Dynamic axial runout block diagram.

20

4.
4) Test Procedure

a) Obtain the actuator transfer function. Define a filter network with the same

denominator as the actuator mass-spring-damper system (parasitic resonances

are ignored)

Note:

For frequencies below the resonant frequency of the actuator this step can be ignored.

b) While using a servo system to maintain focus, measure the peak-to-peak actuator

drive current during a revolution of the disk.

c) The displacement equals the peak-to-peak drive current times K^/K^, where K^/K^

is determined by the calibration procedure.

d) When using this method, the maximum residual focus error shall correspond to

a displacement of less than 1% of the maximum runout specified in the

appropriate media specifications document.

3.5.5 Axial Acceleration

1) introduction

The actuator current is proportional to the acceleration of the lens, when considering

frequencies above the natural frequency of the actuator.

2) Calibration

Calibration of acceleration requires the determination of (K1/K2) as explained in section

3.5.4 in the calibration of the dynamic axial runout. K2 is determined by inspection of

the filter.

3) Test Conditions

Measurements shall be taken at three separate radii: 110 mm, 140 mm, and 170 mm.

4) Test Procedure

a) Choose a band-pass filter with characteristics such that the lower frequency limit

is 30 Hz, when taken in series with the natural frequency characteristics of the

actuator. Unlike the upper specified frequency limit of 1500 Hz, the lower

21
frequency limits are not critical at all (in fact, it may be shown that a disk must

be significantly over the runout specification at 30 Hz to exceed the 30 Hz

acceleration specification). The filter shall be a 4th-order maximally flat ("Butterworth") filter. Appendix C shows an example of this implementation.

b. By expressing the constant K1 in terms of the measurable quantities K1/K2 and

K2, the acceleration signal A(t) is related to the acceleration of the media, as

follows:

Acceleration of the media = A(t) * (K1/K2) * K2

3.5.6 Residual Focus Error

1) Introduction

Residual focus error can be caused by thickness variations in the substrate as well as dynamic axial runout and acceleration of the disk. Furthermore, it is necessary to

measure the completed optical disk assembly to assure compliance with the

specification for residual focus error in the appropriate media specifications document.

Residual focus error for the optical disk shall be measured using the system shown

in concept in figure 3.5.6.

The closed loop focus servo system shall have sufficient bandwidth such that the

residual focus error signal provides a linear, high-resolution measurement of disk

position. A position sensor is employed to provide a high resolution measurement of

the focusing lens position, therefore also the disk. This sensor can be an

interferometer, or an optical, capacitive, or electromagnetic device with bandwidth at least equal to that of the low performance servo system. When the residual focus

error signal is added to the lens position sensor signal, an exact measure of the

position of the disk is achieved. This disk position signal shall then be processed by

a digital or analog filter whose disturbance rejection transfer function is given in equation

3.5.6. The output of the filter is a measure of the residual focus error produced by

such a "standardized" servo system.

Equation 3.5.6:

Residual focus error 1

Disk position G * w^^ * (s/a + 1)

(or Apparent deviation) 1 +

(s/b + 1) * (s^ + 2 * z * w^ * s + W|

22
G = 400

b = (2 * TT * 5600) in rad/s

a = (2 * TT * 700) in rad/s = (2 * TT * 40) in rad/s z = (zeta) 0.2 typ. s = a

* 2 * IT * freq.) LaPlace Transform operator

Laser

Low

Performance

Focus Servo

Lens

Position

Sensor

Lens (Disk) Position

Msasured Rasldual Focus Error Signal

Disturbance

Re|ectlon

Simulator

Simulated

Residual Focus Error

Figure 3.5.6. Residual focus error test system.

Calibration

Employ a translation stage to move the measurement system relative to a

suitable stationary reflector with a reflectance similar to that of the disk.

With the measurement system positioned at the center of the focus error signal

range, and the focus servo loop open, translate the measurement system a known distance within the linear range of the focus error signal detector to

calibrate its output as a function of distance. The translation stage shall be

accurate to better than .25)um.

Return the measurement system to the center of the focus signal range and

close the focus servo loop.

23
d) Translate the measurement system a known amount to calibrate the lens position

detection system as a function of distance.

e) Replace the stationary reflector with the optical disk.

3) Test Conditions

Measurements shall be taken at three separate radii: 110 mm, 140 mm, and 170 mm.

4) Test Procedure.

Measure the peak-to-peak residual focus error.

3.5.7 Dynamic Radial Runout

1) Introduction

The dynamic radial runout shall be measured using the system shown in figure 3.5.7.

For frequencies below the resonance of the radial actuator, the transfer function is constant and the actuator drive current is proportional to the radial position of the

focused spot. Under these conditions, and when a servo system is used to maintain

tracking, the actuator current is also proportional to the radial position of the tracking

feature, provided the radial error signal is sufficiently small.

2) Calibration

a) Actuator Drive Current

Acquire tracking on a stationary disk. Vary the relative radial position of the

head and the tracking feature with an accuracy of better than O.IOjum. Record

the actuator current as a function of relative position. The ratio of displacement

to drive current is equal to K^/K^.

b) Tracking Error Signal

With the disk spinning, and the track servo open, calibrate the oscilloscope

time base by measuring the track pitch as the distance between track crossings

of the track error signal. Calibrate the timebase, in micrometers, by measuring

the minimum time between track crossings. The track pitch is measured by the

procedure in section 3.8.4. Calibrate the track error signal by obtaining the

24
voltage per unit distance ratio over the linear portion of the tracking s-curve.

3) Test Conditions

Measurements shall be taken at three separate radii: 110 mm, 140 mm, and 170 mm.

4) Test Procedure

a) Obtain the actuator transfer function. Define a filter network with the same

denominator as the actuator mass-spring-damper system (parasitic resonances

are ignored).

Note:

For frequencies below the resonant frequency of the actuator this step can be ignored.

b) While using a servo system to maintain tracking, measure the peak-to-peak radial

actuator drive current during a revolution of the disk.

c) The displacement equals the peak-to-peak actuator current times K^IK^, where

K^/K^ is determined by the calibration procedure

d) When using this method, the maximum residual tracking error shall correspond

to a displacement of less than 1% of the maximum runout specified in the

appropriate media specifications document.

25
Radial Media

Position

4-

Spot

Position

1 Qain,

Compensation,

Current Driver

1

s'^* A«8 + B (Actuator)

Runout

Signal

R(t)

s^+AtS+B

(Filter)

Acceleration

Signal

A(t)

Figure 3.5.7. Dynamic radial runout block diagram.

3.5.8 Radial Acceleration

1) Introduction

The actuator current is proportional to the acceleration of the lens, when considering

frequencies above the natural frequency of the actuator.

2) Calibration

Calibration of acceleration requires the determination of (K1/K2) as explained in section

3.5.7 in the calibration of dynamic radial runout. K2 is determined by inspection of the

filter.

3) Test Conditions

Measurements shall be taken at three separate radii: 110 mm, 140 mm, and 170 mm.

Hlgh-paaa Flltar, 1S00 Hz. LP Filter

26
4) Test procedure

a) Choose a band-pass filter such that the lower frequency limit is 30 Hz, when

taken in series with the natural frequency characteristics of the actuator. Unlike

the upper specified frequency limit of 1500 Hz, the lower frequency limits are not critical (in fact, it may be shown that a disk must be significantly over the

runout specification at 30 Hz to exceed the 30 Hz acceleration specification).

The filter shall be a 4th-order maximally flat ("Butten/vorth") filter. Appendix C

shows an example of this implementation.

b) By expressing the constant K1 in terms of the measurable quantities K1/K2 and

K2, the acceleration signal A(t) is related to the acceleration of the media, as

follows: acceleration of the media = A(t) * (K1/K2) * K2.

3.5.9 Residual Tracking Error

1) Introduction

The residual tracking error signal is the result of the tracking servo system's

inability to perfectly reject disturbances. The sources of these disturbances are numerous and include dynamic radial runout, radial acceleration and vibration.

Residual tracking error shall be measured using the system shown in concept in figure

3.5.9. The closed loop tracking servo system shall have sufficient bandwidth such that

the residual tracking error signal provides a linear, high resolution measurement of

track position. A position sensor is employed to provide a high resolution

measurement of the tracking lens position, therefore also the track. This sensor can

be an interferometer, or an optical, capacitive, or electromagnetic device with

bandwidth at least equal to that of the low performance servo system. When the

residual tracking error signal is added to the lens position sensor signal, an exact

measure of the position of the track is achieved. This track position signal is then

processed by a digital or analog filter whose disturbance rejection transfer function is given in equation 3.5.9.:

Residual tracking error 1

Actual deviation G * w^^ * (s/a + 1)

1 +

(s/b + 1) * (s^ + 2 * z * w^ * s + w^^^

27
where:

G = 400

b = (2 * TT * 5600) in rad/s a = (2 * TT * 700) in rad/s = (2 * TT * 40) in rad/s z = (zeta) 0.2 typ. s = (j*2*7r* freq.) LaPlace Transform operator

Laser

Low

Performance

Tracking Servo

Lens

Position Sensor

Test Disk

Measured Residual Tracking Error Signal

Lens (Track)

Position

Disturbance

Rejection

Simulator

simulated

Residual

Tracking

Error

Figure 3.5.9. Residual tracking error test system.

2) Calibration

With the disl< spinning, and the track servo open, calibrate the oscilloscope time base

by measuring the track pitch as the distance between track crossings of the track

error signal. Calibrate the timebase, in micrometers, by measuring the minimum time

between track crossings. The track pitch is measured by the procedure in section

3.8.4. Calibrate the track error signal by obtaining the voltage per unit distance ratio over the linear portion of the tracking s-cun/e. Return the measurement system to the

center of the tracking signal range and close the servo loop. Translate the

measurement system a known amount to calibrate the lens position detection system

as a function of distance.

28
3) Test Conditions

Measurements shall be taken at three separate radii: 110 mm, 140 mm, and 170 mm.

4) Test Procedure

Measure the peak-to-peak residual tracking error.

3.5.10 Droop ,

1) Test Procedure

Measure the DC level of the dynamic axial runout according to the test method

described in section 3.5.4 at the inner and outer radius of the recording area. The

droop is the difference between these two measurements.

3.5.11 Tilt

1) Introduction

The tilt of the disk surface shall be measured by using an auto collimator or similar

apparatus as shown in figure 3.5.11. In general, a collimated light source is projected

at a surface. When the surface is perpendicular to the optical path, the collimated

beam is reflected on axis, and viewed relative to the reference axes in the viewport.

2) Calibration

The system is calibrated by using a precision optical test flat on the spindle and a tilt stage. Tilt the test flat (or autocollimator) a known amount which can be calculated

from the geometry of the set-up. Note the position of the reflected beam in the view

port.

3) Test Procedure

a) Mount a precision optical test flat on the spindle and align the system such

that the reflected beam is centered relative to the reference axes in the auto

collimator view port.

b) Mount the disk to be tested on the spindle in place of the precision optical test

flat and note the relationship of the reflected beam to the reference axes.

29
c) Slowly rotate the disk and translate the spindle (or auto collimator) to examine

the tilt of the disk surface.

Radial Translation

Figure 3.5.11. Tilt test setup.

3.6 Substrate Characteristics

3.6.1 Index of Refraction

The test of index of refraction is an accepted industry practice.

3.6.2 Double-pass Retardation

1) Test Procedure

a) The double-pass retardation (2 ) shall be measured by placing the sample in an optical isolator comprising a polarizer (P), a quarter wave plate (QWP)

oriented at 45°, and a mirror (M). When a birefringent sample is placed in the

optical path between the QWP and the mirror, the intensity of the reflected

beam which leaks back through the polarizer is proportional to sin^(25). Figure

3.6.2. shows an optical layout for implementing this method with a transparent

substrate. A laser beam passes through a beam splitter (BS), a polarizer, an

oriented QWP, and is reflected by a mirror back to the photodetector (D1). By

30
tilting the substrate (S), measurements can be made at non-norma! incidence,

b) The measurement shall be made at normal incidence and at an angle of 30°.

2) Calibration

Calibration of the signal can be accomplished by rotating the QWP a known angle

away from 45° and measuring the detector output in the absence of a birefringent

sample.

Figure 3.6.2. Double-pass retardation test setup.

3.6.3 Thickness

The test of thickness is an accepted industry practice.

3.7 Recording Layer Characteristics

3.7.1 Reflectance, Uniformity of Reflectance, and Rate of Change of

Reflectance

1) Introduction

The output of the DC coupled RF preamplifier or the sum of the preamplified focus

31
cell outputs, hereafter refer to as the output, will be used to measure baseline

reflectance and uniformity of baseline reflectance.

2) Calibration.

To calibrate the system, measure the output to determine the DC voltage (VJ

corresponding to 0% reflectance (i.e., laser off) and the voltage from a sample of

known reflectance (R^) at the testing wavelength, while in focus under the head. Then,

for the disk sample with measured voltage V^, the disk reflectance is equal to:

Ro *(v„-v„)

3) Test Procedure

a) Reflectance: Measure the output while focused over a smooth area of the

rotating disk. This measurement shall be used to determine both the average

level and uniformity of reflectance. The average reflectance is defined as the

average of reflectance values measured at five radii equally spaced over the

recordable area.

b) Uniformity of reflectance: it is determined calculating the difference between the

maximum and minimum values measured in any of the five equally spaced radii.

c) Rate of change of reflectance: For each of the equally spaced radii, determine

the difference between the maximum and minimum values of reflectance. The

rate of change of reflectance (R/s) is the maximum of those five values

multiplied by the rotation rate.

3.7.2 Resolution

1) Introduction

The measurements shall be performed at five radii equally spaced over the recordable

area.

2) Test Procedure

a) Record a 50% duty cycle tone at the optimum write power at the lowest and

the highest frequency specified in the appropriate media specifications

document.

32
b) Measure the carrier amplitude in a 30 kHz bandwidth using a spectrum analyzer

for both the high frequency and the low frequency carriers mentioned in paragraph (a). The resolution is defined as the ratio of the high frequency

carrier amplitude to the low frequency carrier amplitude.

3.7.3 Imbalance of the Magneto-optic Signal

1) Introduction

The measurements shall be performed at five radii equally spaced over the recordable

area.

2) Test Procedure

The imbalance of the magneto-optic signal shall be measured using the optical system

described on appendix A. Imbalance is defined as the ratio of the maximum DC

offset (a) of the readback signal to the average peak-to-peak signal amplitude along

the track S (see figure 3.7.3.)

3.7.4 Disk Retardation

1) Introduction

The measurements shall be performed at five radii equally spaced over the recordable

area.

Ov

DC Level

Figure 3.7.3. Imbalance of the magneto-optic signal.

33
This test method measures the phase difference between s and p polarization reflected

from the disk. Such phase shifts are typically caused birefringence in the substrate.

Reflection from the active layers at non-normal incidence can also cause these phase

shifts, independent of the magneto-optical effect. These effects are conventionally

quantified as a retardation s in nm.

2) Test Instrument

Figure 3.7.4 shows the setup for the measurement of disk retardation. The

measurement consists of placing the disk in an optical isolator consisting of a

polarization beam splitter (PBS), a polarization analyzer (PA) and two quarter wave

plates (QWP^ and QWPj) oriented at 30° with respect to the analyzer. The system

is illuminated with collimated laser light of the wavelength given in table 2.4.1.

Laser

Figure 3.7.4. Disk retardation test instrument.

3) Calibration

Rotating QWP^ through a small angle e corresponds to introducing a phase shift

$ = 2g into the beam to detector and $ = 4e into the beam to D^. The intensity

of light on detectors and D2 shall be measured as a function QWP^ angle e.

1 34
A plot of 6 = 2e times lambda over 2n versus the intensity on D2 and a plot of

5 = 4e times lambda over 2ir , versus the intensity on gives the calibration.

4) Test Procedure

The measurement consists of determining the light intensity on detector for normal

incidence, and on detector D2 at an incidence angle of 30°. For a system with no

phase difference between s and p light (and assuming perfect polarizers) no light

should reach the detectors. These two measurements are converted to a retardation

at normal incidence and a retardation at 30°, using the instrument calibration.

3.7.5 Figure of Merit

1) Introduction

The figure of merit F, is the product of R, sin e,^ and cos 2e,^, where R is the

reflectance expressed as a percentage, e,^ is the Kerr rotation and e,^ is the ellipticity

of the reflected beam.

The polarity of the figure of merit is defined to be negative for the written mark in an

Fe-rich Fe-Tb alloy layer with the write magnetic field in the direction specified in section 2.4.3. The direction of Kerr rotation is counterclockwise as seen from the

incident beam. The measurement shall be made with a direct measurement of e,^ and

and with a conversion from the signal amplitude of written marks (see appendix B).

The figure of merit is, in practice, equal to the amplitude of the read signal from a

recording at low frequency (in two dimensions). The written domains shall be

substantially larger than the focal spot, so as to work in the low frequency region

where the modulation transfer function of the optical system is one. This implies that

a disk, rotating at 30Hz, a signal with a frequency between 10 kHz and 100 kHz has

to be written on several consecutive tracks and in between those tracks.

Determination of the figure of merit using an optical system as shown in appendix A

and with the characteristics as specified in section 2.4.1, will not measure media

properties only but also the optical retardation of the optical system. Therefore the

calibration of the optical system is needed with a conventional determination of the

figure of merit by measuring the reflectance, Kerr rotation and ellipticity. This

calibration can only be executed reliably on media with low coercivity.

35
2) Calibration

The optical test head shall be calibrated as follows:

a) A test disk with negligibie birefringence (glass) and low coercivity magnetooptical layer is used for conventional determination of reflectance R, Kerr

rotation e,^ and ellipticity e,^.

b) Determine: = R * sin e,^ * cos 2e^^

c) Write on ^he same disk a test pattern as described above and read it back with

the optical head resulting in signal amplitude

3) Test Procedure

Any other disk (high or low coercivity) can now be measured with the optical head

using a similar test pattern, resulting in a signal amplitude V. The figure of merit of

the disk now being tested is: F = * VA/^.

3.7.6 Narrow Band Signal-to-noise Ratio

1) Test Conditions

a) The measurement shall be made by writing marks at the minimum specified

feature size, and at the optimum write power as determined by the test method

in section 3.7.9.

b) The measurements shall be taken on an spectrum analyzer with a 30 kHz

resolution bandwidth (RBW).

c) Measurements shall be taken at three separate radii: 110 mm, 140 mm, and

170 mm.

2) Test Procedure

a) Write a test track with a 50% duty cycle tone at the maximum frequency (f^.) given in the appropriate media specifications document and at the proper

rotational frequency to produce the minimum specified feature sizes.

b) Read the test track and measure the signal level using a spectrum analyzer with a center frequency equal to the maximum specified frequency f^. and a

resolution bandwidth of 30 kHz.

36
c) Estimate the noise level by interpolating the average noise floor of the

measurements between f^ - 7 * RBW and + 7 * RBW. c c

d) Calculate the narrow-band signal-to-noise ratio (SNR^J using the following

equation (see figure 3.7.6):

SNR . (dB) = signal power (dBm) - noise power (dBm)

Amplitude Signal Level

Noise Level

Frequency

Figure 3.7.6. Amplitude versus frequency.

3.7.7 Crosstalk

1) Introduction

The track-to-track crosstalk shall be determined by recording a set of three adjacent

test tracks at a pitch specified in the appropriate media specifications document.

2) Test Conditions

a) Measurements shall be made on recordings written at the optimum write power

as determined with the test method described in section 3.7.9.

b) The measurements shall be taken on a spectrum analyzer with a 30 kHz

37
resolution bandwidth. Since there can be track pitch variations as a function

of angle, it is necessary to measure the 6.5 MHz carrier and the 5 MHz signal

power using a spectrum analyzer with zero frequency span capability. With the

analyzer set up for external triggering (the trigger source is once-per-revolution

index pulse), measure the worst case 5 MHz signal content and the

corresponding 6.5 MHz signal content.

c) Measurements shall be taken at three separate radii: 110 mm, 140 mm, and

170 mm.

3) Test Procedure

a) Write a 6.25 MHz tone, at the optimum write power, on the center test track.

b) Write the two tracks on each side of the center track at the track pitch

(+ 0.1 jum/- 0.0 ^m), with a 5.0 MHz tone, at the optimum write power.

c) Read the center test track with a spectrum analyzer with a resolution bandwidth

of 30 kHz.

d) The crosstalk is calculated by the following formula:

5.0 MHz signal power (dBm) - 6.25 MHz signal power (dBm).

3.7.8 Ease of Erasure

1) Test Condition

Measurements shall be taken at three separate radii: 110 mm, 140 mm, and 170 mm.

2) Test Procedure

a) Write a track under the write conditions given in section 2.4.3, and a frequency

rate of 5.0 MHz.

b) Read under the condition specified in section 2.4.2, using a spectrum analyzer

with a center frequency f^ of 5.0 MHz and a resolution bandwidth of 30 kHz.

Note the amplitude of the written marks.

c) Erase the track under the conditions specified in section 2.4.4.

38
Repeat the sequence (a) to (c) 1000 times.

Repeat (a).

Repeat (b); note the signal level of the written marks and of the noise at f^ (see

figure 3.7.6).

Repeat (c); note the residual level of the written marks.

.9 Optimum Write Power

Test Conditions

The testing conditions shall conform to section 2.

The actual write powers, linear velocity, write pulse durations, write/read and

laser spot profiles must be known and corrected during performance of the

tests.

Time domain measurements shall be made using a time interval analyzer with

at least 0.1 ns resolution, (ex: KODE-3100 or equivalent).

Write pulse lengths shall be measured using equipment having rise and fall times of less than one nanosecond.

Measurements shall be taken at three separate radii: 110 mm, 140 mm, and

170 mm.

Time interval boundaries shall be determined by a threshold detection method.

Test Procedure

Erase the test track and adjacent tracks according to the conditions specified

in section 2.4.4.

Write sensitivity and write power range are measured by recording a series of

tracks over a range of write powers that are expected to bracket the optimum

write power.

A 51 1 -bit pseudo-random recording shall be made using the modulation code

and data rate of the system for which this disk is intended. For example using

a (1,7) code at a data rate of 22.5 Mbps produces the following pulse

39
durations: 59.26 ns, 88.89 ns, 118.52 ns, 148.15 ns, 177.78 ns, 207.41 ns, 237.04 ns, 266.67 ns, and 296.30 ns.

The mark length errors for the minimum, maximum and medium mark length

shall be measured by time interval analysis. The errors for each mark length

shall be plotted versus the write power (see fig. 3.7.9). These errors are the

average duration of the mark length from the desired length.

The maximum absolute error curve shall be constructed by plotting the absolute

value of the largest mark length error (from the three mark length error curves) versus each write power (see fig. 3.7.9).

The optimum write power is the power at which the maximum absolute mark

error curve is minimal (see fig. 3.7.9).

The write power range is the range of write powers for which the maximum

mean mark length error curve is less than or equal to 4.0 ns (see fig. 3.7.9).

TIA Power Series

7 8 9 10 11 12 13 14

Power (mW)

Figure 3.7.9. Mark length error versus write power.

40
.10 Mark Uniformity

Test Conditions

The testing conditions shall conform to section 2.

The actual write powers, linear velocity, write pulse durations, write/read and

laser spot profiles must be known and corrected during performance of the

tests.

Time domain measurements shall be made using a time interval analyzer with

at least 0.1 ns resolution, (ex: KODE-3100 or equivalent).

Write pulse lengths shall be measured using equipment having rise and fall times of less than one nanosecond.

Measurements shall be taken at three separate radii: 110 mm, 140 mm, and

170 mm.

Time interval boundaries shall be determined by a threshold detection method.

All recordings shall be made at the optimum write power as determined in section 3.7.9.

Test Procedure

Erase the test track and adjacent tracks according to the conditions specified

in section 2.4.4.

A 511 -bit pseudo-random recording shall be made using the modulation code

and data rate of the system for which this disk is intended. For example using

a (1,7) code at a data rate of 22.5 Mbps produces the following pulse

durations: 59.26 ns, 88.89 ns, 118.52 ns, 148.15 ns, 177.78 ns, 207.41 ns, 237.04 ns, 266.67 ns, and 296.30 ns.

Measure a minimum of 1000 data to clock time intervals.

Obtain the mean and standard deviation.

41
3.7.11 Raw Error Rate

1) Introduction

This test method is used to compare the raw error rate (RER) of the media before,

during, and after the environmental tests in section 3.1 through 3.4.

2) Test Conditions

a) The testing conditions shall conform to section 2.

b) Measurements shall be made on recordings written at the optimum write power

level as determined by the test method described in section 3.7.9.

c) Measurements shall be taken at three separate radii: 110 mm (4.33 in), 140 mm

(5.5 in), and 170 mm (6.69 in).

d) Measurements shall be made with the setup shown in figure 3.7.11.

3) Test Procedure

a) Record a 5.0 MHz tone over a series of 5 tracks of the disk. This produces

the following feature sizes at the three specified radii:

" 1.24 /Ltm at 110 mm, 1.58 /xm at 140 mm, and 1.92 iivn at 170 mm.

b) Read the recording through the test setup shown in figure 3.7.11.

c) Adjust the edge detector to produce 50% duty cycle transitions at the output

with no data input.

d) The error checker shall produce an error output by ex-oring the strobed output

of the clock extractor with that output delayed one clock cycle.

e) Following edge detection, strobe the data with a clock extracted using a phaselock-loop (PLL) characterized by the following transfer function F(s):

K * (s/b + 1)

F(s) = --

s * (s/a + 1) * (s/c + 1)

42
where: K = 63,100,000

a = 2*7r*160 rad/s

b = 2*7r*1 3,300 rad/s c = 2*7r*800,000 rad/s

The PLL's free running frequency shall be adjusted to the output frequency,

10.0 MHz, as close as possible. Adjust the phase delay of the data so that

the strobe point of the clock occurs at the midpoint of the bitcell.

Tone

Qeneretor

(Write)

Counter

Strobed Data

Error Checker Clock

Clock

Extractor Edge

Detector

(Read)

Laaer Head

Figure 3.7.11. Raw error rate test setup.

3.8 Preformat Characteristics

The characteristics of the preformat pattern shall be measured using an optical head

similar to the one depicted in appendix A. In the optical head, some of the light is directed to a photodetector (typically split as shown in fig. 3.8) for the purpose of

detecting track servo signals and preformat data signals.

Characterization of the push pull, track crossing, and preformat data signals as well as the track pitch shall be measured using the optical head with the objective lens

focused onto the disk and the signals defined as follows:

43
: proportional to the reflected intensity from an ungrooved area.

1^, I2 : signals from the two halves of the split detector.

B««m on Ungrooved Area

lo

(II I2)raex

Beam Aoroaa

Traoka

(II -f I2)inln 0 Laval

Light Beam

Saotor Mark Araa ,

Ipd

Photo Olode

Beam on Unrecorded Track

Figure 3.8. Preformat characteristics.

3.8.1 Push-pull Signal

With the disk spinning, track servo open and objective positioned over an ungrooved

area, measure 1^ = (1^ + y^^^. Then, position the objective over a grooved area and

measure the magnitude of the track error signal 1^ - The push-pull ratio is defined

as:

where 1 - I2 1 is the peak-to-peak amplitude of the track error signal.

3.8.2 Track Crossing Signal

With the disk spinning, the objective over a grooved area, and the track servo loop

44
open, measure the track sum signal (1^ + y.

The track cross ratio is defined as:

{(I, + y»x - (I, + y.i„}/io

where (1^ + l^)^^^^ and (1^ + 12)^,-^ are shown in figure 3.8. The maximum track

crossing signal is defined as:

(L + L) /I

^ 1 2' max o

3.8.3 Preformat Data Signal

With the objective lens positioned over a grooved area and the track servo loop

closed, measure the track sum signal (1^ + Ij). As the head scans the track, the

track sum signal modulates in accordance with the prerecorded sector/track

identification. The preformat data signal (Ip^) is defined as:

{('1 + y.ax - di + y.in}/io

3.8.4 Track Pitch

1) Test Procedure

a) With the disk spinning and the track servo locking the objective on track,

measure the displacement of the objective lens using the calibrated actuator

drive current (see sec. 3.5.7, item 2: "calibration").

b) Unlock the track servo, count the number of track crossings observed at the

tracking error signal over one revolution.

c) The track pitch is obtained by dividing the total displacement of the actuator

measured in step (a), by the number of track crossings measured in step (b).

3.9 Media Lifetime

The methods for archival and shelf life assume that the errors are caused by defects

which grow (or become more numerous) according to a first order rate equation, with

45
the rate determined by a single activation energy. Although it is unlikely that real

degradation mechanisms follow this model precisely, this procedure is so defined as

to provide a conservative estimate of disk life.

In an actual optical recording system, end-of-life is when the ECC can not accurately

correct the errors caused by defects in the media (as well as from all other sources).

A more realistic archival life test would be based on this criteria. However this

requires that the characteristics of the ECC are known. This test method provides a

simpler, system-independent test which is useful to qualify media and to compare the

relative stability of different media.

3.9.1 Archival Life

1) Introduction

Archival Life is the time after a disk is recorded that it can be read with a raw

error rate (RER) not exceeding R^^^, where R^^^ is specified in the appropriate

media specification document.

2) Test Conditions

a) ' The test conditions shall conform to section 2.

b) Measurements shall be made on recordings written at the optimum write power

level as determined with the test method described in section 3.7.9.

c) Measurements shall be made with the setup shown in figure 3.7.11.

d) . All disks used must conform to the specification for initial raw error rate, R.^^.

3) Test Procedure

a) Determine the number of transitions which must be recorded to determine the

RER and be 95% sure the error in the measurement does not exceed 0.1R.

ler This is given by n=384/Rjg^ (see appendix D).

b) Record a 5.0 MHz tone at the radii of 110 mm, 140 mm, and 170 mm. The

number of tracks recorded at each radius shall be such that the total number

of transitions recorded in all three bands is at least the number of transitions

determined in step a, or 5 tracks, whichever is greater.

c) Determine the error rate using the procedure described in section 3.7.11,

46
subsections 3b through 3e. The initial error rate R. is the total number of errors at all three radii divided by the total number of transitions recorded.

Incubation Time in Hours (80T, 50% RH)

Figure 3.9.1. a. Incubation effect on the raw error rate.

Repeat steps b-c on each side of at least 16 disks.

Incubate at least 4 disks at each of the following conditions: T = 40 °C,

60 °C, 80 "C, and 100 °C; 50% relative humidity. The temperature and

humidity must be ramped up from ambient conditions to chamber conditions

and back so that condensation does not occur. Temperature and humidity

ramps shall not exceed 10 °C per hour. Prior to testing, all disks shall be

allowed to equilibrate at the testing environment for 24 hours.

After incubation times of 500, 1000, 2000, and 4000 hours, the disks shall be

retested, and the error rate determined by using the procedure described in section 3.7.11, subsections 3b through 3e.

For each disk surface, a straight line shall be fit to R,. and the error rates

determined after each incubation time. From this fit the time t_, at which the

eol error rate exceeds R^^^ is extrapolated, along with the 90% confidence limits as

47
shown in figure 3.9.1(a). The average <t^oy> of the all surfaces at a given

temperature, weighted by their 90% confidence intervals, is calculated along with

the 90% confidence limit of the average. If any of the disks at any temperature

should show no change in error rate with time, that condition shall eliminated

from further consideration. If less than three temperatures remain after those

with no change in RER are eliminated, then additional temperatures (<100°C>

must be added to the test until 3 valid conditions are obtained.

A plot of log (<teoi>) versus 1/T is formed as in figure 3.9.1 (b) and the data,

weighted by their 90% confidence intervals, is fit to a straight line. From that

line <tgj,i> at 20 °C is extrapolated, along with its 90% confidence limit.

Media is in conformance if the lower 90% confidence limit of <teol> at 20 °C

exceeds the value given in the appropriate media specifications document.

o

10^ L-^j—^—.—I

'—-—I

'—'—I—i'—li- 2.6 2.8 3.0 3.2 3.4 1000/T [K"^]

Figure 3.9.1. b. Extrapolated tp^ value for the archival or shelf life test.

48
3.9.2 Shelf Life

1) IntrcxJuction

Shelf Life is the time after manufacture that a disk can be recorded and read with a raw error rate not exceeding R^^^, where R^^^ is specified the appropriate media

specifications document.

2) Test Conditions

a) The test conditions shall conform to section 2.

b) Measurements shall be made on recordings written at the optimum write power

level as determined with the test method described in section 3.7.9.

c) Measurements shall be made with the setup shown in figure 3.7.11.

d) All disks must conform to the specification for initial raw error rate R.^^.

3) Test Procedure

a) Determine the number of transitions which must be recorded to determine the

RER and be 95% sure the error in the measurement does not exceed 0.1 R.

1 er This is given by (see app. D) n=384/R.g^.

b) Record a 5.0 MHz tone at radii of 110 mm, 140 mm, and 170 mm. The

number of tracks recorded at each radius shall be such that the total number

of transitions recorded in all three bands is at least the number of bits

determined in step a or 5 tracks, whichever is greater.

c) Determine the error rate using the procedure described in section 3.7.11,

subsections 3b through 3e. The initial error rate R. is the total number of errors at all three radii divided by the total number of transitions written.

d) Repeat steps b-c on each side of at least 16 disks.

e) Incubate at least 4 disks at each of the following conditions: T = 40 ° C, 60 ° C,

80 "C, and 100 °C; 50% relative humidity. The temperature and relative

humidity must be ramped up from ambient conditions to chamber conditions

and back so that condensation does not occur. Temperature and humidity

ramps shall not exceed 10 °C per hour. Disks shall be allowed to equilibrate

at the testing environment for 25 hours prior to testing.

49
f) After incubation times of 500, 1000 2000, 4000 hours, repeat steps b and c for

each disk.

g) For each disk surface, a straight line shall be fit to R. and the error rates

determined after each incubation time. From this fit the time t , at which the eol error rate exceeds R is extrapolate, along with the 90% confidence limits as shown in figure 3.9.1(a). The average <tgQ^> of the all surfaces at a given

temperature, weighted by the 90% confidence intervals, is calculated along with

the 90% confidence limit of the average. If any of the disks at any temperature

should show no change in error rate with time, that condition shall be eliminated

from further consideration. If less than three temperatures remain after those

with no change in RER are eliminated, then additional temperatures (<100 °C)

must be added to the test until 3 valid conditions are obtained.

h) A plot of log (<tgQi>) versus 1/T is formed as shown in figure 3.9.1. b and the

data, weighted by their 90% confidence intervals, is fit to a straight line. From

that line <tgQi> at 20 °C is extrapolated, along with its 90% confidence limit.

i). Media is in conformance if the lower 90% confidence limit of <teoi> at 20 °C

exceeds the value given in the appropriate section of the applicable specification

document.

3.9.3 Read/Write/Erase Cycles

The disk shall be tested in accordance with the erase/write/read conditions outlined

in section 2. The parameters listed in table 3.9.3 shall be measure before and after

the specified number of erase/record cycles.

3.9.4 Extended Read

The disk shall be tested in accordance with the erase/write/read conditions outlined

in section 2. The parameters listed in table 3.9.1 shall be tested before and after the

specified number of read cycles.

50
Table 3.9.3. Parameters for the read/write/erase cycles

and extended read tests

Test Section Number

Narrow band 3.7.6

Signal-to-noise Ratio

Crosstalk 3.7.7

Ease of Erasure 3.7.8

Optimum Write Power 3.7.9

Mark Uniformity 3.7.10

Raw Error Rate 3.7.11

Preformat Data Signal 3.8.3

51

Chapter 4

References

[1] ISO 683-13 Heat Treatable Steels, Alloy Steels and Free-cutting Steels - Wrought

Stainless Steels.

[2] EC 950 Safety of Information Technology Equipment Including Electrical

Business Equipment.

[3] NASA MSFC-HDBK-1 674 "Compilation of TVS Data for Nonmetallic Materials."

[4] SP-R-0022 "Vacuum Stability Requirements for Polymeric Materials for Spacecraft

Applications."

[5] ASTM E 595-84 "Test Method for Total Mass Loss and Collected Volatile

Condensable Materials from Outgassing in a Vacuum Environment."

[6] Mil-Std-810E "Environmental Test Methods and Engineering Guidelines."

[7] NASA MSFC-HDBK-1 674 "Compilation of TVS Data for Nonmetallic Materials."

[8] SP-R-0022 "Vacuum Stability Requirements for Polymeric Materials for Spacecraft

Applications."

[9] Proposed American National Standard for Digital Information Interchange, 130

mm Rewritable Optical Disk Cartridge, Unrecorded Optical Disk Cartridge.

X3B1 1/89-096, Part 1.

[10] Proposed American National Standard for Digital Information Interchange, 130

mm Rewritable Optical Disk Cartridge, Recorded Format, Tracking and Servo

Technique. X3B1 1/89-096, Part 2.

53
[11] Proposed American National Standard, Unrecorded Optical Media Unit for Digital

Information Interchange, 356 mm Optical Disk Cartridge - Write Once. X3B1 1/89-

060R1, Part 1.

[12] Proposed American National Standard, Recorded Optical Media Unit for Digital

Information Interchange, 356 mm Optical Disk Cartridge - Write Once. X3B11/89-

060R1 , Part 2.

[1 3] Proposed American National Standard, Test Methods for Media Characteristics

of 130 mm Rewritable Optical Digital Data Disks. X3B11/89-006R1 (X3B11 Test

Methods Project Group document).

[14] Proposed American National Standard, Test Methods for Media Characteristics

of 356 mm Optical Disk Cartridge - Write Once. X3B1 1/TM/89-005R1.

[1 5] Proposed American National Standard, Test Methods for Media Characteristics

of 356 mm Optical Disk Cartridge - Write Once. X3B1 1/89-162.

[1 6] Specification of Track Deviations by a Standard Servo, ISO/IEC JTC1/SC23/WG2

N36.

[17] Substrate Birefringence and Magneto-optic Readout: a Specification Strategy,

A. Marchant, X3B1 1/88-049.

[18] American National Standard for Information Systems - Magnetic Storage Disks

with 14-inch (356 mm) diameter, ANSI X3.1 12-1984.

54
Appendix A

The Optical System Seen by any Beam for

Measuring Write, Read and Erase

Cliaracteristics.

Figure A.1 shows the basic set-up of the optical system. Figure A.1 shows two basic

optical systems. Either one shall be used. In Type A.1 detection, a nearly linearly

polarized beam impinges upon the beam splitter J with the phase retarder I used to

remove ellipticity. In Type A.2 detection, a nearly circularly polarized beam impinges

upon the beam splitter J or the optional half-wave plate H.

a) The linearly polarized beam entering beamsplitter E shall have an extinction ratio

of less than 0.01. ). The extinction ratio of an optical beam is defined as the

ratio of the minimum power over the maximum power observed behind a linear

polarizer in the beam which is rotated over at least 180°.

b1) The alignment of Type A.1 systems involve replacing the optical disk G with a

reflective surface that does not change the polarization. Then, with the retarder

removed, the polarizing beamsplitter J (or optional half-wave plate) shall be

aligned to make the signal of equal to that of The direction of

polarization in this case is called the neutral direction. Then, with the optical

disk and the phase retarder reinserted, a recorded track is read and the phase

retarder adjusted to maximize the differential signal amplitude (channel 2).

b2) The alignment of Type A.2 systems, involve replacing the optical disk with a

reflective surface that does not change the polarization. The quarter-wave

retarder is aligned to balance the and signals. Then, with the optical disk

reinserted, a recorded track is read and the polarizing beam splitter J (or

optional half-wave plate) is adjusted to maximize the differential signal amplitude

(channel 2).

55
c) Channel 1 is the sum of the photodiode signals, and is used for reading

prerecorded marks. Channel 2 is the difference of the photodiode signals, and

is used for reading user-written marks with the magneto-optical effect of Kerr

rotation.

Figure A.1. The optical system seen by any beam for

measuring write, read, and erase characteristics for

Type A.1 detection.

A : laser diode G : optical disk

B : collimator lens H : optional half-wave plate

C : optional shaping prism 1 : Phase retarder

D : beamsplitter (BS) J : polarizing beamsplitter (PBS,

p-s ratio larger than 500)

E : partially polarizing KpKj : photodiodes

beamsplitter (PPBS)

F : objective lens L,.L2 DC-coupled amplifier

Note:

In figure A.1., for Type A.2 detection, H and I are interchanged.

56
Appendix B

Definition of Write Pulse Shape

Figure B.1, shows the write pulse shape. In this figure, RP is the read power, and WP

is the write power.

Figure 8.1 . Definition of write pulse shape.

57

Appendix C

1500 Hz Filter Implementation

Figure C.1 shows an implementation of a 4th-order maximally flat ("Butterworth") filter with a F, of 1500 Hz.

c

039|iF

Hh

.068 \lF

Hh

3.0KQ 3.0KQ

4.1 KO 4. 1 KQ

OljiFj

033JIF

Figure C.I. 1500 Hz filter implementation.

59

Appendix D

Determination of the Number of Transitions

Required for the Raw Error Rate Testing

If a large number n transitions are sampled and n^ are in error then an estimate of

the fraction in error (the RER) is p=njn with a standard deviation of approximately

(p(1-p)/n)'i. Then the 100(1-a)% confidence interval is d = z^^^ * (p(1-p)/n)^, where

the area of the standard normal distribution to the right of z^^^ is a/2.

Solving for n: n = p(1-p) * (z^/j / d)^ .

Typical initial error rates R.^^ are on the order of 10'^, so p(1-p) is approximately

p~ = R. . For a 95% confidence interval, z „ = 1.96.

ler a/2

For the measurement error to be <0.1R,.g^,

then d = O.IRier and n = 384/R.^^.

61

Appendix E

Working Group Participants

Joe Cinelli

GE Aerospace,

Government Communications

Systems Department

Delaware & Cooper Sts., Mail Stop: 13-3-1

Camden, NJ 08102

Jathan Edwards

3M Co.

BIdg. 201-1N-34

St. Paul, MN 55144

Scott A. Gerger

Eastman Kodak Company

Mass Memory Research Labs.

460 Buffalo Rd.

Rochester, NY 14652-3801

Fred Haritatos

Rome Air Development Center

RADC/IRAP

Griffiss AFB, NY 13441

63
Taras Kozak

GE Aerospace

Government Communications

Systems Department

Delaware & Cooper Sts., Mail Stop: 13-3-1

Camden, NJ 08102

Fernando L Podio

NIST

National Computer Systems

Laboratory

BIdg. 225, Room A-61,

Gaithersburg, MD 20899

Pam Rinsland

NASA

Langley Research Center

Hampton, VA

Mail Code: 488

Dr. Thomas A. Shull

NASA

Head, Electronics Branch

Flight Electronic Division

Langley Research Center, Mail Code: 488

Hampton, VA 23665-5225

John Stadler

NASA

Langley Research Center

Hampton, VA 23665

Mail Code: 433

Douglas G. Stinson

Eastman Kodak Co.

Mass Memory R&D

BIdg. 800, Floor 1 KPG

Rochester, NY 14652-3801

64
NIST-114A U.S. DEPARTMENT OF COMMERCE 1. PUBUCATION OR REPORT NUMBER

(REV. 3-90) NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY NIST/SP-500/19]

2. PERFORMING ORQANIZATION REPORT NUMBER

BIBLIOGRAPHIC DATA SHEET 3. PUBUCATION DATE September 1991

4. TITLE AND SUBTITLE Test Methods for Optical Disk Media Characteristics

(for 356 mm Ruggedized Magneto-Optic Media)

j 5. AUTHOR(S)

Fernando L. Podio, editor

PERFORMING ORQANIZATION (IF JOINT OR OTHER THAN NIST, SEE INSTRUCTIONS)

U.S. DEPARTMENT OF COMMERCE

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY

QAITHERSBURQ, MD 20899

7. CONTRACT/QRANT NUMBER

a. TYPE OF REPORT AND PERIOD COVERED

Final

SPONSORING ORQANIZATION NAME AND COMPLETE ADDRESS (STREET, CITY, STATE. ZIP) National Aeronautics and Space Administration

Langley Research Center

Hampton, VA 23665-5225

10. SUPPLEMENTARY NOTES

11. ABSTRACT (A 200-WORD OR LESS FACTUAL SUMMARY OF MOST SIGNIFICANT INFORMATION. IF DOCUMENT INCLUDES A SIGNIFICANT BIBUOGRAPHY OR

UTERATURE SURVEY, MENTION IT HERE.)

Standard test methods for computer storage media characteristics are essential and allow for

conformance verification to media interchange standards. Test methods are also needed to

develop procedures which would allow for repeatability of results among different industry

and U.S. Government sites. The test procedures documented in this publication reflect the

work done by the NIST/NASA Working Group for the Development of Test Methods and Specifications for 356 mm Ruggedized Rewritable Media. The test methods were developed for 356 mm

two-sided laminated glass substrate with a magneto-optic active layer media technology.

These test methods may be used for testing other media types, but in each case their

applicability must be evaluated. Test methods are included for a series of different media

characteristics including; operational, non-operational, and storage environments,

mechanical and physical characteristics, and substrate, recording layer, and preformat

characteristics. Tests for environmental qualification and media lifetimes are also

included. The test methods include testing conditions, testing procedures, a description of

the testing setup, and the required calibration procedures.

12. KEY WORDS (6 T012 ENTRIES; ALPHABETICAL ORDER; CAPITAUZE ONLY PROPER NAMES; AND SEPARATE KEY WORDS BY SEMICOLONS)

erasable media; magneto-optic media; media lifetime; optical disk media; ruggedized optical

media; test methods

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