UDR-TM-86-03

Operation Manual

Contract NAS8-36646

HALL STATION AND CAMERA SYSTEM OPERATION AND MAINTENANCE MANUAL

By:

Andrew J. Piekutowski

Edward A. Strader

University of Dayton Research Institute

Experimental and Applied Mechanics Division

Impact Physics Laboratory

Dayton, Ohio 45469

(NASA-GR-178836)HALL STATION AND CASESAN86-2496 6

SYSTEM- OPEE&1I08; &SD HAIMTEHaHCE BANUAL

(Dayton Univ. , Ohio.) 22 p EC S02/HP A01

CSCL ;14B Onclas

G3/35 43473

April 1986

Prepared For:

George C. Marshall Space Flight Center

Marshall Space Flight Center, Alabama 35812

The University of Day ton
TABLE OF CONTENTS

SECTION PAGE

1 INTRODUCTION 1

2 SYSTEM DESCRIPTION 3

3 OPERATING AND ALIGNMENT PROCEDURES 7

ACCESS PORTS AND WINDOW ASSEMBLIES 7

LIGHT SOURCE ASSEMBLY 9

CAMERA INSTALLATION AND ALIGNMENT 12

MIRROR ASSEMBLY ALIGNMENT 13

4 FILM PROCESSING AND DATA REDUCTION PROCEDURES 16

FILM AND FILM PROCESSING 16

DATA REDUCTION 16

5 FIRING SEQUENCE CONTROLLER 18
LIST OF FIGURES

FIGURE PAGE

1 Diagram of Hall Station and Camera System. 2

2 Hall Station Light Source Wiring Diagram. 4

3 Schematic Diagram of Time Mark Generator. 6

4 Installation of Window Assembly, (a) Engagement

of Brass Guide Pins in Slots (b) Locking

Window in Place. 8

li
SECTION 1

INTRODUCTION

The Hall camera is a diagnostic tool with a relatively long

recording time and a lack of special triggering requirements. It

is used to determine projectile velocity and orientation and to

diagnose sabot functioning. The strip of 16 mm film used to

record passage of the projectile or projectile and sabot also

provides a permanent record of the event.

A high-speed camera, operating in a streak mode, is used to

simultaneously view and photograph objects that pass openings in

a section of the range. Collection of the images (shadowgraphs)

from each opening is accomplished with a system of mirrors that

direct the images into the camera lens. Enhancement of image

definition is achieved by viewing the range through a pair of

slits that are backlit by collimated, high-intensity light

sources. A diagram of a Hall camera system is shown in

Figure 1.

The Hall film record of the event actually provides the time

of flight of the projectile between the slits. A time mark

generator is used to supply extremely short pulses of light at a

known frequency* These pulses of light are used to produce

"timing marks" on the edge of the film. Comparison of the spacing of these marks with the spacing of the projectile images

provides the information necessary to determine the time of

flight of the projectile. Since the slits are installed with a

known separation distance, calculation of the velocity of any

object passing both slits is a simple matter.
HALL VELOCITY STATION

SLIT

FASTAX (FILM)

TUNGSTEN LAMP

COLLIMATING LENS

PROJECTILE

Figure 1. Diagram of Hall Station and Camera System.
SECTION 2

SYSTEM DESCRIPTION .

The Hall station and camera system consists of several major

components. These components are: (1) a section of range

tankage, (2) a high-intensity light source, (3) a mirror system,

(4) a high-speed 16 mm camera modified to operate in a streak

mode, and (5) a time-mark generator. A separate programmable

controller has also been furnished. Use of the controller to

initiate firing of the gun at the appropriate time during the run

of the high-speed camera insures proper seguencing of the camera

and light source functions and facilitates and enhances use of

the Hall camera system.

Both the light source and mirror system are mounted on a

specially fabricated section of range tankage. In addition to

having end flanges for attachment of the unit to adjacent range

sections, the tank also has four, large openings to provide

working access to its interior and two pairs of long, slotted

openings on opposite sides of the tank for viewing the objects

which move down-range. The large openings are equipped with

easily removed or installed aluminum cover plates. The slotted

openings have provisions for the installation and attachment of

guick opening and closing window assemblies. Each of the openings in the tank is made vacuum tight by using 0-ring seals at

the appropriate mating surfaces.

Two high-intensity lamps and appropriate lenses are mounted

in a fan-cooled enclosure which is attached to the bottom of the

range tank. This enclosure also contains several electrical

components for switching and distribution of power to the lamps

(see Figure 2). Approximately 3 kw of power at 240 VAC is required to fully illuminate the lamps.

A second enclosure containing several mirror mounts is

attached to the top of the range tank. The slits through which

the projectile is viewed are attached to the plate forming the

base of this enclosure. The slits and mirrors are used to
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produce and to direct, respectively, the projectile images, so

that a continuous and simultaneous view of all objects passing by

either slit is recorded by the camera.

A Redlake Corporation, Fastax II, Model 46-0007 16-mm, high

speed camera and appropriate lens is used to record the event.

This camera uses 30-m-long (100 ft) reels of film with high-speed

perforations and has a maximum film speed of approximately

55 m/sec, to provide an overall recording time of about 1 second.

The timing light block furnished with this camera has been

modified to accept the high-speed time marker used to place

fiducial marks along the edge of the film. In addition, a BNC

connector has been installed on the rear of the camera to permit

electrical connection to the light emitting diode (LED) in the

timing light block. When in use, the camera should be installed

on the camera mount so that the film plane of the camera is

approximately 4.2 meters away from the range centerline. Refer

to the operating manual furnished with the camera for film loading instructions and camera care and maintenance procedures.

Timing marks or light pulses approximately 100 ns long are

generated at the rate of 10 kHz by the time-mark generator. A

schematic drawing of the generator is presented in Figure 3. The

10 kHz signal is derived by dividing the output of a 1 MHz crystal oscillator by 100. Basic crystal frequency for the

oscillator is +_ 0.015 percent; a maximum aging effect of 10 ppm

results during the first year of operation. Signal output from

the generator is supplied to the camera by a BNC cable which

should not exceed 2 m in length. Since a high driving current is

supplied to the LED, the time mark generator should not be activated for more than a minimum length of time before a test. A

replacement LED has been supplied with the system. Assistance in

replacing the LED is available from personnel of the Impact

Physics Group at the University of Dayton Research Institute.
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SECTION 3

OPERATING AND ALIGNMENT PROCEDURES

The Hall Station and Camera System components were adjusted

and aligned prior to shipment. Consequently, minimal adjustment

of the light source components and mirror systems should be

required after the system has been installed on the range.

ACCESS PORTS AND WINDOW ASSEMBLIES

Removal and installation of the access ports is a straight

forward process. In the event the 1 1/2-inch-long, 3/8-16 socket

head screws which form the "studs" used to secure the access port

covers become damaged or require replacement, merely remove the

damaged screw using a 5/16-inch-Allen wrench from inside the

tank. Remove foreign material from the area of the tank wall

which was in contact with the underside of the bolt head. Prior

to installing a new bolt, place a small bead of a silicone-type

sealant (RTV) around the base of the screw head. When the screw

is tightened, extrusion of the sealant will provide a vacuumtight joint.

Each time a port cover is removed, inspect the O-ring seal

for damage and/or debris contamination. The sealing surface of

the ring should be cleaned and coated with vacuum grease before

returning it to the range. In the event an access port 0 ring

needs to be replaced, use precision Uniform Size Number

451, Buna N, 0 rings.

The window assemblies were designed to eliminate the need to

work in the close space between the tank and the light and mirror

assembly enclosures. The assemblies can be installed and removed

from either side of the tank. Installation of the windows is

made by inserting the brass posts, at the open end of the window

assembly, into the slots in the sides of the block with the
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Removal of the window, assembly is accomplished by reversing the

order of installation.

The 0-ring seal in the top of the block should be cleaned,

inspected, and lightly greased before each use. In the event

replacement is required, Precision Uniform Size Number 254, Buna N,

0 rings should be used. The windows are pieces of ordinary 1/4-

inch thick plate glass, 2 1/8 inches wide by 9 1/2 inches long.

The area of the window over the slotted opening should be

thoroughly cleaned and inspected before each use. Small inclusions of target debris, etc., which embed in the glass usually do

not impair the usefulness of a window. Close inspection of the

16 mm film will indicate when replacement of a window is

required. Replacement of a window is accomplished by removing

the bracket from one end of the glass, loosening the bracket at

the other end of the glass, and removing the old glass. During

installation of the new glass, care should be taken to insure

that the rubber cushions between the bracket and the glass are in

place.

LIGHT SOURCE ASSEMBLY

Refer to Drawing Numbers 93421-21-1 and 93421-21-2 "LIGHT

SOURCE ASSEMBLY" for detail numbers given in the following steps.

WARNING

STEPS 1 THROUGH 5 SHOULD BE PEFORMED WITH THE POWER

OFF AND/OR DISCONNECTED

WARNING

The following steps list procedures which are to be followed when

installating components and preparing the light source assembly

for alignment.

Step 1. Remove the cover on the mirror assembly by removing the four screws on top the cover and lifting

the cover straight up.

Step 2. Remove window assemblies from tank.
Step 3. Remove the light source cover by taking out the

eight screws (Detail 24, four each side) along the

long dimension of the top edges of cover. Only

these eight screws need to be removed. Lift the

cover assembly straight up about 20 mm (3/4 inch)

and slide the cover, with the louvered endplates,

sideways to remove it from the unit.

Step 4. If the high-intensity lamps are not in place,

install Q1500 T-3/CL lamps (Detail 35) in their

holders (Detail 30) by pushing the spring loaded

ceramic sections of the holders back and allowing

the lamp to slip into place. Any smudges or

fingerprints on the lamps should be completely

removed before preceding with the alignment.

Failure to do so will result in the foreign

material being baked onto the lens envelope when

the lamps are turned on.

Step 5. Install the 24 x 169 mm, 44 mm focal length pianocylindrical lenses (Detail 32) in their mounts

(Detail 34) and tighten the spring clips

(Detail 33).

WARNING

WITH THE ILLUMINATOR COVER REMOVED, LINE VOLTAGE IS

EXPOSED TO PERSONNEL. THE VARIABLE TRANSFORMER IN

STEP 6 SHOULD BE ISOLATED FROM THE LINE OR AN APPROPRIATE

GROUND FAULT INTERRUPTER (GFI) SHOULD BE INSTALLED IN THE

CIRCUIT. PERSONNEL PEFORMING THE ALIGNMENT SHOULD BE

PROPERLY TRAINED AND EXHIBIT EXTREME CARE DURING THE

FOLLOWING ALIGNMENT PROCEDURES.

WARNING

Step 6. Connect the large cable from the illuminator to a

variable transformer capable of supplying 5A at

10
120 VAC. Be sure that the green earth ground wire

is properly grounded.

Step 7. The relay (Ry, Fig. 2) in the light source must be

activated to check the alignment of the lenses and

lamps. This may be accomplished by forcing output

0002 of the Programmable Controller "ON". Refer

to Section 6 of Gould Micro 84 Programmable

Control Users Manual. Plug the Programmer into

the Controller. Turn the Memory Protect switch

"OFF". Move the cursor to output 0002 in the

first network. Press SHIFT then press DISABLE

(shifted FORCE). Press FORCE. The relay should

be activated. When the alignment check is complete, press the SHIFT then FORCE key.

Step 8. Turn power "ON" to the variable transformer and

adjust the voltage until the lamps glow. This

will require a transformer output of approximately

30 volts.

The next two steps are followed to check and/or adjust the alignment of the piano-cylindrical lenses.

Step 9. Observe the pattern of light falling on the slits

(located in the mirror assembly). If this pattern

is not centered on and parallel to the slits,

loosen the 1/4-20 bolts (Detail 19) and slide the

lense mounts (Detail 34) from side to side until

the center of the bright area is in the desired

position. Use care during this adjustment to keep

the lenses horizontal and parallel with the

lamps.

Step 10. When the lighted areas are correctly positioned on

the slits, tighten the lens holder mounting

bolts.

11
The landholders were aligned before shipment of the system and

should not require adjustment. However, the following procedures

are to be followed if adjustment should become necessary.

Step 11. Turn power to lamps "OFF".

Step 12. Loosen the 6-32 screws (Detail 2) until the lamp

holders can be moved.

Step 13. Turn power and power transformer "ON". Set voltage to approximately 30 V.

Step 14. Move landholders up or down until the illuminated

area beneath the slits is constant in width. A

slight vertical misalignment of the mounts may be

necessary to achieve the desired light pattern.

Step 15. Tighten the lampholder mounting screws.

This completes assembly and alignment procedures for the

LIGHT SOURCE. The assembly cover should now be returned to the

unit.

CAMERA INSTALLATION AND ALIGNMENT

The camera mount should be bolted to a wall or other rigid

structure located a perpendicular distance of approximately 4.2 m

(14 feet) from the range centerline. The top surface of the

mount should be level and 23.8 cm (9 3/8 in.) above the range

centerline. Attach the camera to the mount.

Install the lens on the camera (refer to the Operating

Instructions for Fastax II - 100 ft. cameras, Section 6, also

Figure 12, page 34). Install the focusing film and position the

horizontal line on the film in the center of the field of view.

To aid in this operation, remove the frame mask (Item 32,

Figure 12) and install the mask with the largest slit. Install

the camera door and boresight.

The focal length of the lens provided with the camera was

chosen so that the shadow (image) of a projectile travelling at

12
4.1 km/sec will travel at the same velocity as the film in the

camera. This requires, for a 50 mm lens, that the film plane of

the camera be located approximately 4.2 meters.from the range

centerline. This distance should be measured along the optical

path of the image through the slit and mirrors of the Hall

station. Small compromises of this distance may be made because

of physical restraints of camera location options. The demagnification (83 to 1) established by this nominal distance has

proven to be adequate for resolution of objects as small as

2.38 mm diameter travelling at velocities of 6 km/sec.

MIRROR ASSEMBLY ALIGNMENT

The following procedures are followed to provide a rough

alignment of the mirrors. In both these procedures and the final

alignment procedures refer to Drawing 93421-20-1 for detail

numbers.

Step 1. Remove the knife edges (Detail 5) forming th slits

at both slit locations. Refer to Steps 6 and 7 in

the LIGHT SOURCE ASSEMBLY Section and dimly illuminate the lamps.

Step 2. Loosen the various mirror mount clamp bolts and

rotate the mirrors until the images of the lamps

are centered on the slit mask in the camera and

viewed through the boresight. During these adjustments, take note of the effect of image motion

provided by movement of each component.

Step 3. Place a short piece of threaded rod in the tank

and position it so that its' long axis is coincident with the range centerline. Adjust the focus

of the camera to obtain the best image of the rod.

Record the distance setting shown on the lens.

Reference to this setting, if the lens should be

accidently moved, will eliminate the need to

remove the pair of slits for refocussing of the

lens. Remove the threaded rod from the tank.

13
Step 4. Replace one of the knife edges at each slit

location. Carefully adjust the distance between

the knife edges to 609.6 mm (24.00 inches + 0.010)

and ensure that they are perpendicular to the

range centerline. Tighten their mounting bolts

and recheck the alignment of the knife edges.

Step 5. Loosely install the other knife edges to form the

slits. Use a piece of 0.25-mm- (0.010 in.) thick

shimstock or a thickness gauge to space the knife

edges and tighten their mounting screws. Remove

the shims.

In the following steps, the final alignment of the Hall station

mirrors is made.

Step 6. Rotate the sprocket in the camera until the line

on the focusing film is exactly centered on the

slit opening. This may require several interactions of inspection through the boresight,

removing the camera door, rotating the sprocket

slightly, re-installing the door, etc.

Step 7. Align the mirrors until the images of the light

passing through the slits are exactly parallel to

the line on the focusing film and lie in the

center of the slit mask. Replace the wide slit

with the finest slit. If the images of the slits

are not fully visible and parallel, further adjustment is necessary. If the images are parallel

to but above or below the slit, the camera mount

must be moved up or down. Be careful to keep the

mount level during this adjustment. If the images

are not parallel, further mirror adjustment is

required. When all alignments are complete,

tighten all bolts loosened during the procedure

and replace the mirror assembly cover. Re-enable

the lamp relay on the controller and connect the

lamps to the 240 VAC circuit.

14
Set the camera lens to f2. A test film should be run after

alignment of the Hall station and mirror system to verify that

the slits are fully illuminated. If the film is fogged by extraneous light, suitable shrouds should be installed to prevent

this light from entering the camera lens.

15
SECTION 4

FILM PROCESSING AND DATA REDUCTION PROCEDURES

FILM AND FILM PROCESSING

Kodak RAR2479 (catalog no. 1714724) is recommended for use

with the Hall Station camera. For best results process this film

for 4 minutes in Kodak D-19 developer at 80°F. Processing time

and/or camera f stop setting may be changed to produce the

desired image density. The entire film can be machine processsed

or a small length, 3 to 4 m (10 to 12 ft) can be processed by

hand.

Since all operations related to running the camera and

firing the gun are controlled by the firing sequence controller,

the very small piece of film, usually less than 25 mm long, which

holds the projectile images is usually located in about the same

position with respect to the end of the film. The position of

the projectile on the film may be moved by using the footage

thumbwheel located at the rear of the camera. Adjustment should

be made only after the "jitter" time of the firing sequence has

been determined, to insure that the image is recorded before the

camera runs out of film.

It is recommended that the position of the data on the film

be determined by hand processing pieces of film 3 to 4 m long,

starting from the end of the roll as it was removed from the

camera. Once the approximate location of the images has been

determined, subsequent films can be processed by discarding the

film after the projectile image and developing only the 3 to 4 m

long piece which contains the projectile images.

DATA REDUCTION

Projectile velocity is determined by measuring the distance

between the images on the film, converting this distance to a

time, and then dividing the distance between the slits [609.6 mm

(24 inches)] by this time. The distance between images can be

16
measured using a Gaertner Scientific or similar travelling microscope with about 10X magnification. The measuring instrument

should be capable of transversing an area 100 mm x 20 mm and have

a resolution of 0.001 mm in the long direction.

The film to be examined is placed under the microscope and

aligned so that the long axis of the film is parallel to the

measurement axis of the reading device. A suitable light source

should be used to illuminate the film so that the projectile

images are clearly visible. Examine both tracks in the film and

select some feature of the projectile which can be readily identified in both film tracks. Use the travelling microscope to

accurately determine the distance, on the film, between these two

points. Next, measure the distance between timing marks for the

purpose of determining the distance the film has travelled during

a given time increment. The selection of timing marks which are

examined should be centered above the portion of film that contains the projectile images. Generally, the distance between 10

successive marks is averaged for the purpose of determining the

movement of the film during 0.1 msec, the time between timing

marks.

The time of flight, t,., of the projectile between the slits

is determined using the following relationship:

tf (in seconds) = *.—_.

dfc x 104

where d = distance between projectile images on film

where d. = average distance between successive timing

marks on film where marks are generated at

4

rate of 10 per second

Computation of projectile velocity is made by dividing the distance between the slits, 0.6096 m (2 ft), by the time of flight,

V

17
SECTION 5

FIRING SEQUENCE CONTROLLER

A Gould Micro 84 Programmable Controller has been provided

to control the operation of the Hall Station and Camera System

and the firing of the gun. The Programmable Controller is a

microcomputer-based device which can be programmed in simple,

relay-ladder logic to perform timing and control functions. The

Users Manual provided with the Micro 84 controller provides

information regarding use and operation of this device.

The Programmable Controller output is used to control closing of several relays which turn on the Hall Station light

source, control operation of the Fastax camera, and complete the

firing circuit of the gun. A status panel has been provided to

indicate the state of the controller sequence.

The sequence is started when the firing relay in the existing firing circuit is closed. An extra contact on this relay is

used to provide a 24VDC signal to the Programmable Controller

(PC) on input 1001. The PC then turns on output 0002 which

activates the start lamp on the status panel and closes relay Kl

which turns on the Hall Illuminator lamps.

Output 0002 also starts a 0.5 second delay (4001). This

delay allows the lamps to come to full brightness. At the end of

the 0.5 second delay, output 0003 supplies 24VDC to K2 which

starts the Fastax Camera. After a predetermined amount of film

(controlled by the setting of the Event FT thumbwheel switch on

the camera) is used by the camera, a 24VDC signal is applied to

input 1002 on the PC. This allows the film to accelerate to the

desired film speed.

When input 1002 is activated, output 0004, which supplied

24VDC to K3, is also activated. This results in the FIRE indicator turning on and the completion of the firing circuit of

the gun.

18
Time delay 4002 is activated by output 0004. After

1 second, outputs 0001 through 0004 are turned off and output

0005 is activated. Output 0005 supplies 24VDC to K4 which stops

the camera. The controller will remain in this condition until

the firing relay contacts open. When the 24VDC is removed from

input 0001, the controller resets to the ready status.

If the firing relay contacts open at any time in the sequence, the controller will reset to the ready status. However,

the camera will continue to run until it is out of film. When

power is first applied to the controller, outputs may activate

briefly. Care must be taken that this action will not cause

damage or hazards.

19