SUBCOURSE
MM4812
EDITION
9
NIGHT SIGHT (AN/TAS-4A)
NIGHT SIGHT (AN/TAS-4A)
Subcourse Number MM4812
EDITION 9
United States Army Ordnance Missile and Munitions
Center and School
4 Credit Hours
Edition Date: August 1989
SUBCOURSE OVERVIEW
This subcourse is designed to teach you the characteristics, purpose,
and functional operation of the major assemblies and subassemblies of
the AN/TAS-4A night sight.
Contained within this subcourse are
instructions on all assemblies and subassemblies to ensure the
student's understanding of the overall operation of the AN/TAS-4A
night sight.
There are no prerequisites for this subcourse.
This subcourse reflects the doctrine which was current at the time
the subcourse was prepared. In your own work situation, always refer
to the latest publications.
The words "he," "him," "his," and "men," when used in this
publication, represent both the masculine and feminine genders unless
otherwise stated.
TERMINAL LEARNING OBJECTIVE
TASK:
You will identify the characteristics and state the
purpose
of:
major
assemblies,
subassemblies,
and
associated Test Equipment used to support and train
personnel for the AN/TAS 4A night sight.
CONDITIONS:
You will have the subcourse book and will work without
supervision.
STANDARDS:
You will answer 19 of 25 questions
passing score for this subcourse.
i
correctly
for
a
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TABLE OF CONTENTS
Section
Page
Subcourse Overview .............................................
i
Lesson 1: Introduction to the Night Sight (AN/TAS-4A) ..........
1
Practice Exercise ....................................
12
Answer Key and Feedback ..............................
14
Lesson 2: Functional Theory of the AN/TAS-4A ..................
16
Practice Exercise ....................................
46
Answer Key and Feedback ..............................
48
Lesson 3: Night Sight Test Equipment and Maintenance ...........
50
Practice Exercise ....................................
69
Answer Key and Feedback ..............................
71
* * * IMPORTANT NOTICE * * *
THE PASSING SCORE FOR ALL ACCP MATERIAL IS NOW 70%.
PLEASE DISREGARD ALL REFERENCES TO THE 75% REQUIREMENT.
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LESSON ONE
INTRODUCTION TO THE NIGHT SIGHT.(AN/TAS-4A)
Soldier's Manual Task:
093-411-3913
OVERVIEW
TASK DESCRIPTION:
Provide technical assistance to night sight repairers.
LEARNING OBJECTIVE:
ACTIONS:
When you have completed this lesson, you should be able
to identify the purpose, function, and operation of the
Night Sight (AN/TAS-4A).
CONDITIONS:
You will have this subcourse book, and will work without
supervision.
STANDARDS:
You will identify the purpose, function, and operation
of the Night Sight (AN/TAS-4A) in accordance with the
information contained in this subcourse.
REFERENCES:
The material contained in this lesson was derived from
the following publications:
TM
TM
TM
TM
TM
9-5855-450-24.
9-1425-450-12.
9-5855-883-24.
9-5855-884-24.
9-5855-885-24.
INTRODUCTION
The AN/TAS-4A Night Sight is a long-wavelength infrared sensing
system. The night sight detects thermal energy and converts it into
electrical signals that are converted into a visible light image,
therefore allowing the TOW Weapon System to be used day or night in
all weather and all terrain conditions. In this lesson you will be
introduced to the functional operation of the night vision sight,
infrared AN/TAS-4A, its assemblies and test equipment.
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Night Sight (AN/TAS 4A).
The Night Sight (Figure 1-1) is a passive device.
It receives
infrared energy from the target area.
The infrared energy is
converted to electrical signals, and these signals are then converted
to visible light. This visible light is presented to the gunner to
permit real time tracking or observation of a target.
The night sight enables the operator to track targets in darkness,
daylight, and degraded field conditions.
The night sight operates
using a battery power conditioner or vehicle power conditioner, has
narrow field-of-view (NFOV)(12X) and wide field-of-view (WFOV)(4X),
uses a closed cycle cooler to cool infrared (IR) detectors, and has
adjustments to aline the night sight with the optical sight. Listed
in the figure are the external controls and assemblies.
Figure 1-1.
Night Sight.
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Night Sight Controls and Indicators.
Fields of View.
The night sight fields of view (Figure 1-2) are wide field-of-view
(WFOW) and narrow field-of-view (NFOV).
Figure 1-2.
Night Sight Fields of View.
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Night Sight Controls and Indicators (Figures 1-3,4,5).
Figure 1-3.
Night Sight Controls and Indicators.
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Figure 1-4.
Night Sight Controls and Indicators.
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Figure 1-5.
Night Sight Controls and Indicators.
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Night Sight Functional Groups.
The night sight is effectively three functional groups (Figure 1-6):
optical, electronic, and mechanical.
Optical Functions:




Collect infrared energy.
Focus infrared energy on the detectors.
Image visible light.
Display real time scene through the eyepiece.
Electronic Function:





Provide
Provide
Convert
Convert
Process
signals to drive the scanning mechanism.
signals to the detectors.
the incoming IR energy to video signals.
video signals to a visual display.
the video signals.
Mechanical Function:




Switch lens for different fields-of-view.
Secure the night sight to the mounting fixture.
Prevent the escape of stray light from the eyepiece.
Allow target image to be focused.
Figure 1-6.
Night Sight Functional Groups.
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Functional Description.
The night sight (Figure 1-7) receives heat emissions (IR energy) from
a target area, and converts the IR energy to electrical signals.
These signals are processed into video signals (video) and then to
visible light by the light-emitting diode (LED) array which displays
the visible light as a real-time scene for viewing by an observer.

The afocal assembly gathers IR energy and focuses it onto the
scan mirror.

The IR energy from the scan mirror is focused by the IR imager
optics onto the infrared detectors in the detector/Dewar
assembly.

The IR energy is converted by the detectors into video signals.

The video signals are processed by the video electronics and
then converted to visible light by the light emitting diodes in
the emitter assembly.

The visual collimator collimates the visible light onto the scan
mirror.

The objective lens/roof mirror assembly images the visible light
from the scan mirror onto the reticle for viewing through the
eye piece.
Figure 1-7.
Night Sight (AN/TAS-4A).
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Night Sight Equipment.
Equipment
used
with the
night
sight
includes
the
boresight
collimator, battery power conditioner (BPC), and the vehicle power
conditioner (VPC).
Battery Power Conditioner.
The
battery
power
conditioner
(Figure
1-8)
contains
two
nonrechargeable batteries to supply the input power.
The 4.8/16.8
volts direct current (VDC) regulator converts the battery voltage to
regulated 4.8 VDC, and 16.8 VDC, and supplies the voltage to the
night sight junction box.
The battery power conditioner will power
the night sight for about 10 hours when vehicle power is not
available.
Figure 1-8.
Battery Power Conditioner.
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Vehicle Power Conditioner.
The vehicle power conditioner (Figure 1-9) accepts 20 to 40 VDC from
the vehicle and supplies regulated 4.8 and 16.8 VDC through connector
J2 and cable W2 to the night sight junction box.
Figure 1-9.
Vehicle Power Conditioner.
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Boresight Collimator.
The boresight collimator (Figure 1-10) uses electronic, optical, and
mechanical components to produce two parallel beams of energy which
are used to aline the night sight to the optical sight.
There are
two energy sources generated: visible energy and infrared (IR)
energy. Visible energy is produced by an incandescent visible source
lamp directly into visible energy that can be seen by the human eye.
IR energy is obtained when power is applied through lamp and heater
control circuit card (3A1) to the IR source heater on the back of the
reticle.
This causes the reticle to emit IR energy that can be
detected by a night sight, but is not visible to the human eye.
Figure 1-10.
Boresight Collimator.
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LESSON ONE
Practice Exercise
The following items will test your grasp of the material covered in
this lesson. There is only one correct answer for each item.
When you have completed the exercise, check your answers with the
answer key that follows.
If you answer any item incorrectly, study
again that part of the lesson which contains the portion involved.
Situation:
You have been asked by a subordinate
questions pertaining to the Night Sight (AN/TAS-4A).
1.
Infrared active.
Infrared passive.
Telescopic.
Photo.
What wavelength sensing system is the night sight?
A.
B.
C.
D.
4.
Closed cycle.
Open cycle.
Recycle.
Coolant cartridge.
What type of device is the AN/TAS 4A Night Sight?
A.
B.
C.
D.
3.
following
What type of cooler does the night sight use to cool the IR
detectors?
A.
B.
C.
D.
2.
the
Short.
Medium.
Long.
Half.
What is the purpose of the field-of-view selector on the night
sight?
A.
B.
C.
D.
To adjust night sight line-of-sight.
To focus the image.
To adjust azimuth boresight.
To let the gunner choose field-of-view seen in the night
sight.
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5.
Which assembly in the night sight converts IR energy to video
signals?
A.
B.
C.
D.
6.
With the power ON/OFF/STBY switch in the standby position, what
part(s) of the night sight has power applied?
A.
B.
C.
D.
7.
protect the gunner.
filter unwanted light.
protect the eyepiece.
prevent emission of light from the eyepiece.
Mechanical, optical,
Optical, electrical,
Electrical, optical,
Mechanical, optical,
and
and
and
and
infrared.
mechanical.
infrared.
infrared.
What collimates the visible light onto the scan mirror?
A.
B.
C.
D.
10.
To
To
To
To
What are the functional groups of the night sight?
A.
B.
C.
D.
9.
Night sight and cooler.
Night Sight.
Cooler only.
Post amplifier.
What is the purpose of the security shutter in the night sight?
A.
B.
C.
D.
8.
Detectors.
Imager optics.
Roof mirror.
Afocal cover.
Visual collimator.
Boresight.
Objective lense/roof mirror.
Detectors.
What images the visible light from the scan mirror onto the
reticle?
A.
B.
C.
D.
Afocal assembly.
Detectors.
Objective lens/roof mirror assembly.
Visual collimator.
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LESSON ONE
PRACTICE EXERCISE
ANSWER KEY AND FEEDBACK
Item
Correct Answer and Feedback
1.
A. Closed cycle.
Some infrared sights and devices have coolant cartridges to
cool the detectors, but the AN/TAS-4A has a closed cycle
cooler. (Page 2, Para. 2.)
2.
B. Infrared passive.
The AN/TAS-4A Night Sight is a passive infrared system.
(Page 2, Para. 1.)
3.
C. Long.
While there are some infrared devices that have shortwavelength sensing systems, the AN/TAS-4A has a longwavelength system. (Page 1, Introduction)
4.
D. To let the gunner choose field-of-view.
Depending upon terrain conditions and other considerations
the gunner may wish to view the target from narrow or wide
field-of-views. (Page 3, Figure 1-2.)
5.
A. Detectors.
In the night sight the detectors are used to convert IR
energy to video signals. (Page 8, Figure 1-7.)
6.
C. Cooler only.
The cooler is the only part of the night sight to have
power applied with the power ON/OFF/STBY switch in the
standby position. (Page 5, Figure 1-4.)
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7.
D. To prevent emission of light from the eyepiece.
To prevent light escaping from the night sight eyepiece, a
security shutter is installed. (Page 6, Figure 1-5.)
8.
B. Optical, electrical, and mechanical.
The AN/TAS-4A Night Sight is designed with three functional
groups: optical, electrical, and mechanical.
(Page 7,
Para. 1.)
9.
A. Visual collimator.
The visible light is collimated onto the scan mirror by the
visual collimator in the AN/TAS-4A Night Sight.
(Page 8,
Figure 1-7.)
10.
C. Objective lens/roof mirror assembly.
In the AN/TAS-4A Night Sight, the objective lens/roof
mirror assembly images the visible light on the reticle for
viewing. (Page 8, Figure 1-7.)
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LESSON TWO
FUNCTIONAL THEORY OF THE AN/TAS-4A
Soldier's Manual Task:
093-411-3913
OVERVIEW
TASK DESCRIPTION:
Provide technical assistance to night sight repairers.
LEARNING OBJECTIVE:
ACTIONS:
When you have completed this lesson, you should be able
to identify the purpose, function, and operation of the
Night Sight (AN/TAS-4A)
CONDITIONS:
You will have this subcourse book, and will work without
supervision.
STANDARDS:
You will identify the purpose, function, and operation
of the Night Sight (AN/TAS-4A) IAW the information
contained in this subcourse.
REFERENCES:
The material contained in this lesson was derived from
the following publications:
TM 9-5855-450-24
TM 9-5855-247-24
TM 9-5855-450-24
INTRODUCTION
The TOW2 and Dragon Missile Systems provide the soldier with a
reliable method of countering enemy armor on the battlefield.
The
night sight greatly extends the capability of the anti-armor
missiles.
In the previous lesson you were introduced to the Night
Sight AN/TAS-4A and test equipment used with the TOW2 weapon system.
During this lesson you will learn the functional theory of the Night
Sight AN/TAS-4A.
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Facts about the Night Sight.
The AN/TAS-4A Night Sight (Figure 2-1) consists of an afocal
telescope, scanning mirror, detector/Dewar assembly, visible light
optics, and electronic amplification, and control circuits.
When
incorporated into the TOW2 launcher system, the night sight provides
the dual function of a missile-tracking sensor and a gunner's night
sight.
The night sight is an electro-optical system that includes both IR
and visible light optics.
The afocal assembly optics gathers IR
energy and focuses it onto the scan mirror.
Either of two
magnifications may be used.
The IR imager optics (optical imager)
focuses the IR energy from the scan mirror into infrared detectors in
the detector/Dewar.
The detectors convert IR energy to video
signals.
The video signals are processed by the video electronics.
The video is converted to visible light by an emitter assembly (LED
array). The collimator transfers the visible light from the emitter
assembly onto a scan mirror. The objective lens/roof mirror assembly
optics directs this light onto the display reticle for viewing
through the eyepiece optics.
Figure 2-1.
Night Sight Block Diagram.
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Night Sight to Missile Guidance Path.
During the night sight to missile guidance path (Figure 2-2) the
infrared scene is projected on the scan mirror that reflects the
scene to the 60 element detector. Here it is changed into electrical
impulses, called video, and passed to a 60 channel preamplifier
inside the night sight.
The postamplifier assembly contains an
eight-channel selector and a programmable gain postamplifier.
The
eight-channel selector can select 8 of 56 video input signals.
Selection control (i.e. which input line will be monitored) is made
by five-bit selector lines. A missile guidance set software program
controls these five postamp channel select bits.
The eight-channel
postamp provides not only video amplification but also some 16
different selectable gain levels.
The postamplifier assembly outputs (video thermal tracker channels
1-8) are sent to the missile guidance set into a multiplexer. This
multiplexer combines the eight video channels to allow this
information to be changed into digital data by an analog to digital
converter located inside the missile guidance set.
Figure 2-2.
Night Sight to Missile Guidance Path.
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Night Sight Signal Path.
The night sight (Figure 2-3) is a passive device that receives
infrared energy from a target area.
The infrared (IR) energy is
converted to electrical signals and then to visible light.
The
visible light is then displayed as a real time image.
The night
sight does this as follows:

The afocal assembly optics gathers IR energy and focuses it onto
the the scan mirror.

The IR imager optics (optical imager) focuses the IR energy from
the scan mirror onto the infrared detectors in the
detector/Dewar assembly.

The IR energy is converted to video signals by the light
emitting detectors (LEDs). The video signals are processed by
the video electronics and then converted to visible light by the
emitter assembly.

The visual collimator alines the visible light from the emitter
assembly onto the scan mirror.

The objective lens/roof mirror assembly optics images this light
onto the display reticle for viewing through the eyepiece
optics.
Figure 2-3.
Night Sight Signal Path.
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POWER DISTRIBUTION.
Input Power Distribution.
A battery power conditioner or vehicle power conditioner (Figure 2-4)
supplies +4.8 and +16.8 VDC through a junction box to the cooler
assembly and to a consumables monitor/bias regulator in the night
sight.
A switch on the junction box controls power to the cooler
assembly and night sight.
Figure 2-4.
Input Power Distribution.
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Power from the battery power conditioner or vehicle power conditioner
(Figure 2-5) is converted to various DC voltages by the regulator and
DC-DC converter (power supply). The following paragraphs explain the
function distribution of the various DC voltages.
Figure 2-5.
Input Power Distribution.
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Regulator Output Power Distribution.
The consumables monitor/bias regulator (Figure 2-4) supplies +4.8 VDC
through a fuse to the DC-DC converter.
Upon receiving +9.6 VDC and
-9.6 VDC from the DC-DC converter, the consumables monitor/bias
regulator supplies +3 VDC to the video preamplifiers and to the
detectors, and -9.6 VDC to the boresight diode.
Figure 2-6.
Regulator Output Power Distribution.
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DC-DC Converter Output Power Distribution.
The DC-DC converter (Figure 2-7) distributes +4.8, -4.8, +9.6, and
-9.6 VDC to the video postamplifier control drivers, video auxiliary,
and scan and interlace circuit, and +9.6 and -9.6 VDC to the
consumables monitor/bias regulator.
Figure 2-7.
DC-DC Converter Output Power Distribution.
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Afocal Assembly Optics.
The afocal/cover assembly optics (Figure 2-8) gathers IR energy and
focuses it onto the scan mirror.
The afocal/cover assembly optics
has two interchangeable field-of-view (FOV) telescope lenses, with an
objective lens, made of special IR passive material, common to both
fields of view.
The interchangeable lenses provide 4.5X and 1.5X
magnifications of the fields-of-view. The 4.5X Narrow Field-Of-View
(NFOW) lens set consists of two IR lenses. The 1.5X Wide Field-OfView (WFOV) lens is a single IR lens. Both lenses are mounted on the
same frame which is moved longitudinally for focus and laterally,
either vertically or horizontally, for boresight.
The lenses are
mounted so that an approximate 90-degree rotation about a horizontal
axis brings one lens into position and stows the other to accomplish
an FOV change.
Figure 2-8.
Afocal Assembly Optics.
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Afocal Assembly Focus.
The narrow field-of-view (NFOV) and the wide field-of-view (WFOV)
lens assemblies (Figure 2-9) are mounted on the same housing.
The
focus coupling connects the range focus knob to the bevel gear. The
bevel gear meshes with and drives the screw and shaft assembly.
The
screw and shaft assembly is screwed into the focus nut which is
secured to the focus frame. Rotation of the range focus knob causes
the screw and shaft assembly to move the focus frame (with attached
lens assemblies) longitudinally, adjusting the viewed image focus.
Figure 2-9.
Focus Assembly.
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Afocal/Cover Lens Switching (NFOV-WFOV).
Lens switching (Figure 2-10) is accomplished manually by operating
the night sight field-of-view (FOV) handle. Operating the FOV handle
rotates the FOV lens switching housing approximately 90 degrees about
a horizontal axis to bring one lens into operating position and to
stow the other. The external FOV handle is attached directly to the
fork inside the afocal/cover housing.
The fork straddles a pin on
one end of the link assembly.
The link assembly has a pin through
each end and is loaded against the focus frame by a helical spring.
The pin engaged by the fork goes through the link assembly and
attaches to the connecting link.
The other end of the connecting
link is connected to a pin on the lens switching housing. Operating
the FOV handle causes the lens switching housing to rotate
approximately 90 degrees about a horizontal axis to change FOV.
A
linkage in the FOV lens switching mechanism operates a switch mounted
on the basic sight assembly. The switch contacts are closed in WFOV
and open in NFOV.
The position information generated by the switch
is supplied to the TOW guidance circuitry via the night sight
postamplifier assembly.
Figure 2-10.
Lens Switching.
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Afocal/Cover Boresight.
The night sight is boresighted (Figure 2-11) by rotating the AZ
boresight adjustment and EL boresight adjustment knobs.
The AZ
boresight adjustment knob is attached to one end of the boresight
screw and the boresight drive nut is screwed on the other end.
Rotating the lock releases the AZ boresight adjustment knob.
Rotating the AZ boresight adjustment knob clockwise screws the
boresight drive nut out, pushing the boresight frame with afocal
optics lens switching assembly against the spring-loaded yoke
assembly. Rotating the AZ boresight adjustment knob counterclockwise
screws the boresight drive nut in, allowing the spring-loaded yoke
assembly to push the boresight frame horizontally toward the AZ
boresight adjustment knob.
Rotation of the AZ boresight adjustment
knob causes the boresight frame to move left or right about 0.096inch for boresight adjustment.
The EL boresight knob performs an
identical mechanical function in the vertical plane.
Figure 2-11.
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Boresight.
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Scanning Mirror.
The scan mirror (Figure 2-12) oscillates about the scan axis. As the
scan mirror reaches one end of its travel, the scan axis tilts. As
the scan mirror reaches the opposite end of its travel, the scan axis
tilts to its original position. This action creates a 2:1 interlace
scan pattern. The front side of the scan mirror directs incoming IR
energy through the optical imager onto an array of IR detectors. The
back of the mirror receives the visible light output of the LED array
from the visual collimator and reflects it through the objective
lens/roof mirror optics into a visible display optics assembly.
Figure 2-12.
Scanning Mirror.
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Mechanical Scanner.
The mechanical scanner (Figure 2-13) contains the scan and interlace
gimbal (double axis), scan drive tachometer, scan mirror, scan drive
torque motor, interlace flexible pivot bearings, interlace transducer
(2 places), interlace drive solenoid (2 places), and scan return
spring.
The scan mirror oscillates about the scan axis and interlace axis.
These motions are combined so the IR image is moved in a continuous
parallelogram shaped path over detectors to create the 2:1 interlace
pattern.
The front side of the scan mirror is coated for peak reflectivity in
the IR band and directs the incoming IR energy through the imaging
optics onto the array of IR detectors. The back of the scan mirror
is coated for peak reflectivity in the red LED array visual band, and
directs the LED array output through a set of collimating optics into
a visible display. The scan mirror is rotated about the scan axis by
the scan drive torque motor.
The lower torque motor is used as a
scan drive tachometer to provide scan velocity information to the
drive electronics.
Two interlace drive solenoids pivot the gimbal
assembly about the interlace axis during the time the scan return
arms are in contact with the return springs.
A position transducer
is located between the solenoids to provide angular position
information to the interlace drive electronics.
Figure 2-13.
Mechanical Scanner.
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Scan and Interlace Circuitry.
The scan and interlace circuitry (Figure 2-14) consists of two
control loops: the scan loop and the interlace loop. The scan loop
is a rate servo loop using the scan mirror's bottom torque motor B-1
as a tachometer for scan velocity information. The interlace loop is
a position servo loop using two magneto-resistive transducers for
gimbal position information to synchronize shift of the interlace
gimbal solenoid at the end of each scan of the mirror.
Figure 2-14.
Scan and Interlace Loop.
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Scan Loop.
The scan loop (Figure 2-15) is a rate servo loop that causes the scan
mirror to cross the field-of-view at a constant velocity.
The
reference signal for the scan loop is a square wave that is applied
to the comparator. Also applied to the comparator is the scan mirror
velocity signal.
The comparator generates an error signal which is
used to drive and control the speed of torque motor B2.
The scan
drive signal maintains a constant scan mirror velocity across the
field-of-view.
When the scan mirror velocity reaches zero and the
mirror arm fully compresses the return spring, a square wave signal
reverses its polarity, causing the scan drive signal to drive the
mirror back across the field of view at a constant velocity.
Figure 2-15.
31
Scan Loop.
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Interlace Loop.
The interlace loop (Figure 2-16) is a position servo loop.
The
position of the gimbal is determined and positioned by the scan
mirror velocity.
The reference signal is developed by the
differentiator and drive circuit.
The gimbal position signal is
amplified and compared with the reference signal by the driver and
comparator circuit which generates an error signal. The error signal
is used to operate solenoid No. l and is balanced with the signal
from the differentiator to operate solenoid No. 2.
Both solenoids
hold the interlace gimbal in the proper position during the scan
sweeps.
Figure 2-16.
Interlace Loop.
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Visible Light Display Optics.
Optical Imager.
The optical imager (Figure 2-17) focuses IR energy from the scan
mirror onto the IR detector array in the detector/Dewar. The optical
imager has three IR imaging lenses and a folding mirror. IR energy
passes through lens No. 1 and lens No. 2 to the folding mirror. The
folding mirror reflects the IR energy 90 degrees and transmits it
through temperature compensating focus lens No. 3 to the IR detector
array.
Lens No. 3 is mounted on thermal compensating rods that
maintain a constant focal distance with changes in temperature.
Figure 2-17.
Optical Imager.
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Detector/Dewar Assembly.
The Detector/Dewar Assembly (Figure 2-18) is a multi-element detector
array contained in an insulating vacuum.
The insulating vacuum
assists in maintaining the necessary cryogenic temperature required
for efficient operation of the detectors.
The detector/Dewar is
optimized for low heat loss and long vacuum life.
The cooler
assembly coldfinger mechanically slipfits into the detector with a
small gap between the coldfinger and the detector array.
As
independent modules, the detector/Dewar and cooler assembly can be
separated
and
reassembled
for
test
and
replacement.
The
detector/Dewar contains the mercury cadmium telluride (HgCdte) IR
detector array, detector bias resistors, and the interconnecting
leads to the connector pins.
The connector permits external
connection of the detector/Dewar to the video preamplifier modules.
The detector consists of a monolithic 60-active-element linear array
of HgCdte photoconductive detectors and the detector bias resistors
to maintain the proper bias level of each detector.
Figure 2-18.
Detector/Dewar Assembly.
34
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Video Postamplifier.
The video postamplifier control driver (Figure 2-19) provides 60
channels of additional signal amplification, variable gain control,
video gating, and drive current for the LED array. Each of the three
video postamplifier control drivers contains 20 channels of video
amplification.
Since operation of each of the 20 channels is the
same, operation of only one channel is described.
The amplifier
video signal is input to amplifier No. 1. The voltage gain of this
stage is controlled by gain command 1. The polarity control applied
to amplifier No. 1 is fixed by the voltage divider polarity control
circuit. The amplifier video signal from amplifier No. 1 is applied
through the gain balance adjustment circuit to the input of amplifier
No. 2.
Gain command 2, a variable gain control voltage level,
controls the gain of amplifier No. 2. The output from amplifier No.
2 is applied to amplifier No. 3. Amplifier No. 3 provides the final
stage of video signal amplification. The gate and level function is
used to adjust the average brightness during the active scan period
and to shut off the video channel during the scan mirror turnaround
periods to conserve power.
This stage requires two positive
supplies, +9.6 and +4.8 VDC, and a negative supply, -4.8 VDC.
The
current limiter circuit provides current limiting in case a short
circuit occurs across the output of a video channel.
The currentlimiting circuit provides the video drive signals that are applied to
the LED array.
Figure 2-19.
Video Postamplifier.
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Light Emitting Diode Array.
The LED array (Figure 2-20) converts video drive signals to visible
light.
The LED array consists of one multi-element LED array with
integral individual current-normalizing series resistors.
The video
drive signals from the video postamplifier control drivers are
applied to the current-normalizing series resistors, which are
connected to the LEDs and generate normalized current signals in each
LED. The visible light emitted by the LED array varies directly with
the input drive signals.
The LED array contains 180 elements of
gallium arsenide phosphide (GaAsP) diodes arranged in a format
matching the IR detector array with only the center 60 elements used
for video display.
LEDs located outside of the video display
illuminate the boresight diode at the center of scan mirror travel in
order to produce a boresight pulse. Operating current for the three
boresight elements is provided by the DC-DC converter.
The LEDs,
when forward-biased, emit visible red light at a wavelength of 6,600
Angstrom units (A). When the LED array is scanned by the back of the
scan mirror, a visible scene is formed corresponding to the IR scene
scanned simultaneously by the front of the scan mirror.
Scene
brightness depends on the BRT and CRT control settings.
Figure 2-20.
Light Emitting Diode Array.
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Visual Collimator.
Visible light from the LED array (Figure 2-21) is transferred through
the visual collimator into the mechanical scanner.
The visual
collimator contains four fixed lenses. The phase shift lens and scan
mirror are located in the mechanical scanner.
Figure 2-21.
Visual Collimator.
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Objective Lens/Roof Mirror Assembly/Eyepiece.
The objective lens/roof mirror assembly (Figure 2-22) directs the
scan mirror image onto the optical reticle for viewing through the
eyepiece assembly optics.
The objective lens is part of a 2.67X
telescope. The optical elements consist of a double-objective lens.
One element of this lens is moved by a bimetallic annular disc to
effect temperature compensation, a roof mirror which orients the
scene, a field lens to control exit pupil location, an optical
reticle, and a three-element eyepiece lens with diopter adjustment.
Figure 2-22.
Objective Lens/Roof Mirror Assembly.
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Eyepiece Assembly.
Figure 2-23.
Eyepiece Assembly.
The eyepiece assembly (Figure 2-23) contains mechanical shutters and
a diopter focus mechanism.
The shutters prevent light from passing
out of the eyeshield except during operator use.
The diopter focus
mechanism allows reticle focus adjustments.
The shutters are
attached to the inside of the collapsible eyecup.
Pressing the
collapsible eyecup into the eyeshield assembly causes the shutters to
fold away from the viewing path.
Rotating the diopter adjustment
grip moves the eyepiece lens assembly in or out of the eyepiece
housing assembly to focus the reticle.
Figure 2-24.
Eyepiece Assembly.
Eyepiece assembly (part number 13251629)(Figure 2-24) contains a NOT
READY LIGHT which illuminates when the night sight is not ready for
operation.
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Cooler.
The cooler (Figure 2-25) maintains a cryogenic environment for the IR
detector, which is mated to the coldfinger cooling surface.
The
cooler is a Stirling-cycle cryogenic refrigerator capable of
maintaining a temperature of approximately 80 degrees Kelvin (K).
This low temperature is necessary for the proper operation of the
mercury cadmium telluride (HgCdTe) IR detector array.
A motor,
operating on +16.8 VDC, drives the cooler. The motor drives a piston
and regenerator to achieve and maintain the operating temperature.
Figure 2-25.
40
Cooler.
MM4812
Junction Box.
The junction box (Figure 2-26) distributes +4.8 and +16.8 VDC power
via input connector J1 to the night sight, boresight collimator, and
cooler.
ON/OFF/STBY switch S1 controls the power.
When the
ON/OFF/STBY switch S1 is set to on, the junction box supplies +4.8
VDC to the night sight via connector J3 and to the boresight
collimator via connector J4, and supplies a switched +16.8 VDC to the
cooler via connector J2.
The cooler control circuit senses the
detector temperature via J5 and cycles the cooler power on and off
about a referenced voltage to maintain an optimum detector operating
temperature. Setting the ON/OFF/STBY switch S1 to STBY activates the
cooler control circuit and disables the +4.8 VDC to the night sight
and the boresight collimator.
The standby circuit operates the
cooler sufficiently to obtain usable video within 30 seconds after
setting the ON/OFF/STBY switch S1 to ON, without excessive battery
drain during the time when the night sight is not needed.
Figure 2-26.
Junction Box.
41
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Mount Assembly.
The mount assembly (Figure 2-27) secures the night sight to the
optical sight so that the sights are precisely aligned.
The mount
assembly latch handle secures the mount assembly to the cam post on
the optical sight.
The latch handle moves in a horizontal arc of
approximately 55 degrees.
Figure 2-27.
Mount Assembly.
42
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Boresight AN/TAS-4A.
Before boresighting the night sight, you must boresight the optical
sight.
This brings the optical sight's line-of-sight (LOS) into
alinement with the weapon's LOS (aiming point).
The boresight
collimator can then be used to aline the night sight's LOS with the
optical sight's LOS.
Using the boresight collimator, boresight the night sight at the
start of each night sight operation.
These operations include when
the night sight is transferred from one weapon system to another,
when operating sights location changes, when the night sight has been
repaired, and whenever the optical sight is boresighted during a
system self-test.
Figure 2-28 shows how the boresight collimator mates with the AN/TAS4A in preparation for boresighting the night sight to the optical
sight.
Figure 2-28.
Boresight Collimator.
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Reticle Boresight Display Patterns.
The boresight collimator (Figure 2-29) uses electronic, optical, and
mechanical components to produce two parallel beams of energy which
are used to aline the night sight to the optical sight. The pattern
shown is the display you might expect to see while performing the
boresight alinement.
The two circles at the bottom of the reticle
display pattern are monitors:
these monitors are indicator lamps
that warn of shortages. One monitor is for voltage and the other is
for air pressure.
Figure 2-29.
Reticle Boresight Display Patterns.
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Electronic Amplification and Control Circuits.
Video Chain.
The IR energy (Figure 2-30) from the afocal/cover assembly is scanned
by the mechanical scanner.
The scanner provides the scan and
interlace circuit with position and speed information. The IR energy
is reflected from the scan mirror, and is focused on the coolerdetector assembly.
The cooler-detector assembly detects variations
in IR energy and generates low-level video signals that are amplified
by video preamplifiers.
Video from the preamplifiers is applied to
video postamplifier control drivers and to postamplifiers in the
postamplifier assembly.
Output signals from the postamplifiers are
applied to the missile guidance set.
Video from the video
postamplifier control drivers is applied to an LED array.
The LED
array produces visible light which is transmitted to the mechanical
scanner; it is transmitted then to the eyepiece for viewing by the
operator.
Contrast (CTRS) and brightness (BRT) controls adjust the video gain
and level.
The video auxiliary control generates two gain commands
and a video gate and level control signal to the video postamplifier
control drivers.
Figure 2-30.
Video Chain.
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LESSON TWO
Practice Exercise
The following items will test your grasp of the material covered in
this lesson. There is only one correct answer for each item. When
you have completed the exercise, check your answers with the answer
key that follows.
If you answer any item incorrectly, study again
that part of the lesson which contains the portion involved.
Situation:
You have been asked by a subordinate
questions pertaining to the Night Sight (AN/TAS-4A).
1.
aline
aline
aline
aline
the
the
the
the
night sight with the optical sight.
launch tube with the optical sight.
optical sight with the traversing unit.
weapon system with the target.
Afocal/cover.
Mechanical scanner.
Visual collimator.
Objective lens/roof mirror.
Where does the light come from that is applied to the back of
the scan mirror?
A.
B.
C.
D.
4.
To
To
To
To
What assembly contains the scan mirror?
A.
B.
C.
D.
3.
following
What is the purpose of the boresight alinement?
A.
B.
C.
D.
2.
the
Detector/Dewar.
Eyepiece.
LEDs.
IR detectors.
What focuses IR energy from the scan mirror on to the detector
array?
A.
B.
C.
D.
Eyepiece.
Scan mirror.
Detector/Dewar.
Optical imager.
46
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5.
How many lenses are contained in the visual collimator?
A.
B.
C.
D.
6.
What type of loop is the scan loop?
A.
B.
C.
D.
7.
Detector/Dewar.
Scan mirror.
Missile guidance set.
IR detectors.
What directs the scan mirror image on to the optical reticle?
A.
B.
C.
D.
10.
Scan mirror velocity.
IR detectors.
Scan loop.
Detector/Dewar.
Where are the output signals of the postamplifiers applied?
A.
B.
C.
D.
9.
Rate servo.
Rate tachometer.
Open.
Interlace.
What positions the gimbal in the interlace loop?
A.
B.
C.
D.
8.
4
5
6
7
Objective lens/roof mirror assembly.
Video electronics.
Detector/Dewar assembly.
Optical imager.
How many detector elements are contained in the detector/Dewar
assembly?
A.
B.
C.
D.
20
30
40
60
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LESSON TWO
PRACTICE EXERCISE
ANSWER KEY AND FEEDBACK
Item
Correct Answer and Feedback
1.
A. Aline the night sight with the optical sight.
The purpose of the boresight alinement is to aline
night sight with the optical sight. (Page 43, Para 1)
2.
B. Mechanical scanner.
The assembly which contains the scan
mechanical scanner. (Page 29, Para. 1)
3.
the
mirror
is
the
C. LEDs.
The light that is applied to the back of the scan mirror
comes from the LEDs. (Page 17, Para. 2)
4.
D. Optical imager.
The IR energy from the scan mirror is focused on to the
detector array by the optical imager. (Page 19, Para. 3)
5.
A. 4
There are four lenses contained in the visual collimator.
(Page 37, Para. 1)
6.
A. Rate servo.
The scan loop is a rate servo loop.
7.
(Page 31, Para. 1)
A. Scan mirror velocity.
The scan mirror velocity positions
interlace loop. (Page 32, Para 1)
8.
the
gimbal
in
the
C. Missile guidance set.
The output signals from the postamplifiers are sent to the
missile guidance set. (Page 45, Para 1)
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MM4812
9.
A. Objective lens/roof mirror assembly.
The scan mirror image is directed on to the optical reticle
by the objective lens/roof mirror. (Page 19, Para 6)
10.
D. 60
The detector/Dewar assembly contains 60 detector elements.
(Page 34, Para 1)
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LESSON THREE
NIGHT SIGHT TEST EQUIPMENT AND MAINTENANCE
Soldier's Manual Task:
093-411-3913
OVERVIEW
TASK DESCRIPTION:
Provide technical assistance to night sight repairers.
LEARNING OBJECTIVE:
ACTIONS:
When you have completed this lesson, you should be able to
identify the purpose, function, and operation of the Night
Sight test equipment
CONDITIONS:
You will have this subcourse book, and will work without
supervision.
STANDARDS:
You will identify the purpose, function, and operation of
the Night Sight (AN/TAM-3A) test equipment in accordance
with the information contained in this subcourse.
REFERENCES:
The material contained in this lesson was derived from the
following publications:
TM 9-5855-255-14.
TM 9-4935-455-14.
INTRODUCTION
To perform the necessary maintenance on the night sight, specific
test equipment is required.
Only limited repairs, checks or
alinements can be performed on the night sight without the test set.
In this lesson, you will learn the components and functions of the
night sight test equipment.
50
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Night Sight Maintenance Facility.
To test and support the night sight, the night sight maintenance
facility (NSMF)(Figure 3-1) is required. The NSMF is listed as shop
equipment guided missile An/TAM 6 and is used at the general support
area. The NSMF shelter can be mounted on a 2 1/2 ton truck and moved
as required. The AN/TAM 6 contains the following equipment:




Test set, night vision AN/TAM 3A.
Boresight collimator test set (BCTS).
Amplifier test set AN/TAM 5.
Purging kit.
Figure 3-1.
Night Sight Maintenance Facility (NSMF).
51
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AN/TAM-3A.
The AN/TAM-3A test set (Figure 3-2) is used to support the AN/TAS-4A
night sight.
This test set includes two special tool containers in
the night sight maintenance facility (NSMF).
Each provides storage
for the unit under test (UUT) mount assembly, and interface needed to
test and repair the night sight.
A third container is the thermal
sight collimator. The closed cycle cooler test set is stored inside
the thermal sight collimator container.
Figure 3-2.
52
AN/TAM-3A.
MM4812
Amplifier Test Set (AN/TAM 5).
The Amplifier Test Set is used to isolate a fault in the
postamplifier assembly to a single replaceable subassembly, to gainbalance the Video buffers, and to aline the Night Sight eyepiece
reticle assembly. When testing the night vision sight, use the test
set in conjunction with the night vision test set AN/TAM-3A.
Major
controls of the amplifier test set are video channel select, gain
select, and signal select.
The mode of operation is determined by
the manual/auto, stop/start, and reset switches. The amplifier test
set contains one circuit card and a power module. A part of the test
set is the boresight alinement fixture.
The boresight alinement
fixture is used to perform alinement of the night sight eyepiece
reticle assembly.
Figure 3-3.
Amplifier Test Set and Boresight Alinement Fixture.
53
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Closed Cycle Cooler Test Set.
The closed cycle cooler test set contains a vehicle power conditioner
(VPC), a BPC/VPC load box, and the cables necessary to check the
operation of the closed cycle cooler.
Stored in the collimator
container, the test set includes:

Cooler Extension Cable 7W8: Connects BPC or VPC directly to the
cooler input power cable and the night sight power input when
the junction box is removed.

BPC/VPC Load Assembly: Provides
testing the 4.8 and 16.8 VDC.

Vehicle Power Conditioner: Converts 20 to 40 VDC from a vehicle
to 4.8 and 16.8 VDC for the closed cycle cooler in the night
sight.

BPC Test Cable 7W7:

Night Sight Power Cable 8W1:
sight junction box.
Figure 3-4.
3.16 and
13.7 ohm
loads
for
Connects BPC to bench power supply.
Connects BPC or VPC to the night
Closed Cycle Cooler Test Set.
54
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Purging Equipment.
The purging equipment consists of a purging kit and a nitrogen
bottle.
The purging kit is used along with the nitrogen bottle to
fill the night sight with dry nitrogen.
The kit has a regulator,
valve, hose and adapter.
Figure 3-5.
Purging Equipment.
55
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Thermal Sight Collimator.
The thermal sight collimator (Figure 3-6) is used to check out and
aline the night sight.
The thermal sight collimator is an electrooptical system that includes both IR and visible light optics.
Different paths are taken through the unit depending on the source of
energy.
In the IR energy path, the IR energy is emitted from the
heated reticle through the hole in the folding mirror.
It is
reflected by the collimating mirror to the folding mirror and then
goes through the IR window to the night sight.
The thermal sight collimator contains:



Temperature controller assembly.
Shroud.
Temperature controller assembly power cable Wl.
The thermal sight collimator has three functions:



Electronic.
Mechanical.
Optical.
Figure 3-6.
Thermal Sight Collimator.
56
MM4812
Temperature Controller Assembly.
Electronic Function (Figure 3-7).
The temperature controller assembly and target source assembly
provide a control temperature differential between target source and
ambient temperature.
Temperature differential (4.5 degrees C) is
maintained by sensing the target source ambient temperatures and then
regulating the current through a heater.
Input power of 115 VAC and 0.5 ampere is applied through circuit
breaker CB1. Transformer T1 steps the voltage down to 24 VAC. The
24 VAC is fullwave rectified by the temperature comparator to produce
24 VDC, causing the POWER ON indicator DS2 to illuminate.
Temperature sensor A2A1 monitors the temperature of the target, and
temperature sensor A2A2 monitors the ambient temperature.
The
voltage differential of the sensors is applied to the temperature
comparator A1A1, which supplies heater current to A2R1.
The
temperature comparator provides heater A2A1 current as required to
maintain a 4.5 degree C temperature differential.
Figure 3-7.
Electronic Function.
57
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Electronic Circuit Function.
The electronic circuits of the boresight collimator are the lamp
circuit and the reticle heater control circuit.
In the reticle
heater control circuit, a reference voltage is supplied to the
differential amplifier and to the constant current source.
A
constant current from the constant current source is supplied to the
background temperature sensor and to the reticle temperature sensor,
which is located on the back of the reticle.
The output of the
reticle temperature sensor is applied through an amplitude control to
the comparator, where it is compared with the output of the
background temperature sensor.
The output from the comparator and
feedback from the heater driver control the differential amplifier.
The differential amplifier provides the input to the heater driver.
The output of the heater driver powers the IR source heater, which
raises the temperature differential between the source and the
reticle (target) to produce the IR pattern.
Figure 3-8.
Electronic Circuit Function.
58
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Mechanical Function.
UUT Mount Assembly.
The UUT mount assembly consists of a platform that is movable in
azimuth and in elevation. Angular limits of travel are 4 degrees in
both planes.
Azimuth movement is accomplished with a platform that is pivoted
about a point located near the front of the mount.
The rear of the
platform rides on a rubber-ringed wheel that is rotated by turning
the azimuth adjustment control.
Elevation movement is accomplished with a platform that is hinged and
pivoted at its front edge.
As the elevation adjustment control is
rotated, a wedge moves forward or backward against a cam that is
attached to the platform.
Movement of the wedge against the cam
causes the platform to move about its pivot point.
Stablization of the UUT mount assembly is provided by a brace that
folds out from the base plate.
Figure 3-9.
UUT Mount Assembly.
59
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Temperature Controller Assembly.
The mechanical function of the thermal sight collimator consists of
the target select knob on the temperature controller assembly to
select one of the six target plates for viewing by the thermal sight
under test.
A detent is used to lock the target in position.
The
shroud protects the temperature controller assembly from temperature
variations and air currents which could affect target temperature.
Figure 3-10.
Temperature Controller Assembly.
60
MM4812
Optical Function.
The thermal collimator is used to provide a 58-inch focal length for
the night sight testing and alinement.
The thermal sight collimator radiates infrared energy from the
temperature controller assembly.
The energy is reflected from a
collimating mirror to present a collimated beam of infrared rays.
These rays can be viewed with the night sight being tested.
The target source is placed near the focal point of the collimating
mirror.
The target source provides images of target patterns to a
night sight.
The focal length of the collimating mirror is 58
inches. The infrared energy from the target source is reflected from
a folding mirror to the collimating mirror.
The folding mirror is
used to achieve the 58-inch focal length in a shorter actual length.
Each beam of visible light passes through a visible light window
where it may be viewed as a visible image.
Figure 3-11.
Optical Function.
61
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BPC/VPC Load Box Assembly.
The BPC/VPC load box (Figures 3-12, 13) is a load for testing the
Battery Power Conditioner (BPC) or the Vehicle Power Conditioner
(VPC).
The power conditioner output cable connects to the load
assembly connector J1.
Load assembly test jacks J2 and J3 are used
to measure +4.8 VDC. The jacks are connected across an internal 3.16
ohm load resistor.
Load assembly test jacks J4 and J5 are used to
measure +16.8 VDC.
The jacks are connected across an internal 13.7
ohm load resistor.
Figure 3-12.
BPV/VPC Load Box Assembly.
Figure 3-13.
BPC/VPC Schematic
62
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VPC Load Box Assembly.
The VPC load box assembly (Figures 3-14,15) provides a load for
testing a vehicle power conditioner.
A BNC connector connects the
vehicle power conditioner to a 3.16 ohm load resistor within the load
assembly. The load assembly panel has two test terminals for voltage
measurements.
Figure 3-14.
VPC Load Box Assembly.
Figure 3-15.
VPC Schematic.
63
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AN/TAM-3A Box 1.
The AN/TAM-3A Box 1 Special tools container (Figure 3-16), a two
piece unit provides storage for the following items:
Figure 3-16.
AN/TAM-3A Box 1.
64
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AN/TAM-3A Box 2.
The AN/TAM-3A electronic test equipment (Figure 3-17) contains a
digital multimeter (DM 501), oscilloscope (SC 502), mainframe (DM
503), and a power supply (6284A).
The Tektronix DM 501 digital multimeter is a small lightweight meter
that can read out voltage, current, and ohms. The meter will show a
plus or minus sign next to the readout, and will place the decimal
point in the correct position. The meter is protected from overloads
using shunt resistors.
The Hewlett Packard 6284A power supply has an output voltage of 0 to
20 VDC and an output current of 0 to 3 amps DC. It operates from an
input of 115 VAC, and a frequency of between 48 and 440 Hz.
The
Tektronix SC 502 is a two channel oscilloscope allowing two signals
to be viewed at the same time. It operates from an input of 115 VAC
supplied by the mainframe. The mainframe houses both the multimeter
and oscilloscope.
Figure 3-17.
AN/TAM-3A Box 2.
65
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Night Sight Maintenance Concept.
Like other systems and equipment, the night sight has a three level
concept for maintenance.
Those levels are: Unit, intermediate
(DS/GS), and depot.
The following paragraphs will explain the
different levels, and what services each level performs.
Unit Maintenance.
Unit maintenance is the maintenance performed on a piece of equipment
by the using unit, and includes:





Doing checks and operator adjustments.
Spot painting.
General cleaning of equipment.
Handling
boresight adjustment procedures (Aline night sight
with the optical sight).
Notifying direct support to perform the 180 day verification
check.
Figure 3-18.
Night Sight.
66
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Intermediate Maintenance (DS/GS).
The intermediate maintenance units will provide checkout and fault
isolation for the night sight. Maintenance support equipment for the
night sight is the AN/TAM-3A.
Intermediate maintenance operations
include:

Providing technical supply system.

Providing Contact Support Teams (CSS).

Providing and maintaining an Operational Readiness Float.

Evacuating unserviceable PCBs and subassemblies
intermediate GS/depot level repair facilities.
Figure 3-19.
directly
to
DS/GS Maintenance.
67
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Depot Maintenance.
Depot maintenance facility for the night sight is the Anniston Army
Depot located in Anniston, Alabama.
This maintenance facility
repairs the overflow from intermediate GS units, and also repairs
those pieces of equipment that the intermediate GS is not capable of
repairing. Depot maintenance operations include:

Providing
units.

Routing repaired items into the supply system.

Performing diagnosis and repair of SRUs.

Providing repair parts supply for the theater.
the
interface
Figure 3-20.
between
depot
and
DS/GS
maintenance
Depot Maintenance.
68
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LESSON THREE
Practice Exercise
The following items will test your grasp of the material covered in
this lesson. There is only one correct answer for each item. When
you have completed the exercise, check your answers with the answer
key that follows.
If you answer any item incorrectly, study again
that part of the lesson which contains the portion involved.
Situation:
You have been asked by a subordinate the
questions pertaining to the Night Sight Test Equipment.
1.
What is the designator of the digital multimeter that is part of
the AN/TAM-3A?
A. DM
B. SC
C. TM
D. SC
2.
following
501.
502.
503.
504.
What is the
Collimator?
output
of
transformer
T1
in
the
Boresight
A. 24 VAC.
B. 24 VDC.
C. 115 VAC.
D. 220 VAC.
3.
Which component maintains constant current through the ambient
temperature source?
A. A2A1.
B. A2R1.
C. AlA1.
D. A2A2.
4.
What is the load applied to the 16.8 VDC output of the BPC/VPC
for testing?
A. 3.16
B. 13.7
C. 34.9
D. 54.9
ohm.
ohm.
ohm.
ohm.
69
MM4812
5.
What are the angular limits of the UUT Mount Assembly?
A. +
B. +
C. +
D. +
6.
or
or
or
or
2
3
4
5
degrees.
degrees.
degrees.
degrees.
What is the focal length of the thermal collimator?
A. 36
B. 48
C. 52
D. 58
7.
-
inches.
inches.
inches.
inches.
Where is the Closed Cycle Cooler Test Set stored?
A. AN/TAM-3A container.
B. AN/TAM-5 container.
C. Collimator container.
D. AN/TAS-4A container.
8.
How many target plates can be selected by the
controller assembly in the boresight collimator?
temperature
A. 2
B. 3
C. 4
D. 6
9.
What temperature differential is maintained
between the target
source and ambient sensors in the boresight collimator?
A. 3.6
B. 3.8
C. 4.5
D. 4.8
10.
degrees
degrees
degrees
degrees
C.
C.
C.
C.
What item of test equipment is used to aline the night sight
eyepiece reticle?
A. Boresight alinement fixture.
B. Boresight collimator.
C. Closed cycle cooler test set.
D. BPC/VPC load box assembly.
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LESSON THREE
PRACTICE EXERCISE
ANSWER KEY AND FEEDBACK
Item
Correct Answer and Feedback
1.
A. DM 501.
The digital multimeter that is part of the AN/TAM-3A test
set is DM 501. (Page 65, Para 1)
2.
A. 24 VAC.
The output of transformer T1 in the boresight collimator is
24 VAC. (Page 57, Para. 2)
3.
C. AlAl.
The component that maintains constant current through the
ambient temperature source is AlAl. (Page 57, Para. 3)
4.
B. 13.7 ohm.
The load that is applied to the 16.8 VDC output of the VPC
or BPC is 13.7 ohms. (Page 62, Para. 1)
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MM4812
5.
C. + or - 4 degrees.
The angular limits of the UUT mount assembly is + or - 4
degrees. (Page 59, Para. 1)
6.
D. 58 inches.
The focal length of the thermal collimator is 58 inches.
(Page 61, Para. 1)
7.
C. Collimator container.
The closed cycle cooler test set is
collimator container. (Page 54, Para 1)
8.
stored
in
the
D. 6
The target select knob on the temperature controller
assembly can select one of six target plates for viewing.
(Page 60, Para 1)
9.
C. 4.5 degrees C.
A temperature differential of 4.5 degrees C is maintained
between the target source and ambient. (Page 57, Para 1)
10.
A. Boresight alinement fixture.
The boresight alinement fixture is used to perform
alinement of the night sight eyepiece reticle assembly.
(Page 53, Para 1)
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MM4812