Boresight/field Stop Assembly

TM 9-1240-369-34

cavity. At this time, in conjunction flashtube firing, a

assembly contains an amplifying stage. The A-trigger

signal is applied to an OR gate shared with the simulated

"giant" pulse of laser energy is emitted through the

A-trigger signal in the reply gating circuit card assembly

resonant reflector and the recollimating transmitter

located in the power supply unit.

telescope.

(g) Malfunction

3/buffer

logic.

Laser

The

returns are focused by the objective lens into the penta

malfunction 3/buffer logic consists of signal drivers,

prism. This prism folds the laser return into the dichroic

buffers, and the malfunction 3 fault detection circuit. The

beam splitter. A small portion of the laser return is

malfunction 3/buffer logic includes drivers for the A-

trigger and video signals enroute to the interface circuit in

reflected by the beam splitter through a 0.75 milliradian

the power supply unit, receives the test range signal, and

field stop and the recollimating lens. This beam is then

also buffers the reset signal. The malfunction 3 circuit

folded through the 40 A bandpass filter and

consists of a flip-flop which is preset by the fire signal

enhancement prism to the PMT. Most of the visible light

when the laser is fired. When the laser is fired, the flip-

return passes straight through the dichroic beam splitter,

flop receives the A-trigger signal at the K input and the

reticle, and field lens. This beam then goes through the

video signal at the T input. If the A-trigger and video

derotation prism, and is folded through the safety filter

signals do not appear, the Q ouput (O) of the flip-flop

and into the eyepiece of the boresight telescope.

(d) Photomultiplier

chassis.

The

stays low and causes the malf 3 signal to be generated.

The manual reset signal clears the flip-flop so the MALF

photomtultiplier chassis assembly consists of a PMT

indicator and the number "3" on the RANGE (METERS)

assembly and a bias network circuit card assembly. The

indicator goes off.

PMT assembly includes an enhancement prism that, by

(3) Battery power supply unit. The battery power

reflecting part of the light among several surfaces, has

supply unit contains a nickel-cadmium battery supply for

the effect of distributing the light over a large portion of

use as a backup to the prime power source during

the photosensitive surface of the PMT. The PMT bias

emergency conditions. A fully charged battery supply

network provides the necessary PMT dynode biasing

alone can provide the capability of 30 ranging pulses at

and supplies the interface for adding time programmed

70 15F and 10 ranging pulses down to a -20F

gain (tpg) and agc to control the amplification

characteristics of the PMT. Bias voltages as high as

temperature. Depending on the temperature the battery

-1600 V are applied to the PMT.

is subjected to during the charging process, charging to

capacity times will vary. At -25 F the charging circuitry

(e) Video Amplifier.

The video amplifier

amplifies the small signals from the PMT to the level

is deactivated by a temperature sensing transducer

needed to drive the logic circuitry in the data processing

(thermostatic switch) and the battery will not receive a

function. The video amplifier circuit consists of four

charge. This is done to protect the nickel-cadmium cell

linear amplifier stages with feedback circuitry. These are

from damage. To charge the battery whenever this

followed by a threshold circuit and output driver stage.

-25F low temperature condition exists for extended

An agc sensing circuit applies the agc detected signal to

periods of time, the battery power supply unit must be

the age control circuit in the photomultiplier chassis. The

removed and allowed to temperature stabilize above

video signal is applied to the reply gating circuit card

-25F before being charged.

assembly. A portion of the transmitted laser beam is

NOTE

scattered by the scanning prism, through the receiver

The manufacture recommendation as

optics. to the PMT. The PMT amplifies the light and

to the number of complete charge-

applies a signal to the video amplifier. The video

discharge cycles permissible for this

amplifier amplifies the signal to form the A-trigger reply

battery is approximately 100 life

signal. The A-trigger reply signal establishes zero time

cycles. Battery power supply unit

for the range logic.

batteries approaching this limit may

(f) A-trigger assembly.

Data processing

exhibit some signs of deterioration by

requires that an instant before zero-time, when the laser

not holding a full charge for their

transmission pulse is emitted, a signal be generated to

nominal between-charge time.

set the counting circuits and enable various gates. This

is done by the A-trigger signal, which is developed by the

In operation this battery power source takes over

A-trigger sensor assembly and the A-trigger component

when tank voltage falls below the + 18.0 V minimum

assembly. The former consists only of a phototransistor

mounted on the A-trigger sensor assembly and is

positioned directly above the space between the

resonant reflector and the transmitter telescope, where

the phototransistor detects a portion of sidescattered

light from the beam when firing occurs. The latter

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