Right Optical System

TM 9-258

(3) Right Optical System. The right optical

point, the light combines with the reflected light from the

system consists of an end housing assembly, a main

left field of view and proceeds to the single eyepiece.

The right

sighting system, and a collimating system. A target

image picked up at the end housing assembly is

collimating system performs the same function as the left

transmitted into the main sighting system. A coincidence

collimating system in (2) (d) above.

1. The right coincidence reticle (14) is

reticle (14), projected from the collimating system, is also

projected in this main sighting system. An auxiliary

illuminated and projected into the collimator lens (39).

gunlaying reticle is located in this system, and, if

2. The collimator lens (39) gathers the

illuminated, is projected into the main sighting system.

diverging light from the reticle assembly and directs it

These images are transmitted to the eyepiece which is

with the coincidence reticle image into the porro reflector

common to the left and right optical systems.

assembly (30 and 31).

(a) End housing assembly. The end housing

3. The ICS corrections wedge mount assembly

assembly for the right optical system is identical to that

for the right collimating system is similar to the collimator

for the left optical system in (2) (a) above.

assembly for the left collimating system, except that the

(b) Right main sighting system. The right main

ICS wedge (36) for deflection correction can be rotated

sighting system carries the target image from the right

by the ICS knob. This moves the coincidence reticle (14)

end housing assembly to the eyepiece. The right main

in a horizontal plane.

sighting system is housed in the right main housing

(d) Auxiliary boresight (gunlaying) reticle

casting.

system.

The auxiliary boresight (gunlaying) reticle

1. The range finder end window (25) is a plano

system can be used for auxiliary sighting and range

plate and seals the right sighting system against dirt and

estimation if the left optical system becomes inoperative.

moisture.

It can also be used to check range finder alinement by

2. The filter (26) increases contrast between

checking its coincidence with the left main boresight

the target image and the illuminated coincidence reticle

reticle (16). The system consists of two assemblies: an

(14). A matched filter (5) for the left main sighting

auxiliary boresight (gunlaying) reticle bracket assembly

system is engaged simultaneously with the right filter by

and an auxiliary boresight (gunlaying) lens assembly.

a control lever on the right main housing casting.

1. The auxiliary boresight (gunlaying) reticle

3. The compensator lenses (27 and 28)

bracket assembly has a reticle lamp (53), a dark field

provide angular deviation for ranging.

cemented auxiliary boresight (gunlaying) reticle (55), and

4. The porro reflector assembly (30 and 31) in

reticle mirror (56) to reflect the reticle image into the

the right main sighting system is similar to that of the left

system.

2. The auxiliary boresight reticle lens assembly

main sighting system, except for the halving adjustment.

The halving adjustment tilts the porro reflector to change

has two reticle lenses (35 and 37). Both reticle lenses

the elevation of the coincident reticle (14) in relation to

are adjustable longitudinally along the optical axis for

the target image.

proper focusing of the reticle image at the eyepiece field

5. The 90-degree prism (32) bends the target

stop.

In addition, reticle lens (37) is adjustable

image into the objective lens (33).

transversely by means of the auxiliary boresight knobs to

6. The objective lens (33) converges the target

provide horizontal and vertical movement of the reticle in

image and the coincidence reticle image to a focal point

the field of the right optical system.

3. The porro prism (34) turns the light rays 180

at the eyepiece field stop (42) through the beam-splitter,

the, right ocular,, and the combining prisms.

degrees into the beam-splitter prism (41).

7. The beam-splitter prism (41) reflects the

(4) Reticle Patterns.

(a) General. Four reticle patterns are used in

image 90 degrees into the right ocular prism (40) and

superimposes the image of the auxiliary boresight reticle

the range finder. There is one pattern for gunlaying (A,

(55) on the target image. It also dissipates part of the

fig 8-26), one for auxiliary gunlaying (B, fig 8-26), and

light in the right main sighting system to balance the

two-coincidence reticle patterns (C, fig 8-26). The

transmitted light with that in the left main sighting system.

coincidence reticles are provided to aline the optical

8. The right ocular prism (40) reflects the target

systems (left and right) to each other. An auxiliary reticle

image into the right angle prism component of the

is projected into the right optical system in the event of

combining

prism

(45).

this

damage to the left optical system.

8-24