Figure 8-27. Collimator sight-optical system and optical diagram

TM 9-258

b. The principle of the collimator is that a reticle,

through the eyelens as a cross or vertical line of light.

fairly close to the observer, can be optically transferred to

This cross or line of light is the reticle which is placed in

a position infinitely distant from the observer. Parallax

the principal focal plane of the eyelens for the infinity

between the reticle and the target is thereby eliminated.

adjustment.

Since there are only two optical elements, a reticle on a

c. When employed as the sighting device for a

ground glass window and an eyelens, the entire structure

weapon, the mount of the collimator is provided with

can be housed in a compact tube. The eyelens is called

leveling mechanisms and scales which permit the

a collimating lens because it renders rays parallel. It

weapon to be placed at a prescribed elevation with

permits observation of the reticle at infinity or with the

relation to the line of sight established by the collimator.

same eye accommodation as required to view the target.

Sighting is accomplished by looking into the collimator

The ground glass window is covered inside with an

and at the target simultaneously or successively to

opaque coating, excepting an uncoated center cross or

super-impose the cross or line upon the target.

vertical line, through which diffused light can enter to be

8-25. Reflector (Reflex) Sight.

A typical optical

viewed

system of this kind is illustrated in figure 8-28.

8-27