USI Laser Binoculars Rangefinder, 7x50, Commonwealth Armed Forces, 1979
Laser Rangefinder Device, issued to the Commonwealth Armed Forces, in 1979.
On the left plate you will find the following information: COVERT (hidden), 7x50 (magnifications and output lens diameter), USI (probably the encrypted name of the manufacturer) and finally, underneath, an "arrow" to indicate the assignment to the Forces Commonwealth Armies.
On the right plate instead: FOV 130 MILS (Field of View - Field of view 130 Milliradiants), data relating to the internal reticle of the right eyepiece, visible only after the device is turned on. Below we find "RET. DIST. 10MILS", which most likely means "Reticle Distance 10 Milliradiants" and allows this device a very accurate reading of the angular measurement useful for adjusting the shooting angle.
The peculiarity of this telemetry device is that aesthetically it may seem like ordinary binoculars, but it is a concentration of highly advanced electro-telemetry technology.
In fact, on the left side of the eyepiece tube, there is a sort of extractable computer/antenna, which has the function of processing all the information for telemetry (through computers and internal electronic cards), communicating it to the image reflection display, located inside the right eyepiece, superimposed on the reticle.
In the left tube, instead of a magnifying glass, a real "cathode ray tube" with circular lines is used, with the laser sensor inside, connected to the electronic boards, for communication with the display. Therefore, the operator simply needed to direct the device towards the reference point to calculate the exact shooting angle.
Mils: In the military field, the thousandth of a radian (commonly called "thousandth") is a unit of measurement used to determine the deviations, and the related corrections, in artillery shooting.
It is equivalent to a one meter long string of a circle with a radius of one kilometre. For example, to correct a shot that fell 100 meters to the right of a target located 10 km away, you will need to make a correction of 10°° (thousandths) red. The graduated scale observed inside some binoculars is expressed in "Thousandths of Radiant".