Compact, eye-safe rangefinder weighs only 1.5 pounds

Compact, eye-safe rangefinder weighs only 1.5 pounds

Rick DeMeis

A hand-held eye-safe laser rangefinder has been developed by Sanders (Nashua, NH) for the US Army Night Vision and Electronic System Directorate (Ft. Belvoir, VA). The device uses a Nd:YAG rod side-pumped by two 100-W diode-laser bars. A barium sulfate coating on the rod provides a diffuse reflector for uniform energy deposition within the rod. The passive Q-switched rod output drives an intracavity KTP OPO, producing a 1.57-µm output beam with energies of 1 mJ. The cone-shaped coaxial output/receiver optics of the rangefinder put the InGaAsP photodiode detector at right angles to the beam axis (see photo). The laser output beam is expanded through the 6X telescope producing a 1-mrad full-angle-divergence output beam, matching the field of view of the coaxial receiving optics.

The rangefinder weighs less than 1.5 lb, fits in a 3.75 ¥ 2 ¥ 6-in. carbon-fiber package, and is designed for use with night-vision goggles. The operator projects a spot from an infrared diode laser, which is hard-mounted to and aligned with the rangefinding laser optics, on a target that can be up to 2.5 km away under 7-km visibility conditions. A push of a button produces a range reading within one second to accu racies of ۫ m.