Laser warning receiver

A laser warning receiver is a warning system used as a passive military defence.

Then it alerts the crew and can start various countermeasures, like smoke screen, aerosol screen (e.g. Shtora), active laser self-defence weapon with laser dazzler (LSDW, used on the Chinese Type 99 main battle tank[2]), laser jammer, etc.

Detectors used in LWR are usually based on a semiconductor photodetector array, which is typically cryogenically or thermal-electric cooled.

Sometimes avalanche photodiodes (APD), photoconductivity, photoelectromagnetic, or photodiffusion devices are used even without cooling.

[3] Some devices detect only the main beam of foreign lasers while others detect even scattered rays.