Laser warning device with dividing and filtering of the incident beam

Claim 1

A laser warning device for sector-by-sector surveillance of the air space, said device comprising: a plurality of module sections such that each surveyed sector is coupled through an optical antenna and an optical buffer to a module section, each said module section including: an optical fiber input for receiving a beam of light rays transmitted through the optical fiber; means for dividing the transmitted beam of light rays into at least a first and a second part beam; at least a first and a second optical fiber path for transmitting said first and second part beam respectively; means provided in said first fiber path for filtering the first part beam of light rays to a narrow band beam of light rays; first detecting means for detecting the filtered first part beam and delivering a signal representing the amplitude of the filtered first part beam; second detecting means for detecting the second part beam and for delivering a signal representing the amplitude of the second part beam; and an electronic unit including summing means for summing the signals delivered by said first and second detecting means and threshold means, said electronic unit comparing the summed signal value with a threshold value, the result of the comparison indicating presence or absence of laser light, said electronic unit being coupled to a central evaluating unit.