Thomson-csf

Jean L Meyzonnette

Bertrand Remy

Jean Pierre Huignard

Leon P Robin

Robert Pressiat

Georges Arnaud

The system comprises a laser transmitter/receiver set which transmits laser radiation and processes the radiation received by retro-reflection and a remotely-placed retro-reflecting and modulating set which modulates the laser radiation and sends it back to the receiver. These two sets are mechanically separated, and one can be placed on board an aircraft and the other on the ground, for example. The modulation is done by a frequency-controlled acousto-optical deflector to obtained the operating conditions of diffraction according to Bragg's law. The laser radiation, after crossing the deflector, is sent back by a catadioptric device along its original path. The double passage through the deflector, on the way out and back, produces a shift in the frequency of the laser radiation, the value of the said shift being equal to twice the control frequency of the deflector. A double axis or single axis optical scanning device is added on, for functioning in a wide field.

Identification system using a laser retro-reflecting and modulating set

The device to control the direction of a light beam comprises mainly the following elements substantially aligned in the direction of a laser beam emitted by a source: a low-deflection, controlled deflection device; a holographic multiplexer comprising several recorded zones and giving several possible deflections depending on the direction of the beam that it receives;

Device to control a light beam in a wide angle field and application to

Laser telemetry and Doppler measurement apparatus using pulse compression has a transmitter for providing a periodic pulsed transmission laser wave having a pair of pulses, one pulse being frequency modulated on one side of a main frequency F.sub.E, and the other pulse being frequency modulated on the other side of the main frequency F.sub.E. The transmitter also provides a reference laser wave having a frequency F.sub.L. A photomixer is adapted for superheterodyne reception of the reference laser wave and a return laser signal which has been reflected from a target. The return laser signal has a Doppler shift frequency F.sub.D. The photomixer provides a beat signal having a frequency F.sub.I plus F.sub.D, where F.sub.I is an intermediate frequency. A Doppler aquisition loop transposes the beat signal frequency and provides a transposed signal to compensate for the Doppler shift. The Doppler acquisition loop provides a coarse compensation signal having a frequency near the frequency F.sub.D. Under target tracking conditions, the Doppler acquisition loop then provides an automatic fine compensation signal which compensates for the Doppler difference .DELTA.F.sub.D which exists between the compensation signal frequency and the Doppler shift frequency. Receiving and processing means then receive the transposed signal and provide an output signal indicative of the distance to the tracked target and the Doppler shift frequency of the target.

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Jouy en Josas, France

Jean L Meyzonnette