Thomson-csf

Societe Anonyme De Telecommunications

Bertrand Remy

Jean L Meyzonnette

Leon P Robin

Robert Pressiat

Jacques J Lonnoy

Georges Arnaud

Guy Timossi

Jacques-Henri Rothenburg

Denis Levaillant

Jean L Meyzonnetie

The system comprises a focusing optics in the focal plane of which a linear array of photodetectors is disposed. A double prism located opposite to said photodetectors with respect to said focusing optics, is servo controlled in rotation relative to a support about its longitudinal axis perpendicular to the axis of said optics, said support being itself servo controlled in rotation about said optical axis in order to scan a space of about 2 .pi. steradians. A derotating prism aligned with said optical axis rotates about said optical axis at a speed half of that of said double prism, in order to hold the image of the target in a single direction in said focal plane, whatever the rotations of said support.

Target acquisition optoelectronic system with a very wide field

Laser active imaging system allowing in particular to use a wide field by means of a detecting device including a linear array of N juxtaposed photodetector elements oriented along the direction of scanning and associated with a focusing lens. The receiver includes a circuitry receiving the N detected channels and is equipped with compensation circuits for the time shift exhibited by the video signals as a function of the distance so as to bring the illuminated objects back to their angular location for the display of the observed field. The processing circuits include circuits for measuring the amplitude and the Doppler shift and for identification of the distance through the rank of the detection channel.

Laser imaging system with a linear detector array

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

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.

Laser telemetry and Doppler measurement system with pulse compression

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Cachan, France

Bertrand Remy