Abstract: The invention relates to a velocity measurement device of the coherent detection type comprising:an active laser medium (10),an input mirror (M.sub.1) and a first output mirror (M.sub.3) defining, with the laser medium, a first resonant cavity of quality factor Q.sub.max making it possible to emit a laser beam (4),a second output mirror (M.sub.2) defining, with the active laser medium (10) and the input mirror (M.sub.1), a second resonant cavity of quality factor Q.sub.min (<Q.sub.max), making it possible to amplify a measuring signal from a target which has intercepted the laser beam (4) emitted with the aid of the first resonant cavity.

Abstract: The purpose of this invention is a laser speed measurement and range finding device, with coherent detection comprising:a microlaser (10) with continuous emission comprising an active laser medium (10) and a microlaser cavity (16, 18),means (20, 22, 24) for modulating an optical frequency of a beam output by the microlaser,means (28) of outputting a signal depending on:firstly, the Doppler frequency ##EQU1## where .lambda. is the microlaser emission wave length and V is the speed of the target (2) to be detected,secondly, a modulation frequency F.tau. caused by interference in the cavity of the frequency modulated laser oscillation and the signal from a target (2) placed at a distance Z.

Abstract: A microlaser cavity is provided with a solid active medium (2), an entry mirror (4), an exit mirror (60) and a layer of electrically resistive material formed on one of the surfaces of the microcavity. The electrically resistive layer has optical transparency and reflectivity properties adapted to the surface of the microcavity on which the layer is deposited.

Abstract: Autodyne laser velocimeter comprising:a microlaser (10) capable of emitting respectively a first (40) and second (42) beam,pumping means (12) capable of supplying a pumping beam light to the microlaser,optical means (14) capable of directing the first beam (40) at a target (50) and of sending the light re-emitted by the target (50) to the microlaser (10),photoelectric detection means (16) of receiving the second beam and emitting a detection signal corresponding to a modulation in the intensity of the second beam, andmeans (17) of processing the detection signal to determine a characteristic magnitude of a displacement velocity of the target.Application to metrology.