Abstract: The diffraction grating principle is used to deflect an infrared beam in a series of discrete predetermined directions. A periodic control voltage having a staircase waveform with N steps is applied across a liquid crystal layer to create local variations of refractive index therein, thereby setting up an infrared diffraction grating of adjustable pitch.

Abstract: The invention utilizes a laser cavity between two spherical mirrors, between which an oscillation wave propagates. An amplifying medium and an interaction medium are located on the path of the oscillation wave. A signal wave interferes with the oscillation wave in the interaction medium. A modulator of said wave makes it possible to initialize the process to obtain an output beam emerging in the desired direction.

Abstract: A camera in accordance with the invention comprises a coherent light source from which is formed an object illuminating beam and a pumping radiation beam, and an interaction medium for receiving the pumping wave and the imaged wave reflected from the illuminated object. This medium diffracts in real time a replica of the imaged wave which is reflected from the object.

Abstract: An optical observation system in accordance with the invention comprises illumination means by scanning the object and means for detecting the radiation diffracted by the object. It also comprises an interaction medium in which the wave emerging from the object interferes with a pumping wave in order to induce in it a system of layers diffracting in real time a replica of the object wave propagating in the direction of said wave and a complex conjugate wave propagating in the opposite direction. These waves, which are isomorphic of the object wave help to improve the detection of the object.

Abstract: The rotary-joint device has the design function of maintaining accurate positioning of the ends of optical fiber conductors during relative rotation of external bodies to which the joint is coupled. The device comprises a male ferrule and a female ferrule so arranged as to form a shaft rotatably mounted within a sleeve with a close but compliant fit, an abutment device for limiting the axial displacement of the sleeve, means for centering the ends of the conductors, and means for securing said ferrules to external connector bodies so as to form a rigid coupling and a semi-rigid coupling respectively.

Abstract: A light retro-reflective responser and data modulator arrangement which, in particular, allows expected incident radiation to be reflected back with no contour field within the operating field and which enables an optical modulator of very small size to be used. It comprises a retro-reflective system formed by an optical objective and in the corresponding focal zone, a lens, an electronically controlled optical modulator, and a reflective mirror, the two latter items being produced as layers deposited on at least one face of the lens and preferably on the plane face of a plano-convex lens.