Abstract: The present invention relates to a method and to a device for automatically correcting, in a single application, positioning errors of optical elements of an optical system, with respect to the optical axis of said system. According to the invention, said device (1) has means (A1, A2, Am) for taking measurements representative of image shifts with respect to said optical axis, a calculation unit (UC) for determining on the basis of said measurements, values representative of positioning errors of optical elements, and means (C1, C2, Cn) for automatically modifying the positioning of said optical elements on the basis of these values.

Abstract: A device for determining the phase errors of electromagnetic waves (OE) which are generated by a light source and transmitted by an optical instrument includes a reception system (SM) having at least one measurement plane (PM, PM3, PM4) provided with a plurality of measurement zones (ZM) which can measure the intensity of the received light and a collimation means (L1) for sending to the measurement plane (PM, PM3, PM4) the electromagnetic waves (OE) transmitted by the optical instrument.

Abstract: A device for guiding a civil engineering/earthmoving machine using laser beams having a laser emitter and two laser receivers each mounted on a displacement unit mobile with two degrees of freedom. Two receiver position sensors are associated with each unit to measure its position with reference to two degrees of freedom and to generate signals representative of this position. A machine position sensor measures the position of the machine with reference to a fifth degree of freedom and generates a signal representing this position. A computer responsive to these signals stores the geometrical features of the surface over which the machine is guided and controls each receiver in two dimensions to maintain it centered on the beam from the laser emitter. The computer also generates in real time command instructions applied to actuators controlling the machine, on the basis of these geometrical features.

Abstract: The alignment apparatus is intended for repairing welds using infrared radiation and a weldhead (30) inside a heat exchanger tube (14) in the water box (20) of a steam generator associated with a nuclear reactor. A power beam (PE, PL, PS) is transported to the axis (24) of a tube (14) to be treated via two motor-driven light deflectors referred to as an "emitter" (11) fixed adjacent to an access hole into the water box, and as a "receiver" (12) carried by a "carrier" (22) at the entrance to the tube to be treated. The power beam is surrounded coaxially by a visible beam (AE, AL, AS) which is used for establishing and maintaining an optical connection between the emitter and the receiver by means of retroreflectors (15) and an autocollimation mirror (17) carried by the receiver (12) and by detectors (16, 18) carried by the emitter (11).

Abstract: A device which measures the mutual coherence function of a laser beam. The device includes: a screen 1 in which openings 3 to 11 are disposed on the path of the beam 2 and allow pencils of light 19, 29 and 34 to pass; an interferometer constituted by an optical plate 13, a dihedron 14 and a mirror 21; a phase modulator 22 disposed on a branch of the interferometer; receivers 23 to 27 which receive the pencils of light 20 and 33 which emerge from the interferometer; and a processing circuit 36. Application to the analysis of a laser beam.

Abstract: The invention relates to a method for increasing the light produced by a laser beam on a target, consisting in reflecting this beam on a deformable mirror comprising several piezoelectric elements. The polarization voltage of each of the elements is successively increased by a predetermined DC voltage, this increase being maintained only if it corresponds to an increase in the light intensity diffused by the target. Application to the focussing of a data transmitting laser beam on an aerial.

Abstract: A gas laser device includes, in succession along an optical axis, a gas laser excited by a travelling wave, a convergent lens, two parallel-sided optical prisms adhering to one another in a symmetrical position in relation to the axis, and another convergent lens. The arrangement is such that two divergent elementary beams produced by the laser are brought together to have substantially less divergence.

Abstract: Gas laser comprising a flat electric energizing line consisting of an insulating layer inserted between two metallic layers brought to different potentials, one of whose edges is cut out in the shape of a parabola, one slot being provided in one of the layers, an active gaseous medium flowing in the slot, a circuit for setting up a substantially punctiform discharge between the metallic layers at the level of the focus of the parabolas. The electric line is arranged on a massive plate comprising on the one hand a cut provided in its lower face substantially opposite the slot and communicating with the latter and on the other hand two grooves provided on its upper face each having fitted in it a flexible seal and arranged opposite the walls of the slot.