Abstract: A holographic process is provided for recording-reading by means of index strata in the volume of a photoexcitable storage medium. This process consists in causing two beams to interfere in this medium during two successive writing steps by using writing radiations of different wavelengths. The reading of this medium is then effected by means of a third coherent radiation having for wave vector in the medium a linear combination of the wave vectors of said writing radiations.

Abstract: The invention relates to the interferometric detection of reciprocal and non-reciprocal effects affecting the propagation of optical radiation in a two-armed interferometer. The invention relates to a two-armed interferometer terminating by a photorefractive medium used as an interactive reflector according to the four-wave interferometer principle.The invention particularly applies to the measurement of physical quantities such as displacement, linear velocity, angular velocity, magnetic field, pressure and temperature.

Abstract: The invention relates to a process and device for measuring the optical core - mechanical sheath concentricity and the optical core ellipticity of an optical fibre. The process consists of injecting a light beam into a fibre, which has been previously bared at one of its ends. The analysis of the near field of this fibre by a detector performing a relative rotary movement with respect to said fibre provides details on the core - sheath concentricity and the core ellipticity, by carrying out a narrow band detection at the rotational frequency and at double its frequency.

Abstract: The invention relates to a device for measuring a magnetic field, comprising a source of rectilinearly polarized light. A magnetooptical medium is situated in the path of the beam, this medium being followed by a mirror refecting this beam. This medium is a medium of which the intrinsic propagation modes are polarized in right-hand and left-hand directions, and which retains the circular polarization. An element acting as a separator by polarization is situated between the source and the medium, a detector device being coupled to the same.

Abstract: The invention provides a process for forming a fiber keeping a circular polarization and a device for implementing this process.This process consists, during drawing and twisting of the fiber from a formable material source, in remelting on the surface a part of the volume of said fiber in a zone where it is subjected to twisting stresses.

Abstract: A heating device including a carbon dioxide laser beam directed towards a spherical mirror and then directed from an ellipsoidal mirror so as to concentrate the energy of said laser on a surface ring of a threadlike object.

Abstract: The invention relates to electro-optical media which make it possible to record holograms in real time. It consists in using a lamina of a selected material such as bismuth-silicon oxide, this lamina being subjected to a transverse electric field perpendicular to the fringes of the hologram to be inscribed, and in illuminating this lamina with a light beam which is not coherent with the two object and reference beams which interfere within this lamina.

Abstract: Optical fibre interferometer for measuring a current carried by a high voltage line of the type comprising a winding traversed by a feedback current, having at least one base at earth potential, incorporating the interferometer core and the feedback winding, an insulating member and a measuring head mounted on a conductor traversed by the current to be measured. The insulating member is a rigid member forming a support or, in a preferred variant, a tubular insulating member having a flexible wall and provided with skirts made from an insulating material with a rounded "water droplet" profile.

Abstract: The invention relates to a monomodal optical fibre hydrophone operating by elastooptical effect, which has an interferometer structure comprising a measuring arm, in which is arranged a very long monomodal optical fibre immersed in the interaction medium in which propagates the soundwave. A phase displacement is induced by an elastooptical effect on the soundwave propagating in the fibre, by a soundwave producing an acoustic pressure field in said medium. A reference arm establishes a reference optical path and the phase displacement, linked with the sound wave, is detected by interferometry between the two optical waves coming from these two arms. This two-armed interferometer is terminated by a photorefractive medium used as an interactive reflector in accordance with the four-wave interferometry principle.

Abstract: The invention relates to a process making it possible to produce a drawn object having a chiralic structure. This production process consists of subjecting the object to torsion during its drawing and simultaneously to hardening making it possible to fix part of the thus obtained torsional stresses in the structure.

Abstract: An interferometer having a tunable optical resonator using a monomode optical fiber as the light propagation medium. According to a preferred embodiment the fiber (1) is wound around a cylindrical mandrel (7) made from a piezoelectric ceramic material. Multiple reflections are ensured by reflecting deposits at the fiber ends. Rapid scanning of several orders of interference can be obtained by applying an alternating voltage V to the ceramic material.

Abstract: The invention relates to ring interferometers. It aims at making strictly reciprocal a ring interferometer of any known structure, by means of a mode filter which allow a particular mode to be selected among all the modes likely to be propagated in the loop and to arrive at the detection device; this filtering is carried out by a mode filter comprising for example a screen pierced with a hole or an integrated wave-guide or optical fiber portion which are advantageously monomode.

Abstract: An integrated optical structure creating directional coupling between two waveguides in which an index disturbance accompanying the guided photons is caused to act on two closely-spaced waveguides, this disturbance being produced by a progressive elastic wave with sloping wavefronts emitted by an electromechanical transducer.

Abstract: The current-measuring device in accordance with the invention comprises an optical fiber wound around the conductor in which flows the current to be measured, a laser source, means for separating the radiation emitted by the source towards the two ends of the wound fiber, and for recombining the radiation emerging from these two ends, a conductor circuit through which flows an adjustable reference current, a detection device supplying a signal characteristic of the interferences between the two waves emerging from the fiber, the reference current being adjusted so that the phase shift between the two contra-rotating waves in the fiber is zero, this current being then proportional to the current to be measured flowing in the principal conductor.

Abstract: A directional coupling device for single multi-mode optical fibers which are disposed coaxially in a transparent body of the coupling device, a suitable space filled with an immersion medium being formed between the end faces of the two fibers; means for introducing light rays and photo-sensitive means for picking up the dispersion flux are respectively arranged on at least one of the ends of the body of the coupling device.