Abstract: A differential transducer for measuring the curvature variations of a surface such as the surface of a diaphragm (5). The transducer includes an assembly of two L-shaped optical elements (6, 7) having first legs (8) intended to be mounted on the surface in such a way that the outer faces of both second legs (9) extend substantially in parallel to each other and at a right angle away from the surface, an optical cavity (19) defined therebetween, a laser source (17) having a beam (16) directed parallel to the surface onto the assembly and perpendicularly to the outer faces of the second legs (9), and a photodetector (18) for receiving the beam after having passed through the cavity (19). The optical elements (6, 7) are provided with three support tips (10, 11, 12) firmly applied against the surface and arranged at the corners of an equilateral triangle whose symmetry axis is parallel to the beam (16) axis, one of the support tips (10) on the symmetry axis being located close to one of the second legs (9).

Abstract: A very low amplitude interferometer suitable for detecting gravitational waves is disclosed. The interferometer has an optical cavity consisting of a glass plate sandwiched between two three-dimensional interferometric arrays and contacting a body in which micro-vibration is to be sensed. The interface between the interferometric arrays and the glass plate entraps thin layers of air. A coherent light source is used to illuminate one of the interferometric arrays. Micro-vibrations transmitted through the glass plate will affect the air layers sufficiently to render these vibrations detectable through interference patterns created by the reflected coherent light on a display screen.

Abstract: The invention relates to an optical modulator allowing to modulate a coherent light beam (2) by an optical signal (4). According to the invention, it comprises an optical cavity (3) composed of two superposed glass substrates (8, 9), each carrying an interferometric tridimensional lattice, said coherent beam (2) being susceptible to be directed on a first surface of said cavity (3), whereas said optical modulation signal (4) is directed against said first surface or the opposite surface of this cavity, the output signal of this modulator being constituted by said beam after reflection on said optical cavity (3).