Abstract: Coder of position of a first element in displacement relatively to a second element, the latter including an optical system provided with at least one coherent light source emitting a beam intended to interfere, after collimation in a diaphragm, with the second element and at least one photodetector with contiguous cells in a line for detection of the light signal after interference. The second element includes a succession of primary coding cells provided with diffraction holograms each defining therein a single location, the cells interfering in succession with the light beam in the course of their relative displacement. The diffracted signal is sent to the photodetector or photodetectors for measurement of absolute position. The coder includes a series of secondary coding cells provided with diffraction holograms interfering successively with the light beam.

Abstract: A method for determining the position of one of two components in relative motion with respect to each other, using optical means, comprises: directing at least one light beam emitted by a light source attached to one component towards a diffractive support attached to the second component, calculated and manufactured for generating an optical signal indicative of the positioning of said support, the optical signal being produced by the diffractive support in transmission and/or in reflection; detecting and reading at least one optical code formed by said signal, which corresponds to a unique position of the diffractive support relatively to the beam; and assigning a position to each detected optical code.

Abstract: A magnetic actuator, for example a magnetic bearing, embodies a fixed part and a mobile part. These parts are ferromagnetic and form an airgap between them extending parallel to a predetermined first direction. The magnetic actuator further embodies a nonmagnetic wall interposed in the airgap. The wall is that of a confinement chamber, for example. In this magnetic actuator one of the fixed and mobile parts embodies fingers penetrating the nonmagnetic wall and directed towards the other of the fixed and mobile parts.