Abstract: Disclosed is a Rotation sensor with a light source, a light detector, an internal part having a first lateral surface, which is globally cylindrical and convex, and an external part having a second lateral surface which is globally cylindrical and concave. The first and second lateral surfaces both have a same central axis defining a rotation axis for a relative rotation between the internal part and the external part the angle of which this rotation sensor can measure. A first grating is arranged at the first lateral surface with its grating lines parallel to the rotation axis, and a second grating is arranged at the second lateral surface with its grating lines parallel to said rotation axis.

Abstract: Disclosed is a Rotation sensor with a light source, a light detector, an internal part having a first lateral surface, which is globally cylindrical and convex, and an external part having a second lateral surface which is globally cylindrical and concave. The first and second lateral surfaces both have a same central axis defining a rotation axis for a relative rotation between the internal part and the external part the angle of which this rotation sensor can measure. A first grating is arranged at the first lateral surface with its grating lines parallel to the rotation axis, and a second grating is arranged at the second lateral surface with its grating lines parallel to said rotation axis.

Abstract: For increasing the power emitted by surface emitting lasers and for improving the spatial coherence of the laser beam, emitted in particular by disk lasers, microchip lasers and VCSELs having a relatively wide emitting area, the invention proposes to select a low order transverse cavity mode by means of a mirror structure (12) of high reflectivity, and of high angular selectivity. The mirror structure comprises a multilayer (14) receiving the optical beam (24) and a resonant grating mirror (16) following the multilayer and arranged for highly reflecting the optical beam in a narrow angular range at each side of a determined incidence angle.

Abstract: For increasing the power emitted by surface emitting lasers and for improving the spatial coherence of the laser beam, emitted in particular by disk lasers, microchip lasers and VCSELs having a relatively wide emitting area, the invention proposes to select a low order transverse cavity mode by means of a mirror structure (12) of high reflectivity, and of high angular selectivity. The mirror structure comprises a multilayer (14) receiving the optical beam (24) and a resonant grating mirror (16) following the multilayer and arranged for highly reflecting the optical beam in a narrow angular range at each side of a determined incidence angle.