Abstract: An appliance for measuring polarization mode dispersion (PMD) of a waveguide (2) comprises a source (1, 6) of wide-band polarized light, an interferometer (5) capable of receiving a light beam (21) sent by the source (1, 6), a detector (3) capable of detecting the light beam (25) from the interferometer (5), and an electronic processing unit (4) connected to the detector (3), capable of extracting a value .tau. representative of the polarization mode dispersion of the waveguide (2). The interferometer (5) divides a measuring light beam (22) sent by the source (1) into two interference light beams (23, 24). The measuring appliance comprises at least one birefringent element (17) positioned on the interferometer (5), capable of producing an algebraic difference of relative phase shifts in each of the two interference light beams (23, 24) equal to .pi..

Abstract: The invention relates to improvements to methods and devices for determining the contact angle of a drop of liquid placed on a substrate. The device comprises: a support 12 for a substrate 11 which receives a drop of liquid 9; a light source 1; optical means, formed for example by a plate with parallel faces 21 rotatable about its axis 22 and whose inclination with respect to the axis may be modified, with a reflecting prism 5a, for forming a primary beam 6a, advantageously annular, striking the interface 8 between drop and substrate; a receiving surface 13a, 13b formed by a reflection diffusing surface; a reflecting surface 17; and a camera C.

Abstract: The discriminating device comprises an optical coupler (4) having at least three ends (5 to 8) to which are connected a semiconductor source of light (1) whose intensity is modulated, a semiconductor photoconductor (2) and an optical probe constituted by a multi-mode optical fibre (3) whose end has a pointed shape. This discriminating device is in particular applicable in a device for measuring the voluminal fraction of at least one fluid of a current of non-mixible fluids.