Abstract: An apparatus and a method are provided for measuring an ambient physical parameter applied to a highly birefringent sensing fiber. A light source emits a low coherence light beam into a sensing fiber subjected to an ambient physical parameter. A collector receives the output light beam of the sensing fiber and a splitter divides the output light beam into two orthogonally polarized output beams and subjects the two orthogonally polarized output beams to a range of relative delays. A recombiner combines the two orthogonally polarized output beams to produce an interference pattern, and a detector detects intensities of the interference pattern over the range of delays. A calculating device determines the ambient parameter from the intensities with improved accuracy.

Abstract: A fiber-optic strain gauge manometer and a method thereof are for measuring pressure of a fluid, to be respectively connected to a light source and a measurement apparatus. The manometer comprises: a cylindrical hollow body, acting as a pressure transducer, having an inlet by which the fluid can get inside, free ends such that longitudinal and circumferential strains are generated in the hollow body by the pressure of the fluid, thereby producing a dilatation of the hollow body, and a highly birefringent optical fiber having a sensing portion bonded to the outer surface of the hollow body along a longitudinal path such that its birefringence changes when the sensing portion is subjected to the dilatation of the hollow body. A polarized light beam is generated by the light source and transmitted in a form of two polarization eigenstates each parallel to one of two parallel principal birefringence axes of the birefringent optical fiber.

Abstract: The method is for measurement of pressure applied to a sensing element comprising a cholesteric liquid crystal being connected to multimode optical fibers for communication with a light source and a device for measurement of light intensity. The method resides in guiding a light beam of predetermined wavelength generated by the light source toward a layer of the cholesteric liquid crystal using one of the multimode optical fibers. The light beam reflected by the layer is collected using another of the multimode optical fibers being connected to the device for measurement of light intensity. This device measures then the intensity of the reflected light beam, such that a value indicative of the pressure as a function of the measured intensity can be carried out. This method is particularly well adapted for measuring pressure up to 100 MPa with a good linear response and sensitivity for specific ranges of pressure useful in industrial applications.

Abstract: The present disclosure describes a birefringent optical fiber device for measuring of ambient pressure in a stabilized temperature environment, when connected respectively to a light source and a measuring apparatus. The device comprises a first device for receiving polarized light from the light source; a birefringent fiber being connected to the first device for receiving the polarized light which has light signal components polarized along two orthogonal polarization axes of the berefringent fiber, the berefringent optical fiber having a preselected length determined by a range of pressures to be measured; and a second device for receiving light signals emitted from the birefringent fiber, the light signals having elliptical polarization state characterized by major and minor axes, whereby cross-talk between the light signal components along the polarization axes being responsive to the ambient pressure in the environment.