A Fabry-Perot sensor for measuring an inclination. The sensor is fixed on a static detected object, where a mass block is flexibly connected to a top plate, thus the line between the center of gravity of the mass block and the connecting point on the top plate is perpendicular to the horizontal plane. This creates a Fabry-Perot cavity between a reflecting surface disposed at one end of the mass block and the end of an optic fiber. When the detected object is tilted, the line between the center of gravity of the mass block and its connecting point on the top plate remains perpendicular and the F-P cavity length will have a variation in length. The change of cavity length is measured in accordance with the Fabry-Perot principle, thereby the tilting angle, which is the inclination of the detected object, of the mass block is measured.

A fiber optic sensor device comprising an optical fiber with a multilayer coating on the optical fiber at least in a fiber section of the optical fiber. The multilayer coating comprises a chrome layer on the optical fiber, a metal layer such as a copper layer on the chrome layer and an indium or lead layer on the metal layer. The indium or lead layer having a thickness larger than thicknesses of the chrome and metal layers, preferably with a thickness about equal to the radius of the optical fiber.

There is described a method for interrogating optical fiber comprising fiber Bragg gratings (FBGs), using an optical fiber interrogator. The method comprises (a) generating an initial light pulse from phase coherent light emitted from a light source, wherein the initial light pulse is generated by modulating the intensity of the light; (b) splitting the initial light pulse into a pair of light pulses; (c) causing one of the light pulses to be delayed relative to the other of the light pulses; (d) transmitting the light pulses along the optical fiber; (e) receiving reflections of the light pulses off the FBGs; and (f) determining whether an optical path length between the FBGs has changed from an interference pattern resulting from the reflections of the light pulses.

This invention describes the structure and function of an integrated multi-sensing systems in stacked configuration. Integrated systems described herein may be configured to form a microphone, pressure sensor, gas sensor or accelerometer. The method uses Fabry-Perot Interferometer in conjunction with light source and a photodetector integrated in stacked configuration. It also describes a configurable method for tuning the integrated system to specific resonance frequency using electrostatic actuators.

Apparatus and associated methods relate to determining the wavelength of a narrow-band light beam. The narrow-band light beam is passed through an optical filter. The optical filter has complementary and monotonically-varying transmission and reflection coefficients within a predetermined band of wavelengths. The predetermined band of wavelengths includes the wavelength of the narrow-band light beam. A first photodetector detects amplitude of a first portion of the narrow-band light beam transmitted by the optical filter. A second photodetector detects amplitude of a second portion of the narrow-band light beam reflected by the optical filter. The wavelength of the narrow-band light beam is determined, based on a ratio of the determined amplitudes of the first and second portions of the narrow-band light beam transmitted and reflected, respectively.

Optomechanical device for actuating and/or detecting movement of a mechanical element, in particular for gravimetric detection. It includes a support with a mechanical element anchored to the support which is designed to move relative to the element, and a device for actuating and/or detecting movement or of variations in frequency of movement of the element. A portion of the device is arranged beneath at least part of the element, between the element and the support. The device includes a fixed optical device with at least one optical waveguide arranged beneath all or part of the element at a determined distance from the element, and which is designed to propagate at least one optical wave having a given wavelength designed to interact with the element. The optical waveguide is at a determined distance from the mechanical element so that the evanescent field of the optical waveguide interacts with the mechanical element.

The invention relates to an absolute position measuring device, comprising an optical fiber, an optical strain sensor in optical communication with the optical fiber, and a volume of material deforming under influence of a magnetic field. The optical strain sensor is arranged for sensing deformation of the volume of material. Further, the device is arranged for multi-dimensional position measurement.

A transformer system includes a transformer and a transformer tank. The transformer tank houses the transformer in a bath of a dielectric fluid. The transformer system also includes a controller, and a fiber optic sensor communicatively coupled to the controller. The fiber optic sensor is disposed in the dielectric fluid and operative to provide an output that varies with the level of the dielectric fluid. The controller is operative to determine the level of the dielectric fluid based on the output of the fiber optic sensor.

A transformer system includes a transformer and a transformer tank. The transformer tank houses the transformer in a bath of a dielectric fluid. The transformer system also includes a controller, and a fiber optic pressure sensor communicatively coupled to the controller. The fiber optic sensor is disposed in the dielectric fluid and operative to provide an output that varies with the pressure of the dielectric fluid. The controller is operative to determine the pressure of the dielectric fluid based on the output of the fiber optic pressure sensor.

Methods are proposed for compensation of distortion in fiber Fabry-Perot interferometric (FFPI) sensors induced by dynamic wavelength dependent attenuation in subsurface wells. The methods involve measurement techniques that correct the reflective spectrum from one or more FFPI sensors utilizing a background low frequency spectrum for normalization.