Abstract:
A fiber optic sensor interrogation system with inbuilt passive power limiting capability based on stimulated Brillouin scattering that provides improved safety performance for use in explosive atmospheres.
Abstract:
A method and device for monitoring oil field operations with a fiber optic distributed acoustic sensor (DAS) that uses a continuous wave laser light source and modulates the continuous wave output of the laser light source with pseudo-random binary sequence codes.
Abstract:
A sensor (1) has a light conductor (2) having a grating (FBG), a cavity (5), and a transparent cavity end wall (4), a light emitter for directing light through the conductor, and a light detector for detecting reflected light, and a processor. The processor is adapted to analyse light reflected due to the grating (FBG, 6) to determine an indication of temperature, light reflected from the end (7) of the cavity (5) to determine an indication of pressure, and also light reflected from the outer surface (8) of the cavity wall (4) to determine an indication of refractive index of a medium outside said cavity wall. The processor may use one output to compensate another, for example pressure and temperature may be used to compensate for variation in refractive index.
Abstract:
Apparatus and a method for monitoring various conditions of a vehicle structure including an optical sensor comprising an optical fiber bearing a photonic crystal mounted to one end, an interrogation system including an optical signal generator interfacing with one or more of the optical sensors located remotely from the interrogation module, and a method of monitoring the vehicle structural health using the interrogation system.
Abstract:
The present invention relates to a method and system of array imaging that extends or maximizes the longevity of the sensor array b minimizing the effects of photobleaching. The imaging system has a light source (12), a variable exposure aperture (14), and a varia filter system (16). The system extends the longevity of sensors (28) by 1) using the variable exposure aperture to selectively expose sections of the sensor array containing representative numbers of each type of sensor, and/or 2) using the variable filter system to control the intensity of the excitation light, providing only the intensity required to induce the appropriate excitation and increasing intensity over time as necessary to counteract the effects of photobleaching.
Abstract:
A multitasking optical fiber probe (10) for collecting dosimeter information from more than one position in a sample. The basic principle of the present invention involves using one or more different sensor zones (20,22,24,26,28,30) along the length of the fiber (14) each with a different photoactive constituent having a sufficiently unique emission spectra (spectral or temporal) to enable deconvolution of the emission spectra by the computer (46) and therefore correlation of the detected parameter with the position of the sensor zone along the length of the optical fiber. In the broadest form of the invention the probe is embodied by only one sensor zone located at some point along the length of the fiber spaced away from the end face of the fiber. More than one different photoactive constituent could be incorporated into a single sensor zone for measuring several factors in the vicinity of the sensor zone.
Abstract:
A grating structure is written in a photosensitive waveguide (17) by dividing a coherent beam (10) into at least three beams (12, 13, 14), and interfering them at the waveguide (17). The beams may comprise a zero order beam (12) and two first order beams (13, 14) diffracted by a phase mask (11), and their relative phases and amplitudes may be modulated to control and/or tune the grating period and shape. The method allows grating structures to be written in which a first order grating and a second order grating are superimposed.