Abstract: An apparatus for sensing acoustic energy in a borehole penetrating the earth includes an optical interrogator and a sensing optical fiber having a length Ls optically coupled to the optical interrogator and configured to sense the acoustic energy to provide sensed acoustic data. The apparatus also includes a reference optical fiber having a length Lr optically coupled to the optical interrogator to provide reference data, wherein the optical interrogator corrects the sensed acoustic data using the reference data to provide corrected sensed acoustic data.

Abstract: A method and apparatus for measuring a pressure. A pressure gauge includes a first plate having a resonant frequency related to a pressure at the pressure gauge. The first plate is thermally-excited at a selected frequency, and a sensor measures a first power level of a first light having a first wavelength reflected from the first plate and a second power level of a second light having a second wavelength reflected from the first plate. A processor determines a thermal drift in the resonant frequency of the first plate due to the thermal excitation of the first plate from the first power level and the second power level, corrects a pressure measurement determined from the resonant frequency of the first plate for the thermal drift of the resonant frequency, and operates a device based on the pressure measurement.

Abstract: An apparatus for sensing acoustic energy in a borehole penetrating the earth includes an optical interrogator and a sensing optical fiber having a length Ls optically coupled to the optical interrogator and configured to sense the acoustic energy to provide sensed acoustic data. The apparatus also includes a reference optical fiber having a length Lr optically coupled to the optical interrogator to provide reference data, wherein the optical interrogator corrects the sensed acoustic data using the reference data to provide corrected sensed acoustic data.

Abstract: Downhole fiber optic interrogation systems are described. The systems include a fiber optic control system, a first sensing system, a second sensing system, an optical fiber disposed within a well, and an optical switch arranged between the optical fiber and the first and second sensing systems, wherein the fiber optic control system performs time division multiplex control of the optical switch wherein the first sensing system is operably connected to the optical fiber and the second sensing system is not connected to the optical fiber, and further controls the optical switch such that the second sensing system is operably connected to the optical fiber and the first sensing system is not connected to the optical fiber.

Abstract: A system and method to determine temperature include an optical fiber and at least two pulse laser sources to transmit light pulses with at least two wavelengths into the optical fiber. The system also includes an optical path length modulator to modulate the optical path length of the optical fiber as the light pulses are transmitted into the optical fiber. At least two photodetectors detect backscatter reflected in the optical fiber, and a processor determines the temperature based on the backscatter.

Abstract: Downhole fiber optic interrogation systems are described. The systems include a fiber optic control system, a first sensing system, a second sensing system, an optical fiber disposed within a well, and an optical switch arranged between the optical fiber and the first and second sensing systems, wherein the fiber optic control system performs time division multiplex control of the optical switch wherein the first sensing system is operably connected to the optical fiber and the second sensing system is not connected to the optical fiber, and further controls the optical switch such that the second sensing system is operably connected to the optical fiber and the first sensing system is not connected to the optical fiber.

Abstract: A method and apparatus for measuring a pressure. A pressure gauge includes a first plate having a resonant frequency related to a pressure at the pressure gauge. The first plate is thermally-excited at a selected frequency, and a sensor measures a first power level of a first light having a first wavelength reflected from the first plate and a second power level of a second light having a second wavelength reflected from the first plate. A processor determines a thermal drift in the resonant frequency of the first plate due to the thermal excitation of the first plate from the first power level and the second power level, corrects a pressure measurement determined from the resonant frequency of the first plate for the thermal drift of the resonant frequency, and operates a device based on the pressure measurement.

Abstract: A system and method to determine temperature include an optical fiber and at least two pulse laser sources to transmit light pulses with at least two wavelengths into the optical fiber. The system also includes an optical path length modulator to modulate the optical path length of the optical fiber as the light pulses are transmitted into the optical fiber. At least two photodetectors detect backscatter reflected in the optical fiber, and a processor determines the temperature based on the backscatter.

Abstract: A process and device for analyzing image data and performing automatic optimization of a black and white image created by a scanner. The process and device performs dynamic thresholding by approximating the information level and the background level at every pixel in the image, the threshold being calculated as a function of the background and information levels at that point, and a characterization process step comparing the pixel intensity at that point with the threshold, so that if the pixel is darker, it is considered to be black, or if it is lighter, it is considered to be white.