Patent ID: 6329648
Filing Date: 2001-12-11
Classification: G01D

Abstract:
A fiber optical system for sensing a small physical displacement of a light reflecting element in response to a measurement parameter to be measured, said system including:at a first location,a control unit having light means for generating light having a relatively long wavelength as compared to the wavelength of light;phase sensing means for detecting a phase change between reflected light and reference light from a second location, andan oscillator connected to said light means where the frequency of the light means is controlled by the said oscillator and the oscillator is controlled by said phase sensing means;at the second location,a sensor unit having a parameter displacement means for receiving light from said light means and for generating reflected light, said parameter displacement means having small physical displacements in response to a measurement parameter, andlight delay means coupled to said parameter displacement means for producing a large change in phase between reflected light in response to said parameter displacement means and reference light, andreference light means for providing reference light at said second location where said reference light is derived from said generated light at said second location, andoptic fiber line means for coupling said control unit to said sensor unit so that a physical displacement in the parameter displacement means can be determined at the first location from the control of the light means.