Patent ID: 6778720
Filing Date: 2004-08-17
Classification: G01D

Abstract:
An apparatus for determining the phase of signal pulses which comprises:(a) a compensator; said compensator comprising a coupler, a delaying path and a modulating path; said delaying path comprising a delaying means and a reflector; said modulating path comprising a phase modulator and a reflector; whereby light pulses from a pulse light source are bifurcated and directed simultaneously by said coupler into said delay path and said modulating path and reflections from said delay path and said modulating path are combined by said coupler as pulse pairs; (b) one or more interferometers; (c) one or more optical receivers for converting the incoming light signals into electrical signals (d) a bi-directional coupling device for directing pulse pairs from said coupler to said one or more interferometers and for directing reflections from said one or more interferometers to said one or more optical receivers; (e) a digitizer for sampling the electrical signals exiting said one or more optical receivers in a fashion synchronous with the pulse light source; (f) a modulation signal generator; said modulation signal generator outputting a dual slope waveform comprised of alternating positive and negative slopes of equal magnitude for commanding said phase modulator in a fashion synchronous with the digitizer; (g) a demodulation means for cycle quadrant determination and output phase determination using the digitized electrical signals from both positive and negative modulation slopes; whereby output phase of signal pulses are determined by the demodulation of the digitized electrical signals.