Patent ID: 9204800
Filing Date: 2015-12-08
Classification: A61B,G01B

Abstract:
1. A signal interrogation system comprising: an optical coupler to split input laser beam into a first laser beam as a power reference and a second laser beam, the optical coupler being coupled to a first path for the first laser beam and a second path for the second laser beam; an optical circulator disposed in the second path; a bi-directional optical switch having on one side a single channel end and on another side multiple channel ends with multiple switchable channels, the bi-directional optical switch being disposed in the second path, with the single channel end oriented toward the optical circulator; a plurality of optical fibers coupled to the multiple channel ends of the bi-directional optical switch, wherein the bi-directional optical switch switches the second laser beam among the plurality of optical fibers coupled to the multiple switchable channels, the plurality of optical fibers directing the second laser beam to a target and receiving interference optical signals based on reflection/scattering lights of the second laser beam from the target, the interference optical signals for a given optical fiber of the plurality of optical fibers being produced by coupling back the reflection/scattering lights of the second laser beam from the target to the given optical fiber and interfering with lights reflected at a reference surface for the given optical fiber from the second laser beam; an interference optical signals path coupled to the optical circulator to receive the interference optical signals from the bi-directional optical switch; a balanced photo detector to measure a power difference between the interference optical signals and the power reference; a variable optical attenuator disposed in the first path between the optical coupler and the photo detector; and a computer coupled to the balanced photo detector to receive the measured power difference, and to the variable optical attenuator to control the variable optical attenuator to match power of the first laser beam as the power reference and the interference optical signals directed to the photo detector based on the measured power difference.