Patent ID: 8437006

Claim:
A displacement sensor apparatus for measuring the displacement of a non-stationary target comprised of: a coherent electromagnetic radiation source having a power in the range of 1 mW to 2 mW and capable of frequency modulation, said electromagnetic radiation source produces an electromagnetic radiation beam; a waveguide coupler operatively coupled to said coherent electromagnetic radiation source with a first optical fiber; an electro-magnetic radiation absorption component comprised of refractive index gel coupled to said waveguide coupler with a second optical fiber; an interferometric waveguide coupled to said waveguide coupler with a third optical fiber; an extension waveguide having an end face angled within a range of 5° to 15°; an interface between said interferometric waveguide and said extension waveguide creating a back reflecting discontinuity; wherein said electromagnetic radiation beam passes through said waveguide coupler which distributes a first portion of said electromagnetic radiation beam to said electro-magnetic radiation absorption component and a second portion of said electromagnetic radiation beam through said interferometric waveguide and said extension waveguide; wherein said interface generates an electromagnetic radiation reference beam from said portion of said electromagnetic radiation beam distributed through said interferometric waveguide and said extension waveguide; a target electromagnetic radiation beam reflected from said non-stationary target and received by said extension waveguide, wherein said non-stationary target is at a distance from said end face within a range of 0 to a few micrometers; an electromagnetic radiation detector configured to detect interference between said electromagnetic radiation reference beam and said target electromagnetic radiation beam, wherein said electromagnetic radiation detector is coupled to said waveguide coupler with a fourth optical fiber and operatively coupled to a signal processor.