Interferometer with a single-mode waveguide coil

Claim 1

In an interferometer having a light source and a single-mode optical waveguide wound into a coil, said coiled waveguide having a surface at each end for acceptance of light into the waveguide and for the displaying of light in the waveguide, the improvements comprising a first optical directional coupler and an additional optical directional coupler, each of said optical directional couplers having four input/output ends with a pair of input/output ends at each end of the coupler, said first coupler having one input/output end of one pair of ends being axially coupled to one of said end surfaces of said coiled waveguide and a second input/output end of the one pair being coaxially coupled to the other of said end surfaces of said coiled waveguide, said first coupler having one end of the other pair of ends being coupled to a first light sensitive element and the other end of the other pair of ends being coupled to one end of a first pair of ends of the additional optical directional coupler, the other end of the first pair of ends of the additional directional coupler being closed by a light absorber, said additional optical directional coupler having one end of a second pair of ends being coupled to a second light sensitive element; and means for coupling said light source to a second end of the second pair of ends of the additional optical directional coupler, said means for coupling including imaging means for forming a real image of the light source on said second end said imaging means including imaging optics, and said means for coupling including means for making a magnified observation of the input coupling of light into the second end of the additional coupler.