Patent ID: 8773665

Claim:
A compact fiber optic gyroscope comprising: a first housing defining an interior and comprising: a base plate portion defining an annular cavity, and a top cover portion configured to be coupled to the base plate portion to define the interior of the first housing, wherein the top cover portion defines an input/output opening; a planar optical fiber loop having a first end and a second end and at least partially secured by the annular cavity of the base plate portion, wherein the planar optical fiber loop is disposed in the first housing around the periphery of the interior of the first housing and defines an inner circumference; a transceiver module disposed in the interior of the first housing within the inner circumference of the planar optical fiber loop, wherein the transceiver module comprises: a second housing; a non-coherent light source disposed in the second housing for producing a first beam of light; an optical circulator disposed in the second housing and in the path of the first beam of light to produce polarized second and third beams, with polarization orthogonal to each other; a focusing lens disposed in the second housing and positioned in an optical path between the non-coherent light source and the optical circulator to focus non-coherent light from the non-coherent light source to a focus point beyond the optical circulator; and first and second photodiodes disposed in the second housing and coupled to the optical circulator, wherein the first photodiode is a transmit monitor photodiode coupled to the second beam, and the second photodiode is a receiver photodiode; a phase modulator mounted on the base plate portion and disposed in the interior of the first housing within the inner circumference of the planar optical fiber loop and coupled to the third beam from the transceiver module to produce fourth and fifth beams coupled to the first and the second ends, respectively, of the optical fiber loop, and receiving return sixth and seventh beams from the second and the first ends, respectively, of the fiber loop, and coupling the return sixth and seventh beams to the receiver photodiode in the transceiver module; a processor disposed in the interior of the first housing within the inner circumference of the planar optical fiber loop and coupled to the receiver photodiode for determining a phase relationship between the return sixth and seventh beams and thereby determining the rotational rate of the planar optical fiber loop with respect to an axis; and an input/output connector operatively coupled to the processor and configured to at least report inertial guidance information, wherein the external input/output connector extends through the input/output opening of the top cover portion.