An improvement for a fiber interferometer gyro provides for greater rotation rate sensitivity. The gyro has a single mode fiber coiled about an identical area a great number of times. A single external laser sends pulses of energy which are split and passed in opposite directions through the coiled fiber and a pair of optical amplifiers inserted to amplify the energy pulses. This permits the length of the coiled fiber to be increased and, hence, provides for greater interferometer sensitivity.
A fiber interferometer gyro employing a continuous, integral looped single-mode fiber is coupled to bidirectionally transmit clockwise and counterclockwise pulsed beams of light through a coiled continuous integral single-mode fiber from a laser to a pair of detectors. A suitably polarized piezoelectric cylinder is fitted about a portion of the continuous integral single-mode fiber to change the refractive index of that portion of the continuous integral single-mode fiber when appropriate electric fields are impressed across it. Changing the refractive index in only that portion of the continuous integral single-mode fiber results a selective phase biasing between the clockwise and counterclockwise traveling pulsed beams so that a rotation displacement of the interferometer gyro is more easily detected. This enhanced capability does not compromise the interferometer's effectiveness since its integral, continuous path is not broken nor are other elements introduced in the light pathway provided by the continuous single-mode fiber.
A fibre optic gyroscope including a fibre optic loop, a radiation source for generating a broadband signal, splitting means for splitting radiation from the source into two components and inserting them into the loop in clockwise (CW) and counter clockwise (CCW) directions, recombining means for recombining the components interferometrically to give an indication of rotation rate of the loop, characterized in that there is further provided amplification means for amplifying both components travelling within the loop.
In a optical fiber coil arrangement for use in rotation sensors, for example, axial and/or radial errors can be reduced or substantially eliminated by employing trimming lengths of the first and second ends of the optical fiber used to wind the coil. The first and second ends are spatially separated from one another so as to reduce such errors. The trimming lengths may be in the form of trimming turns. To eliminate axial errors, the first end is formed into a first number of trimming turns and the second end is formed into a second number of trimming turns so that the first and second number of trimming turns are spatially offset from each other in an axial direction. To eliminate radial errors, the first end is formed into a first number of trimming turns and the second end is formed into a second number of trimming turns so that the first and second number of trimming turns are spatially offset from each other in a radial direction. Radial and axial compensation may be combined.
In a fiber optic coil arrangement for use in rotation sensors, for example, axial or radial errors can be reduced or substantially eliminated by negatively trimming the fiber optic coil. As a result of the negative trimming, a sufficient amount of the predictable turns of the optical fiber is removed from the fiber optic coil so as to interrupt the predetermined pattern with which the fiber optic coil is wound in order to thereby reduce axial or radial related errors which would have otherwise resulted. Alternatively, the fiber optic coil may be negatively trimmed by terminating winding of the fiber optic coil before the predetermined pattern of the fiber optic coil has been completed. The point at which winding is terminated may be selected so as to reduce axial or radial related errors to a desired level.
