Abstract: A fiber optic sensor coil is wound from a length of optical fiber with the mid-point of the optical fiber at the mid-point of the innermost layer of the coil and subsequent layers of the coil each have alternating turns of the two sections of the fiber emanating from the mid-point. The layers of alternating turns are formed by first winding a portion of one segment in such a fashion that adjacent turns are spaced apart by a distance equivalent to the diameter of the optical fiber. The layer is completed by winding a portion of the other segment such that the turns of the other segment are disposed between adjacent turns of the one segment. The number of turns in adjacent layers are unequal such that the turns of a next layer are arranged in grooves formed between two adjacent turns of optical fiber in the previous layer.

Abstract: A fiber optic sensor coil is wound from a length of optical fiber with the mid-point of the optical fiber at the mid-point of the innermost layer of the coil and subsequent layers of the coil each have alternating turns of the two sections of the fiber emanating from the mid-point. The layers of alternating turns are formed by first winding a portion of one segment in such a fashion that adjacent turns are spaced apart by a distance equivalent to the diameter of the optical fiber. The layer is completed by winding a portion of the other segment such that the turns of the other segment are disposed between adjacent turns of the one segment. The number of turns in adjacent layers are unequal such that the turns of a next layer are arranged in grooves formed between two adjacent turns of optical fiber in the previous layer.

Abstract: An interferometric fiber-optic gyro system includes a light source and a plurality of optical fiber rings employed to measure angular displacement along three axes. Optical circuit elements interposed between the source and the rings include an optical switch for periodically applying the optical signal to each of the rings individually along three separate optical transmission paths. Included in each of the optical transmission paths is a modal filter, including a polarizer, and a beam splitter which provides two separate beams to the optical ring for counter-propagation through the ring. Compensating birefringent devices are added in the optical circuits to compensate for a residual birefringence introduced by the various optical elements in the circuits. The characteristics of the compensating devices consist of predetermined lengths of polarization preserving, single-mode optical fiber. The birefringence of each of the optical devices is characterized in terms of a total number of beat lengths.