POLARIZATION SELECTING DEVICE, LIGHT SOURCE MODULE AND FIBER-OPTIC GYROSCOPE

摘要

Small-sized polarizers are required for optical fiber gyroscopes. The fiber-type polarizer or the metal-dielectric multilayer polarizer is small-sized and suitable to conventional gyroscopes. But these polarizers are expensive. A source-sensitive fiber-optic gyroscope is a novel, simplified gyroscope which demands a suitable, simplified, low-cost polarizer. A birefringent crystal having surfaces inclining at about 45 degrees to the anisotropic axis can spatially separates a beam into an ordinary beam with polarization perpendicular to the anisotropic axis and an extraordinary beam with polarization having a component of the anisotropic axis. A polarization selecting device is produced by-facing ends of two optical fibers to both surfaces of a birefringent crystal. A beam emitted from a fiber is separated into an ordinary beam and an extraordinary beam. Either of them enters the core of the other beam as a propagating beam. A light source module is produced with a light emitting device, a birefringent crystal and an end of an optical fiber. The birefringent crystal divides a beam from the light source into an extraordinary ray and an ordinary ray. Either of them is introduced into the fiber. Thus the light source module emits linearly-polarized beams. The light source module is suitable for the source-sensitive fiber-optic gyroscope, because the system dispenses with a polarizer. When a lens has a non-effective peripheral part, the dispersion of beams should be suppressed by interposing a pinhole plate between the lens and the light source.