DIFFRACTION INTERFEROMETER Russian patent published in 1996 - IPC

FIELD: checking quality of optical devices. SUBSTANCE: device has coherent light source, illuminating system, projection lens, light separator, diffraction plate, quarter-wave phase plate, which main axis azimuth is half of right angle, device for recording of interference pattern with polarizer, which transmission axis azimuth is zero. Illuminating system is designed as multiple-mode optical fiber, which is connected to interference modulator. Polarizer which transmission axis azimuth is right angle is located at output end of fiber. This results in averaging of spot structure by variation of partial illumination of immovable diffraction plate. This is achieved by effect of inter-mode interference in multiple-mode optical fiber. This results in increased decreased drop of contrast of interference pattern. EFFECT: decreased measuring error caused by spot structure, which adds noise in interference pattern. 2 dwg