OPTICAL INTERFEROMETER

PROBLEM TO BE SOLVED: To eliminate the need for a compensator and to simplify the adjustment of an optical axis in an optical interferometer. SOLUTION: An optical interferometer is provided with a first beam splitter 2 to branch incident light 1 into two optical paths of reflected light and transmitted light which intersect each other at right angles, a first reflector 13 to reflect reflected light from the first beam splitter 2 to a parallelly translated location with respect to the reflected light, a second reflector 14 to reflect transmitted light from the first beam splitter 2 to a parallelly translated location with respect to the transmitted light, a second beam splitter 12 to reflect light reflected by the second reflector 14 on one hand and to transmit and multiplex light reflected by the first reflector 13, and a light receiver 5 to receive light multiplexed by the second beam splitter 12. The first and second beam splitters 2 and 12 are mounted to the same plane of a holding member 20. The first beam splitter 2 comprises a reflecting plane 2a on the side of the second reflector 14, and the second beam splitter 12 comprises a reflecting plane 12a on the side of the first reflector 13.