Interferometer for measuring displacement information of an object

Abstract

An interferometer includes a laser beam source, a light wave dividing and synthesizing portion for 2-demultiplexing and irradiating a laser beam irradiated from the laser beam source on a measuring target and synthesizing a light having each displacement information, a multiphase interference light generating portion for generating, from a synthesized laser beam, a first interference light having a first phase, a second interference light having a second phase which is different from the first phase by 180 degrees, a third interference light having a third phase which is different from the first phase by 90 degrees, and a fourth interference light having a fourth phase which is different from the first phase by 270 degrees, a 3-phase signal generating portion for generating a 3-phase signal having a phase difference of 90 degrees on the basis of first to fourth interference signals based on the first to fourth interference lights, and a 2-phase signal generating portion for carrying out a vector synthesis over the 3-phase signal having a phase difference of 90 degrees, thereby generating a 2-phase signal having a phase difference of 90 degrees.