Phase modulation and interpolation method for Michelson and grating interferometers

Abstract

In this paper, we discuss the fringe interpolation method for Michelson and grating interferometers using phase modulation. To obtain displacements (Lissajous diagram), we apply the sinusoidal phase modulation techniques to the initial phase between interferometer′s arms, the initial optical path different between interferometer′s arms, the refractive index and the frequency of light source. Two sine-wave-signals with 90° of phase different are obtained by synchronous detection to the interference signal. However, the original Lissajous diagrams both of Michelson and grating interferometers is deformed due to variation of the laser beam intensity. In this case, the normalized Lissajous diagrams are calculated, and the interpolation error will be discussed.