In a traditional dual optics routes Michelson interferometer, the critical time delay is acquired by scanning one mirror that needs a precision physical translation mechanism. The so-called translation mechanism usually dominates the risk, cost, power consumption, and performance of such instruments which limits the development of interference spectrometer. This paper describes the principle of a novel temporal modulated interference spectrometer that generates time delay by using birefringence crystal because of speed difference and the refraction indexes between the ordinary and the extraordinary component. A greater optical path difference can be abstained by cascading a series of wave plates that interlaced with a series of achromatic ferroelectric liquid crystal switches. Through the simulation analysis and experiment of the principle of polarization interference spectrometer, it demonstrates the validity of the instrument principle and data inversion method. © 2017 IEEE.