Patent ID: 8130378

Claim:
A phase retardance inspection instrument for inspecting a transparent substrate, comprising: a light source module for generating a single-wavelength light beam; a circularly polarized light generating module comprising a polarizer and a first phase retarder, wherein the single-wavelength light beam passes through the polarizer and the first phase retarder sequentially so as to generate a circularly polarized light after it is emitted into the circularly polarized light generating module; and a detecting module comprising a second phase retarder, a polarizing beam splitter, a first image sensor and a second image sensor, wherein an elliptically polarized light beam is generated by passing the circularly polarized light beam through the transparent substrate under inspection, the elliptically polarized light beam then passes through the second phase retarder and the polarizing beam splitter sequentially and enters the detecting module, and wherein the polarizing beam splitter splits the elliptically polarized light beam into intensity vector components of a left-hand circularly polarized light beam and a right-hand circularly polarized light beam, which are to be emitted into the first image sensor and the second image sensor, respectively.