Patent ID: 7251029

Claim:
A birefringence measurement apparatus for calculating information of polarization of light emitted from an object to be measured, said birefringence measurement apparatus comprising: a first polarization element for extracting a beam in a specific polarization direction of light emitted from a light source and directing the beam to the object; at least one beam splitting unit that splits the light emitted from the object into two beams having the same polarization as that of the light emitted from the object; at least two second polarization elements for extracting beams in a specific polarization direction of the light split by said beam splitting unit; at least two light-quantity detectors for detecting light quantity of beams that have transmitted through the second polarization elements; and an operation part for operating a light quantity received by said light-quantity detectors, wherein the beam splitting unit includes: a first plate inclining to the light emitted from the object, and splitting the light emitted from the object into a transmitted light and a reflected light; a second plate inclining to the reflected light from said first plate, and splitting the reflected light from said first plate into a transmitted light and a reflected light; and a third plate inclining to the transmitted light from said first plate, and splitting the transmitted light from said first plate into a transmitted light and a reflected light, wherein said second plate is arranged so that p-polarized component which has reflected upon said first plate reflects as s-polarized component on said second plate, said third plate is arranged so that p-polarized component which has transmitted through said first plate transmits as s-polarized component through said third plate, and the two beams having the same polarization as that of the light emitted from the object are the reflected light from said second plate and the transmitted light from said third plate.