Patent ID: 7239388
Filing Date: 2007-07-03
Classification: G01J,G01N

Abstract:
1. An apparatus for measuring retardance in a sample, comprising: a sample chamber for receiving the sample; a source of illumination light; optics for directing the illumination light toward the sample; a detector for measuring an intensity of light incident on the detector; optics for directing light that has interacted with the sample toward the detector; a first polarizer for selectively transmitting light that is substantially circularly polarized; a second polarizer for selectively transmitting light that has one of a selected elliptical polarization state and a circular polarization state; a controller for varying the polarization state of the second polarizer to correspond to a plural number of states χ a processor connected to the detector for determining the sample retardance from the measured incident light intensity obtained when the second polarizer is set to each of the states χ wherein the number of states is five, and wherein one of the states χ