Patent ID: 6934023

Claim:
A method of polarimetry by allowing a light with a known polarization direction “X” to be incident upon a sample, detecting a polarization direction of a light transmitted through said sample, and measuring an angle of rotation of a polarization direction in said sample on the basis of the difference between said polarization directions of said incident light and said transmitted light, said method further comprising the steps of: changing and modulating said polarization direction “X” of said incident light; detecting only a polarized component in a specific direction out of said light transmitted through said sample by a photosensor to obtain an output signal; performing a phase sensitive detection on said output signal by using a signal for said modulating as a reference signal to obtain a demodulation signal “Y”; calculating an angle of rotation from 3 or more measuring points “Pi” (Xi, Yi) obtained from 3 or more polarization signals “Xi”, where i denotes an integer of from 1 to n, where n denotes 3 or more, discretely selected from said polarization direction “X”, and 3 or more demodulation signals “Yi”, where i denotes an integer of from 1 to n and n denotes 3 or more, respectively corresponding to said polarization signals Xi; and measuring repeatedly at least one measuring point “Pi” out of said 3 or more measuring points “Pi” (Xi, Yi) when said calculated angle of rotation is judged not effective, to calculate again said angle of rotation on the basis of said measuring point “Pi” (Xi, Yi) measured repeatedly, and repeating said measurement until said angle of rotation is judged effective.