Light measurement apparatus and light measurement method

Abstract

A light measurement apparatus includes a polarizing optical element, an orthogonal separating section, a light reception section, a rotation control section and a polarization state measuring section. The polarizing optical element converts detection light to linearly polarized light. The orthogonal separating section orthogonally separates the linearly polarized light into orthogonally separated lights. The light reception section receives the orthogonally separated lights. The rotation control section rotates the polarizing optical element so that a rotation axis extends along an optical path of the detection light. The polarization state measuring section measures a polarization state of the detection light using intensities of the orthogonally separated lights.

What is claimed is: 
     
         1 . A light measurement apparatus comprising:
 a polarizing optical element which converts detection light to linearly polarized light;   an orthogonal separating section which orthogonally separates the linearly polarized light into orthogonally separated lights;   a light reception section which receives the orthogonally separated lights;   a rotation control section which rotates the polarizing optical element so that a rotation axis extends along an optical path of the detection light; and   a polarization state measuring section which measures a polarization state of the detection light using intensities of the orthogonally separated lights.   
     
     
         2 . The light measurement apparatus according to  claim 1 , wherein
 the rotation control section rotates the polarizing optical element within a predetermined angular range.   
     
     
         3 . The light measurement apparatus according to  claim 1 , wherein
 the polarization state measuring section has a vibration locus determining section which determines a vibration locus of the detection light using the intensities of the orthogonally separated lights and measures the polarization state of the detection light using the vibration locus.   
     
     
         4 . The light measurement apparatus according to  claim 1 , wherein
 the polarization state measuring section measures the polarization state by assuming the detection light to be elliptically polarized light and by using the feature values of the elliptically polarized light.   
     
     
         5 . The light measurement apparatus according to  claim 1 , wherein
 the polarizing optical element has a Glan-Thompson prism.   
     
     
         6 . The light measurement apparatus according to  claim 1 , wherein
 the orthogonally separating section has a Wollaston prism.   
     
     
         7 . A light measuring method, which is a method for measuring the polarization state of detection light by controlling an optical apparatus provided with a polarizing optical element which converts the detection light to linearly polarized light, an orthogonal separating section which orthogonally separates the linearly polarized light into orthogonally separated lights, and a light reception section which receives the orthogonally separated lights, the method comprising:
 rotating the polarizing optical element so that a rotation axis extends along an optical path of the detection light; and   measuring the polarization state of the detection light using intensities of the orthogonally separated lights.