Patent ID: 8049889

Claim:
A polarimeter comprising: an adjustable circular retarder that receives incoming light and rotates the polarization of the incoming light; a polarization beam splitter that polarizes the light received from the adjustable circular retarder by splitting the light into a first portion of light having a first polarization and a second portion of light having a second polarization, wherein the first portion of light is reflected by the polarization beam splitter along a first path and the second portion of light is transmitted through the polarization beam splitter along a second path; a first optical assembly that receives the first portion of light, rotates the polarization by substantially 90 degrees, and directs the first portion of light back to the polarization beam splitter along the first path such that the first portion of light is transmitted through the polarization beam splitter to a focal plane; and a second optical assembly that receives the second portion of light and selectively either (i) rotates the polarization by substantially 90 degrees and directs the second portion of light back to the polarization beam splitter along the second path such that the second portion of light with is reflected by the polarization beam splitter to the focal plane, or (ii) absorbs the second portion of light.