Four-channel polarimeter for time-resolved ellipsometry

A new four-channel partial polarimeter was designed for use in time-resolved ellipsometry measurements. The device outputs four parallel, equispaced beams from a single input beam. By detecting and digitizing the intensities of these four beams, the intensity, as well as two of the three elements of the reduced Stokes vector can be determined. Since there are no moving parts to the polarimeter, time resolution is limited only by the response time of the photodetectors and the digitizers. The linear array of output beams is ideal for streak-camera detection, yielding a potential time resolution of ~1 psec. A beam splitter is described that separates the input beam into two beams, which are parallel to the input beam and whose polarizations are nearly the same as the input beam. In addition, the polarimeter is achromatic, operating in the wavelength region from 220 to 1100 nm.