Patent attributes
In general, in one aspect, the invention features assemblies that include a first polarizing beam splitter positioned in the paths of a pair of initial beams, the polarizing beam splitter being configured to combine the pair of initial beams to form an input beam. The assemblies further include an interferometer positioned to receive the input beam and configured to produce an output beam that includes information about an optical path difference between the paths of two component beams derived from the input beam. A second polarizing beam splitter is positioned in the path of the output beam and configured to split the output beam into a pair of secondary output beams that each include information about the optical path difference between the component beam paths.
