Patent ID: 8462341

Claim:
An ellipsometer or polarimeter system comprising: a) a source of electromagnetic radiation; b) a polarizer; c) a stage for supporting a sample; d) an analyzer; and e) a detector; said ellipsometer or polarimeter system further comprising at least two rotating or rotatable compensator systems present at at least one location selected from the group consisting of: both between said source of electromagnetic radiation and said stage for supporting a sample; both between said stage for supporting a sample and said detector; and one thereof being between said source of electromagnetic radiation and said stage for supporting a sample, and the other thereof being between said stage for supporting a sample and said detector; said at least two rotating or rotatable compensators each comprising at least two sequential compensator elements oriented with respect to one another such that said entered electromagnetic beam undergoes internal reflection at least once in each of the elements, with the sequence, orientation, geometry, and symmetry of the elements being such that the locus of the output beam is substantially angularly undeviated from that of the input beam by a translation of the system, and the locus of the output beam angle is substantially angularly undeviated from that of the input beam by a rotation of the system about said beam locus; said ellipsometer or polarimeter system further comprising means for causing said each rotating or rotatable compensator to rotate at a desired rotation rate, which rate for one said compensator is the same as, or different than that of another thereof; and said ellipsometer or polarimeter system further comprising, for each compensator system, a containment system with provision for receiving selected compensator elements thereinto and orienting them in a desired relationship with respect to one another, and in which said selected elements are present.