Deviation angle self compensating substantially achromatic retarder
AssigneeJ.A. Woollam Co., Inc.
InventorsBlaine D. Johs, Steven E. Green, Craig M. Herzinger, Duane E. Meyer
Life of this patent
Estimating the term…
Abstract
A substantially achromatic multiple element compensator system for use in wide spectral range (for example, 190-1700 nm) rotating compensator spectroscopic ellipsometer and/or polarimeter systems. Multiple total internal reflections enter retardance into an entered beam of electromagnetic radiation, and the elements are oriented to minimize changes in the net retardance vs. the input beam angle resulting from changes in the position and/or rotation of the system of elements.
Claims21
A system for introducing a relative phase retardation into orthogonally polarized components of an electromagnetic beam entered thereinto, said system consisting of at least two sequential elements oriented with respect to one another such that said entered electromagnetic beam undergoes total internal reflection at least once in each of the at least two elements;
- the sequence, orientation, geometry, and symmetry of the elements being such that the output beam position is substantially undeviated by a translation of the system, and the output beam angle is substantially undeviated by a rotation of the system;
- said system being further characterized by at least one selection made from the group consisting of:
- at least one of the sequential elements has a mechanism for translating and/or tilting the element, for the purpose of aligning the system such that the output beam is substantially undeviated from said input beam;
- at least one of the sequential elements has a coating upon a surface thereof at which internal reflection of a beam of electromagnetic radiation occurs, said coating having a different refractive index than does the material from which said corresponding element is comprised;
- at least one of the sequential elements has a coating upon a surface thereof through which a beam of electromagnetic radiation enters or exist, said coating having a different refractive index than does the material from which said corresponding element is comprised;
- there is present an additional sequential multiple wedge system in said system for introducing a relative phase retardation into orthogonally polarized components of an electromagnetic beam, wherein one said wedge can be rotated with respect to another thereof and/or both wedge can be rotated simultaneously, for the purpose of aligning the system such that the output beam is substantially undeviated from said input beam.
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 one rotatable compensator system present at at least one location selected from the group consisting of:
- between said source of electromagnetic radiation and said stage for supporting a sample;
- and
- between said stage for supporting a sample and said detector;
- said at least one rotatable compensator comprising at least two sequential elements oriented with respect to one another such that said entered electromagnetic beam undergoes total 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 undeviated from that of the input beam by a translation of the system, and the locus of the output beam angle is substantially undeviated from that of the input beam by a rotation of the system;
- said ellipsometer being characterized in that at least one element of said at least two sequential elements of said at least one rotatable compensator has a coating on at least one surface thereof which has a different refractive index from that of the material of said element.
A method of providing a compensator system comprising at least two sequential elements oriented with respect to one another such that an entered electromagnetic beam undergoes total 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 output beam from said system is substantially undeviated from that of the input beam by a translation of the system, and the locus of the output beam angle is substantially undeviated from that of the input beam by a rotation of the system;
- said method comprising the steps of:
- a) providing a system comprising at least two sequential elements oriented with respect to one another such that entered electromagnetic beam undergoes total internal reflection at least once in each of the elements, at least one of said elements being mounted to allow translation and/or rotation thereof with respect to another of said elements;
- at least one of said at least two sequential elements having a coating on at least one surface thereof, which coating has a different refractive index from that of the material from which said comprises said element;
- b) causing a beam of electromagnetic radiation to enter and exit from said sequence of elements;
- c) effecting translation and/or rotation of said element which is mounted to allow translation and/or rotation thereof with respect to another of said elements such that translation and/or rotation of said system causes reduced deviation of the locus of said exiting beam as compared to that of said input beam.
Dependencies are inferred from the claim text.