Back to results
US 6,201,609 B1Granted
Interferometers utilizing polarization preserving optical systems
AssigneeZygo Corporation
InventorsHenry Allen Hill, Peter J. de Groot
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeZygo Corporation
InventorsHenry Allen Hill, Peter J. de Groot
Estimating the term…
Interferometers utilizing polarization preserving optical systems by plane polarized beams are deviated through preselected angles without changing their linear state of polarization. The interferometers utilizing such optical systems have a variety of applications and are particularly suitable for use in the field of distance measuring interferometry (DMI) to enhance measurement accuracy by reducing undesirable polarization effects that can introduce errors associated with an otherwise present undesirable polarization rotation found in classical retroreflectors. Prismatic optical elements are preferably used to construct assemblies which can include polarization beam splitting coating arrangements and/or birefringent materials to enhance the extinction ratio between orthogonally polarized beams propagating through such systems.
Polarization interferometric apparatus, said apparatus comprising interferometer means for receiving at least two beams having orthogonal states of polarization and providing first and second interferometer legs, separating said two beams for travel along said first and second interferometer legs, respectively, and generating exit beams containing information about the respective differences in the optical paths each beam experienced in traveling said first and second interferometer legs, said first and second interferometer legs having optical paths structured and arranged such that at least one of them has a variable physical length, the optical path length difference between said first and second interferometer legs varying in accordance with the difference between the respective physical lengths of their optical paths and wherein at least one of said first and second interferometer legs comprises a polarization preserving optical system structured and arranged to deviate plane polarized beams through preselected angles while maintaining their linear polarization as they travel along said at least one of said first and second interferometer legs.
Polarization interferometric apparatus, said apparatus comprising interferometer means for receiving at least two beams having orthogonal states of polarization and providing first and second interferometer legs, separating said two beams for travel along said first and second interferometer legs, respectively, and generating exit beams containing information about the respective differences in the optical paths each beam experienced in traveling said first and second interferometer legs, said first and second interferometer legs having optical paths structured and arranged such that at least one of them has a variable physical length, the optical path length difference between said first and second interferometer legs varying in accordance with the difference between the respective physical lengths of their optical paths, said interferometer means further including a Polarization preserving optical system located in at least one of said first and second interferometer legs and structured and arranged to deviate plane polarized beams through preselected angles while maintaining their linear polarization as they travel along said at least one of said first and second interferometer legs and a plurality of differently tilted retardation elements to reduce the effects of ghost beams on exit beams.
Dependencies are inferred from the claim text.