Hybrid shearing and phase-shifting point diffraction interferometer
US6573997B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 17, 2000 |
| Grant date | Jun 3, 2003 |
| Priority date | — |
| Expiry date | Feb 17, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B2290/50
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A new interferometry configuration combines the strengths of two existing interferometry methods, improving the quality and extending the dynamic range of both. On the same patterned mask, placed near the image-plane of an optical system under test, patterns for phase-shifting point diffraction interferometry and lateral shearing interferometry coexist. The former giving verifiable high accuracy for the measurement of nearly diffraction-limited optical systems. The latter enabling the measurement of optical systems with more than one wave of aberration in the system wavefront. The interferometry configuration is a hybrid shearing and point diffraction interferometer system for testing an optical element that is positioned along an optical path including: a source of electromagnetic energy in the optical path; a first beam splitter that is secured to a device that includes means for maneuvering the first beam splitter in a first position wherein the first beam splitter is in the optical path dividing light from the source into a reference beam and a test beam and in a second position wherein the first beam splitter is outside the optical path: a hybrid mask which includes a first se…
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