Reflective waveplates for pupil polarization filtering
US12322620B2 · kind B2 · utility
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3References
21Claims
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Key dates
| Filing date | May 31, 2022 |
| Grant date | Jun 3, 2025 |
| Priority date | — |
| Expiry date | Oct 23, 2042 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/8848
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical inspection system includes one or more gratings to convert the polarization of light scattered from a target from an elliptical polarization that varies spatially across a collection pupil to a linear polarization that is uniformly oriented across the collection pupil. The one or more gratings have phase retardation that varies spatially across the collection pupil in accordance with the elliptical polarization. The one or more gratings include at least one grating on a reflective substrate. The optical inspection system also includes a linear polarizer to filter out the linearly polarized light.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.