Optical properties restoration apparatus, the restoration method, and an optical system used in the apparatus
US7733563B2 · kind B2 · utility
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Key dates
| Filing date | Mar 6, 2007 |
| Grant date | Jun 8, 2010 |
| Priority date | — |
| Expiry date | Mar 6, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B1/14
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
An optical system has fluoride compounds provided in an environment exposed by vacuum ultraviolet light or plasma light, which has higher photon energy than an absorption wavelength of a base stock of the optical system. 1-layer of a protective film of SiO2 or metal oxides having a film thickness of 2-20 nm is formed at least on the light irradiation side (inner side) of the optical system to prevent the stripping of the fluorine atoms from the surface of the optical system. In addition, the protective film is a 1-layer film selected from one of SiO2, MgO, TiO2, or ZrO2.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.