High numerical aperture catadioptric objectives without obscuration and applications thereof
US8259398B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 6, 2011 |
| Grant date | Sep 4, 2012 |
| Priority date | — |
| Expiry date | Oct 6, 2031 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S359/90
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Disclosed are high numerical (NA) catadioptric objectives without a central obscuration, and applications thereof. Such objectives can operate through a wide spectral bandwidth of radiation, including deep ultraviolet (DUV) radiation. Importantly, refractive elements in the catadioptric objectives can be manufactured from a single type of material (such as, for example, CaF2 and/or fused silica). In addition, the elements of such catadioptric objectives are rotationally symmetric about an optical axis. The catadioptric objectives eliminate the central obscuration by (1) using a polarized beamsplitter (which passes radiation of a first polarization and reflects radiation of a second polarization), and/or (2) using one or more folding mirrors to direct off-axis radiation into the pupil of the catadioptric objective. An example catadioptric objective is shown in FIG. 2.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.