Apparatus for laser-discharge imaging and focusing elements for use therewith
US5764274A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 16, 1996 |
| Grant date | Jun 9, 1998 |
| Priority date | — |
| Expiry date | Feb 16, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B6/4225
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A focusing assembly includes features that allow numerical aperture to be reduced and optimized by reducing aberrations and ghost reflections and easily controlling stop size, thereby increasing depth-of-focus. The assembly includes a single, bi-aspheric focusing lens that optimizes image quality at a specific off-axis field point. Passage of excessively divergent radiation is prevented by a baffle having a sharp, flared edge that minimizes reflection. A second aperture or baffle can be included to restrict high-divergence radiation emerging from the bi-aspheric focusing lens. All interior surfaces of the focusing assembly are preferably blackened, once again to minimize internal reflections.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.