External pupil lens system
US6563654B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 12, 2001 |
| Grant date | May 13, 2003 |
| Priority date | — |
| Expiry date | Apr 26, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B27/0037
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An external pupil lens system (200) with an entrance pupil distance at least three times that of the effective focal length. The lens system is comprised of several conventional lenses and a diffractive optical element (DOE) for secondary chromatic aberration correction. In the illustrative embodiment, the system includes an entrance pupil (50), followed by a lens group (52) containing two refractive elements for primary color correction. Next along the optical axis is lens group (54), which contains two refractive elements for astigmatism and higher order coma correction, followed by lens group (60), which contains one refractive element (62) and one DOE (64) for secondary color correction.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.