Neutral white-light filter device
US7230754B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Aug 13, 2004 |
| Grant date | Jun 12, 2007 |
| Priority date | — |
| Expiry date | Aug 13, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B5/122
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A substantially neutral filter across the white-light spectrum is obtained by minimizing the wavelength-dependent effects of filtering components and of reflective coatings on surfaces. The incoming light is captured by a first prism and directed toward the interface formed by the optical contact of a second prism with a face of the first prism, where the light is partially reflected internally and partially transmitted into the second prism. The reflected light is further reflected internally and directed toward the image surface out of the first prism. The fraction of light transmitted into the second prism is reflected back and redirected out of the system toward the incoming beam. The amount of energy directed toward the image plane is controlled by the judicious selection of the refractive indices in the two materials at the contacting interface of the first and second prisms. The second prism consists of a retro-reflector element adapted to reflect substantially all light transmitted at the interface with the first prism back along the optical path of the incoming beam.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.