Multi-conjugate liquid crystal tunable filter
US6992809B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 2, 2005 |
| Grant date | Jan 31, 2006 |
| Priority date | — |
| Expiry date | Feb 2, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F2203/055
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A hyper-spectral imaging filter has serial stages along an optical signal path in a Solc filter configuration. Angularly distributed retarder elements of equal birefringence are stacked in each stage, with a polarizer between stages. The retarders can include tunable (such as abutted liquid crystals tuned in unison), fixed and/or combined tunable and fixed birefringences. Although the retardations are equal within each stage, distinctly different retardations are used for two or more different stages. This causes some stages to pass narrow bandpass peaks and other stages to have widely spaced bandpass peaks. The transmission functions of the serial stages are superimposed with selected preferably-tunable peaks coinciding. The resulting conjugate filter has a high finesse ratio, and good out of band rejection.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.