Short-wavelength infrared (SWIR) multi-conjugate liquid crystal tunable filter
US9256013B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 15, 2013 |
| Grant date | Feb 9, 2016 |
| Priority date | — |
| Expiry date | Dec 30, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F1/13473
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A SWIR hyperspectral imaging filter has serial stages along an optical signal path with angularly distributed birefringent retarders and polarizers. The retarders can include active retarders such as tunable liquid crystal birefringent elements, passive retarders such as fixed retarders, and/or combinations thereof. Distinctly different periodic transmission spectra are provided by different filter stages, each having multiple retarders, in particular with some stages having broad bandpass peaks at wide spectral spacing and other stages have very narrow closely spaced peaks. The respective spectra include at least one tunably selectable band at which the transmission spectra of the filter stages coincide, whereby the salutary narrow bandpass and wide spectral spacing ranges of different stages apply together, resulting in a high finesse wavelength filter suitable for spectral imaging. The filter may be configured to provide faster switching speed and increased angle of acceptance and may operate in the rage of approximately 850-1700 nm.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.