Filter with preselected attenuation/wavelength characteristic
US5583689A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 8, 1995 |
| Grant date | Dec 10, 1996 |
| Priority date | — |
| Expiry date | Feb 8, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S2301/04
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A filter has a preselected attenuation/wavelength characteristic, in which spatially separated parts of the filter attenuate different wavelengths. The spatially-separated parts have different attenuation characteristics to attenuate different wavelengths in a predetermined manner to provide a selected attenuation/wavelength characteristic. In one arrangement an interference type filter includes a grating, the pitch of which varies spatially. In one instance, the structure to determine the proportion of radiation subject to interference includes a grating of spatially-varying effectiveness, but alternatively it may include an attenuation filter, the attenuation effect of the attenuation layer varying spatially. In another arrangement, the filter may include structure to separate received radiation into a spatially-disposed spectrum, and to attenuate different parts of the spatially-disposed spectrum in such a manner as to provide the selected attenuation/wavelength characteristic.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.