Method and apparatus for providing a gas correlation filter for remote sensing of atmospheric trace gases
US7050215B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 1, 2003 |
| Grant date | May 23, 2006 |
| Priority date | — |
| Expiry date | Aug 1, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J2003/1213
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A correlation filter is provided having passbands at wavelengths corresponding to the absorption spectrum of an atmospheric gas of interest. In particular, the correlation filter features narrow, non-linearly spaced passbands having center wavelengths that are correlated to the non-linearly spaced absorption lines of an atmospheric gas. A correlation filter in accordance with an embodiment of the present invention includes a compensation stack having a number of thin film layers, at least some of which have an optical thickness that is not equal to an integer multiple of one-quarter of a wavelength of an absorption line of the gas of interest. The correlation filter may be provided in association with an etalon, or may comprise a number of optical cavities. In accordance with an embodiment of the present invention, a number of absorption lines associated with an atmospheric gas may be simultaneously viewed, providing a signal indicating the presence and quantity of such gas in the atmosphere having a high signal-to-noise ratio.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.