Tracking system with excited state atomic line filter
US7821624B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 5, 2006 |
| Grant date | Oct 26, 2010 |
| Priority date | — |
| Expiry date | Aug 29, 2028 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S5/06837
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A tracking system utilizing an excited state atomic line filter. The filter includes a metal vapor cell having an optical entrance port and an optical exit port and containing a metal vapor having a first excited energy state with a resonant frequency, and a second excited energy state. The cell has an absorption line, at or near a desired filter wavelength. The platform to be tracked, which could be an un-manned aerial vehicle has a beacon laser system located on it for producing a beacon laser beam at a wavelength within the narrow spectral band. The present invention solves the problem of lack of ground state resonant lines in at wavelengths substantially longer than those of visible light. Atomic line filters of the Faraday or Voigt crossed polarizer type are provided in which alkali metal atomic vapor in a vapor cell is excited with a pump beam to an intermediate excited state where a resonant absorption line, at a desired wavelength, is available. A magnetic field is applied to the cell producing a polarization rotation for polarized light at wavelengths near the resonant absorption lines. Thus, all light is blocked by the cross polarizers except light near one of the spaced …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.