Laser radar device
US5267010A · kind A · utility
Inventors
Key dates
| Filing date | May 31, 1991 |
| Grant date | Nov 30, 1993 |
| Priority date | — |
| Expiry date | May 31, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02A90/10
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A laser radar system capable of measuring windspeed to within 1 m/s at distances in the range of 10 km. The system comprises two Faraday atomic line filter/detectors combinations, a first filter-detector which consist of a metal vapor cell located between crossed polarizers. A magnetic field is applied to the cell which Zeeman splits the energy levels resulting in different absorption lines for left and right circularly polarized light. Near these lines the filter acts as a Faraday rotator providing rotary power only in the vicinity of an absorption line, which provides the 90 degree rotation necessary to pass the second polarizer. At higher fields and vapor densities multiple rotations lead to rapid modulations in the transmission spectrum. Away from the absorption line the filter provides an out of band rejection that is determined by the extinction ratio of the crossed polarizers. By tuning the temperature and the magnetic field in each Faraday filter sharply crossing response curves can be produced. A preferred lasing frequency range is a frequency range covering a portion of one of the slopes of the peak of the first filter and a portion of one of the opposite direction slopes…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.