Reducing phase fluctuations in a coherent radiation beam using feedforward control
US4847477A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 12, 1987 |
| Grant date | Jul 11, 1989 |
| Priority date | — |
| Expiry date | Nov 12, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F2/00
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method and apparatus for reducing fluctuations such as phase noise in a characteristic of a coherent beam of radiation. The apparatus includes an interferometer for sensing the fluctuation at the first position to generate an interference beam. The interference beam is incident on a radiation detector such as a photodiode which generates an electrical output signal responsive to the intensity of the incident beam. This signal is amplified by an amplifier and fed to a phase modulator. Another portion of the original laser beam is also fed to the phase modulator. The arrangement is such that the phase modulations applied to the beam by the phase modulator under the control of the signal from the detector reduce or cancel the phase noise in the original beam.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.