Speckle resistant method and apparatus with chirped laser beam
US5434662A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 23, 1993 |
| Grant date | Jul 18, 1995 |
| Priority date | — |
| Expiry date | Dec 23, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S17/26
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Laser beam speckle effects are mitigated by frequency chirping a single-mode laser beam, reflecting it off a speckling surface, and then integrating the reflected beam over at least one chirp period. The speckle reduction is comparable to the use of a multi-longitudinal mode beam having a bandwidth similar to the chirped frequency excursion, while leaving the beam compatible with nonlinear optical processes that are not compatible with multi-longitudinal mode beams. Where the nonlinear process is stimulated Brillouin scattering (SBS) phase conjugation, the beam can be chirped at a rate up to the order of ##EQU1## where .DELTA..nu..sub.B is the gain bandwidth and L is the effective SBS interaction length of the phase conjugator, and C is the speed of light. Other nonlinear processes with which the beam may be used include harmonic generation and Raman-based beam cleanup or wavelength conversion.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.