| 摘要 |
PCT No. PCT/GB87/00050 Sec. 371 Date Nov. 12, 1987 Sec. 102(e) Date Nov. 12, 1987 PCT Filed Jan. 27, 1987 PCT Pub. No. WO87/04529 PCT Pub. Date Jul. 30, 1987.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.
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