Patent ID: 6470122
Filing Date: 2002-10-22
Classification: G02B

Abstract:
An optical coherence reduction method, comprising:providing a multimode light beam oscillated at plural different wavelengths; branching said multimode light beam into branched plural light beams each having a fixed optical path length difference therebetween; and forming said branched plural light beams into a single luminous flux or into collected luminous fluxes, wherein when a degree of coherence of said multimode light beam is expressed as a function of time, the degree of coherence has periodically spaced maximum value waveforms in which a full width at a half maximum of a first maximum value waveform is &tgr;t and a center-to-center distance between the first maximum value waveform and a second next adjacent maximum value waveform is &tgr;d, and the fixed optical path length difference L meets the following expression: c[(nâˆ’1)&tgr;d+&tgr;t/2]&lE;L&lE;c[n&tgr;d&tgr;t/2]wherein c denotes light velocity in a medium in which the light is propagated and n denotes an arbitrary natural number.