| 摘要 |
To sufficiently reduce coherence without applying optical path length difference exceeding coherence length between branched light beams when the coherence of a coherent beam is reduced, a multimode laser beam oscillated at plural different wavelengths is branched into plural, such fixed optical path length difference L as meets the following expression 1 is applied between the plural branched multimode laser beams and the above plural multimode laser beams are arranged on the same surface. <MATH> (However, in the above expression 1, c denotes light velocity in a medium in which light is propagated and n denotes an arbitrary natural number.) <IMAGE> |
