| 摘要 |
PROBLEM TO BE SOLVED: To maintain the uniformity of the illuminance regardless of the intensity unevenness and, further, reduce the interference noises. SOLUTION: A group of N×M 2-dimensional beams are generated from a beam emitted from a laser light source 1 by a 2-dimensional multibeam generating optical system 2 which consists of 1st and 2nd 1-dimensional multibeam generating optical systems 3 and 4. The group of N×M 2-dimensional beams are made to pass through fly-eye lens arrays 7a and 7b, condensor lenses 8a and 8b and a reticle 20. The 2-dimensional multibeam generating optical system 2 is constructed so as to have the light passage length difference between two arbitrary beams selected from the group of N×M beams not shorter than a coherence length determined by the time coherence of the laser light source 1 and the group of 2-dimensional beams are applied to the fly eye lens arrays 7a and 7b through one or a plurality of diffusion plates 5a and 5b. |
