| 摘要 |
PROBLEM TO BE SOLVED: To minimize the illuminance irregularity and project a pattern with high resolution by providing a rotatable optical element on which coating whose transmissivity varies with the angle of incidence is applied and whose angle to an optical axis changes, in the vicinity of a secondary light source, and rotating this optical element thereby adjusting the illumination irregularity on the plane of an object. SOLUTION: An optical integrator 6 constitutes a fly-eye lens, having a plurality of microlenses arranged at specified pitches two-dimensionally along the plane crossing the optical axis at right angles, and forms a secondary light source in the vicinity of the light emission face 6b. Then, an illumination irregularity correcting board 17 consists of an optical element where coating whose transmissivity or spectral transmissivity changes depending upon the angle of incidence is applied on a transparent board. The illumination irregularity correcting board 17 is retained by the holder 18 inclined by a specified angle to the optical axis La. Moreover, the holder 18 can rotate to the optical axis La. Hereby, the angle of incidence of the luminous flux into the illumination irregularity correcting board 17 is changed, whereby the illumination irregularity on the face for irradiation is adjusted. |
