| 摘要 |
PROBLEM TO BE SOLVED: To reduce the distortion of an illumination area when illumination light is radiated diagonally to the surface to be illuminated and improve the efficiency of light utilization.SOLUTION: An illumination optical system includes a first optical system α for reshaping a beam from a light source 1 so that the cross sectional shape of the beam becomes closer to rectangular shape of a surface 6 to be illuminated, and a second optical system &bgr; for guiding a beam from the first optical system to the surface to be illuminated and having an optical axis RA tilted to the normal line N of the surface to be illuminated. The illumination optical system includes a translucent element having a light incident plane and a light emission plane whose angles of inclination &thetas;,&thetas;to the optical axis of the second optical system in a plane that includes the optical axis of the second optical system and the normal line of the surface to be illuminated are mutually different. The translucent element is place between the first optical system and the surface to be illuminated. |
