| 摘要 |
PURPOSE:To execute the high-brightness illumination with excellent uniformity and without a speckle by a method wherein a means, to differentiate light paths, which is composed of a total reflector and a partial reflector which are installed to be parallel with each other and to be face to,face with each other is arranged between a coherent light source and a secondary light-source formation part to form two or more secondary light-sources. CONSTITUTION:An optical device illumination for is composed of the following: a narrow-band oscillating excimer laser light source 1 which outputs a coherent laser beam; a repetitive reflector 2 which produces, from said laser beam, a bundle of light beams having mutually differentiated light paths; an integrator 4 which forms two or more secondary light sources (images) 3 near the exit face while the position of image formation is being shifted synchronously with oscillating pulses of said laser beam; the laser beam illuminates the surface of a reticle 6. At the repetitive mirror 2 both faces of a quartz substrate 25 are coated with a total reflector face 2C and a partial reflector face 2R; the mirror is arranged in such a way that its normal line is tilted to be ALPHA=150 deg. with reference to the incident direction of the laser beam L. Through the repetitive mirror 2 and the integrator 4, which is equipped with a shifting means, the coherence is reduced at two stages. |
