Development of Illumination System for Detection of Small Particles with High Illuminance Using Laser Diode

Abstract

This paper discusses the optimum configuration of illumination system which detects small particles on a patterned specimen by illuminating a laser diode obliquely. A luminous part of laser diode spreads in a line. The real image of luminous part has to be projected with a rotational angle of θ around an optical axis of illumination. The angles of rotation and tilt asked for realizing the above mentioned condition are analyzed theoretically and experimentally. A new optical system with two cylindrical lenses is proposed and analyzed experimentally to reduce the width of illuminated area. Using this new optical system, the width is reduced to 1/2 - 1/3 compared with conventional optical system.