An illuminating optical device comprises a light source for supplying light, and a condenser lens system for collecting the light from the light source and guiding the light onto an object to be illuminated. The condenser lens system has an optical element that has a refractive power, and that can be...http://www.google.com/patents/US6127095?utm_source=gb-gplus-sharePatent US6127095 - Illuminating optical device and semiconductor device manufacturing method
