Optical system with improved durability for projection exposure apparatus and method for manufacturing optical system for projection exposure apparatus

摘要

An optical system is provided in a projection exposure apparatus for processing an excimer laser beam. The optical system includes at least one optical member made of silica glass having a chlorine concentration of about 1 ppm or less, and at least one optical member made of silica glass having a chlorine concentration of about 1 ppm to about 200 ppm.