Optical element manufacturing method for projection illumination system for manufacturing of e.g. semiconductor components, involves tempering blanks, and tempering blanks in reduced atmosphere at temperature of seven hundred degree Celsius

摘要

The method involves tempering blanks (1) made from high-breaking material containing spinel, in oxygenic atmosphere (6a) in temperature (T1) of 1000 degree Celsius by a hot isostatic press (6). The blanks are tempered in reduced atmosphere at temperature of 700 degree Celsius, where the reduced atmosphere exhibits oxygen-portion of 50 ppm. The blanks are made from polycrystalline material as single crystal. The blanks are enclosed in a gas-tight capsule during during hot isostatic pressing. The blanks are tempered with ambient pressure. An independent claim is also included for a projection illumination system comprising a projection objective.