Securing optical element holders together using screws, for projection lenses in microlithography, by measuring region of holder surface using interferometric measuring device, and varying torque to achieve uniform interference pattern

摘要

The method involves using two or more screws. A reference region of the holder surface associated with one (10) of the screws is measured directly after screwing using an interferometric measuring device (12). The torque applied to the respective screw is varied based on the interferometric measurement data, so that a uniform interference pattern is produced. An Independent claim is included for a projection exposure system.