Analysis on error and tolerance for the wavefront reference source of point diffraction interferometer

Abstract

To keep the advantages of fiber point diffraction interferometer which is easy to align and control the diffracted light,we design a new wavefront reference source( WRS). WRS can keep the advantages of fiber point diffraction interferometer and pin-hole point diffraction interferometer,and it also can be used to test the wavefront aberration of larger NA optical system for Extreme Ultraviolet Lithography( EUVL). The analysis of error for this new WRS and calibration of the system error is very important for realizing a more accurate test of wavefront aberration. Based on the analysis of various errors,we study the calibration algorithm in detail,and obtain the tolerance of several WRS important components including that the angle tolerance of rotation stage is0. 5° and the deviation factor is 0. 5% when rotation is away optical axis.