Patent ID: 7277186
Filing Date: 2007-10-02
Classification: G01J

Abstract:
1. A method for the interferometric measurement of non-rotationally symmetric wavefront components of order u*2 k with k being a natural number including zero and u being a natural odd number on a specimen brought into two rotational positions, at least one measurement result being determined in both rotational positions, whereas in a first step a measurement is taken in a first rotational position, whereupon in a second step the specimen is rotated by 360/2 (k+1) degrees and measured, whereas the difference of both measurements is divided by 2 and averaged with (2 k −1) data maps, obtained by rotating the same difference computationally by 1 *360/2 k , 2*360/2 k , . . . , (2 k −1)*360/2 k degrees with the average result containing all non rotational wavefront components of the specimen with orders u*2 k .