An approach to in-situ wavefront aberration measurement is explored. The test is applicable to sensing aberrations from the image plane of a microlithography projection system or a mask inspection tool. A set of example results is presented which indicate that the method performs well on lenses with a Strehl ratio above 0.97. The method uses patterns produced by an open phase figure1 to determine the deviation of the target image from its ideal shape due to aberrations. A numerical solution in the form of Zernike polynomial coefficients is reached by modeling the object interaction with aberrated pupil function using the nonlinear optimization routine over the possible deformations to give an accurate account of the image detail in 2-D. The numerical accuracy for the example below indicated superb performance of the chosen target shapes with only a single illumination setup.

Date of creation, presentation, or exhibit



Proceedings of the SPIE Conference on Optical Microlithography XVIII, vol. 5754, pp. 1728-1737, 2005 Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type

Conference Proceeding

Department, Program, or Center

Microelectronic Engineering (KGCOE)


RIT – Main Campus