Testing aspheric in interferometric setups: removal of a ustment errors from measurement result

We demonstrate experimentally a valid method to remove the adjustment errors from wavefront aberration in interferometric setups when measuring convex aspheric surface with asymmetric errors. By comparing the coefficients of Zernike polynomials of the first measurement with that of the second measurement after rotating the aspheric to 180degrees, we can decide whether there are adjustment errors in measured wavefront and remove them. We have successfully tested a 100-mm diameter convex surface of errors 234 nm P-V after removing adjustment errors. It is believed that the method may greatly improve the measurement accuracy, and simplify the adjustment of the interferometric setups for an aspheric surface with strong asymmetric errors. (C) 2004 Elsevier B.V. All rights reserved.