Precision method for evaluating primary aberrations of lenses with a Twyman interferometer

Abstract

A simplified procedure for separat e evaluation of the three prim ary aberra tions of lenses wit h the Twyman le ns tes ting inte rfe romet e r is described. Eac h of the aberra tion coeffi cien ts is found to be a fun ction of observations at only four points on the lens . Equations a re give n for the optimum c hoice of refere nce points that give best res ult s. These equations are applied to dat a pre vi ously re ported in the lite ra ture. The results indicate that thi s procedure is suffi cie ntl y precise to reveal high orde r aberrations in a lens th at was assumed to be practically free from suc h a be rrations.