Direct ray aberration estimation in Hartmanngrams by use of a regularized phase-tracking system

The Hartmann test is a well-known technique for testing large telescope mir rors. The Hartmann technique samples the wave front under analysis by use o f a screen of uniformly spaced array of holes located at the pupil plane. T he traditional technique used to gather quantitative data requires the meas urement of the centroid of these holes as imaged near the paraxial focus. T he deviation from its unaberrated uniform position is proportional to the s lope of the wave-front asphericity. The centroid estimation is normally don e manually with the aid of a microscope or a densitometer; however, newer a utomatic fringe-processing techniques that use the synchronous detection te chnique or the Fourier phase-estimation method may also be used. Here we pr opose a new technique based on a regularized phase-tracking (RPT) system to detect the transverse aberration in Hartmanngrams in a direct way. That is , it takes the dotted pattern of the Hartmanngram as input, and as output t he RPT system gives the unwrapped transverse ray aberration in just one ste p. Our RPT is compared with the synchronous and the Fourier methods, which may be regarded as its closest competitors. (C) 1999 Optical Society of Ame rica OCIS codes: 100.5070, 120.5050, 220.4840.