Aberration Measurement Using Axial Intensity

Lateral (or transverse) information at either the exit pupil or the focal plane has been used in optical testing for quite some time[1]; however, aberrations can also be measured by using longitudinal intensity information. Geary and Peterson [2] showed that for an unobscured system, spherical aberration can be determined by taking an intensity scan along the optic axis near paraxial focus. In this paper, we describe how the same technique can be applied to systems containing a central obscuration and how the technique can be used to determine the location of paraxial focus. We also investigate the effects of coma and astigmatism. Experimental results demonstrate good agreement with theoretical predictions.