Experimental results for expanding the dynamic range of a Shack-Hartmann sensor using astigmatic microlenses

A conventional Shack-Hartmann wavefront sensor cannot be used for the measurement of wavefronts with steep slopes if the spots leave their respective subapertures. In an earlier paper [N. Lindlein, J. Pfund, and J. Schwider, ''Expansion of the dynamic range of a Shack- Hartmann sensor by using astigmatic microlenses, Opt. Eng. 39(8), 2220-2225 (2000)], we described a method to expand the dynamic range of a Shack-Hartmann wavefront sensor by marking the spots using astigmatic microlenses. We present experimental results for this method and describe how this special sensor can be interpreted as a combination of several Shack-Hartmann sensors with enlarged subapertures.