Impact of uneven pupil irradiance on Hartmann Shack measurements

Neglecting pupil irradiance fluctuations using a Hartmann Shack wavefront sensor leads to phase reconstruction bias. This bias depends on the pupil irradiance profile, the Hartmann Shack geometry and the amplitude and structure of the aberrations. In order to quantify the impact on real eye aberrations measurement, pupil irradiance and ocular aberrations of three trained subjects have been acquired on the LESIA testbed at Hospital des Quinze-Vingts. The pure WFS error is quantified with these data sets, on various lenslet array geometries. The propagation of this pure WFS error on actual systems, namely a static aberro- meter and an AO imager, is addressed. We find that, for a large enough lenslet array and with a reasonably clean optical path, the induced error is negligible.