APODIZED MICRO-LENSES FOR HARTMANN WAVEFRONT SENSING

摘要

One of the fundamental sensitivity limits of Hartmann-type wavefront sensors, especially for coherent light, is the crosstalk between adjacent lenses caused by the hard-edge diffraction from the lens apertures. In this paper we describe the use of lens apodization to reduce the hard-edge diffraction and thus reduce the crosstalk between lenses. First, diffraction modeling of the crosstalk reduction between classic square aperture diffraction and gaussian diffraction is presented. We present a new technique for apodization of micro-lenses based upon evaporation of a metal through a micromachined array of apertures. A one-dimensional trace through the apodization aperture was shown to fit well to a 3rd order super-gaussian profile. Finally, the intensity profiles from unapodized and apodized lenses are presented showing no hard-edge ringing with apodization when observed on a CCD.