A wavefront sensor includes a light source (172) configured to illuminate a subject eye, a detector (122), a first beam deflecting element (112/412) configured to intercept a wavefront beam returned from a subject eye when the subject eye is illuminated by the light source (172) and configured to direct a portion of the wavefront from the subject eye through an aperture (118/418) toward the detector (122) and a controller, coupled to the light source (172) and the first beam deflecting element (112/412), configured to control the first beam deflecting element (112/412) to deflect and project different portions of an annular ring portion (444/494) of the wavefront from the subject eye through the aperture (118/418) and further configured to pulse the light source (172) at a firing rate to sample selected portions of the annular ring (118/418) at the detector.
