1. An ophthalmic instrument comprising: a wavefront sensing illumination source producing light that is formed as a spot image on the retina of the human eye and reflected there from; and a wavefront sensor that estimates aberrations in reflections of the light formed as a spot image on the retina of the human eye, wherein the wavefront sensor comprises a beam splitter operably disposed between a lenslet array and multiple imaging devices, said lenslet array forming a first array of spots, and said multiple imaging devices capturing multiple images of said first array of spots for use in estimating said aberrations.