A method and system is disclosed to aim a light beam at a retro-reflecting target such as an eye by emitting a probe beam through an Alvarez lens pair and detecting a retro-reflected glint on a focal plane array to determine the direction from which he glint is received and move a moving element of the Alvarez lens pair so as to point a light source directly at the retro-reflecting target. A ranging device may be incorporated to adjust the intensity of the light source.