Anamorphic achromatic prism for optical disk heads

摘要

A multi-element, air-spaced prism system for use in a reflective-type optical media device having a light source to provide an incident light beam provides an achromatic, anamorphic prism which corrects for astigmatism and ellipticity in the light beam from the light source. One embodiment of the prism system provides at least two reflections of a return beam from the reflective-type optical media. The return prism provides these reflections from various optical surfaces in the multi-element prism system. In one embodiment, the prism system also provides a reflection of a portion of the incident beam. This reflection is directed to a detector which can, for instance, monitor the intensity of the light beam.