Recording and reproducing optical information device which converts the first beam into a second beam having different light intensity distribution

摘要

An apparatus for recording and reproducing optical information comprises a laser beam source for emitting a laser beam; a collimator lens for forming light emitted from the laser beam source as an approximately parallel light beam; an objective lens for converging the approximately parallel light beam from the collimator lens in the shape of a spot on a recording face of an optical information recording medium; a device for recording and reproducing the optical information by converging the laser beam in the shape of a spot by the objective lens on the recording face of the optical information recording medium; a prism symmetrically arranged with respect to an optical axis in an optical path from the collimator lens to the objective lens; and a device for making a parallel light beam from the collimator lens through the prism incident to the objective lens so as to provide a light intensity distribution in which the light intensity in a peripheral portion of the optical axis is larger than that on the optical axis.