Abstract 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.
An apparatus for recording and reproducing optical information, comprising: a laser beam source for emitting a laser beam; a collimator lens in an optical path of said laser beam for collimating said beam to form a first parallel light beam; a prism arranged symmetrically with respect to an optical axis in an optical path of said first parallel light beam for changing said first parallel light beam to a second parallel light beam having a light intensity distribution in which a light intensity at a peripheral portion of said optical axis is greater than that at said optical axis; and an objective lens arranged in an optical path of said second parallel light beam for converging said second parallel light beam in the shape of a spot at a recording face of an optical information recording medium.
Claim 2
Independent Claim
137 words
An apparatus for recording and reproducing optical information, comprising: a laser beam source for emitting a laser beam; a collimator lens in an optical path of said laser beam for collimating said beam to form a first parallel light beam; a prism arranged symmetrically with respect to an optical axis in an optical path of said first parallel light beam for changing said first parallel light beam to a second parallel light beam having a light intensity distribution in which a light intensity at a peripheral portion of said optical axis is greater than that at said optical axis; and an objective lens arranged in an optical path of said second parallel light beam for converging said second parallel light beam in the shape of a spot at a recording face of an optical information recording medium.
Claim 3
Dependent Claim
16 words
An apparatus according to claim 1, in which said prism diverges said first parallel light beam.
Claim 4
Dependent Claim
24 words
An apparatus according to claim 2 in which said prism comprises an incident face and a light-emitting face which are parallel to each other.
Claim 5
Dependent Claim
16 words
An apparatus according to claim 1, in which said prism converges said first parallel light beam.
Claim 6
Dependent Claim
24 words
An apparatus according to claim 4 in which said prism comprises an incident face and a light-emitting face which are parallel to each other.
Claim 7
Dependent Claim
24 words
An apparatus according to claim 1 in which said prism comprises an incident face and a light-emitting face which are parallel to each other.