Super-resolution optical head apparatus

A super-resolution optical head apparatus, comprising:

• a coherent light source for emitting a coherent beam;
• a polarizing phase plate for separating the coherent beam emitted from said coherent light source into a primary beam and a subsidiary beam which has a plane of polarization perpendicular to a plane of polarization of said primary beam and an intensity distribution in which peak values are placed at least on both sides of a center of said primary beam and a principal portion thereof is equal, or almost equal, in size to a principal portion of said primary beam and emitting them;
• a focusing means for superimposing the primary beam and subsidiary beam emitted from said polarizing phase plate upon each other and focusing them onto an information storage surface having an optical information storage carrier;
• a control means for controlling said focusing means such that a light beam composed of said primary beam and said subsidiary beam being superimposed upon each other performs focusing and tracking with respect to the optical information storage carrier of said information storage surface;
• a holographic optical element provided integrally with said focusing means, said holographic optical element diffracting the light beam in a return trip reflected from said information storage surface and introducing the diffracted light beam onto a plane substantially flush with a light emitting surface of said coherent light source:
• a polarization separating means for receiving the light beam in the return trip which has been diffracted by said holographic optical element and separating said light beam in the return trip into the primary beam and the subsidiary beam through polarization separation;
• an optical detecting means provided on the plane substantially flush with the light emitting surface of said coherent light source, said optical detecting means individually detecting respective intensities of the primary beam and subsidiary beam emitted from said polarization separating means and outputting a light intensity signal;
• and
• a calculating means for calculating, based on the light intensity signal outputted from said optical detecting means, a super-resolution scanning signal and outputting it.