Apparatus for optically recording and reproducing information

An apparatus for optically reproducing and recording information comprising:

• a light source;
• an objective lens that focuses light beams emitted from the light source on an optical recording medium having tracks disposed at a track pitch, wherein the wavelength of the light beams emitted from the light source is greater than the track pitch of the optical recording medium;
• a wavefront splitting element that splits light beams reflected from the optical recording medium, wherein the wavefront splitting element includes a first region that receives mainly light beams generated by interference between zeroth-order diffracted beams and first-order diffracted beams among the light beams reflected from the tracks of the optical recording medium and a second region that receives substantially only the zeroth-order diffracted beams;
• a light detecting element that receives light beams passing through the wavefront splitting element;
• and
• a processor that generates focusing error signals using astigmatic focusing error detection on the basis of an output from the light detecting element that receives the light beams passing through the second region of the wavefront splitting element.

An apparatus for optically reproducing and recording information comprising:

• a light source;
• focusing means for focusing light beams emitted from the light source on an optical recording medium having tracks disposed at a track pitch, wherein the wavelength of the light beams emitted from the light source is greater than the track pitch of the optical recording medium;
• receiving means for receiving light beams reflected from the optical recording medium, wherein the receiving means includes a first region for receiving substantially only light beams generated by interference between zeroth-order diffracted beams and first-order diffracted beams among the light beams reflected from the tracks of the optical recording medium and a second region for receiving substantially only the zeroth-order diffracted beams;
• and
• generating means for generating focusing error signals using astigmatic focusing error detection on the basis of an output from the second region of said receiving means.