| 摘要 |
<p>An optical information recording and reproducing apparatus is provided with an optical unit for recording or reproducing information at a plurality of positions in the thickness direction of an optical recording medium. The optical unit is provided with a light source, objective lenses, and variable focusing lenses and apertures. Here, the light source is for emitting light. The objective lenses are for collecting light emitted from the light source into the optical recording medium to form a light collected spot. The variable focusing lenses and apertures are provided respectively between the light source and the objective lenses. The optical information recording and reproducing apparatus is moreover provided with a light source drive circuit and a variable focusing lens drive circuit. Here, the light source drive circuit is for driving the light source. The variable focusing lens drive circuit is for driving the variable focusing lenses to move the positions of the light collected spot in the thickness direction of the optical recording medium. The positions of the main surfaces of the variable focusing lenses and the position of surfaces including the aperture coincide with the positions of the front focal surfaces of the objective lenses or the positions of surfaces optically conjugate therewith.</p> |
