| 摘要 |
<p>There is provided an apparatus for optical recording, reproducing and erasing data into or from a recording medium, comprising an optical head (4), and a sensor (3) for sensing a thickness of a recording medium (1), characterized by a focal distance compensator (7) for varying a focal distance of the light in accordance with a thickness of the recording medium (1). For instance, the focal distance compensator (7) includes a convex lens (43) located between an objective lens (41) and a laser diode (42) and designed to be able to be located in or out of an optical path. In accordance with the above-mentioned apparatus, the focal distance compensator adjusts a focal distance of a light emitted from the light source in accordance with the measured thickness of a recording medium. Hence, it is always possible to properly record, reproduce and erase data into or from a recording medium. <IMAGE></p> |
