| 摘要 |
<p>Apparatus for reading information out of an optical recording medium, such as an optical card, includes a semiconductor laser diode (2) for emitting a laser beam, a collimator lens (3), a beam splitter (5), an objective lens (6), converging lens (7) and a photodetector (8). The laser beam emitted from the laser diode (2) is made incident upon an optical card (1) to be read via the collimator lens (3), beam splitter (5) and objective lens (6), and a light flux reflected by the optical card (1) is made incident upon the photodetector (8) via the objective lens (6), beam splitter (5) and converging lens (7). The laser diode (2) and collimator lens (3) are arranged such that the laser beam is projected upon the optical card (1) in a de-focused condition, while the objective lens (6) is focused on the optical card (1). Such apparatus can enable information to be read out accurately from an optical recording medium, whilst at the same time permitting the construction of the apparatus to be simple and compact in comparison with some prior art apparatus.</p> |
