| 摘要 |
PURPOSE:To simplify the optical system and to facilitate the assemblage and adjustment by changing the light path of one part of a light source beam and performing a focusing control with reflected light from an optical recording medium due to this change. CONSTITUTION:An optical card 1 is irradiated with the light of the light source from an LED 2 via a collimator lens 3, a beam splitter 4 and an objective lens 5. The reflected light of this is incident upon a photo detector 8 via the lens 5, the beam splitter 4 and a condenser lens 7, so that the recording contents of the card 1 are optically read out to be reproduced. This beam splitter 4 is provided with a light reflecting part 4a so that one part of the light source beam is changed in its light path to project on the card 1 in a slantwise direction, and the reflected light is incident upon a different position of the detector 8, and hence the focusing control is performed in accordance with the result of receiving the light. As a result, the optical system is simplified, and the assemblage and adjustment can easily be carried out. |
