| 摘要 |
PURPOSE:To stabilize S/N of an optical pickup device, by forming a single longitudinal mode and multiple longitudinal mode semiconductor lasers unitedly and using the former for recording and latter for reproducing, and then, making the output of the former coincident with the optical axis of an object lens and inclining that of the latter against the optical axis. CONSTITUTION:Two semiconductor lasers, one of which is single longitudinal mode type one and the other of which is multiple longitudinal mode type one, are united and the former is used for recording and latter for reproducing. The light 14 outputted from the single longitudinal mode semiconductor laser is made incident to an object lens, with the incident angle being almost coincident with the optical axis 12 of the lens. The light 13 outputted from the other laser is made incident to the object lens, with its incident angle being inclined against the optical axis 12 by a prescribed angle. Therefore, the quantity of the return light of the light 13 tends to change, but the light is hardly affected by the returning light because the laser is multiple longitudinal mode type one. The light 14 is apt to be affected by the return light, but fluctuation of the return light quantity caused by the position of this pickup, etc., hardly occurs. Therefore, information can be recorded and reproduced with stable S/N. |
