| 摘要 |
PURPOSE:To accurately perform recording, reproduction, and erasure by fixing collimator lenses on lens barrels provided integrally with a substrate so as to enclose the peripheries of two semiconductor lasers, respectively. CONSTITUTION:The lens barrels 31 and 32 of the collimator lenses 11 and 21 are mounted directly on the substrate 30 which fixes the n semiconductor lasers 1 and 2. In other words, the collimator lenses 11 and 21 which collimate the laser beams are structure in such a way that they are not operated independently for the semiconductor lasers 1 and 2. Therefore, when expansion or compression due to the temperature is generated in the same substrate 30 on which the semiconductor lasers 1 and 2 are mounted, the quantities of travel of the two semiconductor lasers 1 and 2 become almost equal to that of the lens barrels 31 and 32 on which the collimator lenses 11 and 21 to collimate the semiconductor lasers 1 and 2 are mounted. In such a way, it is possible to always keep parallelism between two emitting laser beams, and to perform the recording, the reproduction, and the erasure accurately. |
