| 摘要 |
PURPOSE:To reduce the cost of a multihead pickup device by providing a semiconductor laser chip which emits the laser beams through its front and rear faces and a means which condenses the beams emitted from the semiconductor laser chip to each optical disk. CONSTITUTION:The laser beam P1 emitted through the front face of a semiconductor laser chip 8 passes through a hologram element 9 fixed to a semiconductor laser package and condensed on an optical disk 12 through a collimator lens 10 end an objective lens 11. Meanwhile the laser beam P2 emitted through the rear face of the chip 8 is condenced on an optical disk 17 through a hologram element 14, a collimator lens 15, and an objective lens 16. The laser beam P4 reflected on the disk is deflected by the element 14 through an adverse route end made incident on a signal reading photodiode 18. Then the disk signals are read. In such a constitution, the structure end the production process of a multihead pickup device can be simplified. |
