| 摘要 |
PURPOSE:To simplify the constitution of an optical device by sharing the constitution for both a beam splitter and a focus controller when at least one of record and reproduction is carried out together with the erasion of the record contents. CONSTITUTION:The record/reproduction light beam is projected to a polarized beam splitter from a light source 24 and reflected by the splitter 28 to be focused by a record/reproduction lens 30 via a wavelength plate 29. This focused beam is irradiated to an optical disk 21 and this reflected light is received by a photodetector 32. While an erasion light beam sent from a light source 35 is reflected by the splitter 28 and irradiated to the disk 21 via a focusing lens 37. The output of the detector 32 is applied to a focus control circuit 44 to give the focus control to lenses 30 and 37 as well as displacement means 38 and 41. In such a way, the splitter 28 and the circuit 44 are shared to simplify the constitution of an optical disk device. |
