| 摘要 |
PURPOSE:To reduce the weight and the size by converging the light from two light sources onto an optical disk by one objective lens so as to record, reproduce and erase through the use of one light and to extract error signals by the other light. CONSTITUTION:Lights from two light sources LD1 and LD2 are converged onto an optical disk 1 by one objective lens 1. And information recording, reproducing and erasing with respect to the disk 1 are done by the light from LD1. On the other hand, the light from LD2 is reflected by the disk 1, diffracted by a hologram 9 to become two light beams one of which is received by PD1 to be extracted as focus error signals and the other is received by PD2 as track error signals. Having this constitution, dedicated light source power for operations such as an information recording becomes small, semiconductor lasers and photodiodes are formed in monolithic so as to make a position precision high and the number of adjustments is reduced. Furthermore, the light sources and a signal processing system are enclosed in one package to provide a compact and light weight optical head. |
