| 摘要 |
PURPOSE:To prevent a tracking pit from being omitted, by using an argon laser for a signal and a helium cadmium laser for a tracking groove, respectively. CONSTITUTION:A light source 1 is an argon laser, and a light source 2 is a helium cadmium laser. The argon laser is used for recording an information signal, and the helium cadmium laser which has a lot of noises and a small laser output, but causes no temporary drop nor stop of the laser output in the course of its use is used for recording a tracking signal, by which it is prevented that a tracking control signal becomes in a non-recording state. |
