| 摘要 |
PROBLEM TO BE SOLVED: To perform sure focus control to a guide surface and to stable focus control to plural recording layers with respect to a three-dimensional optical recording medium with a simple constitution. SOLUTION: In this device 1, the guide beam from a semiconductor laser 3 for guide is made into approximately parallel light beams by a focus regulating lens 6 held at a lens holder 5 via a hologram 4. The guide beams made into the approximate parallel light beams are cast to the guide surface 9b by an objective lens 8 via a wavelength separation mirror 7. The focus withdrawal of the guide beams to the guide surface 9b is executed by detecting the position of the regulating lens 6 by a position detector 10 and controlling a focus regulating actuator 12 which executes the focus regulation by a servo circuit 11 which moves the lens holder 5 in an optical axis direction and an objective lens actuator 13 which moves the objective lens 8 in the optical. |
