| 摘要 |
PURPOSE:To achieve high-density recording by forming a readable guide track on an information recording medium and by positioning a light beam on the basis of the position of the guide track. CONSTITUTION:In the information recording areas of an information recording medium 12, an information track 14 are formed and at boundaries between the information recording areas, a guide track 13 is formed. A recording and reproducing device is provided with a laser 16 for recording and reproduction and a tracking laser 17 for reading the guide track, and both of them differ in wavelength of laser light. Light beams from both of them are guided to a common optical system 20 through collimating lens 18 and 19 and then focused on the information recording medium 12 through a common objective lens 21. When the radial position of the objective lens 21 is so set that a light spot from the tracking laser 17 follows up the guide track 13, the relative distance between light spots 27 and 28 is determined unequivocally by the inclination of a movable mirror 22. |
