| 摘要 |
PURPOSE:To attain the optimum combination of the width and the depth for both the group part for reproduction signals and the bit part for track numbers, by leading the luminous flux made incident on a photosensitive material to an objective lens after changing its diameter and controlling the luminous flus led to the changing means by a control means. CONSTITUTION:A beam 24 sent from an argon laser 23 of a master disk producing device is separated into luminous fluxes 26 and 27 by a half mirror 25 and then made incident on the sets 30 and 31 as well as 32 and 33 of convex lenses of beam expanders 45 and 46 via optical modulators 28 and 29 serving as the control means. The diameters of both luminous fluxes 26 and 27 are changed by the expanders 45 and 46. Then the luminous flux given from the expander 45 is turned by 90 deg. through a 1/2 deflecting plate 34 and supplied to an objective lens 36 together with the luminous flux given from the other expander 46. The lens 36 is moved by a focus serve system together with a master disk 21 coated with resist. Thus the optimum combination of the width and the depth is secured for both the group part for reproduction signals and the bit part for track numbers respectively. |
