Hd dual-layered optical disc

Abstract

A high-density dual-layer optical disc of the present invention is configured so that the first substrate thickness from the light incidence surface of a transparent substrate to the first recording layer is equal to a value obtained by subtracting half the distance between the first and the second recording layers from the substrate thickness from the light incidence surface of a transparent substrate to a recording layer in a general high-density single layer optical disc, and the second substrate thickness from the light incidence surface to the second recording layer is equal to a value obtained by adding half the distance between the two recording layers to the substrate thickness from the light incidence surface to the recording layer in the general high-density single layer optical disc.

Description

[0001] This application is a divisional application of the patent application with the application number PCT / KR03 / 01095 and the invention name "High Density Dual-Layer Optical Disk", which entered the Chinese national phase on February 27, 2004, and was submitted on June 4, 2003. technical field [0002] The present invention relates to a high density dual layer optical disc with first and second recording layers both positioned on one side of a central plane bisecting the thickness of the disc and close to the disc surface. Background technique [0003] FIG. 1 shows the structure of a general DVD (Digital Versatile Disc). As shown in FIG. 1 , a DVD represented by reference numeral 10 has a diameter of 120 mm and a thickness of 1.2 mm, and has a central hole with a diameter of 15 mm and a clamping region (clamping region) with a diameter of 44 mm, which is suitable for use by The turntable and clamp included in the disc unit clamp. [0004] The DVD 10 has a recording layer...

AI Technical Summary

Problems solved by technology

[0010] However, in the case of a high-density dual-layer optical disc as described above, there is no way to effectively limit the wavefront error that must be generated over the entire optical disc by the light incident from the light-transmitting substrate. Spherical aberration produced by variations in substrate thickness from the surface to the respective first and second recording layers and coma aberration produced by the tilt of the objective lens contained in the optical pickup device

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