| 摘要 |
PURPOSE:To decrease the double refraction viewed from the entire part and to improve the performance of a recording medium by providing a transparent plastic layer having the double refraction of the polarity reverse from the polarity of a transparent plastic substrate having double refraction to the surface of said substrate on the side opposite from the recording layer thereof. CONSTITUTION:The recording layer 2 is formed on the rugged surface of the transparent plastic substrate 1 having double refraction and the surface thereof is coated with a protective layer 3. The transparent plastic layer 5 which exhibits the double refraction of the polarity reverse from the polarity of the double refraction of the substrate 1 is laminated by adhesive agent on the surface of the substrate 1 on the side opposite from the recording layer. Laser light for information reproduction is projected to the medium from the layer 5 side and arrives at the layer 2 by transmitting the layer 5 and the substrate 1. The reflected light transmits the substrate 1 and the layer 5 and enters an optical pickup. The double refractions of the layer 5 and the substrate 1 are, therefore, offset by each other in the route of said light by which the double refraction viewed from the entire part are decreased. The performance of the recording medium is thereby improved. |
