Title:
OPTICAL DISC SUBSTRATE
Document Type and Number:
Japanese Patent JP2002234953
Kind Code:
A
Abstract:
To provide a substrate for optical discs which enables an increase of the numerical aperture and a shortening of wavelengths in optical heads.
The substrate comprises a hydrogenated styrene copolymer having a weight average molecular weight of ≥60,000 g/mol which contains from 85 to 95 wt.% hydrogenated styrene polymer unit. The retardation (absolute value) at an incidence angle of 0 or 30° from the normal direction of the substrate surface at a wavelength of 633 nm is ≤10 nm in a single pass, and the thickness of the substrate is ≤0.7 mm.
Inventors:
KIDO NOBUAKI
MATSUMURA SHUNICHI
SUZUKI KAZUTOMI
MATSUMURA SHUNICHI
SUZUKI KAZUTOMI
Application Number:
JP2001033459A
Publication Date:
August 23, 2002
Filing Date:
February 09, 2001
Export Citation:
Assignee:
TEIJIN LTD
International Classes:
C08J5/18; C08L25/10; G11B7/24047; G11B7/2533; G11B7/2536; (IPC1-7): C08J5/18; C08L25/10; G11B7/24
Attorney, Agent or Firm:
Maeda Junhiro