| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical member for an information reading/writing device, the member having preferable durability against short wavelength laser beams such as a blue laser. SOLUTION: The optical member for an information reading/writing device is produced by molding a copolymer material containing a methyl methacrylate unit and a unit derived from a lactone compound expressed by the general formula (1). The member is suitable for an objective lens, prism, condenser lens, grating, collimator lens and sensor lens. In formula (1), each of R<SP>1</SP>and R<SP>2</SP>independently represents a hydrogen atom, a methyl group or an ethyl group, wherein the total carbon number in R<SP>1</SP>and R<SP>2</SP>is 1 to 3. COPYRIGHT: (C)2006,JPO&NCIPI
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