Optical disk

Abstract

Abstract PURPOSE:To obtain an optical disk having an extremely small double refractive index and excellent optical homogeneity by copolymerizing a monomer which yields a resin having a positive photoelastic modulus and a monomer which yields a resin having a negative modulus to obtain a resin having approximately zero photoelastic modulus and using such resin to form the disk. CONSTITUTION:The resin formed by copolymerizing >=1 kinds of the monomer selected from the group including styrene, vinyl toluene, cyclohexyl methacrylate and phenyl methacrylate which yields a resin having a positive photoelastic modulus and at least one of methyl methacrylate and alpha-methyl styrene which yields a resin having a negative photoelastic modulus is obtd. in such a way that the photoelastic modulus thereof attains >=-1X10<-13>cm<2>/dyne and <=+1X10<-13>cm<2>/ dyne by changing the compsn. ratio of both kinds of the monomers. The optical disk which has an extremely small double refractive index, has good optical uniformity, performs reading out of the signal recorded by reflection or transmission of laser light and has excellent image and acoustic quality is obtd. by using such resin as a disk base material.

Inventors

• 👤 Hiroaki Usui
• 👤 宏明 碓氷
• 👤 Shinobu Ikeno
• 👤 池野　忍
• 👤 Masashi Nakamura
• 👤 正志 中村
• 👤 Tetsuya Takanaga
• 👤 高永　哲也

Bibliographic Details