一、发生双折射的介质。 目前用于光盘存储的基片材料是聚碳酸酯(polycarbonate)、聚甲基丙烯酸甲酯、改性双酚A环氧树脂和非晶态聚烯烃等高聚物光盘基片,其中聚碳酸酯是最重要的光盘基片材料。作为聚合物光盘基片材料,要求具有高的透光率、光学纯度、尺寸稳定性和热 First, the occurrence of birefringence medium. Substrate materials currently used for optical disk storage are high polymer optical disk substrates such as polycarbonate, polymethylmethacrylate, modified bisphenol A epoxy resins, and amorphous polyolefins, in which polycarbonate Is the most important optical disc substrate material. As a polymer optical disc substrate material, it is required to have high light transmittance, optical purity, dimensional stability and heat