Optical characteristics of injection-molded fluorene polymers

Abstract

Abstract Digital cameras are small, but they must be able to take images with numerous pixels. To use few lenses in devices, aspheric lenses have been used. Fluorene-based polymers (FBPs) have a high refractive index and low birefringence. Because optical lenses must be manufactured as designed with low optical retardation, FBP optical lenses are widely used. This study assessed optical and flow characteristics of polycarbonate (PC) and two kinds of FBP. Molded specimen characteristics of PC and two FBPs revealed these properties of the FBPs. The results show that the unique structure of FBPs eliminated birefringence, because of the cardo structure part, including the fluorene ring. Differences in optical properties are attributable to structural differences of the part which is polymerized with the fluorene structure (the X part). The temperature dependence of FBPs in the flow characteristics and optical properties was smaller than that of PC; the slight temperature dependence is particularly obvious above the glass transition temperature (Tg). The benzene ring content of FBP affects the resin optical and physical properties. The influence of the difference between the fluorene polyester structure and the PC structure was greater than that of the benzene ring content in the X part, in the molecular structure of FBP.