Lowly birefringent polymer, process for the production thereof, and optical pickup lens

摘要

A copolymer having low birefringence substantially consisting of a repeating unit represented by the following general formula (1) and a repeating unit of a (meth)acrylate:wherein, R1 represents a hydrogen atom or a hydrocarbon group having 1 to 25 carbon atoms, an alicyclic hydrocarbon group or a substituted hydrocarbon group.). This copolymer has low birefringence and low hydrophilia, is excellent in transparency, heat-resistance and mechanical strength, and can be applied to lenses, optical disks, optical fibers and the like.