Abstract
Researches on the residual birefringence of injection molded substrates for optical disc are reviewed. Molding factors on the occurrence of the birefringence and the influence of the molding conditions on the three dimensional birefringences of polycarbonate substrates are discussed. Relationships between the birefringence (n1-n2) in the plane and (n1-n3) in the cross section and melt temperature, mold temperature, injection rate and cooling time, etc. are clarified quantitatively.
