Influence of injection molding process on the local fluctuations of magneto-optical signals

The local fluctuations of magneto-optical (MO) signals were investigated in the vicinity of the preformat pits of polycarbonate (PC) substrates fabric ated under different injection molding conditions and also using stampers w hich had different shapes of. grooves and preformat pits. A strong correlat ion was observed between the substrate birefringence and the fluctuation of , the MO signal. The rate-of-change of the fluctuations, as the phase shift of the optical head was varied, was attributed to the shapes of preformat pits and grooves. The fluctuation of the MO signal could be controlled by v arying the injection molding conditions and the shapes of preformat pits an d grooves.