DEPENDENCE OF THE TRACKING PERFORMANCE OF AN OPTICAL DISK ON THE DIRECTION OF THE INCIDENT-LIGHT POLARIZATION

In optical-disk data-storage systems, the signal that provides trackin g information is dependent on the groove shape, the optical constants of the materials involved, and the polarization state of the incident light. In this paper, we show that the tracking signal can be describe d by two measurable quantities, both of which are largely independent of aberrations in the optical system. Using these two quantities, we m atch the tracking performance of a given disk to an equivalent disk ha ving rectangular grooves-the adjustable parameters being the rectangul ar groove depth and the duty cycle. By assumption, these rectangular g rooves modulate only the phase of the incident beam and disregard its state of polarization. The effective groove depth and the duty cycle t hus become dependent on the polarization state of the incident beam. W e examine these dependences for various disks having different groove geometries and different combinations of materials. (C) 1995 Optical S ociety of America