ABSTRACT
This chapter discusses theory, simulations, and practical implementation for beam-shaping techniques used in optical data storage. It describes the optical system transfer function and how it relates to optical data storage devices. The chapter examines beam-shaping filters, including illumination-path filters, return-path filters, electronic filters, and filter combinations. Beam shaping techniques for data storage applications fall into two general categories: those that implement filters in the illuminating path and those that implement filters in the return path. The system used to collect experimental data was designed to work with magneto-optic media. The laser beam is modulated between high power and low power as the disk spins in order to write a pattern of data marks along each track. Phase filtering, as with amplitude filtering, improves the optical data storage system in its ability to write and read smaller marks. The reduction of overlap area explains the falloff in the transfer function as the spatial frequency of the data pattern is increased.
