ABSTRACT
This chapter focuses on the design of binary optics for obtaining super-resolution and long depth of focus (DOF) in an optical data storage system. The extended DOF is critical for near-field recording using a solid immersion lens (SIL), typically with less than 100 nm working distance and extremely fast beam divergence after the SIL exit surface, with the long DOF, the divergence of the beam will be reduced, which makes the beam size less sensitive to the variation of the gap between the optical head and the disk, and therefore, it eases the near-field tracking and serving. Further incorporation of optical antennas into the near-field storage system may produce a light spot of around 10 nm, which allows optical recording with a capacity of 30 TB/disk.
