Reflection polarizing holographic optical element for compact magnetooptical disk heads

A reflection polarizing holographic optical element with sinusoidal surface-relief has been developed for compact magnetooptical (MO) disk heads. The element has the polarizing beam splitter function as well as the focusing and tracking error signal detection functions. To produce the sinusoidal surface-relief structure with photolithography, a new fabrication process, which includes procedures for converting a rectangular profile into a sinusoidal profile, is introduced. Replicas were also fabricated with high replication fidelity using the photopolymerization method. The developed element was used in an MO disk head. A 57-dB C/N ratio, which is sufficient value for practical use was achieved for a 1-MHz readout signal.