Holographic optical head.

摘要

A holographic optical head comprises a substrate (62) having a laser diode (64) and a photodetector (66). A coherent beam from the laser is diffracted by hologram (70) and passes through a hologram beam splitter (76) and a quarter-wave plate (78) to a focusing hologram (82) which diffracts and focuses the beam on a record medium (84). Light reflected from the medium is again diffracted by the hologram (82) and is separated from the incoming beam by the beam splitter (76), and is diffracted by hologram (72) on to the detector (66).