HOLOGRAPHY OPTICAL HEAD

摘要

A holographic optical head for imaging a laser diode for optical storage or magnetic tracking applications includes three holograms, a beam director and a quarter-wave plate. In a preferred embodiment the beam director is a fourth hologram. The holographic optical head is corrected for aberrations arising from its use with light sources other than the design wavelength by having the first hologram diffract the light into the -1 order direction. This light is then diffracted by the second hologram into the +1 order so as to eliminate aberrations normally caused by wavelength shifts of the laser source.