Hitachi and InPhase Assigned Patent Number 7,990,830

Hitachi and InPhase Technologies have been assigned a patent (7,990,830) developed by four co-inventors for an “optical pickup, optical information recording apparatus and optical information recording and reproducing apparatus using the optical pickup.”

The co-inventors are Kenichi Shimada, Yokohama, Japan, Tatsuro Ide, Kawasaki, Japan, Kevin R. Curtis, Longmont, Colo., and Ken E. Anderson, Longmont, Colo.

The abstract of the patent published by the U.S. Patent and Trademark Office states: “In holographic recording, it is important to form stably an interference fringe between a reference beam and a signal beam in a holographic storage medium. To suppress factors degrading stability of the interference fringe, such as fluctuation of atmospheric air, position displacement of optical components and the like during propagation of the reference and signal beams, an optical pickup and an optical information recording/reproducing apparatus adopt an optical system structure providing a higher proportion of optical components shared by the reference and signal beams optical path than conventional optical system structure. To increase the proportion of shared optical components, the signal beam and the reference beam pass through the PBS prism as parallel beams and a concave lens is placed on a reference beam path just before the objective lens.”

The patent application was filed on Feb. 27, 2008 (12/038,150).