US Patent 7949216 Bragg grating elements for optical devices

Three-dimensional holographic elements are disclosed. Three-dimensional Bragg gratings recorded on bulks of optical material are included in the disclosure. Such elements may be manufactured by placing a three-dimensional bulk of optical material directly behind a recorded master hologram, directing a reference beam onto a master hologram such that a replica of the master hologram is recorded in the optical material. The replica may form the three-dimensional holographic element. The master hologram may be Bragg grating formed on a surface of a transparent substrate.