Hughes Electronics Corporation

Hughes Aircraft Company

Stephen T Babbitt

John E Wreede

James E Scott

Richard B Upper

Darrell F Hatch

Lane W Cosner

Method and apparatus for monitoring wavelength shift in a holographic light protection filter to determine if the hologram has been damaged by moisture. The hologram is provided with first, second and third areas. The first area is an extra moisture protected area covered by a moisture resistant material. The second area is adjacent to the first area and is recorded at a different wavelength than the bulk of the hologram. The third area is the remainder of the hologram. The user compares light reflections at these specific areas of the hologram and observes color variations to determine if the hologram has been damaged by moisture. In another embodiment, scribe lines are drawn in the hologram through the three areas. The user detects moisture damage by observing the apparent displacement of these scribe lines in the three areas when viewed through a diffraction grating.

Apparatus and method for monitoring holographic light protection filters

A hologram exposure system that includes a holographic recording medium, a holographic prism adjacent the holographic recording medium for most efficiently diffracting light of a predetermined wavelength and at a predetermined incidence angle, a first monochromatic beam directed toward the holographic prism at the predetermined incidence angle, and a second monochromatic beam directed toward the holographic prism at an incidence angle that allows the second monochromatic beam to be transmitted by the holographic prism without any diffraction. The holographic prism diffracts the first monochromatic beam and transmits the second monochromatic beam without any diffraction to produce a diffracted first construction beam and a non-diffracted second construction beam which interfere in the holographic recording medium to form holographic fringes therein. The exposure system further includes a holographic zero order filter interposed between the holographic prism and the holographic recording material for diffracting away from the holographic recording medium a portion of the first monochromatic beam that is not diffracted by the holographic prism.

Holographic exposure prism

An encoded hologram strip including a plurality of hologram digits linearly arranged along a longitudinal direction, each hologram digit including at least 0 parallel fringe reflection holograms wherein each parallel fringe hologram is constructed to diffract playback light having a predetermined wavelength and incidence angle at a diffraction angle that is substantially equal to the playback incidence angle.

Growing community of inventors

Redondo Beach, CA, United States of America

Stephen T Babbitt