Low noise transmission holographic optical element
AssigneeHughes Aircraft Company
InventorsGaylord E. Moss, John E. Wreede
Life of this patent
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Abstract
A holographic recording medium is treated to reduce or eliminate unwanted extraneous diffraction in a volume transmission hologram. Surface regions of the medium are desensitized either before or after a holographic recording to reduce the contrast of the holographic fringe pattern along the surfaces, and thereby to eliminate planar phase grating effects. Treatments include applying a burst of gas or vapor to the surface, irradiating the surfaces with highly absorbed incoherent light, thermally treating the recording medium.
Claims26
A method for reducing extraneous diffraction due to surface effects in volume transmission holograms, comprising:
- applying a layer of light sensitive holographic recording medium to a substrate;
- treating said layer to reduce light sensitivity at and adjacent surface regions thereof;
- and
- exposing said recording medium to coherent light so as to strike said light sensitive holographic material symmetrically to record a volume transmission hologram therein with fringes perpendicular to said surface regions.
A volume transmission hologram comprising:
- a substrate;
- a layer of holographic recording medium mounted on said substrate, said layer having a volume transmission hologram recorded therein with fringes perpendicular to surface regions of said layer, said hologram adjacent surface regions of said recording medium being substantially reduced in contrast from said holograms in the interior of said recording medium.
A method for reducing extraneous diffraction due to surface effects in volume transmission holograms, comprising:
- applying a layer of light sensitive holographic recording medium to a substrate;
- treating said layer to reduce light sensitivity adjacent surface regions thereof;
- and
- exposing said recording medium to coherent light so as to strike said light sensitive holographic recording medium symmetrically to record a volume transmission hologram therein, with fringes perpendicular to said surface regions said treating step comprising applying a first layer of light sensitive material along said substrate, applying an inner layer of light sensitive material over said first layer and applying a second layer of light sensitive material over said inner layer, said first and second layers having less light sensitivity than said inner layer.
A volume transmission hologram, comprising:
- a substrate;
- a layer of holographic recording medium mounted on said substrate, said layer having a volume hologram recorded therein with fringes perpendicular to surface regions of said layer, the portion of the said hologram adjacent surface regions of said medium being substantially reduced in contrast from the portions of the hologram in the interior of said holographic recording medium, said surface regions comprising regions adjacent opposed inner and outer surfaces of said holographic recording medium.
A method for reducing extraneous diffraction due to surface effects in volume transmission holograms, comprising:
- applying a layer of light sensitive holographic recording medium to a substrate;
- treating said layer to reduce light sensitivity adjacent opposed surface regions thereof;
- and
- exposing said recording medium to coherent light so as to strike said light sensitive holographic recording medium symmetrically to record a volume transmission hologram therein with fringes perpendicular to said surface regions, wherein said treating step comprises separately exposing said opposed surface regions to highly absorbed incoherent light.
Dependencies are inferred from the claim text.