Side lobe suppression in holograms using pre-exposure
AssigneeHughes Aircraft Company
InventorsJohn E. Wreede, James A. Arns
Life of this patent
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Abstract
A holographic recording medium is treated to eliminate side lobes. The method involves exposing opposed surfaces of the medium with filtered incoherent light either before or after a holographic exposure with coherent light. The incoherent exposure produces controlled desensitization of the medium, resulting in a sensitivity profile which increases continuously to a maximum near the center of the layer. A hologram recorded in the layer has a refractive index modulation which is high in the center of the layer and which decreases toward the surfaces of the layer.
Claims13
Method of making a hologram having an efficiency curve with substantially reduced side lobes comprising:
- preparing a thin layer of holographic recording medium having opposed surfaces;
- exposing said surfaces of the layer to filtered incoherent light in a manner to produce a sensitivity profile therein which is substantially zero at said surfaces and increases substantially continuously to a maximum in the vicinity of the center of the layer;
- and
- exposing said layer having said sensitivity profile to coherent light beams to record a hologram fringe pattern therein.
A hologram comprising a thin layer of holographic recording medium having opposed surfaces, said medium having a light sensitivity profile which increases substantially continuously to a maximum in the vicinity of the center of the layer.
Method for making a holographic recording structure comprising:
- preparing a thin layer of holographic recording medium having opposed surfaces;
- and
- exposing said surfaces to filtered incoherent light in a manner to produce a sensitivity profile therein which increases substantially continuously to a maximum in the vicinity of the center of the layer.
Dependencies are inferred from the claim text.