Holographic optical elements having a reflection hologram formed in a photopolymer
AssigneeE. I. Du Pont de Nemours and Company
InventorsDalen E. Keys, William K. Smothers, Albert F. Harrington, Jacob Beutel, Scott R. Schicker, Dillion F. Scofield
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Abstract
Improved holographic optical elements are disclosed that contain a reflection hologram. Also, an improved process for forming reflection hologram.
Claims69
A holographic optical element comprising a transparent polymeric film containing a reflection hologram, said film having a refractive index modulation greater than approximately 0.001 and being formed by exposing to coherent light a composition consisting essentially of:
- (a) approximately 25 to 90% of a polymeric binder selected from the group consisting of polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl formal, interpolymers containing major segments thereof, and mixtures thereof;
- (b) approximately 5 to 60% of an ethylenically unsaturated liquid monomer containing at least one phenyl, biphenyl, phenoxy, naphthyl, naphthyloxy, heteroaromatic group containing up to three aromatic rings, chlorine or bromine moiety;
- (c) approximately 0 to 25% of a plasticizer;
- and
- (d) approximately 0.1 to 10% of a photoinitiator system activatable by actinic radiation
- wherein said percentages are weight percentages based on total film weight.
In a process for forming a reflection hologram wherein a reference beam of coherent actinic radiation and an object beam of the same coherent actinic radiation enter a layer of recording medium from opposite sides to create an interference pattern in the medium that forms the hologram, the improvement wherein the medium is a photopolymerizable film layer consisting essentially of:
- (a) a polymeric binder selected from the group consisting of polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl formal, interpolymers containing major segments thereof, and mixtures thereof;
- (b) an ethylenically unsaturated liquid monomer containing at least one phenyl, biphenyl, phenoxy, naphthyl, naphthyloxy, heteroaromatic group containing up to three aromatic rings, chlorine or bromine moiety;
- and
- (c) a photoinitiator system activatable by the actinic radiation
- and the resulting imaged medium has a refractive index modulation of at least approximately 0.001.
A process for forming a reflection hologram in a photopolymerizable film recording medium comprising:
- A. Projecting a reference beam of coherent actinic radiation on a first side of the recording medium which consists essentially of:
- (1) a polymeric binder selected from the group consisting of polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl formal, interpolymers containing major segments thereof and mixtures thereof;
- (2) an ethylenically unsaturated liquid monomer containing at least one phenyl, biphenyl, phenoxy, naphthyl, naphthyloxy, heteroaromatic group containing up to three aromatic rings, chlorine or bromine moiety;
- and
- (3) a photoinitiator system activatable by the actinic radiation;
- B. Concurrently projecting an object beam of the same coherent actinic radiation approximately in an opposite direction to the reference beam onto a second side of the photopolymerizable film so as to intersect with the reference beam in a plane within the film whereby a reflection hologram is formed;
- C. Irradiating the imaged photopolymerizable layer with uniform source of actinic radiation;
- said resulting imaged medium having a refractive index modulation of at least approximately 0.001.
Dependencies are inferred from the claim text.