Mesh size control of holographic photopolymer and method for making the same

Abstract

The present disclosure relates to a novel holographic photopolymer and method for making the same. In some embodiments, the holographic photopolymer may comprise a polyurethane matrix, a writing monomer, and a dye system. In some embodiments, the polyurethane matrix may comprise a mesh size and a storage modulus. In some embodiments, the polyurethane matrix may comprise a liquid additive. In some embodiments, the storage modulus of the polyurethane matrix increases from about 10² Pa to about 5x10⁵ Pa as the mesh size decreases. In some embodiments, an augmented reality / virtual reality (AR / VR) apparatus comprising the holographic photopolymer is described.

Description

PCT Application 134075-0005WO01 MESH SIZE CONTROL OF HOLOGRAPHIC PHOTOPOLYMER AND METHOD FOR MAKING THE SAME Inventors: Nan Hu, Masanori Hosoyamada, Hongxi Zhang, Sergey Simavoryan, and Massarrah Alkinani FIELD

[0001] The present disclosure is related to a holographic photopolymer for use in AR / VR glasses, optical displays, and other holographic applications. BACKGROUND

[0002] As the use of augmented reality glasses and optical displays become more common, the demand for improved holographic media have increased. Holographic media or materials can be produced from holographic gratings, e.g., a volume holographic grating. For example, (as taught in U.S. Patent No.9,281,000 B2 and 8,771,904 B2) a photopolymer formulation is disclosed comprising chemically crosslinked matrix polymers, writing monomers, and a photoinitiator system for producing holographic media via volume holographic gratings. However, the process to produce this photopolymer formulation requires an expensive nitrogen purge to remove oxygen. This can result in deficient polymerization of the polymers due to radicals being oxidized if the oxygen is not completely removed.

[0003] Furthermore, the ability to control the refractive index is essential to achieve high reflections efficiency and high refractive index modulation. A high refractive index is essential to achieve highly visible holograms. Most volume grating hologram films for AR / VR glasses can only achieve 50% reflection efficiency but have a thickness, greater than 12 µm resulting in a low refractive index modulation.

[0004] As such, improved holographic media and methods for producing holographic media are needed. More particularly, holographic photopolymers / films with a high refractive index modulation greater than 0.03, transmittance greater than 90%, and low haze of less than 1.5%.PCT Application 134075-0005WO01 SUMMARY

[0005] The present disclosure solves these problems and generally relates to a novel holographic photopolymer and method for making the same. In some embodiments, a holographic photopolymer is described. In some embodiments, the holographic photopolymer may comprise a polyurethane matrix. In some embodiments, a polyurethane matrix is described. In some embodiments, the polyurethane matrix may comprise a mesh size and a storage modulus. In some embodiments, the storage modulus of the polyurethane matrix increases from about 10² Pa to about 5x10⁵ Pa as the mesh size decreases.

[0006] In some embodiments, the polyurethane matrix may comprise a first polypropylene glycol diol, aliphatic polyisocyanate; and wherein the mesh size is about 1 nm to about 5 nm. In some embodiments, the polyurethane matrix may comprise a first polypropylene glycol diol, polypropylene glycol triol, dicyclohexylmethane diisocyanate; and wherein the mesh size is about 5 nm to about 10 nm. In some embodiments, the polyurethane matrix may comprise a first polypropylene glycol diol, a second polypropylene glycol diol, polypropylene glycol triol, dicyclohexylmethane diisocyanate; and wherein the mesh size is about 10 nm to about 40 nm.

[0007] In some embodiments, the polyurethane matrix may further comprise a liquid additive. In some embodiments, the liquid additive may comprise ethylene glycol, propylene glycol units, ester units, or a combination thereof.

[0008] In some embodiments, the holographic photopolymer may comprise a polycyclic writing monomer and a dye system. In some embodiments, the polycyclic writing monomer may comprise a difunctional writing monomer or a monofunctional writing monomer. In some embodiments, the polycyclic writing monomer may comprise ethoxylated bisphenol a diacrylate, ethoxylated fluorene diacrylate, m-phenoxybenzyl acrylate, biphenylmethyl acrylate, or a combination thereof. In some embodiments, the dye system may comprise a dye and a co-initiator. In some embodiments, the dye system may comprise a dye and a co-initiator. In some embodiments, the ratio of dye and the co- initiator is about 1:10 to about 1:14.PCT Application 134075-0005WO01

[0009] In some embodiments, the holographic photopolymer may comprise a solvent. In some embodiments, the solvent may comprise 1-ethyl-2-pyrrolidone.

[0010] In some embodiments, the holographic photopolymer may comprise a tin catalyst solution. In some embodiments, the tin catalyst solution may comprise a 10% dimethyltin dineodecanoate and 90% 1-ethyl-2-pyrrolidone.

[0011] In some embodiments, the weight percent of the polyurethane matrix to the polycyclic writing monomer is 10-90%.

[0012] In some embodiments, an augmented reality / virtual reality (AR / VR) apparatus is described. In some embodiments, the AR / VR apparatus may comprise the holographic photopolymer described above. In some embodiments, a film is described. In some embodiments, a film may comprise the holographic photopolymer described above.

[0013] These and other embodiments are described in greater detail below. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG.1 is a graph showing the storage modulus of an embodiment described herein.

[0015] FIG.2 depicts a film processing procedure as described herein.

[0016] FIG.3 is a graph showing the measured data of the transmittance spectrum of an embodiment described herein.

[0017] FIG.4 is a graph showing the measured data of the resulting Bragg curve of an embodiment described herein.

[0018] FIG.5 is a graph showing the measured data of the resulting Bragg curve of an embodiment described herein.

[0019] FIG.6 is a graph showing the measured data of the resulting Bragg curve of an embodiment described herein.

[0020] FIG.7 is a graph showing the measured data of film transmittance of an embodiment described herein.

[0021] FIG.8 is a graph showing the rheological measurement of an embodiment described herein.PCT Application 134075-0005WO01

[0022] FIG.9 is a graph showing the measured data of the haze and total transmission of an embodiment described herein.

[0023] FIG.10 is a graph showing the measured data of the resulting Bragg curve of an embodiment described herein.

[0024] FIG.11 is a graph showing the measured data of the resulting Bragg curve of an embodiment described herein.

[0025] FIG.12 is a graph showing the measured data of the resulting Bragg curve of an embodiment described herein.

[0026] FIG.13 is a graph showing the storage modulus of an embodiment described herein.

[0027] FIG.14 is a graph showing the measured data of the resulting Bragg curve of an embodiment described herein. DETAILED DESCRIPTION

[0028] In some embodiments, the current disclosure describes a holographic media for use in augmented reality / virtual reality (AR / VR) apparatus and / or optical displays. In some embodiments, a holographic photopolymer is described. In some embodiments, the holographic photopolymer may comprise a polyurethane matrix. In some embodiments, the holographic photopolymer may comprise a polyurethane matrix, a writing monomer, and a dye system. In some embodiments, the holographic photopolymer may comprise a polyurethane matrix, a writing monomer, a dye system, and a solvent.

[0029] In some embodiments, the polyurethane matrix may comprise a mesh size and a storage modulus. In some embodiments, the mesh size and storage modulus of the polyurethane matrix may be tuned to improve the diffusion of the writing monomer by changing the refractive index modulation. In some embodiments, the storage modulus of the polyurethane matrix may increase from about 10² Pa to about 5x10⁵ Pa as the mesh size decreases.

[0030] In some embodiments, the components of the polyurethane matrix are selected based on the mesh size and storage modulus of the polyurethane matrix. ByPCT Application 134075-0005WO01 controlling the mesh size and storage modulus of the polyurethane matrix had the unexpected result of being able to tune the refractive index known to be associated with the mesh size and storage modulus, thus improving the viewing experience of the user utilizing a AR / VR headset comprising the holographic photopolymer. In some embodiments, the composition of the polyurethane matrix is obtained by the selection of a first polypropylene glycol diol, a second polypropylene glycol diol, an aliphatic polyisocyanate, a polypropylene glycol triol, a dicyclohexylmethane diisocyanate, or a combination thereof. FIG.1 is a graph depicting the change in the storage modulus of the holographic photopolymer for three different compositions of the polyurethane matrix without the liquid additive. FIG.13 is a graph depicting the change in the storage modulus of the holographic photopolymer for three different compositions of the polyurethane matrix with the liquid additive.

[0031] In some embodiments, the polyurethane matrix can have a refractive index of about 1.4 to about 1.5, about 1.40, about 1.41, about 1.42, about 1.43, about 1.44, about 1.45, about 1.46, about 1.47, about 1.48, about 1.49, about 1.5, or any refractive index bounded by this range, e.g., 1.468. In some embodiments, the writing monomer can have a refractive index of about 1.5 to about 1.6, about 1.5, about 1.51, about 1.52, about 1.53, about 1.54, about 1.55, about 1.56, about 1.57, about 1.58, about 1.59, about 1.6, or any refractive index bounded by this range, e.g., 1.523.

[0032] In some embodiments, the polyurethane matrix may comprise a first polypropylene glycol diol, aliphatic polyisocyanate; and wherein the mesh size is about 1 nm to about 5 nm. In some embodiments, the polyurethane matrix may comprise a first polypropylene glycol diol, polypropylene glycol triol, dicyclohexylmethane diisocyanate; and wherein the mesh size is about 5 nm to about 10 nm. In some embodiments, the polyurethane matrix may comprise a first polypropylene glycol diol, a second polypropylene glycol diol, polypropylene glycol triol, dicyclohexylmethane diisocyanate; and wherein the mesh size is about 10 nm to about 40 nm.

[0033] The selection of the first polypropylene glycol diol, the second polypropylene glycol diol, the aliphatic polyisocyanate, the polypropylene glycol triol, the dicyclohexylmethane diisocyanate are not particularly limiting, and one skilled in the artPCT Application 134075-0005WO01 could determine an optimal choice that falls in the scope of the present disclosure. Some non-limiting examples of a polyurethane matrix that can be used in the present holographic photopolymer include a polypropylene glycol triol, such as SANNIX GP-3000 (Sanyo Chemical, Japan), a polypropylene glycol diol, such as SANNIX PA-2000 (Sanyo Chemical, Japan), a dicyclohexylmethane isocyanate, such as Desmodur WP260, (Covestro, Germany), a hexamethylene diisocyanate trimer, such as Desmodur N3600, (Covestro, Germany), an aliphatic isocyanate, such as Desmodur ultra E30600, or a propylene glycol diol, such as Arcol PPG-725 (Covestro, Germany).

[0034] In some embodiments, the holographic photopolymer can comprise about 0.1 g of a polypropylene glycol diol, such as SANNIX PA-2000, about 0.2 g, about 0.25 g, about 0.3 g, about 0.325 g, about 0.35 g, about 0.375 g, about 0.4 g, about 0.425 g, about 0.45 g, about 0.5 g, about 0.55 g, about 0.6 g, about 0.7 g, about 0.8 g, about 0.9 g, about 1.0 g, about 1.1 g, about 1.125 g, about 1.14 g, about 1.15 g, about 1.16 g, about 1.167 g, about 1.175 g, about 1.19 g, about 1.2 g, about 1.3 g, about 1.4 g, about 1.41 g, about 1.42 g, about 1.43 g, about 1.44 g, about 1.45 g, about 1.5 g, about 1.6 g, about 1.7 g, about 1.8 g, about 1.9 g, about 2.0 g, about 2.2 g, about 2.5 g, about 2.75 g, about 3.0 g, about 3.5 g, about 4.0 g, about 4.5 g, about 0.1 g to about 0.2 g, about 0.2 g to about 0.25 g, about 0.25 g to about 0.3 g, about 0.3 g to about 0.325 g, about 0.325 g to about 0.35 g, about 0.35 g to about 0.375 g, about 0.375 g to about 0.4 g, about 0.4 g to about 0.425 g, about 0.425 g to about 0.45 g, about 0.45 g to about 0.5 g, about 0.5 g to about 0.55 g, about 0.55 g to about 0.6 g, about 0.6 g to about 0.7 g, about 0.7 g to about 0.8 g, about 0.8 g to about 0.9 g, about 0.9 g to about 1.0 g, about 1.0 g to about 1.1 g, about 1.1 g to about 1.125 g, about 1.125 g to about 1.14 g, about 1.14 g to about 1.15 g, about 1.15 g to about 1.16 g, about 1.16 g to about 1.167 g, about 1.167 g to about 1.175 g, about 1.175 g to about 1.19 g, about 1.19 g to about 1.2 g, about 1.2 g to about 1.3 g, about 1.3 g to about 1.4 g, about 1.4 g to about 1.41 g, about 1.41 g to about 1.42 g, about 1.42 g to about 1.43 g, about 1.43 g to about 1.44 g, about 1.44 g to about 1.45 g, about 1.45 g to about 1.5 g, about 1.5 g to about 1.6 g, about 1.6 g to about 1.7 g, about 1.7 g to about 1.8 g, about 1.8 g to about 1.9 g, about 1.9 g to about 2.0 g, about 2.0 g to about 2.2 g, about 2.2 g to about 2.5 g, about 2.5 g to about 2.75 g, about 2.75 gPCT Application 134075-0005WO01 to about 3.0 g, about 3.0 g to about 3.5 g, about 3.5 g to about 4.0 g, about 4.0 g to about 4.5 g, about 4.5 g to about 5.0 g, about 5.0 g, or any amount of a polypropylene glycol diol, such as SANNIX PA-2000 bounded by this range. In some embodiments, the holographic photopolymer can comprise about by 15.0% by weight of a polypropylene glycol diol, such as SANNIX PA-2000, about 16.0% by weight, about 16.5% by weight, about 16.7% by weight, about 16.8% by weight, about 16.9% by weight, about 17.0% by weight, about 17.5% by weight, about 18.0% by weight, about 18.5% by weight, about 19.0% by weight, about 19.5% by weight, about 20.0% by weight, about 20.3% by weight, about 20.5% by weight, about 20.6% by weight, about 20.7% by weight, about 20.8% by weight, about 20.9% by weight, about 21.0% by weight, about 22.0% by weight, about 23.0% by weight, about 25% by weight, about 27.5% by weight, about 28.0% by weight, about 29.0% by weight, about 29.5% by weight, about 29.8% by weight, about 29.9% by weight, about 30.0% by weight, about 30.2% by weight, about 30.5% by weight, about 31.0% by weight, about 32.5% by weight, about 15.0% by weight to about 16.0% by weight, about 16.0% by weight to about 17.0% by weight, about 17.0% by weight to about 18.0% by weight, about 18.0% by weight to about 19.0% by weight, about 19.0% by weight to about 20.0% by weight, about 20.0% by weight to about 21.0% by weight, about 21.0% by weight to about 22.0% by weight, about 22.0% by weight to about 23.0% by weight, about 23.0% by weight to about 24.0% by weight, about 25.0% by weight to about 26.0% by weight, about 26.0% by weight to about 27.0% by weight, about 27.0% by weight to about 28.0% by weight, about 28.0% by weight to about 29.0% by weight, about 29.0% by weight to about 30% by weight, about 30.0% by weight to about 31.0% by weight, about 31.0% to about 32% by weight, about 32.0% by weight to about 33% by weight, about 33.0% by weight to about 34.0% by weight, about 34.0% by weight to about 35.0% by weight, about 35.0% by weight, or any amount of a polypropylene glycol diol, such as SANNIX PA-2000 bounded by this range.

[0035] In some embodiments, the holographic photopolymer can comprise about 0.1 g of a polypropylene glycol triol, such as SANNIX GP-3000, about 0.2 g, about 0.25 g, about 0.3 g, about 0.325 g, about 0.35 g, about 0.375 g, about 0.4 g, about 0.425 g, about 0.45 g, about 0.5 g, about 0.55 g, about 0.6 g, about 0.7 g, about 0.8 g, about 0.9PCT Application 134075-0005WO01 g, about 1.0 g, about 1.1 g, about 1.2 g, about 1.3 g, about 1.4 g, about 1.5 g, about 1.6 g, about 1.7 g, about 1.8 g, about 1.9 g, about 2.0 g, about 2.2 g, about 2.5 g, about 2.75 g, about 0.1 g to about 0.2 g, about 0.2 g to about 0.25 g, about 0.25 g to about 0.3 g, about 0.3 g to about 0.325 g, about 0.325 g to about 0.35 g, about 0.35 g to about 0.375 g, about 0.375 g to about 0.4 g, about 0.4 g to about 0.425 g, about 0.425 g to about 0.45 g, about 0.45 g to about 0.5 g, about 0.5 g to about 0.55 g, about 0.55 g to about 0.6 g, about 0.6 g to about 0.7 g, about 0.7 g to about 0.8 g, about 0.8 g to about 0.9 g, about 0.9 g to about 1.0 g, about 1.0 g to about 1.1 g, about 1.1 g to about 1.2 g, about 1.2 g to about 1.3 g, about 1.3 g to about 1.4 g, about 1.4 g to about 1.41 g, about 1.41 g to about 1.42 g, about 1.42 g to about 1.43 g, about 1.43 g to about 1.44 g, about 1.44 g to about 1.45 g, about 1.45 g to about 1.5 g, about 1.5 g to about 1.6 g, about 1.6 g to about 1.7 g, about 1.7 g to about 1.8 g, about 1.8 g to about 1.9 g, about 1.9 g to about 2.0 g, about 2.0 g to about 2.2 g, about 2.2 g to about 2.5 g, about 2.5 g to about 2.75 g, about 2.75 g to about 3.0 g, about 3.0 g, or any amount of a polypropylene glycol triol, such as SANNIX GP-3000 bounded by this range. In some embodiments, the holographic photopolymer can comprise about 7.5% by weight of a polypropylene glycol triol, such as SANNIX GP- 3000, about 7.6% by weight, about 7.7% by weight, about 7.8% by weight, about 7.9% by weight, about 8.0% by weight, about 8.1% by weight, about 8.2% by weight, about 8.3% by weight, about 8.4% by weight, about 8.5% by weight, about 8.6% by weight, about 8.7% by weight, about 8.8% by weight, about 8.9% by weight, about 7.5% by weight to about 7.6% by weight, about 7.6% by weight to about 7.7% by weight, about 7.7% by weight to about 7.8% by weight, about 7.8% by weight to about 7.9% by weight, about 8.0% by weight to about 8.1% by weight, about 8.1% by weight to about 8.2% by weight, about 8.2% by weight to about 8.3% by weight, about 8.3% by weight to about 8.5% by weight, about 8.5% by weight to about 8.7% by weight, about 8.7% by weight to about 8.9% by weight, about 8.9% by weight to about 9.0% by weight, about 9.0% by weight, or any amount of a polypropylene glycol triol, such as SANNIX GP-3000 bounded by this range.

[0036] In some embodiments, the holographic photopolymer can comprise about 0.1 g of a propylene glycol diol, such as SANNIX PP-4000, about 0.2 g, about 0.25 g,PCT Application 134075-0005WO01 about 0.3 g, about 0.325 g, about 0.35 g, about 0.375 g, about 0.4 g, about 0.425 g, about 0.45 g, about 0.5 g, about 0.55 g, about 0.6 g, about 0.7 g, about 0.8 g, about 0.9 g, about 0.95 g, about 1.0 g, about 1.025 g, about 1.05 g, about 1.075 g, about 1.1 g, about 1.125 g, about 1.14 g, about 1.15 g, about 1.16 g, about 1.167 g, about 1.175 g, about 1.19 g, about 1.2 g, about 1.3 g, about 1.4 g, about 1.41 g, about 1.42 g, about 1.43 g, about 1.44 g, about 1.45 g, about 1.5 g, about 1.52 g, about 1.55 g, about 1.56 g, about 1.57 g, about 1.58 g, about 1.585 g, about 1.586 g, about 1.59 g, about 1.6 g, about 1.7 g, about 1.8 g, about 1.9 g, about 2.0 g, about 2.2 g, about 2.5 g, about 2.75 g, about 3.0 g, about 3.5 g, about 4.0 g, about 4.5 g, about 0.1 g to about 0.2 g, about 0.2 g to about 0.25 g, about 0.25 g to about 0.3 g, about 0.3 g to about 0.325 g, about 0.325 g to about 0.35 g, about 0.35 g to about 0.375 g, about 0.375 g to about 0.4 g, about 0.4 g to about 0.425 g, about 0.425 g to about 0.45 g, about 0.45 g to about 0.5 g, about 0.5 g to about 0.55 g, about 0.55 g to about 0.6 g, about 0.6 g to about 0.7 g, about 0.7 g to about 0.8 g, about 0.8 g to about 0.9 g, about 0.9 g to about 1.0 g, about 1.0 g to about 1.1 g, about 1.1 g to about 1.2 g, about 1.2 g to about 1.3 g, about 1.3 g to about 1.4 g, about 1.4 g to about 1.41 g, about 1.41 g to about 1.42 g, about 1.42 g to about 1.43 g, about 1.43 g to about 1.44 g, about 1.44 g to about 1.45 g, about 1.45 g to about 1.5 g, about 1.5 g to about 1.6 g, about 1.6 g to about 1.7 g, about 1.7 g to about 1.8 g, about 1.8 g to about 1.9 g, about 1.9 g to about 2.0 g, about 2.0 g to about 2.2 g, about 2.2 g to about 2.5 g, about 2.5 g to about 2.75 g, about 2.75 g to about 3.0 g, about 3.0 g to about 3.5 g, about 3.5 g to about 4.0 g, about 4.0 g to about 4.5 g, about 4.5 g to about 5.0 g, about 5.0 g, or any amount of a propylene glycol diol, such as SANNIX PP-4000 bounded by this range. In some embodiments, the holographic photopolymer can comprise about 20.0% by weight of a propylene glycol diol, such as SANNIX PP-4000, about 20.5% by weight, about 20.6% by weight, about 20.7% by weight, about 20.8% by weight, about 20.9% by weight, about 21.0% by weight, about 21.1% by weight, about 21.2% by weight, about 21.5% by weight, about 22.0% by weight, about 23.0% by weight, about 24.0% by weight, about 25.0% by weight, about 26.0% by weight, about 27.0% by weight, about 27.5% by weight, about 27.6% by weight, about 27.7% by weight, about 27.8% by weight, about 27.9% by weight, about 28.0% by weight, about 28.1% by weight, about 28.2% by weight, about 28.5% byPCT Application 134075-0005WO01 weight, about 29.0% by weight, about 20.0% by weight to about 21.0% by weight, about 21.0% by weight to about 22.0% by weight, about 22.0% by weight to about 23.0% by weight, about 23.0% by weight to about 24.0% by weight, about 25.0% by weight to about 26.0% by weight, about 26.0% by weight to about 27.0% by weight, about 27.0% by weight to about 28.0% by weight, about 28.0% by weight to about 29.0% by weight, about 29.0% by weight to about 30% by weight, about 30.0% by weight, or any amount of a propylene glycol diol, such as SANNIX PP-4000 bounded by this range.

[0037] In some embodiments, the holographic photopolymer can comprise about 0.1 g of a dicyclohexylmethane isocyanate, such as Desmodur WP260, about 0.2 g, about 0.25 g, about 0.3 g, about 0.325 g, about 0.33 g, about 0.34 g, about 0.35 g, about 0.375 g, about 0.38 g, about 0.39 g, about 0.4 g, about 0.41 g, about 0.425 g, about 0.45 g, about 0.5 g, about 0.55 g, about 0.6 g, about 0.7 g, about 0.8 g, about 0.9 g, about 1.0 g, about 1.1 g, about 1.2 g, about 1.3 g, about 1.4 g, about 1.5 g, about 1.6 g, about 1.7 g, about 1.8 g, about 1.9 g, about 2.0 g, about 2.2 g, about 2.5 g, about 2.75 g, about 0.1 g to about 0.2 g, about 0.2 g to about 0.25 g, about 0.25 g to about 0.3 g, about 0.3 g to about 0.325 g, about 0.325 g to about 0.35 g, about 0.35 g to about 0.375 g, about 0.375 g to about 0.4 g, about 0.4 g to about 0.425 g, about 0.425 g to about 0.45 g, about 0.45 g to about 0.5 g, about 0.5 g to about 0.55 g, about 0.55 g to about 0.6 g, about 0.6 g to about 0.7 g, about 0.7 g to about 0.8 g, about 0.8 g to about 0.9 g, about 0.9 g to about 1.0 g, about 1.0 g to about 1.1 g, about 1.1 g to about 1.2 g, about 1.2 g to about 1.3 g, about 1.3 g to about 1.4 g, about 1.4 g to about 1.41 g, about 1.41 g to about 1.42 g, about 1.42 g to about 1.43 g, about 1.43 g to about 1.44 g, about 1.44 g to about 1.45 g, about 1.45 g to about 1.5 g, about 1.5 g to about 1.6 g, about 1.6 g to about 1.7 g, about 1.7 g to about 1.8 g, about 1.8 g to about 1.9 g, about 1.9 g to about 2.0 g, about 2.0 g to about 2.2 g, about 2.2 g to about 2.5 g, about 2.5 g to about 2.75 g, about 2.75 g to about 3.0 g, about 3.0 g, or any amount of a dicyclohexylmethane isocyanate, such as Desmodur WP260 bounded by this range. In some embodiments, the holographic photopolymer can comprise about 7.0% by weight of a dicyclohexylmethane isocyanate, such as Desmodur WP260, about 7.1% by weight, about 7.2% by weight, about 7.3% by weight, about 7.4% by weight, about 7.5% by weight, about 7.6% by weight, about 7.7%PCT Application 134075-0005WO01 by weight, about 7.8% by weight, about 7.9% by weight, about 8.0% by weight, about 8.1% by weight, about 8.2% by weight, about 8.3% by weight, about 7.0% by weight to about 7.1% by weight, about 7.1% by weight to about 7.2% by weight, about 7.2% by weight to about 7.3% by weight, about 7.3% by weight to about 7.4% by weight, about 7.4% by weight to about 7.5% by weight, about 7.5% by weight to about 7.6% by weight, about 7.6% by weight to about 7.7% by weight, about 7.7% by weight to about 7.8% by weight, about 7.8% by weight to about 7.9% by weight, about 8.0% by weight to about 8.1% by weight, about 8.1% by weight to about 8.2% by weight, about 8.2% by weight to about 8.3% by weight, about 8.3% by weight to about 8.5% by weight, about 8.5% by weight, or any amount of a dicyclohexylmethane isocyanate, such as Desmodur WP260 bounded by this range.

[0038] In some embodiments, the holographic photopolymer can comprise about 0.1 g of a hexamethylene diisocyanate trimer, such as Desmodur N3600, about 0.2 g, about 0.25 g, about 0.3 g, about 0.325 g, about 0.33 g, about 0.34 g, about 0.35 g, about 0.375 g, about 0.38 g, about 0.39 g, about 0.4 g, about 0.41 g, about 0.425 g, about 0.45 g, about 0.5 g, about 0.55 g, about 0.6 g, about 0.7 g, about 0.8 g, about 0.9 g, about 1.0 g, about 1.1 g, about 1.2 g, about 1.3 g, about 1.4 g, about 1.5 g, about 1.6 g, about 1.7 g, about 1.8 g, about 1.9 g, about 2.0 g, about 2.2 g, about 2.5 g, about 2.75 g, about 0.1 g to about 0.2 g, about 0.2 g to about 0.25 g, about 0.25 g to about 0.3 g, about 0.3 g to about 0.325 g, about 0.325 g to about 0.35 g, about 0.35 g to about 0.375 g, about 0.375 g to about 0.4 g, about 0.4 g to about 0.425 g, about 0.425 g to about 0.45 g, about 0.45 g to about 0.5 g, about 0.5 g to about 0.55 g, about 0.55 g to about 0.6 g, about 0.6 g to about 0.7 g, about 0.7 g to about 0.8 g, about 0.8 g to about 0.9 g, about 0.9 g to about 1.0 g, about 1.0 g to about 1.1 g, about 1.1 g to about 1.2 g, about 1.2 g to about 1.3 g, about 1.3 g to about 1.4 g, about 1.4 g to about 1.41 g, about 1.41 g to about 1.42 g, about 1.42 g to about 1.43 g, about 1.43 g to about 1.44 g, about 1.44 g to about 1.45 g, about 1.45 g to about 1.5 g, about 1.5 g to about 1.6 g, about 1.6 g to about 1.7 g, about 1.7 g to about 1.8 g, about 1.8 g to about 1.9 g, about 1.9 g to about 2.0 g, about 2.0 g to about 2.2 g, about 2.2 g to about 2.5 g, about 2.5 g to about 2.75 g, about 2.75 g to about 3.0 g, about 3.0 g, or any amount of a hexamethylene diisocyanate trimer, such asPCT Application 134075-0005WO01 Desmodur N3600 bounded by this range. In some embodiments, the holographic photopolymer can comprise about 6.5% by weight of a hexamethylene diisocyanate trimer, such as Desmodur N3600, about 6.6% by weight, about 6.7% by weight, about 6.8% by weight, about 6.9% by weight, about 7.0% by weight, about 7.1% by weight, about 7.2% by weight, about 7.3% by weight, about 7.4% by weight, about 6.5% by weight to about 6.6% by weight, about 6.6% by weight to about 6.7% by weight, about 6.7% by weight to about 6.8% by weight, about 6.8% by weight to about 6.9% by weight, about 6.9% by weight to about 7.0% by weight, about 7.0% by weight to about 7.1% by weight, about 7.1% by weight to about 7.2% by weight, about 7.2% by weight to about 7.3% by weight, about 7.3% by weight to about 7.4% by weight, about 7.4% by weight to about 7.5% by weight, about 7.5% by weight, or any amount of a hexamethylene diisocyanate trimer, such as Desmodur N3600 bounded by this range.

[0039] In some embodiments, the holographic photopolymer can comprise about 0.1 g of an aliphatic isocyanate, such as Desmodur ultra E30600, about 0.2 g, about 0.25 g, about 0.3 g, about 0.325 g, about 0.33 g, about 0.335 g, about 0.34 g, about 0.345 g, about 0.35 g, about 0.36 g, about 0.375 g, about 0.38 g, about 0.39 g, about 0.4 g, about 0.41 g, about 0.425 g, about 0.45 g, about 0.5 g, about 0.525 g, about 0.53 g, about 0.535 g, about 0.538 g, about 0.54 g, about 0.55 g, about 0.56 g, about 0.57 g, about 0.58 g, about 0.59 g, about 0.6 g, about 0.65 g, about 0.7 g, about 0.8 g, about 0.82 g, about 0.833 g, about 0.85 g, about 0.875 g, about 0.9 g, about 1.0 g, about 1.1 g, about 1.2 g, about 1.3 g, about 1.4 g, about 1.5 g, about 1.6 g, about 1.7 g, about 1.8 g, about 1.9 g, about 2.0 g, about 2.2 g, about 2.5 g, about 2.75 g, about 0.1 g to about 0.2 g, about 0.2 g to about 0.25 g, about 0.25 g to about 0.3 g, about 0.3 g to about 0.325 g, about 0.325 g to about 0.35 g, about 0.35 g to about 0.375 g, about 0.375 g to about 0.4 g, about 0.4 g to about 0.425 g, about 0.425 g to about 0.45 g, about 0.45 g to about 0.5 g, about 0.5 g to about 0.55 g, about 0.55 g to about 0.6 g, about 0.6 g to about 0.7 g, about 0.7 g to about 0.8 g, about 0.8 g to about 0.9 g, about 0.9 g to about 1.0 g, about 1.0 g to about 1.1 g, about 1.1 g to about 1.2 g, about 1.2 g to about 1.3 g, about 1.3 g to about 1.4 g, about 1.4 g to about 1.41 g, about 1.41 g to about 1.42 g, about 1.42 g to about 1.43 g, about 1.43 g to about 1.44 g, about 1.44 g to about 1.45 g, about 1.45 g to about 1.5 g,PCT Application 134075-0005WO01 about 1.5 g to about 1.6 g, about 1.6 g to about 1.7 g, about 1.7 g to about 1.8 g, about 1.8 g to about 1.9 g, about 1.9 g to about 2.0 g, about 2.0 g to about 2.2 g, about 2.2 g to about 2.5 g, about 2.5 g to about 2.75 g, about 2.75 g to about 3.0 g, about 3.0 g, or any amount of an aliphatic isocyanate, such as Desmodur ultra E30600 bounded by this range. In some embodiments, the holographic photopolymer can comprise about 6.0% by weight of an aliphatic isocyanate, such as Desmodur ultra E30600, about 6.5% by weight, about 6.75% by weight, about 7.0% by weight, about 7.1% by weight, about 7.2% by weight, about 7.3% by weight, about 7.4% by weight, about 7.5% by weight, about 7.6% by weight, about 7.7% by weight, about 7.8% by weight, about 7.9% by weight, about 8.0% by weight, about 8.5% by weight, about 9.0% by weight, about 9.35% by weight, about 9.4% by weight, about 9.5% by weight, about 9.6% by weight, about 9.75% by weight, about 10.0% by weight, about 11.0% by weight, about 12.0% by weight, about 13.0% by weight, about 14.0% by weight, about 14.5% by weight, about 14.7% by weight, about 14.9% by weight, about 15.0% by weight, about 16.0% by weight, about 18.0% by weight, about 6.0% by weight to about 7.0% by weight, about 7.0% by weight to about 8.0% by weight, about 8.0% by weight to about 9.0% by weight, about 9.0% by weight to about 10.0% by weight, about 10.0% by weight to about 11.0% by weight, about 11.0% by weight to about 12.0% by weight, about 12.0% by weight to about 13.0% by weight, about 14.0% by weight to about 15.0% by weight, about 15.0% by weight to about 16.0% by weight, about 16.0% by weight to about 17.0% by weight, about 17.0% by weight to about 18.0% by weight, about 18.0% by weight to about 20.0% by weight, about 20.0% by weight, or any amount of an aliphatic isocyanate, such as Desmodur ultra E30600 bounded by this range.

[0040] In some embodiments, the holographic photopolymer can comprise about 0.05 g of a propylene glycol diol, such as Arcol PPG-725, about 0.06 g, about 0.07 g, about 0.08 g, about 0.09 g, about 0.1 g, about 0.12 g, about 0.14 g, about 0.15 g, about 0.175 g, about 0.2 g, about 0.25 g, about 0.3 g, about 0.325 g, about 0.34 g, about 0.35 g, about 0.375 g, about 0.38 g, about 0.39 g, about 0.4 g, about 0.41 g, about 0.425 g, about 0.45 g, about 0.5 g, about 0.55 g, about 0.6 g, about 0.7 g, about 0.8 g, about 0.9 g, about 1.0 g, about 1.1 g, about 1.2 g, about 1.3 g, about 1.4 g, about 1.5 g, about 1.6PCT Application 134075-0005WO01 g, about 1.7 g, about 1.8 g, about 1.9 g, about 2.0 g, about 2.2 g, about 2.5 g, about 2.75 g, about 0.05 g to about 0.06 g, about 0.06 g to about 0.07 g, about 0.07 g to about 0.08 g, about 0.08 g to about 0.09 g, about 0.09 g to about 0.1 g, about 0.1 g to about 0.2 g, about 0.2 g to about 0.25 g, about 0.25 g to about 0.3 g, about 0.3 g to about 0.325 g, about 0.325 g to about 0.35 g, about 0.35 g to about 0.375 g, about 0.375 g to about 0.4 g, about 0.4 g to about 0.425 g, about 0.425 g to about 0.45 g, about 0.45 g to about 0.5 g, about 0.5 g to about 0.55 g, about 0.55 g to about 0.6 g, about 0.6 g to about 0.7 g, about 0.7 g to about 0.8 g, about 0.8 g to about 0.9 g, about 0.9 g to about 1.0 g, about 1.0 g to about 1.1 g, about 1.1 g to about 1.2 g, about 1.2 g to about 1.3 g, about 1.3 g to about 1.4 g, about 1.4 g to about 1.41 g, about 1.41 g to about 1.42 g, about 1.42 g to about 1.43 g, about 1.43 g to about 1.44 g, about 1.44 g to about 1.45 g, about 1.45 g to about 1.5 g, about 1.5 g to about 1.6 g, about 1.6 g to about 1.7 g, about 1.7 g to about 1.8 g, about 1.8 g to about 1.9 g, about 1.9 g to about 2.0 g, about 2.0 g to about 2.2 g, about 2.2 g to about 2.5 g, about 2.5 g to about 2.75 g, about 2.75 g to about 3.0 g, about 3.0 g, or any amount of a propylene glycol diol, such as Arcol PPG-725 bounded by this range. In some embodiments, the holographic photopolymer can comprise about 3.0% by weight of a propylene glycol diol, such as Arcol PPG-725, about 3.5% by weight, about 3.7% by weight, about 4.0% by weight, about 4.1% by weight, about 4.2% by weight, about 4.3% by weight, about 4.4% by weight, about 4.5% by weight, about 4.6% by weight, about 4.7% by weight, about 4.8% by weight, about 4.9% by weight, about 3.0% by weight to about 3.5% by weight, about 3.5% by weight to about 4.0% by weight, about 4.0% by weight to about 4.2% by weight, about 4.2% by weight to about 4.4% by weight, about 4.4% by weight to about 4.6% by weight, about 4.6% by weight to about 4.8% by weight, about 4.8% by weight to about 5.0Y by weight, about 5.0% by weight, or any amount of a propylene glycol diol, such as Arcol PPG-725 bounded by this range.

[0041] In some embodiments, the holographic photopolymer can comprise about 0.01 g of 10% tin catalyst, about 0.02 g, about 0.025 g, about 0.03 g, about 0.031 g, about 0.032 g, about 0.0325 g, about 0.035 g, about 0.0375 g, about 0.04 g, about 0.0425 g, about 0.045 g, about 0.05 g, about 0.055 g, about 0.06 g, about 0.065 g, about 0.07 g, about 0.08 g, about 0.09 g, about 0.1 g, about 0.11 g, about 0.12 g, about 0.13 g, aboutPCT Application 134075-0005WO01 0.14 g, about 0.15 g, about 0.16 g, about 0.17 g, about 0.18 g, about 0.19 g, about 0.2 g, about 0.22 g, about 0.25 g, about 0.275 g, about 0.01 g to about 0.02 g, about 0.02 g to about 0.025 g, about 0.025 g to about 0.03 g, about 0.03 g to about 0.035 g, 0.035 g to about 0.04 g, about 0.04 g to about 0.045 g, about 0.045 g to about 0.05 g, about 0.05 g to about 0.055 g, about 0.055 g to about 0.06 g, about 0.06 g to about 0.07 g, about 0.07 g to about 0.08 g, about 0.08 g to about 0.09 g, about 0.09 g to about 0.1 g, about 0.1 g to about 0.11 g, 0.11 g to about 0.13 g, about 0.13 g to about 0.15 g, about 0.15 g to about 0.17 g, about 0.17 g to about 0.19 g, 0.19 g to about 0.2 g, about 0.2 g to about 0.22 g, about 0.22 g to about 0.25 g, about 0.25 g to about 0.3 g, about 0.3 g, or any amount of 10% tin catalyst bounded by this range. In some embodiments, the holographic photopolymer can comprise about 0.50% by weight of 10% tin catalyst, about 0.60% by weight, about 0.70% by weight, about 0.80% by weight, about 0.90% by weight, about 1.0% by weight, about 1.1% by weight, about 1.2% by weight, about 1.3% by weight, about 1.4% by weight, about 1.5% by weight, about 1.6% by weight, about 1.7% by weight, about 1.8% by weight, about 1.9% by weight, about 2.0% by weight, about 0.5% by weight to about 0.7 % by weight, about 0.7% by weight to about 0.9% by weight, about 0.9% by weight to about 1,1% by weight, about 1.1% by weight to about 1.3% by weight, about 1.3% by weight to about 1.5% by weight, about 1.5% by weight to about 1.7% by weight, about 1.7% by weight to about 2.0% by weight, about 2.0% by weight to about 2.2% by weight, about 2.2% by weight to about 2.5% by weight, about 2.5% by weight, or any amount of 10% tin catalyst bounded by this range.

[0042] In some embodiments, the holographic photopolymer can comprise about 0.05 g of Bis(butylcarbitol)formal, about 0.06 g, about 0.07 g, about 0.08 g, about 0.09 g, about 0.1 g, about 0.12 g, about 0.14 g, about 0.15 g, about 0.175 g, about 0.2 g, about 0.25 g, about 0.3 g, about 0.325 g, about 0.34 g, about 0.35 g, about 0.375 g, about 0.38 g, about 0.39 g, about 0.4 g, about 0.41 g, about 0.425 g, about 0.45 g, about 0.5 g, about 0.55 g, about 0.6 g, about 0.7 g, about 0.8 g, about 0.9 g, about 1.0 g, about 1.1 g, about 1.2 g, about 1.3 g, about 1.4 g, about 1.5 g, about 1.6 g, about 1.7 g, about 1.8 g, about 1.9 g, about 2.0 g, about 2.2 g, about 2.5 g, about 2.75 g, about 0.05 g to about 0.06 g, about 0.06 g to about 0.07 g, about 0.07 g to about 0.08 g, about 0.08 g to about 0.09 g,PCT Application 134075-0005WO01 about 0.09 g to about 0.1 g, about 0.1 g to about 0.2 g, about 0.2 g to about 0.25 g, about 0.25 g to about 0.3 g, about 0.3 g to about 0.325 g, about 0.325 g to about 0.35 g, about 0.35 g to about 0.375 g, about 0.375 g to about 0.4 g, about 0.4 g to about 0.425 g, about 0.425 g to about 0.45 g, about 0.45 g to about 0.5 g, about 0.5 g to about 0.55 g, about 0.55 g to about 0.6 g, about 0.6 g to about 0.7 g, about 0.7 g to about 0.8 g, about 0.8 g to about 0.9 g, about 0.9 g to about 1.0 g, about 1.0 g to about 1.1 g, about 1.1 g to about 1.2 g, about 1.2 g to about 1.3 g, about 1.3 g to about 1.4 g, about 1.4 g to about 1.41 g, about 1.41 g to about 1.42 g, about 1.42 g to about 1.43 g, about 1.43 g to about 1.44 g, about 1.44 g to about 1.45 g, about 1.45 g to about 1.5 g, about 1.5 g to about 1.6 g, about 1.6 g to about 1.7 g, about 1.7 g to about 1.8 g, about 1.8 g to about 1.9 g, about 1.9 g to about 2.0 g, about 2.0 g to about 2.2 g, about 2.2 g to about 2.5 g, about 2.5 g to about 2.75 g, about 2.75 g to about 3.0 g, about 3.0 g, or any amount of Bis(butylcarbitol)formal bounded by this range. In some embodiments, the holographic photopolymer can comprise about 6.0% by weight of Bis(butylcarbitol)formal, about 6.5% by weight, about 6.75% by weight, about 7.0% by weight, about 7.1% by weight, about 7.2% by weight, about 7.3% by weight, about 7.4% by weight, about 7.5% by weight, about 7.6% by weight, about 7.7% by weight, about 7.8% by weight, about 7.9% by weight, about 8.0% by weight, about 8.1% by weight, about 8.2% by weight, about 8.3% by weight, about 8.5% by weight, about 8.6% by weight, about 8.7% by weight, about 8.8% by weight, about 8.9% by weight, about 9.0% by weight, about 9.1% by weight, about 9.35% by weight, about 9.4% by weight, about 9.5% by weight, about 9.6% by weight, about 9.75% by weight, about 10.0% by weight, about 11.0% by weight, about 6.0% by weight to about 7.0% by weight, about 7.0% by weight to about 8.0% by weight, about 8.0% by weight to about 9.0% by weight, about 9.0% by weight to about 10.0% by weight, about 10% by weight to about 12% by weight, about 12.0% by weight, or any amount of Bis(butylcarbitol)formal bounded by this range.

[0043] In some embodiments, the holographic photopolymer can comprise about 0.05 g of triethylene glycol Bis (2-ethylhexanoate), about 0.06 g, about 0.07 g, about 0.08 g, about 0.09 g, about 0.1 g, about 0.12 g, about 0.14 g, about 0.15 g, about 0.175 g, about 0.2 g, about 0.25 g, about 0.3 g, about 0.325 g, about 0.34 g, about 0.35 g, aboutPCT Application 134075-0005WO01 0.375 g, about 0.38 g, about 0.39 g, about 0.4 g, about 0.41 g, about 0.425 g, about 0.45 g, about 0.5 g, about 0.55 g, about 0.6 g, about 0.7 g, about 0.8 g, about 0.9 g, about 1.0 g, about 1.1 g, about 1.2 g, about 1.3 g, about 1.4 g, about 1.5 g, about 1.6 g, about 1.7 g, about 1.8 g, about 1.9 g, about 2.0 g, about 2.2 g, about 2.5 g, about 2.75 g, about 0.05 g to about 0.06 g, about 0.06 g to about 0.07 g, about 0.07 g to about 0.08 g, about 0.08 g to about 0.09 g, about 0.09 g to about 0.1 g, about 0.1 g to about 0.2 g, about 0.2 g to about 0.25 g, about 0.25 g to about 0.3 g, about 0.3 g to about 0.325 g, about 0.325 g to about 0.35 g, about 0.35 g to about 0.375 g, about 0.375 g to about 0.4 g, about 0.4 g to about 0.425 g, about 0.425 g to about 0.45 g, about 0.45 g to about 0.5 g, about 0.5 g to about 0.55 g, about 0.55 g to about 0.6 g, about 0.6 g to about 0.7 g, about 0.7 g to about 0.8 g, about 0.8 g to about 0.9 g, about 0.9 g to about 1.0 g, about 1.0 g to about 1.1 g, about 1.1 g to about 1.2 g, about 1.2 g to about 1.3 g, about 1.3 g to about 1.4 g, about 1.4 g to about 1.41 g, about 1.41 g to about 1.42 g, about 1.42 g to about 1.43 g, about 1.43 g to about 1.44 g, about 1.44 g to about 1.45 g, about 1.45 g to about 1.5 g, about 1.5 g to about 1.6 g, about 1.6 g to about 1.7 g, about 1.7 g to about 1.8 g, about 1.8 g to about 1.9 g, about 1.9 g to about 2.0 g, about 2.0 g to about 2.2 g, about 2.2 g to about 2.5 g, about 2.5 g to about 2.75 g, about 2.75 g to about 3.0 g, about 3.0 g, or any amount of triethylene glycol Bis (2-ethylhexanoate) bounded by this range. In some embodiments, the holographic photopolymer can comprise about 5.0% by weight of triethylene glycol Bis (2-ethylhexanoate), about 5.5% by weight, about 5.75% by weight, about 6.0% by weight, about 6.2% by weight, about 6.4% by weight, about 6.5% by weight, about 6.6% by weight, about 6.7% by weight, about 6.75% by weight, about 6.8% by weight, about 6.9% by weight, about 7.0% by weight, about 7.1% by weight, about 7.2% by weight, about 7.3% by weight, about 7.4% by weight, about 7.5% by weight, about 7.6% by weight, about 7.7% by weight, about 7.8% by weight, about 7.9% by weight, about 8.0% by weight, about 8.1% by weight, about 8.2% by weight, about 8.3% by weight, about 8.5% by weight, about 8.6% by weight, about 8.7% by weight, about 8.8% by weight, about 8.9% by weight, about 9.0% by weight, about 9.1% by weight, about 9.4% by weight, about 9.5% by weight, about 9.75% by weight, about 5.0% by weight to about 6.0% by weight, about 6.0% by weight to about 7.0% by weight, about 7.0% by weight toPCT Application 134075-0005WO01 about 8.0% by weight, about 8.0% by weight to about 9.0% by weight, about 9.0% by weight to about 10.0% by weight, about 10.0% by weight, or any amount of triethylene glycol Bis (2-ethylhexanoate) bounded by this range.

[0044] In some embodiments, the weight percent of the polyurethane matrix to the writing monomer can be greater than about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, or about 95%. In some embodiments, the polyurethane matrix may have a free volume, i.e., there is an unoccupied space between the molecules. It is believed that a polyurethane matrix having more free volume decreases the storage modulus and increases the mesh size, and thus improves the diffusivity of the writing monomer.

[0045] In some embodiments, the polyurethane matrix may further comprise a liquid additive. In some embodiments, the liquid additive may comprise a plasticizer. In some embodiments, the liquid additive may comprise ethylene glycol units, propylene glycol units, cyclohexane ester units, or a combination thereof. In some embodiments, the ethylene glycol units, the propylene glycol units, and / or the cyclohexane ester units are similar or the same as the ethylene glycol units, the propylene glycol units, and / or the cyclohexane ester units of the polyurethane matrix. In some embodiments, the liquid additive may comprise: , wherein n is about 1 to about 4, wherein R1and / or R2can beabout 1 to about 20 carbon atoms. In some embodiments, the liquid additive may comprise: , wherein R1 and / or R2 can be an alkyl group comprising about 1 to aboutIn some embodiments, the liquid additive may comprise:PCT Application 134075-0005WO01 , wherein R1 and / or R2 can be an alkyl group comprising about 1 toIn some embodiments, the liquid additive may comprise: O R1 O OR On O 2n, wherein n is about 1 to about 4, wherein R1comprising about 1 to about 20 carbon atoms. In some embodiments, the liquid additive may comprise: n R1 O OR On O 2nwherein n is about 1 to about 4, wherein R1and / or R2about 1 to about 20 carbon atoms.

[0046] The selection of the liquid additive is not particularly limiting, and one skilled in the art could determine an optimal choice that falls in the scope of the present disclosure. Some non-limiting examples of a liquid additive that can be used in the present holographic photopolymer include Efka PL 5651 (bis(butylcarbitol)formal) (CAS 143-29- 3) (BASF, China) or triethylene glycol bis (2-ethylhexanoate) (CAS 94-28-0) (Eastman, Netherlands). It is believed that a liquid additive improves the refractive index and transmission is improved to greater than 90%.

[0047] In some embodiments, the holographic photopolymer may comprise a writing monomer and a dye system. In some embodiments, the holographic photopolymer may comprise a polycyclic writing monomer. In some embodiments, the polycyclic writing monomer may comprise a difunctional writing monomer or a monofunctional writing monomer. In some embodiments, the polycyclic writing monomer may comprise ethoxylated bisphenol a diacrylate, ethoxylated fluorene diacrylate, m-phenoxybenzyl acrylate, biphenylmethyl acrylate, or a combination thereof.

[0048] The writing monomer is not particularly limiting, and one skilled in the art could determine an optimal choice of a writing monomer to use that falls in the scope of the present disclosure. Some non-limiting examples of a writing monomer that can be used in the present holographic photopolymer include EA-F5710 (Osaka Gas Chemicals,PCT Application 134075-0005WO01 Japan), MIRAMER M1197 (MIWON, Korea) and / or SR349 (Sartomer, United States). In some embodiments, the ratio of the EA-F5710 to the MIRAMER M1197 to the SR349 can be about 3:0.5:0.5 to about 6:1.5:1.5, or any ratio bounded by this range. In some embodiments, the ratio of a fluorinated acrylic copolymer, such as EA-F5710, to a methacrylate monomer, such as MIRAMER M1197, to a bisphenol A diacrylate, such as SR349, can be about 6:0.5:0.5, about 6:0.6:0.6, about 6:0.7:0.7, about 6:0.8:0.8, about 6:0.9:0.9, about 6:1:1, about 6:1.1:1.1; about 6:1.2:1.2; about 6:1.3:1.3; about 6:1.4:1.4; about 6:1.5:1.5, about 6:1.6:1.6; about 6:1.7:1.7; about 6:1.8:1.8; about 6:1.9:1.9, about 6:2:2, about 6:0.5:0.5 to 6:0.6:0.6, about 6:0.6:0.6 to 6:0.7:0.7, about 6:0.7:0.7 to about 6:0.8:0.8, about 6:0.8:0.8 to about 6:0.9:0.9, about 6:0.9:0.9 to about 6:1:1, about 6:1:1 to about 6:1.1:1.1, about 6:1.1:1.1 to about 6:1.2:1.2; about 6:1.2:1.2 to about 6:1.3:1.3; about 6:1.3:1.3 to about 6:1.4:1.4; about 6:1.4:1.4 to about 6:1.5:1.5; about 6:1.5:1.5 to about 6:1.6:1.6, about 6:1.6:1.6 to about 6:1.7:1.7; about 6:1.7:1.7 to about 6:1.8:1.8; about 6:1.8:1.8 to about 6:1.9:1.9; about 6:1.9:1.9 to about 6:2:2, or any ratio of a fluorinated acrylic copolymer, such as EA-F5710, to a methacrylate monomer, such as MIRAMER M1197, to a bisphenol A diacrylate, such as SR349, bounded by this range.

[0049] In some embodiments, the holographic photopolymer can comprise about 1.0 g of a fluorinated acrylic copolymer, such as EA-F5710, about 1.1 g, about 1.2 g, about 1.3 g, about 1.4 g, about 1.5 g, about 1.6 g, about 1.65 g, about 1.7 g, about 1.75 g, about 1.8 g, about 1.85 g, about 1.9 g, about 2.0 g, about 2.1 g, about 2.2 g, about 2.5 g, about 3.0 g, about 1.0-1.1 g, about 1.1-1.2 g, about 1.2-1.3 g, about 1.3-1.4 g, about 1.4-1.5 g, about 1.5-1.6 g, about 1.6-1.65 g, about 1.65-1.7 g, about 1.7-1.75 g, about 1.75-1.8 g, about 1.8-1.85 g, about 1.85-1.9 g, about 1.9-2 g, about 2.0-2.1 g, about 2.1- 2.2 g, about 2.2-2.5 g, about 2.5-3 g, about 3.0 g, or any amount of a fluorinated acrylic copolymer, such as EA-F5710 bounded by this range. In some embodiments, the holographic photopolymer can comprise about 25% by weight of a fluorinated acrylic copolymer, such as EA-F5710, about 27% by weight, about 28% by weight, about 28.5% by weight, about 29.0% by weight, about 29.5% by weight, about 30% by weight, about 30.50% by weight, about 30.75% by weight, about 30.84% by weight, about 30.86% by weight, about 31.0% by weight, about 31.5% by weight, about 32.0% by weight, aboutPCT Application 134075-0005WO01 32.5% by weight, about 33% by weight, about 33.1% by weight, about 33.2% by weight, about 33.3% by weight, about 33.5% by weight, about 33.7% by weight, about 33.8% by weight, about 33.9% by weight, about 34.0% by weight, about 34.1% by weight, about 34.125% by weight, about 34.15% by weight, about 34.17% by weight, about 34.2% by weight, about 34.24% by weight, about 34.25% by weight, about 34.29% by weight, about 34.3% by weight, about 34.4% by weight, about 34.5% by weight, about 35% by weight, about 35.23% by weight, about 35.5% by weight, about 35.57% by weight, about 35.6% by weight, about 35.575% by weight, about 36% by weight, about 36.2%, about 36.3% by weight, about 36.53% by weight, about 36.6% by weight, about 36.7% by weight, about 36.76% by weight, about 36.82% by weight, about 36.84% by weight, about 36.875% by weight, about 36.90% by weight, about 37.0% by weight, about 37.5% by weight, about 38.0% by weight, about 39.0% by weight, about 25.0% by weight to about 26% by weight, about 26.0% by weight to about 27.0% by weight, about 27% by weight to about 28% by weight, about 28.0% by weight to about 29.0% by weight, about 29.0% by weight to about 30% by weight, about 30.0% by weight to about 31.0% by weight, about 31.0% by weight to about 32.0% by weight, about 32.0% by weight to about 33.0% by weight, about 33.0% by weight to about 34% by weight, about 34.0% by weight to about 35.0% by weight, about 35.0% by weight to about 36.0% by weight, about 36.0% by weight to about 37.0% by weight, about 37.0% by weight to about 37.5% by weight, about 37.5% by weight to about 38.0% by weight, about 38.0% by weight to about 39.0% by weight, about 39.0% by weight to about 40.0% by weight, about 40.0% by weight, or any amount of a fluorinated acrylic copolymer, such as EA-F5710 bounded by this range.

[0050] In some embodiments, the holographic photopolymer can comprise about 0.1 g of a methacrylate monomer, such as MIRAMER M1197, about 0.2 g, about 0.25 g, about 0.3 g, about 0.325 g, about 0.35 g, about 0.375 g, about 0.4 g, about 0.425 g, about 0.45 g, about 0.5 g, about 0.55 g, about 0.6 g, about 0.7 g, about 0.8 g, about 0.9 g, about 1.0 g, about 1.1 g, about 1.2 g, about 1.3 g, about 1.4 g, about 0.1 g to about 0.2 g, about 0.2 g to about 0.3 g, about 0.3 g to about 0.4 g, about 0.4 g to about 0.5 g, about 0.5 g to about 0.6 g, about 0.6 g to about 0.7 g, about 0.7 g to about 0.8 g, about 0.8 g to about 0.9 g, about 0.9 g to about 1.0 g, about 1.0 g to about 1.1 g, about 1.1 g to about 1.2 g,PCT Application 134075-0005WO01 about 1.2 g to about 1.3 g, about 1.3 g to about 1.4 g, about 1.4 g to about 1.5 g, about 1.5 g, or any amount of a methacrylate monomer, such as MIRAMER M1197 bounded by this range. In some embodiments, the holographic photopolymer can comprise about 5.0% by weight of a methacrylate monomer, such as MIRAMER M1197, about 6.0% by weight, about 6.1% by weight, about 6.20% by weight, about 6.25% by weight, about 6.275% by weight, about 6.3% by weight, about 6.5% by weight, about 6.6% by weight, about 6.61% by weight, about 6.62% by weight, about 6.65% by weight, about 6.75% by weight, about 7% by weight, about 7.05% by weight, about 7.10% by weight, about 7.15% by weight, about 7.2% by weight, about 7.25% by weight, about 7.28% by weight, about 7.3% by weight, about 7.31% by weight, about 7.32% by weight, about 7.33% by weight, about 7.35% by weight, about 7.4% by weight, about 7.5% by weight, about 7.55% by weight, about 7.62% by weight, about 7.75% by weight, about 7.80% by weight, about 7.83% by weight, about 7.85% by weight, about 7.86% by weight, about 7.875% by weight, about 7.885% by weight, about 7.88% by weight, about 7.89% by weight, about 7.90% by weight, about 7.91% by weight, about 7.92% by weight, about 7.95% by weight. about 8.0% by weight, about 8.5% by weight, about 9.0% by weight, about 9.5% by weight, about 5.0% by weight to about 6.0% by weight, about 6.0% by weight to about 7.0% by weight, about 7.0% by weight to about 8.0% by weight, about 7.25% by weight to about 8.5% by weight, about 8.0% by weight to about 9.0% by weight, about 9.0% by weight to about 10.0% by weight, about 10.0% by weight, or any amount of a methacrylate monomer, such as MIRAMER 1197 bounded by this range.

[0051] In some embodiments, the holographic photopolymer can comprise about 0.1 g of a bisphenol A diacrylate, such as SR349, about 0.2 g, about 0.25 g, about 0.3 g, about 0.325 g, about 0.35 g, about 0.375 g, about 0.4 g, about 0.425 g, about 0.45 g, about 0.5 g, about 0.55 g, about 0.6 g, about 0.7 g, about 0.8 g, about 0.9 g, about 1.0 g, about 1.1 g, about 1.2 g, about 1.3 g, about 1.4 g, about 0.1 g to about 0.2 g, about 0.2 g to about 0.3 g, about 0.3 g to about 0.4 g, about 0.4 g to about 0.5 g, about 0.5 g to about 0.6 g, about 0.6 g to about 0.7 g, about 0.7 g to about 0.8 g, about 0.8 g to about 0.9 g, about 0.9 g to about 1.0 g, about 1.0 g to about 1.1 g, about 1.1 g to about 1.2 g, about 1.2 g to about 1.3 g, about 1.3 g to about 1.4 g, about 1.4 g to about 1.5 g, about 1.5 g,PCT Application 134075-0005WO01 or any amount of a bisphenol A diacrylate, such as SR349 bounded by this range. In some embodiments, the holographic photopolymer can comprise about 5% by weight of a bisphenol A diacrylate, such as SR349, about 6.0% by weight, about 6.1% by weight, about 6.20% by weight, about 6.25% by weight, about 6.275% by weight, about 6.3% by weight, about 6.5% by weight, about 6.6% by weight, about 6.61% by weight, about 6.62% by weight, about 6.65% by weight, about 6.75% by weight, about 7% by weight, about 7.05% by weight, about 7.10% by weight, about 7.15% by weight, about 7.2% by weight, about 7.25% by weight, about 7.28% by weight, about 7.3% by weight, about 7.31% by weight, about 7.32% by weight, about 7.33% by weight, about 7.35% by weight, about 7.4% by weight, about 7.5% by weight, about 7.55% by weight, about 7.62% by weight, about 7.75% by weight, about 7.80% by weight, about 7.83% by weight, about 7.85% by weight, about 7.86% by weight, about 7.875% by weight, about 7.885% by weight, about 7.88% by weight, about 7.89% by weight, about 7.90% by weight, about 7.91% by weight, about 7.92% by weight, about 7.95% by weight. about 8.0% by weight, about 8.5% by weight, about 9.0% by weight, about 9.5% by weight, about 5.0% by weight to about 6.0% by weight, about 6.0% by weight to about 7.0% by weight, about 7.0% by weight to about 8.0% by weight, about 7.25% by weight to about 8.5% by weight, about 8.0% by weight to about 9.0% by weight, about 9.0% by weight to about 10.0% by weight, about 10.0% by weight, or any amount of a bisphenol A diacrylate, such as SR349 bounded by this range.

[0052] In some embodiments, the writing monomer can have a refractive index greater than about 1.5, about 1.5, about 1.51, about 1.52, about 1.53, about 1.54, about 1.55, about 1.56, about 1.57, about 1.58, about 1.59, about 1.6, or any refractive index bounded by this range, e.g., 1.523.

[0053] In some embodiments, the holographic photopolymer may comprise a dye system. In some embodiments, the dye system may comprise a dye and a co-initiator. In some embodiments, the dye may comprise safranine O. In some embodiments, the holographic photopolymer can comprise about 0.0001 g of a dye, such as safranine O, about 0.0002 g, about 0.00025 g, about 0.0003 g, about 0.000325 g, about 0.00035 g, about 0.000375 g, about 0.0004 g, about 0.000425 g, about 0.00045 g, about 0.0005 g,PCT Application 134075-0005WO01 0.00055 g, about 0.0006 g, about 0.0007 g, about 0.0008 g, about 0.0009 g, 0.001 g, about 0.0015 g, about 0.002 g, about 0.0025 g, about 0.003 g, about 0.0035 g, about 0.004 g, about 0.005 g, about 0.006 g, about 0.007 g, about 0.008 g, about 0.009 g, about 0.01 g, about 0.011 g, about 0.012 g, about 0.013 g, about 0.014 g, about 0.015 g, about 0.016 g, about 0.017 g, about 0.018 g, about 0.019 g, about 0.0001 g to about 0.0002 g, about 0.0002 g to about 0.0003 g, about 0.0003 g to about 0.0004 g, about 0.0004 g to about 0.0005 g, about 0.0005 g to about 0.0006 g, about 0.0006 g to about 0.0007 g, about 0.0007 g to about 0.0008 g, about 0.0008 g to about 0.0009 g, about 0.0009 g to about 0.001 g, about 0.001 g to about 0.002 g, about 0.002 g to about 0.003 g, about 0.003 g to about 0.004 g, about 0.004 g to about 0.005 g, about 0.005 g to about 0.006 g, about 0.006 g to about 0.008 g, 0.008 g to about 0.01 g, 0.01 g to about 0.012 g, 0.012 g to about 0.014 g, 0.014 g to about 0.018 g, about 0.018 g to about 0.02 g, about 0.01 g to about 0.02 g, about 0.02 g, or any amount of a dye, such as safranine O bounded by this range. In some embodiments, the holographic photopolymer can comprise about 0.10% by weight of a dye, such as safranine O, about 0.12% by weight, about 0.14% by weight, about 0.15% by weight, about 0.16% by weight, about 0.17% by weight, about 0.18% by weight, about 0.19% by weight, about 0.20% by weight, about 0.21% by weight, about 0.22% by weight, about 0.23% by weight, about 0.24% by weight, about 0.25% by weight, about 0.26% by weight, about 0.27% by weight, about 0.28% by weight, about 0.29% by weight, about 0.10% by weight to about 0.12% by weight, about 0.12% by weight to about 0.14% by weight, about 0.14% by weight to about 0.16% by weight, about 0.16% by weight to about 0.18% by weight, about 0.18% by weight to about 0.20% by weight, about 0.20% by weight to about 0.22% by weight, about 0.22% by weight to about 0.24% by weight, about 0.24% by weight to about 0.26% by weight, about 0.26% by weight to about 0.28% by weight, about 0.28% by weight to about 0.30% by weight, about 0.30% by weight, or any amount of a dye, such as safranine O bounded by this range.

[0054] In some embodiments, the co-initiator may comprise a borate salt tetrabutylammonium tris(3-chloro-4-methylphenyl) (hexyl)borate (CAS No.: 1147315). In some embodiments, the holographic photopolymer can comprise about 0.001 g of tetrabutylammonium tris(3-chloro-4-methylphenyl) (hexyl)borate, about 0.002 g, aboutPCT Application 134075-0005WO01 0.0025 g, about 0.003 g, about 0.00325 g, about 0.0035 g, about 0.00375 g, about 0.004 g, about 0.00425 g, about 0.0045 g, about 0.005 g, about 0.0055 g, about 0.006 g, about 0.007 g, about 0.008 g, about 0.009 g, about 0.01 g, about 0.015 g, about 0.02 g, about 0.025 g, about 0.03 g, about 0.0035 g, about 0.04 g, about 0.05 g, about 0.06 g, about 0.07 g, about 0.08 g, about 0.09 g, about 0.1 g, about 0.11 g, about 0.12 g, about 0.13 g, about 0.14 g, about 0.15 g, about 0.16 g, about 0.17 g, about 0.18 g, about 0.19 g, about 0.001 g to about 0.003 g, about 0.003 g to about 0.004 g, about 0.004 g to about 0.005 g, about 0.005 g to about 0.007 g, about 0.007 g to about 0.008 g, about 0.008 g to about 0.01 g, about 0.01 g to about 0.04 g, about 0.04 g to about 0.07 g, about 0.07 g to about 0.1 g, about 0.1 g to about 0.13 g, about 0.13 g to about 0.16 g, about 0.16 g to about 0.2 g, about 0.2 g, or any amount of tetrabutylammonium tris(3-chloro-4-methylphenyl) (hexyl)borate bounded by this range. In some embodiments, the holographic photopolymer can comprise about 1.0% by weight of tetrabutylammonium tris(3-chloro- 4-methylphenyl) (hexyl)borate, about 1.1% by weight, about 1.2% by weight, about 1.3% by weight, about 1.4% by weight, about 1.5% by weight, about 1.6% by weight, about 1.7% by weight, about 1.8% by weight, about 1.9% by weight, about 2.0% by weight, about 2.1% by weight, about 2.2% by weight, about 2.3% by weight, about 2.4% by weight, about 2.5% by weight, about 2.6% by weight, about 2.7% by weight, about 2.8% by weight, about 2.9% by weight, about 1.0% by weight to about 1.2% by weight, about 1.2% by weight to about 1.4% by weight, about 1.4% by weight to about 1.6% by weight, about 1.6% by weight to about 1.8% by weight, about 1.8% by weight to about 2.0% by weight, about 2.0% by weight to about 2.2% by weight, about 2.2% by weight to about 2.4% by weight, about 2.4% by weight to about 2.6% by weight, about 2.6% by weight to about 2.8% by weight, about 2.8% by weight to about 3.0% by weight, about 3.0% by weight, or any amount of tetrabutylammonium tris(3-chloro-4-methylphenyl) (hexyl)borate bounded by this range.

[0055] Some non-limiting examples of a dye that can be used in the present holographic photopolymer include safranine O (Sigma-Aldrich, Japan). Some non-limiting examples of a co-initiator that can be used in the present holographic photopolymer include borate salt tetrabutylammonium tris(3-chloro-4-methylphenyl) (hexyl)boratePCT Application 134075-0005WO01 (CAS: 1147315-11-4, Angene International Limited or Chang Zhou Qi Di Chemical Co., LTD) . In some embodiments, the ratio of the dye to the co-initiator is between about 1:10 to about 1:14.

[0056] In some embodiments, the holographic photopolymer may further comprise a reactive diluent. In some embodiments, the writing monomer may further comprise a reactive diluent. In some embodiments, the reactive diluent may comprise a solvent. In some embodiments, the solvent may comprise 1-ethyl-2-pyrrolidone (CAS No.: 2687-91- 4). In some embodiments, the holographic photopolymer can comprise about 0.1 g of 1- ethyl-2-pyrrolidone, about 0.2 g, about 0.25 g, about 0.3 g, about 0.325 g, about 0.35 g, about 0.375 g, about 0.4 g, about 0.425 g, about 0.45 g, about 0.455 g, about 0.46 g, about 0.47 g, about 0.48 g, about 0.49 g, about 0.5 g, about 0.55 g, 0.6 g, about 0.7 g, about 0.8 g, about 0.9 g, about 1.0 g, about 1.1 g, about 1.2 g, about 1.3 g, about 1.4 g, about 0.1 g to about 0.2 g, about 0.2 g to about 0.3 g, about 0.3 g to about 0.4 g, about 0.4 g to about 0.5 g, about 0.5 g to about 0.6 g, about 0.6 g to about 0.7 g, about 0.7 g to about 0.8 g, about 0.8 g to about 0.9 g, about 0.9 g to about 1.0 g, about 1.0 g to about 1.1 g, about 1.1 g to about 1.2 g, about 1.2 g to about 1.3 g, about 1.3 g to about 1.4 g, about 1.4 g to about 1.5 g, about 1.5 g, or any amount of 1-ethyl-2-pyrrolidone bounded by this range. In some embodiments, the holographic photopolymer can comprise about 5.0% by weight of 1-ethyl-2-pyrrolidone, about 6.0% by weight, about 7.0% by weight, about 7.5% by weight, about 8.0% by weight, about 8.1% by weight, about 8.2% by weight, about 8.3% by weight, about 8.4% by weight, about 8.5% by weight, about 8.75% by weight, about 9.0% by weight, about 9.25% by weight, about 9.4% by weight, about 9.5% by weight, about 9.6% by weight, about 9.7% by weight, about 9.8% by weight, about 9.9% by weight, about 10.0% by weight, about 11.0% by weight, about 12.5% by weight, about 5.0% by weight to about 6.0% by weight, about 6.0% by weight to about 7.0% by weight, about 7.0% by weight to about 8.0% by weight, about 8.0% by weight to about 9.0% by weight, about 9.0% by weight to about 10.0% by weight, about 10.0% by weight to about 11.0% by weight, about 11.0% by weight to about 12.5% by weight, about 12.5% by weight to about 15.0% by weight, about 15% by weight, or any amount of 1- ethyl-2-pyrrolidone bounded by this range.PCT Application 134075-0005WO01

[0057] The solvent is not particularly limiting, and one skilled in the art could determine an optimal choice of a solvent to use that falls in the scope of the present disclosure. Some non-limiting examples of a solvent that can be used in the present holographic photopolymer include 1-vinyl-2-pyrrolidone (CAS No: 88-12-0, BASF).

[0058] In some embodiments, the holographic photopolymer has a reflection efficiency greater than about 75%, about 80%, about 85%, or any reflection efficiency bounded by these values, e.g., 81%. FIG.3 is a graph depicting the reflection efficiency of the holographic photopolymer.

[0059] In some embodiments, the holographic photopolymer has a thickness of about 3 µm to about 12 µm, about 3 µm, about 4 µm, about 5 µm, about 6 µm, about 7 µm, about 8 µm, about 9 µm, about 10 µm, about 11 µm, about 12 µm, or any thickness bounded by this range.

[0060] In some embodiments, a holographic photopolymer may comprise a tin catalyst. In some embodiments, the tin catalyst may comprise an organotin catalyst and the solvent. The tin catalyst is not particularly limiting, and one skilled in the art could determine an optimal choice of a tin catalyst to use that falls in the scope of the present disclosure. Some non-limiting examples of a tin catalyst that can be used in the present holographic photopolymer include FOMREZ UL-28 (Galata Chemicals, United States). In some embodiments, the tin catalyst solution may comprise a 10% dimethyltin dineodecanoate and 90% 1-ethyl-2-pyrrolidone. In some embodiments, the ratio of organotin catalyst to the solvent may be about 0:10, about 1:10, about 2:10, about 3:10, about 0:9, about 1:9, about 2:9, about 3:9, about 0:8, about 1:8, about 2:8, about 3:8, or any ratio bound by this range, e.g., 1.1:9.2. It is believed that using a tin catalyst improves urethane polymerization.

[0061] In some embodiments, the holographic photopolymer may comprise about 5% by weight to about 40% by weight of the liquid additive, about 5% by weight to about 70% by weight of the polycyclic writing monomer, and about 15% by weight to about 80% by weight of the polyurethane matrix.

[0062] In some embodiments, the holographic photopolymer may have a refractive index modulation (Δn) greater than about 0.03. about 0.03, about 0.031, about 0.032,PCT Application 134075-0005WO01 about 0.033, about 0.034, about 0.035, about 0.036, about 0.037, about 0.038, about 0.039, about 0.04, or any refractive index modulation bounded by this range, e.g., 0.0387. In some embodiments, the holographic photopolymer may have a haze less than about 1%, about 1%, about 0.75%, about 0.5%, about 0.25%, or any haze bounded by this range, e.g., 0.41%.

[0063] In some embodiments, the holographic photopolymer may have a transmittance greater than about 90%. In some embodiments, the holographic photopolymer may have a transmittance greater than about 90% at 457nm, greater than 91% at 457nm, greater than 92% at 457nm, greater than 93% at 457nm, greater than 94% at 457nm, greater than 95% at 457nm, greater than 96% at 457nm, or greater than 97% at 457nm. In some embodiments, the holographic photopolymer may have a transmittance greater than about 90% at 532nm, greater than 91% at 532nm, greater than 92% at 532nm, greater than 93% at 532nm, greater than 94% at 532nm, greater than 95% at 532nm, greater than 96% at 532nm, greater than 97% at 532nm, greater than 98% at 532nm, or greater than 99% at 532nm. In some embodiments, the holographic photopolymer may have a transmittance greater than about 90% at 600nm, greater than 91% at 600nm, greater than 92% at 600nm, greater than 93% at 600nm, greater than 94% at 600nm, greater than 95% at 600nm, greater than 96% at 600nm, greater than 97% at 600nm, greater than 98% at 600nm, or greater than 99% at 600nm.

[0064] The present disclosure can be related to a holographic photopolymer and a method for making the same.

[0065] In some embodiments, a method for making the holographic photopolymer is described. In some embodiments, a method for making the holographic photopolymer may comprise: providing a polyurethane matrix comprising comprise a mesh size and a storage modulus; providing a writing monomer; providing a dye system; providing a solvent; providing a tin catalyst; mixing the polyurethane matrix and a tin catalyst to form a first mixture; mixing the dye system and a solvent to form a second mixture; and mixing the first mixture and the second mixture to form the holographic photopolymer. In some embodiments, the method may further comprise applying a vacuum to the holographic photopolymer for less than about 1 hour. In some embodiments, the vacuum can bePCT Application 134075-0005WO01 applied to the mixture for about 30 minutes. In some embodiments, the vacuum can be applied to the mixture for about 15 minutes. In some embodiments, the vacuum can be applied at a pressure of about -0.09 MPa to about 0.09 MPa. In some embodiments, the vacuum is applied to remove imperfections and / or air bubbles in the mixture and is performed prior to polymerization. In some embodiments, the method may further comprise polymerizing the mixture to form a photopolymer film. In some embodiments, the method may further comprise exposing the photopolymer film to a laser and bleaching the photopolymer film.

[0066] In some embodiments, the step for mixing the dye system, writing monomer, and polyurethane matrix to form a first mixture may further comprise mixing the dye system, writing monomer, and polyurethane matrix at a temperature of about 50 °C to about 70 °C for about 1 to about 4 hours. In some embodiments, the step for mixing the first mixture and the second mixture may further comprise cooling the first mixture to about 30 °C to about 40 °C.

[0067] In some embodiments, the method for making the holographic photopolymer may further comprise performing a two-stage chemistry approach. In some embodiments, the step of performing the two-stage chemistry approach may comprise a first stage and a second stage. In some embodiments, the first stage may comprise the step of polymerizing the holographic photopolymer to form a photopolymer film. In some embodiments, the photopolymer film may comprise a polymerized polyurethane matrix and a nonpolymerized writing monomer dispersed within the polymerized polyurethane matrix. In some embodiments, the step of polymerizing the holographic photopolymer to form a photopolymer film may further comprise curing the third mixture at room temperature for about 6 hours to about 12 hours.

[0068] In some embodiments, the second stage may comprise the step of exposing the photopolymer film to a laser having a wavelength of about 532 nm at a power density of about 1 mW / cm2to about 20 mW / cm2for about 1 second to about 30 seconds. In some embodiments, the step of exposing the photopolymer film to a laser may further comprise polymerizing the writing monomer dispersed within the polymerized polyurethane matrix. In some embodiments, the second stage may further comprise the step of bleaching thePCT Application 134075-0005WO01 photopolymer film. In some embodiments, the step of bleaching the photopolymer film may comprise exposing the holographic photopolymer to an ultraviolet light having a wavelength of about 340 nm to about 400 nm.

[0069] Utilizing a two-stage chemistry improves upon the holographic photopolymer because the two-stage chemistry process provides the ability to achieve precise control over the sequence, timing, and selectivity of different chemical transformations, enabling the synthesis of complex molecules or materials with high efficiency and accuracy. In some embodiments, a solid host matrix comprising the polyurethane matrix and additives can be formed to produce a first holographic photopolymer, and then followed by recording into a second holographic photopolymer comprising the dye system and the writing monomer.

[0070] In some embodiments, a film made according to the methods described above. In some embodiments, the film can be made in an atmosphere comprising about 25% oxygen to about 0% oxygen, less than about 25% oxygen, less than about 20% oxygen, less than about 15% oxygen, less than about 10% oxygen, less than about 5% oxygen, less than about 1% oxygen, or any percent of oxygen bounded by this range.

[0071] In some embodiments, the holographic photopolymer may be a film or coating applied to a glass substrate. In some embodiments, the holographic photopolymer may be a film or coating applied to a plastic substrate. In some embodiments, the coating may be applied to a glass substrate via a vacuum lamination coating method. In some embodiments, the coating may be applied to a plastic substrate via a roll-to-roll coating method.

[0072] In some embodiments, an augmented reality / virtual reality (AR / VR) apparatus is described. In some embodiments, the AR / VR apparatus may comprise the holographic photopolymer described above. In some embodiments, the AR / VR apparatus may comprise an AR / VR headset. In some embodiments, the AR / VR apparatus may comprise a holographic display.

[0073] Hereinafter, embodiments and methods will be described in more detail.PCT Application 134075-0005WO01 EMBODIMENTS Embodiment 1 A holographic photopolymer comprising: a polyurethane matrix comprising a mesh size and a storage modulus, wherein the storage modulus of the polyurethane matrix increases from about 10² Pa to about 5x10⁵ Pa as the mesh size decreases. Embodiment 2 The holographic photopolymer of embodiment 1 further comprising a polycyclic writing monomer and a dye system. Embodiment 3 The holographic photopolymer of embodiment 1 further comprising a solvent. Embodiment 4 The holographic photopolymer of embodiment 3, wherein the solvent comprises 1-ethyl-2-pyrrolidone. Embodiment 5 The holographic photopolymer of embodiment 1, wherein the polyurethane matrix comprises a first polypropylene glycol diol, aliphatic polyisocyanate; and wherein the mesh size is about 1 nm to about 5 nm. Embodiment 6 The holographic photopolymer of embodiment 1, wherein the polyurethane matrix comprises a first polypropylene glycol diol, polypropylene glycol triol, dicyclohexylmethane diisocyanate; and wherein the mesh size is about 5 nm to about 10 nm. Embodiment 7 The holographic photopolymer of embodiment 1, wherein the polyurethane matrix comprises a first polypropylene glycol diol, a second polypropylene glycol diol, polypropylene glycol triol, dicyclohexylmethane diisocyanate; and wherein the mesh size is about 10 nm to about 40 nm. Embodiment 8 The holographic photopolymer of embodiment 1, wherein the polyurethane matrix further comprises a tin catalyst solution. Embodiment 9 The holographic photopolymer of embodiment 8, wherein the tin catalyst solution comprises a 10% dimethyltin dineodecanoate and 90% 1-ethyl-2- pyrrolidone. Embodiment 10 The holographic photopolymer of embodiment 1, wherein the polyurethane matrix further comprises a liquid additive.PCT Application 134075-0005WO01 Embodiment 11 The holographic photopolymer of embodiment 10, wherein the liquid additive comprises ethylene glycol, propylene glycol units, ester units, or a combination thereof. Embodiment 12 The holographic photopolymer of embodiment 10, wherein the liquid additive comprises wherein n is 1 to 4, wherein R1and / or R21 to 20 carbon atoms. Embodiment 13 The holographic photopolymer of embodiment 2, wherein the polycyclic writing monomer comprises a difunctional writing monomer or a monofunctional writing monomer. Embodiment 14 The holographic photopolymer of embodiment 2, wherein the polycyclic writing monomer comprises ethoxylated bisphenol a diacrylate, ethoxylated fluorene diacrylate, m-phenoxybenzyl acrylate, biphenylmethyl acrylate, or a combination thereof. Embodiment 15 The holographic photopolymer of embodiment 2, wherein the dye system comprises a dye and a co-initiator.PCT Application 134075-0005WO01 Embodiment 16 The holographic photopolymer of embodiment 15, wherein the dye comprises safranine O, methylene blue, astrazon orange G, and / or ethyl violet, and wherein the co-initiator comprises borate salt tetrabutylammonium tris(3-chloro-4- methylphenyl) (hexyl)borate. Embodiment 17 The holographic photopolymer of embodiment 15, wherein the ratio of dye and the co-initiator is about 1:10 to about 1:14. Embodiment 18 The holographic photopolymer of embodiment 1, wherein the weight percent of the polyurethane matrix to the polycyclic writing monomer is 10-90%. Embodiment 19 An augmented reality / virtual reality apparatus comprising the holographic photopolymer as in embodiments 1-18. Embodiment 20 A film comprising the holographic photopolymer as in embodiments 1-18.PCT Application 134075-0005WO01 EXAMPLES

[0074] It has been discovered that embodiments of the holographic photopolymer as described herein have improved performance as compared to other processes. These benefits are further demonstrated by the following examples, which are intended to be illustrative of the disclosure only but are not intended to limit the scope or underlying principles in any way. Procedures to prepare photopolymer formulations

[0075] Figure 1 describes the film processing procedure. Below is a further description of how the pixel film as described herein is processed. Function Composition GramsPCT Application 134075-0005WO01 Borate salt 0.13 tetrabut lammoniumPreparation of writing monomers mixture.

[0076] 1.75 g of EA-F5710 (mixture of ethoxylated fluorene diacrylate and m- phenoxybenzyl acrylate) (OSAKA GAS Chemicals, Japan), 0.375 g of Sartomer SR349, and 0.375 g of MIRAMER M1192H (biphenylmethyl acrylate, MIWON) were mixed in dark for 3 hours at 60 °C. Preparation of photoinitiation mixture solution

[0077] 130 mg of Borate salt tetrabutylammonium tris(3-chloro-4-methylphenyl) (hexyl)borate (CAS No.: 1147315, coinitiator) and 13.0 mg of Safranine O (Photosensitizer or dye) were dissolved and mixed in 0.455 g of 1-Ethyl-2-Pyrrolidone (CAS No.: 2687-91-4) at 55 °C for 2 hours in dark. Preparation of tin catalyst solution (for urethane polymerization)

[0078] 1 part of an organotin catalyst (FOMREZ UL-28, Dimethyltin dineodecanoate) was mixed with 9 parts of 1-Ethyl-2-Pyrrolidone (CAS No.: 2687-91-4) at room temperature to form a 10% catalyst stock solution.PCT Application 134075-0005WO01 Example 1Preparation of photopolymer formulation of Example 1

[0079] The writing monomers mixture prepared from the above step, 0.4 g of GP- 3000R (Polypropylene glycol triol, SANNIX), 1.0 g of PA-2000 (Polypropylene glycol diol, SANNIX) and 0.46 g of the photoinitiation mixture solution were mixed in dark at 60 °C overnight. The mixture was cooled down to 35 °C. This was followed by the addition of 0.38 g of isocyanate (Desmodur WP 260, Covestro). The mixture was mixed vigorously for 3 minutes at 35 °C. Then 0.05 g of the tin catalyst solution was added into the resulting mixture, mixed for 3 minutes at 35 °C. The resulting liquid solution was ready to place under a vacuum at 35 °C for 15 minutes to remove air bubbles caused by mixing. Example 2PCT Application 134075-0005WO01 Preparation of photopolymer formulation of Example 2

[0080] The writing monomers mixture prepared from the above step, 0.4 g of GP- 3000R (Polypropylene glycol triol, SANNIX), 0.8 g of PA-2000 (Polypropylene glycol diol, SANNIX), 0.2 g of Arcol PPG-725 (Polypropylene glycol diol, Covestro) and 0.46 g of photoinitiation mixture solution were mixed in dark at 60 °C overnight. The mixture was cooled down to 35 °C. This was followed by the addition of 0.34 g of isocyanate (Desmodur WP 260, Covestro). The mixture was mixed vigorously for 3 minutes at 35 °C. Then 0.05 g of Tin catalyst solution was added into the resulting mixture, mixed for 3 minutes at 35 °C. The resulting liquid solution was ready to place under a vacuum at 35 °C for 15 minutes to remove air bubbles caused by mixing. Example 3Preparation of photopolymer formulation of Example 3

[0081] The writing monomers mixture prepared from the above step, 1.42 g of PA- 2000 (Polypropylene glycol diol, SANNIX) and 0.46 g of photoinitiation mixture solution were mixed in dark at 60 °C overnight. The mixture was cooled down to 35 °C. This was followed by the addition of 0.33 g of HDI trimer (Desmodur N3600, Covestro). The mixture was mixed vigorously for 3 minutes at 35 °C. Then 0.0 g of Tin catalyst solution was added into the resulting mixture, mixed for 3 minutes at 35 °C. The resulting liquid solution was ready to place under a vacuum at 35 °C for 15 minutes to remove air bubbles caused by mixing.PCT Application 134075-0005WO01 Example 4Preparation of photopolymer formulation of Example 4

[0082] The writing monomers mixture prepared from the above step, 0.8 g of a polypropylene glycol diol, such as SANNIX PA-2000 (Polypropylene glycol diol, SANNIX), 0.38 g of Efka PL 5651 (Bis(butylcarbitol)formal), CAS 143-29-3) and 0.62 g of photoinitiation mixture solution were mixed in dark at 60 ºC for at least 1 hour. The mixture was cooled down to 35 ºC. This was followed by the addition of 5 drops of BYK-310 surface levelling additive. The mixture was stirred at 35 ºC for 10 minutes, and then 0.57 g of Desmodur ultra E30600 (Aliphatic prepolymer containing ether groups and based on hexamethylene-1,6-diisocyanate (HDI)), Covestro) was added. The mixture was mixed vigorously for 3 minutes at 35 ºC.4.5 g HPLC grade acetone was added into the resultant mixture, and let it stir at 35 ºC for 3 minutes. Then 0.05 g of Tin catalyst solution was added into the resulting mixture, mixed for 3 minutes at 35 ºC. The resulting liquid solution was ready to bar coated on a flexible plastic thin film. Example 5PCT Application 134075-0005WO01 Preparation of photopolymer formulation of Example 5

[0083] The writing monomers mixture prepared from the above step, 1.167 g of a polypropylene glycol diol, such as SANNIX PA-2000 (Polypropylene glycol diol, SANNIX), 0.50 g of Efka PL 5651 (Bis(butylcarbitol)formal), CAS 143-29-3) and 0.62 g of photoinitiation mixture solution were mixed in dark at 60 ºC for at least 1 hour. The mixture was cooled down to 35 ºC. This was followed by the addition of 5 drops of BYK-310 surface levelling additive. The mixture was stirred at 35 ºC for 10 minutes, and then 0.833 g of Desmodur ultra E30600 (Aliphatic prepolymer containing ether groups and based on hexamethylene-1,6-diisocyanate (HDI)), Covestro) was added. The mixture was mixed vigorously for 3 minutes at 35 ºC.4.5 g HPLC grade acetone was added into the resultant mixture, and let it stir at 35 ºC for 3 minutes. Then 0.05 g of Tin catalyst solution was added into the resulting mixture, mixed for 3 minutes at 35 ºC. The resulting liquid solution was ready to bar coated on a flexible plastic thin film. Example 6Preparation of photopolymer formulation of Example 6

[0084] The writing monomers mixture prepared from the above step, 1.586 g of SANNIX PP-4000 (Polypropylene glycol diol, SANNIX), 0.38 g of Eastman TEG-EH plasticizer (Triethylene glycol Bis (2-ethylhexanoate), CAS 94-28-0) and 0.62 g of photoinitiation mixture solution were mixed in dark at 60 ºC for at least 1 hour. The mixture was cooled down to 35 ºC. This was followed by the addition of 5 drops of BYK-310 surface levelling additive. The mixture was stirred at 35 ºC for 10 minutes, and then 0.538 g of Desmodur ultra E30600 (Aliphatic prepolymer containing ether groups and based onPCT Application 134075-0005WO01 hexamethylene-1,6-diisocyanate (HDI)), Covestro) was added. The mixture was mixed vigorously for 3 minutes at 35 ºC.4.5 g HPLC grade acetone was added into the resultant mixture, and let it stir at 35 ºC for 3 minutes. Then 0.05 g of Tin catalyst solution was added into the resulting mixture, mixed for 3 minutes at 35 ºC. The resulting liquid solution was ready to bar coated on a flexible plastic thin film. Example 7Preparation of photopolymer formulation of Example 7

[0085] The writing monomers mixture prepared from the above step, 1.025 g of SANNIX PP-4000 (Polypropylene glycol diol, SANNIX), 0.38 g of Eastman TEG-EH plasticizer (Triethylene glycol Bis (2-ethylhexanoate), CAS 94-28-0) and 0.62 g of photoinitiation mixture solution were mixed in dark at 60 ºC for at least 1 hour. The mixture was cooled down to 35 ºC. This was followed by the addition of 5 drops of BYK-310 surface levelling additive. The mixture was stirred at 35 ºC for 10 minutes, and then 0.345 g of Desmodur ultra E30600 (Aliphatic prepolymer containing ether groups and based on hexamethylene-1,6-diisocyanate (HDI)), Covestro) was added. The mixture was mixed vigorously for 3 minutes at 35 ºC.4.5 g HPLC grade acetone was added into the resultant mixture, and let it stir at 35 ºC for 3 minutes. Then 0.05 g of Tin catalyst solution was added into the resulting mixture, mixed for 3 minutes at 35 ºC. The resulting liquid solution was ready to bar coated on a flexible plastic thin film. Glass substrate coating (Sample preparation for exposure)PCT Application 134075-0005WO01

[0086] In a light controlled (safe red-light lamp) environment, the glass substrate was cleaned and dried glass substrate. A glass substrate was cut to about 2” x 2” square. The cut glass sheet was cleaned with soap (washing detergent) and water, and then dried by nitrogen gas (N2) at room temperature for about 30 seconds and then heated to about 60 °C. A drop of synthesized photopolymer material was then applied to the glass plate, and there covered with a second glass plate, which was kept at distance of a controlled thickness by applying silica microsphere beads. The glass sandwiched samples were vacuumed and laminated using NPC vacuum chamber bonding machine (https: / / www.npcgroup.net / eng / solarcell / vacuum-bonding). After lamination, the sample specimens were left at 55 °C. Hologram-mirror recording

[0087] The polymerized photopolymer film was exposed to a Denisyuk (mirror type hologram) arrangement with a laser 532 nm and exposed with a power density of 10 mW / cm2 with exposure time 2-5 seconds. After exposure, holograms were examined visually and bleaching step under UV light was applied. The hologram laminated between two glass slides was exposed under a lamp UVASPOT 1000 RF2 from Honle UV Technology, Germany. The UVASPOT is a modular, high-intensity UV unit and system that can achieve very high uniformity throughout the irradiation field. Through various lamp and filter configurations, different spectra can be produced for applications in the ranges of UVA (340 nm - 400 nm). Reflection efficiency measurement

[0088] The results of the reflection efficiency measurements are shown in FIG.3 for Example 2. The transmission of the grating area with zero angle of incidence measured on UV-VIS spectrometer. Bragg curve analysis

[0089] The resulting Bragg curve, as show in FIGs. 4-6 and 10-12, is analyzed according to the Kogelnik theory* to deduce the refractive index modulation (Δn) and thePCT Application 134075-0005WO01 effective thickness shrinkage. Source: *Kogelnik, H., "Coupled wave theory for thick hologram gratings", The Bell System Technical Journal 48(9), 2909-2947 (1969). Film Transmittance analysis

[0090] Film transmittance, as shown in FIG. 7, was measured by UV-VIS for Example 2. Rheological Measurement

[0091] Rheological measurements of polyurethanes, as shown in FIG. 8, are performed using TA ARES-G2 instrument with parallel plate geometry (25 mm diameter, 0.5 mm gap). All rheological experiments are performed in the oscillatory mode. Curing of matrix containing liquid writing monomer is monitored with oscillatory time sweep (γ = 5-10%, ω = 1Hz). A dynamic temperature ramp (T = 0-100 ºC, temperature step 5°C, γ = 0.1%, Ω = 6.28 rad / s) is ran on the cured matrix containing liquid writing monomer that is equivalent to the photopolymer system having writing monomers dispersed in the matrix binder. Haze and Total Transmission

[0092] Haze and total transmission mode results using HunterLab UltraScan VIS are shown in FIG.9.

[0093] As used herein, unless otherwise specified the use of the ordinal adjectives “first” and “second,” to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

[0094] Use of the term “may” or “may be” or “can” should be construed as shorthand for “is” or “is not” or, alternatively, “does” or “does not” or “will” or “will not,” etc. For example, the statement “a thermally conductive composite may further comprise a backing layer” should be interpreted as, for example, “In some embodiments, a thermallyPCT Application 134075-0005WO01 conductive composite further comprises a backing layer,” or “In some embodiments, a thermally conductive composite does not further comprise a backing layer.”

[0095] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties, such as, molecular weight, reaction conditions, and so forth used in the specification and embodiments are to be understood as being modified in all instances by the term “about.” The term “about” as used herein, can include any numerical value that can vary without changing the basic function of that value. When used with a range, “about” also discloses the range defined by the absolute values of the two endpoints. The term “about” may refer to plus or minus 10% of the indicated number.

[0096] Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached embodiments are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, and not as an attempt to limit the application of the doctrine of equivalents. To the scope of the embodiments, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0097] For the processes and / or methods disclosed, the functions performed in the processes and methods may be implemented in differing order, as may be indicated by context. Furthermore, the outlined steps and operations are only provided as examples, and some of the steps and operations may be optional, combined into fewer steps and operations, or expanded into additional steps and operations.

[0098] This disclosure may sometimes illustrate different components contained within, or connected with, different other components. Such depicted architectures are merely examples, and many other architectures can be implemented which achieve the same or similar functionality.

[0099] The terms used in this disclosure, and in the appended embodiments, are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including, but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes, but is not limited to,” etc.). In addition, if a specific number of elements is introduced, this may be interpreted to include at least the recited number, as may be indicated by context (e.g., the bare recitation ofPCT Application 134075-0005WO01 "two recitations," without other modifiers, includes at least two recitations, or two or more recitations). As used in this disclosure, any disjunctive word and / or phrase presenting two or more alternative terms should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”

[0100] The terms and words used are not limited to the bibliographical meanings but are merely used to enable a clear and consistent understanding of the disclosure. The terms “a,” “an,” “the” and similar referents used in the context of describing the present disclosure (especially in the context of the following embodiments) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples, or representative language (e.g., “such as”) provided herein is intended merely to better illuminate the present disclosure and does not pose a limitation on the scope of any embodiments. No language in the specification should be construed as indicating any non-embodied element essential to the practice of the present disclosure.

[0101] Groupings of alternative elements or embodiments disclosed herein are not to be construed as limitations. Each group member may be referred to and embodied individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and / or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended embodiments.

[0102] Certain embodiments are described herein, including the best mode known to the inventors for carrying out the present disclosure. Of course, variations on these described embodiments, will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the present disclosure to be practiced otherwise than specifically described herein. Accordingly, the embodiments include all modifications and equivalents of the subject matter recited in the embodimentsPCT Application 134075-0005WO01 as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is contemplated unless otherwise indicated herein or otherwise clearly contradicted by context. In closing, it is to be understood that the embodiments disclosed herein are illustrative of the principles of the embodiments. Other modifications that may be employed are within the scope of the embodiments. Thus, by way of example, but not of limitation, alternative embodiments may be utilized in accordance with the teachings herein. Accordingly, the embodiments are not limited to the embodiments precisely as shown and described.

[0103] By the term "substantially" it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other suitable factors may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0104] Aspects of the present disclosure may be embodied in other forms without departing from its spirit or essential characteristics. The described aspects are to be considered in all respects illustrative and not restrictive. The embodied subject matter is indicated by the appended embodiments rather than by the foregoing description. All changes, which come within the meaning and range of equivalency of the embodiments, are to be embraced within their scope.

Claims

PCT Application 134075-0005WO01 CLAIMS We claim:

1. A holographic photopolymer comprising: a polyurethane matrix comprising a mesh size and a storage modulus, wherein the storage modulus of the polyurethane matrix increases from about 10² Pa to about 5x10⁵ Pa as the mesh size decreases.

2. The holographic photopolymer of claim 1 further comprising a polycyclic writing monomer and a dye system.

3. The holographic photopolymer of claim 1 further comprising a solvent.

4. The holographic photopolymer of claim 3, wherein the solvent comprises 1-ethyl- 2-pyrrolidone.

5. The holographic photopolymer of claim 1, wherein the polyurethane matrix comprises a first polypropylene glycol diol, aliphatic polyisocyanate; and wherein the mesh size is about 1 nm to about 5 nm.

6. The holographic photopolymer of claim 1, wherein the polyurethane matrix comprises a first polypropylene glycol diol, polypropylene glycol triol, dicyclohexylmethane diisocyanate; and wherein the mesh size is about 5 nm to about 10 nm.

7. The holographic photopolymer of claim 1, wherein the polyurethane matrix comprises a first polypropylene glycol diol, a second polypropylene glycol diol, polypropylene glycol triol, dicyclohexylmethane diisocyanate; and wherein the mesh size is about 10 nm to about 40 nm.

8. The holographic photopolymer of claim 1, wherein the polyurethane matrix further comprises a tin catalyst solution.

9. The holographic photopolymer of claim 8, wherein the tin catalyst solution comprises a 10% dimethyltin dineodecanoate and 90% 1-ethyl-2-pyrrolidone.

10. The holographic photopolymer of claim 1, wherein the polyurethane matrix further comprises a liquid additive.

11. The holographic photopolymer of claim 10, wherein the liquid additive comprises ethylene glycol, propylene glycol units, ester units, or a combination thereof.PCT Application 134075-0005WO01 12. The holographic photopolymer of claim 10, wherein the liquid additive comprises wherein n is 1 to 4, wherein R1and / or R21 to 20 carbon atoms.

13. The holographic photopolymer of claim 2, wherein the polycyclic writing monomer comprises a difunctional writing monomer or a monofunctional writing monomer.

14. The holographic photopolymer of claim 2, wherein the polycyclic writing monomer comprises ethoxylated bisphenol a diacrylate, ethoxylated fluorene diacrylate, m-phenoxybenzyl acrylate, biphenylmethyl acrylate, or a combination thereof.

15. The holographic photopolymer of claim 2, wherein the dye system comprises a dye and a co-initiator.

16. The holographic photopolymer of claim 15, wherein the dye comprises safranine O, methylene blue, astrazon orange G, and / or ethyl violet, and wherein the co- initiator comprises borate salt tetrabutylammonium tris(3-chloro-4-methylphenyl) (hexyl)borate.PCT Application 134075-0005WO01 17. The holographic photopolymer of claim 15, wherein the ratio of dye and the co- initiator is about 1:10 to about 1:

14.

18. The holographic photopolymer of claim 1, wherein the weight percent of the polyurethane matrix to the polycyclic writing monomer is 10-90%.

19. An augmented reality / virtual reality apparatus comprising the holographic photopolymer in any of claims 1-18.

20. A film comprising the holographic photopolymer in any of claims 1-18.

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