New photopolymer used as a holographic recording material

Fabrication of a phase transmission holographic optical element in polycarbonate and its characterization

The phase transmission holographic optical element in silver halide holographic emulsion, especially for holographic collimator sights, is fabricated and the desired diffraction efficiency is obtained with very high transmission. One of the main drawbacks of these holograms are that they become dark by being exposed under sunlight, and this darkness drastically reduces the visible transmission and diffraction efficiency of a holographic optical element, hence it is not suitable for weapon sight application. To overcome this problem, we transferred a holographic optical element with a reticle image from silver halide into polycarbonate by using copying, electroforming, and recombination techniques. The holographic optical element in polycarbonate has many advantages; the detailed method of fabrication, transfer, and its characterization are presented. The very interesting result of diffraction efficiency variation with angle obtained in polycarbonate is discussed.

Comparison of holographic photopolymer materials by use of analytic nonlocal diffusion models

The one-dimensional diffusion equation governing holographic grating formation in photopolymers, which includes both nonlocal material response and generalized dependence of the rate of polymerization on the illuminating intensity, has been previously solved under the two-harmonic expansion assumption. The resulting analytic expressions for the monomer and polymer concentrations have been derived and their ranges of validity tested in comparison with the more accurate numerical four-harmonic case. We used these analytic expressions to carry out a study of experimental results presented in the literature over a 30-year period. Automatic fitting of the data with these formulas allows material parameters, including the nonlocal chain-length variance sigma, to be estimated. In this way, (i) a quantitative comparison of different materials can be made, and (ii) a standard form of experimental result presentation is proposed to facilitate such a procedure.

Holographic optical elements recorded on spherical surfaces with photopolymers

A method for recording of holograms on spherical substrates is presented. As recording material we used a photopolymer placed between two spherical glass plates that are concentric.