Extended holographic wave front printer setup employing two spatial light modulators

Abstract

Holographic wave front printing is an emerging technique for the fabrication of computer-generated image holo- grams and holographic optical elements based on wave front synthesis via adaptive optical elements. Progress is fueled by the availability of high quality spatial light modulators and industrial grade holographic film materials. Striving for increased relevance for applications, a flexible and precise way of fabricating large-area, highly efficient holographic optical elements providing complex wave front transformations is sought after. In this pa- per, we report on a novel holographic printer setup for the recording of volume holographic optical elements (vHOEs) in a step-wise fashion by adjacently recording many sub-holograms. The setup is centered around two phase-only reflective spatial light modulators, which are used to shape the recording wave fronts. The recording wave fronts propagate through the setup on a common path and interfere in the focal plane of a reversely illuminated microscope objective, where the holographic film is located. The setup is additionally equipped with two characterization beam paths based on CMOS cameras allowing for accurate control of printing parameters and in-situ characterization of diffraction properties of the printed holograms. We demonstrate the recording of high-efficiency transmission vHOEs in development grade Bayfol HX TP* photopolymer in our setup. In order to exemplify the setup’s characterization capability, we present results of test series concerning vHOE diffraction efficiency as a function of exposure dose and the influence of photopolymer development dynamics on multiplexed exposure. Finally, we showcase a printed high-contrast holographic diffuser screen for see-through display applications.