Reliable photopolymer for new applications: vHOEs recorded into Bayfol® HX film resisting the environment

Abstract

Bayfol^® HX photopolymer films prove themselves as easy-to-process recording materials for volume holographic optical elements (vHOEs) and are available in customized grade at industrial scale. Their full-color (RGB) recording and replay capabilities are two of their major advantages. Moreover, the adjustable diffraction efficiency, tunable angular and spectral selectivity of vHOEs recorded into Bayfol^® HX as well as their unmatched optical clarity enables superior invisible “off Bragg” optical functionality. As a film product, the replication of vHOEs in Bayfol^® HX can be carried out in a highly cost-efficient and purely photonic roll-to-roll (R2R) process. Utilizing thermoplastic substrates, Bayfol^® HX was demonstrated to be compatible to state-of-the-art plastic processing techniques like thermoforming, film insert molding and casting, which opened using a variety of industry-proven integration technologies for vHOEs. Therefore, Bayfol^® HX makes its way in applications in the field of augmented reality such as Head-up-Displays (HUD) and Headmounted- Displays (HMD), in free-space combiners, in plastic optical waveguides, and in transparent screens. Also, vHOEs made from Bayfol^® HX are utilized in highly sophisticated spectrometers in astronomy as well as in narrow band notch filters for eyeglasses against laser strikes. Especially in the automotive application field the required reliability performance is very high and demanding. Bayfol® HX film itself and its integration in respective parts were further optimized to show significantly increased resilience against environmental conditions. Those parts pass automotive standard tests like accelerating weathering tests (PV 3930) and thermal cycling test (PV 1200), while keeping the performance level of the vHOEs recorded into Bayfol^® HX film unchanged. This enables a long-term stability of the final product and thus enabling the material to be used in even more applications. This especially holds true for permanent or most frequently outdoor applications such as automotive lighting, HUD or HMD.