Holographic Lenses for See-Through Applications Recorded Without Prisms.

Holography offers a wide range of solutions for see-through display applications, where holographic optical elements can act either as mirrors or as waveguide couplers. In the latter case, one of the main challenges lies in achieving efficient mass fabrication. To address this limitation, the use of wavelength shift recording has been proposed, as it eliminates the need for prisms and index matching during the recording process. These elements are typically designed as slanted holographic gratings, recorded using either transmission or reflection geometries. Photopolymers as holographic recording materials are a promising solution for such applications because of their attractive optical properties. However, their inherent volume changes affect the optical performance of the recorded elements. In this paper, we propose the use of holographic lenses as wave couplers, which enables control over additional parameters such as magnification and optical aberrations. We analyze the limitations of this recording approach when prisms are not employed, and we investigate the influence of photopolymer shrinkage on hologram quality, comparing lenses recorded using transmission and reflection holography with different focal lengths.