Preparation and focusing characteristics of polarized holographic photo-alignment liquid crystal cylindrical lenses

In the field of near-eye display, volume holographic gratings, as the promising coupling elements, can couple the light into and out of the waveguide. Liquid crystal polarization hologram has strong polarization selectivity and conversion performance, which can not only realize the coupling of light, but also be used as optical switch, lens, grating, diffuser, achromatic and color optical elements. In this paper, liquid crystal polarization holographic cylindrical lenses were prepared by photo-alignment liquid crystal technology combined with holographic optical path, and their imaging characteristics were studied. In the off-axis holographic interferometric optical path, with the method of the interference of plane wave and cylindrical wave, the SD1 photocontrol orientation technology was used to fabricate a variable line spacing liquid crystal polarization diffraction lens.After being exposed to a 457 nm laser holography, samples of holographic column lenses were prepared with exposure angles of 21.96 degrees, 26.42 degrees, and 33.20 degrees, respectively. These angles corresponded to liquid crystal polarizing lenses with varying spacing periods. The change of the period can be realized by changing the angle between the two interference light beams which verified by theoretical calculation.Subsequently, the diffraction characteristics and anomalous dispersion characteristics of liquid crystal polarizing lens were analyzed experimentally. The results indicate that liquid crystal polarization holographic elements have enormous potential in the field of near eye displays.