Compact simple dynamic holographic devices based on pattern-aligned liquid crystal micro-structures

Holographic display has received extensive attention in recent years due to its unique display characteristics. With the discovery of the geometric phase, liquid crystal (LC) devices made by utilizing its excellent property that the phase modulation is independent of the optical path are compact and efficient, providing what we believe to be a new solution for miniaturized holographic devices. In this paper, we demonstrate dynamic holographic devices based on pattern-aligned LC micro-structures, featuring compact sizes and simple electronic driving circuits. The theoretical part of this work is based on the fast Fourier transform and uses self-written code for numerical calculations, which is the calculation and simulation of the two-dimensional light intensity distributions and propagation paths of Fresnel diffraction with arbitrary geometric phase distributions. The geometric phase distribution of the diffractive optical element corresponding to an arbitrary holographic pattern is obtained through the inverse Fourier transform calculation. By using a digital micro-mirror device (DMD), pixelated quasi-continuous modulation from 0 to 2<i>π</i> of the LC geometric phase can be achieved. Through demonstrating four-frame images generated from two pattern-aligned LC cells, a method of fabricating low-cost and compact dynamic holographic devices based on the LC geometric phase is proposed, which provides a new option for practical applications such as dynamic digital signage and traffic e-signs.