Continuous grey-scale image storage using optically aligned nematic liquid crystals

LIQUID crystals have been widely used in flat-panel-display applications for many years. But attempts to use liquid crystals as optical data-storage media1 have met with limited success, owing to both the difficulties of encoding grey-scale images2 and the complexity of writing and rewriting schemes3,4. Fundamental to all liquid-crystal-based optical devices is the control of average molecular orientation over macroscopic length scales, and it has recently been shown that polarized light can be used to induce such alignment with high spatial resolution5á-12. Here we show that a similar strategy can be used to record high-resolution, erasable, continuous grey-scale images. This approach shows potential for low-cost, high-density optical data-storage applications.