An electrically tunable focusing and filtering infrared liquid-crystal device for light-field imaging and spectral imaging

In this paper, we propose a novel dual-function infrared liquid-crystal device (DF-ILCD), which can simultaneously perform both tunable focusing and filtering functions through applying alternating current (AC) voltage signals. The key functional micro-structure of the DF-ILCD includes: two paralleled 1-mm-thick ZnSe substrates with 20-nm-thick aluminum (Al) films over their inner surfaces and a periodic repetition microholes over both substrates. The Al films act as both high-reflection films and conductive films. The conventional UV-photolithography and wet-etching process are used to fabricate an arrayed micro-hole with a diameter of 120 mu m and a period of 336 mu m over each substrate. The micro-cavity formed between ZnSe substrates has a typical depth of similar to 12 mu m, which is fully filled by a nematic liquid-crystal (LC) materials. Experiments demonstrate that the proposed device exhibit both filtering function based on Fabry-Perot (FP) effect and electrically controlled tunable focusing function generated by the micro-hole electrodes, which is very promising for realizing both the light-field imaging and spectral imaging in the infrared wavelength range.