Continuously tunable smectic A(*) liquid-crystal color filter

A new continuously tunable color filter, which uses smectic A(*) liquid-crystal half-wave plates, is described and experimentally demonstrated. Multiple-stage Lyot filters with broad tunability and high finesse can be constructed with this design. The transmission characteristics of a single-stage filter, which is continuously tuned over 115 nm of the visible spectrum, are presented. Experimental results are compared with computer simulations, and they show excellent agreement. The advantages of the smectic A(*) liquid-crystal tunable filter over existing filter structures include low switching voltages (+/-30 V), rapid tunability (10 MHz), potentially high transmission, wide field of view, and large aperture.