Nametic liquid crystals (NLC) are most commonly used liquid crystal (LC) materials in various light modulators , displays  and lenses . However those materials have a fundamental limitation: they are polarization sensitive since the refractive index modulation here is achieved by the electric field induced reorientation of their local anisotropy axis. Thus, the standard imaging optical systems (used in consumer electronic products and dealing with natural light sources ) have to use double NLC structures in a cross oriented way and in rather requiring geometrical conditions.
We describe a simple but very efficient optical device that allows the dynamic focusing of unpolarized light using a single NLC layer. The operation principle of the proposed device is based on the combination of an electrically variable “single layer lens” with two fixed optical elements for light reflection and 90 polarization flip. Such an approach is made possible thanks to the close integration of thin film wave plate and mirror. Preliminary experimental studies of the obtained electrically variable mirror show very promising results.
Several standard camera geometries, using the double layer approach, and possible new geometries, using the reflective approach, will be described.
1. Gordon D. Love, Wave-front correction and production of Zernike modes with a liquid-crystal spatial light modulator, Applied Optics, Vol. 36, Issue 7, pp. 1517-1524 (1997).
2. P. Yeh and C. Gu, Optics of Liquid Crystal Displays, Wiley, 1999.
3. T. Galstian, Smart Mini-Cameras, CRC Press, Taylor and Francis group, 2013.