Size, weight, and power breakthrough in nonmechanical beam and line-of-sight steering with geo-phase optics.

Thin-film geo-phase optics have the potential to dramatically reduce size, weight, and power for large-aperture optical components as well as provide nonmechanical functionality. Topics are presented in manner of increasing conceptual and system complexity to convey the different levels and aspects of system performance improvements. An 8'' aperture, lightweight geo-phase lens is presented followed by discussions on both mechanical and nonmechanical beam steering embodiments. Laser damage thresholds for the thin-film geo-phase prisms are reported. Highly efficient and spectrally broadband nonmechanical line-of-sight steering is also demonstrated. Lastly, novel fabrication techniques, to the best of our knowledge, and the associated reduced fabrication cost implications are presented.

Light-induced gliding of the easy orientation axis of a dye-doped nematic liquid crystal.

We studied the effect of light-induced gliding of the easy axis of dye-doped nematic liquid crystal on an aligning polymer surface. The observed drift of the easy axis is over tens of degrees and is caused by light-induced anisotropic adsorption and/or desorption of dye molecules on or from the aligning layer in the presence of light-induced bulk torque. We present a theoretical model that explains the experimental data in terms of the light-induced changes of the adsorbed dye molecules angular distribution due to their exchange with the dye molecules from the liquid crystal bulk.

Evolution of light-induced anchoring in dye-doped nematics: experiment and model.

A series of experiments was carried out to describe the evolution of light-induced anchoring in dye-doped nematic liquid crystals (LCs) at irradiation with polarized light. The experiments included cells filled with a pure pentyl-cyanobiphenyl (5CB) and containing a layer of azo dye deposited on an aligning film, as well as cells filled with azo dye doped 5CB, which allowed us to distinguish the role of "surface" and "bulk" dye molecules in the evolution of light-induced anchoring. Modifications of the spectra of spontaneously adsorbed dye molecules under illumination enabled us to assert that light-induced desorption is a mechanism responsible for producing an easy orientation axis in a dark-adsorbed layer. We found that the evolution of light-induced anchoring involves a competition between light-induced desorption and adsorption of the dye molecules on the aligning surface, and the final anchoring is determined by the total light irradiation dose. These data allowed introducing a theoretical model of light-induced anchoring of dye-doped nematic LCs that quantitatively described the experimental results and portrayed the whole evolution of the dye-doped LC cell at irradiation.