Non-display bio-optic applications of liquid crystals

Liquid crystal (LC) devices have been largely developed for LC displays and in the last decade for optical telecommunications; however, their application in the field of optical imaging is just starting to emerge. They can be miniaturised and thus have a great potential to be used with miniature optical imaging systems for biomedical applications. LC devices specifically designed for integration into biomedical optical imaging systems are reviewed. Using a combination of a few LC retarders, spectropolarimetric imaging of tissue can be obtained. LC tunable filters with high dynamic range and large throughput are designed for hyperspectral imaging and for spectral domain optical coherence tomography. The designs are based on several concepts, both using the classical stack of retarders and using more modern designs based on single layer in a Fabry-Perot cavity, in a resonant waveguide structure or in a photonic crystal.