Morphology of reflection holograms formed in situ using polymer-dispersed liquid crystals

The morphology of a reflection grating formed using a polymer-dispersed liquid crystalline material system is examined using low-voltage high-resolution scanning electron and transmission electron microscopy. The grating is formed by establishing a fringe pattern in the intensity profile of an argon-ion laser line (λ = 488 nm) leading to a periodic anisotropic cure through the thickness of the film. The in situ, one-step procedure produces periodic layers of polymer- and LC-rich planes lying parallel to the film surface. Droplet diameters are very small (<100 nm) and little coalescence of individual droplets is observed. The grating spacing measured from electron micrographs (153 nm) nearly corresponds to the expected spacing from the observed reflection notch at λ = 472 nm.