The main aim of the research has been to produce and evaluate a high-quality diffusion
screen to display projected film and television images. The screens have also been found
to effectively de-pixelate LCD arrays viewed at a magnification of approximately 4x.
The production process relies on the formation of localized refractive index gradients in a
photopolymer. The photopolymer, specially formulated and supplied by Du Pont, is
exposed to actinic light through a precision contact mask to initiate polymerization within
the exposed areas. As polymerization proceeds, a monomer concentration gradient exists
between the exposed and unexposed regions allowing the monomer molecules to diffuse.
Since the longer polymer chains do not diffuse as readily, the molecular concentration of
the material, which is related to its refractive index, is then no longer uniform. The
generation of this refractive index profile can, to some extent, be controlled by careful
exposure of the photopolymer through the correct mask so that the resulting diffusion
screen can be tailored to suit specific viewing requirements. [Continues.
