Abstract: A light directing optical structure is formed of a light waveguide preferably made of clear plastic; attached to or formed with the waveguide are a multiplicity of prisms. Each prism, due to its index of refraction, provides an aperature where light may escape the waveguide rather than remain confined due to total internal refraction. The light escaping the waveguide is reflected from a side face of the prism, and redirected in a desired direction. The propagation paths within the waveguide are such that the light emerging through the aperature is of only a fairly closely constrained range of angles; as a result the light that is redirected by the side face of the prism is of a similarly constrained range of angles.The geometry of the prism can be optimized to direct the output light perpendicular to the plane, or at a desired angle other than perpendicular.

Abstract: The present invention provides a method of substantially dissolving contaminants or removing contaminants from the surface of a substrate. The method comprises the step of using a solvent of the Formula ##STR1## wherein R is a hydrocarbon having 1 to 3 carbon atoms and A and B are the same or different and partially fluorinated or perfluorinated alkyl groups having 1 to 2 carbon atoms.