Abstract: An improved stereolithographic apparatus and method is described. In one embodiment, the improvement includes immersing at least a portion of a part in a volume of a liquid solvent in a vapor degreaser while subjecting the portion to ultrasonic agitation to substantially remove excess resin. Several examples of solvents are provided, including ethanol, and Freon TMS. In a second embodiment, the improvement includes building the part on a layer of liquid resin supported by a volume of a dense, immiscible, and UV transparent intermediate liquid, and integratably immersing at least a portion of the built part in the intermediate liquid, and then either subjecting the immersed portion to ultrasonic agitation to substantially remove excess resin, or subjecting the immersed portion to UV light. Several examples of intermediate liquids are provided, including perfluorinated fluids, such as Fluorinert FC-40, and water-based salt solutions, such as solutions of magnesium sulfate or sodium chloride in water.

Abstract: Methods and apparatus for reducing surface discontinuities, resulting from the formation of a three-dimensional object out of a plurality of stacked layers, during layer by layer stereolithographic formation of the three-dimensional object. The discontinuities between layers are reduced by utilizing formation and solidification of thin fill layers near the edges of thicker structural layers or by utilizing surface tension effects to smooth discontinuities between the structural layers by formation of meniscuses of building material and solidifying the meniscuses.