laser-induced photopolymerization is a new rapid prototyping technique that can be used in free-form manufacturing of high aspect ratio microstructures. The process consists of UV light-induced ultrafast polymerization of multifunctional monomers. The prototype to be manufactured is built layer by layer in a stepwise manner. The system is composed of a laser, a multiaxial positioning stage with a stage-motion controller, and a computer control having interfaces with the optical and mechanical part of the system. A database describing a three-dimensional microstructure of specified dimensions and topology is generated by a computer software code (AutoCAD). The structure is then sliced into thin two-dimensional layers. This information is utilized in the computer to position the laser over a thin layer of liquid photo-sensitive monomers on top of a platform immersed in a vat of liquid monomers. The thin layer of monomers is polymerized and solidified when exposed to the laser light. Laser exposure can be free-form or through a mask. In free-form exposure, scanning of the monomer layer by a pulsed laser beam is accomplished through computer-controlled movement of the stage in the x,y plane that coincides with the shape of the thin layer generated by the software code. The solidified layer residing on the platform is lowered to allow another thin layer of liquid monomers on top of the solidified layer (another technique raises a UV window positioned on top of the solidified monomer layer to allow a new layer of monomer liquid to flow on top of the solid layer). The irradiation process is then repeated and layers are stacked until the prototype microstructure is produced.
KeywordsDark Period Monomer Conversion Direct Writing Monomer Resin Termination Rate Constant
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