Three-dimensional objects curing

Rapid prototyping or stereolithography or three-dimensional object curing is a photochemical process used to produce solid three-dimensional objects, such as models, masters, or patterns with any shape directly from a design. 

Three-dimensional objects are generated within a fluid medium, which is selectively cured by radiation brought to a selective focus at prescribed intersection points within the three-dimensional volume of the fluid medium. 

When UV-curable resins are used as laminated adhesives to protect three-dimensional objects having complex shapes, it may happen that some remote areas wiU not be accessible to UV-radiation and therefore remain uncured. To address the issue of such shadowed areas, dual-cure systems combining UV-irradiation and thermal treatment have been developed [71]. They contain two types of reactive functions a UV-curable functional group (usually an acrylate double bond)... 

Because of their frequently complicated shapes, three-dimensional (3D) objects require different coating techniques, such as spray, dip, and flow and spin coating. The lamps in curing units for 3D objects are stationary and the parts pass in front of them. They usually rotate two to three times as they pass through the irradiation zone. The irradiation zone must have a shield to eliminate direct and first scattered light. Because of the complexity of coated parts and high demands on quality, UV lamps are frequently mounted on robotics (shown previously in Figure 7.1). 

Since two photons are required to initiate the polymerisation, curing will only take place in the focal point of the laser [i.e. where the concentration of photons is the highest]. The microscope objective used to focus the laser beam can be moved relative to the sample. After removal of the uncured material, complex three-dimensional structures can be achieved via direct laser writing [127, 149]. Interestingly, biodegradable polyester oligomers have... 

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