STEREOLITHOGRAPHY
Stereolithography (SLA) is an additive manufacturing process that belongs to the Vat Photopolymerization family. In SLA, an object is created by selectively curing a polymer resin layer-by-layer using an ultraviolet (UV) laser beam. The materials used in SLA are photosensitive thermoset polymers that come in a liquid form.
SLA is famous for being the first 3D Printing technology: its inventor patented the technology back in 1986. If parts of very high accuracy or smooth surface finish are needed, SLA is the most cost-effective 3D printing technology available. Best results are achieved when the designer takes advantage of the benefits and limitations of the manufacturing process.
SLA has many common characteristics with Direct Light Processing (DLP), another Vat Photopolymerization 3D printing technology. For simplicity, the two technologies can be treated as equals.
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Schematic representation of Stereolithography: a light-emitting device a) (a laser or DLP) selectively illuminates the transparent bottom c) of a tank b) filled with a liquid photo-polymerizing resin. The solidified resin d) is progressively dragged up by a lifting platform e)
Source: https://en.wikipedia.org/wiki/Stereolithography