Stereolithography (SLA) creates 3D printed objects from a liquid (photopolymer) resin by using a light source to solidify the liquid material.
To create a 3D printed object, a build platform is submerged into a translucent tank filled with liquid resin. Once the build platform is submerged, a light located inside the machine maps each layer of the object through the bottom of the tank, thus solidifying the material.
After the layer has been mapped and solidified by the light source, the platform lifts up and lets a new layer of resin flow beneath the object once again. This process is repeated layer by layer until the desired object has been completed. There are two common methods today differentiated by the light source: SLA uses a laser, whereas DLP employs a projector.