DLP (Direct Light Processing) . It is the process of using light to cure photopolymer resin into solid 3D objects one layer at a time. The printer uses a special wavelength of light to activate the chemical reaction of the resin. Most DLP prints are almost seamless.
DLP printers have a vat full of resin which is suspended above a projector. The light from the projector shines up through the base of the vat at the resin. The projector only lights up the areas of the vat that are needed for the current layer/slice of the 3D model. A layer of specially coated glass is lowered into the vat and the freshly cured resin sticks to the glass. The glass is then raised up out of the liquid and then the projector fires again. The fresh resin sticks to the previous layer and begin to form a part. The process is repeated over and over again until the part is done.
Main advantage of this process is that the laser can cure a full layer of the print at once. This makes the printer relatively fast in comparison with SLA printers
Cons: Material and Tooling costs, postprocessing time.