Digital light processing is a photopolymer-based 3D printing technology. It was invented in 1987 by Texas Instruments. DLP projects a UV light onto the build platform to polymerize each part layer. The layer’s cross-section must be masked so only the specified areas get polymerized. This masking is done with a DMD (Digital Micromirror Device) containing thousands of microscopic swiveling mirrors to direct light. They are arranged into a digital pattern for each layer to direct the UV light to the photopolymer or a heat sink below. Alternatively, LED screens can be used as the light source, and the masking is done by simply turning off the LEDs wherever polymerization is not required. The resolution of a DLP 3D printer depends on the resolution of the LED or DMD array as well as the distance from the light source to the polymerization zone. DLP parts comprise cubic volumes called voxels – essentially 3-dimensional pixels. This means any curved edge will look like it was built from many tiny cubes.
DLP 3D printers are cheaper and can print significantly faster than most SLA 3D printers. The image below shows a typical DLP printer:
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