Charles W. Hull (born May 12, 1939) is the co-founder, executive vice president and chief technology officer of "3D Systems" (1986). He is the inventor of the solid imaging process known as stereolithography (3D printing), the first commercial rapid prototyping technology, and the STL file format.
The technology for printing physical 3D objects from digital data was first developed by Charles Hull in 1984. He named the technique as "Stereolithography" (entitled "Apparatus for Production of Three-Dimensional Objects by Stereolithography") and obtained a patent for the technique in 1986, March 11. Hull defined stereolithography as a method and apparatus for making solid objects by successively "printing" thin layers of the ultraviolet curable material one on top of the other.
A Stereolithography machine consists of an UV (ultraviolet) laser, a build platform and a vat of liquid photopolymer. It works as follows. A software first divides the 3D CAD model into several thin layers and sends the data to the machine. The UV laser draws the first layer on the surface of photopolymer solidifying it onto the build platform. The platform is then lowered and recoated with the liquid photopolymer. The UV laser traces and solidifies the next layer. The process repeats until the complete three dimensional model is built.