Layer thickness control for stereolithography utilizing variable liquid elevation and laser focal length

摘要

An apparatus and method for controlling the surface level of a liquid residing within a relatively vertically stationary workpiece support platform disposed within a reservoir for use in stereolithographic processes wherein a layered object or structure is formed by selectively curing portions of the liquid to at least a semisolid state in multiple, at least partially superimposed layers. Providing precise control of liquid depth over the vertically stationary platform as well as focusing of a laser beam for curing the liquid at the varying surface levels thereof relative to the vertically stationary platform is effected using a laser range finder system controlled by a computer used to control the stereolithographic process in a closed loop fashion.