Slant beam rotation UV scanning to eliminate stair-steps in stereolithography fabrications

Stair-stepping is one of the major causes of poor surface finish in stereolithography (SLA) and other rapid prototyping (RP) systems. Taking this effect as an inability of conventional scanning systems, which can only fabricate layers with straight edges, the authors have studied and implemented a new SLA scanning technique. In the new method, termed slant beam rotation (SBR) scanning, an inclined beam of ultra violet (UV) light fabricates slant edges of individual layers, while an additional degree of freedom (DOF) in the scan head is used to rotate the beam inside the resin through 360 degrees to change the build angle. The data format needed to complete this scanning process has also been prepared and reported along-with the development of the stereolithography system. Through fabrications and analyses, it has been found that average surface roughness of a typical stair-stepped object reduced to 1.1 mu m from 18.0 mu m otherwise.