Measurement of liquid surface unevenness in stereolithography

Abstract

Unevenness of the resin liquid surface causes uneven thickness of photo-hardened layers, resulting in reduced precision in stereolithography. Conventional stereolithography machines are equipped with leveling devices to prevent unevenness of the liquid surface. There however exists no system to measure flatness of the liquid surface at present, making it difficult to ensure flatness at all times. This paper proposes a device and method to measure uneven liquid surface. Factors causing measurement errors were analyzed, actual uneven surface shapes were measured, and measuring accuracy was examined to verify feasibility to apply this method to stereolithography. The developed equipment was found to be capable of measuring unevenness up to 6 microns.