US Patent 10589513 Three dimensional printing system with improved optical path

A three dimensional printing system includes a support plate, a resin vessel, and one or more mechanical features. The support plate includes a ridge surrounding a first central opening. The resin vessel includes a vessel body defining an inner edge surrounding a second central opening and a transparent sheet that closes the central opening to define a lower bound for a body of resin to be contained within the resin vessel. The one or more mechanical features are configured to align and secure the resin vessel relative to the support plate whereby the ridge engages a lower surface of the transparent sheet to tension the transparent sheet and the ridge is laterally recessed inwardly relative to the inner edge of the vessel body.