Systems for preventing oxygen inhibition of a light-initiated polymerization reaction in a 3D printing system using uniform planar surfaces

A system for preventing oxygen inhibition of a light-initiated polymerization reaction at ambient conditions, said system comprising:

• a first light source for emitting ultraviolet (UV) light;
• a UV curing space for accepting a workpiece with a layer of UV curable material on the workpiece;
• means for purging oxygen from the UV curing space to facilitate, within the UV curing space, UV curing of the layer of UV curable material on the workpiece at times when the first light source emits the UV light onto the layer of UV curable material, wherein the means for purging oxygen includes a UV-transparent surface to planarize the layer of UV curable material and wherein the UV-transparent surface comprises a thin film in tension, a plate of solid material, or a combination of the thin film in tension and the plate of solid material;
• a camera arranged to evaluate reflective properties of the UV-transparent surface so as to determine whether contact has been achieved between the layer of UV curable material on the workpiece and the UV-transparent surface while the layer of UV curable material on the workpiece has not yet been cured by the first light source;
• and
• a height sensor for detecting a height of the workpiece, the height sensor comprising a second light source for emitting a beam of light and a detector for detecting the beam of light, the second light source and detector arranged on opposite sides of the workpiece and adjacent to the UV-transparent surface such that detection of the beam of light by the detector indicates that the workpiece has not yet been raised to an appropriate height for UV curing of the UV curable material to begin, and failure to detect the beam of light by the detector indicates that the workpiece has been raised to the appropriate height for the UV curing of the UV curable material to begin.