1. Towards the principle of volume 3D printing

In 1984, in the first patent concerning stereolithography , it had been possible to keep things very simple by defining layers of photopolymerizable resins, containing a photochemical initiator whose optical thickness was slightly greater than that of the layer and, step by step, achieve surface polymerization, for a given height of the object. All that had to be done was to repeat the same process to reach the final object, without then realizing that with the acrylic resins used, the oxygen present was a useful and consumable inhibitor in polymerization. Under these conditions, the surface in contact with the ambient air remained fluid...