Unlike point by point scanning where imaging speed and resolution compete and energy consumption is high, simultaneous irradiation of whole layers provides practically any speed and resolution using a hundred times less energy and opens the way for efficient volume production, especially of smaller parts.

To minimize slice distortion and improve layer deposition, the imager is in contact with the irradiated photopolymer and has a rigid contact surface. The main difficulties of contact irradiation, separation of imager without distorting the irradiated layer and attachment of successive layer, are resolved by using in contact with the photopolymer a material that inhibits solidification of a very thin layer in contact with it. Minimal image distortion coupled with low energy use open the way for simultaneous electronic imaging of whole layers using LCD, e.g. arrays. A number of patents in the U.S., European and other countries were granted for the processes and systems, that have been used for commercial fabrication of parts of very high accuracy and small detail since 1986.

Owing to contact irradiation, besides depositing and irradiating layers on top of the object in a polymer-filled vat, objects can be formed of stand-alone layers in air rather than in a vat. In such a system which is in the process of commercialization, layers are deposited onto the imager, and can be irradiated apart from the object and then attached to it. Efficient change of photopolymer (even from layer to layer), postcure or other processing should be possible on line.

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