CAL 3D printer

Computed Axial Lithography (CAL) synthesizes arbitrary geometries volumetrically through photopolymerization. The method may be used to circumvent support structures as it can print into high viscosity fluids or even solids. Printing 3D structures around pre-existing solid components is also possible. CAL is scalable to larger print volumes, and is several orders of magnitude faster, under a wider range of conditions, than layer-by-layer methods.

CAL uses projected photons to illuminate the syrup-like resin, creating a continuously shifting video of projections as the vial rotates. Like a CT scan done in reverse, the projections combine to form a 3D object that is suspended in the resin.

The CAL manufacturing system selectively solidifies a photosensitive liquid within a contained volume. Light energy is delivered to the material volume as a set of two-dimensional images. Each image projection propagates through the material from a different angle. The superposition of exposures from multiple angles results in a three-dimensional energy dose sufficient to solidify the material in the desired shape.

A digital video projector is used to output the computed intensity-modulated projections, which are  time-sequenced to the rotation rate of the uncured photopolymer precursor material.

After the resin is exposed from all angles, the full 3D object  is materialized as a whole within the material.