Volumetric 3D-printing (CAL)

Volumetric 3D printing: a marriage of fast and scalable to create complex multi-material constructs

The Tomolite is the first, and currently the only, volumetric 3D printer on the market. Volumetric 3D printing, also known as computed axial lithography (CAL), was invented by Taylor and collaborators at Berkeley, who published a paper on the technology in Science in 2019. In CAL, a fully three-dimensional object is built simultaneously using the same scientific approach as SLA and DLP (namely, the spatially controlled photocrosslinking of a liquid resin). However, through the combination of this approach with the principles of inverse computed tomography (CT), a three-dimensional dose distribution is simultaneously administered within the photocrosslinked resin corresponding to the desired three-dimensional geometry. As a result, the fabrication time is independent of the volume of the three-dimensional object, and centimeter-scale objects can be constructed in tens of seconds. Currently, the resolution that can be achieved is in the range of tens of micrometers, which is still slightly better than conventional 3D printing techniques. However, this is expected to improve, as the technique has only recently been introduced. Further implications of the simultaneous nature of the tomography process inherent in CAL are the fact that completely irregular geometries can be printed without the need for supporting structures, which are inaccessible via other 3D printing techniques, even with the use of supports. In addition, CAL enables the overprinting of pre-existing solid objects in a non-destructive manner, enabling the development of multi-material and multi-structure objects.