How the CAL 3D printing process transforms liquids to solid objects in minutes

Science and serendipity are not always concepts that fit well together, but when it comes to the idea behind Computed Axial Lithography (CAL), it has certainly played a role. About three years ago we had the idea to adapt the principles underlying the 3D imaging technique of computed tomography to create a rapid new 3D printing technique that could fabricate objects all at once.

The idea might initially have seemed a little crazy, but when graduate student Brett Kelly brought a group of disparate experts together from the University of California at Berkeley and Lawrence Livermore National Laboratory – we realised it could actually work.

Our team was inspired by the widely used imaging technique of computed tomography, in which x-rays are projected through solid objects from many angles and software interprets the transmitted signals to build up a 3D image of what lies inside the object. We started to experiment with how we could use related principles to create tangible 3D objects by projecting patterns of light from many angles into a volume of photosensitive material. CAL was therefore, in a sense, conceived by turning the principles behind computed tomography on their head. It works by projecting a dynamically evolving pattern of light into a rotating volume of photosensitive material to form an object based on the cumulative dose of the illumination.