When you think of CT — computed tomography — scanning, your mind automatically jumps to a medical imaging technology that uses a series of X-rays fused together to form a 3D model of a person. This technique can also be accomplished with visible light using the same sort of approach, as long as the object is semi-transparent. While this puts some limits on the method, it produces really excellent images of objects like tomato slices, shown in Jon Bumstead’s project write-up about his DIY visible CT rig.
Bumstead’s device uses an LED array to illuminate the object and a camera with a telecentric lens is placed on the other side of it to capture light shining through. This specialized lens receives light without distortion based on distance. A stepper motor is then used to rotate the object, and the process is repeated many times until a full scan is taken.
Since the principle used here is almost exactly like a 3D scanner, Bumstead’s also affixed a light on the same side as the camera to enable it to do this as well.
The CT scanner is controlled via an Arduino Nano, which triggers the camera at the right time, and allows for a nice user interface with buttons an an LCD screen. From here, the resulting image data is fused together to produce CT or surface 3D scan results.
Be sure to check out the video below for a great explanation on the build, as well as footage of the device in action around 10:00.