MUFF: A Low-cost Motorized Positioner Developed by Additive Manufacturing to Obtain Multi-focus Images

Multifocal microscopy is an established technique to combine several reflected-light microscopy images of an object, each with a limited depth of focus, into a single image that shows the whole object in focus. Photo-metric stereo is an independent technique to recover the third dimension of an opaque object, given several images taken from the same viewpoint with different illumination conditions. We describe a low-cost motorized positioning device for the automatic acquisition of multiple reflected-light low-power microscope images of an object for combined multifocal and photometric stereo capture of millimeter-scale objects. The device automatically varies the microscope-to-object distance and the light direction, under control of an Arduino microcontroller. The device consists of a supporting frame, a microscope holder with motorized vertical displacement, an illumination stage with multiple light sources, and control electronics. The mechanical and structural parts are largely 3D-printed. The electronics is based on the Arduino microcontroller. The device is driven through an USB cable by a Python program that runs on a PC.