Towards fully 3D-printed miniaturized confocal imager

In this project a low cost, miniaturized confocal imager, consisting of 3D printed functional optical and electromechanical parts, namely, a laser scanner, a lens, and the housing is presented. The imager parts are printed from polymer material which is extremely affordable. This allows the device to be designed as disposable. The electromechanical scanning unit within the endoscopic device, having 10x10 mm2 frame size, is electromagnetically actuated in two dimensions, via a magnet that is attached to the 3D printed scanner using epoxy glue and an external miniaturized coil to work with it. 3D Printing offers extensive fabrication capabilities such as less than 20 micron resolution, processing, multi-dimensional tapering and printing hollow structures with precision. These capabilities allowed us to tailor the first two vibration modes as out-of-plane displacement and torsion movement, while pushing other undesired mechanical modes to higher frequencies. The scanner employs lissajous scan, with 180 Hz and 315 Hz scan frequencies in the orthogonal directions where we achieved ± 8° and ± 4° optical scan angles, respectively, with less than 100 mA drive current. The lens, which has a 6 mm diameter and 10 mm focal length, is 3D printed with veroclear material, then polished to obtain an optical quality surface. Polishing process was achieved in two steps which are sanding and applying an emery polisher with pressure. Surface profiler measurements, together with imaging experiments reveal only two times increase in rms roughness and a comparable focused spot diameter (less than 10% difference), as opposed to a commercial glass lens having identical structure and almost identical focal length. Scanner and lens units, together with the external coil were press-fitted into a 3D-printed housing having 17 mm width, which is comparable to many of the miniaturized MEMS based laser scanning imagers. With further development, the 3D printed confocal imager can serve as a disposable diagnostic tool for the clinic.