A stainless-steel micro-scanner for rapid 3D confocal imaging

Abstract

This paper summarizes the design, fabrication, and characterization of a magnetically actuated stainless-steel based micro-scanner. The out-of-plane deflection of the proposed device is calculated by using a custom depth scan setup. The main advantage of laser cutting technology, which is utilized in manufacturing the proposed steel scanner, is its rapid fabrication capability at low cost, while still offering high frequency scan for imaging and/or ablation with high frame-rates. In the lateral plane, the scanner delivers 5 degrees of total optical scan angle for a current drive of 60 mA for both slow scan and fast scan axes at 998 Hz and 2795 Hz, respectively. Furthermore, the device provides an out-of-plane pumping mode at 1723 Hz that could be utilized for axial scanning to create focal shift at the target. Fabricated scanner is integrated into a confocal microscopy setup and tested with a resolution target and a Convallaria rhizome sample, accomplishing a 240 mu m x 240 mu m field of view with 2.8 mu m resolution. The device offers 218 mu m depth of field (in tissue) and based on acquired resonance frequencies, we estimate rapid scanning of a three-dimensional block of tissue (240 mu m x 240 mu m x 218 mu m size) with approximately 3 block per second with 50% fill rate and total coverage of 87% for 1 s scan. Finally, a custom setup is proposed for 3D imaging and validity of the 3D beam steering of the micro-scanner is tested.