Design and Control of a Magnetic Laser Scanner for Endoscopic Microsurgeries

State-of-the-art surgical laser systems achieve high-quality tissue ablations with minimal thermal damage to the tissue by providing high-speed laser scanning. However, current technology is not applicable to difficult-to-reach anatomical sites for endoscopic surgery. In these cases, flexible laser fibers are used, but the resulting ablation quality is limited. Therefore, there is a need to improve flexible laser surgery systems. This paper proposes a solution to this issue based on a compact laser scanner and a focusing module designed to be placed at the distal end of a flexible endoscopic system. The device uses magnetic actuation to bend a laser fiber; thus, allowing precise 2-D position control and high-speed scanning of a high-power surgical laser. The design, implementation, and control of such a system are described in this paper, with special focus on its dynamic modeling and controller design to provide real-time control and fast automated execution of surgeon-defined trajectories. Validation experiments performed with different trajectories and scanning frequencies attest the performance of the system, which demonstrates trajectory tracing with 90 μm (1.4 mrad) accuracy for scanning frequencies up to 15 Hz. This is a significant result that promises to bring the benefits of free-beam laser scanning systems to endoscopic microsurgeries.