Magnetic Field Modeling and Current Distribution of Magnetic-Driven Laser Steering for Endoscopic Microsurgery

Magnetic-driven laser scanner for laser steering and ablation has demonstrated its clinical significance in transoral microsurgery. However, the limited steering range restricts its usability of the magnetic laser scanner in the clinical setting. To this end, this article improves the design of the magnetic-driven scanner and expands its steering range to 11 mm x 11 mm. Compatible with the optimized laser scanner, an improved magnetic field model is established by taking both the length and thickness of the coil into consideration, and the numerical solution of the magnetic field model is derived via a Gauss-Legendre quadrature. After calibration, the proposed model appears to be consistent with the real magnetic field of the coil, which incorporates a magnetic core inside. The root-mean-squared error (RMSE) of a magnetic field model within 10-mm x 10-mm different planes is 1.3404, 4.1706, and 0.4236 Gs, respectively. In addition, the current equation is derived from the proposed model to estimate the associated current while the desired magnetic field needs to be yielded. To avoid coil overload, this article enforces the constraint of balancing current distribution to the current equation and defines the effective workspace to intuitively adjust the coefficients of the current equation. The results demonstrate that when the coefficient a(x) = a(y) = 1, the corresponding effective workspace is optimal, reflecting that the laser scanner could yield the desired magnetic field within the maximum steering range while ensuring safety.

Automated summary

This study improves the design of a magnetic-driven laser scanner and expands its steering range. A magnetic field model is established and calibrated, showing consistency with the real magnetic field. The results demonstrate the ability of the laser scanner to generate the desired magnetic field within the maximum steering range.