A compact optical fiber scanner for medical imaging

Abstract

A compact fiber optic scanner for biomedical applications such as optical coherent tomography has been designed, fabricated and tested. The scanner is designed as an in vivo device and composed of an optical fiber coated with nickelpowder loaded paint for external magnetic actuation. The compactness of the imaging device makes it suitable for applications where size, precision and low power consumption is critical. We have previously demonstrated the principles utilizing magnetic actuation for the fiber scanner coated with magnetic gel. This work focused on verification and optimization of the scanner operation. The magnetic properties of the nickel particle mixed with paint were characterized using an alternating gradient magnetometer. The optical scanner is externally actuated by an electromagnet and so it does not require a voltage or current supply in the probe itself. The displacements of the scanner were recorded using a position sensitive detector. The result showed a 0.8-mm displacement under the influence of a static magnetic field of 17.6 KA/m in a fiber with a moveable length of 4.2cm. Dynamic analysis showed a displacement of 0.83mm with an input current amplitude of 41mA and a magnetic field of 2.4 KA/m. The measurements are in good agreement with the theoretical lumped-element calculations. Finite-element analysis was performed and the results agree with the theoretical and experimental results. The static and dynamic displacements of the fiber optic scanner depend on the thickness and length of the magnetic coating. Thus, scanners for different displacements and operating frequencies can be designed by varying the coating thickness and length.