High-Frequency Optical Scanner Based on Bending Vibration of Optical Fiber

Abstract

In this paper, we present a high-frequency optical scanner based on a vibrating optical fiber where the lateral displacement and rotation of the optical fiber end and the acoustooptic effect due to the stress induced in the fiber core by the vibration provide a large deflection angle of the light beam. First, the configuration used to excite high-frequency bending vibrations on the optical fiber using a piezoelectric element is described, and the relationship between the resonant frequency and the fiber length is reviewed, on the basis of the simple beam theory. Then, the principle of deflecting the light beam with the vibration and a ball lens is presented. Second, the deflection angle is estimated through the geometrical optics for the bending optical fiber, while the acoustooptic effect is simulated using the stress distribution along the optical fiber. The acoustooptic effect is observed by the stroboscope method under a microscope. The possible maximum vibration displacement was increased as the atmospheric pressure was reduced, and two-dimensional (2D) scanning was demonstrated with the fiber vibration at 42 kHz and the 0.5-mm-diameter ball lens displacement at 460 Hz.