Journal of Modern Optics   2016 年 63 卷 16 期

2016.03.15

It is popularly believed that when the focal spot is shifted far away from the optical axis of optical system with the pupil filter, it will be significantly aberrated. Therefore, the pupil filter is usually only used to adjust the distribution of the focal spot at the optical axis of optical system. In this paper, the special combination of the phase pupil filter shifting the focal spot and the high-pass filter eliminating the aberration of the focal spot is designed so that the focal spot can be shifted dynamically at the focal plane. By utilizing the Debye vector diffractive theory, the shifting behaviours of the focal spot are investigated in detail. The proof-of-principle experiment demonstrates the validation of the method for dynamically controlling the position of focal spot. This work is helpful to realize dynamically shifting the focal spot with the pupil filter and may find valuable applications in particle trapping, microscopes, optical engineering, and so on.