Generation of a ring-shaped focusing spot with precisely controllable position and diameter

Jiannong Chen, Chenglong Zhao, Dawei Zhang, Bo Dai, Linwei Zhu, and Qinfeng Xu

Ring-shaped focusing spots play a critical role in double beam super-resolution fluorescence imaging and can also be used in single beam optical trapping. The alignment and size matching of two beams is a significant issue in a double beam application and a transversely movable and diameter-controllable ring-shaped focusing spot is very useful in single beam trapping. Until now, however, the size and the position of the ring-shaped focusing spot in the focal plane could not be precisely controlled. Here, we demonstrate that a ring-shaped focusing, circularly symmetrical spot with a controllable position and an adjustable diameter can be generated in the focal plane of a high numerical aperture objective. The ring-shaped spot is composed of equally spaced multiple spots with small enough diameters arranged on the circumference of the ring. By updating the phase modulation, we also demonstrated the dynamic manipulation of the yeast cell in the focal plane with this controllable ring-shaped spot.

DOI