A spiral-like curve with an adjustable opening generated by a modified helico-conical beam

Tian Xia, Shaohua Tao, Shubo Cheng

A modified helico-conical beam (MHCB) is proposed to generate a spiral-like curve with an adjustable opening at the focal plane of a lens. Moreover, the opening of a spiral-like curve can be adjustable finely, which firstly increases quickly and then increases slowly with the increasement of the fraction n. For the MHCB, there is not also stray light around the opening at the focal plane. In addition, the intensity profile for the MHCB approaching the focal plane of the lens along the optic axis rotates. Furthermore, it is also proved in the experiments that the spiral-like beam with the opening can be used to transport particles. The generating method of the MHCB is illustrated. In addition, we also prove numerically and experimentally that the MHCB can produce a spiral-like intensity distribution. The proposed beam can be applied to induce transportation of particles, and collect multiple particles in the center of the spiral-like curve, and sort the particles into different positions.

DOI