The Influence of the Focus on the Counter-Propagating Optical Trapping

In our research, compared to conventional counter-propagating optical trapping setup, another CCD is used to help detect the focus in the XZ plane and thereby improving accuracy of the setup. Then we use this setup to accurately regulate three types of focus in counter-propagating dual beam optical trapping. Finally, some micron sized polyethylene particles are utilized to demonstrate the difference of these three types of focus. Therefore, we believe our work is beneficial to help explore the problem in counter-propagating optical trapping.