Theoretical Characterization of the Trapping Efficiency of Optical Tweezers for a Hollow Laser Beam

• Main Authors: Huang, Han-Ping, 黃瀚平
• Other Authors: Hsu, Long
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/87168420007952822595

碩士 === 國立交通大學 === 電子物理系所 === 98 === For a collimated laser beam normally incident into an optical tweezers system and be focused into a single particle, the axial and the transverse components of the resulting trapping force are mainly contributed by the axially outer and the central parts of the laser beam, respectively. Several demonstrations have shown that the efficiency of a trapping force can be enhanced by using a hollow laser beam. However, there is still in lack of a complete analysis on the relationship between the intensity profile of a focused hollow laser beam and the distribution of the resulting trapping force. In this paper, we simulate the spring constants of the axial and the transverse components of a trapping force as a function of the middle inclination angle and the thickness of a focused hollow laser beam, separately. The simulation result shows that the spring constants of the two components become equal as the inclination angle of a focused hollow beam is around 55° no matter how the thickness changes.