Experimental Research On And Theoretical Analysis Of Trapping Force On A Particle For Optical Tweezers

In this thesis, the optical tweezers technology is introduced here. By using of optical tweezers, we could catch particles and moved them in three-dimensional. The experiment for optical tweezers is designed and built up. The phenomena of light scatting by polystyrene spherical particle is observed. And the polystyrene is caught by the focusing Gaussian beam. The principle of optical tweezers is discussed, and radiation trapping forces for particles are calculated. The generalized Lorenz-Mie theory(GLMT) is used here to calculate the trapping forces of the focusing Gaussian beam on a spherical particle. We discussed the influence of different parameter, such as beam waist radius and power of the laser, on trapping forces. The influences on the axial and transverse radiation trapping forces by such parameters are also analyzed here. The numerical simulation is given to analyze the trapping of multilayered spherical particle with different absorbing coefficients and relative refractive indexes distributing.