The Study Of The Radiation Forces Exert On The Rayleigh Particles By The Laser Beam

Laser trapping is an advanced technique that utilizes radiation forces to trap and manipulate microscopic particles. Optical tweezers, also known as single beam gradient force optical trap, rely upon the extremely high gradient in the electric field produced near the beam waist of highly focused laser beam, which creates Pico-Newton force sufficient enough to trap small particles in three dimensions. With the development of science and technology, in the past several years, different new types of complex laser beams are researched to exert on microscopic particles. In this thesis, the background and the historical significance of the laser manipulating particles, the progress in the field of optical tweezers are introduced. In the second chapter, the definition of optical tweezers, the principle of optical tweezers and the three basic models of optical tweezers are introduced. In the third chapter, based on the Rayleigh regime, the basic theory of radiation force exerted on dielectric microscopic particles in the Rayleigh regime is introduced. Based on the propagation properties of the anomalous hollow beam, the radiation force produced by the anomalous hollow beam on the dielectric particle is calculated. Also we analyzed the radiation force exert on the metallic particles by the focused Gaussian beam. Finally, the experiment set up of the optical tweezers has been reviewed, we analyze the requirement of apparatus for the set up of optical tweezers, the experiment set up of optical tweezers has been successfully established and the glass particles have been stably trapped by using the 1064nm laser, some important results have been obtained.