Theoretical Research on the Thermal-Lens Effect of Magnetic Fluid by Using Brownian Dynamics Method

Magnetic fluid has not only rich optical properties, but also interesting thermal-lens effect. The thermal-lens effect of magnetic fluid was studied by using the Brownian dynamics method. The Theoretical simulation and analysis were taken to research the whole generation process of thermal-lens effect. The thermal-lens effect generation of water-based magnetic fluid irradiated by the laser of different optical powers was studied in microscopic view. Based on the model of the thermal-lens effect, Monte Carlo method and Kirchhoff diffraction theory were adopted to simulate and analyze the far-field diffraction ring pattern generated by a Gauss light beam passing through the magnetic fluid. Then, the influences of different central temperatures of the magnetic fluid to the ring numbers, width, and intensity distribution of far-field diffraction ring pattern were obtained. The results were verified with the published experimental results.