Laser self-induced thermo-optical effects in a magnetic fluid

The laser self-induced thermo-optical effects in a magnetic fluid are studied in this work. We study the origin of these effects theoretically, and then experiments are done to investigate the relationship between the divergence angle of the laser beam and the incident power. From the experimental results, we find out that the divergence angle increases linearly with the incident power to some critical power, which is in good agreement with the theory. To the high incident power side, the divergence angle will deviate from the linear relationship and the spherical aberration interference rings will be blurred due to the occurrence of the convective currents.