Abstract: Comparing with high-power laser，low-power laser is safer and its thermal lens effect is

more sen- sitive to the change of laser power，so it is more suitable for experimental teaching. In

this paper，the thermal lens effect of low-power laser is simulated by using the finite element

method，namely，the temperature field of the me- dium and the focal length of the equivalent thermal

lens are simulated，and the relationship between the focal length of low-power laser and the laser

power as well as the thermal absorption rate and thickness of the medium is quanti- tatively

explored. The simulation results are in good agreement with the experimental data，which provides a

theo- retical basis for exploring the thermal lensing effect of low-power laser.

Key words: low power laser, thermal lens effect, finite element simulation, focal length of thermal lens