The temperature field induced by thermal is investigated numerically with the laminar flow pattern in the direct-liquidcooled Nd:YLF thin disk laser, since it is one of the main reasons of deformation, strain and stress. The convective heat transfer coefficient on the two big surfaces of the disk is analyzed, which affects the temperature distribution directly. The convective heat transfer coefficient is no longer the thermal boundary condition but the analysis result in the analysis process. Moreover, the influences of coolant flow velocity, deposited heat power and channel thickness on temperature field are discussed. The simulation results reveal that the temperature and the cooling capacity of coolant vary on the pump power, flow velocity and channel thickness, which have a significant contribution to the temperature gradient in the disk gain medium.
A large-aperture Nd:YLF thin disk laser oscillator is demonstrated, in which the refractive index matching liquid is used as the coolant flowing in narrow channels to cool the multiple thin disks directly. A high uniformity of pump intensity distribution is realized by using waveguides. With the a-cut Nd:YLF thin disks at different doping levels, a linearly polarized laser with the maximum output energy of 346 mJ is achieved with the repetition of 350 Hz, corresponding to an optical-optical efficiency of 8.7%, and a slope efficiency of 10%. The beam quality β factor is estimated less than 8 in the horizontal direction due to the positive branch confocal unstable resonator. To the best of our knowledge, it is the first time that the direct-liquid-cooled Nd:YLF thin disk unstable resonator is reported.
A Nd:YAG thin disk is end-pumped by two high power laser diodes and the fluid flows in a narrow channel to cool it directly. The forced convection occurs between the fluid and disk. A system is designed to measure the convective heat transfer coefficient with different flow rate. With the measured coefficient, the temperature and thermal stress in the disk are numerically analyzed. The maximum permissible thermal load is calculated, which increases with the increasing flow rate. Furthermore, the optical path different distribution is numerically calculated by considering of the thermo-optical effect, and thermal expansion at the maximum permissible thermal load. These results are useful for design of a direct-liquid-cooled Nd:YAG thin disk laser.
We have presented an innovative laser-assisted reduction surgery (LARS) based on plasma-induced ablation and photodisruption effects. In addition, we developed a laser operation system. Fetuses of mice from the Institute for Cancer Research that were immersed in physiological saline were irradiated by convergent-pulsed laser with a wavelength of 1064 nm, pulse width of 6 ns, and pulse energy of 50 mJ. The hearts of the postirradiated fetuses were significantly damaged, which resulted in rapid fetal death. We also substantiated the safety of LARS by analyzing the heat distribution of the induced laser pulse with thermal distribution equations. The results demonstrate that this innovative method for pregnancy reduction is feasible.