Transient Thermal Lens Simulation of Ho:YAG Laser - Abstract
Abstract The Ho:YAG laser has been the favored lithotripter for the treatment of urinary calculi since shortly after its introduction in the 1990s, because it can fragment all calculus compositions and produces less calculus migration (retropulsion) during treatment than the short-pulsed lasers [Marks AJ et al., World Journal of Urology. 2007; 25(3): 227]. Although the lamp-pumped Ho:YAG laser has been commercialized for ureteroscopic laser lithotripsy (URSL) for almost 25 years, the transient thermal behavior of the lamp-pumped laser rod is difficult to estimate. The objective of this study is to simulate the transient thermal behavior of the lamp-pumped laser rod from preheating to laser operation. The temperature profile inside the laser rod is transformed into an equivalent thermal lens, and from the time interval of the variation of the thermal lens between lasing threshold and the maximum value of stable region, we can estimate the level of the laser output. The simulation tool used for this study is the Ansys Fluent, and the transient thermal behavior of the lamp-pumped laser rod from preheating to laser operation was reported. Optimization of the pumping pulse for the desired laser output pulse is for a future study.