**4. Discussions**

results of displacement are 1.25 ± 0.10, 3.01 ± 0.52, and 4.37 ± 0.58 mm for 0.5, 1.0, and 1.5 J of

phantom pendulum by a 10‐Hz Holmium laser.

lum by a 10‐Hz Holmium laser at different pulse energy level. Taking into account the mass of the stone phantom ∼2.0 g (wet and ∼1.8 g when dry), the average initial force by 10 of the

**Figure 24** reveals the average power effect of retropulsion with the 0.5‐J Holmium laser pulse train. Not surprisingly, the retropulsion increases with the average laser power applied. Apparently, the time to reach the apex increases with increasing average power. When the laser power level is increased above 25 W, the time for the phantom to come to the apex exceeds 1 s. This duration was beyond the high‐speed camera recording time in our current study. In the future, further testing should be done with increased high‐speed camera record‐

phantom pendu‐

From **Figure 22**, we can find out the initial acceleration of a 200 mm–10 mm<sup>3</sup>

100 Updates and Advances in Nephrolithiasis - Pathophysiology, Genetics, and Treatment Modalities

ing times (>1 s) to investigate the phantom dynamics at higher laser power levels.

**Figure 24.** The average power effect of retropulsion with Holmium laser 0.5‐J pulse train.

energy per pulse, respectively.

**Figure 23.** The apex of a 200 mm–10 mm<sup>3</sup>

0.5‐J pulses is 3.1 × 10−5 Newton or 3.1 Dyne.
