## 3 Results and Discussion  
### Numerical Calculation Result  
In order to explore the effect of different environments on laser cleaning, laser cleaning in a water environment was further researched. Around a variety of water layer thicknesses (the same power and speed) on the cleaning effect of research, for the four conditions for analysis of 0.3 mm, 0.5 mm, 1 mm, and 2 mm, the results are shown in Figure 4.  
The findings indicate that when the water layer height was 0.3 mm, the cleaning depth achieved was 102 \(\upmu\)m, which was slightly greater than the depth of the water layer by approximately 2 \(\upmu\)m. At a water layer height of 0.5 mm, the cleaning depth increased to 110 \(\upmu\)m, exceeding the depth of the water layer by about 10 \(\upmu\)m, and significantly impacting the substratum. With a water layer height of 1 mm, the cleaning depth was 100 \(\upmu\)m, which was sufficient to achieve the desired cleaning effect, corresponding to the full removal of contaminants at the substratum level. However, there was a noticeable decrease in cleaning depth compared to the previous condition of a 0.3 mm water layer height and a cleaning  
Figure 4: Simulation diagram of water layers: (**a**) 0.3 mm; (**b**) 0.5 mm; (**c**) 1 mm; and (**d**) 2 mm.  
depth of 102 \(\upmu\)m. As the water layer height increased from 0.5 mm to 1 mm, the cleaning depth decreased to 100 \(\upmu\)m, suggesting that the optimal cleaning range lies between 0.3 and 1 mm. When the water layer height reached 2 mm, the cleaning depth was reduced to 56 \(\upmu\)m, which was inadequate to achieve the desired level of cleanliness. These changes are reflected in Figure 5.  
The results of the research surface, laser cleaning in the conditions of the water environment, in a water layer height of less than 1 mm has the effect of promoting the cleaning, which is manifested in the increase in the cleaning depth. When the height of the water layer exceeds 1 mm, the height of the water layer has an inhibiting effect on the cleaning process. The optimal water layer height is between 0.3 and 1 mm.  
The efficacy of laser cleaning was investigated across four scenarios with SiO\({}_{2}\) layers of 0.3 mm, 0.5 mm, 1 mm, and 1.5 mm thickness. The corresponding graph is presented in Figure 6 below. The analysis reveals that when a 0.3 mm layer of SiO\({}_{2}\) is added, the cleaning depth increases to 109 \(\upmu\)m, surpassing the initial 100 \(\upmu\)m, indicating an enhanced cleaning effect. With a 0.5 mm layer of SiO\({}_{2}\), the cleaning depth remains at 100 \(\upmu\)m, equivalent to the initial condition, suggesting that the cleaning effect starts to diminish at this point. As the SiO\({}_{2}\) layer thickness is increased to 1.0 mm, the cleaning depth is reduced to 86 \(\upmu\)m, which is less than the initial 100 \(\upmu\)m, signifying a suppression of the cleaning process. Finally, when the SiO\({}_{2}\) layer is increased to 1.5 mm, the cleaning depth further decreases to 65 \(\upmu\)m, indicating that the cleaning is not fully accomplished.  
The results depicted in Figure 7 indicate that when adding the SiO\({}_{2}\) active agent, the cleaning effect is best before 0.5 mm; at this time, the addition of the SiO\({}_{2}\) active agent  
Figure 5: The relationship between water layer height and removal depth.  
Figure 6: Simulation diagram of SiO\({}_{2}\): (**a**) 0.3 mm; (**b**) 0.5 mm; (**c**) 1 mm; and (**d**) 1.5 mm.  
promotes laser cleaning; when the height of SiO\({}_{2}\) active agent is more than 0.5 mm, it has already inhibited the cleaning effect.