## 3 Results
### Reflectance Analysis  
The reflectance was tested before and after the Q-switched Nd:YAG laser application. The greatest decrease in reflectance coefficient is observed for the B1 color--red (Figure 6, Table 2). Before the laser application, the maximum reflectance was 1012 mW/cm\({}^{2}\)\(\times\) sr \(\times\) nm, and after dye removal was 465 mW/cm\({}^{2}\)\(\times\) sr \(\times\) nm--at a wavelength of 665 nm. In the B2 dye, a smaller decrease in reflectance was found than in the B1 dye. The maximum reflectance changed from 1150 mW/cm\({}^{2}\)\(\times\) sr \(\times\) nm to 880 mW/cm\({}^{2}\)\(\times\) sr \(\times\) nm (Figure 7, Table 2).  
Figure 5: Percentage of homogeneous areas of different sizes in images of B1–B5 dyes before and after the Q-Switched Nd:YAG laser application; * \(p<0.001\) (Chi2); ***  a fully homogeneous area for an arbitrary homogeneity criterion.  
The second largest difference in reflectance before and after the laser application applied to dye B3, in which a decrease in maximum reflectance from 1140 mW/cm\({}^{2}\)\(\times\)sr \(\times\)nm to 550 mW/cm\({}^{2}\)\(\times\)sr \(\times\)nm was observed at a wavelength of 702 nm (Figure 8, Table 2). For the B4 dye, the maximum reflectance decreased from 1110 mW/cm\({}^{2}\)\(\times\)sr \(\times\)nm to 860 mW/cm\({}^{2}\)\(\times\)sr \(\times\)nm (Figure 9, Table 2). Dye B4, among other dyes, was characterized by the smallest difference in reflectance before and after the laser application.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline  & \multicolumn{2}{c}{**B1**} & \multicolumn{2}{c}{**B2**} & \multicolumn{2}{c}{**B3**} & \multicolumn{2}{c}{**B4**} & \multicolumn{2}{c}{**B5**} \\ \cline{2-10}  & **Before** & **After** & **Before** & **After** & **Before** & **After** & **Before** & **After** & **Before** & **After** \\ \hline Maximum reflectance [mW/cm\({}^{2}\)\(\times\)sr \(\times\)nm] & 1012 & 465 & 1150 & 880 & 1140 & 550 & 1100 & 860 & 1240 & 1200 \\ \hline Decrease in maximum reflectance [\%] & 54.1 & & 23.5 & & 51.8 & & 21.8 & & 3.2 \\ \hline Wavelength at maximum reflectance [nm] & 665 & 665 & 705 & 695 & 702 & 702 & 640 & 730 & 665 & 665 \\ \hline Wavelength change at maximum reflectance & No & Yes & No & Yes & No & Yes & No \\ \hline \end{tabular}
\end{table}
Table 2: Characteristics of the B1-B5 dye reflectance curves before and after the laser application.  
Figure 6: The correlation between the reflectance and the wavelength for the B1 dye before and after the Q-Switched Nd:YAG laser application.  
Figure 8: The correlation between the reflectance and the wavelength for the B3 dye before and after the use of the Q-Switched Nd:YAG laser.  
Figure 7: The correlation between the reflectance and the wavelength for the B2 dye before and after the use of the Q-Switched Nd:YAG laser.  
Regarding B5 white dye, a minimum difference in reflectance was observed; the maximum value of coefficient decreased from 1240 mW/cm\({}^{2}\)\(\times\) sr \(\times\) nm to 1200 mW/cm\({}^{2}\)\(\times\) sr \(\times\) nm at a wavelength of 665 nm (Figure 10, Table 2).  
The maximum reflectance of all four used color dyes, B1, B2, B3, and B4, before using the laser was in the range of 1000-1200 mW/cm\({}^{2}\)\(\times\) sr \(\times\) nm (Table 2). In all four dyes, after using the laser, there was a large decrease in maximum reflectance exceeding 20% (dye B2 and B4) and 50% (dye B1 and B3) of the initial value. On the other hand, in the white dye, the initial reflectance exceeded 1200 mW/cm\({}^{2}\)\(\times\) sr \(\times\) nm, and after using the laser, the reduction of the maximum reflectance was small, amounting to 3.2%.  
The laser application caused a change in the wavelength for maximum reflectance in the two tested dyes (B2 and B4) (Figures 7 and 9, Table 2). In the B2 dye, the wavelength value was reduced from 705 nm to 695 nm for maximum reflectance, and in the B4 dye, the wavelength value was increased from 640 nm to 730 nm.