## 3 Results and Discussion
A graphic comparison of the measured values of the Rz parameter on individual measuring lines (1, 2, and 3) and sections (A, B, and C) by the non-contact method (LPM) using laser light with different wavelengths versus the reference contact method (SJ-400) is shown in Figure 8.  
Our measurements using different laser lights in comparison with the Surftest SJ-400 contact roughness meter also showed differences in the values of the Rz parameter. The measurements indicated that even the Rz parameter values obtained by the non-contact method using different laser wavelengths (445 nm, 520 nm, and 635 nm) were higher compared with the reference values from the contact roughness meter. When using light with a wavelength of \(\lambda\) = 445 nm, we noted a 1.3- to 1.5-fold increase for Measurement Line 1, a 1.0- to 1.5-fold increase for Measurement Line 2, and a 1.2- to 1.4-fold increase for Measurement Line 3 compared with the reference values from the contact roughness gauge. We also observed similar trends for lights with a wavelength of \(\lambda\) = 520 nm and \(\lambda\) = 635 nm,  
Figure 8: Percentage comparison of the values of the Rz parameter measured by the non-contact method (LPM) using different laser lights versus the reference contact method (100%). where the values of the parameter Rz were also significantly higher compared with the reference values. When comparing the measured values of the parameter Rz obtained using a non-contact laser profilometer and the reference values from the contact roughness meter Surftest SJ-400, we also found a significant negative difference, as was the case with the parameter Ra. Although this difference in the Rz values was several times lower than the difference in the Ra parameters, we can also state that the non-contact laser profilometer method provided negative results for the Rz parameter compared with the contact roughness meter. The measured Rz values for the individual measuring lines were not evenly distributed compared with the Ra value. The differences in the values of the parameter Rz from the individual measuring lines in the cross-sectional areas of the cutting surface were caused by the laser cutting technology itself. Measuring Line 1 was characterized as a smooth area of the cutting surface, where the surface showed relatively little roughness. We also measured the highest multiple of the Rz parameter, which also resulted in the highest level of light reflection from the surface. The C1 region performed relatively better for Rz compared with the B1 region for all three laser lights. Measuring Line 2 characterized the middle area of the cutting surface, where the surface may show a slight increase in roughness compared with the smooth area, where, at the same time, the reflection of the laser light was also milder compared with that of Measuring Line 1. We can explain the reduced reflection of laser light in Part A2 as the effect of increased scoring, which was caused by the onset of the laser beam during splitting of the material. At the same time, in the given area, we also recorded an increased value of the parameter Rz during the reference measurement. Measurement Line 3 characterized a rough area of the cutting surface, which was associated with more pronounced surface unevenness and a coarser texture compared with the previous two areas, and here, the measured value of the Rz parameter was closest to the reference values too. For the Ra parameter, the best results were achieved using light with a wavelength of \(\lambda\) = 445 nm. On the other hand, in the areas C2, B3, and C3, the measured values of the Rz parameter when using light with a wavelength of \(\lambda\) = 445 nm showed relatively worse results than light with a wavelength of \(\lambda\) = 520 nm. We hypothesize that these differences were due to an increase in scoring, which was created by the interaction between the tool (for example, a laser) and the material.