## 5 Process Parameter Optimization of Laser Control System for MCR Frequency Modulation
### Laser Characteristics Analysis of MCR Frequency Modulation
The ranges of laser frequency and laser processing speed are calculated respectively. The range analysis table \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Level** & **1** & **2** & **3** & **4** \\ \hline A: Laser power/W & 6 & 7 & 8 & 9 \\ B: Laser frequency/KHz & 200 & 300 & 400 & 500 \\ C: Laser processing speed/mm/s & 200 & 400 & 600 & 800 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Factor level table. Figure 13: Experiment results of MCR frequency modulation with different parameters under the 50\(\times\) electron microscope: (**a**) 5 W, 200 KHz, 800 mm/s; (**b**) 8 W, 400 KHz, 400 mm/s; (**c**) 10 W, 500 KHz, 200 mm/s. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Experiment Number** & \multicolumn{3}{c}{**Factor Level**} & \multicolumn{3}{c}{**Evaluating Indicator**} \\ \cline{2-5}  & **A** & **B** & **C** & **Over-Frequency Rate/\%** & **Processing Time/s** \\ \hline
1 & 1 & 1 & 1 & 1.45 & 289.3 \\
2 & 1 & 2 & 2 & 1.27 & 300.8 \\
3 & 1 & 3 & 3 & 1.12 & 311.6 \\
4 & 1 & 4 & 4 & 0.98 & 323.7 \\
5 & 2 & 1 & 2 & 1.98 & 291.4 \\
6 & 2 & 2 & 1 & 1.88 & 271.2 \\
7 & 2 & 3 & 4 & 1.31 & 316.9 \\
8 & 2 & 4 & 3 & 1.51 & 303.7 \\
9 & 3 & 1 & 3 & 1.78 & 293.4 \\
10 & 3 & 2 & 4 & 1.76 & 316.2 \\
11 & 3 & 3 & 1 & 2.56 & 267.7 \\
12 & 3 & 4 & 2 & 2.22 & 281.2 \\
13 & 4 & 1 & 4 & 1.85 & 306.2 \\
14 & 4 & 2 & 3 & 2.18 & 289.3 \\
15 & 4 & 3 & 2 & 2.42 & 273.1 \\
16 & 4 & 4 & 1 & 2.85 & 259.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: L\({}_{16}\)(4\({}^{5}\)) Orthogonal experiment and results. of laser over-frequency rate and the range analysis table of laser processing time of MCR frequency modulation are listed in Tables 9 and 10. The optimal levels of laser power, laser frequency and laser processing speed on laser over-frequency rate are A1, B1 and C4, and the optimal levels for laser processing time are A4, B4 and C1. In the actual production process, to ensure that the frequency modulation completion time of each row of MCRs meets the requirements, the over-frequency rate is reduced as much as possible to cut costs. Table 1 shows that the performance index of the laser control system is that the over-frequency rate is less than 1.56% and the processing time is less than 320 s. After meeting the requirements of over-frequency rate, the shorter processing time is, the better the efficiency is. Comparing the data in Tables 9 and 10, only level 1 in factor A meets the requirement of over-frequency rate, and the levels in factor B and factor C all meet the requirement of over-frequency rate. Therefore, the results with the shortest processing time in qualified levels of A, B and C are selected as the optimal levels. In summary, the optimal levels of laser power, laser frequency and laser processing speed are: A1, B4 and C1. The variance of the influence degree of each factor is calculated by statistical analysis software, and the variance analysis results of over-frequency rate and processing time are obtained and listed in Tables 11 and 12. In the variance results of the over-frequency rate of the MCR frequency modulation, the order of F ratios is FA > FC > FB, that is, the influence of laser power on the over-frequency rate is the most obvious, followed by that of the laser \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Essential Factor**} & **A (Laser Power)** & **B (Laser Frequency)** & **C (Processing Speed)** \\ \cline{2-4}  & **Processing Time/s** & **Processing Time/s** & **Processing Time/s** \\ \hline Ki1 & 1225.4 & 1180.3 & 1087.3 \\ Ki2 & 1183.2 & 1177.5 & 1146.5 \\ Ki3 & 1158.5 & 1169.3 & 1198 \\ Ki4 & 1127.7 & 1167.7 & 1263 \\ Ki1 & 306.35 & 295.075 & 271.825 \\ Ki2 & 295.8 & 294.375 & 286.625 \\ Ki3 & 289.625 & 292.325 & 299.5 \\ Ki4 & 281.925 & 291.925 & 315.75 \\ Ri & 24.425 & 3.15 & 43.925 \\ Optimal level & A4 & B4 & C1 \\ \hline Factor primary and secondary sorting & & C > A > B & \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Range analysis table of processing time of MCR frequency modulation.