## 3 Experimental Setup and Accuracy Evaluation of the 3D Shape Measurement
### Accuracy Evaluation of the 3D Shape Measurement  
The plane object was measured using the 3D shape measurement device. Figure 7 shows a photograph and configuration diagram of the experimental setup. The 3D shape measurement device was mounted on a linear stage. The positioning accuracy of the linear stage was 0.0001 mm. The device could be moved to any position in the \(z\) direction. A liquid crystal display (LCD) was used as a reference plane. A light diffusion sheet was pasted onto the LCD surface. The grating plate of the 3D shape measurement device was placed 700 mm away from the reference plane position at \(z\) = 0 mm. The 3D shape measurement device was moved 130 times at intervals of 1.000 mm in the \(z\) direction, and calibration was performed using the WSTM. The image resolution size was set to 552 \(\times\) 320 pixels.  
The reference plane was regarded as a plane of the measurement object after the calibration. The plane object was measured to avoid the \(z\) positions, where the reference planes were obtained, and was measured from \(z\) = 0.500 mm to \(z\) = 120.500 mm at intervals of 10.000 mm. Figure 8 shows the cross-sectional measurement results of one pixel of the 3D measurement result of the flat plane. The average value, measurement error, and standard deviation were calculated at each position (Table 3). The standard deviation of the measured value was less than 0.05 mm. The measurement error was less than 0.02 mm. The measured value was not distorted by the influence of lens aberration using the WSTM.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Camera pixel resolution (pixels) & 552 \(\times\) 320 \\ Lens focal length (mm) & 3.5 \\ Projector pixel resolution (pixels) & 1280 \(\times\) 720 \\ Grating pitch (mm) & 2.0 \\ Distance between grating and light source A (mm) & 150 \\ Distance between grating and light source B (mm) & 130 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Parameter configuration of the 3 DM-PM system.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Equipment** & **Description** \\ \hline Computer CPU & Intel Core i5-7200U 2.50–3.10 GHz \\ Computer RAM & 32 GB \\ Camera & IDS, UI-3060 CP-M-GL Rev.2 (monochrome) \\ LED source & Philips, LXZ1-PM01 (dominant wavelength: 530 nm) \\ Mapping projector & Optoma ML750 STS1 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Equipment list for the 3 DM-PM system.  
Figure 8: Measurement results of the height distribution of the plane sample.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Position \(z\) (mm)** & **Average (mm)** & **Error (mm)** & **Standard Deviation (mm)** \\ \hline
0.500 & 0.505 & 0.005 & 0.045 \\
10.500 & 10.520 & 0.020 & 0.043 \\
20.500 & 20.519 & 0.019 & 0.042 \\
30.500 & 30.516 & 0.016 & 0.041 \\
40.500 & 40.511 & 0.011 & 0.040 \\
50.500 & 50.506 & 0.006 & 0.039 \\
60.500 & 60.507 & 0.007 & 0.039 \\
70.500 & 70.505 & 0.005 & 0.039 \\
80.500 & 80.500 & 0.000 & 0.039 \\
90.500 & 90.500 & 0.000 & 0.039 \\
100.500 & 100.509 & 0.009 & 0.039 \\
110.500 & 110.509 & 0.009 & 0.040 \\
120.500 & 120.503 & 0.003 & 0.041 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Experimental results of the plane measurement.  
Figure 7: Measurement setup: (**a**) Photograph of the measuring device and the reference plane and (**b**) diagram of the measuring device and the reference plane.