Fig. 1. Six simulated stripe images generated by Matlab

Fig. 2. +1 order or -1 order spectrum mask screenshots corresponding to stripes in Fig. 1

Fig. 3. Picture of system used to calibrate electro-optical modulator (optical path used is marked by lines with arrows)

Fig. 4. Simplified structure of optical path of calibration system

Fig. 5. Flow chart of phase difference calculation. (a) 20 fringe images; (b) Fourier spectrum; (c) spectrum with 0 order removed in center; (d) extracted +1 order spectrum; (e) relative phase of each image calculated by cross-correlation calculation and phase-voltage fitting line

Fig. 6. Comparison of calculated results and standard values. (a) Results for 640 nm laser; (b) results for 561 nm laser

Fig. 7. Phase difference of fringes measured by contour method. (a) Fringes generated by electro-optic modulator at different voltages; (b) distribution of normalized grayscale value in underlined portion in Fig. 7(a); (c) position of lowest points in wireframe in Fig. 7(b)