Fig. 1. Schematic diagram of SLM filling structure

Fig. 2. Schematic diagrams of orthogonal phase grating.(a) Radial binary grating; (b) axial binary grating; (c) orthogonal phase grating

Fig. 3. Profile of orthogonal phase grating

Fig. 4. Orthogonal phase grating structure diagrams. (a) Orthogonal phase grating; (b) element structure of orthogonal grating

Fig. 5. Orthogonal grating results and their diffraction light intensity. (a) Orthogonal phase grating; (b) diffraction pattern of orthogonal phase grating

Fig. 6. Schematic diagrams of orthogonal phase grating with different grey levels. (a) Structural diagram of orthogonal phase gratings with different gray grades; (b) one-dimensional distribution of orthogonal phase grating

Fig. 7. Orthogonal phase gratings with different period and corresponding diffraction patterns. (a) Orthogonal phase gratings with different periods; (b) diffraction patterns corresponding to orthogonal phase gratings with different periods

Fig. 8. Orthogonal phase gratings with different phase modulation depth and corresponding diffraction patterns. (a) Structural diagrams of orthogonal phase gratings with different phase modulation depths; (b) diffraction patterns corresponding to orthogonal phase gratings with different phase modulation depth

Fig. 9. Variation of relative intensity of different diffraction orders varying with grey level

Fig. 10. Variation of diffraction efficiency of 1st order light varying with grey level

Fig. 11. Experimental results of diffraction for orthogonal phase gratings with different phase modulation depth

Fig. 12. Experimental results of relative intensity of different diffraction orders varying with grey level

Table 1. Intensity of different orders calculated by Eqs. (9)-(11) and Fourier transform

Table 2. Intensity of zero-orders calculated by Eq. (18) and experiments