Fig. 1. Schematic diagram of glasses-free 3D imaging based on flat panel display

Fig. 2. Glasses-free 3D stereo vision schematic

Fig. 3. Schematic diagram of the surface structure distribution of the harmonic diffractive optical element

Fig. 4. Schematic diagram of the structure distribution. (a) Comparison of two-dimensional topography curves, where the blue curve is the harmonic diffraction structure, the red curve is the ordinary diffraction structure; (b) The three-dimensional topography of the harmonic diffraction structure; (c) The three-dimensional topography of the ordinary diffraction structure

Fig. 5. Light distribution of a diffractive lens. (a) Light distribution of a harmonic diffraction structure; (b) Light distribution of a common diffraction structure

Fig. 6. Beam rendering of volume pixels. (a) Schematic diagram of the three-dimensional structure of volume pixels; (b) Spectroscopic simulation of volume pixels

Fig. 7. Microscopic images of liquid crystal pixel structures

Fig. 8. Two-volume pixel light modulation diagram. (a) Spectro-optical modulation effect diagram; (b) Illuminance distribution diagram of the four viewpoints at the observation position; (c) Beam intensity curve distribution diagram of the four viewpoints at the observation position

Fig. 9. Light efficiency distribution diagram. (a) RGB tricolor light efficiency diagram and composite total light efficiency diagram; (b) Total light efficiency distribution diagram under different step approximations

Table 1. Harmonic wavelength and harmonic diffraction order

Table 2. Viewing range with a spot size of less than 8 mm

Table 3. Total luminous efficiency distribution under different step approximations