Fig. 1. TSTF UCL mechanism and static volumetric 3D imaging principle. (a) TSTF UCL process of Er³⁺ ions; (b) imaging principle of static volumetric 3D display technology

Fig. 2. Example of volumetric 3D display system. (a) Right view of static volumetric 3D display system; (b) top view of static volumetric 3D display system

Fig. 3. Characterization of upconversion nanocrystals. (a) Upconversion excitation spectrum of NYF@NGF@NYF material. Monitoring wavelength is 541 nm, fixed laser source wavelength is 1550 nm, and continuous excitation source is a femtosecond laser; (b) upconversion emission spectrum of NYF@NGF@NYF material. Excitation source is infrared laser with wavelengths at 1550 nm and 850 nm; (c) addressing result in cyclohexane solutions of NYF@NGF@NYF; (d) TEM and HAADF images of NYF@NGF@NYF

Fig. 4. Basic scheme for image generation in display media

Fig. 5. Control logic of upper computer software

Fig. 6. 3D modeling and movement trajectory of slices of letter "E"

Fig. 7. Stereoscopic image display in TSTF UCL nanocrystalline solution. (a) Cylinder model displayed in nanocrystalline solution; (b) spherical model displayed in nanocrystalline solution; (c) cube model displayed in nanocrystalline solutions; (d) regular tetrahedron model displayed in nanocrystalline solutions. All photos are taken in dark