Fig. 1. Optical arrangement for speckle interference deformation measurement

Fig. 2. Illustration of phase-shifter for tri-color

Fig. 3. Schematic of phase shift generating for tri-color beams

Fig. 4. Specimen production

Fig. 5. Experimental setup

Fig. 6. Wrapped phase maps of u and v components

Fig. 7. Phase distribution of same cross-section on phase maps and linear fitting results of unwrapped phase

Fig. 8. Experimental setup for measuring 3D deformation of clear aligner

Fig. 9. Color speckle pattern and its RGB components

Fig. 10. Speckle fringe patterns of deformation components at initial stage

Fig. 11. Wrapped phase related to speckle fringe patterns shown in Fig. 10

Fig. 12. Evolution of relative deformation every other 3 s of tested aligner in following 60 s

Fig. 13. Phase maps related to 3D deformation components at 60 s after loaded u， v and w obtained by ESPI

Fig. 14. Denoised phase fringe patterns shown in Fig. 13 by window-deformable adaptive filter

Fig. 15. Isoline distribution of derivatives obtained by digital differential operation on those unwrapped phase maps

Fig. 16. Three-dimensional distribution of clear aligner deflected deformation

Fig. 17. Enhanced nephogram of strain component ε_xx