Fig. 1. Schematic of the measuring device. (a) Single camera multispectral measurement system; (b) traditional four-camera measurement system

Fig. 2. Refraction correction model

Fig. 3. Flow chart of system calibration and 3D reconstruction

Fig. 4. Schematic of strain measurement along thickness direction. (a)(b) Local coordinate system and its enlarged view; (c) front and back surfaces with the same calculated areas

Fig. 5. Thin plate morphology. (a) Three-dimensional morphology of 3.3 mm thin plate; (b) three-dimensional morphology of 4.3 mm thin plate; (c) semi-cylindrical three-dimensional morphology

Fig. 6. Experimental setup diagram. (a) Experimental setup; (b) experimental specimen

Fig. 7. Real time speckle image. (a) Color image; (b) blue and red channel subimages; (c) two subimages of the left image; (d) two subimages of the right image

Fig. 8. Full-field strain along thickness direction. (a) Strain distribution along thickness direction at T₁=153 s; (b) strain distribution along thickness direction at T₂=173 s; (c) strain distribution along thickness direction at T₃=193 s

Fig. 9. Trend of strain variation along thickness direction. (a) Distribution of calculation points; (b) strain-time curves along thickness direction