Fig. 1. Schematic diagram of the recording process of the digital holography

Fig. 2. Schematic diagram of the reconstruction process of the digital holography

Fig. 3. Flow diagram of three-dimensional pose reconstruction of the tool. (a) Tool hologram; (b) reconstruction images; (c) reconstruction images after filtering; (d) best reconstruction distance for point (i, j); (e) schematic diagram of the tool’s three-dimensional pose

Fig. 4. Schematic diagram of the digital holography experimental device

Fig. 5. Schematic diagram of the digital holographic experimental device for the lead core as simulated sample. (a) Straightened; (b) incline at a specified angle

Fig. 6. Digital hologram and reconstruction image of the lead-core. (a) Digital hologram; (b) reconstruction image (left) and calculation area magnification (right)

Fig. 7. Overall axial position distribution corresponding to (a) the local variance operator of wavelet transform and (b) local gray-scale variance operator

Fig. 8. (a) Focus evaluation curve of low frequency points corresponding to the local variance operator of the wavelet transform; (b) focus evaluation curve of the edge points corresponding to the local variance operator of the wavelet transform; (c) focus evaluation curve of the low frequency points corresponding to the local gray-scale variance operator; (d) focus evaluation curve of the edge points corresponding to the local gray-scale variance operator

Fig. 9. Three-dimensional reconstruction results of lead core. (a) Three-dimensional reconstruction results calculated by local variance operator of the wavelet transform; (b) three-dimensional reconstruction results calculated by local gray-scale variance operator

Fig. 10. Three-dimensional reconstruction results of the lead core in pixel coordinates. (a) Three-dimensional reconstruction results calculated by local variance operator of wavelet transform; (b) three-dimensional reconstruction result calculated by local gray-level variance operator

Fig. 11. Three-dimensional reconstruction results of the lead core in the distance coordinates. (a) Three-dimensional reconstruction result calculated by local variance operator of the wavelet transform; (b) three-dimensional reconstruction results calculated by local gray-level variance operator

Fig. 12. (a) Tested tool and its (b) digital hologram and (c) reconstruction image

Fig. 13. (a) Focus evaluation curve of the low-frequency point of the milling tool′s reconstruction image; (b) focus evaluation curve of the edge point of the milling tool’s reconstruction image

Fig. 14. Three-dimensional reconstruction results of the milling tool