Fig. 1. Structure diagrams of commonly used DHMs. (a) Transmission DHM; (b) reflection DHM

Fig. 2. Flow chart of reconstruction of DHM. (a) Recorded off-axis hologram; (b) frequency spectrum of hologram and spectrum filtering; (c) reconstructed phase map

Fig. 3. Experimental setup of common-path simultaneous phase-shifting DHM^[36]

Fig. 4. Measurement results of phase-step with common-path simultaneous phase-shifting DHM^[36]. (a) Single-shot recorded simultaneous phase-shifting hologram (phase shift between I₁ and I₂ is π/2); (b) reconstructed phase map of phase-step

Fig. 5. Stability test results for common-path simultaneous phase-shifting DHM^[36]

Fig. 6. Schematic of DHM setup with sutructed illumination^[41]. (a) Optical setup; (b) four groups of fringe patterns loaded in SLM; (c) frequency spectrum of generated hologram with sutructed illumination

Fig. 7. Experimental results of DHM with structed illumination^[41]. (a) Recorded off-axis hologram; (b) reconstructed phase image using plane wave illumination; (c) reconstructed phase image using structured illumination; (d) phase distributions along two lines drawn in (b) and (c)

Fig. 8. Experimental results of grating topography of DHM with dual-wavelenth illumination^[45]. (a) Recorded dual-wavelength in-line hologram; (b), (c) red and blue light holograms extracted from (a); (d) reconstructed topography of grating; (e) comparison of in-line and off-axis holographic measurement results

Fig. 9. Schematic of DHM with LED illumination^[47]

Fig. 10. Comparison of experimental results on phase-step sample^[47]. (a) Recorded hologram with LED illumination (area inside white rectangular box is enlarged displayed); (b) Spatial spectral distribution of (a) (circle dashed box represents spectral filtering range); (c) reconstructed height distribution with LED illumination; (d) recorded hologram with He-Ne laser illumination; (e) reconstructed height distribution reconstructed with He-Ne laser illumination; (f) height profiles at cross sections marked with dashed lines in (c) and (e)

Fig. 11. Experimental results for autofocusing of DHM basd on structured illumination^[41]. (a) Focus criterions by amplitude variation (VAR) and proposed method; (b) reconstructed phase image with optimal focusing distance (Δz=3.2 cm)

Fig. 12. Experimental results of autofocusing using dual-wavelength diffraction difference method^[49]. (a)-(c) Differences between dual-wavelength reconstructed images with Δz=0, 7.5, and 15 cm, respectively; (d) reconstructed phase distribution of specimen for red light with Δz=15 mm; (e) comparison of evaluation function curves between different autofocusing methods