Fig. 1. Scattering imaging based on low-coherence spatiotemporal holographic gating technology. (a) Experimental setup; (b) Experimental results: (b1) Amplitude, (b2) Phase ^[38]

Fig. 2. Schematic diagram of digital holographic scattering imaging in turbid water. (a) Experimental setup; (b) Experimental results: Reconstruction of sperm amplitude and phase in clean water (b1), (b2) and flowing milk (b3), (b4) ^[41]

Fig. 3. Dynamic imaging optical path through scattering medium^[42]

Fig. 4. Dynamic imaging results. (a) Image of mosquito larvae observed directly in water without reference beam; (b) Image of mosquito larvae observed directly in opalescent medium without reference beam; (c) Digital hologram of mosquito larvae observed in turbid medium; (d) Corresponding angular spectrum reconstructed intensity image^[42]

Fig. 5. Schematic diagram of phase-conjugate imaging based on digital optics^[29]

Fig. 6. Schematic of the presented approach for light control between two turbid layers. (a) Schematic of experimental setup; (b) Conjugated phase map of the sample beam; (c) A quadratic phase map; (d) A pre-calculated phase map; (e) Phase diagram superimposed by (b), (c) and (d)^[44]

Fig. 7. Schematic diagram of coaxial phase-shift digital holographic 3D imaging optical system^[45]

Fig. 8. Recovered results of three-dimensional imaging based on in-line phase-shift digital holography. (a) Structure diagram of imaging target; (b) Reconstructed three dimensional slice results; Reconstructed image with a focus on (c) the grid and (d) the glass bead^[45]

Fig. 9. Recording and reconstruction of coherence holography^[52]

Fig. 10. Interferometric measurement implementation of holographic correloscopy for imaging through a scattering medium^[30]

Fig. 11. Reconstructed images. (a) Raw intensity image resulted from shearing interference in real time; (b) Fourier spectrum of the interference image and (c) Contrast image of the coherence function^[30]

Fig. 12. Schematic diagram of holographic scattering imaging based on speckle intensity correlation^[53]

Fig. 13. Experimental results. (a) Original object; (b) The autocovariance of the speckle intensity pattern and its central correlation peak are blocked; (c) Refactoring the object; (d) Original object; (e) Speckle intensity of light scattered through biological tissue; (f) The autocovariance of the speckle intensity pattern and its central correlation peak are blocked; (g) Refactoring objects^[53]

Fig. 14. Diagram of a single frame imaging technique for scattering field ^[54]

Fig. 15. Experimental results. (a) The recorded speckle pattern of the object V; (b) The recovered coaxial hologram; (c), (d) The recovered amplitude and phase distributions; (e), (f) Amplitude and phase distribution of each plane after restoration to GG1^[54]

Fig. 16. Experimental setup for phase imaging of target behind scattering medium. Laser: He-Ne laser; MO: Microscope objective; P: Pinhole; HWP: Half-wave plate; BS: Beam splitter; M: Mirror; SLM: Spatial light modulator; L₁, L₂, L₃: Lenses; GG: Ground glass; CCD: Charge coupled device^[55]

Fig. 17. Imaging performance using eight-step phase-shifting method for number 2 as test object. (a) Static conditions; (b) With vibrations; (c) Dynamic conditions^[55]

Fig. 18. Principle of ghost diffraction holography^[56]

Fig. 19. Experimental results of ghost diffraction holography (upper) and ghost diffraction holographic microscopy (down) for different scale bars. (a)-(f) 1.15 mm; (g)-(j) 34.5 μm; (k) 23.0 μm ; (l) 11.5 μm^[56]

Fig. 20. Schematics of SWH imaging through scattering media^[34]

Fig. 21. Experimental results for measurements through scatterering media. (a) Experimental optical path; (b) Imaged character U with dimensions 15 mm×20 mm; (c) Scatterers used in the imaging path: A 220 grit ground glass diffuser and a milky plastic acrylic plate of 4 mm thickness, both placed 1 cm over a checker pattern to demonstrate the decay in visibility; (d)-(g) Reconstructions of measurements taken through the ground glass diffuser; (h)-(k) Reconstructions of measurements taken through the milky acrylic plate^[34]

Fig. 22. Experimental demonstration of synthetic pulse holography. (a) Target, consisting of two characters with a longitudinal separation of 33 mm; (b)-(e) Reconstruction of the characters, using only N_Λ=1 SWL; (f)-(i) Reconstruction results when the number of synthesized wavelengths is 23; The pulse distance of the synthesized pulse train can be seen in (f) and (g)^[35]

Fig. 23. Experimental setup for the NLoS geometry. (a) Imaging schematic; (b) Picture of the experimental NLoS setup; (c) Closeup image of the rough target surface; (d) Image of the used targets: Two characters N and U with dimensions 15 mm×20 mm (plus black mountings); (e) Injection of the reference beam with a lensed fiber needle for a minimized light loss^[35]

Fig. 24. Experimental demonstration of looking around corners using SWH^[35]

Fig. 25. Applications of deep learning in digital holography. (a) Removing twin image; (b) End-to-end phase reconstruction; (c) End-to-end complex amplitude reconstruction^[72]

Fig. 26. Learning-based short-coherence digital holographic imaging ^[73]

Fig. 27. Computational holographic imaging system based on deep learning ^[74]

Fig. 28. Result of computational holographic imaging system based on deep learning ^[74]