Fig. 1. High harmonics imaging utilizing Fresnel zone plate^[51]. (a) Experimental setup; (b) Fresnel zone plate diffraction; (c) sample image

Fig. 2. Coherent diffractive imaging. (a) Experimental setup; (b) iterative reconstruction algorithm^[64]

Fig. 3. Coherent diffractive imaging using high harmonics for the first time^[69]. (a) Experimental setup; (b1)(b2) microscopic images of the samples; (c1)(c2) collected diffraction patterns; (d1)(d2) reconstructed images; (e) intensity profile indicated by the green bar in Fig. 3(d2)

Fig. 4. Polarization contrast of nanoscale waveguides in high harmonic imaging^[76]. (a) Experimental setup; (b) scanning electron microscope image of the sample; (c1) diffraction pattern of vertically polarized harmonics at 35 nm; (c2) reconstructed intensity using diffraction data in Fig. 4 (c1); (d1)-(d4) diffraction patterns collected for different polarization and wavelengths

Fig. 5. Principle of Fourier transformation holography^[77]. (a) Sample; (b) holography; (c) other choices of references

Fig. 6. Ultrafast imaging of magnetic domains with Fourier transformation holography and coherent diffractive imaging^[83]. (a) Scanning electron microscopy of the sample; (b) experiment illustration; (c) reconstructed magnetic domains at different time delay; (d) magnetization at different time delay

Fig. 7. Ptychography using orthogonal probe relaxation. (a) Four typical probes reconstructed by the method^[95]; (b) ptychographic image of mouse hippocampal neurons^[96]

Fig. 8. Material-specific ptychographic imaging^[107]. (a1) Probe light; (a2) light field distribution behind the mask; (b) scattering quotient of a solid state disk; (c) histograms of scattering quotient distribution as indicated by the boxes in Fig. 8(b); (d1)(d2) energy-dispersive X-ray spectroscopy of the area in the dashed box in Fig. 8(b)

Fig. 9. Ptychographic imaging of highly periodic structures by vortex high harmonic beams^[109]. (a) Experimental setup; (b) diffraction pattern of vortex beams; (c) diffraction pattern of Gaussian beams; (d) ptychographic reconstruction using vortex beams; (e) ptychographic reconstruction using Gaussian beams

Fig. 10. Statistics of the reported parameters of driving laser and harmonics in high harmonics imaging experiments. (a) Wavelengths of harmonics; (b) pulse energy of driving lasers; (c) pulse width of driving lasers; (d) wavelengths of driving lasers

Fig. 11. 53 as isolated attosecond pulses measured in experiments^[13]. (a) Corrected spectrum (solid) and phase (dot); (b) time domain pulse intensity distribution

Fig. 12. Schematic diagrams of attosecond transient absorption spectrum experiment^[111]. (a) Experimental setup; (b) the level diagram and involved dynamics; (c) time-resolved transient change of optical density

Fig. 13. Single-shot femtosecond coherent diffractive imaging^[116]. (a) Scanning electron microscope image of the sample and experimental setup; (b) diffraction pattern; (c) reconstructed amplitude; (d) scanning electron microscopy image of the sample after the shot; (e) diffraction pattern of the second shot

Fig. 14. Schematics of broadband diffractive imaging

Fig. 15. PolyCDI broadband imaging^[117]. (a) Spectrum; (b) diffraction pattern; (c)reconstructed intensity

Fig. 16. Broadband coherent diffractive imaging with numerical monochromatization^[119]. (a) Spectrum; (b) broadband diffraction pattern; (c) monochromatized pattern; (d) reconstructed intensity

Fig. 17. Broadband coherent modulus imaging^[123]. (a) Experimental setup; (b) error versus bandwidth curve; (c) spectrum; (d) monochromatic coherent modulus imaging; (e) reconstructed image with monochromatic algorithm and broadband illumination; (f) broadband coherent modulus imaging results

Fig. 18. Broadband coherent diffractive imaging achieved by interferometry^[122]. (a) Experimental setup; (b) intensity of a pixel at each delay time; (c) Fourier transformation of Fig. 18(b); (d) the diffraction patterns of each wavelength obtained through analysis; (e) reconstructed object field intensity at different wavelengths

Fig. 19. Fourier transformation holography achieved by attosecond lasers^[129]. (a) Scanning electron microscope image of the sample;(b) hologram; (c) reconstructed image; (d) reconstruction algorithm

Fig. 20. Broadband ptychography with bandwidth approaching 100%^[132]. (a)-(c) Reconstructed probes at three wavelengths;(d)-(f) reconstructed sample transmission at three wavelengths; (g) measured (dash) and reconstructed (solid) spectra

Fig. 21. High harmonics imaging with Wolter mirrors^[133]. (a) Photo of Wolter mirrors; (b) spectrum; (c) experimental setups; (d) image of the sample