Fig. 1. Schematic of SEM system and example of ablation imaging^[47]. (a) Schematic of in-situ laser material processing workbench, where laser sources are efficiently coupled with dual-beam SEM/FIB system through lensed fiber probes; (b) snapshots of in situ laser processing based on lensed fiber and SEM (ablation example on silicon sample)

Fig. 2. Schematic of structured light illumination super-resolution imaging in situ characterization system and SiC surface ablation imaging results^[50].(a) Schematic of the optical system combining femtosecond laser surface ablation and structured illumination profilometry for in situ monitoring of fabricated structures;comparison of (b) AFM, (c) SIP, and (d) wide-field imaging of high spatial frequency LIPSS prepared on SiC surfaces; (e)‒(g) zoomed-in plots for three modalities; (h)‒(j) measured values at three different locations in the zoomed-in plots

Fig. 3. Schematic of OCT experimental setup and reconstruction results^[51].(a) Diagram of experimental setup; (b) measured intensity spectra of SLD; (c) SEM image of two printed cubes; (d) 3D OCT reconstruction result of two cubes

Fig. 4. Schematic of conventional reflectance imaging experimental system and experimental results^[52]. (a) Schematic of the experimental setup; (b) normalized reflectance image recorded when femtosecond laser pulse excites the sapphire; (c) reflectance image and transmission interference image at 1 ps delay; (d) relative reflectance, phase change, and absorptivity at different locations at the cross section

Fig. 5. Schematic of the experimental system for ultrafast spatiotemporal imaging with a high NA objective lens and experimental results^[54].(a) Schematic of experimental setup; (b) optical micrographs of sample surface irradiated by a single pump pulse with different delay times

Fig. 6. Schematic of scattered light imaging system and experimental results^[57]. (a) Ultra-fast pumped probe imaging setup; (b)‒(m) CCD images of Zn surface with different delay times following a pump pulse at a fluence of 1.0 J/cm²

Fig. 7. Schematic of ultrafast elliptical polarization imaging system and experimental results^[59].(a) Device diagram of PPE system; (b) ablation images of molybdenum samples at different delays and angles

Fig. 8. Schematic of time-resolved LIBS device and experimental results^[60].(a) Experimental setup of time-resolved LIBS; (b) time-resolved spectral measurements (left) and time-resolved emission imaging (right)

Fig. 9. Experimental setup and results of ultrafast quasi-3D imaging^[61].(a) Experimental setup and image processing steps for ultrafast quasi-3D imaging; (b) views of ultrafast transmission, reflection dynamics, and 3D reconstruction after different fluences of laser excitation

Fig. 10. Schematic of real-time diffraction imaging system for DLIP processing and experimental results^[64].(a) Experimental setup for DLIP irradiation combined with time-resolved reflectance and diffraction measurements; (b)(c) time-resolved measurements of relative reflectance R (blue curve) and diffraction efficiency D (red curve) by DLIP irradiation at two different laser energy densities,the bottom shows the time profile and position of excitation pulse (purple curve), and the vertical dashed line indicates the curing time; (d)(e) pseudo-color plots showing the evolution of relative reflectivity R and diffraction efficiency D with time for DLIP excitation at different energy densities

Fig. 11. Schematic of SPSIM system and experimental results^[65]. (a) Schematic of surface ablation imaging process; (b) schematic of SPSLM system and optical layout; (c) original images and corresponding reconstructed surface topographies of silicon surface ablated by a single pump pulse, captured at time delays from -0.5 to 2.5 ps

Fig. 12. Schematic of CSMUP system and experimental results^[69].(a) System configuration diagram of CSMUP for femtosecond laser ablation measurements; (b) single laser ablation dynamics measurement results of silicon under 400 nm femtosecond laser irradiation taken by CSMUP

Fig. 13. Schematic of STAMP system and experimental results^[70].(a) Diagram of AOPDF-based ultrafast imaging system; (b) evolution of the shock and ionization fronts (external shock wave) as well as the contact fronts; (c) gas dynamics during laser ablation on glass

Fig. 14. System schematic and experimental results of CS-CMUI^[73].(a) Experimental setup of CS-CMUI; (b) schematic of ITO laser ablation; (c)(e) spatiotemporal intensity and phase evolution during ITO ablation; (d) relative transmittance ΔT=T (green dashed line) calculated from 2D intensity image in Fig.14(c), correlated with the corresponding result of streak camera 1D measurement (orange line)

Table 1. Spatio-temporal resolution metrics and advantages and disadvantages of various laser micro-nano fabrication characterization techniques