Fig. 1. Theory of Raman spectroscopy. (a) Schematic of the light scattering process; (b) schematic of quantum transitions during scattering

Fig. 2. Diagram of confocal Raman spectroscopy

Fig. 3. Schematic of differential confocal Raman spectroscopy^[53]

Fig. 4. Topographic imaging and Raman mapping of the IC sample^[53]. (a) Photographic microscopic image; (b) topographic image; (c) single Raman spectrum; (d) distribution of material composition; (e) shift of the Raman peak; (f) fusion of topographic image and Raman map

Fig. 5. Radially polarized pupil filtering differential confocal Raman spectroscopy. (a) Schematic of radially polarized pupil filtering differential confocal Raman spectroscopy^[58]; (b) diagrammatic sketch of the five-zone pupil filter; (c) simulation result of illumination spots of radially polarized pupil-filtering light (RPL); (d) simulation result of illumination spots of linearly polarized light (LPL); (e) normalized intensity comparision of different illumination spots of RPL and LPL^[57]

Fig. 6. Test results for electron beam lithography sample^[57]. (a) Schematic of electron beam lithography sample; (b) result measured by CRM; (c) result measured by PRDCRM; (d) result measured by SRPDCRM; (e) comparison of 240-nm periodic line contours

Fig. 7. Laser dual differential confocal Raman spectroscopy. (a) Schematic of the laser dual differential confocal Raman spectroscopy^[59]; (b) actual axial response curves of DDCM and DCM at different NA^[60]

Fig. 8. Test results of agate ore^[59]. (a) Photographic microscopic image; (b) 3D geometric morphology image; (c) fusion of topographic image and Raman map at 466 cm^-1; (d) fusion of topographic image and Raman map at 550 cm^-1

Fig. 9. Divided-aperture differential/dual differential confocal Raman microscopy^[61-62]. (a) Schematic of the divided-aperture differential/dual differential confocal Raman microscopy; (b) schematic of divided-aperture differential confocal microscopy; (c) schematic of focal spot segmentation on CCD plane; (d) schematic of the change of light spot on the CCD detection plane with sample defocus

Fig. 10. Measured results of indented single-crystal silicon^[62]. (a) Indentation morphology image; (b) Raman wavenumber mapping; (c) fusion image of the surface topographic image and the Raman wavenumber map

Fig. 11. Differential correlation-confocal Raman microscopy^[63]. (a) Schematic of the differential correlation-confocal Raman microscopy; (b)(c) comparison between differential correlation-confocal Raman microscopy (DCCRM) and confocal Raman microscopy (CRM) for axial intensity response and lateral intensity response

Fig. 12. Measured results of 4H-SiC^[63]. (a) Photographic microscopic image; (b) Raman spectra of point A, B, and C in Fig.12(a); (c) topographic image; (d) Raman intensity mapping at 779 cm^-1; (e) fusion image of topographic image and Raman intensity map at 779 cm^-1

Fig. 13. Design schematic of the laser differential confocal Raman microscopic imager

Fig. 14. Physical image of the laser differential confocal Raman microscopic imager