Fig. 1. Timing diagram of Raman signal and fluorescence signal generation

Fig. 2. Typical structure of a time-resolved Raman spectrometer system

Fig. 3. PMT schematic diagram

Fig. 4. The time-resolved Raman spectroscopy system based on a photomultiplier tube built by Yaney^[27]

Fig. 5. Schematic diagram of a high-resolution full-spectrum water LiDAR based on a 32-channel PMT^[43]

Fig. 6. Schematic diagram of a 32-channel PMT^[43]

Fig. 7. Time-resolved Raman system and schematic diagram of pulses through Kerr gating^[52]. (a) Schematic diagram of the time-resolved Raman system, the red solid line represents the pump beam, the dark blue solid line represents the frequency-doubled beam, the dark blue dotted line represents the Raman fluorescence overlapped beam, and the dark blue dashed line represents the Raman light with fluorescence filtered out; (b) pulse diagram through the Kerr gate, red represents the pump light, green and blue represent the Raman and fluorescence signals, respectively

Fig. 8. Schematic diagram of the experimental setup using time-gated Raman spectroscopy to monitor methane concentration fluctuations in a local area^[23]

Fig. 9. Phase average measurement value. (a) Concentration fluctuations; (b) single side spectra of fast Fourier transform of measured concentration fluctuations

Fig. 10. The principle of time-resolved ICCD controlled by an electric field. (a) Gate on; (b) gate off

Fig. 11. Photograph and schematic diagram of the remote Raman spectroscopy system that achieves ultralong-range detection of 1752 m in sunlight^［53］

Fig. 12. Spectral data obtained by a remote Raman system for ultra long range detection at 1752 m under sunlight. (a) Remote Raman time series measurement; (b) Remote Raman spectroscopy of naphthalene at 1752 m^［53］

Fig. 13. Timeline of the development and applications of CMOS-SPAD

Fig. 14. Block diagram of time-resolved Raman spectrometer and its timing logic schematic^[95]. (a) Block diagram of a time-resolved Raman spectrometer based on a 16×256 CMOS SPAD line sensor and an integrated 256-channel 3-bit on-chip time-to-digital converter; (b) its timing logic schematic diagram

Fig. 15. SNSPD schematic diagram

Fig. 16. Equipment diagram of broadband single photon spectrometer based on Roland circle structure and single superconducting nanowire delay line^[108]

Fig. 17. Schematic diagram of a fiber-dispersed Raman spectrometer equipped with a single-photon detector^［42］

Fig. 18. Raman spectra of olivine and gypsum obtained in the time domain (bottom and middle) using a fiber-dispersed spectrometer (SNSPD) under 785 nm pulsed excitation, and the Raman spectrum of gypsum obtained in the frequency domain (top) using a grating spectrometer (CCD detector)^［42］

Fig. 19. Time gated and time integrated Raman spectroscopy analysis^［123］. (a) Spectral heatmaps collected using time gated and time integrated Raman spectroscopy; (b) the time integration and time gating techniques for catalytic testing using Pt-Sn- and Pt-based PDH catalysts, and the variation of RTR over time; (c) online GC results of catalytic testing using Pt-Sn- and Pt-based PDH catalysts

Fig. 20. Block diagram of a time-gated raman spectrometer for rapid plastic detection^［125］

Fig. 21. Spectral classification structure of one-dimensional convolutional neural network^［126］

Fig. 22. Comparison of classification accuracy of the four models before and after preprocessing^［126］

Fig. 23. Block diagram of Raman measurement setup^［97］

Fig. 24. Measurement setups of stacked layers^［97］. (a) 30-mm PMMA and 4-mm PS with an 11-mm space; (b) 3-mm PMMA and 4-mm PS with a 24.5-mm space; (c) time-domain Raman photons distribution (885 and 812 cm^-1) of the setup shown in Fig. 24 (a); (d) time-domain Raman distribution of a single point measurement of setup in Fig. 24 (b)

Fig. 25. Sample structure and time-domain distribution^[97].(a) Sample configuration of a multilayer structure;(b) time-domain distributions of Raman photons of PMMA (813 cm^-1) and PS (886 cm^-1) pieces of the configuration shown in Fig. 25(a)