Fig. 1. Schematic diagram of scattering spectrum

Fig. 2. Brioullin scattering spectrum in different scattering regions

Fig. 3. Typical Rayleigh-Brillouin scattering spectrum: (a) In the ocean; (b) In the atmosphere

Fig. 4. Schematic diagram of approximation Gaussian fitting for Rayleigh-Brillouin in the atmosphere

Fig. 5. Schematic diagram of F-P interferometer

Fig. 6. Experimental diagram of scanning F-P interferometer for measuring Brillouin scattering in water

Fig. 7. Brillouin scattering spectrum plot obtained using scanning F-P interferometer in water

Fig. 8. Experimental diagram of atmospheric LiDAR system with scanning F-P interferometer

Fig. 9. Comparison of experimental and theoretical Brillouin scattering spectrum using scanning F-P interferometer in the atmosphere. (a) The final Rayleigh-Brillouin scattering profile;(b) Residuals between experimental measurements and Tenti S6 model

Fig. 10. Ubachs experimental results map^[54]. (a) Correlation between volume viscosity ${\eta }_{\text{b}}$ and temperature; (b) Rayleigh Brillouin scattering spectrum

Fig. 11. Schematic diagram of spectrum detection using F-P etalon combined with ICCD

Fig. 12. Brillouin scattering spectra obtained in seawater using F-P etalon combined with ICCD^[56]

Fig. 13. Experimental raw spectra and processed results. (a) Interference spectrogram collected by ICCD with actual temperature of 20 ℃ and actual salinity of 35‰; (b) Two-dimensional spectra and processing of scattering signals

Fig. 14. Error distribution graphs^[57]. (a) Measurement errors of frequency shift and line width; (b) Inversion errors of temperature and salinity

Fig. 15. Schematic diagram of atmospheric edge technology^[67]

Fig. 16. Principle and measurement results of multi-edge detection technique for wind measurement^[69]. (a) Wind measurement principle based on F–P etalon quad-edge and dual-frequency technique; (b) Radial wind speed measurement error; (c) Backscatter ratio measurement error vs. backscatter ratio

Fig. 17. Double edge technique used in Brillouin scattering spectrum. (a) Principle of double edge filtering technique^[59]; (b) Schematic diagram of the double edge underwater experimental system^[60]

Fig. 18. Temperature and salinity retrieval using double edge technique in DSSL^[60]. (a) Variation of temperature retrieval error with integration iterations (Error is less than 0.1 °C at 5000 iterations); (b) Variation of salinity retrieval error with integration iterations (Error is less than 0.5% at 5000 iterations)

Fig. 19. Schematic diagram of spectrum detection using the Fizeau interferometer combined with PMT array

Fig. 20. Schematic diagram of the laser radar system using the Fizeau interferometer combined with PMT array^[64]. (a) Schematic diagram of the underwater LiDAR system; (b) Schematic diagram of the atmospheric LiDAR System^[63]

Fig. 21. Rayleigh Brillouin scattering spectroscopy and temperature measurement results at DLR^[62]. (a) Measurement results of Raman Brillouin scattering spectroscopy at different altitudes; (b) Comparison of measured temperature (red line) with radiosonde measured temperature

Fig. 22. Temperature and pressure retrieval results based on DSSL^[50]. (a) Comparison of retrieved temperature (red line) with radiosonde measured temperature; (b) Comparison of retrieved pressure (red line) with radiosonde measured pressure

Fig. 23. Results of wind velocity and aerosol detection potential^[50]. (a) Retrieval results of wind speed variation within the altitude range of 4～9 km; (b) Retrieval results of aerosol extinction coefficient

Fig. 24. Schematic diagram of spectrum detection using VIPA. (a) Illustration of the VIPA spectral dispersing geometry; (b) A close-up illustration of the interference geometry of the VIPA

Fig. 25. Experimental setup diagram combining the VIPA interferometer with a CCD camera^[65]. (a) The schematics of the optical setup for the Brillouin spectroscopy and microscopy; (b) The VIPA spectrometer in greater details

Fig. 26. Illustration of the Brillouin spectra acquired during a spontaneous cooling process of hot water^[65]. (a) The acquired Brillouin spectra at different times; (b, c) The retrieved Brillouin shift and linewidth with and without consideration of the molecular iodine absorption; (d–f) Comparison between the Brillouin shift based on the Stokes and anti-Stokes peaks

Fig. 27. Rayleigh brillouin spectroscopy measurement results^[66]. (a) Spectra measured from 50~400 kPa; (b) Spectral profile image on the CCD camera at gas pressure of 400 kPa

Fig. 28. Temperature results measured by rayleigh brillouin scattering spectrum^[66]. (a) Retrieved temperature values (red triangle) and PT100 measured values (black star); (b) Error result