Aiming at the problem of oil pollution, a method based on laser Raman spectroscopy to identify oil spill is proposed in this paper. The respective Raman characteristic spectral regions were extracted from the Raman information of the biodiesel and diesel collected by the experiment. Principal component analysis (PCA) was used for identification, and partial least squares (PLS) regression was used to quantitatively analyze the mixed fuel.
Brillouin scattering lidar is a new frequency modulation detection technology, which has a broad application prospect in marine environment monitoring and underwater target detection. This paper introduces three remote sensing techniques used in practical application to realize Brillouin scattering lidar. Through the comparison of the measurement principle, measurement method and detection accuracy of three technologies, the main application characteristics of three detection techniques and the practical process in the field of ocean exploration are further understood, so as to improve the Brillouin scattering lidar system.
In order to understand the stimulated Brillouin scattering (SBS) process in water, it is necessary to analysis theoretically the factors which to determine the SBS gain coefficient and threshold. The coupled wave equation is used to investigate the effects of temperature, salinity and attenuation coefficient on SBS gain coefficient and threshold. The results indicate that the higher the temperature and salinity, the greater the SBS gain. And the threshold is negatively correlated with the temperature. The effects of attenuation coefficient on threshold of steady-state SBS is greater than transient SBS.
Measurement of sound velocity in water by Brillouin scattering method was proposed in this paper. According to the relationship between Brillouin scattering and ocean parameters, the method for measuring sound velocity by stimulated Brillouin scattering frequency shift in water was analysed theoretically and experimentally. The theoretical calculation value of sound velocity in pure water and different salinity seawater were given. Based on this, the sound velocity in pure water and 35‰ salinity seawater has been measured experimentally. The results show that sound velocity in water is obtained accurately by using Brillouin scattering and the measured results are in good agreement with the theoretical results.