Salinity is one of the important physical parameters in oceanography. Current methods for remote sensing of ocean salinity are based on the monotropic function between Raman spectra and ocean salinity, while the effect of the ocean temperature, which influences the measurement of salinity, is neglected. Therefore, this paper proposes a method for fine inversion of salinity combining Brillouin and Raman spectra of water. The Raman spectra of solutions containing a single solute and mixed solutions were detected, and the effect of solutions containing different solutes on the spectra was analyzed. The experimental results revealed the variation in the low- and high-frequency spectral intensities of the Raman spectra with salinity and temperature. The Raman spectra of seawater were modeled as a function of temperature and salinity using the low- and high-frequency area ratios. Brillouin scattering spectra are also related to ocean temperature and salinity, changes in temperature and salinity will affect the frequency shift and line-width of Brillouin scattering spectra. Based on the Brillouin scattering theory, the relationship between frequency shift and line-width with ocean temperature and salinity was analyzed. With high spectra resolution lidar as the detection technique, the Brillouin frequency shift, line-width and Raman spectra of ocean could be detected simultaneously by using multi-beam interferometry, photon correlation spectroscopy, and Raman spectra detection techniques. A high precision inversion model of ocean salinity can be obtained by using a multi-source data fusion. This research will provide reliable data for the study of global climates and ecosystems and improve the accuracy of marine disaster warnings and marine weather forecasting.
In the detection of atmospheric temperature profile by Rayleigh scattering, the influence of Brillouin scattering is usually ignored and the accuracy of temperature detection is reduced. Current researches on Brillouin scattering are mainly focusing on hydrodynamic and Knudsen regime, few researches has been done on the kinetic regime. In order to improve the precision of atmospheric temperature measurement, a mathematical model based on three Gussian distributions was adopted to study the Rayleigh-Brillouin scattering spectrum (RBS) in kinetic regime, the mixed Rayleigh and Brillouin signal in atmospheric echo signal is separated to obtain independent Rayleigh and Brillouin spectrum. Finally, the experimental platform was set up to control simulation of atmospheric environment system and establishes a hyperspectral splitting optical system based on Fabry-Perot interferometer. The spectrum obtained by the experiment was used to optimize the mathematical model and improve the detection accuracy of atmospheric temperature profiles.
Light emitting diodes (LEDs) have recently gained much interest as projection light sources. In this work, a compound parabolic concentrator (CPC) coupled to a biologically inspired compound-eye array is designed and fabricated as a light collection engine of a pico-projector. The results indicate that more than 90% light emitted by a monolithic LED array can be collected by the CPC coupled to a compound-eye array and transmitted within the designed angle. This method is advantageous in many respects compared with those available, such as compact volume, high collection efficiency, rectangular radiation pattern and controllable output divergence angle. The result validates that the system reaches a collection efficiency of 87% of micro-LED emitted light. Moreover, the beam collimation quality has been analyzed obtaining a residual divergence of less than 2º. Thus, the results achieved by the proposed optical system improve those obtained with several commercially available devices.
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