A set of Raman spectrum measurement system, essentially a Raman spectrometer, has been independently designed and accomplished by our research group. This system adopts tiled-grating structure, namely two 50mm × 50mm holographic gratings are tiled to form a big spectral grating. It not only improves the resolution but also reduces the cost. This article outlines the Raman spectroscopy system’s composition structure and performance parameters. Then corresponding resolutions of the instrument under different criterions are deduced through experiments and data fitting. The result shows that the system’s minimum resolution is up to 0.02nm, equivalent to 0.5cm-1 wavenumber under Rayleigh criterion; and it will be up to 0.007nm, equivalent to 0.19cm-1 wavenumber under Sparrow criterion. Then Raman spectra of CCl4 and alcohol have been obtained by the spectrometer, which agreed with the standard spectrum respectively very well. Finally, we measured the spectra of the alcohol solutions with different concentrations and extracted the intensity of characteristic peaks from smoothed spectra. Linear fitting between intensity of characteristic peaks and alcohol solution concentrations has been made. And the linear correlation coefficient is 0.96.
Based on Mie scattering theory, this paper introduces the basic principle of aerosol light scattering and the basic calculation method of the polarization characteristics of scattering light. The spherical aerosol model is widely applied for the convenient and simple theoretic calculation, using the scattering theory by introducing the scattering amplitude matrix to combine incident radiation with scattering light. In scattering theory, aerosol extinction parameter has very important role for improving the precision of the laser radar, remote sensing detection and so on. We have mainly discussed the relationship between the spherical particle radius and extinction coefficient, and relationship between refractive index of the particles and extinction coefficient, respectively. It is concluded that extinction coefficient as a function of particles’ radius gradually oscillate approaching to 2 with the increasing of particle radius, and extinction coefficient curves as a function of refraction index have completely symmetric. The first major maximum of extinction coefficient also has obvious changes with different particles radius or refractive index.