Cavity Enhanced Multi-Channels Gases Raman Spectrometer.

Raman spectroscopy has the advantages of multi-component detection, with a simple device and wide concentration ranges, and it has been applied in environmental monitoring and gas logging. However, its low sensitivity has limited its further applications. In fact, the Raman signal is not weak, but the utilization efficiency of the Raman signal is low, and most of the signal is wasted. Given this, in this paper we report a cavity-enhanced multi-channel gas Raman spectrometer with an eight-sided cuvette. First, we simulated the Raman scattering intensity at angles from 30 degrees to 150 degrees. The simulation results showed that the signal intensity at an angle of 45° is 1.4 times that observed at 90°. Based on the simulation results, we designed a three-channel sample cell for higher sensitivity. The results of these experiments showed that the sensitivity could be increased by adding all signal together, and the limit of detection (LOD) for CO2 was 75 ppm, which is better than that of each channel. This paper thus presents a new method to enhance the Raman signal, which can be used in field applications.