Raman measurements using an acousto-optic tunable filter spatial heterodyne Raman spectrometer with an echelle-mirror structure

This study presents an acousto-optic tunable filter technology-based echelle-mirror spatial heterodyne Raman spectrometer (AOTF-EMSHRS) that integrates echelle gratings with mirror spatial heterodyne detection. The instrument uses the grating's high resolution and the AOTF's rapid wavelength selection capability to optimize the optical path through a mirror design. This results in a high signal-to-noise ratio (SNR), high spectral resolution, and broad wavelength range measurements. After calibration, the theoretical resolution reached 1.53 cm^-1, with a single-order spectral detection range of 1574.3 cm^-1. The spectral detection range spans from 100 cm^-1 to 4397 cm^-1. Experimentally, we detected and analyzed various organic and inorganic substances and solutions. We compared EMSHRS performances with and without the AOTF and found that the SNR of the AOTF-EMSHRS system has improved by at least twofold. Additionally, we measured solutions with different molar concentrations, various sulfate mixtures, and mixtures in transparent containers made from different materials, obtained comprehensive spectral information, and conducted detailed analyses. The AOTF-EMSHRS demonstrated excellent measurement performance during complex sample detection and analysis.