A dual-wavelength rapid excitation Raman difference spectroscopy (DWRERDS) system for separation of Raman signals from background interference was developed. In the DWRERDS system, a dual-wavelength diode laser at 784.59 and 785.22 nm with volume Bragg gratings was used as the excitation light source. For each laser line, optical power could reach as high as 550 mW. Under dual-wavelength excitation mode, the DWRERDS system could switch each laser instantaneously and the excitation time of each laser was as short as 1 s. Two Raman spectra were measured with slightly shifted excitation wavelengths and subtracted from each other, resulting in a background-free difference spectrum. The DWRERDS system was applied to complex matrix background suppression, which could improve a very good signal-to-noise ratio (SNR) for Raman spectra. Although ethanol in Coca-Cola could not be detected by conventional Raman spectroscopy, the DWRERDS system could be used for the direct detection of ethanol in illegal alcoholic beverages. The experimental results showed that the limit of detection (LOD) of ethanol in Coca-Cola was volume percentage of 4.76% and the correlation coefficient for the linear regression was as high as 0.984. The DWRERDS system could be used to determine the concentration of ethanol in illegal alcoholic beverages within 1 min without any sample pretreatment.

开发了一种用于从背景干扰中分离拉曼信号的双波长快速激发拉曼差分光谱 (DWRERDS) 系统。在 DWRERDS 系统中，具有体积布拉格光栅的 784.59 和 785.22 nm 双波长二极管激光器用作激发光源。对于每条激光线，光功率可高达 550 mW。在双波长激发模式下，DWRERDS系统可以瞬间切换每束激光，每束激光的激发时间短至1 s。两个拉曼光谱是在激发波长略微偏移的情况下测量的，并相互减去，从而产生无背景差异光谱。DWRERDS 系统应用于复杂基质背景抑制，可以提高拉曼光谱的非常好的信噪比（SNR）。虽然传统拉曼光谱无法检测可口可乐中的乙醇，但 DWRERDS 系统可用于直接检测非法酒精饮料中的乙醇。实验结果表明，可口可乐中乙醇的检出限（LOD）为体积百分比4.76%，线性回归相关系数高达0.984。DWRERDS 系统可用于在 1 分钟内确定非法酒精饮料中的乙醇浓度，无需任何样品预处理。76%，线性回归的相关系数高达 0.984。DWRERDS 系统可用于在 1 分钟内确定非法酒精饮料中的乙醇浓度，无需任何样品预处理。76%，线性回归的相关系数高达 0.984。DWRERDS 系统可用于在 1 分钟内确定非法酒精饮料中的乙醇浓度，无需任何样品预处理。