基于逆向空间偏移拉曼光谱技术的多层混浊样品深层分析研究

空间偏移拉曼光谱（SORS）能够准确、快速、无损检测多层混浊介质样品深层生化构成信息。该研究通过搭建集成化逆向SORS光谱分析装置，在实现逆向SORS和背散射式拉曼光谱两种不同的光谱检测模式的基础上，检测与分析了不同空间偏移量（Δs）条件下双/三层组织模型内的深层拉曼光谱信息，并根据几何光学理论和投影测量原理，量化标定了Δs与锥透镜空间位置之间的关系，这为精确控制光谱检测条件提供了保障。为了验证该装置的检测能力，采用由羊肩胛骨/对乙酰氨基酚组成的双层模型和猪皮/硅橡胶/对乙酰氨基酚组成的三层模型，获得不同Δs条件下包含样品表层和深层信息的混合光谱。并进一步对该混合光谱进行面积归一化处理，观察到随着Δs的增大样品表层的拉曼贡献逐渐减小，而第二层以及第三层的拉曼贡献逐渐增大的现象。在此基础上，通过选择模型中每层物质的拉曼特征峰计算其相对拉曼强度，分析研究了相对拉曼强度、空间偏移量与样品厚度三者之间关系，即当Δs增大时相对拉曼强度比值随之增加，这清晰地表明深层物质的拉曼强度增加。然而，在同一Δs条件下，相对拉曼强度随着表层物质厚度的增大而减小。以上实验结果表明，我们搭建的集成化逆向SORS光谱分析装置可从深度达8 mm的生物模型下获取光谱信息，并证明了该装置在经皮无损探测方面的应用价值。

Deep-Surface Analysis of Multi-Layered Turbid Samples Using Inverse Spatially Offset Raman Spectroscopy

Spatially offset Raman spectroscopy (SORS) can accurately, fast, and non-destructively obtain the characteristic spectral information from multi-layer turbid media samples. In this work, we developed and introduced a modular inverse SORS device realizing two different spectral detection modes of inverses SORS and conventional backscattering Raman spectroscopy. The deep-layer Raman spectral information from the two/ three-layer tissue model was detected and analyzed with different spatial offset value (Δs). Meanwhile, by the geometrical optics theory and the principle of projection measurement, the quantitative relationship between Δs and the axicon lens position is addressed, which supports precise controlling of the spectral detection conditions. In order to verify the system performance, a two-layer model composed of sheep scapula/paracetamol and a three-layer model composed of pig skin/silicone rubber/paracetamol were used to obtain the mixed spectra containing the constitution information of samples surface and deep layers under different spatial offsets. By performing area-under-curve normalization on the mixed spectra, it was observed that the Raman contribution of the sample surface decreases with the increase Δs value, while the Raman contribution of the second or third layers gradually increases. Moreover, for better understanding the dependence of the relative Raman intensity on the spatial offset and thickness, the relative Raman intensity is calculated by selecting the characteristic peaks of each layer in the model. The relative Raman intensity ratio increases with the increase of Δs, which exhibits an enhanced pattern of the Raman intensity. However, with the same spatial offset condition, the relative Raman intensity induces as the thickness of the first layer increases. The above experimental results testified that our developed modular inverse SORS device could obtain spectral information from a biological model with a depth of 8 mm, and manifest the application potentialities of our inverse SORS system in transcutaneous non-destructive detection.