基于二向色及透射准直的小型近红外拉曼光谱仪

搭建了可用于生物医学检测的小型近红外拉曼光谱仪。通过理论计算，几何光路设计，完成了系统组装。有别于传统反射式准直结构：(1)本光谱仪色散系统采用透射式准直的方法，将散射光投射到光栅上进行色散；(2)经二向色镜分光，采用物镜对入射光会聚和散射光收集，设计了与色散系统入射狭缝相匹配(共焦面)的外光路系统，进而有效收集拉曼信号和去除杂散光；(3)实现了高分辨率(3 cm-1)、高重复性和高灵敏度光谱检测，检测范围500~2 200 cm-1(785 nm激发)；(4)小型化设计，整个系统尺寸约240 mm×200 mm×130 mm，自由度高。将此自开发小型拉曼光谱仪应用于葡萄糖和膝关节软骨的拉曼光谱测试，获得了与大型商业拉曼光谱仪相媲美的结果，验证了该光谱仪具有高分辨率，高重复性和高灵敏度的优越性能，可灵活地应用于生物医学等多领域的研究。

Design and Application of Small NIR-Raman Spectrometer Based on Dichroic and Transmission Collimating

In order to meet professional requirements for the portable and high-performance Raman spectrometer, a small near-infrared (NIR) Raman spectrometer for biomedical detection was built in this work. In addition, assembly system was completed through the theoretical calculation, geometric optical path design. Differences from the traditional structure with reflective collimation were shown as below. (1) Transmission-based collimation method was adopted in dispersion system of the spectrometer, so the collimated scattering light projected onto the grating for dispersion. (2) Following dichroic mirror for reflection and penetration, objective lens converging the incident light and collecting the scattered light, the Raman spectrometer was designed to meet confocal plane at the slit between the collection unit and dispersion system, which is useful to collect the Raman signal and remove the stray light. (3) The spectrometer system achieves the high-resolution (3 cm-1), high repeatability and high sensitivity for spectral detection ranging of 500~2 200 cm-1 (785 excitation). (4) The entire optical system was designed in the size of ca. 240 mm×200 mm×130 mm, therefore achieving miniaturization for this NIR Raman spectrometer and flexible assembly of components. It was then used to measure Raman spectra of glucose and knee cartilage and get excellent results by comparing with that obtained by huge commercial Raman spectrometer. The results show that the spectrometer has high resolution, high reproducibility and high sensitivity, etc, thus it can be flexibly applied in biomedical and other research fields.