摇头丸、冰毒和海洛因等常见的毒品在特定波长激发下都可以发射荧光,但这些分子结构中的荧光基团数量较少或量子效率很低,当毒品的浓度较低时,荧光信号很弱,很难被检测到,从而限制了荧光光谱技术在毒检领域的应用。为了提高荧光光谱技术的灵敏度,从荧光信号的发散特性考虑,利用TracePro软件设计用于荧光信号收集的光路,这与传统的采用高功率激光器增加激发光能量和选用高灵敏探测器的解决方案不同;在光路中,选用抛物面型反射镜和菲涅耳透镜对不同发散角的荧光光束进行准直,采用平凸透镜和双凸透镜对光束进行缩束,采用特定尺寸的微透镜阵列对光束进行聚焦。对设计的光路进行仿真的结果表明:光路对荧光信号光的收集效率约为21.08%,比传统荧光收集光路的效率高6倍。所设计的光路可为改进本课题组已经开发的便携式高灵敏毒品荧光检测系统提供技术参考。

The narcotics such as ecstasy, methamphetamine, and heroin normally can emit fluorescence under excitation with certain wavelengths. Because of the small number of fluorescent groups in the molecular structure or the low quantum efficiency, the fluorescence intensity of narcotics is relatively weak and the narcotics with low concentration are difficult to be detected, which severely hampers the detection of the narcotics. In this paper, for improving the detection sensitivity of the fluorescence spectrum technology, the divergent characteristics of fluorescence signal are considered to increase the collection efficiency, which is different from traditional methods such as choosing high power laser to increase the excitation light energy and selecting high sensitive detector. In the optical path, parabolic mirror and Fresnel lens are used to collimate the fluorescence light, while the plano convex lens and double convex lens are used to contract the fluorescence beam, and the beam is focused by a certain size micro-lens array. Simulation results show that the fluorescence collection efficiency of the optical path is enhanced up to about 21.08%, which is six times more than that of the traditional collection method. The research work provides a technical reference for improving our portable and high sensitive narcotics fluorescence detection system.