Östmark Henric, Nordberg Markus, Carlsson Torgny E
Department of Energetic Materials, Swedish Defence Research Agency (FOI), Grindsjön Research Centre, Tumba, Sweden.
Appl Opt. 2011 Oct 1;50(28):5592-9. doi: 10.1364/AO.50.005592.
A Raman multispectral imaging technique is presented, which can be used for stand-off detection of single explosives particles. A frequency-doubled Nd:YAG laser operating at 10 Hz illuminates the surface under investigation. The backscattered Raman signal is collected by a receiver subsystem consisting of a 150 mm Schmidt-Cassegrain telescope, a laser line edge filter, a liquid-crystal tunable filter, and a gated intensified charge-coupled device (ICCD) detector. A sequence of images is recorded by the ICCD, where, for each recording, a different wavelength is selected by the tunable filter. By this, a Raman spectrum is recorded for each pixel, which makes it possible to detect even single particles when compared to known spectra for possible explosives. The comparison is made using correlation and least-square fitting. The system is relatively insensitive to environment and light variations. Multispectral Raman images of sulfur, ammonium nitrate, 2,4-dinitrotoluene, and 2,4,6-trinitrotoluene were acquired at a stand-off distance of 10 m. Detection of sulfur particles was done at a distance of 10 m.
本文介绍了一种拉曼多光谱成像技术，可用于远距离检测单个炸药颗粒。一台工作频率为10 Hz的倍频Nd:YAG激光器照亮被研究表面。反向散射的拉曼信号由一个接收子系统收集，该子系统由一个150毫米施密特-卡塞格伦望远镜、一个激光线边缘滤波器、一个液晶可调滤波器和一个门控增强型电荷耦合器件（ICCD）探测器组成。ICCD记录一系列图像，每次记录时，可调滤波器选择不同的波长。通过这种方式，为每个像素记录一个拉曼光谱，与可能的炸药的已知光谱相比，这使得检测单个颗粒成为可能。使用相关性和最小二乘法拟合进行比较。该系统对环境和光线变化相对不敏感。在10米的远距离处获取了硫、硝酸铵、2,4-二硝基甲苯和2,4,6-三硝基甲苯的多光谱拉曼图像。在10米的距离处检测到了硫颗粒。
