Environmental Microbial and Food Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, United States Department of Agriculture, 10300 Baltimore Ave., Beltsville, MD 20705 USA.
Appl Spectrosc. 2014;68(6):692-5. doi: 10.1366/13-07411.
A line-scan hyperspectral system was developed to enable Raman chemical imaging for large sample areas. A custom-designed 785 nm line laser based on a scanning mirror serves as an excitation source. A 45° dichroic beam splitter reflects the laser light to form a 24 cm × 1 mm excitation line normally incident on the sample surface. Raman signals along the laser line are collected by a detection module consisting of a dispersive imaging spectrograph and a CCD camera. A hypercube is accumulated line by line as a motorized table moves the samples transversely through the laser line. The system covers a Raman shift range of -648.7 to 2889.0 cm(-1) and a 23 cm wide area. An example application for authenticating milk powder is presented to demonstrate the system performance. In 4 min the system acquired a 512 × 110 × 1024 hypercube (56 320 spectra) from four, 47 mm diameter Petri dishes containing four powder samples. Chemical images were created for detecting two adulterants (melamine and dicyandiamide) that had been mixed into the milk powder.
开发了一种线扫描高光谱系统，以实现大样品面积的拉曼化学成像。一个基于扫描镜的定制设计的 785nm 线激光器作为激发源。一个 45°的分光镜将激光反射到样品表面，形成一个 24cm×1mm 的激发线，以正常入射。沿着激光线的拉曼信号由一个由分光成像光谱仪和 CCD 相机组成的检测模块收集。一个超立方体被逐行积累，因为一个电机化的桌子将样品横向移动通过激光线。该系统覆盖了 -648.7 到 2889.0cm(-1)的拉曼位移范围和 23cm 宽的区域。为了演示系统性能，展示了一个用于验证奶粉的应用示例。在 4 分钟内，该系统从四个含有四个粉末样品的 47mm 直径的培养皿中采集了一个 512×110×1024 超立方体（56320 个光谱）。为了检测混入奶粉中的两种掺杂物（三聚氰胺和双氰胺），创建了化学图像。
