Gilbert Michael K, Vogt Frank
Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
Anal Chem. 2007 Jul 15;79(14):5424-8. doi: 10.1021/ac070518m. Epub 2007 May 26.
Spectroscopic imaging has become a widely used tool for analyses of heterogeneous samples. Focal plane array detectors are incorporated into spectrometers that acquire a large number of spectra from different sample locations in parallel. This sensing technique facilitates analyses of spatial distributions of chemical information in an X-Y plane at high time resolution. In many cases, chemical reactions proceed in three spatial dimensions (X-Y-Z) and require the acquisition of spectroscopic information in an X-Y plane plus topographic (Z-dimension) information. However, capturing two-dimensional (2D, i.e., X-Y) images from three-dimensional (3D, i.e., X-Y-Z) samples inherently loses Z-dimension information. This technical note describes an augmented spectroscopic imager that gains both types of data, i.e., spatially resolved spectroscopic information and topography. For the latter purpose, a regular light pattern is generated and projected onto a sample. Due to its 3D topography, this light pattern is distorted. After extracting these distortions, the topography can be determined since the height structure is encoded in the light pattern. Because topographic probing must not affect infrared measurements, different wavelength ranges are used. Here spectroscopic information is acquired in the mid-IR while the light pattern probing the topography is generated in the visible. For relating distortions to physical height structures, the setup needs to be calibrated. For this purpose, calibration objects of known dimensions have been manufactured onto which the light pattern is projected. Determining distortions introduced by objects of known height derives a transform from distortions to topographies. Due to mechanical restrictions, the light pattern can only achieve a certain spatial resolution. In order to enhance the spatial resolution the topography is probed with, scanning the light pattern in X- and Y-direction is proposed.
光谱成像已成为分析异质样品的一种广泛使用的工具。焦平面阵列探测器被集成到光谱仪中，该光谱仪可并行地从不同样品位置获取大量光谱。这种传感技术有助于在高时间分辨率下分析X - Y平面中化学信息的空间分布。在许多情况下，化学反应在三个空间维度（X - Y - Z）中进行，并且需要获取X - Y平面中的光谱信息以及地形（Z维度）信息。然而，从三维（3D，即X - Y - Z）样品中捕获二维（2D，即X - Y）图像本质上会丢失Z维度信息。本技术说明描述了一种增强型光谱成像仪，它可以获取两种类型的数据，即空间分辨光谱信息和地形信息。为了实现后者的目的，会生成一个规则的光图案并将其投射到样品上。由于样品的3D地形，该光图案会发生扭曲。提取这些扭曲后，就可以确定地形，因为高度结构编码在光图案中。由于地形探测不能影响红外测量，所以使用了不同的波长范围。这里在中红外波段获取光谱信息，而在可见光波段生成探测地形的光图案。为了将扭曲与物理高度结构相关联，需要对装置进行校准。为此，已经制造了已知尺寸的校准物体，并将光图案投射到上面。确定由已知高度的物体引入的扭曲，可以得到从扭曲到地形的转换。由于机械限制，光图案只能达到一定的空间分辨率。为了提高探测地形的空间分辨率，建议在X和Y方向扫描光图案。
