Tran C D, Cui Y, Smirnov S
Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, USA.
Anal Chem. 1998 Nov 15;70(22):4701-8. doi: 10.1021/ac980647q.
A new multispectral imaging spectrometer capable of simultaneously recording spectral images in the visible and near-infrared has been developed. In this instrument, an acoustooptic tunable filter is used to diffract an unpolarized incident light into two diffracted beams with orthogonal polarization; one of them is detected by a silicon camera for the visible region while the other beam is detected in the near-infrared region (from 1 to 1.7 microns) with a NIR camera. The imaging spectrometer is sensitive, inexpensive, and field deployable because it is based on the recently available InGaAs focal plane arrays camera, which is low cost and can be sensitively operated at room temperature. Preliminary applications of the imaging spectrometer include measurements of the visible and NIR absorption spectra of ink used to print U.S. currency. Such results may help to characterize samples as well as to control and to ensure the quality of the samples during the production processes. More important are the results obtained on ethylene/vinyl acetate copolymers. The NIR spectral images obtained clearly indicate that these copolymers exhibit a high degree of chemical inhomogeneity. Because of the possibility of inhomogeneity, it is very important that the homogeneity of polymers or copolymers be thoroughly understood before the NIR methods, especially those based on NIR spectrometers equipped with a single-element detector, are used for measurements.
一种能够同时记录可见光和近红外光谱图像的新型多光谱成像光谱仪已被研制出来。在该仪器中，一个声光可调滤光器用于将非偏振入射光衍射成两束具有正交偏振的衍射光束；其中一束由硅相机用于可见光区域的检测，而另一束光则由近红外相机在近红外区域（1至1.7微米）进行检测。该成像光谱仪灵敏、价格低廉且可现场部署，因为它基于最近可得的低成本且能在室温下灵敏运行的铟镓砷焦平面阵列相机。该成像光谱仪的初步应用包括对用于印刷美国货币的油墨的可见光和近红外吸收光谱的测量。这样的结果可能有助于对样品进行表征，以及在生产过程中控制和确保样品的质量。更重要的是在乙烯/醋酸乙烯酯共聚物上获得的结果。所获得的近红外光谱图像清楚地表明这些共聚物表现出高度的化学不均匀性。由于存在不均匀性的可能性，在使用近红外方法，尤其是那些基于配备单元素探测器的近红外光谱仪的方法进行测量之前，充分了解聚合物或共聚物的均匀性非常重要。
