In this technical note, we present an advanced thermospectroscopic imager based on a Fourier transform infrared (FTIR) spectrometer and a thermal camera. This new instrument can image both thermal emission and multispectral absorbance fields in a few seconds at a resolution of 4 cm-1 or less. The setup is made of a commercial FTIR spectrometer (Thermofisher Nicolet iS50R) synchronized to an IR camera (InSb and SLS) as a detector to record the interferograms in each pixel of the images. A fast Fourier transform algorithm with apodization and Mertz phase correction is applied to the images, and the background is rationed to process the interferograms into the absorbance spectra in each pixel. The setup and image processing are validated using thin polystyrene films; during this processing, more than 1750 spectra per second are recorded. A spectral resolution equivalent to that of commercial FTIR spectrometers is obtained for absorbance peaks valued less than 2. The transient capability of the FTIR thermospectroscopic imager is illustrated by measuring the heterogeneous thermal and absorbance fields during the phase change of paraffin over a few minutes. The complete mechanism of the thermochemical processes during a polymer solidification is revealed through the thermospectroscopic images, demonstrating the usefulness of such an instrument in studying fast transient thermal and chemical phenomena with an improved spectral resolution.

中文翻译：

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EXPRESS：基于热像仪的傅立叶变换红外热光谱成像仪

在本技术说明中，我们展示了一种基于傅里叶变换红外 (FTIR) 光谱仪和热像仪的先进热光谱成像仪。这种新仪器可以在几秒钟内以 4 cm-1 或更小的分辨率对热发射场和多光谱吸收场进行成像。该装置由商用 FTIR 光谱仪 (Thermofisher Nicolet iS50R) 组成，该光谱仪与 IR 相机（InSb 和 SLS）同步作为检测器，以记录图像每个像素中的干涉图。将具有切趾和默兹相位校正的快速傅立叶变换算法应用于图像，并配给背景以将干涉图处理成每个像素的吸收光谱。使用聚苯乙烯薄膜验证设置和图像处理；在此处理过程中，每秒记录超过 1750 个光谱。对于小于 2 的吸光度峰值，可获得与商用 FTIR 光谱仪相当的光谱分辨率。通过在几分钟内测量石蜡相变期间的异质热和吸光度场来说明 FTIR 热光谱成像仪的瞬态能力。通过热光谱图像揭示了聚合物固化过程中热化学过程的完整机制，证明了这种仪器在研究快速瞬态热和化学现象方面的有用性，并提高了光谱分辨率。通过在几分钟内测量石蜡相变过程中的异质热场和吸收场，说明了 FTIR 热光谱成像仪的瞬态能力。通过热光谱图像揭示了聚合物固化过程中热化学过程的完整机制，证明了这种仪器在研究快速瞬态热和化学现象方面的有用性，并提高了光谱分辨率。通过在几分钟内测量石蜡相变过程中的异质热场和吸收场，说明了 FTIR 热光谱成像仪的瞬态能力。通过热光谱图像揭示了聚合物固化过程中热化学过程的完整机制，证明了这种仪器在研究快速瞬态热和化学现象方面的有用性，并提高了光谱分辨率。