Restoration and Spectral Recovery of Mid-Infrared Chemical Images
Restoration and Spectral Recovery of Mid-Infrared Chemical Images
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DOI：
10.1021/ac301080h
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发表时间：
2012-07-17
影响因子：
7.4
通讯作者：
Hirschmugl, Carol J.
中科院分区：
文献类型：
--
作者：
Mattson, Eric C.;Nasse, Michael J.;Hirschmugl, Carol J.
傅里叶变换红外（FTIR）显微光谱是一种功能强大的无标记化学成像技术，为各种学科的许多问题提供了有关非均匀样品的重要化学信息。最先进的基于同步加速器的红外（IR）显微光谱仪可以产生高分辨率的图像，但真正的衍射限制只有一个小的光谱范围。此外，在像素数量、采集时间和信噪比之间存在基本的权衡，限制了该技术的适用性。最近投入使用的红外同步加速器光束线，红外环境成像（IRENI），克服了这种权衡，并在一分钟内提供4096像素的衍射限制红外图像，具有高信噪比。所有中红外波长的空间过采样使IRENI数据成为空间图像恢复技术的理想选择。在这里，我们在IRENI测量并拟合了样品平面和检测器之间的74倍物镜的波长相关点扩散函数（PSF）。无噪声的波长依赖的理论PSF从在整个中红外范围（4000-900 cm（-1））内从窄带宽（4 cm（-1））生成的图像去卷积。恢复的图像的堆栈被用来重建光谱恢复的图像的金属测试样品的功能是2.5 μ m和更小的明显改善相比，原始数据图像的频率高于2000厘米（-1）。重要的是，这些空间图像恢复方法也适用于具有记录的中红外指纹区域（900-1800 cm（-1））中的振动带的样品。改进的信号-噪声光谱重建从恢复的图像所证明的球形聚苯乙烯珠在聚氨酯基质中的混合物。最后，使用新鲜解冻的视网膜组织切片来证明使用在整个中红外光谱范围内具有区别光谱特征的异质的、不规则形状的、生物相关的样品可实现的去卷积的成功。
Fourier transform infrared (FTIR) microspectroscopy is a powerful technique for label-free chemical imaging that has supplied important chemical information about heterogeneous samples for many problems across a variety of disciplines. State-of-the-art synchrotron based infrared (IR) microspectrometers can yield high resolution images, but are truly diffraction limited for only a small spectral range. Furthermore, a fundamental trade-off exists between the number of pixels, acquisition time and the signal-to-noise ratio, limiting the applicability of the technique. The recently commissioned infrared synchrotron beamline, infrared environmental imaging (IRENI), overcomes this trade off and delivers 4096 pixel diffraction limited IR images with high signal-to-noise ratio in under a minute., The spatial oversampling for all mid-IR wavelengths makes the IRENI data ideal for spatial image restoration techniques Here, we measured and fitted wavelength dependent point-spread-functions (PSFs) at IRENI for a 74X objective between the sample plane and detector. Noise free wavelength dependent theoretical PSFs are deconvoluted from images generated from narrow bandwidths (4 cm(-1)) over the entire mid infrared range (4000-900 cm(-1)). The stack of restored images is used to reconstruct the spectra Restored images of metallic test samples with features that are 2.5 mu m and smaller are clearly improved in comparison to the raw data images for frequencies above 2000 cm(-1). Importantly, these spatial image restoration methods also work for samples with vibrational bands in the recorded mid-IR fingerprint region (900-1800 cm(-1)). Improved signal-to-noise spectra are reconstructed from the restored images as demonstrated for a mixture of spherical polystyrene beads in a polyurethane matrix. Finally, a freshly thawed retina tissue section is used to demonstrate the success of deconvolution achievable with a heterogeneous, irregularly shaped, biologically relevant sample with distinguishing spectroscopic features across the entire mid-IR spectral range.