Ran Shihao, Mayerich David, Reddy Rohith
The authors are with the Department of Electrical and Computer Engineering, University of Houston, Houston, TX 77204 USA.
IEEE Photonics J. 2025 Jun;17(3):1-11. doi: 10.1109/jphot.2025.3567016. Epub 2025 May 5.
Mid-infrared spectroscopic imaging (MIRSI) enables the spatially-resolved identification of molecules and is widely used in fields ranging from biomedical diagnostics to forensics. Current MIRSI technologies measure the sample's extinction coefficient, which is only one component of the complex relative permittivity, and therefore provide incomplete molecular profiles. We propose a new framework and instrument to enable phase-sensitive that measures a sample's molecular properties at any wavelength, thus overcoming a fundamental limit on molecular specificity. Combining a spatially coherent quantum cascade laser (QCL) source with an interferometer and imaging system can provide a phase-sensitive platform for molecular analysis. This paper describes a theoretical framework for chemical holography and demonstrates benefits for molecular specificity, improved spatial resolution, and greater flexibility. Deep learning is used to solve the inverse scattering problem for chemically heterogeneous samples modeled using Mie theory. Furthermore, we demonstrate new, custom-built instrumentation and experimental results that validate our theoretical framework.
中红外光谱成像（MIRSI）能够对分子进行空间分辨识别，广泛应用于从生物医学诊断到法医学等多个领域。当前的MIRSI技术测量的是样品的消光系数，它只是复相对介电常数的一个分量，因此提供的分子特征并不完整。我们提出了一种新的框架和仪器，以实现相敏测量，即在任何波长下测量样品的分子特性，从而克服分子特异性方面的一个基本限制。将空间相干量子级联激光器（QCL）源与干涉仪和成像系统相结合，可以为分子分析提供一个相敏平台。本文描述了化学全息术的理论框架，并展示了其在分子特异性、提高空间分辨率和更大灵活性方面的优势。深度学习被用于解决使用米氏理论建模的化学异质样品的逆散射问题。此外，我们展示了新的定制仪器和实验结果，验证了我们的理论框架。
