The field of biomedical imaging has undergone a rapid growth in recent years, mostly due to the implementation of ad-hoc designed experimental setups, theoretical support methods and numerical reconstructions. Especially for biological samples, the high number of scattering events occurring during the photon propagation process limit the penetration depth and the possibility to outperform direct imaging in thicker and not transparent samples. In this thesis, we will examine theoretically and experimentally the scattering process from two opposite points of view, focusing also on the continuous stimulus offered by the will to tackle some specific challenges in the emerging optical imaging science. Firstly, we will discuss the light propagation in diffusive biological tissues considering the particular case of the presence of optically transparent regions enclosed in a highly scattering environment. The correct inclusion of this information, can ultimately lead to higher resolution reconstruction, especially in neuroimaging. On the other hand, we will examine the extreme case of the three-dimensional imaging of a totally hidden sample, in which the phase has been scrambled by a random scattering layer. By making use of appropriate numerical methods, we will prove how it is possible to outperform such hidden reconstruction in a very efficient way, opening the path toward the unexplored field of three-dimensional hidden imaging. Finally, we will present how, the properties noticed while addressing these problems, leaded us to the development of a novel alignment-free three-dimensional tomographic technique that we refer to as Phase-Retrieved Tomography. Ultimately, we used this technique for the study of the fluorescence distribution in a three-dimensional spherical tumor model, the cancer cell spheroid, one of the most important biological model for the study of such disease.
Free-electron laser-based extended wide-field mid-infrared photothermal imaging for biomedical and microplastic analysis
Leibniz Institute of Photonic Technology（莱布尼兹光子技术研究所）；Research Center Borstel, Leibniz Lung Center（博斯特尔研究中心，莱布尼兹肺科中心）；German Center for Infection Research (DZIF)（德国感染研究联合会）；Jena University Hospital（耶拿大学医院）；Helmholtz-Zentrum Dresden Rossendorf（德累斯顿-罗斯多夫亥姆霍兹中心）；Friedrich-Schiller-University Jena（耶拿弗里德里希·席勒大学）
An unambiguous derivation of the effective refractive index of biological suspensions and an extension to dense tissue such as blood
van de Hulst公式提供了光学均匀介质中任意形状、尺寸和折射率的颗粒悬浮液的有效折射率或有效传播常数的表达式。然而，其有效性的生物物质，其中往往是非常密集的细胞悬浮液，是不清楚的，因为现有的公式推导或类似的结果依赖于远场散射和/或悬浮液的问题是稀释。我们提出了一个推导的van de Hulst公式有效的悬浮液的大，纤细的散射体-类型的生物悬浮液通常由-这并不依赖于这些条件，表明它们不是严格必要的公式是有效的。我们将这些结果专门应用于血液和上皮组织。此外，我们确定的真正条件的公式是有效的这些类型的组织。最后，我们提供了一种简单的方法来估计--更重要的是，纠正--当不满足此条件时van de Hulst公式所产生的误差。
First-principles calculations of Raman vibrational modes in the fingerprint region for connective tissue
振动光谱学已被广泛用于揭示生物系统的物理化学性质。由于其对监测实时“原位”变化的高灵敏度，拉曼光谱已被成功地采用，例如，在生物医学、代谢组学和生物医学工程方面。在这些情况下，拉曼光谱解释的基础是孤立的大分子组成振动分配。因此，探测特定部分/侧链之间的非谐相互作用或相互作用是一个挑战。我们提出了一个完整的振动模式计算结缔组织的指纹区域（$800-1800$ cm $^{-1}$）使用第一性原理密度泛函理论。我们的研究结果表明，重要的光谱特征相关的分子特征已被忽略在通常的组织光谱波段分配。特别是，我们发现，承压水的存在是主要负责所观察到的光谱复杂性。我们的计算占在这一地区的光谱特征的固有复杂性和有用的生物过程的光谱标记明确确定。
A New Continuum-Based Thick Shell Finite Element for Soft Biological Tissues in Dynamics: Part 1 - Preliminary Benchmarking Using Classic Verification Experiments
Single-channel and multi-channel electrospinning for the fabrication of PLA/PCL tissue engineering scaffolds: comparative study of the materials physicochemical and biological properties
A New Continuum-Based Thick Shell Finite Element for Soft Biological Tissues in Dynamics: Part 2 - Anisotropic Hyperelasticity and Incompressibility Aspects
