Super-resolution optical microscopy using transmissive micro structures

高分辨率的物体细节检查对于许多研究、开发和制造领域都是必不可少的。一个简单的选择是经典光学显微镜。然而，这种方法的分辨率受到阿贝描述的分辨率极限的限制。因此，过去已经一次又一次地研究了克服这种限制的方法。提高分辨率的一种方法是将微球施加到物体的表面。可实现的分辨率基本上取决于微球的直径以及微球与周围介质之间的折射率差。在文献中，用标准光学显微镜分辨分离<100 nm的物体，这对应于远小于波长的分辨率。目前，还没有通用的模型来解释这种实验观察到的效果。然而，一个广泛的理解是必不可少的评估的限制和潜力的方法，以及优化所使用的微结构的成像性能。在文献中，实验数据仅限于球形微结构的研究，既没有显示无失真的图像，也没有更大的视野。对于偏离球形的微结构的研究仅限于对它们的聚焦特性的模拟;实验结果是不可用的。因此，建议的项目有两个目标：1.发展一个理论模型来解释阿贝衍射极限以下的分辨率（以下称为超分辨率）的影响：与文献相反，这里提出的模型不是基于麦克斯韦方程的解，而是基于标量衍射理论的更简单的原理，特别是为了理解超分辨率的影响而扩展的惠更斯-菲涅耳方法。此方法将在项目中采用，以一种简化的方式来描述耦合到微结构的倏逝场。上面概述的过程导致计算时间的减少，并允许根据成像特性对微结构进行迭代优化。2.理论研究结果的实验实施：虽然在文献中，到目前为止，只有球形结构进行了实验研究，非球面结构仅通过模拟描述，但在我们的建议中，球体和自由形状的微结构通过直接激光写入制造，光学表征，并以这种方式验证超分辨率的效果。因此，拟议的项目使人们有可能获得一个良好的理论理解，以解释超分辨率的效果。这也为利用激光直写制作球面和非球面微结构的超分辨光学显微镜的应用带来了实际的可能。

The examination of object details with high resolution is essential for many areas of research, development and fabrication. A simple option is the classical light microscopy. The resolution of this approach is, however, restricted by the resolution limit described by Abbe. Therefore, approaches have been investigated again and again in the past to overcome this limit. One way to increase the resolution is the application of microspheres to the surface of the object. The achievable resolution essentially depends on the diameter of the microsphere and the refractive index difference between the microsphere and the surrounding medium. In the literature, objects with a separation <100 nm were resolved with a standard light microscope, which corresponds to a resolution much smaller than the wavelength. Presently, no general model is available to explain this experimentally observed effect. However, a broad understanding is essential for the evaluation of the limits and potential of the method as well as for optimizing the imaging properties of the microstructures used. In the literature, experimental data are limited to studies on spherical microstructures, which neither show distortion-free images nor larger fields of view. Investigations of microstructures that deviate from a spherical shape are limited to simulations of their focussing properties; experimental results are not available.Therefore, the proposed project has two objectives: 1. Development of a theoretical model to explain the effect of a resolution below the Abbe diffraction limit (in the following termed super-resolution): In contrast to the literature, the model proposed here is not based on the solution of Maxwell's equations, but on the simpler principles of scalar diffraction theory, specifically an extended Huygens-Fresnel approach in order to understand the effects of super-resolution. This approach will be employed in the project to describe the coupling of evanescent fields into the microstructure in a simplified way. The procedure outlined above leads to a reduction of the computation time and allows an iterative optimization of the microstructures in term of imaging properties. 2. Experimental implementation of the theoretical findings: While in the literature so far only spherical structures were investigated experimentally and aspheric structures were only described by simulations, in our proposal spheres and freeform-microstructures are fabricated by direct laser writing, optically characterized and in this way the effect of the super-resolution will be verified. The proposed project thus makes it possible to obtain a well-grounded theoretical understanding to explain the effect of super-resolution. It also brings the super-resolution optical light microscopy using spherical and aspherical microstructures fabricated by direct laser writing to a practical application.