Super-resolution optical microscopy using transmissive micro structures

以高分辨率检查物体细节对于许多研究、开发和制造领域至关重要。一个简单的选择是经典光学显微镜。这种方法的决议是，然而，由阿贝描述的决议限制的限制。因此，过去已经一次又一次地研究了克服这一限制的方法。提高分辨率的一种方法是在物体表面应用微球。可实现的分辨率主要取决于微球的直径和微球与周围介质之间的折射率差。在文献中，使用标准光学显微镜来分辨距离<100 nm的物体，对应的分辨率远小于波长。目前，还没有通用的模型来解释这种实验观察到的效应。然而，广泛的理解对于评估该方法的局限性和潜力以及优化所使用的微结构的成像特性是必不可少的。在文献中，实验数据仅限于球形微结构的研究，既不能显示无畸变的图像，也不能显示更大的视场。对偏离球形的微观结构的研究仅限于对其聚焦特性的模拟；没有实验结果。因此，建议的项目有两个目标：1。发展一个理论模型来解释分辨率低于阿贝衍射极限的影响（以下称为超分辨率）：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原理，特别是扩展的惠更斯-菲涅耳方法，以理解超分辨率的影响。本项目将采用这种方法，以一种简化的方式描述消失场与微观结构的耦合。上述程序可减少计算时间，并允许在成像特性方面对微结构进行迭代优化。2. 理论发现的实验实现：虽然迄今为止文献中只有球形结构进行了实验研究，非球面结构仅通过模拟来描述，但在我们的提议中，球体和自由形状微结构通过直接激光写入来制造，光学表征，并通过这种方式验证超分辨率的影响。因此，提出的项目使得有可能获得一个有充分根据的理论理解来解释超分辨率的影响。这也使激光直接刻写制备球面和非球面微结构的超分辨率光学光学显微镜具有了实际应用价值。

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.