Confocal Linnik white-light interferometer for micro- and nanostructure measurement with high lateral resolution

白光干涉显微镜被认为是一种成熟的表面微观结构三维测量方法，高度分辨率在纳米范围内。虽然衍射限制了显微成像的横向分辨率，但三维显微镜的横向分辨率没有一个普遍接受的定义。此外，即使结构横向很好地解决了测量和实际微观结构之间的系统差异。项目一期研究了高横向分辨率测量微米和亚微米结构的白光干涉仪的传输特性。研究了仪器改进和改进的信号处理算法。对基于林尼克干涉仪的实验布置进行了扩展和优化。确定了几个技术改进的主题，即测量的高度轮廓对中心波长和使用光的偏振状态的依赖，共聚焦和结构照明的引入，以及在测量干涉信号的相位评估情况下测量结果对评估波长的依赖。在项目的第二个阶段，对第一个阶段获得的知识进行系统的验证、概括和精确的扩展。为此，现有装置应配备一个中心波长可调的低相干光源模块和一个横向高分辨率低噪声相机。该项目旨在最大限度地减少被称为蝙蝠翼的系统测量伪影，并提高横向分辨率，甚至低于阿贝分辨率极限。无论是实验还是理论研究和模拟，都将导致改进干涉测量系统和策略，以可靠地测量微米甚至亚微米结构。与目前的仪器相比，这些新型系统具有更好的横向分辨率和更小的系统偏差。

White-light interference microscopy is known as a well-established method for three dimensional measurement of surface microstructure with height resolution in the nanometre range. Although diffraction limits the lateral resolution in microscopic imaging, no generally accepted definition of the lateral resolution of 3D microscopes exists. In addition, even if the structures are laterally well-resolved systematic discrepancies between measured and real microstructures occur. In the first period of the project the transfer characteristics of white-light interferometers measuring micrometer and sub-micrometer structures with high lateral resolution were studied. Instrumental modifications as well as modified signal processing algorithms were investigated. The experimental arrangement based on a Linnik interferometer was extended and optimized successively. Several topics of technological improvement were identified, namely the dependence of measured height profiles on the centre wavelength and the state of polarization of the used light, the introduction of confocal and structured illumination, as well as the dependence of the measurement results on the evaluation wavelength in case of phase evaluation of the measured interference signals.In the second period of the project the knowledge obtained in the first period shall be systematically validated, generalized, and precisely extended. For this purpose the existing setup shall be equipped with a low coherent light source module with adjustable centre wavelength and a laterally highly resolving low-noise camera. The project aims to minimize systematic measurement artifacts known as batwings and to improve the lateral resolution even below the Abbe resolution limit. Both, experimental as well as theoretical investigations and simulations shall result in improved interferometric measurement systems and strategies for reliable measurement of micrometer and even sub-micrometer structures. These novel systems are characterized by better lateral resolution and significantly smaller systematic deviations compared to todays instruments.