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

白光干涉显微镜是一种成熟的表面微观结构三维测量方法，其高度分辨率在纳米范围内。虽然衍射限制了显微成像中的横向分辨率，但3D显微镜的横向分辨率没有普遍接受的定义。此外，即使结构是横向良好分辨的，在测量的和真实的微观结构之间也会出现系统性差异。在项目的第一阶段，研究了测量具有高横向分辨率的微米和亚微米结构的白光干涉仪的传递特性。仪器的修改以及修改后的信号处理算法进行了研究。对基于Linnik干涉仪的实验装置进行了扩展和优化。确定了几个技术改进的主题，即测得的高度分布对所用光的中心波长和偏振状态的依赖性，共焦和结构照明的引入，以及在测量干涉信号的相位评估的情况下测量结果对评估波长的依赖性。在项目的第二阶段，应系统地验证、概括和精确地延长期限。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摄像机。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，都将导致改进的干涉测量系统和策略，用于可靠地测量微米甚至亚微米结构。这些新系统的特点是更好的横向分辨率和显着较小的系统偏差相比，今天的仪器。

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.