Recent Submissions
Nondestructive surface profiling of hidden MEMS using an infrared low-coherence interferometric microscope
(2018) Krauter, Johann; Osten, Wolfgang
There are a wide range of applications for micro-electro-mechanical systems (MEMS). The automotive and consumer market is the strongest driver for the growing MEMS industry. A 100 % test of MEMS is particularly necessary since these are often used for safety-related purposes such as the ESP (Electronic Stability Program) system. The production of MEMS is a fully automated process that generates 90 % of the costs during the packaging and dicing steps. Nowadays, an electrical test is carried out on each individual MEMS component before these steps. However, after encapsulation, MEMS are opaque to visible light and other defects cannot be detected. Therefore, we apply an infrared low-coherence interferometer for the topography measurement of those hidden structures. A lock-in algorithm-based method is shown to calculate the object height and to reduce ghost steps due to the 2π-unambiguity. Finally, measurements of different MEMS-based sensors are presented.
2D MoS2 nanopores : ionic current blockade height for clustering DNA events
(2019) Diaz Carral, Angel; Shekar Sarap, Chandra; Liu, Ke; Radenovic, Aleksandra; Fyta, Maria
2D nanopores can be used to electrophoretically drive DNA molecules, which can in turn be identified through measurable electronic current blockades. In this work, we use experimental data from molybdenum disulfide nanopores threading DNA nucleotides and propose a methodological approach to interpret DNA events. Specifically, the experimental ionic traces are used to train an unsupervised machine learning model for identifying distinct molecular events through the 2D nanopore. For the first time, we propose a clustering of experimental 2D nanopore data based on the ionic current blockade height and unrelated to the traditional dwell time for each DNA event. Within this approach, the blockade level information is implicitly included in the feature space analysis and does not need to be treated explicitly. We could show the higher efficiency of the blockade height over the traditional dwell time also in coping with sparse nanopore data sets. Our approach allows for a deep insight into characteristic molecular features in 2D nanopores and provides a feedback mechanism to tune these materials and interpret the measured signals. It has, thus, a high impact on the efficiency of 2D nanopore-based DNA sequencers.
Topologically protected edge states in small Rydberg systems
(2018) Weber, Sebastian; Léséleuc, Sylvain de; Lienhard, Vincent; Barredo, Daniel; Lahaye, Thierry; Browaeys, Antoine; Büchler, Hans Peter
We propose a simple setup of Rydberg atoms in a honeycomb lattice which gives rise to topologically protected edge states. The proposal is based on the combination of dipolar exchange interaction, which couples the internal angular momentum and the orbital degree of freedom of a Rydberg excitation, and a static magnetic field breaking time reversal symmetry. We demonstrate that for realistic experimental parameters, signatures of topologically protected edge states are present in small systems with as few as 10 atoms. Our analysis paves the way for the experimental realization of Rydberg systems characterized by a topological invariant, providing a promising setup for future application in quantum information.
Fibre based hyperentanglement generation for dense wavelength division multiplexing
(2019) Vergyris, Panagiotis; Mazeas, Florent; Gouzien, Elie; Labonté, Laurent; Alibart, Olivier; Tanzilli, Sébastien; Kaiser, Florian
Entanglement is a key resource in quantum information science and associated emerging technologies. Photonic systems offer a large range of exploitable entanglement degrees of freedom (DOF) such as frequency, time, polarization, and spatial modes. Hyperentangled photons exploit multiple DOF simultaneously to enhance the performance of quantum information protocols. Here, we report a fully guided-wave approach for generating polarization and energy-time hyperentangled photons at telecom wavelengths. Moreover, by demultiplexing the broadband emission spectrum of the source into five standard telecom channel pairs, we demonstrate compliance with fibre network standards and improve the effective bit rate capacity of the quantum channel up to one order of magnitude. In all channel pairs, we observe a violation of a generalised Bell inequality by more than 27 standard deviations, underlining the relevance of our approach.
Trajectories from standard to incremental and pioneering innovation in timber construction : multi-storey timber buildings in Germany, Austria, and Switzerland
(2025) Svatoš-Ražnjević, Hana; Boeva, Yana; Kropp, Cordula; Menges, Achim
Surface-modified gelatin hydrogel scaffolds with imprinted microgrooves : physical characterization and study on endothelial cell interaction
(2025) Salehi, Ali; Rutz, Lena; Ulbrich, Konstantin; Stevens, Johanna; Guttmann, Markus; Worgull, Matthias; Cattaneo, Giorgio
Explaining deviant voting in subnational elections : the case of local council elections in Germany
(2024) Graeb, Frederic; Vetter, Angelika
HyperLoop : hyperspectral assisted loop closure detection in 3DGS SLAM system for planetary exploration
(2025) Bhalla, Annie
Autonomous navigation of planetary rovers remains a major challenge in space exploration, especially in environments that are featureless, poorly illuminated, or obscured by dust. Recent progress in Simultaneous Localization and Mapping (SLAM) based on 3D Gaussian Splatting (3DGS) [1] has demonstrated the ability to generate dense and accurate 3D maps while preserving global consistency through loop closure. Such systems perform reliably in structured settings, where conventional loop closure detection methods - whether relying on handcrafted visual place recognition techniques such as Bag-of-Visual-Words with SIFT descriptors, or deep learning models trained on object-centric datasets - are effective at producing robust descriptors. However, in adverse planetary conditions these methods face significant limitations, often leading to degraded loop closure detection and increased localization drift.
To address these challenges, this research investigates the integration of hyperspectral imaging (HSD), particularly in the near-infrared range, into the loop closure module of 3DGS-based SLAM system-LoopSplat. Hyperspectral descriptors are extracted to capture material-level properties of the environment, thereby providing additional semantic information that complements RGB features and strengthens loop closure detection. Multiple descriptor extraction techniques for both RGB and HSI modalities are explored to evaluate their effectiveness in unstructured planetary-like environments.
The proposed framework is assessed on datasets collected at the Moon-Mars Outdoor Test Site (MMOTS) of the German Aerospace Center (DLR). Results demonstrate the feasibility of incorporating HSI into SLAM pipelines, showing improved loop closure reliability and localization accuracy in challenging conditions. Performance remains highly dependent on sensor’s spectral range and the ability to capture discriminative material cues.
Overall, this work highlights the potential of hyperspectral imaging to enhance SLAM for planetary exploration, offering a step toward more robust and reliable rover autonomy in unstructured extraterrestrial terrains.
Lebenszyklusanalyse des Wärmeträgermediums und der Rohrleitungen eines kalten Nahwärmenetzes
(2026) Huber, Peer; Fischer, Julian; Drück, Harald; Hafner, Bernd; Dott, Ralf
Inverse Verfahren zur flächenaufgelösten Wärmestromdichtemessung
(2026) Dürnhofer, Christian; Fasoulas, Stefanos (Prof. Dr.-Ing.)