Browsing by Author "Herkommer, Alois"

Now showing 1 - 18 of 18

Open Access
3D direct laser writing of highly absorptive photoresist for miniature optical apertures
(2022) Schmid, Michael D.; Toulouse, Andrea; Thiele, Simon; Mangold, Simon; Herkommer, Alois; Giessen, Harald
The importance of 3D direct laser writing as an enabling technology increased rapidly in recent years. Complex micro-optics and optical devices with various functionalities are now feasible. Different possibilities to increase the optical performance are demonstrated, for example, multi-lens objectives, a combination of different photoresists, or diffractive optical elements. It is still challenging to create fitting apertures for these micro optics. In this work, a novel and simple way to create 3D-printed opaque structures with a highly absorptive photoresist is introduced, which can be used to fabricate microscopic apertures increasing the contrast of 3D-printed micro optics and enabling new optical designs. Both hybrid printing by combining clear and opaque resists, as well as printing transparent optical elements and their surrounding opaque apertures solely from a single black resist by using different printing thicknesses are demonstrated.
Open Access
3D printed micro-optics for quantum technology: Optimised coupling of single quantum dot emission into a single-mode fibre
(2021) Sartison, Marc; Weber, Ksenia; Thiele, Simon; Bremer, Lucas; Fischbach, Sarah; Herzog, Thomas; Kolatschek, Sascha; Jetter, Michael; Reitzenstein, Stephan; Herkommer, Alois; Michler, Peter; Portalupi, Simone Luca; Giessen, Harald
Open Access
3D printed stacked diffractive microlenses
(2019) Thiele, Simon; Pruss, Christof; Herkommer, Alois; Giessen, Harald
Open Access
3D printing of colored micro-optics
(2023) Aslani, Valese; Toulouse, Andrea; Schmid, Michael; Giessen, Harald; Haist, Tobias; Herkommer, Alois
Open Access
3D-printed miniature spectrometer for the visible range with a 100 × 100 μm2 footprint
(2021) Toulouse, Andrea; Drozella, Johannes; Thiele, Simon; Giessen, Harald; Herkommer, Alois
Open Access
Data-driven development of sparse multi-spectral sensors for urological tissue differentiation
(2023) Fischer, Felix; Frenner, Karsten; Granai, Massimo; Fend, Falko; Herkommer, Alois
Open Access
Data-driven identification of biomarkers for in situ monitoring of drug treatment in bladder cancer organoids
(2022) Becker, Lucas; Fischer, Felix; Fleck, Julia L.; Harland, Niklas; Herkommer, Alois; Stenzl, Arnulf; Aicher, Wilhelm K.; Schenke-Layland, Katja; Marzi, Julia
Three-dimensional (3D) organoid culture recapitulating patient-specific histopathological and molecular diversity offers great promise for precision medicine in cancer. In this study, we established label-free imaging procedures, including Raman microspectroscopy (RMS) and fluorescence lifetime imaging microscopy (FLIM), for in situ cellular analysis and metabolic monitoring of drug treatment efficacy. Primary tumor and urine specimens were utilized to generate bladder cancer organoids, which were further treated with various concentrations of pharmaceutical agents relevant for the treatment of bladder cancer (i.e., cisplatin, venetoclax). Direct cellular response upon drug treatment was monitored by RMS. Raman spectra of treated and untreated bladder cancer organoids were compared using multivariate data analysis to monitor the impact of drugs on subcellular structures such as nuclei and mitochondria based on shifts and intensity changes of specific molecular vibrations. The effects of different drugs on cell metabolism were assessed by the local autofluorophore environment of NADH and FAD, determined by multiexponential fitting of lifetime decays. Data-driven neural network and data validation analyses (k-means clustering) were performed to retrieve additional and non-biased biomarkers for the classification of drug-specific responsiveness. Together, FLIM and RMS allowed for non-invasive and molecular-sensitive monitoring of tumor-drug interactions, providing the potential to determine and optimize patient-specific treatment efficacy.
Open Access
Design and realization of a miniaturized high resolution computed tomography imaging spectrometer
(2023) Amann, Simon; Haist, Tobias; Gatto, Alexander; Kamm, Markus; Herkommer, Alois
Open Access
Distortion-free multi-element Hypergon wide-angle micro-objective by femtosecond 3D printing
(2020) Weber, Ksenia; Wang, Zhen; Thiele, Simon; Herkommer, Alois; Giessen, Harald
Open Access
Fast bidirectional vector wave propagation method showcased on targeted noise reduction in imaging fiber bundles using 3D-printed micro optics
(2023) Wende, Marco; Drozella, Johannes; Herkommer, Alois
Open Access
FeaSel-Net : a recursive feature selection callback in neural networks
(2022) Fischer, Felix; Birk, Alexander; Somers, Peter; Frenner, Karsten; Tarín, Cristina; Herkommer, Alois
Selecting only the relevant subsets from all gathered data has never been as challenging as it is in these times of big data and sensor fusion. Multiple complementary methods have emerged for the observation of similar phenomena; oftentimes, many of these techniques are superimposed in order to make the best possible decisions. A pathologist, for example, uses microscopic and spectroscopic techniques to discriminate between healthy and cancerous tissue. Especially in the field of spectroscopy in medicine, an immense number of frequencies are recorded and appropriately sized datasets are rarely acquired due to the time-intensive measurements and the lack of patients. In order to cope with the curse of dimensionality in machine learning, it is necessary to reduce the overhead from irrelevant or redundant features. In this article, we propose a feature selection callback algorithm (FeaSel-Net) that can be embedded in deep neural networks. It recursively prunes the input nodes after the optimizer in the neural network achieves satisfying results. We demonstrate the performance of the feature selection algorithm on different publicly available datasets and compare it to existing feature selection methods. Our algorithm combines the advantages of neural networks’ nonlinear learning ability and the embedding of the feature selection algorithm into the actual classifier optimization.
Open Access
Improvement in systematic error in background-oriented schlieren results by using dynamic backgrounds
(2021) Reichenzer, Frieder; Schneider, Mike; Herkommer, Alois
The use of electronic visual displays for background-oriented schlieren allows for the quick change of the reference images. In this study, we show that the quality of synthetic and background-oriented schlieren images can be improved by acquiring a set of images with different reference images and generating a median displacement field from it. To explore potential benefits, we studied different background changing strategies and their effect on the quality of the evaluation of the displacement field via artificial and experimental image distortions.
Open Access
Injection molding of encapsulated diffractive optical elements
(2023) Wagner, Stefan; Treptow, Kevin; Weser, Sascha; Drexler, Marc; Sahakalkan, Serhat; Eberhardt, Wolfgang; Guenther, Thomas; Pruss, Christof; Herkommer, Alois; Zimmermann, André
Microstructuring techniques, such as laser direct writing, enable the integration of microstructures into conventional polymer lens systems and may be used to generate advanced functionality. Hybrid polymer lenses combining multiple functions such as diffraction and refraction in a single component become possible. In this paper, a process chain to enable encapsulated and aligned optical systems with advanced functionality in a cost-efficient way is presented. Within a surface diameter of 30 mm, diffractive optical microstructures are integrated in an optical system based on two conventional polymer lenses. To ensure precise alignment between the lens surfaces and the microstructure, resist-coated ultra-precision-turned brass substrates are structured via laser direct writing, and the resulting master structures with a height of less than 0.002 mm are replicated into metallic nickel plates via electroforming. The functionality of the lens system is demonstrated through the production of a zero refractive element. This approach provides a cost-efficient and highly accurate method for producing complicated optical systems with integrated alignment and advanced functionality.
Open Access
Mass-producible micro-optical elements by injection compression molding and focused ion beam structured titanium molding tools
(2020) Ristok, Simon; Roeder, Marcel; Thiele, Simon; Hentschel, Mario; Guenther, Thomas; Zimmermann, André; Herkommer, Alois; Giessen, Harald
Open Access
Numerical analysis of micro-optics based single photon sources via a combined physical optics and rigorous simulations approach
(2023) Jimenez, Carlos; Hellmann, Christian; Toulouse, Andrea; Drozella, Johannes; Wyrowski, Frank; Herkommer, Alois
Open Access
Stitching-free 3D printing of millimeter-sized highly transparent spherical and aspherical optical components
(2020) Ristok, Simon; Thiele, Simon; Toulouse, Andrea; Herkommer, Alois; Giessen, Harald
Open Access
Tailored nanocomposites for 3D printed micro-optics
(2020) Weber, Ksenia; Werdehausen, Daniel; König, Peter; Thiele, Simon; Schmid, Michael; Decker, Manuel; Oliveira, Peter William de; Herkommer, Alois; Giessen, Harald
Open Access
Ultrathin monolithic 3D printed optical coherence tomography endoscopy for preclinical and clinical use
(2020) Li, Jiawen; Thiele, Simon; Quirk, Bryden C.; Kirk, Rodney W.; Verjans, Johan W.; Akers, Emma; Bursill, Christina A.; Nicholls, Stephen J.; Herkommer, Alois; Giessen, Harald; McLaughlin, Robert A.