arXiv subjects

Jens Wenzel Andreasen

Publications and source records attributed to Jens Wenzel Andreasen.

4 recordsLinked to original sources

arXiv2026

FaCT-GS: Fast and Scalable CT Reconstruction with Gaussian Splatting

Gaussian Splatting (GS) has emerged as a dominating technique for image rendering and has quickly been adapted for the X-ray Computed Tomography (CT) reconstruction task. However, despite its growing popularity, the benefits of GS are typically not substantial enough to motivate a transition from well-established reconstruction algorithms. This paper addresses the most significant remaining limitations of the GS-based approach by introducing FaCT-GS, a framework for fast and flexible CT reconstruction. Enabled by an in-depth optimization of the voxelization and rasterization pipelines, our new method is significantly faster than its predecessors and scales well with projection and output volume size. Furthermore, the improved voxelization enables rapid fitting of Gaussians to pre-existing volumes, which can serve as a prior for warm-starting the reconstruction, or simply as an alternative, compressed representation. FaCT-GS is over 4X faster than the State of the Art GS CT reconstruction on standard 512x512 projections, and over 13X faster on 2k projections. Implementation and data available through: https://github.com/PaPieta/fact-gs.

cs.CV↗

arXiv2026

Hyperspectral imaging for inline quality monitoring of roll-to-roll slot-die coated organic photovoltaic active layers

Lab-scale organic solar cells have shown high efficiency and strong potential for large-scale production. Among the fabrication techniques for upscaling production, roll-to-roll slot-die coating offers a cost-effective route toward scalable manufacturing. However, reliable in-line metrology is needed for real-time assessment and quality control of the coating during roll-to-roll manufacturing. In this work, we employ a hyperspectral camera for inline monitoring of P3HT and OIDTBR active layers in a roll-to-roll setup. Using multivariate curve resolution, we reliably resolved the spatial distribution of donor and acceptor contributions in the coating. Furthermore, by fitting the absorbance spectra of P3HT, we map the exciton bandwidth, providing insights into the polymer's aggregation and chain interactions. These results demonstrate the potential of hyperspectral imaging as a powerful tool for real-time monitoring and quality control in large-scale organic solar cell production.

physics.optics↗

arXiv2022

Manipulating organic semiconductor morphology with visible light

We present a method to manipulate the final morphology of roll-to-roll slot-die coated poly(3-hexylthiophene) (P3HT) by optically exciting the p-type polymer in solution while coating. Our results provide a comprehensive picture of the entire knowledge chain, from demonstrating how to apply our method to a fundamental understanding of the changes in morphology and physical properties induced by exciting P3HT while coating. By combining results from density functional theory and molecular dynamics simulations with a variety of X-ray experiments, absorption spectroscopy, and THz spectroscopy, we demonstrate the relationship between morphology and physical properties of the thin film. Specifically, in P3HT films excited with light during deposition, we observe changes in crystallinity and texture with more face-on orientation and increased out-of-plane charge mobility.

cond-mat.mtrl-sci↗

arXiv2019

Stable, carbon-free inks of Cu2ZnSnS4 nanoparticles synthesized at room temperature designed for roll-to-roll fabrication of solar cell absorber layers

We report on a novel room temperature approach for the synthesis of environmentally-friendly copper zinc tin sulfide ($Cu_2ZnSnS_4$) nanoparticles. The method is shown to be compositionally robust and able to produce $S^{2-}$-stabilized carbon-free nanoparticle inks that are suitable for an absorber layer in solar cells. No organic residues from the process were detected. The metal-composition and the occurrence of secondary phases is here correlated with synthesis conditions: By utilizing a reactant concentration of Cu/Sn < 1.8 and Sn(II) as tin-source it is possible to avoid the formation of $Cu_xS$-phases, which are detrimental for the solar cell performance when present in the final absorber layer. With nanoparticle sizes approaching the Bohr radius for $Cu_2ZnSnS_4$, the band gap can be broadened up to 1.7 eV. In addition, the conditions for forming stable, carbon-free aqueous inks of such $Cu_2ZnSnS_4$ nanoparticles are investigated and the stabilizing $NH_4^+/S^{2-}$-ion concentration affects the quality of the deposited absorber layer. The use of room temperature synthesis and stable aqueous ink formulations make the method suitable for roll-to-roll fabrication and upscaling.

cond-mat.mtrl-sci↗