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• Sommernes, Jon-Richard; Thiyagarajan, Dhivya Borra & Ströhl, Florian (2025). Rapid and gentle volumetric imaging of host–pathogen interactions in salmon skin cells using projective oblique plane microscopy. Scientific Reports. 15(1). doi: 10.1038/s41598-025-33371-2. Full text in Research Archive
• Sommernes, Jon-Richard; Millett-Sikking, Alfred & Ströhl, Florian (2024). S-polarized light-sheets improve resolution and light-efficiency in oblique plane microscopy. Scientific Reports. 14(1). doi: 10.1038/s41598-024-53900-9. Full text in Research Archive Show summary

  Oblique plane microscopy (OPM) offers 3D optically sectioned imaging with high spatial- and temporal-resolution while enabling conventional sample mounting. The technique uses a concatenation of three microscopes, two for remote focusing and a tilted tertiary microscope, often including an immersion objective, to image an oblique sample plane. This design induces Fresnel reflections and a reduced effective aperture, thus impacting the resolution and light efficiency of the system. Using vectorial diffraction simulations, the system performance was characterized based on illumination angle and polarization, signal to noise ratio, and refractive index of the tertiary objective immersion. We show that for samples with high fuorescent anisotropy, s-polarized light-sheets yield higher average resolution for all system configurations, as well as higher light-efficiency. We also provide a tool for performance characterization of arbitrary light-sheet imaging systems.

• Davis, Samuel; Sommernes, Jon-Richard; hambura, sebastian; Riedel, Levin; Gil, Alejandro & Ikmi, Aissam [Show all 8 contributors for this article] (2024). Mesoscopic axially swept oblique plane microscope for the imaging of freely moving organisms with near-isotropic resolution. Biomedical Optics Express. 15(12), p. 6715–6724. doi: 10.1364/BOE.537262. Full text in Research Archive Show summary

  Rapid three-dimensional imaging over extended fields of views (FOVs) is crucial to the study of organism-wide systems and biological processes in vivo. Selective-plane illumination microscopy (SPIM) is a powerful method for high spatio-temporal resolution in toto imaging of such biological specimens. However, typical SPIM implementations preclude conventional sample mounting and have anisotropic imaging performance, in particular when designed for large FOVs over 1 mm diameter. Here, we introduce axial sweeping of the illumination into a non-orthogonal dual-objective oblique plane microscope (OPM) design, thereby enabling the observation of freely moving animals over millimeter sized FOVs, at close to isotropic, sub-cellular resolution. We apply our mesoscopic axially swept OPM (MASOPM) to imaging the behavioral dynamics of the sea anemone Nematostella vectensis over 1 × 0.7 × 0.4 mm at 1.7 × 2.6 × 3.7 µm resolution and 0.5 Hz volume rate.

• Reischke, Marie; Vanderpoorten, Oliver & Ströhl, Florian (2023). Rapid prototyping of 1xN multifocus gratings via additive direct laser writing. Micro and Nano Engineering (MNE). 19. doi: 10.1016/j.mne.2023.100186. Full text in Research Archive Show summary

  Multifocus gratings (MFGs) enable microscopes and other imaging systems to record entire Z-stacks of images in a single camera exposure. The exact grating shape depends on microscope parameters like wavelength and magnification and defines the multiplexing onto a grid of MxN Z-slices. To facilitate the swift production and alteration of MFGs for a system and application at hand, we have developed a fabrication protocol that allows manufacturing of 1xN MFGs within hours and without the requirement of clean room facilities or hazardous etching steps. Our approach uses photolithography with a custom-built stage-scanning direct laser writing (DLW) system. By writing MFG grating lines into spin-coated negative tone SU-8 photoresist, polymerized parts are crafted onto the substrate and thus directly become a part of the grating structure. We provide software to generate the required MFG grating line paths, details of the DLW system and fully characterize a manufactured MFG. Our produced MFG is 5.4 mm in diameter and manages to record an image volume with a Z-span of over 600 μm without spherical aberrations or noticeable loss of resolution.

• Ströhl, Florian (2023). Instant Volume Microscopy of Organoids with SOLIS. Microscopy Today. ISSN 1551-9295. 31(5), p. 23–26. doi: 10.1093/mictod/qaad064. Full text in Research Archive Show summary

  Advancements in microscopy techniques have revolutionized our ability to explore the intricacies of biological systems, with engineered human heart tissue (EHT) being a particularly challenging target. In this article, we will have an in-depth look at the award-winning SOLIS technique (scanned oblique light-sheet instant-volume sectioning), a new twist on multifocus fluorescence microscopy. Through its unique capabilities, SOLIS offers a new approach on organoid and tissue imaging, providing unprecedented insights into the cellular architecture of these complex artificial samples. By being able to record optically sectioned volumes during single camera exposures, SOLIS demonstrates remarkable advantages over traditional multifocus microscopy, underscoring its potential to transform our understanding of developmental biology, disease mechanisms, and potential therapeutic interventions.

• Ströhl, Florian; Bruggeman, Ezra; Rowlands, Christopher; Wolfson, Deanna & Ahluwalia, Balpreet Singh (2022). Quantification of the NA dependent change of shape in the image formation of a z-polarised fluorescent molecule using vectorial diffraction simulations. Microscopy research and technique (Print). ISSN 1059-910X. 85(5), p. 2016–2022. doi: 10.1002/jemt.24060. Full text in Research Archive Show summary

  Vectorial diffraction simulations show that the PSF of a z-polarised emitter changes shape above a 0.7 NA of the image-forming lens and can thus impact novel microscopy techniques like OPM in single molecule studies.

• Ströhl, Florian; Hansen, Daniel Henry; Grifo, Mireia Nager & Birgisdottir, Åsa Birna (2022). Multifocus microscopy with optically sectioned axial superresolution. arXiv.org. ISSN 2331-8422. doi: 10.48550/arXiv.2206.01257. Full text in Research Archive Show summary

  Multifocus microscopy enables recording of entire volumes in a single camera exposure. In dense samples, multifocus microscopy is severely hampered by background haze. Here, we introduce a scalable multifocus method that incorporates optical sectioning and offers axial superresolution capabilities. In our method, a dithered oblique light-sheet scans the sample volume during a single exposure, while generated fluorescence is linearised onto the camera with a multifocus optical element. A synchronised rolling shutter readout realised optical sectioning. We describe the technique theoretically and verify its optical sectioning and superresolution capabilities. We demonstrate a prototype system with a multifocus beam splitter cascade and record monolayers of endothelial cells at 35 volumes per second. We furthermore image uncleared engineered human heart tissue and visualise the distribution of mitochondria at axial superresolution. Our method manages to capture sub-diffraction sized mitochondria-derived vesicles up to 30 um deep into the tissue.

• Ströhl, Florian; Hansen, Daniel Henry; Grifo, Mireia Nager & Birgisdottir, Åsa birna (2022). Multifocus microscopy with optical sectioning and high axial resolution. Optica. 9(11), p. 1210–1218. doi: 10.1364/OPTICA.468583. Full text in Research Archive Show summary

  Multifocus microscopy enables recording of entire volumes in a single camera 11 exposure. In dense samples, multifocus microscopy is severely hampered by background haze. 12 Here, we introduce a scalable multifocus method that incorporates optical sectioning and offers 13 improved axial resolution capabilities. In our method, a dithered oblique light-sheet scans the 14 sample volume during a single exposure, while fluorescence from each illuminated plane in the 15 sample is mapped onto a line on the camera with a multifocus optical element. A synchronized 16 rolling shutter readout realizes optical sectioning. We describe the technique theoretically and 17 verify its optical sectioning and resolution improvement capabilities. We demonstrate a 18 prototype system with a multifocus beam splitter cascade and record monolayers of endothelial 19 cells at 35 volumes per second. We furthermore image uncleared engineered human heart tissue 20 and visualize the distribution of mitochondria at high axial resolution. Our method manages to 21 capture sub-diffraction sized mitochondria-derived vesicles up to 30 µm deep into the tissue.

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• Sommernes, Jon-Richard & Ströhl, Florian (2024). S-polarized light-sheets improve resolution and light efficiency in Oblique Plane Microscopy. Full text in Research Archive
• Ströhl, Florian (2024). Brillouin Microscopy Development at the Arctic University of Norway. Full text in Research Archive
• Ströhl, Florian (2024). The basics of optical alignment. Imaging and Microscopy. ISSN 2160-8881. Full text in Research Archive Show summary

  Precise optical alignment is critical for high-quality microscopy imaging, especially in custom-built systems. This guide details essential alignment steps, from beam path setup to lens collimation and centering, introduces key tools like pinholes and shearing interferometers, and advocates for a modular construction approach. This article aims to empower microscopy enthusiasts with practical alignment techniques and encourages ongoing learning and knowledge-sharing via an easy-access online resource on YouTube.

• Ströhl, Florian (2023). 3D+time microscopy of organoids:​ challenges and solutions​. Full text in Research Archive
• Ströhl, Florian (2023). Multifocus Microscopy with Optical Sectioning. Full text in Research Archive
• Ströhl, Florian (2023). New Methods for 3D Microscopy. Full text in Research Archive
• Ströhl, Florian (2023). 3D+time microscopy of organoids: challenges and solutions. Full text in Research Archive
• Ströhl, Florian (2022). Technology development for 4D microscopy. Full text in Research Archive
• Sommernes, Jon-Richard & Ströhl, Florian (2022). 3D vectorial diffraction simulations of oblique plane microscopy systems with solid immersion tertiary objectives. Full text in Research Archive
• Sommernes, Jon-Richard (2022). 3D vectorial diffraction simulations of oblique plane microscopy systems with solid immersion tertiary objectives. Full text in Research Archive
• Tomas, Rolland & Ströhl, Florian (2022). Han bygger neste generasjons mikroskop. [Internet]. Forskning.no. Full text in Research Archive
• Ströhl, Florian (2022). Instant Volume Microscopy. Full text in Research Archive
• Ströhl, Florian; Hansen, Daniel Henry; Sommernes, Jon-Richard; Reischke, Marie; Nàger, Mireia & Birgisdottir, Åsa birna (2022). Instant Volume Microscopy. Full text in Research Archive
• Ströhl, Florian (2022). 3D&UV – exploring new concepts in advanced imaging. Full text in Research Archive
• Ströhl, Florian (2022). Optically sectioned multi-focus microscopy. Full text in Research Archive
• Ströhl, Florian (2022). 3D microscopy development at the Arctic University. Full text in Research Archive
• Ströhl, Florian (2021). Optical transfer functions in inverted high-resolution light-sheet microscopy. Full text in Research Archive

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