More Like this

1. Connected-tube MPP Model for unsupervised 3D fiber detection

   https://doi.org/10.2352/ISSN.2470-1173.2020.14.COIMG-305  

   Li, Tianyu; Aguilar, Camilo G.; Agyei, Ronald F.; Hanhan, Imad A.; Sangid, Michael D.; Comer, Mary L. (January 2020, Electronic Imaging)

   Fast track article for IS&T International Symposium on Electronic Imaging 2020: Computational Imaging proceedings. 

   more » « less
2. Two-photon, fiber-coupled, super-resolution microscope for biological imaging

   https://doi.org/10.1063/5.0075012  

   Heffernan, Brendan M.; Riley, Peter S.; Supekar, Omkar D.; Meyer, Stephanie A.; Restrepo, Diego; Siemens, Mark E.; Gibson, Emily A.; Gopinath, Juliet T. (March 2022, APL Photonics)

   Imaging sub-diffraction dynamics of neural nanostructures involved in behaviors such as learning and memory in a freely moving animal is not possible with existing techniques. Here, we present a solution in the form of a two-photon (2P), fiber-coupled, stimulated emission depletion microscope and demonstrate its capabilities by acquiring super-resolution imaging of mammalian cells. A polarization-maintaining fiber is used to transport both the 2P excitation light (915 nm) and the donut-shaped depletion beam (592 nm), which is constructed by adding two temporally incoherent and orthogonally polarized Hermite–Gaussian fiber modes. The fiber output is insensitive to bending or temperature changes and is the first demonstration toward deep tissue super-resolution imaging in awake behaving animals. 

   more » « less
3. Polarization-resolved second-harmonic generation imaging through a multimode fiber

   https://doi.org/10.1364/OPTICA.430295  

   Cifuentes, Angel; Pikálek, Tomáš; Ondráčková, Petra; Amezcua-Correa, Rodrigo; Antonio-Lopez, José_Enrique; Čižmár, Tomáš; Trägårdh, Johanna (August 2021, Optica)

   Multimode fiber-based endoscopes have recently emerged as a tool for minimally invasive endoscopy in tissue, at depths well beyond the reach of multiphoton imaging. Here, we demonstrate label-free second-harmonic generation (SHG) microscopy through such a fiber endoscope. We simultaneously fully control the excitation polarization state and the spatial distribution of the light at the fiber tip, and we use this to implement polarization-resolved SHG imaging, which allows imaging and identification of structural proteins such as collagen and myosin. We image mouse tail tendon and heart tissue, employing the endoscope at depths up to 1 mm, demonstrating that we can differentiate these structural proteins. This method has the potential for enabling instant andin situdiagnosis of tumors and fibrotic conditions in sensitive tissue with minimal damage. 

   more » « less
4. Depixelation and enhancement of fiber bundle images by bundle rotation

   https://doi.org/10.1364/AO.59.000536  

   Renteria, Carlos; Suárez, Javier; Licudine, Alyssa; Boppart, Stephen_A (January 2020, Applied Optics)

   Fiber bundles have become widely adopted for use in endoscopy, live-organism imaging, and other imaging applications. An inherent consequence of imaging with these bundles is the introduction of a honeycomb-like artifact that arises from the inter-fiber spacing, which obscures features of objects in the image. This artifact subsequently limits applicability and can make interpretation of the image-based data difficult. This work presents a method to reduce this artifact by on-axis rotation of the fiber bundle. Fiber bundle images were first low-pass and median filtered to improve image quality. Consecutive filtered images with rotated samples were then co-registered and averaged to generate a final, reconstructed image. The results demonstrate removal of the artifacts, in addition to increased signal contrast and signal-to-noise ratio. This approach combines digital filtering and spatial resampling to reconstruct higher-quality images, enhancing the utility of images acquired using fiber bundles. 

   more » « less
5. Inverse-designed large field-of-view polychromatic metalens for tri-color scanning fiber endoscopy

   https://doi.org/10.1038/s44172-025-00377-7  

   Xie, Ningzhi; Zhou, Zhihao; Fröch, Johannes_E; Carson, Matthew_D; Majumdar, Arka; Seibel, Eric_J; Böhringer, Karl_F (March 2025, Communications Engineering)

   Abstract Metalenses, with their ultrathin thicknesses and their ease for achieving ultra small diameters, offer a promising alternative to refractive lenses in miniaturized imaging systems, such as endoscopes, potentially enabling applications in tightly confined spaces. However, traditional metalenses suffer from strong chromatic aberrations, limiting their utility in multi-color imaging. To address this limitation, here we present an inverse-designed polychromatic metalens with a diameter of 680 μm, focal length of 400 μm, and low dispersion across 3 distinct wavelengths at 643 nm, 532 nm, and 444 nm. The metalens collimates and steers light emitted from a scanning fiber tip, generating scanning beams across a 70° field-of-view to provide illumination for a scan-based imaging. The metalens provides a close-to-diffraction-limited 0.5° angular resolution, only restricted by the effective aperture of the system. The average relative efficiency among three design wavelengths is around 32% for on-axis angle and 13% averaged across the entire field-of-view. This work holds promise for the application of metalenses in endoscopes and other miniaturized imaging systems. 

   more » « less