A Super-Condenser for Labelfree Nanoscopy [article]

Florian Ströhl, Ida S. Opstad, Jean-Claude Tinguely, Firehun T. Dullo, Ioanna Mela, Johannes W.M. Osterrieth, Balpreet S. Ahluwalia, Clemens F. Kaminski
2019 arXiv   pre-print
Labelfree nanoscopy encompasses optical imaging with resolution in the 100 nm range using visible wavelengths. Here, we present a labelfree nanoscopy method that combines Fourier ptychography with waveguide microscopy to realize a 'super-condenser' featuring maximally inclined coherent darkfield illumination with artificially stretched wave vectors due to large refractive indices of the employed Si_3N_4 waveguide material. We produce the required coherent plane wave illumination for Fourier
more » ... hography over imaging areas 400 μm^2 in size via adiabatically tapered single-mode waveguides and tackle the overlap constraints of the Fourier ptychography phase retrieval algorithm two-fold: firstly, the directionality of the illumination wave vector is changed sequentially via a multiplexed input structure of the waveguide chip layout and secondly, the wave vector modulus is shortend via step-wise increases of the illumination light wavelength over the visible spectrum. We validate the method via in silico and in vitro experiments and provide details on the underlying image formation theory as well as the reconstruction algorithm.
arXiv:1905.02401v1 fatcat:mtgwqako4zavreopgovsypct54