188宝金博页面版

Lensless magneto-optical imagingV. Neu 1? , G. Pedrini 2 , I. Soldatov 1 , S. Reichelt 2 & R. Schäfer 1,3Magneto-optical methods, which utilize the interaction of polarized light with the magnetization of the sample in ref l ection through the magneto-optical Kerr ef f ect or in transmission through the accordant Faraday ef f ect, present prominent and widespread optical microscopy techniques for studying magnetic microstructures. In non-magnetic light microscopy, several alternatives to lens-based imaging have been developed, which of f er various advantages, including an improved ratio of fi eld-of-view to magnif i cation. Selected lensless methods also provide access to both intensity and phase information of the probing light fi eld, which presents an additional information channel obtainable from the studied sample. In a proof-of-principle study we verify that the reconstructed magneto-optical intensity obtained from a lensless multiplane recording scheme is in full qualitative agreement with conventional lens-based Faraday microscopy. The additional phase information, not accessible with conventional methods, of f ers direct access to domain information through the imaginary part of the Faraday or Kerr component in the studied material and allows domain imaging even in a crossed analyzer position or without the use of an analyzer. These fi ndings will open the path to exploit the various established advantages of lensless microscopy for the magneto-optical investigation of magnetic materials.Resolving magnetic microstructures by magnetic imaging techniques is the key to understanding of both fundamental magnetic phenomena and global magnetic behavior. It allows bridging the internal atomistic order of ferri-or ferromagnetic states and the fi nal functionality of a magnetic material or device on a mesoscopic scale 1,2 . Advanced imaging techniques exist for resolving magnetic microstructures at various length scales, from highly resolving XMCD (X-ray Magnetic Circular Dichroism), Lorentz-type TEM (Transmission Electron Microscopy) or sp-STM (spin-polarized Scanning Tunneling Microscopy) on the sub-10 nm scale to secondary or backscattering electron contrast on the millimeter scale 2 . Magneto-optical methods, which utilize the interaction of polarized light with the magnetization state of the sample in ref l ection through the magneto-optical Kerr ef f ect (MOKE) or in transmission through the accordant Faraday ef f ect present the most prominent and widespread techniques on an intermediate length scale. Kerr and Faraday microscopy can operate in a wide range of conditions (from cryogenic to high temperature, at variable fi eld strengths, in static, dynamic or stroboscopic fashion) and of f er resolution down to a few hundred nanometers, depending on the numerical aperture (NA) of the objective lens and the wavelength of the light 3 . For a recent review on magneto-optical microscopy see 4 . As the size of the lens is typically limited, the fi eld of view (FoV) reduces with high magnif i cation to typically some tens of micrometers.In non-magnetic light microscopy, several alternatives to lens-based imaging have been developed in the past. Some of them provide access to both intensity and phase information of the ref l ected or transmitted light wave that can be used for phase imaging and focusing. Th ere are also lensless techniques that of f er advantages in terms of the ratio of FoV and magnif i cation 5 . With special phase-retrieval techniques, wave-based imaging is possible without lenses, which fi rst of all removes the need of an additional optical component and furthermore extends the use of light-based imaging techniques to wavelengths, for which classical lenses are no longer available (deep UV, EUV, X-ray) 6 . Th e most direct phase retrieval method for a light-wave interacting with a sample is holography, which utilizes the interference of the sensing wave-front with a reference beam 7 . Holography allows encoding amplitude and phase information in an interference pattern. With the advance of digital detectors and computing technology, it was possible to record the holograms digitally and process them af t erwards 8,9 , which enables direct access to the quantitative phase information. Th is method, however, of t en implies severe geometrical restrictions. Other methods do work without a reference beam, and are based on an oversampling or redundancy of data and a subsequent numerical algorithm which determines a self-consistent set of amplitude and phase 10,11 of both the measured sample and the applied probe, i.e. the plane wave used for illumination. Examples are ptychographic methods 12,13 , which record multiple dif f raction images in a fi xed plane behind (in case of transmission) or in front (in case of ref l ection) of the sample with mutual overlap for the required redundancy, or (single pattern) coherent dif f raction imaging, which relies on a reference region, typically the known support of the sample 14 . Another, more simple scheme is based on a multiplane recording at various 1 Leibniz Institute for Solid State and Materials Research Dresden, 01099 Dresden, Germany. 2 Institute of Applied Optics (ITO), University of Stuttgart, 70569 Stuttgart, Germany. 3 Institute of Materials Science, Dresden University of Technology, 01062 Dresden, Germany. ? email: v.neu@ifw-dresden.deOPENScientif i c Reports | (2025) 15:28277 1 | https://doi.org/10.1038/s41598-025-10005-1www.nature.com/scientificreports