Extreme ultraviolet ptychography of young mouse neurons

Abstract

Ptychography is a lensless, phase-sensitive, diffraction-imaging technique that can provide high-resolution images of non-crystalline objects. Iterative phase-retrieval algorithms replace the role of lenses, allowing reconstruction of the object image. The lensless nature of ptychography provides a major advantage for use with extreme ultraviolet and soft x-ray wavelengths, which are an important spectral region for high-resolution microscopy but difficult to manipulate with lenses. In this project, 7DIV (days in vitro) mouse hippocampal neurons are imaged for the first time using EUV ptychography at the University of Southampton and on the Artemis laser at the Central Laser Facility (Didcot, UK) at a wavelength of 29 nm. The EUV radiation is generated via high harmonic generation through argon gas. The images show fine structures that are well defined and not resolved via  conventional microscopy, achieving up to 102 nm resolution over a 42 μm field of view in both phase and amplitude. The ptychography imaging experiment is  also carried out using a projected pinhole in place of a physical pinhole, resulting  in successful, albeit poorer reconstruction. Compositional analysis on the  reconstructed images is also explored, by considering the complex refractive index, n = 1 - δ + iβ . The ratio δ/β which is unique for different materials, can be calculated from the image data, and can provide some insight on spatial distribution of content across a structural feature.

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Identifiers

ORCID for Jeremy G. Frey: orcid.org/0000-0003-0842-4302

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