Development and optimization of a “water window” microscope based on a gas-puff target laser-produced plasma source

Alfio Torrisi,Andrzej Bartnik,Tomasz Fok,Łukasz Węgrzyński,Przemyslaw Wachulak,Henryk Fiedorowicz,L Torrisi,M Cutroneo

doi:10.1051/epjconf/201816703002

Alfio Torrisi, Andrzej Bartnik + Show 6 more

Open Access

https://doi.org/10.1051/epjconf/201816703002

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Abstract

A laser-plasma double stream gas-puff target source coupled with Fresnel zone plate (FZP) optics, operating at He-like nitrogen spectral line λ=2.88nm, is capable of acquire complementary information in respect to optical and electron microscopy, allowing to obtain high resolution imaging, compared to the traditional visible light microscopes, with an exposition time of a few seconds. The compact size and versatility of the microscope offers the possibility to perform imaging experiments in the university laboratories, previously restricted to large-scale photon facilities. Source and microscope optimization, and examples of applications will be presented and discussed.

Highlights

Since the ‘90s, significant efforts were made to bring technical capabilities of synchrotron-based microscopes to the development of compact sources [1]–[8], because that the small size and versatility of compact microscopy system offers the possibility to perform imaging experiments, previously restricted to large-scale facilities, in university laboratories
The N2 measured spectrum was quasimonochromatic, consisting of N5+:1s2-1s2p He-like nitrogen line at λ = 2.88 nm and N6+:1s-2p H-like nitrogen line at λ = 2.48 nm, according to L-α Ti edge at λ ~ 2.7 nm allows to filter out H-like line almost completely; most energy of the beam illuminating the sample resides in a single line at λ = 2.88 nm in the “water window” spectral range, that represents the N2 plasma radiation employed for imaging
The comparison shows a significant improvement of the spatial resolution employing the “water window” radiation where it is possible to observe that the high absorption coefficient at soft X-ray (SXR) wavelengths enhances the optical contrast, allowing to observe some features that are barely visible in Fig. 5 a)

Summary

Introduction

Since the ‘90s, significant efforts were made to bring technical capabilities of synchrotron-based microscopes to the development of compact sources [1]–[8], because that the small size and versatility of compact microscopy system offers the possibility to perform imaging experiments, previously restricted to large-scale facilities, in university laboratories. It was already demonstrated that spatial resolution can be increased in nanoscale imaging systems employing short wavelength radiation such as soft X-ray (SXR) [9] Such radiation has been successfully employed in different microscope techniques, mainly in transmission mode, including scanning microscopy [10], 3D tomography [11] and contact microscopy [12]. Synchrotrons allow imaging acquisition in the “water window” spectral range, with a spatial resolution of ~10 nm [13], a compact high resolution imaging systems is of major importance from the point of view of a worldwide spread and possible commercial applications. The imaging in short wavelength ranges requires a high photon flux For this reason, until now, most of studies in this field are conducted using large scale facilities, such as synchrotron or free-electron laser [14]–[16]. A table-top SXR microscope based on a double stream nitrogen gas puff target, working at the monochromatic wavelength of l=2.88 nm, including its characterization, parameters optimizations and few applications will be presented and discussed

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Results

Conclusion