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Sub-25-nm laboratory x-ray microscopy using a compound Fresnel zone plate
KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.ORCID-id: 0000-0003-2745-6289
Vise andre og tillknytning
2009 (engelsk)Inngår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 34, nr 17, s. 2631-2633Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Improving the resolution in x-ray microscopes is of high priority to enable future applications in nanoscience. However, high-resolution zone-plate optics often have low efficiency, which makes implementation in laboratory microscopes difficult. We present a laboratory x-ray microscope based on a compound zone plate. The compound zone plate utilizes multiple diffraction orders to achieve high resolution while maintaining reasonable efficiency. We analyze the illumination conditions necessary for this type of optics in order to suppress stray light and demonstrate microscopic imaging resolving 25 nm features.

sted, utgiver, år, opplag, sider
2009. Vol. 34, nr 17, s. 2631-2633
Emneord [en]
resolution
Identifikatorer
URN: urn:nbn:se:kth:diva-18788ISI: 000270114400031Scopus ID: 2-s2.0-69549105762OAI: oai:DiVA.org:kth-18788DiVA, id: diva2:336835
Merknad
QC 20100525Tilgjengelig fra: 2010-08-05 Laget: 2010-08-05 Sist oppdatert: 2017-12-12bibliografisk kontrollert
Inngår i avhandling
1. Phase-Contrast and High-Resolution Optics for X-Ray Microscopy
Åpne denne publikasjonen i ny fane eller vindu >>Phase-Contrast and High-Resolution Optics for X-Ray Microscopy
2010 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

X-ray microscopy is a well-established technique for nanoscale imaging. Zone plates are used as microscope objectives and provide high resolution, approaching 10 nm, currently limited by fabrication issues. This Thesis presents zone plate optics that achieve either high resolution or phase contrast in x-ray microscopy. The high-resolution optics use high orders of the zone plate, which alleviates the demands on fabrication, and the phase-contrast optics are single-element diffractive optical elements that produce contrast by Zernike or differential-interference contrast methods. The advantage of phase contrast in x-ray microscopy is shorter exposure times, and is crucial in the hard x-ray regime. Microscopy in the absorption‑contrast region of the water-window (2.34 - 4.37 nm) also benefits from these optics. The development of the optics for a laboratory soft x-ray microscope spans from theoretical and numerical analysis of coherence and stray light to experimental implementation and testing. The laboratory microscope uses laser-produced plasma-sources in the water-window and is unique in its design and performance. It will be shown that the laboratory microscope in its current form is a user-oriented and stable instrument, and has been used in a number of applications. The implementation of a cryogenic sample stage for tomographic imaging of biological samples in their natural environment has enabled applications in biology, and 3D x-ray microscopy of cells was performed for the first time with a laboratory instrument.

 

sted, utgiver, år, opplag, sider
Stockholm: KTH, 2010. s. x, 61
Serie
Trita-FYS, ISSN 0280-316X ; 72
Emneord
Microscopy, X-ray optics, X-ray microscopy, Soft X-ray physics
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-26781 (URN)978-91-7415-834-2 (ISBN)
Disputas
2010-12-17, FD5, Roslagstullsbacken 21, Stockholm, 15:42 (engelsk)
Opponent
Veileder
Merknad
QC 20101130Tilgjengelig fra: 2010-11-30 Laget: 2010-11-26 Sist oppdatert: 2010-11-30bibliografisk kontrollert
2. Laboratory soft x-ray microscopy and tomography
Åpne denne publikasjonen i ny fane eller vindu >>Laboratory soft x-ray microscopy and tomography
2011 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Soft x-ray microscopy in the water-window (λ = 2.28 nm – 4.36 nm) is based on zone-plate optics and allows high-resolution imaging of, e.g., cells and soils in their natural or near-natural environment. Three-dimensional imaging is provided via tomographic techniques, soft x-ray cryo tomography. However, soft x-ray microscopes with such capabilities have been based on large-scale synchrotron x‑ray facilities, thereby limiting their accessibility for a wider scientific community.

This Thesis describes the development of the Stockholm laboratory soft x-ray microscope to three-dimensional cryo tomography and to new optics-based contrast mechanisms. The microscope relies on a methanol or nitrogen liquid-jet laser-plasma source, normal-incidence multilayer or zone-plate condenser optics, in-house fabricated zone-plate objectives, and allows operation at two wavelengths in the water-window, λ = 2.48 nm and λ = 2.48 nm. With the implementation of a new state-of-the-art normal-incidence multilayer condenser for operation at λ = 2.48 nm and a tiltable cryogenic sample stage the microscope now allows imaging of dry, wet or cryo-fixed samples. This arrangement was used for the first demonstration of laboratory soft x-ray cryo microscopy and tomography. The performance of the microscope has been demonstrated in a number of experiments described in this Thesis, including, tomographic imaging with a resolution of 140 nm, cryo microscopy and tomography of various cells and parasites, and for studies of aqueous soils and clays. The Thesis also describes the development and implementation of single-element differential-interference and Zernike phase-contrast zone-plate objectives. The enhanced contrast provided by these optics reduce exposure times or lowers the dose in samples and are of major importance for harder x-ray microscopy. The implementation of a high-resolution 50 nm compound zone-plate objective for sub-25-nm resolution imaging is also described. All experiments are supported by extensive numerical modelling for improved understanding of partially coherent image formation and stray light in soft x-ray microscopes. The models are useful tools for studying effects of zone plate optics or optical design of the microscope on image formation and quantitative accuracy in soft x-ray tomography.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2011. s. x, 76
Serie
Trita-FYS, ISSN 0280-316X ; 2011:03
Emneord
Microscopy, X-ray optics, Diffractive optics, Zone plates, X-ray microscopy, Soft X-ray physics, Tomography
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-29950 (URN)978-91-7415-874-8 (ISBN)
Disputas
2011-02-25, FB42, AlbaNova Universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (engelsk)
Opponent
Veileder
Merknad
QC 20110221Tilgjengelig fra: 2011-02-21 Laget: 2011-02-18 Sist oppdatert: 2011-02-21bibliografisk kontrollert
3. High-Resolution Nanostructuring for Soft X-Ray Zone-Plate Optics
Åpne denne publikasjonen i ny fane eller vindu >>High-Resolution Nanostructuring for Soft X-Ray Zone-Plate Optics
2011 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Diffractive zone-plate lenses are widely used as optics in high-resolution x-ray microscopes. The achievable resolution in such microscopes is presently not limited by the x-ray wavelength but by limitations in zone-plate nanofabrication. Thus, for the advance of high-resolution x-ray microscopy, progress in zone-plate nanofabrication methods are needed.

 

This Thesis describes the development of new nanofabrication processes for improved x-ray zone-plate optics. Cold development of the electron-beam resist ZEP7000 is applied to improve the resolution of soft x-ray Ni zone plates. The influence of developer temperature on resist contrast, resolution, and pattern quality is investigated. With an optimized process, Ni zone plates with outermost zone widths down to 13 nm are demonstrated. To enhance the diffraction efficiency of Ni zone plates, the concept of Ni-Ge zone plates is introduced. The applicability of Ni-Ge zone plates is first demonstrated in a proof-of-principle experiment, and then extended to cold-developed Ni zone plates with outermost zone widths down to 13 nm. For 15-nm Ni-Ge zone plates a diffraction efficiency of 4.3% at a wavelength of 2.88 nm is achieved, which is about twice the efficiency of state-of-the-art 15-nm Ni zone plates. To further increase both resolution and diffraction efficiency of soft x-ray zone plates, a novel fabrication process for W zone plates is developed. High resolution is provided by salty development of the inorganic electron-beam resist HSQ, and cryogenic RIE in a SF6 plasma is investigated for high-aspect-ratio W structuring. We demonstrate W zone plates with 12-nm outermost zone width and a W height of 90 nm, resulting in a 30% increase in theoretical diffraction efficiency compared to 13-nm efficiency-enhanced Ni-Ge zone plates. In addition to soft x-ray zone plates, some lenses for hard x-ray free-electron-laser applications were also fabricated during this Thesis work. Fabrication processes for the materials W, diamond, and Pt were developed. We demonstrate Pt and W-diamond zone plates with 100-nm outermost zone width and respective diffraction efficiencies of 8.2% and 14.5% at a photon energy of 8 keV.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2011. s. xii, 70
Serie
Trita-FYS, ISSN 0280-316X ; 2011:55
Emneord
zone plates; x-ray optics; x-ray microscopy; high resolution; nanofabrication; electron beam lithography; reactive ion etching; tungsten; nickel; germanium
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-47409 (URN)978-91-7501-175-2 (ISBN)
Disputas
2011-12-02, FA31, Roslagstullsbacken 21, KTH/Albanova, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Merknad
QC 20111114Tilgjengelig fra: 2011-11-14 Laget: 2011-11-08 Sist oppdatert: 2011-11-14bibliografisk kontrollert

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