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Publications (10 of 12) Show all publications
Mi, W., Karlsson, S., Holmberg, A., Danielsson, M. & Nillius, P. (2016). Fabrication of circular sawtooth gratings using focused UV lithography. Journal of Micromechanics and Microengineering, 26(3), 1-7, Article ID 035001.
Open this publication in new window or tab >>Fabrication of circular sawtooth gratings using focused UV lithography
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2016 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 26, no 3, p. 1-7, article id 035001Article in journal (Refereed) Published
Abstract [en]

AbstractThis paper presents a novel micro-fabrication method using focused ultraviolet (UV) light to manufacture three-dimensional sawtooth structures in ultra-thick negative photoresist to fabricate a novel multi-prism x-ray lens. The method uses a lens to shape the UV beam instead of the photomask conventionally used in UV lithography. Benefits of this method include the ability to manufacture sawtooth structures in free form, for example in circular shapes as well as arrays of these shapes, and in resist that is up to 76 μm thick.To verify the method, initially a simple simulation based on Fourier optics was done to predict the exposure energy distribution in the photoresist. Furthermore, circular sawtooth gratings were manufactured in a 76 μm SU-8 resist. The UV lens was fabricated using electron beam lithography and then used to expose the SU-8 with UV light. This paper details the complete developed process, including pre-exposure with an e-beam and cold development, which creates stable sawtooth structures. The measured profile was compared to the ideal sawtooth and the simulation. The main discrepancy was in the smallest feature size, the sawtooth tips, which were wider than the desired structures, as would be expected by simulation.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2016
Keywords
focused UV lithography, three-dimensional sawtooth structures, SU-8, UV lens, Fourier optics
National Category
Medical Engineering
Research subject
Medical Technology; Physics; Applied Medical Technology
Identifiers
urn:nbn:se:kau:diva-63912 (URN)10.1088/0960-1317/26/3/035001 (DOI)000375230700001 ()2-s2.0-84959432882 (Scopus ID)
Projects
Medical Imaging Project
Funder
Stiftelsen Olle Engkvist Byggmästare
Available from: 2017-09-22 Created: 2017-09-22 Last updated: 2019-05-20Bibliographically approved
Nachtrab, F., Hofmann, T., Speier, C., Lucic, J., Firsching, M., Uhlmann, N., . . . Sauerwein, C. (2015). Development of a Timepix based detector for the NanoXCT project. Paper presented at 17th International Workshop on Radiation Imaging Detectors, JUN 28-JUL 02, 2015, DESY, Hamburg, GERMANY. Journal of Instrumentation, 10, Article ID C11009.
Open this publication in new window or tab >>Development of a Timepix based detector for the NanoXCT project
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2015 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 10, article id C11009Article in journal (Refereed) Published
Abstract [en]

The NanoXCT EU FP7 project [1] aims at developing a laboratory, i.e. bench top sized X-ray nano-CT system with a large field-of-view (FOV) for non-destructive testing needs in the micro- and nano-technology sector. The targeted voxel size is 50 nm at 0.175 mm FOV, the maximum FOV is 1 mm at 285 nm voxel size. Within the project a suitable X-ray source, detector and manipulation system have been developed. The system concept [2] omits the use of X-ray optics, to be able to provide a large FOV of up to 1 mm and to preserve the flexibility of state-of-the-art micro-CT systems. The targeted resolution will be reached via direct geometric magnification made possible by the development of a specialized high-flux nano-focus transmission X-ray tube. The end-user's demand for elemental analysis will be covered by energy-resolved measurement techniques, in particular a K-edge imaging method. Timepix [3] modules were chosen as the basis for the detector system, since a photon counting detector is advantageous for the long exposure times that come with very small focal spot sizes. Additional advantages are the small pixel size and adjustable energy threshold. To fulfill the requirements on field-of-view, a detector width > 3000 pixels was needed. The NanoXCT detector consists of four Hexa modules with 500 mu m silicon sensors supplied by X-ray Imaging Europe. An adapter board was developed to connect all four modules to one Fitpix3 readout. The final detector has an active area of 3072 x 512 pixels or approximately 17 x 3 cm(2). In this contribution we present the development of the Timepix based NanoXCT detector, it's application in the NanoXCT project for CT and material specific measurements and the current status of results.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2015
Keywords
Detector design and construction technologies and materials, Inspection with x-rays, Detection of defects, Detector alignment and calibration methods (lasers, sources, particle-beams)
National Category
Medical Image Processing
Research subject
Physics
Identifiers
urn:nbn:se:kau:diva-63914 (URN)10.1088/1748-0221/10/11/C11009 (DOI)000367676000009 ()2-s2.0-84948780957 (Scopus ID)
Conference
17th International Workshop on Radiation Imaging Detectors, JUN 28-JUL 02, 2015, DESY, Hamburg, GERMANY
Available from: 2017-09-22 Created: 2017-09-22 Last updated: 2019-05-20Bibliographically approved
Selin, M., Fogelqvist, E., Holmberg, A., Guttmann, P., Vogt, U. & Hertz, H. M. (2014). 3D simulation of the image formation in soft x-ray microscopes. Optics Express, 22(25), 30756-30768
Open this publication in new window or tab >>3D simulation of the image formation in soft x-ray microscopes
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2014 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 22, no 25, p. 30756-30768Article in journal (Refereed) Published
Abstract [en]

In water-window soft x-ray microscopy the studied object is typically larger than the depth of focus and the sample illumination is often partially coherent. This blurs out-of-focus features and may introduce considerable fringing. Understanding the influence of these phenomena on the image formation is therefore important when interpreting experimental data. Here we present a wave-propagation model operating in 3D for simulating the image formation of thick objects in partially coherent soft x-ray microscopes. The model is compared with present simulation methods as well as with experiments. The results show that our model predicts the image formation of transmission soft x-ray microscopes more accurately than previous models.

Place, publisher, year, edition, pages
Optical Society of America, 2014
Keywords
Wave propagation, X ray microscopes, 3D simulations, Depth of focus, Out-of-focus, Partially coherent, Propagation modeling, Soft X-ray, Soft x-ray microscopy
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:kau:diva-63917 (URN)10.1364/OE.22.030756 (DOI)000346368800068 ()2-s2.0-84919663855 (Scopus ID)
Funder
Swedish Research Council
Available from: 2017-09-22 Created: 2017-09-22 Last updated: 2019-05-20Bibliographically approved
Uhlén, F., Nilsson, D., Rahomäki, J., Belova, L., Schroer, C. G., Seiboth, F., . . . Vogt, U. (2014). Nanofabrication of tungsten zone plates with integrated platinum central stop for hard X-ray applications. Microelectronic Engineering, 116, 40-43
Open this publication in new window or tab >>Nanofabrication of tungsten zone plates with integrated platinum central stop for hard X-ray applications
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2014 (English)In: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 116, p. 40-43Article in journal (Refereed) Published
Abstract [en]

We present a nanofabrication process for producing tungsten zone plates used in hard X-ray applications including a method of integrating a high-energy absorbing central stop with the optic. Tungsten zone plates are structured with electron-beam lithography and subsequent reactive ion etching. The central stop originates from a platinum wire. It is cut to dimension by focused ion beam etching, and afterwards attached to the zone plate center using ion beam induced deposition of platinum. A zone plate with integrated central stop will simplify alignment in hard X-ray scanning microscope arrangements where the 0th order light must be eliminated. The focusing performance of the zone plate device was investigated by scanning coherent diffraction imaging (ptychography) at 8 keV photon energy. We could demonstrate a diffraction-limited focus size of 53 nm diameter full-width-at-half-maximum. Tungsten zone plates with integrated central stops show promising results for use in hard X-ray microscopes at high-brightness facilities.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Hard X-ray microscopy, Platinum, Ptychography, Tungsten, X-ray diffractive optics, Zone plates
National Category
Other Physics Topics
Research subject
Physics
Identifiers
urn:nbn:se:kau:diva-63919 (URN)10.1016/j.mee.2013.10.011 (DOI)000331161300008 ()2-s2.0-84892374286 (Scopus ID)
Funder
Swedish Foundation for Strategic Research Swedish Research CouncilEU, FP7, Seventh Framework Programme, 226716]
Available from: 2017-09-22 Created: 2017-09-22 Last updated: 2019-05-20Bibliographically approved
Nachtrab, F., Firsching, M., Speier, C., Uhlmann, N., Takman, P., Tuohimaa, T., . . . Sauerwein, C. (2014). NanoXCT: Development of a laboratory nano-CT system. In: Stuart R. Stock (Ed.), Proceedings of SPIE - The International Society for Optical Engineering: . Paper presented at Developments in X-Ray Tomography IX Event: SPIE Optical Engineering + Applications,18 August 2014 through 20 August 2014, San Diego, California, United States. SPIE - International Society for Optical Engineering, 9212
Open this publication in new window or tab >>NanoXCT: Development of a laboratory nano-CT system
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2014 (English)In: Proceedings of SPIE - The International Society for Optical Engineering / [ed] Stuart R. Stock, SPIE - International Society for Optical Engineering, 2014, Vol. 9212Conference paper, Published paper (Refereed)
Abstract [en]

The NanoXCT project aims at developing a laboratory nano-CT system for non-destructive testing applications in the micro- and nano-technology sector. The system concept omits the use of X-ray optics, to be able to provide up to 1 mm FOV (at 285 nm voxel size) and down to 50 nm voxel size (at 0.175 mm FOV) while preserving the flexibility of state-of-the-art micro-CT systems. Within the project a suitable X-ray source, detector and manipulation system are being developed. To cover the demand for elemental analysis, the project will additionally include X-ray spectroscopic techniques. These will be reported elsewhere while this paper is focused on the imaging part of the project. We introduce the system concept including design goals and constraints, and the individual components. We present the current state of the prototype development including first results.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2014
Keywords
Computed tomography, Nano-CT, Nano-focus, NanoXCT, Photon-counting X-ray detector, Timepix detector, Transmission tube, Imaging systems, Nondestructive examination, Spectroscopic analysis, Tomography, X ray apparatus, X ray spectroscopy, Timepix detectors, X-ray detector, Computerized tomography
National Category
Medical Engineering
Identifiers
urn:nbn:se:kau:diva-63913 (URN)10.1117/12.2061752 (DOI)000344554400017 ()2-s2.0-84923031242 (Scopus ID)9781628412390 (ISBN)
Conference
Developments in X-Ray Tomography IX Event: SPIE Optical Engineering + Applications,18 August 2014 through 20 August 2014, San Diego, California, United States
Available from: 2017-09-22 Created: 2017-09-22 Last updated: 2019-05-20Bibliographically approved
Uhlén, F., Nilsson, D., Holmberg, A., Hertz, H. M., Schroer, C. G., Seiboth, F., . . . Vogt, U. (2013). Damage investigation on tungsten and diamond diffractive optics at a hard x-ray free-electron laser. Optics Express, 21(7), 8051-8061
Open this publication in new window or tab >>Damage investigation on tungsten and diamond diffractive optics at a hard x-ray free-electron laser
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2013 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 21, no 7, p. 8051-8061Article in journal (Refereed) Published
Abstract [en]

Focusing hard x-ray free-electron laser radiation with extremely high fluence sets stringent demands on the x-ray optics. Any material placed in an intense x-ray beam is at risk of being damaged. Therefore, it is crucial to find the damage thresholds for focusing optics. In this paper we report experimental results of exposing tungsten and diamond diffractive optics to a prefocused 8.2 keV free-electron laser beam in order to find damage threshold fluence levels. Tungsten nanostructures were damaged at fluence levels above 500 mJ/cm(2). The damage was of mechanical character, caused by thermal stress variations. Diamond nanostructures were affected at a fluence of 59 000 mJ/cm(2). For fluence levels above this, a significant graphitization process was initiated. Scanning Electron Microscopy (SEM) and mu-Raman analysis were used to analyze exposed nanostructures.

Place, publisher, year, edition, pages
Optical Society America, 2013
Keywords
X-ray optics, Zone plate, XFEL
National Category
Other Physics Topics
Research subject
Physics
Identifiers
urn:nbn:se:kau:diva-63918 (URN)10.1364/OE.21.008051 (DOI)000317659300021 ()2-s2.0-84875987203 (Scopus ID)
Funder
Swedish Research Council
Available from: 2017-09-22 Created: 2017-09-22 Last updated: 2019-05-20Bibliographically approved
Vogt, U., Reinspach, J., Uhlén, F., Nilsson, D., Hertz, H. M. & Holmberg, A. (2013). Diffractive optics for laboratory sources to free electron lasers. In: 11th International Conference On X-Ray Microscopy (XRM2012): . Paper presented at 11th International Conference on X-Ray Microscopy, XRM 2012, Shanghai, China, 5-10 August 2012 (pp. 012001). Institute of Physics (IOP)
Open this publication in new window or tab >>Diffractive optics for laboratory sources to free electron lasers
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2013 (English)In: 11th International Conference On X-Ray Microscopy (XRM2012), Institute of Physics (IOP), 2013, p. 012001-Conference paper, Published paper (Refereed)
Abstract [en]

In this contribution we present our recent results in the field of diffractive optics for both soft and hard x-ray radiation, and for laboratory sources to x-ray free electron lasers (XFEL). We developed a laboratory soft x-ray microscope that uses in-house produced zone plate optics as high-resolution objectives. We continuously try to improve these optics, both in terms of efficiency and resolution. Our latest development is the manufacturing of tungsten soft x-ray zone plates with outermost zone widths of 12 nm and 90 nm high structures. For hard x-rays, we investigated the possibility to use metal zone plates on a diamond substrate for nano-focusing of the European X-ray Free Electron Laser. The simulations show that the heat conduction is efficient enough to keep a zone plate well below melting temperature. However, metal zone plates will experience large and rapid temperature fluctuations of several hundred Kelvin that might prove fatal. To test this, we manufactured tungsten on diamond prototype zone plates and exposed them to radiation from the LCLS XFEL. Results show that metal zone plates can survive the XFEL beam.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2013
Series
Journal of Physics Conference Series, ISSN 1742-6588 ; 463
Keywords
Zone Plates, Fabrication
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:kau:diva-63920 (URN)10.1088/1742-6596/463/1/012001 (DOI)000327949000001 ()2-s2.0-84891306833 (Scopus ID)
Conference
11th International Conference on X-Ray Microscopy, XRM 2012, Shanghai, China, 5-10 August 2012
Available from: 2017-09-22 Created: 2017-09-22 Last updated: 2019-05-20Bibliographically approved
Welch, C. C., Olynick, D. L., Liu, Z., Holmberg, A., Peroz, C., Robinson, A. P. G., . . . Ng, D. K. T. (2012). Formation of nanoscale structures by inductively coupled plasma etching. In: Alexander A. Orlikovsky (Ed.), International Conference Micro- and Nano-Electronics 2012: . Paper presented at International Conference on Micro- and Nanoelectronics 2012, ICMNE 2012; Zvenigorod; Russian Federation; 1 October 2012 through 5 October 2012 (pp. 870002). SPIE - International Society for Optical Engineering
Open this publication in new window or tab >>Formation of nanoscale structures by inductively coupled plasma etching
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2012 (English)In: International Conference Micro- and Nano-Electronics 2012 / [ed] Alexander A. Orlikovsky, SPIE - International Society for Optical Engineering, 2012, p. 870002-Conference paper, Published paper (Refereed)
Abstract [en]

This paper will review the top down technique of ICP etching for the formation of nanometer scale structures. The increased difficulties of nanoscale etching will be described. However it will be shown and discussed that inductively coupled plasma (ICP) technology is well able to cope with the higher end of the nanoscale: features from 100nm down to about 40nm are relatively easy with current ICP technology. It is the ability of ICP to operate at low pressure yet with high plasma density and low (controllable) DC bias that helps greatly compared to simple reactive ion etching (RIE) and, though continual feature size reduction is increasingly challenging, improvements to ICP technology as well as improvements in masking are enabling sub-10nm features to be reached. Nanoscale ICP etching results will be illustrated in a range of materials and technologies. Techniques to facilitate etching (such as the use of cryogenic temperatures) and techniques to improve the mask performance will be described and illustrated.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2012
Series
Proceedings of SPIE - The International Society for Optical Engineering, ISSN 0277-786X ; 8700
Keywords
Cryogenic, Etching, ICP, Nanoscale, Nanotechnology, Cryogenic temperatures, Feature sizes, Inductively coupled plasma (ICP), Materials and technologies, Nano scale, Nanometer scale structure, Nanoscale structure, Cryogenics, Inductively coupled plasma, Plasma density, Technology, Nanoelectronics
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:kau:diva-63921 (URN)10.1117/12.2017609 (DOI)000322818600001 ()2-s2.0-84880210643 (Scopus ID)
Conference
International Conference on Micro- and Nanoelectronics 2012, ICMNE 2012; Zvenigorod; Russian Federation; 1 October 2012 through 5 October 2012
Available from: 2017-09-22 Created: 2017-09-22 Last updated: 2019-05-20Bibliographically approved
Martz, D. H., Selin, M., von Hofsten, O., Fogelqvist, E., Holmberg, A., Vogt, U., . . . Hertz, H. M. (2012). High average brightness water window source for short-exposure cryomicroscopy. Optics Letters, 37(21), 4425-4427
Open this publication in new window or tab >>High average brightness water window source for short-exposure cryomicroscopy
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2012 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 37, no 21, p. 4425-4427Article in journal (Refereed) Published
Abstract [en]

Laboratory water window cryomicroscopy has recently demonstrated similar image quality as synchrotron-based microscopy but still with much longer exposure times, prohibiting the spread to a wider scientific community. Here we demonstrate high-resolution laboratory water window imaging of cryofrozen cells with 10 s range exposure times. The major improvement is the operation of a lambda = 2.48 nm, 2 kHz liquid nitrogen jet laser plasma source with high spatial and temporal stability at high average brightness >1.5 x 10(12) ph/(s x sr x mu m(2) x line), i.e., close to that of early synchrotrons. Thus, this source enables not only biological x-ray microscopy in the home laboratory but potentially other applications previously only accessible at synchrotron facilities.

Place, publisher, year, edition, pages
Optical Society of America, 2012
Keywords
X-Ray Microscopy
National Category
Other Physics Topics
Research subject
Physics
Identifiers
urn:nbn:se:kau:diva-63911 (URN)10.1364/OL.37.004425 (DOI)000310577700024 ()2-s2.0-84868308552 (Scopus ID)
Funder
Swedish Research CouncilSwedish Foundation for Strategic Research
Available from: 2017-09-22 Created: 2017-09-22 Last updated: 2019-05-20Bibliographically approved
Hertz, H., von Hofsten, O., Bertilson, M., Vogt, U., Holmberg, A., Reinspach, J. A., . . . Svärd, S. (2012). Laboratory cryo soft X-ray microscopy. Journal of Structural Biology, 177(2), 267-272
Open this publication in new window or tab >>Laboratory cryo soft X-ray microscopy
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2012 (English)In: Journal of Structural Biology, ISSN 1047-8477, E-ISSN 1095-8657, Vol. 177, no 2, p. 267-272Article in journal (Refereed) Published
Abstract [en]

Lens-based water-window X-ray microscopy allows two- and three-dimensional (2D and 3D) imaging of intact unstained cells in their near-native state with unprecedented contrast and resolution. Cryofixation is essential to avoid radiation damage to the sample. Present cryo X-ray microscopes rely on synchrotron radiation sources, thereby limiting the accessibility for a wider community of biologists. In the present paper we demonstrate water-window cryo X-ray microscopy with a laboratory-source-based arrangement. The microscope relies on a lambda = 2.48-nm liquid-jet high-brightness laser-plasma source, normal-incidence multilayer condenser optics, 30-nm zone-plate optics, and a cryo sample chamber. We demonstrate 2D imaging of test patterns, and intact unstained yeast, protozoan parasites and mammalian cells. Overview 3D information is obtained by stereo imaging while complete 3D microscopy is provided by full tomographic reconstruction. The laboratory microscope image quality approaches that of the synchrotron microscopes, but with longer exposure times. The experimental image quality is analyzed from a numerical wave-propagation model of the imaging system and a path to reach synchrotron-like exposure times in laboratory microscopy is outlined.

Place, publisher, year, edition, pages
Elsevier, 2012
Keywords
X-ray microscopy, Cryo fixation, Laboratory, Parasites
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kau:diva-63909 (URN)10.1016/j.jsb.2011.11.015 (DOI)000300755400011 ()22119891 (PubMedID)2-s2.0-84857033171 (Scopus ID)
Funder
Swedish Research Council
Available from: 2017-09-22 Created: 2017-09-22 Last updated: 2019-05-20Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2745-6289

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