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Phase-Contrast and High-Resolution Optics for X-Ray Microscopy
KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
2010 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
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.

 

Ort, förlag, år, upplaga, sidor
Stockholm: KTH , 2010. , s. x, 61
Serie
Trita-FYS, ISSN 0280-316X ; 72
Nyckelord [en]
Microscopy, X-ray optics, X-ray microscopy, Soft X-ray physics
Nationell ämneskategori
Atom- och molekylfysik och optik Fysik
Identifikatorer
URN: urn:nbn:se:kth:diva-26781ISBN: 978-91-7415-834-2 (tryckt)OAI: oai:DiVA.org:kth-26781DiVA, id: diva2:372702
Disputation
2010-12-17, FD5, Roslagstullsbacken 21, Stockholm, 15:42 (Engelska)
Opponent
Handledare
Anmärkning
QC 20101130Tillgänglig från: 2010-11-30 Skapad: 2010-11-26 Senast uppdaterad: 2010-11-30Bibliografiskt granskad
Delarbeten
1. Simulation of partially coherent image formation in a compact soft x-ray microscope
Öppna denna publikation i ny flik eller fönster >>Simulation of partially coherent image formation in a compact soft x-ray microscope
2007 (Engelska)Ingår i: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 107, nr 8, s. 604-609Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

In this paper, we describe a numerical method of simulating two-dimensional images in a compact soft X-ray microscope using partially coherent illumination considerations. The work was motivated by recent test object images obtained by the latest generation inhouse compact soft X-ray microscope, which showed diffraction-like artifacts not observed previously. The numerical model approximates the condenser zone plate as a secondary incoherent source represented by individually coherent but mutually incoherent source points, each giving rise to a separate image. A final image is obtained by adding up all the individual source point contributions. The results are compared with the microscope images and show qualitative agreement, indicating that the observed effects are caused by partially coherent illumination.

Nyckelord
Image formation; Partial coherence; X-ray microscopy; Zone plates; Computer simulation; Light sources; Mathematical models; X ray diffraction; X ray microscopes; Incoherent sources; Partial coherence; X ray microscopy; Zone plates; Image processing; article; diffraction; illumination; image analysis; mathematical model; microscopy; qualitative analysis; separation technique; simulation; X ray analysis
Nationell ämneskategori
Fysik
Identifikatorer
urn:nbn:se:kth:diva-7020 (URN)10.1016/j.ultramic.2006.12.001 (DOI)000246937000006 ()2-s2.0-34247139671 (Scopus ID)
Anmärkning
QC 20100820. Uppdaterad från In press till Published 20100820.Tillgänglig från: 2007-04-20 Skapad: 2007-04-20 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
2. Theoretical development of a high-resolution differential-interference-contrast optic for x-ray microscopy
Öppna denna publikation i ny flik eller fönster >>Theoretical development of a high-resolution differential-interference-contrast optic for x-ray microscopy
2008 (Engelska)Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 16, nr 2, s. 1132-1141Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

In this paper, the theoretical background and development of a differential-interference contrast (DIC) x-ray optic is presented. The single-element optic is capable of high-resolution phase contrast imaging and is compatible with compact sources. It is shown that an understanding of the coherence requirements in this type of imaging is imperative and is explained in detail. The optic is capable of a wavefront separation equal to the resolution of the optic which places only minor constraints on the object illumination.

Nyckelord
phase-contrast
Nationell ämneskategori
Den kondenserade materiens fysik
Identifikatorer
urn:nbn:se:kth:diva-17274 (URN)10.1364/OE.16.001132 (DOI)000252479700064 ()18542187 (PubMedID)2-s2.0-38549088419 (Scopus ID)
Anmärkning
QC 20100525Tillgänglig från: 2010-08-05 Skapad: 2010-08-05 Senast uppdaterad: 2020-03-09Bibliografiskt granskad
3. Compact high-resolution differential interference contrast soft x-ray microscopy
Öppna denna publikation i ny flik eller fönster >>Compact high-resolution differential interference contrast soft x-ray microscopy
Visa övriga...
2008 (Engelska)Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, nr 064104Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We demonstrate high-resolution x-ray differential interference contrast (DIC) in a compact soft x-ray microscope. Phase contrast imaging is enabled by the use of a diffractive optical element objective which is matched to the coherence conditions in the microscope setup. The performance of the diffractive optical element objective is evaluated in comparison with a normal zone plate by imaging of a nickel siemens star pattern and linear grating test objects. Images obtained with the DIC optic exhibit typical DIC enhancement in addition to the normal absorption contrast. Contrast transfer functions based on modulation measurements in the obtained images show that the DIC optic gives a significant increase in contrast without reducing the spatial resolution. The phase contrast operation mode now available for our compact soft x-ray microscope will be a useful tool for future studies of samples with low absorption contrast.

Nyckelord
diffractive optical-elements, zone plates, phase-contrast, fabrication, condenser
Nationell ämneskategori
Fysik
Identifikatorer
urn:nbn:se:kth:diva-9811 (URN)10.1063/1.2842422 (DOI)000253237900123 ()2-s2.0-39349084101 (Scopus ID)
Anmärkning
QC 20100728Tillgänglig från: 2009-01-07 Skapad: 2009-01-07 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
4. Compact Zernike phase contrast x-ray microscopy using a single-element optic
Öppna denna publikation i ny flik eller fönster >>Compact Zernike phase contrast x-ray microscopy using a single-element optic
Visa övriga...
2008 (Engelska)Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 33, nr 9, s. 932-934Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We demonstrate Zernike phase contrast in a compact soft x-ray microscope using a single-element optic. The optic is a combined imaging zone plate and a Zernike phase plate and does not require any additional alignment or components. Contrast is increased and inversed in an image of a test object using the Zernike zone plate. This type of optic may be implemented into any existing x-ray microscope where phase contrast is of interest.

Nyckelord
spatial-resolution, zone plates
Nationell ämneskategori
Biomedicinsk laboratorievetenskap/teknologi
Identifikatorer
urn:nbn:se:kth:diva-17561 (URN)10.1364/OL.33.000932 (DOI)000256166900014 ()2-s2.0-44949260817 (Scopus ID)
Anmärkning
QC 20100525Tillgänglig från: 2010-08-05 Skapad: 2010-08-05 Senast uppdaterad: 2020-03-05Bibliografiskt granskad
5. High-resolution computed tomography with a compact soft x-ray microscope
Öppna denna publikation i ny flik eller fönster >>High-resolution computed tomography with a compact soft x-ray microscope
Visa övriga...
2009 (Engelska)Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 17, nr 13, s. 11057-11065Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Computed tomography based on high-resolution soft x-ray microscopy utilizes the natural contrast for biological specimens provided by the water window (lambda = 2.4 - 4.4 nm) and the high resolving power of zone plate objectives. It is capable of revealing the 3D structure of biological specimens at sub-visible-microscopic resolution. To date, the technique has only been available at synchrotron-based microscopes, which limits the researchers access. In the present paper we demonstrate high-resolution soft x-ray tomography with a laboratory zone-plate-based soft x-ray microscope. The specimen, a diatom mounted on a glass capillary, was reconstructed from a tilt series of 53 images covering 180 using a filtered back projection algorithm. The resolution of the tomogram was estimated to a half period of 140 nm using a differential-phase-residual method. Cryo-fixation, increased source brightness and extended-depth-of-focus objectives are important for pushing the resolution of compact systems for biological samples.

Identifikatorer
urn:nbn:se:kth:diva-18584 (URN)10.1364/OE.17.011057 (DOI)000267761100066 ()19550505 (PubMedID)2-s2.0-67649271251 (Scopus ID)
Anmärkning
QC 20100525Tillgänglig från: 2010-08-05 Skapad: 2010-08-05 Senast uppdaterad: 2020-03-09Bibliografiskt granskad
6. Sub-25-nm laboratory x-ray microscopy using a compound Fresnel zone plate
Öppna denna publikation i ny flik eller fönster >>Sub-25-nm laboratory x-ray microscopy using a compound Fresnel zone plate
Visa övriga...
2009 (Engelska)Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 34, nr 17, s. 2631-2633Artikel i tidskrift (Refereegranskat) 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.

Nyckelord
resolution
Identifikatorer
urn:nbn:se:kth:diva-18788 (URN)10.1364/OL.34.002631 (DOI)000270114400031 ()19724514 (PubMedID)2-s2.0-69549105762 (Scopus ID)
Anmärkning
QC 20100525Tillgänglig från: 2010-08-05 Skapad: 2010-08-05 Senast uppdaterad: 2020-03-09Bibliografiskt granskad
7. High-resolution computed tomography with a compact soft x-ray microscope
Öppna denna publikation i ny flik eller fönster >>High-resolution computed tomography with a compact soft x-ray microscope
Visa övriga...
2009 (Engelska)Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 17, nr 13, s. 11057-11065Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Computed tomography based on high-resolution soft x-ray microscopy utilizes the natural contrast for biological specimens provided by the water window (lambda = 2.4 - 4.4 nm) and the high resolving power of zone plate objectives. It is capable of revealing the 3D structure of biological specimens at sub-visible-microscopic resolution. To date, the technique has only been available at synchrotron-based microscopes, which limits the researchers access. In the present paper we demonstrate high-resolution soft x-ray tomography with a laboratory zone-plate-based soft x-ray microscope. The specimen, a diatom mounted on a glass capillary, was reconstructed from a tilt series of 53 images covering 180 using a filtered back projection algorithm. The resolution of the tomogram was estimated to a half period of 140 nm using a differential-phase-residual method. Cryo-fixation, increased source brightness and extended-depth-of-focus objectives are important for pushing the resolution of compact systems for biological samples.

Identifikatorer
urn:nbn:se:kth:diva-18584 (URN)10.1364/OE.17.011057 (DOI)000267761100066 ()19550505 (PubMedID)2-s2.0-67649271251 (Scopus ID)
Anmärkning
QC 20100525Tillgänglig från: 2010-08-05 Skapad: 2010-08-05 Senast uppdaterad: 2020-03-09Bibliografiskt granskad
8. Laboratory X-ray microscopy for high-resolution imaging of environmental colloid structure
Öppna denna publikation i ny flik eller fönster >>Laboratory X-ray microscopy for high-resolution imaging of environmental colloid structure
Visa övriga...
2012 (Engelska)Ingår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 329, nr SI, s. 26-31Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Transmission X-ray microscopy is a uniquely suited technique for studies of environmental colloids since it allows imaging in aqueous media with high spatial resolution, presently down to the 20 nm range. Such nanoscale morphological description of these high-specific-surface-area compounds show promise for improved understanding of soils, sediments or groundwater aquifers. However, present high-quality X-ray microscopes are located at synchrotron radiation facilities resulting in limited applicability and accessibility for colloid scientists. Here we investigate the applicability of a laboratory-scale transmission X-ray microscope for studies of colloids of the environment. The microscope is based on a laser-plasma source in combination with multilayer and zone plate optics. Samples are held at atmospheric pressure in their natural wet state. We show images revealing the nano-scale morphology of the clay nontronite, soils such as chernozem and luvisol, and the mineral hematite, an iron oxide. Comparative studies of dried substances clearly show the need for imaging in the wet state. The image quality approaches that of synchrotron-based microscopes, albeit at longer exposure times. Stereo imaging is investigated as a means for giving 3D information with shorter exposure times than tomography requires. Finally the future development of the laboratory X-ray microscope is discussed, especially with regard to the reduction of exposure times.

Nyckelord
X-ray microscopy, Laser plasma, Diffractive optics, Laboratory scale, environmental colloids, soils
Nationell ämneskategori
Annan fysik
Identifikatorer
urn:nbn:se:kth:diva-26952 (URN)10.1016/j.chemgeo.2011.07.012 (DOI)000310125000005 ()2-s2.0-84866508020 (Scopus ID)
Forskningsfinansiär
Vetenskapsrådet
Anmärkning

QC 20121127

Tillgänglig från: 2010-11-30 Skapad: 2010-11-30 Senast uppdaterad: 2017-12-12Bibliografiskt granskad

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