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  • 1.
    Burvall, Anna
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Axicon imaging by scalar diffraction theory2004Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Axicons are optical elements that produce Bessel beams,i.e., long and narrow focal lines along the optical axis. Thenarrow focus makes them useful ine.g. alignment, harmonicgeneration, and atom trapping, and they are also used toincrease the longitudinal range of applications such astriangulation, light sectioning, and optical coherencetomography. In this thesis, axicons are designed andcharacterized for different kinds of illumination, using thestationary-phase and the communication-modes methods.

    The inverse problem of axicon design for partially coherentlight is addressed. A design relation, applicable toSchell-model sources, is derived from the Fresnel diffractionintegral, simplified by the method of stationary phase. Thisapproach both clarifies the old design method for coherentlight, which was derived using energy conservation in raybundles, and extends it to the domain of partial coherence. Thedesign rule applies to light from such multimode emitters aslight-emitting diodes, excimer lasers and some laser diodes,which can be represented as Gaussian Schell-model sources.

    Characterization of axicons in coherent, obliqueillumination is performed using the method of stationary phase.It is shown that in inclined illumination the focal shapechanges from the narrow Bessel distribution to a broadasteroid-shaped focus. It is proven that an axicon ofelliptical shape will compensate for this deformation. Theseresults, which are all confirmed both numerically andexperimentally, open possibilities for using axicons inscanning optical systems to increase resolution and depthrange.

    Axicons are normally manufactured as refractive cones or ascircular diffractive gratings. They can also be constructedfrom ordinary spherical surfaces, using the sphericalaberration to create the long focal line. In this dissertation,a simple lens axicon consisting of a cemented doublet isdesigned, manufactured, and tested. The advantage of the lensaxicon is that it is easily manufactured.

    The longitudinal resolution of the axicon varies. The methodof communication modes, earlier used for analysis ofinformation content for e.g. line or square apertures, isapplied to the axicon geometry and yields an expression for thelongitudinal resolution. The method, which is based on abi-orthogonal expansion of the Green function in the Fresneldiffraction integral, also gives the number of degrees offreedom, or the number of information channels available, forthe axicon geometry.

    Keywords:axicons, diffractive optics, coherence,asymptotic methods, communication modes, information content,inverse problems

  • 2.
    Burvall, Anna
    et al.
    National university of Ireland, Galway.
    Barrett, Harrison H.
    University of Arizona.
    Dainty, Christopher
    National University of Ireland, Galway.
    Myers, Kyle J.
    U.S. Food and Drug Administration Laboratory for the Assessment of Medical Imaging Systems.
    Singular-value decomposition for through-focus imaging systems2006In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 23, no 10, p. 2440-2448Article in journal (Refereed)
    Abstract [en]

    Singular-value decomposition (SVD) of a linear imaging system gives information on the null and measurement components of object and image and provides a method for object reconstruction from image data. We apply SVD to through-focus imaging systems that produce several two-dimensional images of a three-dimensional object. Analytical expressions for the singular functions are derived in the geometrical approximation for a telecentric, laterally shift-invariant system linear in intensity. The modes are evaluated numerically, and their accuracy confirmed. Similarly, the modes are derived and evaluated for a continuous image representing the limit of a large number of image planes.

  • 3.
    Burvall, Anna
    et al.
    National university of Ireland, Galway.
    Barrett, Harrison H.
    Dainty, Christopher
    National university of Ireland, Galway.
    Myers, Kyle J.
    Singular-value decomposition of axial systems2006In: ICO Topical meeting on optoinformation/Information Photonics 2006, 2006Conference paper (Other academic)
    Abstract [en]

    A method for reconstruction of 3D objects from 2D images, used e.g. in fluorescence microscopy, is takingseveral images along the axial direction. Singular-value decomposition is used to perform the reconstructionand determine its limits.

  • 4.
    Burvall, Anna
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Barrett, Harrison H.
    Myers, Kyle J.
    Dainty, Christopher
    Singular-value decomposition of a tomosynthesis system2010In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 18, no 20, p. 20699-20711Article in journal (Refereed)
    Abstract [en]

    Tomosynthesis is an emerging technique with potential to replace mammography, since it gives 3D information at a relatively small increase in dose and cost. We present an analytical singular-value decomposition of a tomosynthesis system, which provides the measurement component of any given object. The method is demonstrated on an example object. The measurement component can be used as a reconstruction of the object, and can also be utilized in future observer studies of tomosynthesis image quality.

  • 5.
    Burvall, Anna
    et al.
    National University of Ireland, Galway.
    Daly, Elisabeth
    National University of Ireland, Galway.
    Chamot, Stephane R.
    Swiss Federal Polytechnic School of Lausanne.
    Dainty, Chris
    National University of Ireland, Galway.
    Linearity of the pyramid wavefront sensor2006In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 14, no 25, p. 11925-11934Article in journal (Refereed)
    Abstract [en]

    The pyramid wavefront sensor is very similar to the Fourier knife-edge test, but employs dynamic modulation to quantify the phase derivative. For circular modulation, we compare approximate geometrical optics calculations, more exact diffraction calculations, and experimental results. We show that both the sinusoidal and the approximate linear relationship between wavefront derivative and wavefront sensor response can be derived rigorously from diffraction theory. We also show that geometrical, diffraction and experimental results are very similar, and conclude that the approximate geometrical predictions can be used in place of the more complex diffraction results.

  • 6.
    Burvall, Anna
    et al.
    National University of Ireland, Galway.
    Goncharov, Alexander
    National university of Irelan, Galway.
    Dainty, Christopher
    National University of Ireland, Galway.
    Diffraction analysis of lens axicons2005In: Diffractive Optics 2005, European Optical Society , 2005, p. 1-2Conference paper (Other academic)
    Abstract [en]

    Axicons, as shown in Fig. 1(a), are optical elements that produce long and narrow focallines along the optical axis, rather than the conventional focal point created by a lens. Thefocal line can be used for e.g. alignment, extending the focal depth of existing methods, orparticle trapping and transportation. Axicons are mainly produced as refractive glass cones,or as di®ractive gratings consisting of concentric circles. They can also be constructed fromordinary lenses or lens systems, referred to as lens axicons. There are several lens axicondesigns, using spherical or aspheric surfaces to produce the necessary amount of sphericalaberration.

  • 7.
    Burvall, Anna
    et al.
    National University of Ireland, Galway.
    Goncharov, Alexander
    National University of Ireland, Galway.
    Dainty, Christopher
    National university of Ireland, Galway.
    Telephoto axicon2005In: Proceedings of SPIE / [ed] Laurent Mazuray, Rolf Wartmann, SPIE - International Society for Optical Engineering, 2005Conference paper (Other academic)
    Abstract [en]

    The axicon is an optical element which creates a narrow focal line along the optical axis, unlike the single focal point produced by a lens. The long and precisely defined axicon focal line is used e.g. in alignment, or to extend the depth of focus of existing methods such as optical coherence tomography or light sectioning. Axicons are generally manufactured as refractive cones or diffractive circular gratings. They are also made as lens systems or doublet lenses, which are easier to produce. We present a design in the form of a reflective-refractive single-element device with annular aperture. This very compact system has only two surfaces, which can be spherical or aspheric depending on the quality required of the focal line. Both surfaces have reflective coatings at specific zones, providing an annular beam suitable for generating extended focal lines. One draw-back of a normal axicon is its sensitivity to the angle of illumination. Even for relatively small angles, astigmatism will broaden the focus and give it an asteroid shape. For our design, with spherical surfaces concentric about the center of the entrance pupil, the focal line remains unchanged in off-axis illumination.

  • 8.
    Burvall, Anna
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Kolacz, K.
    Jaroszewicz, Z.
    Friberg, Ari T.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Simple lens axicon2004In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 43, no 25, p. 4838-4844Article in journal (Refereed)
    Abstract [en]

    We present the design of a cemented doublet-lens axicon made from spherical surfaces only. Compared with diffractive axicons, refractive cone axicons, and earlier lens axicons with aspheric surfaces, this element is inexpensive and easy to manufacture even with large apertures. The lens axicon is based on the deliberate use of the spherical aberration of the surfaces. The design principles of the element and its characterization, numerically and experimentally, are presented in detail. Although performance was traded for simplicity and robustness, the results show that the lens axicon has the main axicon properties: a narrow, extended line focus of relatively constant width.

  • 9.
    Burvall, Anna
    et al.
    National University of Ireland, Galway.
    Kolacz, Katarzyna
    Institute of Applied Optics, Warsaw.
    Goncharov, Alexander
    National University of Ireland, Galway.
    Jaroszewicz, Zbigniew
    Institute of Applied Optics, Warsaw.
    Dainty, Christopher
    National University of Ireland, Galway.
    Lens axicons in oblique illumination2007In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 46, no 3, p. 312-318Article in journal (Refereed)
    Abstract [en]

    Lens axicons, i.e., lenses or lens systems designed to work like axicons, can be a simple and inexpensive way of generating the characteristic axicon focal line. In the design of most lens axicons, only on-axis properties have been considered. We present the design of a lens axicon with improved off-axis characteristics. It is constructed from a singlet lens but with a double-pass feature that allows for a line of uniform width and a stop positioned to minimize aberrations. We perform off-axis analysis and experiments for this system and for another lens axicon, one designed for its on-axis characteristics. We conclude that the off-axis performance of the double-pass axicon is better than both that of an ordinary cone axicon and that of the other lens axicon.

  • 10.
    Burvall, Anna
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Stig, Fredrik
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Hallström, Stefan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Phase-retrieval methods with applications in composite-material tomography2013In: 11th International Conference On X-Ray Microscopy (XRM2012), Institute of Physics Publishing (IOPP), 2013, p. 012015-Conference paper (Refereed)
    Abstract [en]

    In-line phase-contrast x-ray imaging is emerging as a method for observing small details when the contrast in absorption x-ray imaging is low. It gives images with strong edge enhancement, and phase retrieval is necessary to obtain quantitative thickness information. In particular for tomography, clarity can be enhanced by phase retrieval, as here demonstrated on a 3D-weave reinforced composite material. Seven suitable phase-retrieval methods are identified and integrated into a single method, where each version is marked by variations in particular steps. The general method and its variations are outlined and a comparison shows which methods are most suitable in different situations.

  • 11.
    Burvall, Anna
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundstrom, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Takman, Per A. C.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Phase retrieval in X-ray phase-contrast imaging suitable for tomography2011In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 19, no 11, p. 10359-10376Article in journal (Refereed)
    Abstract [en]

    In-line phase-contrast X-ray imaging provides images where both absorption and refraction contribute. For quantitative analysis of these images, the phase needs to be retrieved numerically. There are many phase-retrieval methods available. Those suitable for phase-contrast tomography, i.e., non-iterative phase-retrieval methods that use only one image at each projection angle, all follow the same pattern though derived in different ways. We outline this pattern and use it to compare the methods to each other, considering only phase-retrieval performance and not the additional effects of tomographic reconstruction. We also outline derivations, approximations and assumptions, and show which methods are similar or identical and how they relate to each other. A simple scheme for choosing reconstruction method is presented, and numerical phase-retrieval performed for all methods.

  • 12.
    Burvall, Anna
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Takman, Per
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Larsson, Daniel
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    X-ray in-line phase retrieval for tomography2012In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE, SPIE - International Society for Optical Engineering, 2012, Vol. 8313, p. 83136A-Conference paper (Refereed)
    Abstract [en]

    Phase contrast in X-ray imaging offers imaging of fine features at lower doses than absorption. Of the phasecontrast methods in use in-line phase contrast is interesting due to its experimental simplicity, but to extract information on absorption and phase distributions from the resulting images, phase retrieval is needed. Many phase-retrieval methods suitable for different situations have been developed, but few comparisons of those methods done. We consider a sub-group of phase-retrieval methods that are suitable for tomography, i.e., that use only one exposure (for practical experimental reasons) and are non-iterative (for speed). In total we have found seven suitable methods in the literature. All, though derived in different ways under different assumptions, follow the same pattern and can be outlined as a single method where each specific version is marked by variations in particular steps. We summarize this unified approach, and give the variations of the individual methods. In addition, we outline approximations and assumptions of each method. Using this approach it is possible to conclude which specific algorithms are most suitable in specific situations and to test this based on simulated and experimental data. Ultimately, this leads to conclusions on which methods are the most suitable in different situations.

  • 13.
    Burvall, Anna
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Martinsson, Per
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Friberg, Ari
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Communication modes applied to axicons2004In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 12, no 3, p. 377-383Article in journal (Refereed)
    Abstract [en]

    The communication modes, which constitute a convenient method for the propagation and information analysis of optical fields, are formulated in the generalized axicon geometry. The transmitting region is the axicon’s annular aperture, and the observation domain is the optical axis containing the focal line segment. We show that in rotational symmetry one may employ the prolate spheroidal wave functions to represent the communication modes. Further, in usual circumstances the modes can be approximated by quadratic waves in the aperture domain and by sinc functions in the image domain. Both the exact communication modes and the approximate technique are confirmed numerically, with linear axicons as examples.

  • 14.
    Burvall, Anna
    et al.
    Applied Optics, Dept. of Experimental Physics, National University of Ireland, Galway, University Road, Galway, Ireland.
    Martinsson, Per
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Friberg, Ari
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Communication modes for information content analysis2004In: LFNM 2004: PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON LASER AND FIBER-OPTICAL NETWORKS MODELING / [ed] Sukhoivano, IA, IEEE conference proceedings, 2004, p. 112-114Conference paper (Other academic)
    Abstract [en]

    Approximate modes which give physical understanding for the communication modes theory,are discussed. For the geometry consisting of two line or square apertures, perpendicular to the optical axis, this approximation leads to exactly the same modes as Gabor's theory would yield.

  • 15.
    Burvall, Anna
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Martinsson, Per
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Communication modes in large-aperture approximation2007In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 32, no 6, p. 611-613Article in journal (Refereed)
    Abstract [en]

    Simplified versions of the communication modes in the Fresnel domain are derived when the system apertures are large. The approximate modes, which are in the form of spherical waves and sinc functions with a spherical curvature, give physical insight into the communication modes approach and the basic limits of free-space optical communication systems. They also show that Gabor's information theory is readily derived from the communication modes.

  • 16.
    Burvall, Anna
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Martinsson, Per
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Friberg, Ari T.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Communication modes in axicon imaging2004In: Riao/Optilas 2004: 5th Iberoamerican Meeting On Optics And 8th Latin American Meeting On Optics, Lasers, And Their Applications, Pts 1-3: Ico Regional Meeting / [ed] Marcano, A; Paz, JL, 2004, Vol. 5622, p. 1133-1137Conference paper (Refereed)
    Abstract [en]

    The communication modes are an increasingly frequently used technique for studying the radiation, propagation, and scattering of light. The method is unusual in the way that it gives the information content and the resolution of the fields. It also allows for the possibility of including the noise considerations in the calculations. We present a brief summary of the communication modes method, together with our latest contribution: the communication modes for the axicon geometry.

  • 17.
    Burvall, Anna
    et al.
    National University of Ireland, Galway.
    Smith, Arlene
    National University of Ireland, Galway.
    Dainty, Christopher
    National University of Ireland, Galway.
    Elementary functions: Propagation of partially coherent light2009In: Journal of the Optical Society of America A, ISSN 0740-3232, Vol. 26, no 7, p. 1721-1729Article in journal (Refereed)
    Abstract [en]

    The theory of propagation of partially coherent light is well known, but performing numerical calculations still presents a difficulty because of the dimensionality of the problem. We propose using a recently introduced method based on the use of elementary functions [Wald et al. Proc. SPIE6040, 59621G (2005)] to reduce the integrals to two dimensions. We formalize the method, describe its inherent assumptions and approximations, and introduce a sampling criterion for adequate interpolation. We present an analysis of some special cases, such as the Gaussian Schell-model beam, and briefly discuss generalized numerical propagation of two-dimensional field distributions.

  • 18.
    Goncharov, Alexander
    et al.
    National University of Ireland, Galway.
    Burvall, Anna
    National University of Ireland, Galway.
    Dainty, Christopher
    National university of Ireland, Galway.
    Systematic design of anastigmatic lens axicon2007In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 46, no 24, p. 6076-6080Article in journal (Refereed)
    Abstract [en]

    We present an analytical method for systematic optical design of a double-pass axicon that shows almost no astigmatism in oblique illumination compared to a conventional linear axicon. The anastigmatic axicon is a singlet lens with nearly concentric spherical surfaces applied in double pass, making it possible to form a long narrow focal line of uniform width. The front and the back surfaces have reflective coatings in the central and annular zones, respectively, to provide the double pass. Our design method finds the radii of curvatures and axial thickness of the lens for a given angle between the exiting rays and the optical axis. It also finds the optimal position of the reflecting zones for minimal vignetting. This method is based on ray tracing of the real rays at the marginal heights of the aperture and therefore is superior to any paraxial method. We illustrate the efficiency of the method by designing a test axicon with optical parameters used for a prototype axicon, which was manufactured and experimentally tested. We compare the optical characteristics of our test axicon with those of the experimental prototype.

  • 19.
    Häggmark, Ilian
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vågberg, William
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Biomedical Applications of Multi-Material Phase Retrieval in Propagation-Based Phase-Contrast Imaging2018In: Microscopy and Microanalysis, Cambridge University Press, 2018, Vol. 24, p. 370-371Conference paper (Refereed)
  • 20. Jaroszewicz, Z.
    et al.
    Climent, V.
    Duran, V.
    Lancis, J.
    Kolodziejczyk, A.
    Burvall, Anna
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Friberg, Ari T.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Programmable axicon for variable inclination of the focal segment2004In: Journal of Modern Optics, ISSN 0950-0340, E-ISSN 1362-3044, Vol. 51, no 14, p. 2185-2190Article in journal (Refereed)
    Abstract [en]

    An axicon creates a long and narrow focal segment along its optical axis and therefore it is widely recognized as a cornerstone element in metrology and alignment techniques. In oblique incidence the shape of the axicon can be designed such that its sharp focal line is retained. However, when an elliptical or circular axicon is illuminated at an angle different from the nominal angle, the focal segment suffers from astigmatism and broadens significantly. The use of a spatial light modulator is proposed for real-time compensation of the ensuing aberration. The result is a diffractive axicon with its degree of ellipticity adjusted to the inclination angle of the incident light, thus producing a diffraction-limited Bessel beam for a wide range of illumination angles.

  • 21.
    Jaroszewicz, Zbigniew
    et al.
    Institute of Applied Optics, Warsaw.
    Burvall, Anna
    National university of Ireland, Galway.
    Friberg, Ari
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Garcia-Sucerquia, Jorge Ivan
    Kolodziejkzyk, Andrzej
    Nowakowski, Arkadiusz
    Focal segments obtained by interference of multiple Bessel beams: experimental results2004In: PHOTON MANAGEMENT  : PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE), vol 5456 / [ed] Frank Wyrowsky, SPIE , 2004, p. 484-489Conference paper (Other academic)
    Abstract [en]

    In the present communicate the experimental results are shown, which deal with the interference pattern created by superposition of multiple Bessel beams. They confirm our earlier results obtained analytically as well as by simulations. The interfering Bessel beams were obtained in a standard way, i.e., a field produced by a set of concentric annular apertures of narrow width illuminated by a plane wave was transformed by a lens into a set of Bessel beams.

  • 22.
    Jaroszewicz, Zbigniew
    et al.
    Institute of Applied Optics, Warsaw.
    Burvall, Anna
    National university of Ireland, Galway.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Axicon:  the most important optical element2005In: Optics and photonics news (Print), ISSN 1047-6938, E-ISSN 1541-3721, Vol. 16, no 4, p. 34-39Article in journal (Refereed)
    Abstract [en]

    Last year, the optics community celebrated the 50th anniversary of the formal naming of the axicon. Long before that, however, axicons generated vivid discussions and disagreements, often of fundamental importance to our understanding of optics.

  • 23.
    Jaroszewicz, Zbigniew
    et al.
    Institute of Applied Optics, Warsaw.
    Burvall, Anna
    National University of Ireland, Galway.
    Goncharov, Alexander
    National University of Ireland, Galway.
    Kolacz, Katarzyna
    Institute of Applied Optics, Warsaw.
    Spheric long-focal-depth lens: a comment2008In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 281, no 19, p. 4849-4850Article in journal (Refereed)
  • 24.
    Kolacz, Katarzyna
    et al.
    Institute of applied optics, Warsaw.
    Burvall, Anna
    National University of Ireland, Galway.
    Goncharov, Alexander
    National University of Galway, Ireland.
    Jaroszewicz, Zbigniew
    Insitute of Applied Optics, Warsaw.
    Dainty, Christopher
    National University of Ireland, Galway.
    Friberg, Ari
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Present design of lens axicons and their history2007In: Photonics Applications In Astronomy, Communications, Industry, And High-Energy Physics Experiments 2007, Pts 1 And 2 / [ed] Ryszard S. Romaniuk, SPIE - International Society for Optical Engineering, 2007, p. 693740-Conference paper (Refereed)
    Abstract [en]

    Lens systems designed to work like axicons can be a simple and cheap way of generating focal lines characteristic for these elements. We present two lens axicons made from ordinary lenses with spherical surfaces which take advantage of their inherent spherical aberration for creation of the focal segment. One of them is composed from two lenses with blocked central part. The second one is a single meniscus lens with appropriate reflective coatings. The results show that both new elements exhibit main axicon properties. Additionally the second lens axicon is resistant to astigmatism and maintains good quality of the focal segment even in the case of oblique illumination.

  • 25.
    Larsson, Daniel H.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Westermark, U.
    Takman, Per
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Arsenian Henriksson, M.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Small-animal tomography with a liquid-metal-jet x-ray source2012In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE, SPIE - International Society for Optical Engineering, 2012, Vol. 8313, p. 83130N-Conference paper (Refereed)
    Abstract [en]

    X-ray tomography of small animals is an important tool for medical research. For high-resolution x-ray imaging of few-cm-thick samples such as, e.g., mice, high-brightness x-ray sources with energies in the few-10-keV range are required. In this paper we perform the first small-animal imaging and tomography experiments using liquid-metal-jet-anode x-ray sources. This type of source shows promise to increase the brightness of microfocus x-ray systems, but present sources are typically optimized for an energy of 9 keV. Here we describe the details of a high-brightness 24-keV electron-impact laboratory microfocus x-ray source based on continuous operation of a heated liquid-In/Ga-jet anode. The source normally operates with 40 W of electron-beam power focused onto the metal jet, producing a 7×7 μm 2 FWHM x-ray spot. The peak spectral brightness is 4 × 10 9 photons/( s × mm 2 × mrad 2 × 0.1%BW) at the 24.2 keV In K α line. We use the new In/Ga source and an existing Ga/In/Sn source for high-resolution imaging and tomography of mice.

  • 26.
    Larsson, Daniel H.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Westermark, Ulrica K.
    Arsenian Henriksson, Marie
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    First application of liquid-metal-jet sources for small-animal imaging: High-resolution CT and phase-contrast tumor demarcation2013In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 40, no 2, p. 021909-Article in journal (Refereed)
    Abstract [en]

    Purpose: Small-animal studies require images with high spatial resolution and high contrast due to the small scale of the structures. X-ray imaging systems for small animals are often limited by the microfocus source. Here, the authors investigate the applicability of liquid-metal-jet x-ray sources for such high-resolution small-animal imaging, both in tomography based on absorption and in soft-tissue tumor imaging based on in-line phase contrast. Methods: The experimental arrangement consists of a liquid-metal-jet x-ray source, the small-animal object on a rotating stage, and an imaging detector. The source-to-object and object-to-detector distances are adjusted for the preferred contrast mechanism. Two different liquid-metal-jet sources are used, one circulating a Ga/In/Sn alloy and the other an In/Ga alloy for higher penetration through thick tissue. Both sources are operated at 40-50 W electron-beam power with similar to 7 mu m x-ray spots, providing high spatial resolution in absorption imaging and high spatial coherence for the phase-contrast imaging. Results: High-resolution absorption imaging is demonstrated on mice with CT, showing 50 mu m bone details in the reconstructed slices. High-resolution phase-contrast soft-tissue imaging shows clear demarcation of mm-sized tumors at much lower dose than is required in absorption. Conclusions: This is the first application of liquid-metal-jet x-ray sources for whole-body small-animal x-ray imaging. In absorption, the method allows high-resolution tomographic skeletal imaging with potential for significantly shorter exposure times due to the power scalability of liquid-metal-jet sources. In phase contrast, the authors use a simple in-line arrangement to show distinct tumor demarcation of few-mm-sized tumors. This is, to their knowledge, the first small-animal tumor visualization with a laboratory phase-contrast system.

  • 27.
    Larsson, Daniel H.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Takman, Per A.C.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    A 24 keV liquid-metal-jet x-ray source for biomedical applications2011In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 82, no 12, p. 123701-Article in journal (Refereed)
    Abstract [en]

    We present a high-brightness 24-keV electron-impact microfocus x-ray source based on continuous operation of a heated liquid-indium/gallium-jet anode. The 30–70 W electron beam is magnetically focused onto the jet, producing a circular 7–13 μm full width half maximum x-ray spot. The measured spectral brightness at the 24.2 keV In Kα line is 3 × 109 photons/(s × mm2 × mrad2 × 0.1% BW) at 30 W electron-beam power. The high photon energy compared to existing liquid-metal-jet sources increases the penetration depth and allows imaging of thicker samples. The applicability of the source in the biomedical field is demonstrated by high-resolution imaging of a mammography phantom and a phase-contrast angiography phantom.

  • 28.
    Lundström, Ulf
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Scott, L.
    Westermark, U. K.
    Wilhelm, M.
    Henriksson, M. Arsenian
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    X-ray phase-contrast CO2 angiography for sub-10 mu m vessel imaging2012In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 57, no 22, p. 7431-7441Article in journal (Refereed)
    Abstract [en]

    X-ray in-line phase contrast has recently been combined with CO2 angiography for high-resolution small-animal vascular imaging at low radiation dose. In this paper we further investigate the potential and limitations of this method and demonstrate observation of vessels down to 8 mu m in diameter, considerably smaller than the 60 mu m previously reported. Our in-line phase-contrast imaging system is based on a liquid-metal-jet-anode x-ray source and utilizes free-space propagation to convert phase shifts, caused by refractive index variations, into intensity differences. Enhanced refractive index variations are obtained through injection of CO2 gas into the vascular system to replace the blood. We show rat-kidney images with blood vessels down to 27 mu m in diameter and mouse-ear images with vessels down to 8 mu m. The minimum size of observable blood vessels is found to be limited by the penetration of gas into the vascular system and the signal-to-noise ratio, i.e. the allowed dose. The diameters of vessels being gas-filled depend on the gas pressure and follow a simple model based on surface tension. A theoretical signal-to-noise comparison shows that this method requires 1000 times less radiation dose than conventional iodine-based absorption contrast for observing sub-50 mu m vessels.

  • 29.
    Lundström, Ulf
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Takman, Per A. C.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Scott, L.
    Brismar, H.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    X-ray phase contrast for CO2 microangiography2012In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 57, no 9, p. 2603-2617Article in journal (Refereed)
    Abstract [en]

    We demonstrate a laboratory method for imaging small blood vessels using x-ray propagation-based phase-contrast imaging and carbon dioxide (CO2) gas as a contrast agent. The limited radiation dose in combination with CO2 being clinically acceptable makes the method promising for small-diameter vascular visualization. We investigate the possibilities and limitations of the method for small-animal angiography and compare it with conventional absorption-based x-ray angiography. Photon noise in absorption-contrast imaging prevents visualization of blood vessels narrower than 50 mu m at the highest radiation doses compatible with living animals, whereas our simulations and experiments indicate the possibility of visualizing 20 mu m vessels at radiation doses as low as 100 mGy. Experimental computed tomography of excised rat kidney shows blood vessels of diameters down to 60 mu m with improved image quality compared to absorption-based methods. With our present prototype x-ray source, the acquisition time for a tomographic dataset is approximately 1 h, which is long compared to the 1-20 min common for absorption-contrast micro-CT systems. Further development of the liquid-metal-jet microfocus x-ray sources used here and high-resolution x-ray detectors shows promise to reduce exposure times and make this high-resolution method practical for imaging of living animals.

  • 30.
    Lundström, Ulf
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Takman, Per
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Scott, L.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    X-ray phase contrast angiography using CO 2 as contrast agent2012In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE, SPIE - International Society for Optical Engineering, 2012, Vol. 8313, p. 83135J-Conference paper (Refereed)
    Abstract [en]

    We investigate the possibility of using x-ray in-line phase-contrast imaging with gaseous carbon dioxide as contrast agent to visualize small blood vessels. These are difficult to image at reasonable radiation doses using the absorption of conventional iodinated contrast agents. In-line phase contrast is a method for retrieving information on the electron density of the sample as well as the absorption, by moving the detector away from the sample to let phase variations in the transmitted x-rays develop into intensity variations at the detector. Blood vessels are normally difficult to observe in phase contrast even with iodinated contrast agents as the density difference compared to most tissues is small. Carbon dioxide is a clinically accepted x-ray contrast agent. The gas is injected into the blood stream of patients to temporarily displace the blood in a region and thereby reduce the x-ray absorption in the blood vessels. This gives a large density difference which is ideal for phase-contrast imaging. We demonstrate the possibilities of the method by imaging the arterial system of a rat kidney injected with carbon dioxide. Vessels down to 23 ÎŒm in diameter are shown. The method shows potential for live small-animal imaging.

  • 31.
    Lundström, Ulf
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Westermark, U. K.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Small-Animal microangiography using phase-contrast X-ray imaging and gas as contrast agent2014In: Medical Imaging 2014: Physics of Medical Imaging, SPIE - International Society for Optical Engineering, 2014, p. 90331L-Conference paper (Refereed)
    Abstract [en]

    We use propagation-based phase-contrast X-ray imaging with gas as contrast agent To visualize The microvasculature in small animals like mice and rats. The radiation dose required for absorption X-ray imaging is proportional To The minus fourth power of The structure size To be detected. This makes small vessels impossible To image at reasonable radiation doses using The absorption of conventional iodinated contrast agents. Propagation-based phase contrast gives enhanced contrast for high spatial frequencies by moving The detector away from The sample To let phase variations in The Transmitted X-rays develop into intensity variations at The detector. Blood vessels are normally difficult To observe in phase contrast even with iodinated contrast agents as The density difference between blood and most Tissues is relatively small. By injecting gas into The blood stream This density difference can be greatly enhanced giving strong phase contrast. One possible gas To use is carbon dioxide, which is a clinically accepted X-ray contrast agent. The gas is injected into The blood stream of patients To Temporarily displace The blood in a region and Thereby reduce The X-ray absorption in The blood vessels. We have shown That This method can be used To image blood vessels down To 8 μm in diameter in mouse ears. The low dose requirements of This method indicate a potential for live small-Animal imaging and longitudinal studies of angiogenesis.

  • 32.
    Lundström, Ulf
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Westermark, Ulrica K.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Arsenian Henriksson, Marie
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    X-ray phase contrast with injected gas for tumor microangiography2014In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 59, no 11, p. 2801-2811Article in journal (Refereed)
    Abstract [en]

    We show that the microvasculature of mouse tumors can be visualized using propagation-based phase-contrast x-ray imaging with gas as the contrast agent. The large density difference over the gas-tissue interface provides high contrast, allowing the imaging of small-diameter blood vessels with relatively short exposure times and low dose using a compact liquid-metal-jet x-ray source. The method investigated is applied to tumors (E1A/Ras-transformed mouse embryonic fibroblasts) grown in mouse ears, demonstrating sub-15-mu m-diameter imaging of their blood vessels. The exposure time for a 2D projection image is a few seconds and a full tomographic 3D map takes some minutes. The method relies on the strength of the vasculature to withstand the gas pressure. Given that tumor vessels are known to be more fragile than normal vessels, we investigate the tolerance of the vasculature of 12 tumors to gas injection and find that a majority withstand 200 mbar pressures, enough to fill 12-mu m-diameter vessels with gas. A comparison of the elasticity of tumorous and non-tumorous vessels supports the assumption of tumor vessels being more fragile. Finally, we conclude that the method has the potential to be extended to the imaging of 15 mu m vessels in thick tissue, including mouse imaging, making it of interest for, e.g., angiogenesis research.

  • 33.
    Martinsson, Per
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Ma, Ping
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Burvall, Anna
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Communication modes in scalar diffraction2008In: Optik (Stuttgart), ISSN 0030-4026, E-ISSN 1618-1336, Vol. 119, no 3, p. 103-111Article in journal (Refereed)
    Abstract [en]

    The communication modes are a useful concept in studies of optical resolution, wave propagation, and image synthesis. We present an overview of earlier results on the communication modes in scalar diffraction theory. Besides the general theory, the modes are reviewed for the far-field and Fresnel regimes, and new eigenequations are derived for wide-angle diffraction. We prove a conjugate relationship between the transmitting and receiving modes in a general symmetric system. We also suggest an approximate method for far-field and Fresnel domain propagation, in which propagation amounts to a rotation of each mode in the complex plane. The main focus is on the near-field communication modes, where we present numerical examples of the modes and coupling strengths for a near-field geometry with a sub-wavelength size receiving domain. These results provide insights, for example, into the understanding of near-field scanning probe techniques.

  • 34.
    Reza, S.
    et al.
    KTH, School of Engineering Sciences (SCI).
    Zhou, Tunhe
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lindgren, J.
    Fröjdh, C.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Norlin, B.
    Phase-contrast X-ray imaging for non-destructivequality inspections of paperboardsManuscript (preprint) (Other academic)
  • 35.
    Smith, Arlene
    et al.
    National University of Ireland, Galway.
    Burvall, Anna
    National University of Ireland, Galway.
    Dainty, Christopher
    National University of Ireland, Galway.
    Numerical partially coherent imaging using elementary functions2008In: OPTICAL DESIGN AND ENGINEERING III, PTS 1 AND 2 / [ed] Laurent Mazuray; Rolf Wartmann; Andrew Wood; Jean-Luc Tissot; Jeffrey M. Raynor, SPIE - International Society for Optical Engineering, 2008Conference paper (Refereed)
    Abstract [en]

    The theory of coherence and propagation of light through imaging systems is well established. For coherent and incoherent sources, the intensity in the image plane can be predicted numerically using a straightforward convolution calculation. Image formation becomes more complicated when dealing with partially coherent light, as treating two-dimensional intensity fields (described by the four-dimensional mutual coherence function in the time domain or the cross-spectral density in the frequency domain) requires evaluating four-dimensional integrals. Thus, calculations are complex, slow to process and place demands on system memory. We present a variation of a method recently introduced [Wald et al, Proc SPIE, 59621G, 2005], in which elementary functions are used to reduce the integrals to two dimensions for light of relatively high degree of coherence. The method resembles the coherent-mode expansion, but the elementary functions are easier to find and work with than the coherent modes. We outline the method and present some numerical results. This approach has applications in modelling of photolithographic systems in which partially coherent excimer lasers operating in the Deep Ultra-Violet (DUV) regime have been used for the last decade. An accurate numerical model of such systems could prove useful in solving the classic inverse imaging problem of lithography reticle design.

  • 36.
    Smith, Arlene
    et al.
    National university of Ireland, Galway.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Dainty, Christopher
    National University of Ireland, Galway.
    Partial spatial coherence in an excimer-laser lithographic imaging system2010In: OPTICAL MICROLITHOGRAPHY XXIII / [ed] Mircea V. Dusa; Will Conley, SPIE - International Society for Optical Engineering, 2010Conference paper (Refereed)
    Abstract [en]

    We have recently explored the Elementary Function method, previously presented by Wald et al (Proc. SPIE 59621G, 2005), and we have demonstrated under what circumstances this method can be used to reduce the propagation calculations of partially coherent light to two dimensions. In this paper, we examine the methods used to measure the spatial coherence of a light source in the literature. We present a method based on work previously shown by Mejia et al (Opt Comm 273 (428-434), 2007) which uses an array of pinholes with one degree of redundancy. We discuss the design of the pinhole array and present the results of some simulations.

  • 37.
    Smith, Arlene
    et al.
    National University of Irelend, Galway.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Dainty, Christopher
    National University of Ireland, Galway.
    Partially coherent image computation using elementary functions2009In: Optical Microlithography XXII / [ed] Harry J. Levinson; Mircea V. Dusa, SPIE - International Society for Optical Engineering, 2009Conference paper (Other academic)
    Abstract [en]

    It is well-known that calculations of the propagation of partially coherent light, such as those required for the calculation of two-dimensional image intensities, involve four-dimensional functions. Recently, Wald et al [Proc SPIE, 59621G, 2005] outlined a method for reducing the four-dimensional problem to a purely twodimensional one. Instead of an exact modal expansion of the mutual coherence function or cross-spectral density, an approximate expansion is used, into what we call elementary functions. In this paper, rules of thumb are developed for fast and efficient computation of the image intensity in a simple partially coherent lithographic imaging system.

  • 38.
    Thaning, Anna
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Asymptotic methods in design and characterization ofdiffractive axicons2002Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This thesis addresses the subject of diffractive axicons inpartially coherent or oblique illumination. Design andcharacterization of the axicons are performed using asymptoticwave optics, employing the stationary-phase method to obtainapproximations of the diffraction integrals.

    A design method for axicons in partially coherentillumination is derived. The method can be applied to anyincident illumination on radially symmetric Schell-model form.It provides analytical solutions for some specific cases, butfor most incident intensity and coherence distributions it canbe solved numerically to yield the desired on-axis intensity.In addition, a method for estimating the width of the focalline is provided. For coherent light, the design method isidentical to the old one based on energy conservation in raybundles. Since the new method is derived entirely from waveoptics, it both clarifies the old method and extends it topartially coherent light.

    Oblique illumination of axicons, frequently encountered inapplications, causes degradation of the focal line. This changeis characterized, and from the asymptotic theory it is foundthat the focal line is described by an asteroid curve. Thewidth of the focal segment in oblique illumination isaccurately predicted, as confirmed by simulations andexperiments. It is also found that at a fixed angle, anelliptical axicon may be used to compensate for the adverseeffects of oblique illumination.

    Keywords:axicons, diffractive optics, coherence,asymptotic methods

  • 39.
    Thaning, Anna
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Friberg, Ari T.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Transverse variation of partially coherent axicon lines2002In: Journal of Modern Optics, ISSN 0950-0340, E-ISSN 1362-3044, Vol. 49, no 11, p. 1933-1941Article in journal (Refereed)
    Abstract [en]

    Diffractive axicons operating in spatially partially coherent light can be designed non-iteratively, on the basis of asymptotic wave theory, to produce focal lines with prescribed on-axis intensity profiles. In this paper we analyse the transverse intensity variation of these axicon lines, concentrating on relatively coherent beams. By Taylor expansion, a way is found to approximate the transverse intensity profile, without the demanding numerical integration otherwise needed. From this expression, also the width of the focal line as a function of position on the optical axis can be easily found. As now both this width profile and the on-axis intensity profile can be determined, the two most important features of the partially coherent axicon focal line have been characterized.

  • 40.
    Thaning, Anna
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Friberg, Ari T.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Jaroszewicz, Z.
    Synthesis of diffractive axicons for partially coherent light based on asymptotic wave theory2001In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 26, no 21, p. 1648-1650Article in journal (Refereed)
    Abstract [en]

    A general, noniterative method for designing diffractive axicons is derived. This new technique clarifies the earlier phenomenological design principle that was used for coherent light and extends it to the domain of partial coherence. The approach is based on the method of stationary phase in fluctuating diffracted wave fields, and it applies to arbitrary axially symmetric radiation of the Schell-model type. It is shown that the general design equation can be solved numerically, in a straightforward way, for any reasonable illumination and image specifications.

  • 41.
    Thaning, Anna
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Martinsson, Per
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Karelin, Mikalai
    Friberg, Ari
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Limits of diffractive optics by communication modes2003In: Journal of Optics. A, Pure and applied optics, ISSN 1464-4258, E-ISSN 1741-3567, Vol. 5, p. 153-158Article in journal (Refereed)
    Abstract [en]

    We apply the concept of communication modes, previously employed in information theory, to diffractive optics. The communication modes are used to study the resolution of one-dimensional optical systems in the Fresnel regime. Using the modes, which in this geometry are prolate spheroidal wavefunctions, the best achievable approximation to a given target field can be assessed. In this paper, the field propagation in terms of the communication modes is demonstrated numerically, and the results on resolution are confirmed by Fourier analysis.

  • 42. Thuering, T.
    et al.
    Zhou, Tunhe
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Rutishauser, S.
    David, C.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Stampanoni, M.
    X-ray grating interferometry with a liquid-metal-jet source2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, no 9, p. 091105-Article in journal (Refereed)
    Abstract [en]

    A liquid-metal-jet X-ray tube is used in an X-ray phase-contrast microscope based on a Talbot type grating interferometer. With a focal spot size in the range of a few microns and a photon flux of similar to 10(12) photons/s x sr, the brightness of such a source is approximately one order of magnitude higher than for a conventional microfocus source. For comparison, a standard microfocus source was used with the same grating interferometer, showing significantly increased visibility for the liquid-metal-jet arrangement. Together with the increased flux, this results in improved signal-to-noise ratio.

  • 43. Zanette, I.
    et al.
    Zdora, M. -C
    Zhou, Tunhe
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Thibault, P.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Pfeiffer, F.
    X-ray microtomography using correlation of near-field speckles for material characterization2015In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 112, no 41, p. 12569-12573Article in journal (Refereed)
    Abstract [en]

    Nondestructive microscale investigation of objects is an invaluable tool in life and materials sciences. Currently, such investigation is mainly performed with X-ray laboratory systems, which are based on absorption-contrast imaging and cannot access the information carried by the phase of the X-ray waves. The phase signal is, nevertheless, of great value in X-ray imaging as it is complementary to the absorption information and in general more sensitive to visualize features with small density differences. Synchrotron facilities, which deliver a beam of high brilliance and high coherence, provide the ideal condition to develop such advanced phase-sensitive methods, but their access is limited. Here we show how a small modification of a laboratory setup yields simultaneously quantitative and 3D absorption and phase images of the object. This single-shot method is based on correlation of X-ray near-field speckles and represents a significant broadening of the capabilities of laboratory- based X-ray tomography.

  • 44. Zanette, I.
    et al.
    Zhou, Tunhe
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Zdora, M.
    Thibault, P.
    Pfeiffer, F.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Speckle-Based X-Ray Phase-Contrast and Dark-Field Imaging with a Laboratory Source2014In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 112, no 25, p. 253903-Article in journal (Refereed)
    Abstract [en]

    We report on the observation and application of near-field speckles with a laboratory x-ray source. The detection of speckles is possible thanks to the enhanced brilliance properties of the used liquid-metal-jet source, and opens the way to a range of new applications in laboratory-based coherent x-ray imaging. Here, we use the speckle pattern for multimodal imaging of demonstrator objects. Moreover, we introduce algorithms for phase and dark-field imaging using speckle tracking, and we show that they yield superior results with respect to existing methods.

  • 45.
    Zhou, Tunhe
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Low-dose phase-contrast X-ray imaging: a comparison of two methods2013In: 11th International Conference On X-Ray Microscopy (XRM2012), Institute of Physics (IOP), 2013, p. 012041-Conference paper (Refereed)
    Abstract [en]

    Propagation- and grating-based X-ray phase-contrast imaging methods are compared theoretically. As a prospective application of phase-contrast methods in medical or small animal imaging, carbon dioxide (CO2) angiography is the simulated task. The required dose for the observable blood vessel is compared through simulation. The result indicates that the propagation-based method requires lower dose in this application.

  • 46.
    Zhou, Tunhe
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Thüring, T.
    Rutishauser, S.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Stampanoni, M.
    David, C.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Comparison of propagation-and grating-based x-ray phase-contrast imaging techniques with a liquid-metal-jet source2014In: Medical Imaging 2014: Physics of Medical Imaging, SPIE - International Society for Optical Engineering, 2014, p. 903353-Conference paper (Refereed)
    Abstract [en]

    X-ray phase-contrast imaging has been developed as an alternative to conventional absorption imaging, partly for its dose advantage over absorption imaging at high resolution. Grating-based imaging (GBI) and propagation-based imaging (PBI) are two phase-contrast techniques used with polychromatic laboratory sources. We compare the two methods by experiments and simulations with respect to required dose. A simulation method based on the projection approximation is designed and verified with experiments. A comparison based on simulations of the doses required for detection of an object with respect to its diameter is presented, showing that for monochromatic radiation, there is a dose advantage for PBI for small features but an advantage for GBI at larger features. However, GBI suffers more from the introduction of polychromatic radiation, in this case so much that PBI gives lower dose for all investigated feature sizes. Furthermore, we present and compare experimental images of biomedical samples. While those support the dose advantage of PBI, they also highlight the GBI advantage of quantitative reconstruction of multimaterial samples. For all experiments a liquid-metal-jet source was used. Liquid-metal-jet sources are a promising option for laboratory-based phase-contrast imaging due to the relatively high brightness and small spot size.

  • 47.
    Zhou, Tunhe
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Thüring, Thomas
    Rutishauser, Simon
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Stampanoni, M.
    David, C.
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Comparison of two x-ray phase-contrast imaging methods with a microfocus source2013In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 21, no 25, p. 30183-30195Article in journal (Refereed)
    Abstract [en]

    We present a comparison for high-resolution imaging with a laboratory source between grating-based (GBI) and propagation-based (PBI) x-ray phase-contrast imaging. The comparison is done through simulations and experiments using a liquid-metal-jet x-ray microfocus source. Radiation doses required for detection in projection images are simulated as a function of the diameter of a cylindrical sample. Using monochromatic radiation, simulations show a lower dose requirement for PBI for small object features and a lower dose for GBI for larger object features. Using polychromatic radiation, such as that from a laboratory microfocus source, experiments and simulations show a lower dose requirement for PBI for a large range of feature sizes. Tested on a biological sample, GBI shows higher noise levels than PBI, but its advantage of quantitative refractive index reconstruction for multi-material samples becomes apparent.

  • 48.
    Zhou, Tunhe
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Zanette, Irene
    Zdora, Marie-Christine
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. Stanford Univ, Dept Biol Struct, Stanford, CA 94305 USA.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Pfeiffer, Franz
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Speckle-based x-ray phase-contrast imaging with a laboratory source and the scanning technique2015In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 40, no 12, p. 2822-2825Article in journal (Refereed)
    Abstract [en]

    The speckle-based scanning method for x-ray phase-contrast imaging is implemented with a liquid-metal-jet source. Using the two-dimensional scanning technique, the phase shift introduced by the object is retrieved in both transverse orientations, and the limitations on spatial resolution inherent to the speckle-tracking technique are avoided. This method opens up possibilities of new high-resolution multimodal applications for lab-based phasecontrast x-ray imaging.

  • 49.
    Zhou, Tunhe
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Zdora, Marie-Christine
    Zanette, Irene
    Romell, Jenny
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Noise analysis of speckle-based x-ray phase-contrast imaging2016In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 41, no 23, p. 5490-5493Article in journal (Refereed)
    Abstract [en]

    Speckle-based x-ray phase-contrast imaging has drawn increasing interest in recent years as a simple, multimodal, cost-efficient, and laboratory-source adaptable method. We investigate its noise properties to help further optimization on the method and further comparison with other phase-contrast methods. An analytical model for assessing noise in a differential phase signal is adapted from studies on the digital image correlation technique in experimental mechanics and is supported by simulations and experiments. The model indicates that the noise of the differential phase signal from speckle-based imaging has a behavior similar to that of the grating-based method.

  • 50.
    Zhou, Tunhe
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Zdora, M.-C.
    Zanette, I.
    Romell, J.
    Hertz, H. M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Noise analysis of speckle-based x-ray phase-contrast imagingManuscript (preprint) (Other academic)
1 - 50 of 50
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