Progress in High-Resolution X-Ray Holographic Microscopy

Jacobsen, Chris; Kirz, Janos; McQuaid, Kenneth R.; Rothman, Stephen; Feder, R.; Sayre, D.

doi:10.1007/978-3-540-39246-0_44

Cited by 14 publications

(7 citation statements)

References 17 publications

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“…The number of steps N, namely the number of times that the ray is refracted, is proportional to the thickness of the screen L. The average angle of refraction is zero, but its standard deviation is proportional to σ n and thus to λ 2 . As a result we expect α RP S ∝ σ n √ N ∝ λ 2 √ L, as in expression (19).…”

Section: Destroying Spurious Phase Images On X-ray Topographsmentioning

confidence: 69%

“…For the images described above, the size of the first Fresnel zone varies from 0 to typically 8 µm, therefore it is most often smaller than or comparable with the characteristic size of the object. This explains why the image looks more like a direct image of the contours of the object, in which each border is imaged independently, rather than like a hologram, although the experimental setup is the same as for in-line Gabor holography [19].…”

Section: Basic Elements Of the Imaging Processmentioning

confidence: 99%

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Phase objects in synchrotron radiation hard x-ray imaging

Cloetens

Barrett

Baruchel

et al. 1996

J. Phys. D: Appl. Phys.

807

506

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Phase objects are readily imaged through Fresnel diffraction in the hard x-ray beams of third-generation synchrotron radiation sources such as the ESRF, due essentially to the very small angular size of the source. Phase objects can lead to spurious contrast in x-ray diffraction images (topographs) of crystals. It is shown that this contrast can be eliminated through random phase plates, which provide an effective way of tailoring the angular size of the source. The possibilities of this very simple technique for imaging phase objects in the hard x-ray range are explored experimentally and discussed. They appear very promising, as shown in particular by the example of a piece of human vertebra, and could be extended to phase tomography.

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Section: Destroying Spurious Phase Images On X-ray Topographsmentioning

confidence: 69%

Section: Basic Elements Of the Imaging Processmentioning

confidence: 99%

Phase objects in synchrotron radiation hard x-ray imaging

Cloetens

Barrett

Baruchel

et al. 1996

J. Phys. D: Appl. Phys.

807

506

View full text Add to dashboard Cite

show abstract

“…16 Soon after the introduction of holography 17 by Gabor in 1948, the possibility of x-ray holography was explored, 18 and interest has continued, mainly in the context of soft x-ray microscopy. [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] As is well known, the hologram contains phase information from the object wave field, so that it may be considered in a sense as a phase-contrast image, i.e., the phase has been ''made visible,'' although a reconstruction step is required to reproduce the phase distribution at the object. From a different viewpoint, the reconstruction may be considered as a form of phase retrieval.…”

Section: Introductionmentioning

confidence: 99%

Contrast and resolution in imaging with a microfocus x-ray source

Pogany

Gao

Wilkins

1997

Review of Scientific Instruments

442

292

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A simple general treatment of x-ray image formation by Fresnel diffraction is presented; the image can alternatively be considered as an in-line hologram. Particular consideration is given to phase-contrast microscopy and imaging using hard x rays. The theory makes use of the optical transfer function in a similar way to that used in the theory of electron microscope imaging. Resolution and contrast are the criteria used to specify the visibility of an image. Resolution in turn depends primarily on the spatial coherence of the illumination, with chromatic coherence of lesser importance. Thus broadband microfocus sources can give useful phase-contrast images. Both planeand spherical-wave conditions are explicitly considered as limiting cases appropriate to macroscopic imaging and microscopy, respectively, while intermediate cases may also be of practical interest. Some results are presented for x-ray images showing phase contrast.

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“…The wave leaving the sample u(x) is in this case simply obtained as the multiplication of the incident wave u1(x) with the transmission function: (4) To describe propagation over a fmite distance d we will use the diffraction integral in the usual approximation of Fresnel diffraction'5. The wave u-(x) is then the convolution of u0(x) with the kernel Pj(x) = (iAd)112 exp (ut x2 I Ad) (5) In reciprocal space propagation over a distance d corresponds to a simple multiplication of the Fourier transform of the field with the propagator Pa(f) exp (-iicAdI) (6) wherefdenotes the spatial frequency conjugate to x.…”

Section: Methodsmentioning

confidence: 99%

<title>Quantitative aspects of coherent hard x-ray imaging: Talbot images and holographic reconstruction</title>

et al. 1997

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Free space propagation or Fresnel diffraction is an effective method to sense the phase modulation of hard X-ray beams. We use the variation with propagation distance d ofthe diffraction pattern both to study periodic objects and to handle the inverse problem, i.e. to extract information on the phase and amplitude of the transmitted wave from the intensity distribution in the defocused images. The 'Talbot effect', a special manifestation of Fresnel diffraction, implies that the intensity distribution of coherent light transmitted through a periodic object is periodic both in the direction of the object periodicity (period a) and in the propagation direction @eriod 2a2/A ) being the wavelength). We have performed a first investigation ofthe Talbot effect for hard X-rays (O.7A) on two phase gratings.Apart from a lateral shift of a12, identical intensity distributions are ideally expected in two recording planes a distance a2IA apart. Actually, a decrease ofcontrast occurs as a result ofthe partial coherence ofthe incident beam, providing a measure of the degree of coherence. Focus variation, as applied in transmission electron microscopy, consists in recording at different d a series of images which are combined through a suitable algorithm to reconstruct the wave function. The algorithm is briefly presented and is used to reconstruct the phase modulation introduced by a polymer fiber from the experimental data.

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Progress in High-Resolution X-Ray Holographic Microscopy

Cited by 14 publications

References 17 publications

Phase objects in synchrotron radiation hard x-ray imaging

Phase objects in synchrotron radiation hard x-ray imaging

Contrast and resolution in imaging with a microfocus x-ray source

<title>Quantitative aspects of coherent hard x-ray imaging: Talbot images and holographic reconstruction</title>

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