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Sample records for aberration-corrected z-contrast imaging

  1. Aberration-Corrected TEM Imaging of Oxygen Occupancy in YSZ.

    PubMed

    An, Jihwan; Koh, Ai Leen; Park, Joong Sun; Sinclair, Robert; Gür, Turgut M; Prinz, Fritz B

    2013-04-01

    We present atomic-scale imaging of oxygen columns and show quantitative analysis on the occupancy of the columns in yttria-stabilized zirconia (YSZ) using aberration-corrected TEM operated under the negative Cs condition. Also, individual contributions both from oxygen column occupancy and the static displacement of oxygen atoms due to occupancy change to the observed column intensities of TEM images were systematically investigated using HRTEM simulation. We found that oxygen column intensity is governed primarily by column occupancy rather than by static displacement of oxygen atoms. Utilizing the aberration-corrected TEM capability and HRTEM simulation results, we experimentally verified that oxygen vacancies segregate near the single grain boundary of a YSZ bicrystal. The methodology and the high spatial resolution characterization tool employed in the present study provide insights into the distribution of oxygen vacancies in the bulk as well as near grain boundaries and pave the way for further investigation and atomic-scale analysis in other important oxide materials.

  2. Z-Contrast Imaging in the Scanning Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Pennycook, S. J.; Jesson, D. E.; Chisholm, M. F.; Browning, N. D.; McGibbon, A. J.; McGibbon, M. M.

    1995-12-01

    Z-contrast STEM using an annular detector can provide an intuitively interpretable, column-by-column, compositional map of crystals. Incoherent imaging reduces dynamical effects to second order so that the map directly reflects the positions of the atomic columns and their relative high-angle scattering power. This article outlines how these characteristics arise, presents some examples of the insights available from a direct image, and discusses recent developments of atomic-resolution microanalysis, direct structure retrieval by maximum entropy analysis, and Z-contrast imaging at 1.4 [Angstrom capital A, ring] resolution using a 300-kV STEM.

  3. Lattice and strain analysis of atomic resolution Z-contrast images based on template matching.

    PubMed

    Zuo, Jian-Min; Shah, Amish B; Kim, Honggyu; Meng, Yifei; Gao, Wenpei; Rouviére, Jean-Luc

    2014-01-01

    A real space approach is developed based on template matching for quantitative lattice analysis using atomic resolution Z-contrast images. The method, called TeMA, uses the template of an atomic column, or a group of atomic columns, to transform the image into a lattice of correlation peaks. This is helped by using a local intensity adjusted correlation and by the design of templates. Lattice analysis is performed on the correlation peaks. A reference lattice is used to correct for scan noise and scan distortions in the recorded images. Using these methods, we demonstrate that a precision of few picometers is achievable in lattice measurement using aberration corrected Z-contrast images. For application, we apply the methods to strain analysis of a molecular beam epitaxy (MBE) grown LaMnO₃ and SrMnO₃ superlattice. The results show alternating epitaxial strain inside the superlattice and its variations across interfaces at the spatial resolution of a single perovskite unit cell. Our methods are general, model free and provide high spatial resolution for lattice analysis.

  4. Image transfer with spatial coherence for aberration corrected transmission electron microscopes.

    PubMed

    Hosokawa, Fumio; Sawada, Hidetaka; Shinkawa, Takao; Sannomiya, Takumi

    2016-08-01

    The formula of spatial coherence involving an aberration up to six-fold astigmatism is derived for aberration-corrected transmission electron microscopy. Transfer functions for linear imaging are calculated using the newly derived formula with several residual aberrations. Depending on the symmetry and origin of an aberration, the calculated transfer function shows characteristic symmetries. The aberrations that originate from the field's components, having uniformity along the z direction, namely, the n-fold astigmatism, show rotational symmetric damping of the coherence. The aberrations that originate from the field's derivatives with respect to z, such as coma, star, and three lobe, show non-rotational symmetric damping. It is confirmed that the odd-symmetric wave aberrations have influences on the attenuation of an image via spatial coherence. Examples of image simulations of haemoglobin and Si [211] are shown by using the spatial coherence for an aberration-corrected electron microscope.

  5. Quantitative Z-Contrast Imaging of Supported Metal Complexes and Clusters - A Gateway to Understanding Catalysis on the Atomic Scale

    SciTech Connect

    Browning, Nigel D.; Aydin, C.; Lu, Jing; Kulkarni, Apoorva; Okamoto, Norihiko L.; Ortalan, V.; Reed, Bryan W.; Uzun, Alper; Gates, Bruce C.

    2013-09-01

    Z-contrast imaging in an aberration-corrected scanning transmission electron microscope can be used to observe and quantify the sizes, shapes, and compositions of the metal frames in supported mono-, bi-, and multimetallic metal clusters and can even detect the metal atoms in single-metal-atom complexes, as well as providing direct structural information characterizing the metal-support interface. Herein, we assess the major experimental challenges associated with obtaining atomic resolution Z-contrast images of the materials that are highly beam-sensitive, that is, the clusters readily migrate and sinter on support surfaces, and the support itself can drastically change in structure if the experiment is not properly controlled. Calibrated and quantified Z-contrast images are used in conjunction with exsitu analytical measurements and larger-scale characterization methods such as extended X-ray absorption fine structure spectroscopy to generate an atomic-scale understanding of supported catalysts and their function. Examples of the application of these methods include the characterization of a wide range of sizes and compositions of supported clusters, primarily those incorporating Ir, Os, and Au, on highly crystalline supports (zeolites and MgO).

  6. Imaging Single Atoms Using Secondary Electrons with an Aberration-Corrected Electron Microscope

    SciTech Connect

    Zhu, Y.; Inada, H.; Nakamura, K.; Wall, J.

    2009-09-20

    Aberration correction has embarked on a new frontier in electron microscopy by overcoming the limitations of conventional round lenses, providing sub-angstrom-sized probes. However, improvement of spatial resolution using aberration correction so far has been limited to the use of transmitted electrons both in scanning and stationary mode, with an improvement of 20-40%. In contrast, advances in the spatial resolution of scanning electron microscopes (SEMs), which are by far the most widely used instrument for surface imaging at the micrometre-nanometre scale, have been stagnant, despite several recent efforts. Here, we report a new SEM, with aberration correction, able to image single atoms by detecting electrons emerging from its surface as a result of interaction with the small probe. The spatial resolution achieved represents a fourfold improvement over the best-reported resolution in any SEM. Furthermore, we can simultaneously probe the sample through its entire thickness with transmitted electrons. This ability is significant because it permits the selective visualization of bulk atoms and surface ones, beyond a traditional two-dimensional projection in transmission electron microscopy. It has the potential to revolutionize the field of microscopy and imaging, thereby opening the door to a wide range of applications, especially when combined with simultaneous nanoprobe spectroscopy.

  7. Aberration-corrected STEM for atomic-resolution imaging and analysis.

    PubMed

    Krivanek, O L; Lovejoy, T C; Dellby, N

    2015-09-01

    Aberration-corrected scanning transmission electron microscopes are able to form electron beams smaller than 100 pm, which is about half the size of an average atom. Probing materials with such beams leads to atomic-resolution images, electron energy loss and energy-dispersive X-ray spectra obtained from single atomic columns and even single atoms, and atomic-resolution elemental maps. We review briefly how such electron beams came about, and show examples of applications. We also summarize recent developments that are propelling aberration-corrected scanning transmission electron microscopes in new directions, such as complete control of geometric aberration up to fifth order, and ultra-high-energy resolution EELS that is allowing vibrational spectroscopy to be carried out in the electron microscope.

  8. Impact of dynamical scattering on quantitative contrast for aberration-corrected transmission electron microscope images.

    PubMed

    Wen, C; Smith, David J

    2016-10-01

    Aberration-corrected transmission electron microscope images taken under optimum-defocus conditions or processed offline can correctly reflect the projected crystal structure with atomic resolution. However, dynamical scattering, which will seriously influence image contrast, is still unavoidable. Here, the multislice image simulation approach was used to quantify the impact of dynamical scattering on the contrast of aberration-corrected images for a 3C-SiC specimen with changes in atomic occupancy and thickness. Optimum-defocus images with different spherical aberration (CS) coefficients, and structure images restored by deconvolution processing, were studied. The results show that atomic-column positions and the atomic occupancy for SiC 'dumbbells' can be determined by analysis of image contrast profiles only below a certain thickness limit. This limit is larger for optimum-defocus and restored structure images with negative CS coefficient than those with positive CS coefficient. The image contrast of C (or Si) atomic columns with specific atomic occupancy changes differently with increasing crystal thickness. Furthermore, contrast peaks for C atomic columns overlapping with neighboring peaks of Si atomic columns with varied Si atomic occupancy, which is enhanced with increasing crystal thickness, can be neglected in restored structure images, but the effect is substantial in optimum-defocus images.

  9. Bright-field imaging of compound semiconductors using aberration-corrected scanning transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Aoki, Toshihiro; Lu, Jing; McCartney, Martha R.; Smith, David J.

    2016-09-01

    This study reports the observation of six different zincblende compound semiconductors in [110] projection using large-collection-angle bright-field (LABF) imaging with an aberration-corrected scanning transmission electron microscope. Phase contrast is completely suppressed when the collection semi-angle is set equal to the convergence semi-angle and there are no reversals in image contrast with changes in defocus or thickness. The optimum focus for imaging closely separated pairs of atomic columns (‘dumbbells’) is unique and easily recognized, and the positions of atomic columns occupied by heavier atoms always have darker intensity than those occupied by lighter atoms. Thus, the crystal polarity of compound semiconductors can be determined unambiguously. Moreover, it is concluded that the LABF imaging mode will be highly beneficial for studying other more complicated heterostructures at the atomic scale.

  10. Phase-contrast imaging in aberration-corrected scanning transmission electron microscopy.

    PubMed

    Krumeich, F; Müller, E; Wepf, R A

    2013-06-01

    Although the presence of phase-contrast information in bright field images recorded with a scanning transmission electron microscope (STEM) has been known for a long time, its systematic exploitation for the structural characterization of materials began only with the availability of aberration-corrected microscopes that allow sufficiently large illumination angles. Today, phase-contrast STEM (PC-STEM) imaging represents an increasingly important alternative to the well-established HRTEM method. In both methods, the image contrast is coherently generated and thus depends not only on illumination and collection angles but on defocus and specimen thickness as well. By PC-STEM, a projection of the crystal potential is obtained in thin areas, with the scattering sites being represented either with dark or bright contrast at two different defocus values which are both close to Gaussian defocus. This imaging behavior can be further investigated by image simulations performed with standard HRTEM simulation software based on the principle of reciprocity. As examples for the application of this method, PC-STEM results obtained on metal nanoparticles and dodecagonal quasicrystals dd-(Ta,V)₁.₆Te are discussed.

  11. Phase aberration correction by multi-stencils fast marching method using sound speed image in ultrasound computed tomography

    NASA Astrophysics Data System (ADS)

    Qu, Xiaolei; Azuma, Takashi; Lin, Hongxiang; Imoto, Haruka; Tamano, Satoshi; Takagi, Shu; Umemura, Shin-Ichiro; Sakuma, Ichiro; Matsumoto, Yoichiro

    2016-04-01

    Reflection image from ultrasound computed tomography (USCT) system can be obtained by synthetic aperture technique, however its quality is decreased by phase aberration caused by inhomogeneous media. Therefore, phase aberration correction is important to improve image quality. In this study, multi-stencils fast marching method (MSFMM) is employed for phase correction. The MSFMM is an accurate and fast solution of Eikonal equation which considers the refraction. The proposed method includes two steps. First, the MSFMM is used to compute sound propagation time from each element to each image gird point using sound speed image of USCT. Second, synthetic aperture technique is employed to obtain reflection image using the computed propagation time. To evaluate the proposed method, both numerical simulation and phantom experiment were conducted. With regard to numerical simulation, both quantitative and qualitative comparisons between reflection images with and without phase aberration correction were given. In the quantitative comparison, the diameters of point spread function (PSF) in reflection images of a two layer structure were presented. In the qualitative comparison, reflection images of simple circle and complex breast modes with phase aberration correction show higher quality than that without the correction. In respect to phantom experiment, a piece of breast phantom with artificial glandular structure inside was scanned by a USCT prototype, and the artificial glandular structure is able to be visible more clearly in the reflection image with phase aberration correction than in that without the correction. In this study, a phase aberration correction method by the MSFMM are proposed for reflection image of the USCT.

  12. Simultaneous atomic-resolution electron ptychography and Z-contrast imaging of light and heavy elements in complex nanostructures

    NASA Astrophysics Data System (ADS)

    Yang, H.; Rutte, R. N.; Jones, L.; Simson, M.; Sagawa, R.; Ryll, H.; Huth, M.; Pennycook, T. J.; Green, M. L. H.; Soltau, H.; Kondo, Y.; Davis, B. G.; Nellist, P. D.

    2016-08-01

    The aberration-corrected scanning transmission electron microscope (STEM) has emerged as a key tool for atomic resolution characterization of materials, allowing the use of imaging modes such as Z-contrast and spectroscopic mapping. The STEM has not been regarded as optimal for the phase-contrast imaging necessary for efficient imaging of light materials. Here, recent developments in fast electron detectors and data processing capability is shown to enable electron ptychography, to extend the capability of the STEM by allowing quantitative phase images to be formed simultaneously with incoherent signals. We demonstrate this capability as a practical tool for imaging complex structures containing light and heavy elements, and use it to solve the structure of a beam-sensitive carbon nanostructure. The contrast of the phase image contrast is maximized through the post-acquisition correction of lens aberrations. The compensation of defocus aberrations is also used for the measurement of three-dimensional sample information through post-acquisition optical sectioning.

  13. Simultaneous atomic-resolution electron ptychography and Z-contrast imaging of light and heavy elements in complex nanostructures

    PubMed Central

    Yang, H.; Rutte, R. N.; Jones, L.; Simson, M.; Sagawa, R.; Ryll, H.; Huth, M.; Pennycook, T. J.; Green, M.L.H.; Soltau, H.; Kondo, Y.; Davis, B. G.; Nellist, P. D.

    2016-01-01

    The aberration-corrected scanning transmission electron microscope (STEM) has emerged as a key tool for atomic resolution characterization of materials, allowing the use of imaging modes such as Z-contrast and spectroscopic mapping. The STEM has not been regarded as optimal for the phase-contrast imaging necessary for efficient imaging of light materials. Here, recent developments in fast electron detectors and data processing capability is shown to enable electron ptychography, to extend the capability of the STEM by allowing quantitative phase images to be formed simultaneously with incoherent signals. We demonstrate this capability as a practical tool for imaging complex structures containing light and heavy elements, and use it to solve the structure of a beam-sensitive carbon nanostructure. The contrast of the phase image contrast is maximized through the post-acquisition correction of lens aberrations. The compensation of defocus aberrations is also used for the measurement of three-dimensional sample information through post-acquisition optical sectioning. PMID:27561914

  14. Simultaneous atomic-resolution electron ptychography and Z-contrast imaging of light and heavy elements in complex nanostructures.

    PubMed

    Yang, H; Rutte, R N; Jones, L; Simson, M; Sagawa, R; Ryll, H; Huth, M; Pennycook, T J; Green, M L H; Soltau, H; Kondo, Y; Davis, B G; Nellist, P D

    2016-01-01

    The aberration-corrected scanning transmission electron microscope (STEM) has emerged as a key tool for atomic resolution characterization of materials, allowing the use of imaging modes such as Z-contrast and spectroscopic mapping. The STEM has not been regarded as optimal for the phase-contrast imaging necessary for efficient imaging of light materials. Here, recent developments in fast electron detectors and data processing capability is shown to enable electron ptychography, to extend the capability of the STEM by allowing quantitative phase images to be formed simultaneously with incoherent signals. We demonstrate this capability as a practical tool for imaging complex structures containing light and heavy elements, and use it to solve the structure of a beam-sensitive carbon nanostructure. The contrast of the phase image contrast is maximized through the post-acquisition correction of lens aberrations. The compensation of defocus aberrations is also used for the measurement of three-dimensional sample information through post-acquisition optical sectioning. PMID:27561914

  15. Theoretical aspects of image formation in the aberration-corrected electron microscope.

    PubMed

    Rose, H

    2010-04-01

    The theoretical aspects of image formation in the transmission electron microscope (TEM) are outlined and revisited in detail by taking into account the elastic and inelastic scattering. In particular, the connection between the exit wave and the scattering amplitude is formulated for non-isoplanatic conditions. Different imaging modes are investigated by utilizing the scattering amplitude and employing the generalized optical theorem. A novel obstruction-free anamorphotic phase shifter is proposed which enables one to shift the phase of the scattered wave by an arbitrary amount over a large range of spatial frequencies. In the optimum case, the phase of the scattered wave and the introduced phase shift add up to -pi/2 giving negative contrast. We obtain these optimum imaging conditions by employing an aberration-corrected electron microscope operating at voltages below the knock-on threshold for atom displacement and by shifting optimally the phase of the scattered electron wave. The optimum phase shift is achieved by adjusting appropriately the constant phase shift of the phase plate and the phase shift resulting from the defocus and the spherical aberration of the corrected objective lens. The realization of this imaging mode is the aim of the SALVE project (Sub-A Low-Voltage Electron microscope).

  16. Aberration correction during real time in vivo imaging of bone marrow with sensorless adaptive optics confocal microscope

    NASA Astrophysics Data System (ADS)

    Wang, Zhibin; Wei, Dan; Wei, Ling; He, Yi; Shi, Guohua; Wei, Xunbin; Zhang, Yudong

    2014-08-01

    We have demonstrated adaptive correction of specimen-induced aberration during in vivo imaging of mouse bone marrow vasculature with confocal fluorescence microscopy. Adaptive optics system was completed with wavefront sensorless correction scheme based on stochastic parallel gradient descent algorithm. Using image sharpness as the optimization metric, aberration correction was performed based upon Zernike polynomial modes. The experimental results revealed the improved signal and resolution leading to a substantially enhanced image contrast with aberration correction. The image quality of vessels at 38- and 75-μm depth increased three times and two times, respectively. The corrections allowed us to detect clearer bone marrow vasculature structures at greater contrast and improve the signal-to-noise ratio.

  17. Direct imaging of lithium atoms in LiV₂O₄ by spherical aberration-corrected electron microscopy.

    PubMed

    Oshima, Yoshifumi; Sawada, Hidetaka; Hosokawa, Fumio; Okunishi, Eiji; Kaneyama, Toshikatsu; Kondo, Yukihito; Niitaka, Seiji; Takagi, Hidenori; Tanishiro, Yasumasa; Takayanagi, Kunio

    2010-01-01

    We visualized lithium atom columns in LiV₂O₄ crystals by combining scanning transmission electron microscopy with annular bright field (ABF) imaging using a spherical aberration-corrected electron microscope (R005) viewed from the [110] direction. The incident electron beam was coherent with a convergent angle of 30 mrad (semi-angle), and the detector collected scattered electrons over 20-30 mrad (semi-angle). The ABF image showed dark dots corresponding to lithium, vanadium and oxygen columns. PMID:20406731

  18. Direct imaging of light elements by annular dark-field aberration-corrected scanning transmission electron microscopy

    SciTech Connect

    Lotnyk, Andriy Poppitz, David; Gerlach, Jürgen W.; Rauschenbach, Bernd

    2014-02-17

    In this report, we show that an annular dark-field detector in an aberration-corrected scanning transmission electron microscope allows the direct observation of light element columns in crystalline lattices. At specific imaging conditions, an enhancement of the intensities of light element columns in the presence of heavy element columns is observed. Experimental results are presented for imaging the nitrogen and carbon atomic columns at the GaN-SiC interface and within the GaN and SiC compounds. The crystal polarity of GaN at the interface is identified. The obtained findings are discussed and are well supported by image simulations.

  19. Direct imaging of light elements by annular dark-field aberration-corrected scanning transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Lotnyk, Andriy; Poppitz, David; Gerlach, Jürgen W.; Rauschenbach, Bernd

    2014-02-01

    In this report, we show that an annular dark-field detector in an aberration-corrected scanning transmission electron microscope allows the direct observation of light element columns in crystalline lattices. At specific imaging conditions, an enhancement of the intensities of light element columns in the presence of heavy element columns is observed. Experimental results are presented for imaging the nitrogen and carbon atomic columns at the GaN-SiC interface and within the GaN and SiC compounds. The crystal polarity of GaN at the interface is identified. The obtained findings are discussed and are well supported by image simulations.

  20. Migration of Single Iridium Atoms and Tri-iridium Clusters on MgO Surfaces. Aberration-Corrected STEM Imaging and ab-initio Calculations

    SciTech Connect

    Han, Chang W.; Iddir, Hakim; Uzun, Alper; Curtiss, Larry A.; Browning, Nigel D.; Gates, Bruce C.; Ortalan, Volkan

    2015-11-06

    To address the challenge of fast, direct atomic-scale visualization of the diffusion of atoms and clusters on surfaces, we used aberration-corrected scanning transmission electron microscopy (STEM) with high scan speeds (as little as ~0.1 s per frame) to visualize the diffusion of (1) a heavy atom (Ir) on the surface of a support consisting of light atoms, MgO(100), and (2) an Ir3 cluster on MgO(110). Sequential Z-contrast images elucidate the diffusion mechanisms, including the hopping of Ir1 and the rotational migration of Ir3 as two Ir atoms remain anchored to the surface. Density functional theory (DFT) calculations provided estimates of the diffusion energy barriers and binding energies of the iridium species to the surfaces. The results show how the combination of fast-scan STEM and DFT calculations allow real-time visualization and fundamental understanding of surface diffusion phenomena pertaining to supported catalysts and other materials.

  1. Aberration-corrected STEM imaging of Ag on gamma-Al2O3.

    PubMed

    Blom, Douglas A; Allard, Lawrence F; Narula, Chaitanya K; Moses-DeBusk, Melanie J

    2008-02-01

    Ag on gamma-alumina is a promising catalyst for hydrocarbon selective catalytic reduction in lean-burn gasoline and diesel engines for transportation applications. Although much is known about the mechanism of NOx reduction and the various intermediates, little agreement exists on the nature of the active silver species. In the present work, aberration-corrected STEM has provided new information about the nature of Ag on alumina both as impregnated and following treatments at various temperatures with exposure to simulated exhaust gas. Ex situ techniques have provided new insights into the evolution of Ag on alumina following exposure to temperature and simulated exhaust gas.

  2. Synergistic enhancements of ultrasound image contrast with a combination of phase aberration correction and dual apodization with cross-correlation.

    PubMed

    Shin, Junseob; Yen, Jesse T

    2012-09-01

    Dual apodization with cross-correlation (DAX) is a novel adaptive beamforming technique which utilizes two distinct apodization functions in suppressing side lobes and clutter. Previous studies have shown that the performance of DAX in minimizing the effects of phase aberration diminishes with increasing aberrator strength. To achieve greater improvement in image contrast, we propose, in this paper, to combine DAX with a phase aberration correction algorithm based on nearest-neighbor cross-correlation (NNCC). Our simulation and experimental results presented in this work showed that the proposed method allows for synergistic enhancements of image contrast and achieves greater improvement in image quality than using DAX alone or phase aberration correction alone in the presence of weak and strong aberrators. Compared with standard delay-and-sum (DAS) beamforming, using the proposed method on simulated data with weak and strong aberrations increased the contrast-to-noise ratio (CNR) values from 4.10 to 10.96 and from 1.69 to 9.80, respectively. Experimental results were obtained using pork tissues of 4 and 10 mm thickness and a tissue-mimicking phantom. The CNR values increased from 3.74 to 9.72 for the 4-mm pork aberrator and from 1.27 to 8.17 for the 10-mm pork aberrator. PMID:23007784

  3. Aberration corrected emittance exchange

    NASA Astrophysics Data System (ADS)

    Nanni, E. A.; Graves, W. S.

    2015-08-01

    Full exploitation of emittance exchange (EEX) requires aberration-free performance of a complex imaging system including active radio-frequency (rf) elements which can add temporal distortions. We investigate the performance of an EEX line where the exchange occurs between two dimensions with normalized emittances which differ by multiple orders of magnitude. The transverse emittance is exchanged into the longitudinal dimension using a double dogleg emittance exchange setup with a five cell rf deflector cavity. Aberration correction is performed on the four most dominant aberrations. These include temporal aberrations that are corrected with higher order magnetic optical elements located where longitudinal and transverse emittance are coupled. We demonstrate aberration-free performance of an EEX line with emittances differing by four orders of magnitude, i.e., an initial transverse emittance of 1 pm-rad is exchanged with a longitudinal emittance of 10 nm-rad.

  4. Incoherent imaging by Z-contrast stem: Towards 1 Angstrom resolution

    NASA Astrophysics Data System (ADS)

    Pennycook, S. J.; Jesson, D. E.; McGibbon, A. J.

    1993-12-01

    By averaging phase correlations between scattered electrons, a high angle detector in the scanning transmission electron microscope (STEM) can provide an incoherent, Z-contrast image at atomic resolution. Phase coherence is effectively destroyed through a combination of detector geometry (transverse incoherence) and phonon scattering (longitudinal incoherence). Besides having a higher intrinsic resolution, incoherent imaging offers the possibility of robust reconstruction to higher resolutions, provided that some lower frequency information is present in the image. This should have value for complex materials and regions of complex atomic arrangements such as grain boundaries. Direct resolution of the GaAs sublattice with a 300 kV STEM is demonstrated.

  5. Comparison of analytical and numerical approaches for CT-based aberration correction in transcranial passive acoustic imaging

    NASA Astrophysics Data System (ADS)

    Jones, Ryan M.; Hynynen, Kullervo

    2016-01-01

    Computed tomography (CT)-based aberration corrections are employed in transcranial ultrasound both for therapy and imaging. In this study, analytical and numerical approaches for calculating aberration corrections based on CT data were compared, with a particular focus on their application to transcranial passive imaging. Two models were investigated: a three-dimensional full-wave numerical model (Connor and Hynynen 2004 IEEE Trans. Biomed. Eng. 51 1693-706) based on the Westervelt equation, and an analytical method (Clement and Hynynen 2002 Ultrasound Med. Biol. 28 617-24) similar to that currently employed by commercial brain therapy systems. Trans-skull time delay corrections calculated from each model were applied to data acquired by a sparse hemispherical (30 cm diameter) receiver array (128 piezoceramic discs: 2.5 mm diameter, 612 kHz center frequency) passively listening through ex vivo human skullcaps (n  =  4) to emissions from a narrow-band, fixed source emitter (1 mm diameter, 516 kHz center frequency). Measurements were taken at various locations within the cranial cavity by moving the source around the field using a three-axis positioning system. Images generated through passive beamforming using CT-based skull corrections were compared with those obtained through an invasive source-based approach, as well as images formed without skull corrections, using the main lobe volume, positional shift, peak sidelobe ratio, and image signal-to-noise ratio as metrics for image quality. For each CT-based model, corrections achieved by allowing for heterogeneous skull acoustical parameters in simulation outperformed the corresponding case where homogeneous parameters were assumed. Of the CT-based methods investigated, the full-wave model provided the best imaging results at the cost of computational complexity. These results highlight the importance of accurately modeling trans-skull propagation when calculating CT-based aberration corrections

  6. Digital aberration correction of fluorescent images with coherent holographic image reconstruction by phase transfer (CHIRPT)

    NASA Astrophysics Data System (ADS)

    Field, Jeffrey J.; Bartels, Randy A.

    2016-03-01

    Coherent holographic image reconstruction by phase transfer (CHIRPT) is an imaging method that permits digital holographic propagation of fluorescent light. The image formation process in CHIRPT is based on illuminating the specimen with a precisely controlled spatio-temporally varying intensity pattern. This pattern is formed by focusing a spatially coherent illumination beam to a line focus on a spinning modulation mask, and image relaying the mask plane to the focal plane of an objective lens. Deviations from the designed spatio-temporal illumination pattern due to imperfect mounting of the circular modulation mask onto the rotation motor induce aberrations in the recovered image. Here we show that these aberrations can be measured and removed non-iteratively by measuring the disk aberration phase externally. We also demonstrate measurement and correction of systematic optical aberrations in the CHIRPT microscope.

  7. Aberration correction for transcranial photoacoustic tomography of primates employing adjunct image data

    NASA Astrophysics Data System (ADS)

    Huang, Chao; Nie, Liming; Schoonover, Robert W.; Guo, Zijian; Schirra, Carsten O.; Anastasio, Mark A.; Wang, Lihong V.

    2012-06-01

    A challenge in photoacoustic tomography (PAT) brain imaging is to compensate for aberrations in the measured photoacoustic data due to their propagation through the skull. By use of information regarding the skull morphology and composition obtained from adjunct x-ray computed tomography image data, we developed a subject-specific imaging model that accounts for such aberrations. A time-reversal-based reconstruction algorithm was employed with this model for image reconstruction. The image reconstruction methodology was evaluated in experimental studies involving phantoms and monkey heads. The results establish that our reconstruction methodology can effectively compensate for skull-induced acoustic aberrations and improve image fidelity in transcranial PAT.

  8. Separating strain from composition in unit cell parameter maps obtained from aberration corrected high resolution transmission electron microscopy imaging

    SciTech Connect

    Schulz, T.; Remmele, T.; Korytov, M.; Markurt, T.; Albrecht, M.; Duff, A.; Lymperakis, L.; Neugebauer, J.; Chèze, C.

    2014-01-21

    Based on the evaluation of lattice parameter maps in aberration corrected high resolution transmission electron microscopy images, we propose a simple method that allows quantifying the composition and disorder of a semiconductor alloy at the unit cell scale with high accuracy. This is realized by considering, next to the out-of-plane, also the in-plane lattice parameter component allowing to separate the chemical composition from the strain field. Considering only the out-of-plane lattice parameter component not only yields large deviations from the true local alloy content but also carries the risk of identifying false ordering phenomena like formations of chains or platelets. Our method is demonstrated on image simulations of relaxed supercells, as well as on experimental images of an In{sub 0.20}Ga{sub 0.80}N quantum well. Principally, our approach is applicable to all epitaxially strained compounds in the form of quantum wells, free standing islands, quantum dots, or wires.

  9. High performance Czerny-Turner imaging spectrometer with aberrations corrected by tilted lenses

    NASA Astrophysics Data System (ADS)

    Zhong, Xing; Zhang, Yuan; Jin, Guang

    2015-03-01

    The design of the high performance imaging spectrometer using low-cost plane grating is researched in this paper. In order to correct the aberrations well, under the guidance of the vector aberration theory, the modification of Czerny-Turner system with inserted tilt lenses is proposed. The novel design of a short-wave infrared imaging spectrometer working at between wavelengths of 1-2.5 μm is shown as an example, whose numerical aperture achieves 0.15 in image space. The aberrations are corrected well and the Modulation Transfer Function (MTF) performance is the same as the convex gratings systems. The smiles and keystones of the spectral image are acceptable. Advantages of the proposed design with a plane grating are obviously that the diffraction efficiency is high while the cost is very low.

  10. Chromatic Aberration Correction for Atomic Resolution TEM Imaging from 20 to 80 kV.

    PubMed

    Linck, Martin; Hartel, Peter; Uhlemann, Stephan; Kahl, Frank; Müller, Heiko; Zach, Joachim; Haider, Max; Niestadt, Marcel; Bischoff, Maarten; Biskupek, Johannes; Lee, Zhongbo; Lehnert, Tibor; Börrnert, Felix; Rose, Harald; Kaiser, Ute

    2016-08-12

    Atomic resolution in transmission electron microscopy of thin and light-atom materials requires a rigorous reduction of the beam energy to reduce knockon damage. However, at the same time, the chromatic aberration deteriorates the resolution of the TEM image dramatically. Within the framework of the SALVE project, we introduce a newly developed C_{c}/C_{s} corrector that is capable of correcting both the chromatic and the spherical aberration in the range of accelerating voltages from 20 to 80 kV. The corrector allows correcting axial aberrations up to fifth order as well as the dominating off-axial aberrations. Over the entire voltage range, optimum phase-contrast imaging conditions for weak signals from light atoms can be adjusted for an optical aperture of at least 55 mrad. The information transfer within this aperture is no longer limited by chromatic aberrations. We demonstrate the performance of the microscope using the examples of 30 kV phase-contrast TEM images of graphene and molybdenum disulfide, showing unprecedented contrast and resolution that matches image calculations. PMID:27563976

  11. Chromatic Aberration Correction for Atomic Resolution TEM Imaging from 20 to 80 kV

    NASA Astrophysics Data System (ADS)

    Linck, Martin; Hartel, Peter; Uhlemann, Stephan; Kahl, Frank; Müller, Heiko; Zach, Joachim; Haider, Max.; Niestadt, Marcel; Bischoff, Maarten; Biskupek, Johannes; Lee, Zhongbo; Lehnert, Tibor; Börrnert, Felix; Rose, Harald; Kaiser, Ute

    2016-08-01

    Atomic resolution in transmission electron microscopy of thin and light-atom materials requires a rigorous reduction of the beam energy to reduce knockon damage. However, at the same time, the chromatic aberration deteriorates the resolution of the TEM image dramatically. Within the framework of the SALVE project, we introduce a newly developed Cc/Cs corrector that is capable of correcting both the chromatic and the spherical aberration in the range of accelerating voltages from 20 to 80 kV. The corrector allows correcting axial aberrations up to fifth order as well as the dominating off-axial aberrations. Over the entire voltage range, optimum phase-contrast imaging conditions for weak signals from light atoms can be adjusted for an optical aperture of at least 55 mrad. The information transfer within this aperture is no longer limited by chromatic aberrations. We demonstrate the performance of the microscope using the examples of 30 kV phase-contrast TEM images of graphene and molybdenum disulfide, showing unprecedented contrast and resolution that matches image calculations.

  12. Pitch-catch phase aberration correction of multiple isoplanatic patches for 3-D transcranial ultrasound imaging.

    PubMed

    Lindsey, Brooks D; Smith, Stephen W

    2013-03-01

    Having previously presented the ultrasound brain helmet, a system for simultaneous 3-D ultrasound imaging via both temporal bone acoustic windows, the scanning geometry of this system is utilized to allow each matrix array to serve as a correction source for the opposing array. Aberration is estimated using cross-correlation of RF channel signals, followed by least mean squares solution of the resulting overdetermined system. Delay maps are updated and real-time 3-D scanning resumes. A first attempt is made at using multiple arrival time maps to correct multiple unique aberrators within a single transcranial imaging volume, i.e., several isoplanatic patches. This adaptive imaging technique, which uses steered unfocused waves transmitted by the opposing, or beacon, array, updates the transmit and receive delays of 5 isoplanatic patches within a 64° x 64° volume. In phantom experiments, color flow voxels above a common threshold have also increased by an average of 92%, whereas color flow variance decreased by an average of 10%. This approach has been applied to both temporal acoustic windows of two human subjects, yielding increases in echo brightness in 5 isoplanatic patches with a mean value of 24.3 ± 9.1%, suggesting that such a technique may be beneficial in the future for performing noninvasive 3-D color flow imaging of cerebrovascular disease, including stroke.

  13. Pitch–Catch Phase Aberration Correction of Multiple Isoplanatic Patches for 3-D Transcranial Ultrasound Imaging

    PubMed Central

    Lindsey, Brooks D.; Smith, Stephen W.

    2013-01-01

    Having previously presented the ultrasound brain helmet, a system for simultaneous 3-D ultrasound imaging via both temporal bone acoustic windows, the scanning geometry of this system is utilized to allow each matrix array to serve as a correction source for the opposing array. Aberration is estimated using cross-correlation of RF channel signals, followed by least mean squares solution of the resulting overdetermined system. Delay maps are updated and real-time 3-D scanning resumes. A first attempt is made at using multiple arrival time maps to correct multiple unique aberrators within a single transcranial imaging volume, i.e., several isoplanatic patches. This adaptive imaging technique, which uses steered unfocused waves transmitted by the opposing, or beacon, array, updates the transmit and receive delays of 5 isoplanatic patches within a 64° × 64° volume. In phantom experiments, color flow voxels above a common threshold have also increased by an average of 92%, whereas color flow variance decreased by an average of 10%. This approach has been applied to both temporal acoustic windows of two human subjects, yielding increases in echo brightness in 5 isoplanatic patches with a mean value of 24.3 ± 9.1%, suggesting that such a technique may be beneficial in the future for performing noninvasive 3-D color flow imaging of cerebrovascular disease, including stroke. PMID:23475914

  14. Chromatic aberration correction and deconvolution for UV sensitive imaging of fluorescent sterols in cytoplasmic lipid droplets.

    PubMed

    Wüstner, Daniel; Faergeman, Nils J

    2008-08-01

    Intrinsically fluorescent sterols, like dehydroergosterol (DHE), mimic cholesterol closely and are therefore suitable to determine cholesterol transport by fluorescence microscopy. Disadvantages of DHE are its low quantum yield, rapid bleaching, and the fact that its excitation and emission is in the UV region of the spectrum. Thus, one has to deal with chromatic aberration and low signal-to-noise ratio. We developed a method to correct for chromatic aberration between the UV channel and the red/green channel in multicolor imaging of DHE compared with the lipid droplet marker Nile Red in living macrophage foam cells and in adipocytes. We used deconvolution microscopy and developed image segmentation techniques to assess the DHE content of lipid droplets in both cell types in an automated manner. Pulse-chase studies and colocalization analysis were performed to monitor the redistribution of DHE upon adipocyte differentiation. DHE is targeted to transferrin-positive recycling endosomes in preadipocytes but associates with droplets in mature adipocytes. Only in adipocytes but not in foam cells fluorescent sterol was confined to the droplet-limiting membrane. We developed an approach to visualize and quantify sterol content of lipid droplets in living cells with potential for automated high content screening of cellular sterol transport.

  15. Experimental demonstration of passive acoustic imaging in the human skull cavity using CT-based aberration corrections

    PubMed Central

    Jones, Ryan M.; O’Reilly, Meaghan A.; Hynynen, Kullervo

    2015-01-01

    Purpose: Experimentally verify a previously described technique for performing passive acoustic imaging through an intact human skull using noninvasive, computed tomography (CT)-based aberration corrections Jones et al. [Phys. Med. Biol. 58, 4981–5005 (2013)]. Methods: A sparse hemispherical receiver array (30 cm diameter) consisting of 128 piezoceramic discs (2.5 mm diameter, 612 kHz center frequency) was used to passively listen through ex vivo human skullcaps (n = 4) to acoustic emissions from a narrow-band fixed source (1 mm diameter, 516 kHz center frequency) and from ultrasound-stimulated (5 cycle bursts, 1 Hz pulse repetition frequency, estimated in situ peak negative pressure 0.11–0.33 MPa, 306 kHz driving frequency) Definity™ microbubbles flowing through a thin-walled tube phantom. Initial in vivo feasibility testing of the method was performed. The performance of the method was assessed through comparisons to images generated without skull corrections, with invasive source-based corrections, and with water-path control images. Results: For source locations at least 25 mm from the inner skull surface, the modified reconstruction algorithm successfully restored a single focus within the skull cavity at a location within 1.25 mm from the true position of the narrow-band source. The results obtained from imaging single bubbles are in good agreement with numerical simulations of point source emitters and the authors’ previous experimental measurements using source-based skull corrections O’Reilly et al. [IEEE Trans. Biomed. Eng. 61, 1285–1294 (2014)]. In a rat model, microbubble activity was mapped through an intact human skull at pressure levels below and above the threshold for focused ultrasound-induced blood–brain barrier opening. During bursts that led to coherent bubble activity, the location of maximum intensity in images generated with CT-based skull corrections was found to deviate by less than 1 mm, on average, from the position

  16. STEM imaging of 47-pm-separated atomic columns by a spherical aberration-corrected electron microscope with a 300-kV cold field emission gun.

    PubMed

    Sawada, Hidetaka; Tanishiro, Yasumasa; Ohashi, Nobuhiro; Tomita, Takeshi; Hosokawa, Fumio; Kaneyama, Toshikatsu; Kondo, Yukihito; Takayanagi, Kunio

    2009-12-01

    A spherical aberration-corrected electron microscope has been developed recently, which is equipped with a 300-kV cold field emission gun and an objective lens of a small chromatic aberration coefficient. A dumbbell image of 47 pm spacing, corresponding to a pair of atomic columns of germanium aligned along the [114] direction, is resolved in high-angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) with a 0.4-eV energy spread of the electron beam. The observed image was compared with a simulated image obtained by dynamical calculation.

  17. Aberration corrected Lorentz scanning transmission electron microscopy.

    PubMed

    McVitie, S; McGrouther, D; McFadzean, S; MacLaren, D A; O'Shea, K J; Benitez, M J

    2015-05-01

    We present results from an aberration corrected scanning transmission electron microscope which has been customised for high resolution quantitative Lorentz microscopy with the sample located in a magnetic field free or low field environment. We discuss the innovations in microscope instrumentation and additional hardware that underpin the imaging improvements in resolution and detection with a focus on developments in differential phase contrast microscopy. Examples from materials possessing nanometre scale variations in magnetisation illustrate the potential for aberration corrected Lorentz imaging as a tool to further our understanding of magnetism on this lengthscale.

  18. Behavior of Au species in Au/Fe2O3 catalysts characterized by novel in situ heating techniques and aberration-corrected STEM imaging.

    PubMed

    Allard, Lawrence F; Flytzani-Stephanopoulos, Maria; Overbury, Steven H

    2010-08-01

    The recent advent of a novel design of in situ heating technology for electron microscopes has permitted unprecedented control of elevated temperature studies of catalytic materials, particularly when coupled with the sub-Angström imaging performance of a modern aberration-corrected scanning transmission electron microscope (STEM). Using micro-electro-mechanical-systems (MEMS)-based Aduro heating chips from Protochips, Inc. (Raleigh, NC, USA) allows nearly instantaneous heating and cooling of catalyst powders, avoiding effects of temperature ramping as experienced with standard heating stages. The heating technology also provides stable operation limited only by the inherent drift in the microscope stage, thus allowing full image resolution to be achieved even at elevated temperatures. The present study details the use of both the high X-Y spatial resolution in both dark-field and simultaneous bright-field imaging, along with the high resolution in Z (depth sectioning) provided by the large probe incidence semiangle in the aberration-corrected instrument, to characterize the evolution of microstructure in a commercial Au/Fe2O3 water-gas shift catalyst during elevated temperature treatment. The phenomenon of Au diffusion to the surface of hematite support particles to form discrete crystalline Au nanoparticles in the 1-2 nm size range, after a prior leaching treatment to remove surface Au species has been characterized.

  19. Atomic scale structure and chemistry of interfaces by Z-contrast imaging and electron energy loss spectroscopy in the STEM

    SciTech Connect

    McGibbon, M.M.; Browning, N.D.; Chisholm, M.F.; Pennycook, S.J.

    1993-12-01

    The macroscopic properties of many materials are controlled by the structure and chemistry at the grain boundaries. A basic understanding of the structure-property relationship requires a technique which probes both composition and chemical bonding on an atomic scale. The high-resolution Z-contrast imaging technique in the scanning transmission electron microscope (STEM) forms an incoherent image in which changes in atomic structure and composition can be interpreted intuitively. This direct image allows the electron probe to be positioned over individual atomic columns for parallel detection electron energy loss spectroscopy (PEELS) at a spatial resolution approaching 0.22nm. The bonding information which can be obtained from the fine structure within the PEELS edges can then be used in conjunction with the Z-contrast images to determine the structure at the grain boundary. In this paper we present 3 examples of correlations between the structural, chemical and electronic properties at materials interfaces in metal-semiconductor systems, superconducting and ferroelectric materials.

  20. Restoring defect structures in 3C-SiC/Si (001) from spherical aberration-corrected high-resolution transmission electron microscope images by means of deconvolution processing.

    PubMed

    Wen, C; Wan, W; Li, F H; Tang, D

    2015-04-01

    The [110] cross-sectional samples of 3C-SiC/Si (001) were observed with a spherical aberration-corrected 300 kV high-resolution transmission electron microscope. Two images taken not close to the Scherzer focus condition and not representing the projected structures intuitively were utilized for performing the deconvolution. The principle and procedure of image deconvolution and atomic sort recognition are summarized. The defect structure restoration together with the recognition of Si and C atoms from the experimental images has been illustrated. The structure maps of an intrinsic stacking fault in the area of SiC, and of Lomer and 60° shuffle dislocations at the interface have been obtained at atomic level.

  1. Local symmetry breaking of a thin crystal structure of β-Si3N4 as revealed by spherical aberration corrected high-resolution transmission electron microscopy images.

    PubMed

    Kim, Hwang Su; Zhang, Zaoli; Kaiser, Ute

    2012-06-01

    This report is an extension of the study for structural imaging of 5-6 nm thick β-Si(3)N(4) [0001] crystal with a spherical aberration corrected transmission electron microscope by Zhang and Kaiser [2009. Structure imaging of β-Si(3)N(4) by spherical aberration-corrected high-resolution transmission electron microscopy. Ultramicroscopy 109, 1114-1120]. In this work, a local symmetry breaking with an uneven resolution of dumbbells in the six-membered rings revealed in the reported images in the study of Zhang and Kaiser has been analyzed in detail. It is found that this local asymmetry in the image basically is not relevant to a slight mistilt of the specimen and/or a beam tilt (coma). Rather the certain variation of the tetrahedral bond length of Si-N(4) in the crystal structure is found to be responsible for the uneven resolution with a local structural variation from region to region. This characteristic of the variation is also supposed to give a distorted lattice of apparently 2°-2.5° deviations from the perfect hexagonal unit cell as observed in the reported image in the work of Zhang and Kaiser. It is discussed that this variation may prevail only in a thin specimen with a thickness ranging ~≤ 5-6 nm. At the same time, it is noted that the average of the bond length variation is close to the fixed length known in a bulk crystal of β-Si(3)N(4).

  2. Direct atomic-scale imaging of hydrogen and oxygen interstitials in pure niobium using atom-probe tomography and aberration-corrected scanning transmission electron microscopy.

    PubMed

    Kim, Yoon-Jun; Tao, Runzhe; Klie, Robert F; Seidman, David N

    2013-01-22

    Imaging the three-dimensional atomic-scale structure of complex interfaces has been the goal of many recent studies, due to its importance to technologically relevant areas. Combining atom-probe tomography and aberration-corrected scanning transmission electron microscopy (STEM), we present an atomic-scale study of ultrathin (~5 nm) native oxide layers on niobium (Nb) and the formation of ordered niobium hydride phases near the oxide/Nb interface. Nb, an elemental type-II superconductor with the highest critical temperature (T(c) = 9.2 K), is the preferred material for superconducting radio frequency (SRF) cavities in next-generation particle accelerators. Nb exhibits high solubilities for oxygen and hydrogen, especially within the RF-field penetration depth, which is believed to result in SRF quality factor losses. STEM imaging and electron energy-loss spectroscopy followed by ultraviolet laser-assisted local-electrode atom-probe tomography on the same needle-like sample reveals the NbO(2), Nb(2)O(5), NbO, Nb stacking sequence; annular bright-field imaging is used to visualize directly hydrogen atoms in bulk β-NbH.

  3. Aberration-corrected X-ray spectrum imaging and Fresnel contrast to differentiate nanoclusters and cavities in helium-irradiated alloy 14YWT

    SciTech Connect

    Miller, Michael K; Parish, Chad M

    2014-01-01

    Helium accumulation negatively impacts structural materials used in neutron-irradiated environments, such as fission and fusion reactors. Next-generation fission and fusion reactors will require structural materials, such as steels, resistant to large neutron doses yet see service temperatures in the range most affected by helium embrittlement. Previous work has indicated the difficulty of experimentally differentiating nanometer-sized helium bubbles from the Ti-Y-O rich nanoclustsers (NCs) in radiation-tolerant nanostructured ferritic alloys (NFAs). Because the NCs are expected to sequester helium away from grain boundaries and reduce embrittlement, experimental methods to study simultaneously the NC and bubble populations are needed. In this study, aberration-corrected scanning transmission electron microscopy (STEM) results combining high-collection-efficiency X-ray spectrum images (SIs), multivariate statistical analysis (MVSA), and Fresnel-contrast bright-field STEM imaging have been used for such a purpose. Results indicate that Fresnel-contrast imaging, with careful attention to TEM-STEM reciprocity, differentiates bubbles from NCs, and MVSA of X-ray SIs unambiguously identifies NCs. Therefore, combined Fresnel-contrast STEM and X-ray SI is an effective STEM-based method to characterize helium-bearing NFAs.

  4. Simultaneous fluorescence and high-resolution bright-field imaging with aberration correction over a wide field-of-view with Fourier ptychographic microscopy (FPM) (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Chung, Jaebum; Kim, Jinho; Ou, Xiaoze; Horstmeyer, Roarke; Yang, Changhuei

    2016-03-01

    We present a method to acquire both fluorescence and high-resolution bright-field images with correction for the spatially varying aberrations over a microscope's wide field-of-view (FOV). First, the procedure applies Fourier ptychographic microscopy (FPM) to retrieve the amplitude and phase of a sample, at a resolution that significantly exceeds the cutoff frequency of the microscope objective lens. At the same time, FPM algorithm is able to leverage on the redundancy within the set of acquired FPM bright-field images to estimate the microscope aberrations, which usually deteriorate in regions further away from the FOV's center. Second, the procedure acquires a raw wide-FOV fluorescence image within the same setup. Lack of moving parts allows us to use the FPM-estimated aberration map to computationally correct for the aberrations in the fluorescence image through deconvolution. Overlaying the aberration-corrected fluorescence image on top of the high-resolution bright-field image can be done with accurate spatial correspondence. This can provide means to identifying fluorescent regions of interest within the context of the sample's bright-field information. An experimental demonstration successfully improves the bright-field resolution of fixed, stained and fluorescently tagged HeLa cells by a factor of 4.9, and reduces the error caused by aberrations in a fluorescence image by 31%, over a field of view of 6.2 mm by 9.3 mm. For optimal deconvolution, we show the fluorescence image needs to have a signal-to-noise ratio of ~18.

  5. Magnitude of speed of sound aberration corrections for ultrasound image guided radiotherapy for prostate and other anatomical sites

    SciTech Connect

    Fontanarosa, Davide; Meer, Skadi van der; Bloemen-van Gurp, Esther; Stroian, Gabriela; Verhaegen, Frank

    2012-08-15

    Purpose: The purpose of this work is to assess the magnitude of speed of sound (SOS) aberrations in three-dimensional ultrasound (US) imaging systems in image guided radiotherapy. The discrepancy between the fixed SOS value of 1540 m/s assumed by US systems in human soft tissues and its actual nonhomogeneous distribution in patients produces small but systematic errors of up to a few millimeters in the positions of scanned structures. Methods: A correction, provided by a previously published density-based algorithm, was applied to a set of five prostate, five liver, and five breast cancer patients. The shifts of the centroids of target structures and the change in shape were evaluated. Results: After the correction the prostate cases showed shifts up to 3.6 mm toward the US probe, which may explain largely the reported positioning discrepancies in the literature on US systems versus other imaging modalities. Liver cases showed the largest changes in volume of the organ, up to almost 9%, and shifts of the centroids up to more than 6 mm either away or toward the US probe. Breast images showed systematic small shifts of the centroids toward the US probe with a maximum magnitude of 1.3 mm. Conclusions: The applied correction in prostate and liver cancer patients shows positioning errors of several mm due to SOS aberration; the errors are smaller in breast cancer cases, but possibly becoming more important when breast tissue thickness increases.

  6. A speed of sound aberration correction algorithm for curvilinear ultrasound transducers in ultrasound-based image-guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Fontanarosa, Davide; Pesente, Silvia; Pascoli, Francesco; Ermacora, Denis; Abu Rumeileh, Imad; Verhaegen, Frank

    2013-03-01

    Conventional ultrasound (US) devices use the time of flight (TOF) of reflected US pulses to calculate distances inside the scanned tissues and thus create images. The speed of sound (SOS) is assumed to be constant in all human soft tissues at a generally accepted average value of 1540 m s-1. This assumption is a source of systematic errors up to several millimeters and of image distortion in quantitative US imaging. In this work, an extension of a method recently published by Fontanarosa et al (2011 Med. Phys. 38 2665-73) is presented: the aim is to correct SOS aberrations in three-dimensional (3D) US images in those cases where a spatially co-registered computerized tomography (CT) scan is also available; the algorithm is then applicable to a more general case where the lines of view (LOV) of the US device are not necessarily parallel and coplanar, thus allowing correction also for US transducers other than linear. The algorithm was applied on a multi-modality pelvic US phantom, scanned through three different liquid layers on top of the phantom with different SOS values; the results show that the correction restores a better match between the CT and the US images, reducing the differences to sub-millimeter agreement. Fifteen clinical cases of prostate cancer patients were also investigated: the SOS corrections of prostate centroids were on average +3.1 mm (max + 4.9 mm-min + 1.3 mm). This is in excellent agreement with reports in the literature on differences between measured prostate positions by US and other techniques, where often the discrepancy was attributed to other causes.

  7. Z-Contrast STEM Imaging and Ab-Initio Calculations of Grain Boundaries in SrTiO

    SciTech Connect

    Kim, M.; Browning, N.D.; Pennyscook, S.J.; Sohlberg, K.; Pantelides, S.T.

    1999-11-29

    The understanding of electrical properties of grain boundaries in perovskites is essential for their application to capacitors, varistors and positive-temperature coefficient resistors. The origin of the electrical activity is generally attributed to the existence of charged defects in grain boundaries, usually assumed to be impurities, which set up a double Schottky barrier as they are screened by dopants in the adjacent bulk crystal. Microscopic understanding of the origin of the grain boundary charge, however, has not been achieved. It is not known yet if the charged grain boundary states are an intrinsic property of a stoichiometric grain boundary, arise from nonstoichiometry, or are caused by impurities. Here, the relation between atomic structure and electronic properties is studied by combining experiment with ab-initio calculations. The starting structures for theoretical calculations were obtained from Z-contrast images combined with electron energy loss spectroscopy to res olve the dislocation Core structures comprising the boundary. Dislocation core reconstructions are typical of all grain boundaries so far observed in this material. They avoid like-ion repulsion, and provide alternative sites for cation occupation in the grain boundaries. Optimized atomic positions are found by total energy calculations. Calculated differences in vacancy formation energies between the grain boundaries and the bulk suggest that vacancy segregation can account for the postulated grain boundary charge.

  8. Direct imaging of the atomic structure and chemistry of defects and interfaces by Z-contrast STEM (scanning transmission electron microscopy)

    SciTech Connect

    Pennycook, S.J.; Chisholm, M.F.; Jesson, D.E.; Norton, D.P.; McCamy, J.W.; Lowndes, D.H.

    1990-02-01

    Z-contrast scanning transmission electron microscopy (STEM) is a fundamentally new approach to high-resolution imaging which provides unambiguous, compositionally sensitive images on the atomic scale. Such images are intuitively interpretable, even in thick regions of the sample, tremendously simplifying determination of the structure and chemistry of defects and interfaces. To illustrate this, examples are presented of commonly observed planar defects in laser-ablated thin films of YBa{sub 2}Cu{sub 3}O{sub 7-x}. Film/substrate interfaces are shown to be chemically diffuse on the atomic scale and steps or undulations in the substrate need not result in defects in the film. Low-angle grain boundaries are found to be chemically clean, the drastic reductions in critical currents with tilt angle being due to the array of intrinsic structural defects comprising the boundary. 20 refs., 10 figs.

  9. Aberration correction past and present.

    PubMed

    Hawkes, P W

    2009-09-28

    Electron lenses are extremely poor: if glass lenses were as bad, we should see as well with the naked eye as with a microscope! The demonstration by Otto Scherzer in 1936 that skillful lens design could never eliminate the spherical and chromatic aberrations of rotationally symmetric electron lenses was therefore most unwelcome and the other great electron optician of those years, Walter Glaser, never ceased striving to find a loophole in Scherzer's proof. In the wartime and early post-war years, the first proposals for correcting C(s) were made and in 1947, in a second milestone paper, Scherzer listed these and other ways of correcting lenses; soon after, Dennis Gabor invented holography for the same purpose. These approaches will be briefly summarized and the work that led to the successful implementation of quadupole-octopole and sextupole correctors in the 1990 s will be analysed. In conclusion, the elegant role of image algebra in describing image formation and processing and, above all, in developing new methods will be mentioned. PMID:19687058

  10. Optical advantages of astigmatic aberration corrected heliostats

    NASA Astrophysics Data System (ADS)

    van Rooyen, De Wet; Schöttl, Peter; Bern, Gregor; Heimsath, Anna; Nitz, Peter

    2016-05-01

    Astigmatic aberration corrected heliostats adapt their shape in dependence of the incidence angle of the sun on the heliostat. Simulations show that this optical correction leads to a higher concentration ratio at the target and thus in a decrease in required receiver aperture in particular for smaller heliostat fields.

  11. Lesion generation through ribs using histotripsy therapy without aberration correction.

    PubMed

    Kim, Yohan; Wang, Tzu-Yin; Xu, Zhen; Cain, Charles A

    2011-11-01

    This study investigates the feasibility of using high-intensity pulsed therapeutic ultrasound, or histotripsy, to non-invasively generate lesions through the ribs. Histotripsy therapy mechanically ablates tissue through the generation of a cavitation bubble cloud, which occurs when the focal pressure exceeds a certain threshold. We hypothesize that histotripsy can generate precise lesions through the ribs without aberration correction if the main lobe retains its shape and exceeds the cavitation initiation threshold and the secondary lobes remain below the threshold. To test this hypothesis, a 750-kHz focused transducer was used to generate lesions in tissue-mimicking phantoms with and without the presence of rib aberrators. In all cases, 8000 pulses with 16 to 18 MPa peak rarefactional pressure at a repetition frequency of 100 Hz were applied without aberration correction. Despite the high secondary lobes introduced by the aberrators, high-speed imaging showed that bubble clouds were generated exclusively at the focus, resulting in well-confined lesions with comparable dimensions. Collateral damage from secondary lobes was negligible, caused by single bubbles that failed to form a cloud. These results support our hypothesis, suggesting that histotripsy has a high tolerance for aberrated fields and can generate confined focal lesions through rib obstacles without aberration correction.

  12. High resolution structural and compositional mapping of the SrTiO3/LaFeO3 interface using chromatic aberration corrected energy filtered imaging

    NASA Astrophysics Data System (ADS)

    Kabius, Bernd; Houben, Lothar; Dwyer, Christian; Colby, Robert; Chambers, Scott A.; Dunin-Borkowski, Rafal

    2014-03-01

    Interfaces between insulating polar perovskites have demonstrated a wealth of electronic and magnetic properties. Understanding and predicting the properties of a specific interface requires atomic level knowledge of interface structure and chemistry. Electron microscopy is capable of this task, and has been frequently applied to oxide interfaces using a combination of high-angle angular dark field scanning transmission electron microscopy (HAADF-STEM) and electron energy-loss spectroscopy (EELS). Energy-filtered TEM (EFTEM) captures a full image for a given energy losses, allowing a larger field of view than typical for STEM-EELS in far less time. However, EFTEM has not, to date, demonstrated the spatial resolution of STEM-EELS due to the limits set by chromatic aberration Cc. This study of LaFeO3/SrTiO3 demonstrates that Cc correction enhances the resolution of EFTEM for elemental mapping, allowing a unit cell-by-unit cell analysis of the concentration gradients across the SrTiO3/LaFeO3 interface. The charge distribution at the interface will be discussed. The research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory

  13. Conformal dome aberration correction by designing the inner surface

    NASA Astrophysics Data System (ADS)

    Zhang, Wang; Chen, Shouqian; Fan, Zhigang

    2016-12-01

    The ray transmission models of optical domes were established, and the characteristics of the rays while passing through a hemispherical dome and a conformal dome were comparatively analysed. Acquiring the minimum deviated angles from the inner surface of the conformal dome was then determined to be the designing goal for reducing the dynamic aberrations. Based on this, the inner surface of the conformal dome was optimized and thus, the dynamic aberrations were reduced. Finally, a completely cooled conformal optical system was designed. The results show that the optical system have produced good imaging quality within all the fields of regard, which further illustrates that designing the inner surface of a conformal dome is an effective method for aberration correction.

  14. Seeing Inside Materials by Aberration-Corrected Electron Microscopy

    SciTech Connect

    Pennycook, Stephen J

    2011-01-01

    The recent successful correction of lens aberrations in the electron microscope has improved resolution by more than a factor of two in just a few years, bringing many benefits for the study of materials. These benefits extend significantly beyond enhanced resolution alone. Aberration correction gives higher resolution by allowing the objective lens to have a wider aperture, which also results in a reduced depth of field. This effect can be used to only focus specific sections inside materials for the first time. In this contribution we describe recent results exploiting this capability. Additionally, we show how combining the microscopy data with first-principles theory gives new insights into materials properties. We cover two applications, both involving heavy atoms in a lighter host. The first shows how single Hf atoms can be mapped in three dimensions inside the 1 nm-wide SiO2 region of a high dielectric constant device structure, and how a link to macroscopic device properties results through theoretical calculations. The second example is from the field of nanoscience, where individual Au atoms are imaged inside Si nanowires grown by a vapor-liquid-solid mechanism. The majority of Au atoms are probably injected by the highly energetic electron beam. However, their observed sites and atomic configurations represent at least meta-stable configurations and match well to results from density functional calculations.

  15. Aberration correction by maximizing generalized sharpness metrics.

    PubMed

    Fienup, J R; Miller, J J

    2003-04-01

    The technique of maximizing sharpness metrics has been used to estimate and compensate for aberrations with adaptive optics, to correct phase errors in synthetic-aperture radar, and to restore images. The largest class of sharpness metrics is the sum over a nonlinear point transformation of the image intensity. How the second derivative of the point nonlinearity varies with image intensity determines the effects of various metrics on the imagery. Some metrics emphasize making shadows darker, and other emphasize making bright points brighter. One can determine the image content needed to pick the best metric by computing the statistics of the image autocorrelation or of the Fourier magnitude, either of which is independent of the phase error. Computationally efficient, closed-form expressions for the gradient make possible efficient search algorithms to maximize sharpness.

  16. Direct observation of atomic columns in a Bi-2223 polycrystal by aberration-corrected STEM using a low accelerating voltage

    NASA Astrophysics Data System (ADS)

    Nagai, Takuro; Haruta, Mitsutaka; Kikuchi, Masashi; Zhang, Weizhu; Takeguchi, Masaki; Kimoto, Koji

    2014-05-01

    Aberration correction in scanning transmission electron microscopy (STEM) enables an atomic-scale probe size of ˜0.1 nm at a low accelerating voltage of 80 kV that avoids knock-on damage in materials including light elements such as oxygen. We used this advanced method of microscopy to directly observe atomic columns in a (Bi,Pb)2Sr2Ca2Cu3O10+δ (Bi-2223) superconducting wire produced by a powder-in-tube method. Using the atomic-number (Z) contrast mechanism, incoherent high-angle annular dark-field (HAADF) imaging clearly showed the atomic columns. Atomic displacements toward the boundary with a maximum magnitude of ˜0.26 nm enable each atomic layer to be continuous at edge grain boundaries (EGBs). The grains tend to be terminated with deficient (Bi,Pb)-O single layers at c-axis twist boundaries (TWBs) and small-angle asymmetrical tilt boundaries (ATBs); a quantitative HAADF analysis showed that the occupancies of the (Bi,Pb) sites around these boundaries are ˜0.66 and ˜0.72, respectively. Electron energy-loss spectroscopy (EELS) mapping successfully visualized atomic columns in the half-unit cell intergrowth of (Bi,Pb)2Sr2CaCu2O8+δ (Bi-2212) and (Bi,Pb)2Sr2Ca3Cu4O12+δ (Bi-2234) phases. Furthermore, the HAADF analysis indicated that the occupancy of the (Bi,Pb) sites is modulated between ˜0.88 and 1.0 along the diagonal direction of the primitive perovskite cell with the same period as the structural modulation.

  17. Numerical spherical aberration correction method using spatial light modulator under deep-part fluorescence observation

    NASA Astrophysics Data System (ADS)

    Takiguchi, Yu; Takamoto, Hisayoshi; Kanada, Masamitsu; Inoue, Takashi; Matsumoto, Naoya; Terakawa, Susumu

    2014-03-01

    We have developed a confocal fluorescence laser scanning microscopy (CFLSM) incorporating a liquid crystal on silicon spatial light modulator (LCOS-SLM). To achieve high-resolution and high-contrast imaging for deeper part of the tissue with CFLSM, high numerical aperture objective lenses are required to tightly focus excitation light to meet Rayleigh limit(criterion) for the specimens. However, mismatch of refractive index at the boundary of interfacing materials, such as atmosphere, glass cover, and biological tissues, causes spherical aberration. Recently, we proposed a numerical method for correcting spherical aberration. In this method a pre-distorted wavefront pattern for aberration correction is calculated by ray tracing from a hypothetical focal point inside a specimen to the pupil plane. The resulting microscope can correct such spherical aberration. We observed 6.0μm fluorescent micro-beads dispersed three-dimensionally in agarose gel to confirm effectiveness of aberration correction. We reconstructed a three-dimensional image by taking 20 images by changing the depth with 1 μm interval and stacking them. It was apparent that the longitudinal/depth resolution was improved and that the intensity of fluorescence image was increased with aberration correction. While this method is applicable to other laser scanning microscopes, it has potential to enhance the signals for various super-resolution microscopic techniques, such as stimulated- emission-depletion (STED) fluorescence microscopy.

  18. Variable zoom system with aberration correction capability

    NASA Astrophysics Data System (ADS)

    Lu, Yang; Stockbridge, Christopher R.; Hoffman, Samuel M.; Bifano, Thomas G.

    2012-07-01

    We describe experiments conducted with two deformable mirrors (DMs) at fixed locations in an optical microscope imaging system. In this configuration, the DM shapes are controlled to provide 2.5× zoom capability, to allow dynamic focus control and to compensate for aberrations of the fixed optical components. Zoom is achieved by simultaneously adjusting focal lengths of the two DMs, which are inserted between an infinity-corrected microscope objective and a tube lens. Image quality is measured using contrast modulation, and performance of the system is quantified, demonstrating an improved point spread function in the adaptively compensated system.

  19. Nanowire growth kinetics in aberration corrected environmental transmission electron microscopy

    DOE PAGES

    Chou, Yi -Chia; Panciera, Federico; Reuter, Mark C.; Stach, Eric A.; Ross, Frances M.

    2016-03-15

    Here, we visualize atomic level dynamics during Si nanowire growth using aberration corrected environmental transmission electron microscopy, and compare with lower pressure results from ultra-high vacuum microscopy. We discuss the importance of higher pressure observations for understanding growth mechanisms and describe protocols to minimize effects of the higher pressure background gas.

  20. Towards aberration correction of transcranial ultrasound using acoustic droplet vaporization.

    PubMed

    Haworth, Kevin J; Fowlkes, J Brian; Carson, Paul L; Kripfgans, Oliver D

    2008-03-01

    We report on the first experiments demonstrating the transcranial acoustic formation of stable gas bubbles that can be used for transcranial ultrasound aberration correction. It is demonstrated that the gas bubbles can be formed transcranially by phase-transitioning single, superheated, micron-size, liquid dodecafluoropentane droplets with ultrasound, a process known as acoustic droplet vaporization (ADV). ADV was performed at 550 kHz, where the skull is less attenuating and aberrating, allowing for higher-amplitudes to be reached at the focus. Additionally, it is demonstrated that time-reversal focusing at 1 MHz can be used to correct for transcranial aberrations with a single gas bubble acting as a point beacon. Aberration correction was performed using a synthetic aperture approach and verified by the realignment of the scattered waveforms. Under the conditions described below, time-reversal aberration correction using gas bubbles resulted in a gain of 1.9 +/- 0.3 in an introduced focusing factor. This is a small fraction of the gain anticipated from complete transmit-receive of a fully-populated two-dimensional array with sub-wavelength elements. (E-mail: khaworth@umich.edu).

  1. The three-dimensional point spread function of aberration-corrected scanning transmission electron microscopy.

    PubMed

    Lupini, Andrew R; de Jonge, Niels

    2011-10-01

    Aberration correction reduces the depth of field in scanning transmission electron microscopy (STEM) and thus allows three-dimensional (3D) imaging by depth sectioning. This imaging mode offers the potential for sub-Ångstrom lateral resolution and nanometer-scale depth sensitivity. For biological samples, which may be many microns across and where high lateral resolution may not always be needed, optimizing the depth resolution even at the expense of lateral resolution may be desired, aiming to image through thick specimens. Although there has been extensive work examining and optimizing the probe formation in two dimensions, there is less known about the probe shape along the optical axis. Here the probe shape is examined in three dimensions in an attempt to better understand the depth resolution in this mode. Examples are presented of how aberrations change the probe shape in three dimensions, and it is found that off-axial aberrations may need to be considered for focal series of large areas. It is shown that oversized or annular apertures theoretically improve the vertical resolution for 3D imaging of nanoparticles. When imaging nanoparticles of several nanometer size, regular STEM can thereby be optimized such that the vertical full-width at half-maximum approaches that of the aberration-corrected STEM with a standard aperture.

  2. Intrinsic instability of aberration-corrected electron microscopes.

    PubMed

    Schramm, S M; van der Molen, S J; Tromp, R M

    2012-10-19

    Aberration-corrected microscopes with subatomic resolution will impact broad areas of science and technology. However, the experimentally observed lifetime of the corrected state is just a few minutes. Here we show that the corrected state is intrinsically unstable; the higher its quality, the more unstable it is. Analyzing the contrast transfer function near optimum correction, we define an "instability budget" which allows a rational trade-off between resolution and stability. Unless control systems are developed to overcome these challenges, intrinsic instability poses a fundamental limit to the resolution practically achievable in the electron microscope.

  3. Studying Atomic Structures by Aberration-Corrected Transmission Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Urban, Knut W.

    2008-07-01

    Seventy-five years after its invention, transmission electron microscopy has taken a great step forward with the introduction of aberration-corrected electron optics. An entirely new generation of instruments enables studies in condensed-matter physics and materials science to be performed at atomic-scale resolution. These new possibilities are meeting the growing demand of nanosciences and nanotechnology for the atomic-scale characterization of materials, nanosynthesized products and devices, and the validation of expected functions. Equipped with electron-energy filters and electron-energy loss spectrometers, the new instruments allow studies not only of structure but also of elemental composition and chemical bonding. The energy resolution is about 100 milli electron volts, and the accuracy of spatial measurements has reached a few picometers. However, understanding the results is generally not straightforward and only possible with extensive quantum-mechanical computer calculations.

  4. Studying atomic structures by aberration-corrected transmission electron microscopy.

    PubMed

    Urban, Knut W

    2008-07-25

    Seventy-five years after its invention, transmission electron microscopy has taken a great step forward with the introduction of aberration-corrected electron optics. An entirely new generation of instruments enables studies in condensed-matter physics and materials science to be performed at atomic-scale resolution. These new possibilities are meeting the growing demand of nanosciences and nanotechnology for the atomic-scale characterization of materials, nanosynthesized products and devices, and the validation of expected functions. Equipped with electron-energy filters and electron-energy-loss spectrometers, the new instruments allow studies not only of structure but also of elemental composition and chemical bonding. The energy resolution is about 100 milli-electron volts, and the accuracy of spatial measurements has reached a few picometers. However, understanding the results is generally not straightforward and only possible with extensive quantum-mechanical computer calculations. PMID:18653874

  5. Spherical Aberration Corrections for the Electrostatic Gridded Lens

    SciTech Connect

    Pikin,A.

    2008-05-01

    Two methods of spherical aberration corrections of an electrostatic gridded lens have been studied with ray tracing simulations. Both methods are based on modifying electrostatic field on the periphery of the lens. In a simplest case such modification is done by extending the part of the grid support on its radial periphery in axial direction. In alternative method the electric field on the radial periphery of the lens is modified by applying an optimum voltage on an electrically isolated correcting electrode. It was demonstrated, that for a given focal length the voltage on this lens can be optimized for minimum aberration The performance of lenses is presented as a lens contribution to the beam RMS normalized emittance.

  6. Holographic optical system for aberration corrections in laser Doppler velocimetry

    NASA Technical Reports Server (NTRS)

    Kim, R. C.; Case, S. K.; Schock, H. J.

    1985-01-01

    An optical system containing multifaceted holographic optical elements (HOEs) has been developed to correct for aberrations introduced by nonflat windows in laser Doppler velocimetry. The multifacet aberration correction approach makes it possible to record on one plate many sets of adjacent HOEs that address different measurement volume locations. By using 5-mm-diameter facets, it is practical to place 10-20 sets of holograms on one 10 x 12.5-cm plate, so that the procedure of moving the entire optical system to examine different locations may not be necessary. The holograms are recorded in dichromated gelatin and therefore are nonabsorptive and suitable for use with high-power argon laser beams. Low f-number optics coupled with a 90-percent efficient distortion-correcting hologram in the collection side of the system yield high optical efficiency.

  7. Model-based sensor-less wavefront aberration correction in optical coherence tomography.

    PubMed

    Verstraete, Hans R G W; Wahls, Sander; Kalkman, Jeroen; Verhaegen, Michel

    2015-12-15

    Several sensor-less wavefront aberration correction methods that correct nonlinear wavefront aberrations by maximizing the optical coherence tomography (OCT) signal are tested on an OCT setup. A conventional coordinate search method is compared to two model-based optimization methods. The first model-based method takes advantage of the well-known optimization algorithm (NEWUOA) and utilizes a quadratic model. The second model-based method (DONE) is new and utilizes a random multidimensional Fourier-basis expansion. The model-based algorithms achieve lower wavefront errors with up to ten times fewer measurements. Furthermore, the newly proposed DONE method outperforms the NEWUOA method significantly. The DONE algorithm is tested on OCT images and shows a significantly improved image quality. PMID:26670496

  8. Depth Sectioning with the Aberration-Corrected Scanning Transmission Electron Microscope

    SciTech Connect

    Borisevich, Albina Y; Lupini, Andrew R; Pennycook, Stephen J

    2006-01-01

    The ability to correct the aberrations of the probe-forming lens in the scanning transmission electron microscope provides not only a significant improvement in transverse resolution but in addition brings depth resolution at the nanometer scale. Aberration correction therefore opens up the possibility of 3D imaging by optical sectioning. Here we develop a definition for the depth resolution for scanning transmission electron microscope depth sectioning and present initial results from this method. Objects such as catalytic metal clusters and single atoms on various support materials are imaged in three dimensions with a resolution of several nanometers. Effective focal depth is determined by statistical analysis and the contributing factors are discussed. Finally, current challenges and future capabilities available through new instruments are discussed.

  9. In vivo transcostal histotripsy therapy without aberration correction

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Vlaisavljevich, E.; Owens, G. E.; Allen, S. P.; Cain, C. A.; Xu, Z.

    2014-06-01

    This study investigates the in vivo therapeutic capabilities of transcostal histotripsy without using aberration correction mechanisms and its thermal impact on overlying tissues. Non-invasive liver treatments were conducted in eight pigs, with four lesions generated through transcostal windows with full ribcage obstruction and four lesions created through transabdominal windows without rib coverage. Treatments were performed by a 750 kHz focused transducer using 5 cycle pulses at 200 Hz PRF, with estimated in situ peak negative pressures of 13-17 MPa. Temperatures on overlying tissues including the ribs were measured with needle thermocouples inserted superficially beneath the skin. Treatments of approximately 40 min were applied, allowing overlying tissue temperatures to reach saturation. Lesions yielded statistically comparable ablation volumes of 3.6 ± 1.7 cm3 and 4.5 ± 2.0 cm3 in transcostal and transabdominal treatments, respectively. The average temperature increase observed in transcostal treatments was 3.9 ± 2.1 °C, while transabdominal treatments showed an increase of 1.7 ± 1.3 °C. No damage was seen on the ribcage or other overlying tissues. These results indicate that histotripsy can achieve effective treatment through the ribcage in vivo without requiring correction mechanisms, while inducing no substantial thermal effects or damage to overlying tissues. Such capabilities could benefit several non-invasive therapy applications involving transcostal treatment windows.

  10. Phase aberration correction by correlation in digital holographic adaptive optics

    PubMed Central

    Liu, Changgeng; Yu, Xiao; Kim, Myung K.

    2013-01-01

    We present a phase aberration correction method based on the correlation between the complex full-field and guide-star holograms in the context of digital holographic adaptive optics (DHAO). Removal of a global quadratic phase term before the correlation operation plays an important role in the correction. Correlation operation can remove the phase aberration at the entrance pupil plane and automatically refocus the corrected optical field. Except for the assumption that most aberrations lie at or close to the entrance pupil, the presented method does not impose any other constraints on the optical systems. Thus, it greatly enhances the flexibility of the optical design for DHAO systems in vision science and microscopy. Theoretical studies show that the previously proposed Fourier transform DHAO (FTDHAO) is just a special case of this general correction method, where the global quadratic phase term and a defocus term disappear. Hence, this correction method realizes the generalization of FTDHAO into arbitrary DHAO systems. The effectiveness and robustness of this method are demonstrated by simulations and experiments. PMID:23669707

  11. Design of macro-filter-lens with simultaneous chromatic and geometric aberration correction.

    PubMed

    Prasad, Dilip K; Brown, Michael S

    2014-01-01

    A macro-filter-lens design that can correct for chromatic and geometric aberrations simultaneously while providing for a long focal length is presented. The filter is easy to fabricate since it involves two spherical surfaces and a planar surface. Chromatic aberration correction is achieved by making all the rays travel the same optical distance inside the filter element (negative meniscus). Geometric aberration is corrected for by the lens element (plano-convex), which makes the output rays parallel to the optic axis. This macro-filter-lens design does not need additional macro lenses and it provides an inexpensive and optically good (aberration compensated) solution for macro imaging of objects not placed close to the camera.

  12. Coalescence and sintering of Pt nanoparticles: in situ observation by aberration-corrected HAADF STEM.

    PubMed

    Asoro, M A; Kovar, D; Shao-Horn, Y; Allard, L F; Ferreira, P J

    2010-01-15

    An aberration-corrected JEOL 2200FS scanning-transmission electron microscope (STEM), equipped with a high-angle annular dark-field detector (HAADF), is used to monitor the coalescence and sintering of Pt nanoparticles with an average diameter of 2.8 nm. This in situ STEM capability is combined with an analysis methodology that together allows direct measurements of mass transport phenomena that are important in understanding how particle size influences coalescence and sintering at the nanoscale. To demonstrate the feasibility of this methodology, the surface diffusivity is determined from measurements obtained from STEM images acquired during the initial stages of sintering. The measured surface diffusivities are in reasonable agreement with measurements made on the surface of nanoparticles, using other techniques. In addition, the grain boundary mobility is determined from measurements made during the latter stages of sintering. PMID:19955618

  13. Coalescence and sintering of Pt nanoparticles: in situ observation by aberration-corrected HAADF STEM

    NASA Astrophysics Data System (ADS)

    Asoro, M. A.; Kovar, D.; Shao-Horn, Y.; Allard, L. F.; Ferreira, P. J.

    2010-01-01

    An aberration-corrected JEOL 2200FS scanning-transmission electron microscope (STEM), equipped with a high-angle annular dark-field detector (HAADF), is used to monitor the coalescence and sintering of Pt nanoparticles with an average diameter of 2.8 nm. This in situ STEM capability is combined with an analysis methodology that together allows direct measurements of mass transport phenomena that are important in understanding how particle size influences coalescence and sintering at the nanoscale. To demonstrate the feasibility of this methodology, the surface diffusivity is determined from measurements obtained from STEM images acquired during the initial stages of sintering. The measured surface diffusivities are in reasonable agreement with measurements made on the surface of nanoparticles, using other techniques. In addition, the grain boundary mobility is determined from measurements made during the latter stages of sintering.

  14. Transcranial passive acoustic mapping with hemispherical sparse arrays using CT-based skull-specific aberration corrections: a simulation study.

    PubMed

    Jones, Ryan M; O'Reilly, Meaghan A; Hynynen, Kullervo

    2013-07-21

    The feasibility of transcranial passive acoustic mapping with hemispherical sparse arrays (30 cm diameter, 16 to 1372 elements, 2.48 mm receiver diameter) using CT-based aberration corrections was investigated via numerical simulations. A multi-layered ray acoustic transcranial ultrasound propagation model based on CT-derived skull morphology was developed. By incorporating skull-specific aberration corrections into a conventional passive beamforming algorithm (Norton and Won 2000 IEEE Trans. Geosci. Remote Sens. 38 1337-43), simulated acoustic source fields representing the emissions from acoustically-stimulated microbubbles were spatially mapped through three digitized human skulls, with the transskull reconstructions closely matching the water-path control images. Image quality was quantified based on main lobe beamwidths, peak sidelobe ratio, and image signal-to-noise ratio. The effects on the resulting image quality of the source's emission frequency and location within the skull cavity, the array sparsity and element configuration, the receiver element sensitivity, and the specific skull morphology were all investigated. The system's resolution capabilities were also estimated for various degrees of array sparsity. Passive imaging of acoustic sources through an intact skull was shown possible with sparse hemispherical imaging arrays. This technique may be useful for the monitoring and control of transcranial focused ultrasound (FUS) treatments, particularly non-thermal, cavitation-mediated applications such as FUS-induced blood-brain barrier disruption or sonothrombolysis, for which no real-time monitoring techniques currently exist.

  15. Transcranial passive acoustic mapping with hemispherical sparse arrays using CT-based skull-specific aberration corrections: a simulation study

    PubMed Central

    Jones, Ryan M.; O’Reilly, Meaghan A.; Hynynen, Kullervo

    2013-01-01

    The feasibility of transcranial passive acoustic mapping with hemispherical sparse arrays (30 cm diameter, 16 to 1372 elements, 2.48 mm receiver diameter) using CT-based aberration corrections was investigated via numerical simulations. A multi-layered ray acoustic transcranial ultrasound propagation model based on CT-derived skull morphology was developed. By incorporating skull-specific aberration corrections into a conventional passive beamforming algorithm (Norton and Won 2000 IEEE Trans. Geosci. Remote Sens. 38 1337–43), simulated acoustic source fields representing the emissions from acoustically-stimulated microbubbles were spatially mapped through three digitized human skulls, with the transskull reconstructions closely matching the water-path control images. Image quality was quantified based on main lobe beamwidths, peak sidelobe ratio, and image signal-to-noise ratio. The effects on the resulting image quality of the source’s emission frequency and location within the skull cavity, the array sparsity and element configuration, the receiver element sensitivity, and the specific skull morphology were all investigated. The system’s resolution capabilities were also estimated for various degrees of array sparsity. Passive imaging of acoustic sources through an intact skull was shown possible with sparse hemispherical imaging arrays. This technique may be useful for the monitoring and control of transcranial focused ultrasound (FUS) treatments, particularly non-thermal, cavitation-mediated applications such as FUS-induced blood-brain barrier disruption or sonothrombolysis, for which no real-time monitoring technique currently exists. PMID:23807573

  16. Transcranial passive acoustic mapping with hemispherical sparse arrays using CT-based skull-specific aberration corrections: a simulation study

    NASA Astrophysics Data System (ADS)

    Jones, Ryan M.; O'Reilly, Meaghan A.; Hynynen, Kullervo

    2013-07-01

    The feasibility of transcranial passive acoustic mapping with hemispherical sparse arrays (30 cm diameter, 16 to 1372 elements, 2.48 mm receiver diameter) using CT-based aberration corrections was investigated via numerical simulations. A multi-layered ray acoustic transcranial ultrasound propagation model based on CT-derived skull morphology was developed. By incorporating skull-specific aberration corrections into a conventional passive beamforming algorithm (Norton and Won 2000 IEEE Trans. Geosci. Remote Sens. 38 1337-43), simulated acoustic source fields representing the emissions from acoustically-stimulated microbubbles were spatially mapped through three digitized human skulls, with the transskull reconstructions closely matching the water-path control images. Image quality was quantified based on main lobe beamwidths, peak sidelobe ratio, and image signal-to-noise ratio. The effects on the resulting image quality of the source’s emission frequency and location within the skull cavity, the array sparsity and element configuration, the receiver element sensitivity, and the specific skull morphology were all investigated. The system’s resolution capabilities were also estimated for various degrees of array sparsity. Passive imaging of acoustic sources through an intact skull was shown possible with sparse hemispherical imaging arrays. This technique may be useful for the monitoring and control of transcranial focused ultrasound (FUS) treatments, particularly non-thermal, cavitation-mediated applications such as FUS-induced blood-brain barrier disruption or sonothrombolysis, for which no real-time monitoring techniques currently exist.

  17. Transcranial phase aberration correction using beam simulations and MR-ARFI

    SciTech Connect

    Vyas, Urvi Kaye, Elena; Pauly, Kim Butts

    2014-03-15

    Purpose: Transcranial magnetic resonance-guided focused ultrasound surgery is a noninvasive technique for causing selective tissue necrosis. Variations in density, thickness, and shape of the skull cause aberrations in the location and shape of the focal zone. In this paper, the authors propose a hybrid simulation-MR-ARFI technique to achieve aberration correction for transcranial MR-guided focused ultrasound surgery. The technique uses ultrasound beam propagation simulations with MR Acoustic Radiation Force Imaging (MR-ARFI) to correct skull-caused phase aberrations. Methods: Skull-based numerical aberrations were obtained from a MR-guided focused ultrasound patient treatment and were added to all elements of the InSightec conformal bone focused ultrasound surgery transducer during transmission. In the first experiment, the 1024 aberrations derived from a human skull were condensed into 16 aberrations by averaging over the transducer area of 64 elements. In the second experiment, all 1024 aberrations were applied to the transducer. The aberrated MR-ARFI images were used in the hybrid simulation-MR-ARFI technique to find 16 estimated aberrations. These estimated aberrations were subtracted from the original aberrations to result in the corrected images. Each aberration experiment (16-aberration and 1024-aberration) was repeated three times. Results: The corrected MR-ARFI image was compared to the aberrated image and the ideal image (image with zero aberrations) for each experiment. The hybrid simulation-MR-ARFI technique resulted in an average increase in focal MR-ARFI phase of 44% for the 16-aberration case and 52% for the 1024-aberration case, and recovered 83% and 39% of the ideal MR-ARFI phase for the 16-aberrations and 1024-aberration case, respectively. Conclusions: Using one MR-ARFI image and noa priori information about the applied phase aberrations, the hybrid simulation-MR-ARFI technique improved the maximum MR-ARFI phase of the beam's focus.

  18. Bayesian-based aberration correction and numerical diffraction for improved lensfree on-chip microscopy of biological specimens.

    PubMed

    Wong, Alexander; Kazemzadeh, Farnoud; Jin, Chao; Wang, Xiao Yu

    2015-05-15

    Lensfree on-chip microscopy is an emerging imaging technique that can be used to visualize and study biological specimens without the need for imaging lens systems. Important issues that can limit the performance of lensfree on-chip microscopy include interferometric aberrations, acquisition noise, and image reconstruction artifacts. In this study, we introduce a Bayesian-based method for performing aberration correction and numerical diffraction that accounts for all three of these issues to improve the effective numerical aperture (NA) and signal-to-noise ratio (SNR) of the reconstructed microscopic image. The proposed method was experimentally validated using the USAF resolution target as well as real waterborne Anabaena flos-aquae samples, demonstrating improvements in NA by ∼25% over the standard method, and improvements in SNR of 2.8 and 8.2 dB in the reconstructed image when compared to the reconstructed images produced using the standard method and a maximum likelihood estimation method, respectively.

  19. Probing structures of nanomaterials using advanced electron microscopy methods, including aberration-corrected electron microscopy at the Angstrom scale.

    PubMed

    Gai, Pratibha L; Yoshida, Kenta; Shute, Carla; Jia, Xiaoting; Walsh, Michael; Ward, Michael; Dresselhaus, Mildred S; Weertman, Julia R; Boyes, Edward D

    2011-07-01

    Structural and compositional studies of nanomaterials of technological importance have been carried out using advanced electron microscopy methods, including aberration-corrected transmission electron microscopy (AC-TEM), AC-high angle annular dark field scanning TEM (AC-HAADF-STEM), AC-energy filtered TEM, electron-stimulated energy dispersive spectroscopy in the AC-(S)TEM and high-resolution TEM (HRTEM) with scanning tunneling microscopy (STM) holder. The AC-EM data reveal improvements in resolution and minimization in image delocalization. A JEOL 2200FS double-AC field emission gun TEM/STEM operating at 200 kV in the Nanocentre at the University of York has been used to image single metal atoms on crystalline supports in catalysts, grain boundaries in nanotwinned metals, and nanostructures of tetrapods. Joule heating studies using HRTEM integrated with an STM holder reveal in situ crystallization and edge reconstruction in graphene. Real-time in situ AC-HAADF-STEM studies at elevated temperatures are described. Dynamic in-column energy filtering in an AC environment provides an integral new approach to perform dynamic in situ studies with aberration correction. The new results presented here open up striking new opportunities for atomic scale studies of nanomaterials and indicate future development directions.

  20. Evolution of gold structure during thermal treatment of Au/FeOx catalysts revealed by aberration-corrected electron microscopy.

    PubMed

    Allard, Lawrence F; Borisevich, Albina; Deng, Weiling; Si, Rui; Flytzani-Stephanopoulos, Maria; Overbury, Steven H

    2009-06-01

    High-resolution aberration-corrected electron microscopy was performed on a series of catalysts derived from a parent material, 2 at.% Au/Fe(2)O(3) (WGC ref. no. 60C), prepared by co-precipitation and calcined in air at 400 degrees C, and a catalyst prepared by leaching surface gold from the parent catalyst and exposed to various treatments, including use in the water-gas shift reaction at 250 degrees C. Aberration-corrected JEOL 2200FS (JEOL USA, Peabody, MA) and Vacuum Generators HB-603U STEM instruments were used to image fresh, reduced, leached, used and re-oxidized catalyst samples. A new in situ heating technology (Protochips Inc., Raleigh, NC, USA), which permits full sub-Angström imaging resolution in the JEOL 2200FS was used to study the effects of temperature on the behavior of gold species. A remarkable stability of gold to redox treatments up to 400 degrees C, with atomic gold decorating step surfaces of iron oxide was identified. On heating the samples in vacuum to 700 degrees C, it was found that monodispersed gold began to sinter to form nanoparticles above 500 degrees C. Gold species internal to the iron oxide support material was shown to diffuse to the surface at elevated temperature, coalescing into discrete nanocrystals. The results demonstrate the value of in situ heating for understanding morphological changes in the catalyst with elevated temperature treatments.

  1. Interfacial atomic structure analysis at sub-angstrom resolution using aberration-corrected STEM

    NASA Astrophysics Data System (ADS)

    Hsiao, Chien-Nan; Kuo, Shou-Yi; Lai, Fang-I.; Chen, Wei-Chun

    2014-10-01

    The atomic structure of a SiGe/Si epitaxial interface grown via molecular beam epitaxy on a single crystal silicon substrate was investigated using an aberration-corrected scanning transmittance electron microscope equipped with a high-angle annular dark-field detector and an energy-dispersive spectrometer. The accuracy required for compensation of the various residual aberration coefficients to achieve sub-angstrom resolution with the electron optics system was also evaluated. It was found that the interfacial layer was composed of a silicon single crystal, connected coherently to epitaxial SiGe nanolaminates. In addition, the distance between the dumbbell structures of the Si and Ge atoms was approximately 0.136 nm at the SiGe/Si interface in the [110] orientation. The corresponding fast Fourier transform exhibited a sub-angstrom scale point resolution of 0.78 Å. Furthermore, the relative positions of the atoms in the chemical composition line scan signals could be directly interpreted from the corresponding incoherent high-angle annular dark-field image.

  2. High-resolution microspectrometer with an aberration-correcting planar grating.

    PubMed

    Grabarnik, Semen; Emadi, Arvin; Wu, Huaiwen; de Graaf, Ger; Wolffenbuttel, Reinoud F

    2008-12-01

    A concept for a highly miniaturized spectrometer featuring a two-component design is presented. The first component is a planar chip that integrates an input slit and aberration-correcting diffraction grating with an image sensor and is fabricated using microelectromechanical systems (MEMS) technologies. Due to the fabrication in a simple MEMS batch process the essential elements of the spectrometer are automatically aligned, and a low fabrication cost per device can be achieved. The second component is a spherical mirror, which is the only external part. The optimized grating structure compensates for aberrations within the spectrometer operating range, resulting in a diffraction-limited performance of the spectrometer optics. The prototype of the device has been fabricated and characterized. It takes a volume of 0.5 cm(3) and provides a FWHM spectral resolution of 0.7 nm over a 350 nm bandwidth from 420 nm to 770 nm combined with an etendue of 7.4x10(-5) mm(2) sr. PMID:19037373

  3. Sub-Angstrom Low Voltage Performance of a Monochromated, Aberration-Corrected Transmission Electron Microscope

    PubMed Central

    Bell, David C.; Russo, Christopher J.; Benner, Gerd

    2011-01-01

    Lowering the electron energy in the transmission electron microscope allows for a significant improvement in contrast of light elements, and reduces knock-on damage for most materials. If low-voltage electron microscopes are defined as those with accelerating voltages below 100 kV, the introduction of aberration correctors and monochromators to the electron microscope column enables Ångstrom-level resolution, which was previously reserved for higher voltage instruments. Decreasing electron energy has three important advantages: 1) knock-on damage is lower, which is critically important for sensitive materials such as graphene and carbon nanotubes; 2) cross sections for electron-energy-loss spectroscopy increase, improving signal-to-noise for chemical analysis; 3) elastic scattering cross sections increase, improving contrast in high-resolution, zero-loss images. The results presented indicate that decreasing the acceleration voltage from 200 kV to 80 kV in a monochromated, aberration-corrected microscope enhances the contrast while retaining sub-angstrom resolution. These improvements in low-voltage performance are expected to produce many new results and enable a wealth of new experiments in materials science. PMID:20598206

  4. Adaptive Optics Analysis of Visual Benefit with Higher-order Aberrations Correction of Human Eye - Poster Paper

    NASA Astrophysics Data System (ADS)

    Xue, Lixia; Dai, Yun; Rao, Xuejun; Wang, Cheng; Hu, Yiyun; Liu, Qian; Jiang, Wenhan

    2008-01-01

    Higher-order aberrations correction can improve visual performance of human eye to some extent. To evaluate how much visual benefit can be obtained with higher-order aberrations correction we developed an adaptive optics vision simulator (AOVS). Dynamic real time optimized modal compensation was used to implement various customized higher-order ocular aberrations correction strategies. The experimental results indicate that higher-order aberrations correction can improve visual performance of human eye comparing with only lower-order aberration correction but the improvement degree and higher-order aberration correction strategy are different from each individual. Some subjects can acquire great visual benefit when higher-order aberrations were corrected but some subjects acquire little visual benefit even though all higher-order aberrations were corrected. Therefore, relative to general lower-order aberrations correction strategy, customized higher-order aberrations correction strategy is needed to obtain optimal visual improvement for each individual. AOVS provides an effective tool for higher-order ocular aberrations optometry for customized ocular aberrations correction.

  5. Automated spherical aberration correction in scanning confocal microscopy

    NASA Astrophysics Data System (ADS)

    Yoo, H. W.; van Royen, M. E.; van Cappellen, W. A.; Houtsmuller, A. B.; Verhaegen, M.; Schitter, G.

    2014-12-01

    Mismatch between the refractive indexes of immersion media and glass coverslips introduces spherical aberrations in microscopes especially for high numerical aperture objectives. This contribution demonstrates an automated adjustment of the coverslip correction collar in scanning confocal microscopy to compensate for spherical aberrations due to coverslip thickness mismatch. With a motorized coverslip correction collar, the adjustment procedure consists of xz image scans, image processing, correction quality evaluation, the mismatch estimation, and eventually the optimal adjustment of the correction collar. For fast correction with less photodamage, coarse-fine Gaussian fitting algorithms are proposed and evaluated with various specimen for their estimation accuracy. The benefits of the proposed automated correction are demonstrated for various coverslips with biological specimens, showing the optimized resolution of the confocal microscope.

  6. 3-D stimulated emission depletion microscopy with programmable aberration correction.

    PubMed

    Lenz, Martin O; Sinclair, Hugo G; Savell, Alexander; Clegg, James H; Brown, Alice C N; Davis, Daniel M; Dunsby, Chris; Neil, Mark A A; French, Paul M W

    2014-01-01

    We present a stimulated emission depletion (STED) microscope that provides 3-D super resolution by simultaneous depletion using beams with both a helical phase profile for enhanced lateral resolution and an annular phase profile to enhance axial resolution. The 3-D depletion point spread function is realised using a single spatial light modulator that can also be programmed to compensate for aberrations in the microscope and the sample. We apply it to demonstrate the first 3-D super-resolved imaging of an immunological synapse between a Natural Killer cell and its target cell.

  7. Tomographic diffractive microscopy and multiview profilometry with flexible aberration correction.

    PubMed

    Liu, H; Bailleul, J; Simon, B; Debailleul, M; Colicchio, B; Haeberlé, O

    2014-02-01

    We have developed a tomographic diffractive microscope in reflection, which permits observation of sample surfaces with an improved lateral resolution, compared to a conventional holographic microscope. From the same set of data, high-precision measurements can be performed on the shape of the reflective surface by reconstructing the phase of the diffracted field. Doing so allows for several advantages compared to classical holographic interferometric measurements: improvement in lateral resolution, easier phase unwrapping, reduction of the coherent noise, combined with the high-longitudinal precision provided by interferometric phase measurements. We demonstrate these capabilities by imaging various test samples. PMID:24514193

  8. Identification of magnetic properties of few nm sized FePt crystalline particles by characterizing the intrinsic atom order using aberration corrected S/TEM.

    PubMed

    Biskupek, Johannes; Jinschek, Joerg R; Wiedwald, Ulf; Bendele, Markus; Han, Luyang; Ziemann, Paul; Kaiser, Ute

    2010-06-01

    Hard-magnetic nanomaterials like nanoparticles of FePt are of great interest because of their promising potential for data storage applications. The magnetic properties of FePt structures strongly differ whether the crystal phases are face centered cubic (fcc) or face centered tetragonal (fct). We evaluated aberration corrected HRTEM, electron diffraction and aberration corrected HAADF-STEM as methods to measure the chemical degree of order S that describes the ordering of Pt and Fe atoms within the crystals unit cells. S/TEM experiments are accompanied by image calculations. The findings are compared with results obtained from X-ray diffraction on a FePt film. Our results show that STEM is a reasonable fast approach over HRTEM and electron diffraction to locally determine the chemical degree of order S.

  9. Three-dimensional location of a single dopant with atomic precision by aberration-corrected scanning transmission electron microscopy.

    PubMed

    Ishikawa, Ryo; Lupini, Andrew R; Findlay, Scott D; Taniguchi, Takashi; Pennycook, Stephen J

    2014-01-01

    Materials properties, such as optical and electronic response, can be greatly enhanced by isolated single dopants. Determining the full three-dimensional single-dopant defect structure and spatial distribution is therefore critical to understanding and adequately tuning functional properties. Combining quantitative Z-contrast scanning transmission electron microscopy images with image simulations, we show the direct determination of the atomic-scale depth location of an optically active, single atom Ce dopant embedded within wurtzite-type AlN. The method represents a powerful new tool for reconstructing three-dimensional information from a single, two-dimensional image.

  10. A discussion of two wavefront aberration correction procedures.

    PubMed

    Steinberg, B D

    1992-10-01

    This review paper discusses the basic properties of two adaptive signal processing procedures for dealing with weak scattering in a phased array transducer system. A fundamental improvement in the lateral resolution of ultrasonic echo scanners will result if the weight vector of a large phased array transducer can be modified to account for distortion in the propagation medium. Lateral resolution in most tissue is limited to a few mm by wavefront-distortion-induced sound-speed variations. One important wavefront-distortion source is scattering from local speed variations within large and reasonably homogeneous tissue beds such as the liver. Scattering disperses some energy from the beam and perturbs the wavefront, thereby distorting the image and limiting the resolution to the scale of the distortion. Often, such scattering is weak, meaning that most of the energy in the beam is unscattered. The total field at the receiving transducer is the vector sum of the unscattered and scattered fields. In weak scattering the unscattered field is dominant and the resultant field can be treated as the unscattered field plus a perturbation. The net effect is primarily a distorted phasefront, while the amplitude or modulus of the wavefront remains reasonably intact. Refraction and strong scattering effect the wavefront more severely and are less responsive to these algorithms.

  11. Unexpected bismuth concentration profiles in metal-organic vapor phase epitaxy-grown Ga(As{sub 1−x}Bi{sub x})/GaAs superlattices revealed by Z-contrast scanning transmission electron microscopy imaging

    SciTech Connect

    Wood, A. W.; Babcock, S. E.; Guan, Y.; Forghani, K.; Anand, A.; Kuech, T. F.

    2015-03-01

    A set of GaAs{sub 1−x}Bi{sub x}/GaAs multilayer quantum-well structures was deposited by metal-organic vapor phase epitaxy at 390 °C and 420 °C. The precursor fluxes were introduced with the intent of growing discrete and compositionally uniform GaAs{sub 1−x}Bi{sub x} well and GaAs barrier layers in the epitaxial films. High-resolution high-angle annular-dark-field (or “Z-contrast”) scanning transmission electron microscopy imaging revealed concentration profiles that were periodic in the growth direction, but far more complicated in shape than the intended square wave. The observed composition profiles could explain various reports of physical properties measurements that suggest compositional inhomogeneity in GaAs{sub 1−x}Bi{sub x} alloys as they currently are grown.

  12. Atomic-scale observation of migration and coalescence of Au nanoclusters on YSZ surface by aberration-corrected STEM.

    PubMed

    Li, Junjie; Wang, Zhongchang; Chen, Chunlin; Huang, Sumei

    2014-07-01

    Unraveling structural dynamics of noble metal nanoclusters on oxide supports is critical to understanding reaction process and origin of catalytic activity in heterogeneous catalysts. Here, we show that aberration-corrected scanning transmission electron microscopy can provide direct atomic-resolution imaging of surface migration, coalescence, and atomic rearrangement of Au clusters on an Y:ZrO₂ (YSZ) support. The high resolution enables us to reveal migration and coalescence process of Au clusters at the atomic scale, and to demonstrate that the coalesced clusters undergo a cooperative atomic rearrangement, which transforms the coherent into incoherent Au/YSZ interface. This approach can help to elucidate atomistic mechanism of catalytic activities and to develop novel catalysts with enhanced functionality.

  13. Temporal integration property of stereopsis after higher-order aberration correction

    PubMed Central

    Kang, Jian; Dai, Yun; Zhang, Yudong

    2015-01-01

    Based on a binocular adaptive optics visual simulator, we investigated the effect of higher-order aberration correction on the temporal integration property of stereopsis. Stereo threshold for line stimuli, viewed in 550nm monochromatic light, was measured as a function of exposure duration, with higher-order aberrations uncorrected, binocularly corrected or monocularly corrected. Under all optical conditions, stereo threshold decreased with increasing exposure duration until a steady-state threshold was reached. The critical duration was determined by a quadratic summation model and the high goodness of fit suggested this model was reasonable. For normal subjects, the slope for stereo threshold versus exposure duration was about −0.5 on logarithmic coordinates, and the critical duration was about 200 ms. Both the slope and the critical duration were independent of the optical condition of the eye, showing no significant effect of higher-order aberration correction on the temporal integration property of stereopsis. PMID:26601010

  14. Dynamic Aberration Correction for Conformal Window of High-Speed Aircraft Using Optimized Model-Based Wavefront Sensorless Adaptive Optics.

    PubMed

    Dong, Bing; Li, Yan; Han, Xin-Li; Hu, Bin

    2016-09-02

    For high-speed aircraft, a conformal window is used to optimize the aerodynamic performance. However, the local shape of the conformal window leads to large amounts of dynamic aberrations varying with look angle. In this paper, deformable mirror (DM) and model-based wavefront sensorless adaptive optics (WSLAO) are used for dynamic aberration correction of an infrared remote sensor equipped with a conformal window and scanning mirror. In model-based WSLAO, aberration is captured using Lukosz mode, and we use the low spatial frequency content of the image spectral density as the metric function. Simulations show that aberrations induced by the conformal window are dominated by some low-order Lukosz modes. To optimize the dynamic correction, we can only correct dominant Lukosz modes and the image size can be minimized to reduce the time required to compute the metric function. In our experiment, a 37-channel DM is used to mimic the dynamic aberration of conformal window with scanning rate of 10 degrees per second. A 52-channel DM is used for correction. For a 128 × 128 image, the mean value of image sharpness during dynamic correction is 1.436 × 10(-5) in optimized correction and is 1.427 × 10(-5) in un-optimized correction. We also demonstrated that model-based WSLAO can achieve convergence two times faster than traditional stochastic parallel gradient descent (SPGD) method.

  15. Dynamic Aberration Correction for Conformal Window of High-Speed Aircraft Using Optimized Model-Based Wavefront Sensorless Adaptive Optics.

    PubMed

    Dong, Bing; Li, Yan; Han, Xin-Li; Hu, Bin

    2016-01-01

    For high-speed aircraft, a conformal window is used to optimize the aerodynamic performance. However, the local shape of the conformal window leads to large amounts of dynamic aberrations varying with look angle. In this paper, deformable mirror (DM) and model-based wavefront sensorless adaptive optics (WSLAO) are used for dynamic aberration correction of an infrared remote sensor equipped with a conformal window and scanning mirror. In model-based WSLAO, aberration is captured using Lukosz mode, and we use the low spatial frequency content of the image spectral density as the metric function. Simulations show that aberrations induced by the conformal window are dominated by some low-order Lukosz modes. To optimize the dynamic correction, we can only correct dominant Lukosz modes and the image size can be minimized to reduce the time required to compute the metric function. In our experiment, a 37-channel DM is used to mimic the dynamic aberration of conformal window with scanning rate of 10 degrees per second. A 52-channel DM is used for correction. For a 128 × 128 image, the mean value of image sharpness during dynamic correction is 1.436 × 10(-5) in optimized correction and is 1.427 × 10(-5) in un-optimized correction. We also demonstrated that model-based WSLAO can achieve convergence two times faster than traditional stochastic parallel gradient descent (SPGD) method. PMID:27598161

  16. Dynamic Aberration Correction for Conformal Window of High-Speed Aircraft Using Optimized Model-Based Wavefront Sensorless Adaptive Optics

    PubMed Central

    Dong, Bing; Li, Yan; Han, Xin-li; Hu, Bin

    2016-01-01

    For high-speed aircraft, a conformal window is used to optimize the aerodynamic performance. However, the local shape of the conformal window leads to large amounts of dynamic aberrations varying with look angle. In this paper, deformable mirror (DM) and model-based wavefront sensorless adaptive optics (WSLAO) are used for dynamic aberration correction of an infrared remote sensor equipped with a conformal window and scanning mirror. In model-based WSLAO, aberration is captured using Lukosz mode, and we use the low spatial frequency content of the image spectral density as the metric function. Simulations show that aberrations induced by the conformal window are dominated by some low-order Lukosz modes. To optimize the dynamic correction, we can only correct dominant Lukosz modes and the image size can be minimized to reduce the time required to compute the metric function. In our experiment, a 37-channel DM is used to mimic the dynamic aberration of conformal window with scanning rate of 10 degrees per second. A 52-channel DM is used for correction. For a 128 × 128 image, the mean value of image sharpness during dynamic correction is 1.436 × 10−5 in optimized correction and is 1.427 × 10−5 in un-optimized correction. We also demonstrated that model-based WSLAO can achieve convergence two times faster than traditional stochastic parallel gradient descent (SPGD) method. PMID:27598161

  17. Brief history of the Cambridge STEM aberration correction project and its progeny.

    PubMed

    Brown, L Michael; Batson, Philip E; Dellby, Niklas; Krivanek, Ondrej L

    2015-10-01

    We provide a brief history of the project to correct the spherical aberration of the scanning transmission electron microscope (STEM) that started in Cambridge (UK) and continued in Kirkland (WA, USA), Yorktown Heights (NY, USA), and other places. We describe the project in the full context of other aberration correction research and related work, partly in response to the incomplete context presented in the paper "In quest of perfection in electron optics: A biographical sketch of Harald Rose on the occasion of his 80th birthday", recently published in Ultramicroscopy.

  18. Brief history of the Cambridge STEM aberration correction project and its progeny.

    PubMed

    Brown, L Michael; Batson, Philip E; Dellby, Niklas; Krivanek, Ondrej L

    2015-10-01

    We provide a brief history of the project to correct the spherical aberration of the scanning transmission electron microscope (STEM) that started in Cambridge (UK) and continued in Kirkland (WA, USA), Yorktown Heights (NY, USA), and other places. We describe the project in the full context of other aberration correction research and related work, partly in response to the incomplete context presented in the paper "In quest of perfection in electron optics: A biographical sketch of Harald Rose on the occasion of his 80th birthday", recently published in Ultramicroscopy. PMID:26094204

  19. Exploring the depth range for three-dimensional laser machining with aberration correction.

    PubMed

    Salter, P S; Baum, M; Alexeev, I; Schmidt, M; Booth, M J

    2014-07-28

    The spherical aberration generated when focusing from air into another medium limits the depth at which ultrafast laser machining can be accurately maintained. We investigate how the depth range may be extended using aberration correction via a liquid crystal spatial light modulator (SLM), in both single point and parallel multi-point fabrication in fused silica. At a moderate numerical aperture (NA = 0.5), high fidelity fabrication with a significant level of parallelisation is demonstrated at the working distance of the objective lens, corresponding to a depth in the glass of 2.4 mm. With a higher numerical aperture (NA = 0.75) objective lens, single point fabrication is demonstrated to a depth of 1 mm utilising the full NA, and deeper with reduced NA, while maintaining high repeatability. We present a complementary theoretical model that enables prediction of the effectiveness of SLM based correction for different aberration magnitudes.

  20. An aberration corrected photoemission electron microscope at the advanced light source

    SciTech Connect

    Feng, J.; MacDowell, A.A.; Duarte, R.; Doran, A.; Forest, E.; Kelez, N.; Marcus, M.; Munson, D.; Padmore, H.; Petermann, K.; Raoux, S.; Robin, D.; Scholl, A.; Schlueter, R.; Schmid, P.; Stohr, J.; Wan, W.; Wei, D.H.; Wu, Y.

    2003-11-01

    Design of a new aberration corrected Photoemission electron microscope PEEM3 at the Advanced Light Source is outlined. PEEM3 will be installed on an elliptically polarized undulator beamline and will be used for the study of complex materials at high spatial and spectral resolution. The critical components of PEEM3 are the electron mirror aberration corrector and aberration-free magnetic beam separator. The models to calculate the optical properties of the electron mirror are discussed. The goal of the PEEM3 project is to achieve the highest possible transmission of the system at resolutions comparable to our present PEEM2 system (50 nm) and to enable significantly higher resolution, albeit at the sacrifice of intensity. We have left open the possibility to add an energy filter at a later date, if it becomes necessary driven by scientific need to improve the resolution further.

  1. Identification of light elements in silicon nitride by aberration-corrected scanning transmission electron microscopy.

    PubMed

    Idrobo, Juan C; Walkosz, Weronika; Klie, Robert F; Oğüt, Serdar

    2012-12-01

    In silicon nitride structural ceramics, the overall mechanical and thermal properties are controlled by the atomic and electronic structures at the interface between the ceramic grains and the amorphous intergranular films (IGFs) formed by various sintering additives. In the last ten years the atomic arrangements of heavy elements (rare-earths) at the Si(3)N(4)/IGF interfaces have been resolved. However, the atomic position of light elements, without which it is not possible to obtain a complete description of the interfaces, has been lacking. This review article details the authors' efforts to identify the atomic arrangement of light elements such as nitrogen and oxygen at the Si(3)N(4)/SiO(2) interface and in bulk Si(3)N(4) using aberration-corrected scanning transmission electron microscopy.

  2. Chromatic-aberration-corrected diffractive lenses for ultra-broadband focusing

    DOE PAGES

    Wang, Peng; Mohammad, Nabil; Menon, Rajesh

    2016-02-12

    We exploit the inherent dispersion in diffractive optics to demonstrate planar chromatic-aberration-corrected lenses. Specifically, we designed, fabricated and characterized cylindrical diffractive lenses that efficiently focus the entire visible band (450 nm to 700 nm) onto a single line. These devices are essentially pixelated, multi-level microstructures. Experiments confirm an average optical efficiency of 25% for a three-wavelength apochromatic lens whose chromatic focus shift is only 1.3 μm and 25 μm in the lateral and axial directions, respectively. Super-achromatic performance over the continuous visible band is also demonstrated with averaged lateral and axial focus shifts of only 1.65 μm and 73.6 μm,more » respectively. These lenses are easy to fabricate using single-step grayscale lithography and can be inexpensively replicated. Furthermore, these devices are thin (<3 μm), error tolerant, has low aspect ratio (<1:1) and offer polarization-insensitive focusing, all significant advantages compared to alternatives that rely on metasurfaces. Lastly, our design methodology offers high design flexibility in numerical aperture and focal length, and is readily extended to 2D.« less

  3. Chromatic-aberration-corrected diffractive lenses for ultra-broadband focusing

    PubMed Central

    Wang, Peng; Mohammad, Nabil; Menon, Rajesh

    2016-01-01

    We exploit the inherent dispersion in diffractive optics to demonstrate planar chromatic-aberration-corrected lenses. Specifically, we designed, fabricated and characterized cylindrical diffractive lenses that efficiently focus the entire visible band (450 nm to 700 nm) onto a single line. These devices are essentially pixelated, multi-level microstructures. Experiments confirm an average optical efficiency of 25% for a three-wavelength apochromatic lens whose chromatic focus shift is only 1.3 μm and 25 μm in the lateral and axial directions, respectively. Super-achromatic performance over the continuous visible band is also demonstrated with averaged lateral and axial focus shifts of only 1.65 μm and 73.6 μm, respectively. These lenses are easy to fabricate using single-step grayscale lithography and can be inexpensively replicated. Furthermore, these devices are thin (<3 μm), error tolerant, has low aspect ratio (<1:1) and offer polarization-insensitive focusing, all significant advantages compared to alternatives that rely on metasurfaces. Our design methodology offers high design flexibility in numerical aperture and focal length, and is readily extended to 2D. PMID:26868264

  4. Practical spatial resolution of electron energy loss spectroscopy in aberration corrected scanning transmission electron microscopy.

    PubMed

    Shah, A B; Ramasse, Q M; Wen, J G; Bhattacharya, A; Zuo, J M

    2011-08-01

    The resolution of electron energy loss spectroscopy (EELS) is limited by delocalization of inelastic electron scattering rather than probe size in an aberration corrected scanning transmission electron microscope (STEM). In this study, we present an experimental quantification of EELS spatial resolution using chemically modulated 2×(LaMnO(3))/2×(SrTiO(3)) and 2×(SrVO(3))/2×(SrTiO(3)) superlattices by measuring the full width at half maxima (FWHM) of integrated Ti M(2,3), Ti L(2,3), V L(2,3), Mn L(2,3), La N(4,5), La N(2,3) La M(4,5) and Sr L(3) edges over the superlattices. The EELS signals recorded using large collection angles are peaked at atomic columns. The FWHM of the EELS profile, obtained by curve-fitting, reveals a systematic trend with the energy loss for the Ti, V, and Mn edges. However, the experimental FWHM of the Sr and La edges deviates significantly from the observed experimental tendency.

  5. Picometre-precision analysis of scanning transmission electron microscopy images of platinum nanocatalysts.

    PubMed

    Yankovich, Andrew B; Berkels, Benjamin; Dahmen, W; Binev, P; Sanchez, S I; Bradley, S A; Li, Ao; Szlufarska, Izabela; Voyles, Paul M

    2014-06-11

    Measuring picometre-scale shifts in the positions of individual atoms in materials provides new insight into the structure of surfaces, defects and interfaces that influence a broad variety of materials' behaviour. Here we demonstrate sub-picometre precision measurements of atom positions in aberration-corrected Z-contrast scanning transmission electron microscopy images based on the non-rigid registration and averaging of an image series. Non-rigid registration achieves five to seven times better precision than previous methods. Non-rigidly registered images of a silica-supported platinum nanocatalyst show pm-scale contraction of atoms at a (111)/(111) corner towards the particle centre and expansion of a flat (111) facet. Sub-picometre precision and standardless atom counting with <1 atom uncertainty in the same scanning transmission electron microscopy image provide new insight into the three-dimensional atomic structure of catalyst nanoparticle surfaces, which contain the active sites controlling catalytic reactions.

  6. Canopy induced aberration correction in airborne electro-optical imaging systems

    NASA Astrophysics Data System (ADS)

    Harder, James A.; Sprague, Michaelene W.

    2011-11-01

    An increasing number of electro-optical systems are being used by pilots in tactical aircraft. This means that the afore mentioned systems must operate through the aircrafts canopy, unfortunately the canopy functions as a less than ideal lens element in the electro-optical sensor optical path. The canopy serves first and foremost as an aircraft structural component, considerations like minimizing the drag co-efficient and the ability to survive bird strikes take precedence over achieving optimal optical characteristics. This paper describes how the authors characterized the optical characteristics of an aircraft canopy. Families of modulation transfer functions were generated, for various viewing geometries through the canopy and for various electro-optical system entrance pupil diameters. These functions provided us with the means to significantly reduce the effect of the canopy "lens" on the performance of a representative electro-optical system, using an Astigmatic Corrector Lens. A comparison of the electro-optical system performance with and without correction is also presented.

  7. Imaging nanometre-scale structure in cells using in situ aberration correction.

    PubMed

    Fuller, C J; Straight, A F

    2012-10-01

    Accurate distance measurements of cellular structures on a length scale relevant to single macromolecules or macromolecular complexes present a major challenge for biological microscopy. In addition to the inherent challenges of overcoming the limits imposed by the diffraction of light, cells themselves are a complex and poorly understood optical environment. We present an extension of the high-resolution colocalization method to measure three dimensional distances between diffraction-limited objects using standard widefield fluorescence microscopy. We use this method to demonstrate that in three dimensions, cells intrinsically introduce a large and variable amount of chromatic aberration into optical measurements. We present a means of correcting this aberration in situ [termed 'Colocalization and In-situ Correction of Aberration for Distance Analysis' (CICADA)] by exploiting the fact that there is a linear relationship between the degree of aberration between different wavelengths. By labelling a cellular structure with redundantly multi-colour labelled antibodies, we can create an intracellular fiducial marker for correcting the individual aberrations between two different wavelengths in the same cells. Our observations demonstrate that with suitable corrections, nanometre scale three-dimensional distance measurements can be used to probe the substructure of macromolecular complexes within cells.

  8. High order aberration and straylight evaluation after cataract surgery with implantation of an aspheric, aberration correcting monofocal intraocular lens

    PubMed Central

    Kretz, Florian T A; Tandogan, Tamer; Khoramnia, Ramin; Auffarth, Gerd U

    2015-01-01

    AIM To evaluate the quality of vision in respect to high order aberrations and straylight perception after implantation of an aspheric, aberration correcting, monofocal intraocular lens (IOL). METHODS Twenty-one patients (34 eyes) aged 50 to 83y underwent cataract surgery with implantation of an aspheric, aberration correcting IOL (Tecnis ZCB00, Abbott Medical Optics). Three months after surgery they were examined for uncorrected (UDVA) and corrected distance visual acuity (CDVA), contrast sensitivity (CS) under photopic and mesopic conditions with and without glare source, ocular high order aberrations (HOA, Zywave II) and retinal straylight (C-Quant). RESULTS Postoperatively, patients achieved a postoperative CDVA of 0.0 logMAR or better in 97.1% of eyes. Mean values of high order abberations were +0.02±0.27 (primary coma components) and -0.04±0.16 (spherical aberration term). Straylight values of the C-Quant were 1.35±0.44 log which is within normal range of age matched phakic patients. The CS measurements under mesopic and photopic conditions in combination with and without glare did not show any statistical significance in the patient group observed (P≥0.28). CONCLUSION The implantation of an aspherical aberration correcting monofocal IOL after cataract surgery resulted in very low residual higher order aberration (HOA) and normal straylight. PMID:26309872

  9. In-situ Study of Dynamic Phenomena at Metal Nanosolder Interfaces Using Aberration Corrected Scanning Transmission Electron Microcopy.

    SciTech Connect

    Lu, Ping

    2014-10-01

    Controlling metallic nanoparticle (NP) interactions plays a vital role in the development of new joining techniques (nanosolder) that bond at lower processing temperatures but remain viable at higher temperatures. The pr imary objective of this project is t o develop a fundamental understanding of the actual reaction processes, associated atomic mechanisms, and the resulting microstructure that occur during thermally - driven bond formation concerning metal - metal nano - scale (%3C50nm) interfaces. In this LDRD pr oject, we have studied metallic NPs interaction at the elevated temperatures by combining in - situ transmission electron microscopy (TEM ) using an aberration - corrected scanning transmission electron microscope (AC - STEM) and atomic - scale modeling such as m olecular dynamic (MD) simulations. Various metallic NPs such as Ag, Cu and Au are synthesized by chemical routines. Numerous in - situ e xperiments were carried out with focus of the research on study of Ag - Cu system. For the first time, using in - situ STEM he ating experiments , we directly observed t he formation of a 3 - dimensional (3 - D) epitaxial Cu - Ag core - shell nanoparticle during the thermal interaction of Cu and Ag NPs at elevated temperatures (150 - 300 o C). The reaction takes place at temperatures as low as 150 o C and was only observed when care was taken to circumvent the effects of electron beam irradiation during STEM imaging. Atomic - scale modeling verified that the Cu - Ag core - shell structure is energetically favored, and indicated that this phenomenon is a nano - scale effect related to the large surface - to - volume ratio of the NPs. The observation potentially can be used for developing new nanosolder technology that uses Ag shell as the "glue" that stic ks the particles of Cu together. The LDRD has led to several journal publications and numerous conference presentations, and a TA. In addition, we have developed new TEM characterization techniques and phase

  10. Energy-based adaptive focusing of waves: application to noninvasive aberration correction of ultrasonic wavefields

    PubMed Central

    Herbert, Eric; Pernot, Mathieu; Montaldo, Gabriel; Fink, Mathias; Tanter, Mickael

    2009-01-01

    An aberration correction method based on the maximization of the wave intensity at the focus of an emitting array is presented. The potential of this new adaptive focusing technique is investigated for ultrasonic focusing in biological tissues. The acoustic intensity is maximized non invasively through the direct measurement or indirect estimation of the beam energy at the focus for a series of spatially coded emissions. For ultrasonic waves, the acoustic energy at the desired focus can be indirectly estimated from the local displacements induced in tissues by the ultrasonic radiation force of the beam. Based on the measurement of these displacements, this method allows the precise estimation of the phase and amplitude aberrations and consequently the correction of aberrations along the beam travel path. The proof of concept is first performed experimentally using a large therapeutic array with strong electronic phase aberrations (up to 2π). Displacements induced by the ultrasonic radiation force at the desired focus are indirectly estimated using the time shift of backscattered echoes recorded on the array. The phase estimation is deduced accurately using a direct inversion algorithm which reduces the standard deviation of the phase distribution from σ = 1.89 before correction to σ = 0.53 following correction. The corrected beam focusing quality is verified using a needle hydrophone. The peak intensity obtained through the aberrator is found to be −7.69 dB below the reference intensity obtained without any aberration. Using the phase correction, a sharp focus is restored through the aberrator with a relative peak intensity of −0.89 dB. The technique is tested experimentally using a linear transmit/receive array through a real aberrating layer. The array is used to automatically correct its beam quality, as it both generates the radiation force with coded excitations and indirectly estimates the acoustic intensity at the focus with speckle tracking. This

  11. Aberration corrected environmental STEM (AC ESTEM) for dynamic in-situ gas reaction studies of nanoparticle catalysts

    NASA Astrophysics Data System (ADS)

    Boyes, E. D.; Gai, P. L.

    2014-06-01

    Environmental scanning transmission electron microscopy (ESTEM) with aberration correction (AC) has recently been added to the capabilities of the more established ETEM for analysis of heterogeneous nanoparticle based catalysts. It has helped to reveal the importance and potentially unique properties of individual atoms as active sites in their own right as well as pathways between established nanoparticles. A new capability is introduced for dynamic in-situ experiments under controlled conditions of specimen temperature and gas environment related to real world conditions pertinent to a range of industrial and societal priorities for new and improved chemical processes, materials, fuels, pharmaceutical products and processes, and in control or remediation of environmental emissions.

  12. Evaluation of stacking faults and associated partial dislocations in AlSb/GaAs (001) interface by aberration-corrected high-resolution transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Wen, C.; Ge, B. H.; Cui, Y. X.; Li, F. H.; Zhu, J.; Yu, R.; Cheng, Z. Y.

    2014-11-01

    The stacking faults (SFs) in an AlSb/GaAs (001) interface were investigated using a 300 kV spherical aberration-corrected high-resolution transmission electron microscope (HRTEM). The structure and strain distribution of the single and intersecting (V-shaped) SFs associated with partial dislocations (PDs) were characterized by the [110] HRTEM images and geometric phase analysis, respectively. In the biaxial strain maps ɛxx and ɛyy, a SF can be divided into several sections under different strain states (positive or negative strain values). Furthermore, the strain state for the same section of a SF is in contrast to each other in ɛxx and ɛyy strain maps. The modification in the strain states was attributed to the variation in the local atomic displacements for the SF in the AlSb film on the GaAs substrate recorded in the lattice image. Finally, the single SF was found to be bounded by two 30° PDs. A pair of 30° PDs near the heteroepitaxial interface reacted to form a Lomer-Cottrell sessile dislocation located at the vertices of V-shaped SFs with opposite screw components. The roles of misfit dislocations, such as the PDs, in strain relaxation were also discussed.

  13. Evaluation of stacking faults and associated partial dislocations in AlSb/GaAs (001) interface by aberration-corrected high-resolution transmission electron microscopy

    SciTech Connect

    Wen, C.; Ge, B. H.; Cui, Y. X.; Li, F. H.; Zhu, J.; Yu, R.; Cheng, Z. Y.

    2014-11-15

    The stacking faults (SFs) in an AlSb/GaAs (001) interface were investigated using a 300 kV spherical aberration-corrected high-resolution transmission electron microscope (HRTEM). The structure and strain distribution of the single and intersecting (V-shaped) SFs associated with partial dislocations (PDs) were characterized by the [110] HRTEM images and geometric phase analysis, respectively. In the biaxial strain maps ε{sub xx} and ε{sub yy}, a SF can be divided into several sections under different strain states (positive or negative strain values). Furthermore, the strain state for the same section of a SF is in contrast to each other in ε{sub xx} and ε{sub yy} strain maps. The modification in the strain states was attributed to the variation in the local atomic displacements for the SF in the AlSb film on the GaAs substrate recorded in the lattice image. Finally, the single SF was found to be bounded by two 30° PDs. A pair of 30° PDs near the heteroepitaxial interface reacted to form a Lomer-Cottrell sessile dislocation located at the vertices of V-shaped SFs with opposite screw components. The roles of misfit dislocations, such as the PDs, in strain relaxation were also discussed.

  14. Fine structural features of nanoscale zero-valent iron characterized by spherical aberration corrected scanning transmission electron microscopy (Cs-STEM).

    PubMed

    Liu, Airong; Zhang, Wei-xian

    2014-09-21

    An angstrom-resolution physical model of nanoscale zero-valent iron (nZVI) is generated with a combination of spherical aberration corrected scanning transmission electron microscopy (Cs-STEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS) on the Fe L-edge. Bright-field (BF), high-angle annular dark-field (HAADF) and secondary electron (SE) imaging of nZVI acquired by a Hitachi HD-2700 STEM show near atomic resolution images and detailed morphological and structural information of nZVI. The STEM-EDS technique confirms that the fresh nZVI comprises of a metallic iron core encapsulated with a thin layer of iron oxides or oxyhydroxides. SAED patterns of the Fe core suggest the polycrystalline structure in the metallic core and amorphous nature of the oxide layer. Furthermore, Fe L-edge of EELS shows varied structural features from the innermost Fe core to the outer oxide shell. A qualitative analysis of the Fe L(2,3) edge fine structures reveals that the shell of nZVI consists of a mixed Fe(II)/Fe(III) phase close to the Fe (0) interface and a predominantly Fe(III) at the outer surface of nZVI.

  15. Interaction between single gold atom and the graphene edge: A study via aberration-corrected transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Hongtao; Li, Kun; Cheng, Yingchun; Wang, Qingxiao; Yao, Yingbang; Schwingenschlögl, Udo; Zhang, Xixiang; Yang, Wei

    2012-04-01

    Interaction between single noble metal atoms and graphene edges has been investigated via aberration-corrected and monochromated transmission electron microscopy. A collective motion of the Au atom and the nearby carbon atoms is observed in transition between energy-favorable configurations. Most trapping and detrapping processes are assisted by the dangling carbon atoms, which are more susceptible to knock-on displacements by electron irradiation. Thermal energy is lower than the activation barriers in transition among different energy-favorable configurations, which suggests electron-beam irradiation can be an efficient way of engineering the graphene edge with metal atoms.Interaction between single noble metal atoms and graphene edges has been investigated via aberration-corrected and monochromated transmission electron microscopy. A collective motion of the Au atom and the nearby carbon atoms is observed in transition between energy-favorable configurations. Most trapping and detrapping processes are assisted by the dangling carbon atoms, which are more susceptible to knock-on displacements by electron irradiation. Thermal energy is lower than the activation barriers in transition among different energy-favorable configurations, which suggests electron-beam irradiation can be an efficient way of engineering the graphene edge with metal atoms. Electronic supplementary information (ESI) available: Additional Figures for characterization of mono-layer CVD graphene samples with free edges and Pt atoms decorations and analysis of the effect of electron irradiation; supporting movie on edge evolution. See DOI: 10.1039/c2nr00059h

  16. Computed Ultrasound Tomography in Echo mode (CUTE) of speed of sound for diagnosis and for aberration correction in pulse-echo sonography

    NASA Astrophysics Data System (ADS)

    Jaeger, Michael; Held, Gerrit; Preisser, Stefan; Peeters, Sara; Grünig, Michael; Frenz, Martin

    2014-03-01

    Sound speed as a diagnostic marker for various diseases of human tissue has been of interest for a while. Up to now, mostly transmission ultrasound computed tomography (UCT) was able to detect spatially resolved sound speed, and its promise as a diagnostic tool has been demonstrated. However, UCT is limited to acoustically transparent samples such as the breast. We present a novel technique where spatially resolved detection of sound speed can be achieved using conventional pulse-echo equipment in reflection mode. For this purpose, pulse-echo images are acquired under various transmit beam directions and a two-dimensional map of the sound speed is reconstructed from the changing phase of local echoes using a direct reconstruction method. Phantom results demonstrate that a high spatial resolution (1 mm) and contrast (0.5 % of average sound speed) can be achieved suitable for diagnostic purposes. In comparison to previous reflection-mode based methods, CUTE works also in a situation with only diffuse echoes, and its direct reconstruction algorithm enables real-time application. This makes it suitable as an addition to conventional clinical ultrasound where it has the potential to benefit diagnosis in a multimodal approach. In addition, knowledge of the spatial distribution of sound speed allows full aberration correction and thus improved spatial resolution and contrast of conventional B-mode ultrasound.

  17. Quantitative analysis of interfacial strain in InAs/GaSb superlattices by aberration-corrected HRTEM and HAADF-STEM.

    PubMed

    Mahalingam, Krishnamurthy; Haugan, Heather J; Brown, Gail J; Eyink, Kurt G

    2013-04-01

    The strain distribution across interfaces in InAs/GaSb superlattices grown on (100)-GaSb substrates is investigated by aberration corrected transmission electron microscopy. Atomic resolution images of interfaces were obtained by conventional high resolution transmission electron microscopy (HRTEM), using the negative spherical-aberration imaging mode, and by scanning transmission electron microscopy (STEM), using the high-angle annular dark-field (HAADF) imaging mode. The local atomic displacements across interfaces were determined from these images using the peak pair algorithm, from which strain maps were calculated with respect to a reference lattice extracted from the GaSb substrate region. Both techniques yield consistent results, which reveal that the InAs-on-GaSb interface is nearly strain balanced, whereas the GaSb-on-InAs interface is in tensile strain, indicating that the prevalent bond type at this interface is Ga-As. In addition, the GaSb layers in the superlattice are compressively strained indicating the incorporation of In into these layers. Further analysis of the HAADF-STEM images indicates an estimated 4% In content in the GaSb layers and that the GaSb-on-InAs interface contributes to about 27% of the overall superlattice strain. The strain measurements in the InAs layers are in good agreement with the theoretical values determined from elastic constants. Furthermore, the overall superlattice strain determined from this analysis is also in good agreement with the measurements determined by high-resolution X-ray diffraction.

  18. Non-common path aberration correction in an adaptive optics scanning ophthalmoscope.

    PubMed

    Sulai, Yusufu N; Dubra, Alfredo

    2014-09-01

    The correction of non-common path aberrations (NCPAs) between the imaging and wavefront sensing channel in a confocal scanning adaptive optics ophthalmoscope is demonstrated. NCPA correction is achieved by maximizing an image sharpness metric while the confocal detection aperture is temporarily removed, effectively minimizing the monochromatic aberrations in the illumination path of the imaging channel. Comparison of NCPA estimated using zonal and modal orthogonal wavefront corrector bases provided wavefronts that differ by ~λ/20 in root-mean-squared (~λ/30 standard deviation). Sequential insertion of a cylindrical lens in the illumination and light collection paths of the imaging channel was used to compare image resolution after changing the wavefront correction to maximize image sharpness and intensity metrics. Finally, the NCPA correction was incorporated into the closed-loop adaptive optics control by biasing the wavefront sensor signals without reducing its bandwidth.

  19. Non-common path aberration correction in an adaptive optics scanning ophthalmoscope

    PubMed Central

    Sulai, Yusufu N.; Dubra, Alfredo

    2014-01-01

    The correction of non-common path aberrations (NCPAs) between the imaging and wavefront sensing channel in a confocal scanning adaptive optics ophthalmoscope is demonstrated. NCPA correction is achieved by maximizing an image sharpness metric while the confocal detection aperture is temporarily removed, effectively minimizing the monochromatic aberrations in the illumination path of the imaging channel. Comparison of NCPA estimated using zonal and modal orthogonal wavefront corrector bases provided wavefronts that differ by ~λ/20 in root-mean-squared (~λ/30 standard deviation). Sequential insertion of a cylindrical lens in the illumination and light collection paths of the imaging channel was used to compare image resolution after changing the wavefront correction to maximize image sharpness and intensity metrics. Finally, the NCPA correction was incorporated into the closed-loop adaptive optics control by biasing the wavefront sensor signals without reducing its bandwidth. PMID:25401020

  20. Investigating a method for non-invasive ultrasound aberration correction through the skull bone

    NASA Astrophysics Data System (ADS)

    O'Reilly, Meaghan A.; Jones, Ryan M.; Hynynen, Kullervo

    2014-03-01

    Ultrasound imaging can be performed through narrow acoustic windows in the skull in order to minimize skull distortions. Alternatively, passive imaging using a larger aperture array can be used, which affords better resolution at the low frequencies that best penetrate the skull bone. However, to ensure image quality, it is necessary to correct for the distorting effects of the skull. In this study we examine a method to correct the distortions caused by a human skull using passive imaging of single microbubbles. The method is compared with images produced without phase correction, and those produced using a gold-standard invasive phase correction method. Using the non-invasive technique, the -6dB volume was found to vary by less than 22% from the invasive phase correction technique. By comparison, the -6dB volume when no correction was used was almost 300% larger than using the invasive correction technique. The bubblebased method introduced a positional error in the resulting image, which was most prevalent in the axial direction (on the order of 1 mm). The corrected image was biased by the location of the bubble used to calculate the correction terms. In the future, this method might be improved by using multiple bubbles to correct different regions of the image.

  1. In situ observation on hydrogenation of Mg-Ni films using environmental transmission electron microscope with aberration correction

    SciTech Connect

    Matsuda, Junko; Yoshida, Kenta; Sasaki, Yukichi; Uchiyama, Naoki; Akiba, Etsuo

    2014-08-25

    In situ transmission electron microscopy (TEM) was performed to observe the hydrogenation of Mg-Ni films in a hydrogen atmosphere of 80–100 Pa. An aberration-corrected environmental TEM with a differential pumping system allows us to reveal the Angstrom-scale structure of the films in the initial stage of hydrogenation: first, nucleation and growth of Mg{sub 2}NiH{sub 4} crystals with a lattice spacing of 0.22 nm in an Mg-rich amorphous matrix of the film occurs within 20 s after the start of the high-resolution observation, then crystallization of MgH{sub 2} with a smaller spacing of 0.15 nm happens after approximately 1 min. Our in situ TEM method is also applicable to the analysis of other hydrogen-related materials.

  2. The Stanford Nanocharacterization Laboratory (SNL) and Recent Applications of an Aberration-Corrected Environmental Transmission Electron Microscope**

    PubMed Central

    Sinclair, Robert; Kempen, Paul Joseph; Chin, Richard; Koh, Ai Leen

    2014-01-01

    This article describes the establishment, over a period of ten years or so, of a multi-user, institution-wide facility for the characterization of materials and devices at the nano-scale. Emphasis is placed on the type of equipment that we have found to be most useful for our users, and the business strategy that maintains its operations. A central component of our facility is an aberration-corrected environmental transmission electron microscope and its application is summarized in the studies of plasmon energies of silver nanoparticles, the band gap of PbS quantum dots, atomic site occupancy near grain boundaries in yttria stabilized zirconia, the lithiation of silicon nanoparticles, in situ observations on carbon nanotube oxidation and the electron tomography of varicella zoster virus nucleocapsids. PMID:25364299

  3. Aberration corrected 1.2-MV cold field-emission transmission electron microscope with a sub-50-pm resolution

    SciTech Connect

    Akashi, Tetsuya; Takahashi, Yoshio; Tanigaki, Toshiaki Shimakura, Tomokazu; Kawasaki, Takeshi; Furutsu, Tadao; Shinada, Hiroyuki; Osakabe, Nobuyuki; Müller, Heiko; Haider, Maximilian; Tonomura, Akira

    2015-02-16

    Atomic-resolution electromagnetic field observation is critical to the development of advanced materials and to the unveiling of their fundamental physics. For this purpose, a spherical-aberration corrected 1.2-MV cold field-emission transmission electron microscope has been developed. The microscope has the following superior properties: stabilized accelerating voltage, minimized electrical and mechanical fluctuation, and coherent electron emission. These properties have enabled to obtain 43-pm information transfer. On the bases of these performances, a 43-pm resolution has been obtained by correcting lens aberrations up to the third order. Observations of GaN [411] thin crystal showed a projected atomic locations with a separation of 44 pm.

  4. Controlled polarity of sputter-deposited aluminum nitride on metals observed by aberration corrected scanning transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Harumoto, T.; Sannomiya, T.; Matsukawa, Y.; Muraishi, S.; Shi, J.; Nakamura, Y.; Sawada, H.; Tanaka, T.; Tanishiro, Y.; Takayanagi, K.

    2013-02-01

    The polarity determination process of sputter-deposited aluminum nitride (AlN) on metals has been analyzed using aberration corrected atomic resolution scanning transmission electron microscope. Direct growth of c-axis orientated AlN on face centered cubic metals (fcc) (111) with the local epitaxy has been observed, and the polarity was determined at the AlN/metal interface. We found that the AlN polarity can be controlled by the base metal layer: N-polarity AlN grows on Pt(111) while Al-polarity AlN forms on Al(111). Based on these results, the growth mechanism of AlN on metals is discussed.

  5. Controlled polarity of sputter-deposited aluminum nitride on metals observed by aberration corrected scanning transmission electron microscopy

    SciTech Connect

    Harumoto, T.; Sannomiya, T.; Matsukawa, Y.; Muraishi, S.; Shi, J.; Nakamura, Y.; Sawada, H.; Tanaka, T.; Tanishiro, Y.; Takayanagi, K.

    2013-02-28

    The polarity determination process of sputter-deposited aluminum nitride (AlN) on metals has been analyzed using aberration corrected atomic resolution scanning transmission electron microscope. Direct growth of c-axis orientated AlN on face centered cubic metals (fcc) (111) with the local epitaxy has been observed, and the polarity was determined at the AlN/metal interface. We found that the AlN polarity can be controlled by the base metal layer: N-polarity AlN grows on Pt(111) while Al-polarity AlN forms on Al(111). Based on these results, the growth mechanism of AlN on metals is discussed.

  6. Progress on PEEM3 - An Aberration Corrected X-Ray PhotoemissionElectron Microscope at the ALS

    SciTech Connect

    MacDowell, Alastair A.; Feng, J.; DeMello, A.; Doran, A.; Duarte,R.; Forest, E.; Kelez, N.; Marcus, M.A.; Miller, T.; Padmore, H.A.; Raoux, S.; Robin, D.; Scholl, A.; Schlueter, R.; Schmid, P.; Stohr, J.; Wan, W.; Wei, D.H.; Wu, Y.

    2006-05-20

    A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed and built at the Advanced Light Source (ALS). An electron mirror combined with a much-simplified magnetic dipole separator is to be used to provide simultaneous correction of spherical and chromatic aberrations. It is installed on an elliptically polarized undulator (EPU) beamline, and will be operated with very high spatial resolution and high flux to study the composition, structure, electric and magnetic properties of complex materials. The instrument has been designed and is described. The instrumental hardware is being deployed in 2 phases. The first phase is the deployment of a standard PEEM type microscope consisting of the standard linear array of electrostatic electron lenses. The second phase will be the installation of the aberration corrected upgrade to improve resolution and throughput. This paper describes progress as the instrument enters the commissioning part of the first phase.

  7. Characterization of surface metallic states in SrTiO3 by means of aberration corrected electron microscopy.

    PubMed

    Sánchez-Santolino, G; Tornos, J; Bruno, F Y; Cuellar, F A; Leon, C; Santamaría, J; Pennycook, S J; Varela, M

    2013-04-01

    An unusual conducting surface state can be produced in SrTiO3 substrates by irradiation with Argon ions from a plasma source, at low energy and high doses. The effects of irradiation are analyzed here by atomic force microscopy (AFM) and aberration corrected scanning transmission electron microscopy (STEM) combined with electron energy loss spectroscopy (EELS). Depth sensitive studies demonstrate the existence of a heavily damaged surface layer and an oxygen vacancy rich layer immediately underneath, both induced during the irradiation process. We find a clear dependence of the Ti oxidation state with the depth, with a very intense Ti(3+) component near the surface. Oxygen vacancies act as n-type doping by releasing electrons into the lattice and producing an insulator-to-metal transition, which explains the unusual metallic behavior of these samples.

  8. Design and Performance Characteristics of the ORNL AdvancedMicroscopy Laboratory and JEOL 2200FS-AC Aberration-CorrectedSTEM/TEM

    SciTech Connect

    Allard, Lawrence F.; Blom, Douglas A.; O'Keefe, Michael A.; Mishina, S.

    2005-02-15

    At ORNL, the new Advanced Microscopy Laboratory (AML) has recently been completed, with two aberration-corrected instruments installed, and two more planned in the near future to fill the 4-laboratory building. The installed JEOL 2200FS-AC has demonstrated aTEM information limit of 0.9A. This limit is expected given the measured instrument parameters (HT and OL power supply stabilities, beam energy spread, etc.), and illustrates that the environmental influences are not adversely affecting the instrument performance. In STEM high-angle annular dark-field (HA-ADF) mode, images of a thin Si crystal in<110>zone axis orientation, after primary aberrations in the illuminating beam were optimally corrected, showed a significant vibration effect. The microscope is fitted with three magnetically levitated turbo pumps (one on the column at about the specimen position,and two near floor level) that pump the Omega energy filter and detector chamber. These pumps run at 48,000 rpm, precisely equivalent to 800Hz. It was determined that the upper turbo pump was contributing essentially all of the 800Hz signal to the image, and in fact that the pump was defective. After replacing the pump with one significantly quieter than the original, the Si atomic column image and associated diffractogram(Fig. 4b) show a much-reduced effect of the 800Hz signal, but still some residual effect from the turbo pump. The upper pump will be removed from the main column to an adjacent frame on the floor, and will have a large-diameter, well-damped, pump line to the original connection to the column to effectively isolate the pump from the column. If the 800Hz signal results from mechanical vibrations, they will be damped, and if the signal results from acoustic coupling to the column, it can be damped by appropriate acoustic materials.

  9. Quantitative atom column position analysis at the incommensurate interfaces of a (PbS)(1.14)NbS(2) misfit layered compound with aberration-corrected HRTEM.

    PubMed

    Garbrecht, M; Spiecker, E; Tillmann, K; Jäger, W

    2011-02-01

    Aberration-corrected HRTEM is applied to explore the potential of NCSI contrast imaging to quantitatively analyse the complex atomic structure of misfit layered compounds and their incommensurate interfaces. Using the (PbS)(1.14)NbS(2) misfit layered compound as a model system it is shown that atom column position analyses at the incommensurate interfaces can be performed with precisions reaching a statistical accuracy of ±6pm. The procedure adopted for these studies compares experimental images taken from compound regions free of defects and interface modulations with a structure model derived from XRD experiments and with multi-slice image simulations for the corresponding NCSI contrast conditions used. The high precision achievable in such experiments is confirmed by a detailed quantitative analysis of the atom column positions at the incommensurate interfaces, proving a tetragonal distortion of the monochalcogenide sublattice.

  10. Phase-aberration correction using signals from point reflectors and diffuse scatterers: basic principles.

    PubMed

    Flax, S W; O'Donnell, M

    1988-01-01

    Methods for correction of phase aberrations induced by near-field variations in the index of refraction are explored. Using signals obtained from a sampled aperture (i.e. transducer array), phase aberrations can be accurately measured with a correlation approach similar to methods used in adaptive optics and radar. However, the method presented here has no need for a beacon or an ideal point reflector to act as a source for estimating phase errors. It uses signals from random collections of scatterers to determine phase aberrations accurately. Because there is no longer a need for a beacon signal, the method is directly applicable not only to medical ultrasound imaging but also to any coherent imaging system with a sampled aperture, such as radar and sonar.

  11. Anisotropic aberration correction using region of interest based digital adaptive optics in Fourier domain OCT.

    PubMed

    Kumar, Abhishek; Kamali, Tschackad; Platzer, René; Unterhuber, Angelika; Drexler, Wolfgang; Leitgeb, Rainer A

    2015-04-01

    In this paper a numerical technique is presented to compensate for anisotropic optical aberrations, which are usually present across the lateral field of view in the out of focus regions, in high resolution optical coherence tomography and microscopy (OCT/OCM) setups. The recorded enface image field at different depths in the tomogram is digitally divided into smaller sub-regions or the regions of interest (ROIs), processed individually using subaperture based digital adaptive optics (DAO), and finally stitched together to yield a final image with a uniform diffraction limited resolution across the entire field of view (FOV). Using this method, a sub-micron lateral resolution is achieved over a depth range of 218 [Formula: see text]for a nano-particle phantom sample imaged using a fiber based point scanning spectral domain (SD) OCM system with a limited depth of focus (DOF) of ~7 [Formula: see text]at a numerical aperture (NA) of 0.6. Thus, an increase in DOF by ~30x is demonstrated in this case. The application of this method is also shown in ex vivo mouse adipose tissue.

  12. Anisotropic aberration correction using region of interest based digital adaptive optics in Fourier domain OCT

    PubMed Central

    Kumar, Abhishek; Kamali, Tschackad; Platzer, René; Unterhuber, Angelika; Drexler, Wolfgang; Leitgeb, Rainer A.

    2015-01-01

    In this paper a numerical technique is presented to compensate for anisotropic optical aberrations, which are usually present across the lateral field of view in the out of focus regions, in high resolution optical coherence tomography and microscopy (OCT/OCM) setups. The recorded enface image field at different depths in the tomogram is digitally divided into smaller sub-regions or the regions of interest (ROIs), processed individually using subaperture based digital adaptive optics (DAO), and finally stitched together to yield a final image with a uniform diffraction limited resolution across the entire field of view (FOV). Using this method, a sub-micron lateral resolution is achieved over a depth range of 218 μmfor a nano-particle phantom sample imaged using a fiber based point scanning spectral domain (SD) OCM system with a limited depth of focus (DOF) of ~7 μmat a numerical aperture (NA) of 0.6. Thus, an increase in DOF by ~30x is demonstrated in this case. The application of this method is also shown in ex vivo mouse adipose tissue. PMID:25908999

  13. Design and progress toward a multi-conjugate adaptive optics system for distributed aberration correction

    SciTech Connect

    Baker, K; Olivier, S; Tucker, J; Silva, D; Gavel, D; Lim, R; Gratrix, E

    2004-08-17

    This article investigates the use of a multi-conjugate adaptive optics system to improve the field-of-view for the system. The emphasis of this research is to develop techniques to improve the performance of optical systems with applications to horizontal imaging. The design and wave optics simulations of the proposed system are given. Preliminary results from the multi-conjugate adaptive optics system are also presented. The experimental system utilizes a liquid-crystal spatial light modulator and an interferometric wave-front sensor for correction and sensing of the phase aberrations, respectively.

  14. High-resolution adaptive optics scanning laser ophthalmoscope with dual deformable mirrors for large aberration correction

    SciTech Connect

    Chen, D; Jones, S M; Silva, D A; Olivier, S S

    2007-01-25

    Scanning laser ophthalmoscopes with adaptive optics (AOSLO) have been shown previously to provide a noninvasive, cellular-scale view of the living human retina. However, the clinical utility of these systems has been limited by the available deformable mirror technology. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina, making the AOSLO system a viable, non-invasive, high-resolution imaging tool for clinical diagnostics. We used a bimorph deformable mirror to correct low-order aberrations with relatively large amplitudes. The bimorph mirror is manufactured by Aoptix, Inc. with 37 elements and 18 {micro}m stroke in a 10 mm aperture. We used a MEMS deformable mirror to correct high-order aberrations with lower amplitudes. The MEMS mirror is manufactured by Boston Micromachine, Inc with 144 elements and 1.5 {micro}m stroke in a 3 mm aperture. We have achieved near diffraction-limited retina images using the dual deformable mirrors to correct large aberrations up to {+-} 3D of defocus and {+-} 3D of cylindrical aberrations with test subjects. This increases the range of spectacle corrections by the AO systems by a factor of 10, which is crucial for use in the clinical environment. This ability for large phase compensation can eliminate accurate refractive error fitting for the patients, which greatly improves the system ease of use and efficiency in the clinical environment.

  15. Aberration-corrected scanning transmission electron microscopy for complex transition metal oxides

    NASA Astrophysics Data System (ADS)

    Qing-Hua, Zhang; Dong-Dong, Xiao; Lin, Gu

    2016-06-01

    Lattice, charge, orbital, and spin are the four fundamental degrees of freedom in condensed matter, of which the interactive coupling derives tremendous novel physical phenomena, such as high-temperature superconductivity (high-T c SC) and colossal magnetoresistance (CMR) in strongly correlated electronic system. Direct experimental observation of these freedoms is essential to understanding the structure-property relationship and the physics behind it, and also indispensable for designing new materials and devices. Scanning transmission electron microscopy (STEM) integrating multiple techniques of structure imaging and spectrum analysis, is a comprehensive platform for providing structural, chemical and electronic information of materials with a high spatial resolution. Benefiting from the development of aberration correctors, STEM has taken a big breakthrough towards sub-angstrom resolution in last decade and always steps forward to improve the capability of material characterization; many improvements have been achieved in recent years, thereby giving an in-depth insight into material research. Here, we present a brief review of the recent advances of STEM by some representative examples of perovskite transition metal oxides; atomic-scale mapping of ferroelectric polarization, octahedral distortions and rotations, valence state, coordination and spin ordering are presented. We expect that this brief introduction about the current capability of STEM could facilitate the understanding of the relationship between functional properties and these fundamental degrees of freedom in complex oxides. Project supported by the National Key Basic Research Project, China (Grant No. 2014CB921002), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB07030200), and the National Natural Science Foundation of China (Grant Nos. 51522212 and 51421002).

  16. Double-aberration corrected TEM/STEM of solid acid nanocatalysts in the development of pharmaceutical NSAIDS

    NASA Astrophysics Data System (ADS)

    Yoshida, K.; Shiju, N.; Brown, R.; Wright, I.; Boyes, E. D.; Gai, P. L.

    2012-07-01

    We report nanostructural and physico-chemical studies in the development of an efficient low temperature heterogeneous catalytic process for nonsteroidal anti-inflammatory drugs (NSAIDS) such as N-acetyl-p-aminophenol (paracetamol or acetaminophen) on tungstated zirconia nanocatalysts. Using a double-aberration corrected TEM/STEM, modified in-house for in-situ studies at the sub-Angstrom level, we directly observed in real-time, the dynamic precursor transformation to the active catalyst. We quantified the observations with catalytic activity studies for the NSAIDS. The studies have provided the direct evidence for single tungsten promoter atoms and surface WOx species of <= 0.35 nm, with nanoclusters of WOx (0.6 to 1nm), located at grain boundaries on the surface of the zirconia nanoparticles. The correlation between the nanostructure and catalytic activity indicates that the species create Brønsted acid sites highly active for the low temperature process. The results open up opportunities for developing green heterogeneous methods for pharmaceuticals.

  17. Spectroscopic imaging in electron microscopy

    SciTech Connect

    Pennycook, Stephen J; Colliex, C.

    2012-01-01

    In the scanning transmission electron microscope, multiple signals can be simultaneously collected, including the transmitted and scattered electron signals (bright field and annular dark field or Z-contrast images), along with spectroscopic signals such as inelastically scattered electrons and emitted photons. In the last few years, the successful development of aberration correctors for the electron microscope has transformed the field of electron microscopy, opening up new possibilities for correlating structure to functionality. Aberration correction not only allows for enhanced structural resolution with incident probes into the sub-angstrom range, but can also provide greater probe currents to facilitate mapping of intrinsically weak spectroscopic signals at the nanoscale or even the atomic level. In this issue of MRS Bulletin, we illustrate the power of the new generation of electron microscopes with a combination of imaging and spectroscopy. We show the mapping of elemental distributions at atomic resolution and also the mapping of electronic and optical properties at unprecedented spatial resolution, with applications ranging from graphene to plasmonic nanostructures, and oxide interfaces to biology.

  18. Three-dimensional locations of gold-labeled proteins in a whole mount eukaryotic cell obtained with 3 nm precision using aberration-corrected scanning transmission electron microscopy

    PubMed Central

    Dukes, Madeline J.; Ramachandra, Ranjan; Baudoin, Jean-Pierre; Jerome, W. Gray; de Jonge, Niels

    2011-01-01

    Three-dimensional (3D) maps of proteins within the context of whole cells are important for investigating cellular function. However, 3D reconstructions of whole cells are challenging to obtain using conventional transmission electron microscopy (TEM). We describe a methodology to determine the 3D locations of proteins labeled with gold nanoparticles on whole eukaryotic cells. The epidermal growth factor receptors on COS7 cells were labeled with gold nanoparticles, and critical-point dried whole-mount cell samples were prepared. 3D focal series were obtained with aberration-corrected scanning transmission electron microscopy (STEM), without tilting the specimen. The axial resolution was improved with deconvolution. The vertical locations of the nanoparticles in a whole-mount cell were determined with a precision of 3 nm. From the analysis of the variation of the axial positions of the labels we concluded that the cellular surface was ruffled. To achieve sufficient stability of the sample under the electron beam irradiation during the recording of the focal series, the sample was carbon coated. A quantitative method was developed to analyze the stability of the ultrastructure after electron beam irradiation using TEM. The results of this study demonstrate the feasibility of using aberration-corrected STEM to study the 3D nanoparticle distribution in whole cells. PMID:21440635

  19. Three-dimensional locations of gold-labeled proteins in a whole mount eukaryotic cell obtained with 3nm precision using aberration-corrected scanning transmission electron microscopy.

    PubMed

    Dukes, Madeline J; Ramachandra, Ranjan; Baudoin, Jean-Pierre; Gray Jerome, W; de Jonge, Niels

    2011-06-01

    Three-dimensional (3D) maps of proteins within the context of whole cells are important for investigating cellular function. However, 3D reconstructions of whole cells are challenging to obtain using conventional transmission electron microscopy (TEM). We describe a methodology to determine the 3D locations of proteins labeled with gold nanoparticles on whole eukaryotic cells. The epidermal growth factor receptors on COS7 cells were labeled with gold nanoparticles, and critical-point dried whole-mount cell samples were prepared. 3D focal series were obtained with aberration-corrected scanning transmission electron microscopy (STEM), without tilting the specimen. The axial resolution was improved with deconvolution. The vertical locations of the nanoparticles in a whole-mount cell were determined with a precision of 3nm. From the analysis of the variation of the axial positions of the labels we concluded that the cellular surface was ruffled. To achieve sufficient stability of the sample under electron beam irradiation during the recording of the focal series, the sample was carbon coated. A quantitative method was developed to analyze the stability of the ultrastructure after electron beam irradiation using TEM. The results of this study demonstrate the feasibility of using aberration-corrected STEM to study the 3D nanoparticle distribution in whole cells.

  20. An aberration-corrected STEM study of structural defects in epitaxial GaN thin films grown by ion beam assisted MBE.

    PubMed

    Poppitz, David; Lotnyk, Andriy; Gerlach, Jürgen W; Lenzner, Jörg; Grundmann, Marius; Rauschenbach, Bernd

    2015-06-01

    Ion-beam assisted molecular-beam epitaxy was used for direct growth of epitaxial GaN thin films on super-polished 6H-SiC(0001) substrates. The GaN films with different film thicknesses were studied using reflection high energy electron diffraction, X-ray diffraction, cathodoluminescence and primarily aberration-corrected scanning transmission electron microscopy techniques. Special attention was devoted to the microstructural characterization of GaN thin films and the GaN-SiC interface on the atomic scale. The results show a variety of defect types in the GaN thin films and at the GaN-SiC interface. A high crystalline quality of the produced hexagonal GaN thin films was demonstrated. The gained results are discussed.

  1. Array elevation requirements in phase aberration correction using an 8x128 1.75D array

    NASA Astrophysics Data System (ADS)

    Fernandez, Anna T.; Dahl, Jeremy J.; Dumont, Douglas M.; Trahey, Gregg E.

    2002-04-01

    Accurate measurement of tissue aberrations is necessary for effective adaptive ultrasound imaging. Higher order arrays provide more elements and a larger array footprint over which echo signals can be acquired. This allows for better sampling of the aberrator in both the azimuthal and elevation dimensions. These measured aberration profiles can then be used to correct the timing of transmitted and received RF signals to generate new images. We acquired single channel RF data on a 6.7 MHz, 8 x 128 array (Tetrad Co.) operating at F/1.0 in azimuth and F/2.9 in elevation. This array was interfaced to a Siemens Elegra scanner, allowing for data acquisition during routine phantom and clinical scanning. One-dimensional and two-dimensional physical near-field aberrators were used while imaging speckle only and spherical cyst-mimicking phantoms. In some experiments, neighboring elements were electronically tied in elevation to form ``taller'' elements. We collected individual channel data on each of 6 physical rows and then on a combination of rows to form 3x128, 2x128, and 1x128 arrays over a 6x128 aperture of the array. A least-mean-squares algorithm was employed to estimate the arrival time error induced by the tissue for the different array geometries. These aberration measurements were used to correct the images. In addition, point target simulations were performed to characterize the algorithm's performance for all four different array configurations. We present the performance of the adaptive imaging algorithm and discuss methods of combining arrival time profiles from axial and lateral tissue regions to improve adaptive imaging performance. Contrast results in simulation and phantom experiments with different aberrators are presented. We also discuss, in the context of our aberration measurement profiles, the array geometry requirements for successful adaptive imaging and the effects of the aberrators on sidelobe strength and contrast measurement. Results from

  2. Open-loop wavefront sensing scheme for specimen aberrations correction in two-photon excited fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Aviles-Espinosa, Rodrigo; Andilla, Jordi; Porcar-Guezenec, Rafael; Levecq, Xavier; Artigas, David; Loza-Alvarez, Pablo

    2011-07-01

    The recent linkage between adaptive optics, a technique borrowed from astronomy and various imaging devices, has enabled to push forward their imaging capabilities by improving its contrast and resolution. A specific case is nonlinear microscopy (NLM) that, although it brings several inherent advantages (compared to linear fluorescence techniques) due to its nonlinear dependence on the excitation beam, its enhanced capabilities can be limited by the sample inhomogeneous structure. In this work, we demonstrate how these imaging capabilities can be enhanced by, employing adaptive optics in a two step correction process. Firstly, a closed-loop methodology aided by Shack-Hartman Wavefront sensing scheme is implemented for compensating the aberrations produced by the laser and the optical elements before the high numerical aperture microscope objective, resulting in a one-time calibration process. Then the residual aberrations are produced by the microscope objective and the sample. These are measured in a similar way as it is done in astronomy (employing a laser guide-star), using the two-photon excited fluorescence. The properties of this incoherent emission produced inside a test sample are compared to a genetically modified Caenorhabditis. elegans nematode expressing GFP showing that the emission of this protein (at 810nm) can be sensed efficiently with our WFS by modifying the exposure time. Therefore the recorded wavefront will capture the sample aberrations which are used to shape a deformable mirror in an open-loop configuration. This correction principle is demonstrated in a test sample by correcting aberrations in a "single-shot" resulting in a reduced sample exposure.

  3. On the benefit of aberration-corrected HAADF-STEM for strain determination and its application to tailoring ferroelectric domain patterns.

    PubMed

    Tang, Y L; Zhu, Y L; Ma, X L

    2016-01-01

    Revealing strains on the unit-cell level is essential for understanding the particular performance of materials. Large-scale strain variations with a unit-cell resolution are important for studying ferroelectric materials since the spontaneous polarizations of such materials are strongly coupled with strains. Aberration-corrected high-angle-annular-dark-field scanning transmission electron microscopy (AC-HAADF-STEM) is not so sensitive to the sample thickness and therefore thickness gradients. Consequently it is extremely useful for large-scale strain determination, which can be readily extracted by geometrical phase analysis (GPA). Such a combination has various advantages: it is straightforward, accurate on the unit-cell scale, relatively insensitive to crystal orientation and therefore helpful for large-scale. We take a tetragonal ferroelectric PbTiO3 film as an example in which large-scale strains are determined. Furthermore, based on the specific relationship between lattice rotation and spontaneous polarization (Ps) at 180° domain-walls, the Ps directions are identified, which makes the investigation of ferroelectric domain structures accurate and straightforward. This method is proposed to be suitable for investigating strain-related phenomena in other ferroelectric materials.

  4. Atomic-resolution study of dislocation structures and interfaces in poly-crystalline thin film CdTe using aberration-corrected STEM

    NASA Astrophysics Data System (ADS)

    Paulauskas, Tadas; Colegrove, Eric; Buurma, Chris; Kim, Moon; Klie, Robert

    2014-03-01

    Commercial success of CdTe-based thin film photovoltaic devices stems from its nearly ideal direct band gap which very effectively couples to Sun's light spectrum as well as ease of manufacturing and low cost of these modules. However, to further improve the conversion efficiency beyond 20 percent, it is important to minimize the harmful effects of grain boundaries and lattice defects in CdTe. Direct atomic-scale characterization is needed in order identify the carrier recombination centers. Likewise, it is necessary to confirm that passivants in CdTe, such as Cl, are able to diffuse and bind to the target defects. In this study, we characterize dislocation structures and grain boundaries in poly-crystalline CdTe using aberration-corrected cold-field emission scanning transmission electron microscopy (STEM). The chemical composition of Shockley partial, Frank and Lomer-Cottrell dislocations is examined via atomic column-resolved X-ray energy dispersive (XEDS) and electron energy-loss spectroscopies (EELS). Segregation of Cl towards dislocation cores and grain boundaries is shown in CdCl2 treated samples. We also investigate interfaces in ultra-high-vacuum bonded CdTe bi-crystals with pre-defined misorientation angles which are intended to mimic grain boundaries. Funded by: DOE EERE Sunshot Award EE0005956.

  5. Pulse compressor with aberration correction

    SciTech Connect

    Mankos, Marian

    2015-11-30

    In this SBIR project, Electron Optica, Inc. (EOI) is developing an electron mirror-based pulse compressor attachment to new and retrofitted dynamic transmission electron microscopes (DTEMs) and ultrafast electron diffraction (UED) cameras for improving the temporal resolution of these instruments from the characteristic range of a few picoseconds to a few nanoseconds and beyond, into the sub-100 femtosecond range. The improvement will enable electron microscopes and diffraction cameras to better resolve the dynamics of reactions in the areas of solid state physics, chemistry, and biology. EOI’s pulse compressor technology utilizes the combination of electron mirror optics and a magnetic beam separator to compress the electron pulse. The design exploits the symmetry inherent in reversing the electron trajectory in the mirror in order to compress the temporally broadened beam. This system also simultaneously corrects the chromatic and spherical aberration of the objective lens for improved spatial resolution. This correction will be found valuable as the source size is reduced with laser-triggered point source emitters. With such emitters, it might be possible to significantly reduce the illuminated area and carry out ultrafast diffraction experiments from small regions of the sample, e.g. from individual grains or nanoparticles. During phase I, EOI drafted a set of candidate pulse compressor architectures and evaluated the trade-offs between temporal resolution and electron bunch size to achieve the optimum design for two particular applications with market potential: increasing the temporal and spatial resolution of UEDs, and increasing the temporal and spatial resolution of DTEMs. Specialized software packages that have been developed by MEBS, Ltd. were used to calculate the electron optical properties of the key pulse compressor components: namely, the magnetic prism, the electron mirror, and the electron lenses. In the final step, these results were folded into a model describing the key electron-optical parameters of the complete pulse compressor. The simulations reveal that the mirror pulse compressor can reduce the temporal spread of UEDs and DTEMs to the sub-100 femtosecond level for practical electron bunch sizes. EOI’s pulse compressors can be designed and built to attach to different types of UEDs and DTEMs, thus making them suitable for enhancing the study of the structure, composition, and bonding states of new materials at ultrafast time scales to advance material science research in the field of nanotechnology as well as biomedical research.

  6. Aberration correction of unstable resonators

    NASA Technical Reports Server (NTRS)

    Lang, Robert J. (Inventor)

    1994-01-01

    Construction of aspheric reflectors for unstable resonator lasers to provide an arbitrary laser mode inside the resonator to correct aberrations of an output beam by the construction of the shape of an end reflector opposite the output reflector of the resonator cavity, such as aberrations resulting from refraction of a beam exiting the solid of the resonator having an index of refraction greater than 1 or to produce an aberration in the output beam that will precisely compensate for the aberration of an optical train into which the resonator beam is coupled.

  7. Phase and birefringence aberration correction

    DOEpatents

    Bowers, Mark; Hankla, Allen

    1996-01-01

    A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90.degree. such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation. The two signal beams are focused such that they cross the seed beam path before their respective beam waists in order to achieve BEFWM or the two signal beams are focused to a point or points contained within the focused cone angle of the seed beam to achieve seeded SBS, and thus negate the effects of all birefringent and material aberrations in the system.

  8. Phase and birefringence aberration correction

    DOEpatents

    Bowers, M.; Hankla, A.

    1996-07-09

    A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90{degree} such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation. The two signal beams are focused such that they cross the seed beam path before their respective beam waists in order to achieve BEFWM or the two signal beams are focused to a point or points contained within the focused cone angle of the seed beam to achieve seeded SBS, and thus negate the effects of all birefringent and material aberrations in the system. 5 figs.

  9. New experimental evidences of Au-Cu2S core-shell nanoparticles and atomic resolution imaging by aberration-corrected STEM

    NASA Astrophysics Data System (ADS)

    Khanal, Subarna; Casillas, Gilberto; Bhattarai, Nabraj; Velazquez-Salazar, J. Jesus; Yacaman, Miguel Jose

    2013-03-01

    Au-Cu2S core-shell nanoparticles present different properties than their monometallic counterparts, opening a wide range of possibilities for different applications. Au-Cu2S core-shell nanostructures have raised interest for their many applications in photoelectronic, sensing, catalysis and so on. Au and Au-Cu2S core-shell nanoparticles were prepared by using a modified polyol method. First Au seeds were prepared by reducing HAuCl4.xH2O in ethylene glycol (EG) in the presence of poly(vinylpyrrolidone) (PVP) as a polymer surfactant. Then Cu2S shells were overgrown on Au core seeds by reducing CuSO4 in EG with PVP. The morphology and structural characteristics of Au and Au-Cu2S nanostructures were studied in detail using scanning electron microcopy HITACHI S-5500 and high resolution transmission electron microscope (HRTEM), a resolution 0.19 nm. Moreover, the Cs-corrected scanning transmission electron microscopy (Cs-corrected STEM) technique allowed us to probe the structure at the atomic level of these nanoparticles revealing new structural information. We determined the structure of the four main polyhedral morphologies obtained in the synthesis: decahedral, icosahedral, triangular plates, and rods. This project was supported by grants from the National Center for Research Resources (5 G12RR013646-12) and the National Institute on Minority Health and Health Disparities (G12MD007591).

  10. Coherence gated wavefront sensorless adaptive optics for two photon excited fluorescence retinal imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Jian, Yifan; Cua, Michelle; Bonora, Stefano; Pugh, Edward N.; Zawadzki, Robert J.; Sarunic, Marinko V.

    2016-03-01

    We present a novel system for adaptive optics two photon imaging. We utilize the bandwidth of the femtosecond excitation beam to perform coherence gated imaging (OCT) of the sample. The location of the focus is directly observable in the cross sectional OCT images, and adjusted to the desired depth plane. Next, using real time volumetric OCT, we perform Wavefront Sensorless Adaptive Optics (WSAO) aberration correction using a multi-element adaptive lens capable of correcting up to 4th order Zernike polynomials. The aberration correction is performed based on an image quality metric, for example intensity. The optimization time is limited only by the OCT acquisition rate, and takes ~30s. Following aberration correction, two photon fluorescence images are acquired, and compared to results without adaptive optics correction. This technique is promising for multiphoton imaging in multi-layered, scattering samples such as eye and brain, in which traditional wavefront sensing and guide-star sensorless adaptive optics approaches may not be suitable.

  11. Zonal spherical aberration correction utilizing axial electrodes

    NASA Astrophysics Data System (ADS)

    Chao, Liang C.

    2005-01-01

    Spherical aberration is important in focused ion beam applications where large aperture angles are needed to obtain high beam currents because it results in large tails on the current density distribution. Merwe has shown that for coaxial lenses, negative spherical aberration can be found for rays pass through zonal regions. Merwe"s calculation is valid only for periodic or quasi-periodic lenses and requires a constant axial potential distribution. We have calculated zonal focusing properties of lenses with axial electrodes using nine-point finite difference method and direct ray tracing. Our calculation results indicate that an axial electrode protruding partially into the lens can correct the spherical aberration. When a three-element electrostatic lens is operated at deceleration mode, the introduction of an axial electrode creates zonal regions where the spherical aberration is negative. At deceleration mode, the induced surface charges on the axial electrode have an opposite sign relative to the primary beam. This is in agreement with our previous findings on the study of the correction of spherical aberration utilizing space charges. Same phenomenon was found when an axial electrode is used in conjunction with a cathode lens.

  12. Designing Aberration-Corrected Solid Unstable Resonators

    NASA Technical Reports Server (NTRS)

    Lang, Robert J.

    1994-01-01

    In improved method of designing solid unstable resonator of laser diode, shapes of mirrors calculated to yield specified mode. Ray tracing used to compute shape of initially unspecified end mirror, given shape of initially specified end mirror and specified output mode. No need to accept aberrations or suboptimal circular shapes, to make iterative design computations in effort to converge on desired mode, or to assume paraxiality of rays: Angles between rays and optical axis large, cross sections of surfaces noncircular, and computed shape of end mirror exact. End mirror corrects for all aberrations.

  13. Imaging spectrograph for interstellar shocks: a narrowband imaging payload for the far ultraviolet.

    PubMed

    Beasley, Matthew; Boone, Catherine; Cunningham, Nathaniel; Green, James; Wilkinson, Erik

    2004-08-20

    We present an imaging spectrometer developed for narrowband imaging at 1035 A with high (approximately 1-arc sec) spatial resolution over a modest field of view (approximately 5 arc min). The instrument is based on a conventional Gregorian telescope with aberration-corrected holographic rulings on the secondary optic. These aberration-correcting rulings enable stigmatic imaging in diffracted light with a minimum number of optical elements, thereby maintaining a high system efficiency. The capabilities of this instrument allow us to map the distribution of UV-emitting material in the hot (approximately 300,000 K) plasma from shocks in supernova remnants. Although this design is optimized for imaging near 1035 A, the basic concept can be applied to provide narrowband imaging or long-slit imaging spectroscopy at any wavelength. In addition, a larger field of view is possible with a corresponding loss in spatial resolution. PMID:15352386

  14. Imaging spectrograph for interstellar shocks: a narrowband imaging payload for the far ultraviolet.

    PubMed

    Beasley, Matthew; Boone, Catherine; Cunningham, Nathaniel; Green, James; Wilkinson, Erik

    2004-08-20

    We present an imaging spectrometer developed for narrowband imaging at 1035 A with high (approximately 1-arc sec) spatial resolution over a modest field of view (approximately 5 arc min). The instrument is based on a conventional Gregorian telescope with aberration-corrected holographic rulings on the secondary optic. These aberration-correcting rulings enable stigmatic imaging in diffracted light with a minimum number of optical elements, thereby maintaining a high system efficiency. The capabilities of this instrument allow us to map the distribution of UV-emitting material in the hot (approximately 300,000 K) plasma from shocks in supernova remnants. Although this design is optimized for imaging near 1035 A, the basic concept can be applied to provide narrowband imaging or long-slit imaging spectroscopy at any wavelength. In addition, a larger field of view is possible with a corresponding loss in spatial resolution.

  15. Enhanced diagnostic value for coronary CT angiography of calcified coronary arteries using dual energy and a novel high-Z contrast material: a phantom study

    NASA Astrophysics Data System (ADS)

    Lambert, Jack W.; Ordovas, Karen G.; Sun, Yuxin; Yeh, Benjamin M.

    2016-03-01

    Dual-energy CT is emerging as a dose-saving tool for coronary CT angiography that allows calcium-scoring without the need for a separate unenhanced scan acquisition. Unfortunately the similar attenuation coefficient profiles of iodine and calcium limits the accuracy of their decomposition in the material basis images. We evaluate a tungsten-based contrast material with a more distinct attenuation profile from calcium, and compare its performance to a conventional iodinated agent. We constructed a custom thorax phantom containing simulated sets of vessels 3, 6 and 9 mm in diameter. The vessel sets were walled with concentric and eccentric calcifications ("plaque") with concentrations of 0, 20, 30 and 40% weight calcium hydroxyapatite (HAP). The phantom was filled sequentially with iodine and tungsten contrast material, and scanned helically using a fast-kV-switching DECT scanner. At material decomposition, both iodine and tungsten vessel lumens were separable from the HAP vessel walls, but separation was superior with tungsten which showed minimal false positive signal in the HAP image. Assessing their relative performance using line profiles, the HAP signal was greater in the tungsten separation in 6/9 of the vessel sets, and within 15% of the iodine separation for the remaining 3/9 sets. The robust phantom design enabled systematic evaluation of dual-energy material separation for calcium and a candidate non-iodinated vascular contrast element. This approach can be used to screen further agents and also refine dual energy CT material decomposition approaches.

  16. Optimum HRTEM image contrast at 20 kV and 80 kV--exemplified by graphene.

    PubMed

    Lee, Z; Meyer, J C; Rose, H; Kaiser, U

    2012-01-01

    The dependence of high-resolution transmission electron microscopy (HRTEM) image contrast of graphene on the adjustable parameters of an aberration-corrected microscope operated at 80 and 20 kV has been calculated and, for 80 kV, compared with measurements. We used density functional theory to determine the projected atom potential and obtained the image intensity by averaging over the energy distribution of the imaging electrons, as derived from the electron energy loss spectroscopy measurements. Optimum image contrast has been determined as a function of energy spread of the imaging electrons and chromatic aberration coefficient, showing that significant improvement of contrast can be achieved at 80 kV with the help of a monochromator, however at 20 kV only with chromatic aberration correction and bright atom contrast conditions.

  17. Direct Sub-Angstrom Imaging of a Crystal Lattice

    SciTech Connect

    Nellist, Peter D.; Chisholm, Matthew F; Dellby, N.; Krivanek, O. L.; Murfitt, M. F.; Szilagyi, Z. S.; Lupini, Andrew R; Borisevich, Albina Y; Sides, Jr., William H.; Pennycook, Stephen J

    2004-01-01

    Despite the use of electrons with wavelengths of just a few picometers, spatial resolution in a transmission electron microscope (TEM) has been limited by spherical aberration to typically around 0.15 nanometer. Individual atomic columns in a crystalline lattice can therefore only be imaged for a few low-order orientations, limiting the range of defects that can be imaged at atomic resolution. The recent development of spherical aberration correctors for transmission electron microscopy allows this limit to be overcome. We present direct images from an aberration-corrected scanning TEM that resolve a lattice in which the atomic columns are separated by less than 0.1 nanometer.

  18. Eigenfunction analysis of stochastic backscatter for characterization of acoustic aberration in medical ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Varslot, Trond; Krogstad, Harald; Mo, Eirik; Angelsen, Bjørn A.

    2004-06-01

    Presented here is a characterization of aberration in medical ultrasound imaging. The characterization is optimal in the sense of maximizing the expected energy in a modified beamformer output of the received acoustic backscatter. Aberration correction based on this characterization takes the form of an aberration correction filter. The situation considered is frequently found in applications when imaging organs through a body wall: aberration is introduced in a layer close to the transducer, and acoustic backscatter from a scattering region behind the body wall is measured at the transducer surface. The scattering region consists of scatterers randomly distributed with very short correlation length compared to the acoustic wavelength of the transmit pulse. The scatterer distribution is therefore assumed to be δ correlated. This paper shows how maximizing the expected energy in a modified beamformer output signal naturally leads to eigenfunctions of a Fredholm integral operator, where the associated kernel function is a spatial correlation function of the received stochastic signal. Aberration characterization and aberration correction are presented for simulated data constructed to mimic aberration introduced by the abdominal wall. The results compare well with what is obtainable using data from a simulated point source.

  19. Modeling of Optical Aberration Correction using a Liquid Crystal Device

    NASA Technical Reports Server (NTRS)

    Xinghua, Wang; Bin, Wang; McManamon, Paul F.; Pouch, John J.; Miranda, Felix A.

    2006-01-01

    Gruneisen (sup 1-3), has shown that small, light weight, liquid crystal based devices can correct for the optical distortion caused by an imperfect primary mirror in a telescope and has discussed the efficiency of this correction. In this paper we expand on that work and propose a semi-analytical approach for quantifying the efficiency of a liquid crystal based wavefront corrector for this application.

  20. Successive optimization for fast-phase aberration correction

    NASA Astrophysics Data System (ADS)

    Farouk, Zyad; Youssef, Abou-Bakr M.; Kadah, Yasser M.

    2003-05-01

    We propose two new methods that allow the determination of the phase delays corresponding to phase aberration efficiently. We derive a new optimization methodology to compute the best compensation phase delays in successive steps. In particular, we start with an array consisting of one element with a specific excitation pattern. Then, another element is added and the dynamic receive delays are iteratively computed such that the obtained echoes are optimal in strength. A third element is added and the process is repeated. This process continues until all elements in the aperture are added. Hence, instead of solving the conventional N-dimensional problem of adjusting the delays of N elements together to achieve optimal characteristics, we transform the problem into the one of solving N-1 consecutive one-dimensional optimization problems. Given the fact that the set of available delay values is finite, the one-dimensional problem is shown to be a classical combinatorial optimization problem. The other technique based on Fourier transform tries to align signals based on information from a single frequency selected as the center frequency of the probe. This method is simple, computationally efficient and lends itself to real-time implementation. The proposed methods were implemented to correct real data from a resolution phantom and the results particularly indicate the potential of the second method.

  1. Aberration corrected STEM to study an ancient hair dyeing formula

    NASA Astrophysics Data System (ADS)

    Patriarche, G.; Van Elslande, E.; Castaing, J.; Walter, P.

    2014-05-01

    Lead-based chemistry was initiated in ancient Egypt for cosmetic preparation more than 4000 years ago. Here, we study a hair-dyeing recipe using lead salts described in text since Greco-Roman times. We report direct evidence about the shape and distribution of PbS nanocrystals that form within the hair during blackening.

  2. Simultaneous Multiplane Imaging with a Distorted Diffraction Grating

    NASA Astrophysics Data System (ADS)

    Blanchard, Paul M.; Greenaway, Alan H.

    1999-11-01

    We describe a simple technique for simultaneously imaging multiple layers within an object field onto a single camera. The approach uses a binary diffraction grating in which the lines are distorted such that a different level of defocus is associated with each diffraction order. The design of the gratings is discussed, and their ability to image multiple object planes is validated experimentally. Extension of the technique for spherical-aberration correction is described, and it is shown how the gratings can be used as part of a wave-front sensing system.

  3. STEM Imaging of Single Pd Atoms in Activated Carbon Fibers Considered for Hydrogen Storage

    SciTech Connect

    Van Benthem, Klaus; Bonifacio, Cecile S; Contescu, Cristian I; Pennycook, Stephen J; Gallego, Nidia C

    2011-01-01

    Aberration corrected scanning transmission electron microscopy was used to demonstrate the feasibility of imaging individual Pd atoms that are highly dispersed throughout the volume of activated carbon fibers. Simultaneous acquisition of high-angle annular dark-field and bright-field images allows correlation of the location of single Pd atoms with microstructural features of the carbon host material. Sub-Angstrom imaging conditions revealed that 18 wt% of the total Pd content is dispersed as single Pd atoms in three re-occurring local structural arrangements. The identified structural configurations may represent effective storage sites for molecular hydrogen through Kubas complex formation as discussed in detail in the preceding article.

  4. Electron dose dependence of signal-to-noise ratio, atom contrast and resolution in transmission electron microscope images.

    PubMed

    Lee, Z; Rose, H; Lehtinen, O; Biskupek, J; Kaiser, U

    2014-10-01

    In order to achieve the highest resolution in aberration-corrected (AC) high-resolution transmission electron microscopy (HRTEM) images, high electron doses are required which only a few samples can withstand. In this paper we perform dose-dependent AC-HRTEM image calculations, and study the dependence of the signal-to-noise ratio, atom contrast and resolution on electron dose and sampling. We introduce dose-dependent contrast, which can be used to evaluate the visibility of objects under different dose conditions. Based on our calculations, we determine optimum samplings for high and low electron dose imaging conditions.

  5. Electron dose dependence of signal-to-noise ratio, atom contrast and resolution in transmission electron microscope images.

    PubMed

    Lee, Z; Rose, H; Lehtinen, O; Biskupek, J; Kaiser, U

    2014-10-01

    In order to achieve the highest resolution in aberration-corrected (AC) high-resolution transmission electron microscopy (HRTEM) images, high electron doses are required which only a few samples can withstand. In this paper we perform dose-dependent AC-HRTEM image calculations, and study the dependence of the signal-to-noise ratio, atom contrast and resolution on electron dose and sampling. We introduce dose-dependent contrast, which can be used to evaluate the visibility of objects under different dose conditions. Based on our calculations, we determine optimum samplings for high and low electron dose imaging conditions. PMID:24566042

  6. Correction of birefringence and thermal lensing in nonreciprocal resonators by use of a dynamic imaging mirror.

    PubMed

    Moshe, I; Jackel, S

    2000-08-20

    Enhanced correction of thermally induced birefringence in the presence of strong single-pass, azimuthally dependent bipolar focusing was achieved in single-rod laser oscillators by use of an adaptive optic rear mirror with image relay and aberration correction capabilities. Together with a Faraday rotator, the imaging variable radius mirror was successfully tested in stable and unstable Nd:Cr:GSGG power oscillators under variable pump power conditions from 0 to 800 W. Birefringence correction in the absence of ray retracing was achieved. PMID:18350015

  7. Statistical analysis of support thickness and particle size effects in HRTEM imaging of metal nanoparticles.

    PubMed

    House, Stephen D; Bonifacio, Cecile S; Grieshaber, Ross V; Li, Long; Zhang, Zhongfan; Ciston, Jim; Stach, Eric A; Yang, Judith C

    2016-10-01

    High-resolution transmission electron microscopy (HRTEM) examination of nanoparticles requires their placement on some manner of support - either TEM grid membranes or part of the material itself, as in many heterogeneous catalyst systems - but a systematic quantification of the practical imaging limits of this approach has been lacking. Here we address this issue through a statistical evaluation of how nanoparticle size and substrate thickness affects the ability to resolve structural features of interest in HRTEM images of metallic nanoparticles on common support membranes. The visibility of lattice fringes from crystalline Au nanoparticles on amorphous carbon and silicon supports of varying thickness was investigated with both conventional and aberration-corrected TEM. Over the 1-4nm nanoparticle size range examined, the probability of successfully resolving lattice fringes differed significantly as a function both of nanoparticle size and support thickness. Statistical analysis was used to formulate guidelines for the selection of supports and to quantify the impact a given support would have on HRTEM imaging of crystalline structure. For nanoparticles ≥1nm, aberration-correction was found to provide limited benefit for the purpose of visualizing lattice fringes; electron dose is more predictive of lattice fringe visibility than aberration correction. These results confirm that the ability to visualize lattice fringes is ultimately dependent on the signal-to-noise ratio of the HRTEM images, rather than the point-to-point resolving power of the microscope. This study provides a benchmark for HRTEM imaging of crystalline supported metal nanoparticles and is extensible to a wide variety of supports and nanostructures. PMID:27421079

  8. Three-Dimensional Imaging of Individual Hafnium Atoms Inside a Semiconductor Device

    SciTech Connect

    van Benthem, Klaus; Lupini, Andrew R; Kim, Miyoung; Baik, Hion Suck; Doh, SeokJoo; Lee, Jong-Hoo; Oxley, Mark P; Findlay, Scott D.; Luck, Julia T; Pennycook, Stephen J

    2005-01-01

    The aberration-corrected scanning transmission electron microscope allows probes to be formed with less than 1-{angstrom} diameter, providing sufficient sensitivity to observe individual Hf atoms within the SiO{sub 2} passivating layer of a HfO{sub 2}/SiO{sub 2}/Si alternative gate dielectric stack. Furthermore, the depth resolution is sufficient to localize the atom positions to half-nanometer precision in the third dimension. From a through-focal series of images, we demonstrate a three-dimensional reconstruction of the Hf atom sites, representing a three-dimensional map of potential breakdown sites within the gate dielectric.

  9. Design of an integrated hardware interface for AOSLO image capture and cone-targeted stimulus delivery

    PubMed Central

    Yang, Qiang; Arathorn, David W.; Tiruveedhula, Pavan; Vogel, Curtis R.; Roorda, Austin

    2010-01-01

    We demonstrate an integrated FPGA solution to project highly stabilized, aberration-corrected stimuli directly onto the retina by means of real-time retinal image motion signals in combination with high speed modulation of a scanning laser. By reducing the latency between target location prediction and stimulus delivery, the stimulus location accuracy, in a subject with good fixation, is improved to 0.15 arcminutes from 0.26 arcminutes in our earlier solution. We also demonstrate the new FPGA solution is capable of delivering stabilized large stimulus pattern (up to 256x256 pixels) to the retina. PMID:20721171

  10. Atomic resolution ADF-STEM imaging of organic molecular crystal of halogenated copper phthalocyanine.

    PubMed

    Haruta, Mitsutaka; Yoshida, Kaname; Kurata, Hiroki; Isoda, Seiji

    2008-05-01

    Annular dark-field (ADF) scanning transmission electron microscopy (STEM) measurements are demonstrated for the first time to be applicable for acquiring Z-contrast images of organic molecules at atomic resolution. High-angle ADF imaging by STEM is a new technique that provides incoherent high-resolution Z-contrast images for organic molecules. In the present study, low-angle ADF-STEM is successfully employed to image the molecular crystal structure of hexadecachloro-Cu-phthalocyanine (Cl16-CuPc), an organic molecule. The structures of CuPc derivatives (polyhalogenated CuPc with Br and Cl) are determined quantitatively using the same technique to determine the occupancy of halogens at each chemical site. By comparing the image contrasts of atomic columns, the occupancy of Br is found to be ca. 56% at the inner position, slightly higher than that for random substitution and in good agreement with previous TEM results.

  11. A new MEMS-based system for ultra-high-resolution imaging at elevated temperatures.

    PubMed

    Allard, Lawrence F; Bigelow, Wilbur C; Jose-Yacaman, Miguel; Nackashi, David P; Damiano, John; Mick, Stephen E

    2009-03-01

    In recent years, an increasing number of laboratories have been applying in situ heating (and ultimately, gas reaction) techniques in electron microscopy studies of catalysts and other nanophase materials. With the advent of aberration-corrected electron microscopes that provide sub-Angström image resolution, it is of great interest to study the behavior of materials at elevated temperatures while maintaining the resolution capabilities of the microscope. In collaboration with Protochips Inc., our laboratory is developing an advanced capability for in situ heating experiments that overcomes a number of performance problems with standard heating stage technologies. The new heater device allows, for example, temperature cycling from room temperature to greater than 1000 degrees C in 1 ms (a heating rate of 1 million Centigrade degrees per second) and cooling at nearly the same rate. It also exhibits a return to stable operation (drift controlled by the microscope stage, not the heater) in a few seconds after large temperature excursions. With Protochips technology, we were able to demonstrate single atom imaging and the behavior of nanocrystals at high temperatures, using high-angle annular dark-field imaging in an aberration-corrected (S)TEM. The new capability has direct applicability for remote operation and (ultimately) for gas reaction experiments using a specially designed environmental cell.

  12. [Design and analysis of a novel light visible spectrum imaging spectrograph optical system].

    PubMed

    Shen, Man-de; Li, Fei; Zhou, Li-bing; Li, Cheng; Ren, Huan-huan; Jiang, Qing-xiu

    2015-02-01

    A novel visible spectrum imaging spectrograph optical system was proposed based on the negative dispersion, the arbitrary phase modulation characteristics of diffractive optical element and the aberration correction characteristics of freeform optical element. The double agglutination lens was substituted by a hybrid refractive/diffractive lens based on the negative dispersion of diffractive optical element. Two freeform optical elements were used in order to correct some aberration based on the aberration correction characteristics of freeform optical element. An example and frondose design process were presented. When the design parameters were uniform, compared with the traditional system, the novel visible spectrum imaging spectrograph optical system's weight was reduced by 22.9%, the total length was reduced by 26.6%, the maximal diameter was reduced by 30.6%, and the modulation transfer function (MTF) in 1.0 field-of-view was improved by 0.35 with field-of-view improved maximally. The maximal distortion was reduced by 1.6%, the maximal longitudinal aberration was reduced by 56.4%, and the lateral color aberration was reduced by 59. 3%. From these data, we know that the performance of the novel system was advanced quickly and it could be used to put forward a new idea for modern visible spectrum imaging spectrograph optical system design.

  13. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging.

    PubMed

    Cua, Michelle; Wahl, Daniel J; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J; Jian, Yifan; Sarunic, Marinko V

    2016-09-07

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems.

  14. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging

    NASA Astrophysics Data System (ADS)

    Cua, Michelle; Wahl, Daniel J.; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J.; Jian, Yifan; Sarunic, Marinko V.

    2016-09-01

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems.

  15. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging.

    PubMed

    Cua, Michelle; Wahl, Daniel J; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J; Jian, Yifan; Sarunic, Marinko V

    2016-01-01

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems. PMID:27599635

  16. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging

    PubMed Central

    Cua, Michelle; Wahl, Daniel J.; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J.; Jian, Yifan; Sarunic, Marinko V.

    2016-01-01

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems. PMID:27599635

  17. Adaptive optics and phase diversity imaging for responsive space applications.

    SciTech Connect

    Smith, Mark William; Wick, David Victor

    2004-11-01

    The combination of phase diversity and adaptive optics offers great flexibility. Phase diverse images can be used to diagnose aberrations and then provide feedback control to the optics to correct the aberrations. Alternatively, phase diversity can be used to partially compensate for aberrations during post-detection image processing. The adaptive optic can produce simple defocus or more complex types of phase diversity. This report presents an analysis, based on numerical simulations, of the efficiency of different modes of phase diversity with respect to compensating for specific aberrations during post-processing. It also comments on the efficiency of post-processing versus direct aberration correction. The construction of a bench top optical system that uses a membrane mirror as an active optic is described. The results of characterization tests performed on the bench top optical system are presented. The work described in this report was conducted to explore the use of adaptive optics and phase diversity imaging for responsive space applications.

  18. Image simulation for electron energy loss spectroscopy

    SciTech Connect

    Oxley, Mark P.; Pennycook, Stephen J.

    2007-10-22

    In this paper, aberration correction of the probe forming optics of the scanning transmission electron microscope has allowed the probe-forming aperture to be increased in size, resulting in probes of the order of 1 Å in diameter. The next generation of correctors promise even smaller probes. Improved spectrometer optics also offers the possibility of larger electron energy loss spectrometry detectors. The localization of images based on core-loss electron energy loss spectroscopy is examined as function of both probe-forming aperture and detector size. The effective ionization is nonlocal in nature, and two common local approximations are compared to full nonlocal calculations. Finally, the affect of the channelling of the electron probe within the sample is also discussed.

  19. Image simulation for electron energy loss spectroscopy

    DOE PAGES

    Oxley, Mark P.; Pennycook, Stephen J.

    2007-10-22

    In this paper, aberration correction of the probe forming optics of the scanning transmission electron microscope has allowed the probe-forming aperture to be increased in size, resulting in probes of the order of 1 Å in diameter. The next generation of correctors promise even smaller probes. Improved spectrometer optics also offers the possibility of larger electron energy loss spectrometry detectors. The localization of images based on core-loss electron energy loss spectroscopy is examined as function of both probe-forming aperture and detector size. The effective ionization is nonlocal in nature, and two common local approximations are compared to full nonlocal calculations.more » Finally, the affect of the channelling of the electron probe within the sample is also discussed.« less

  20. Atomic-scale imaging and spectroscopy for in situ liquid scanning transmission electron microscopy.

    PubMed

    Jungjohann, Katherine L; Evans, James E; Aguiar, Jeffery A; Arslan, Ilke; Browning, Nigel D

    2012-06-01

    Observation of growth, synthesis, dynamics, and electrochemical reactions in the liquid state is an important yet largely unstudied aspect of nanotechnology. The only techniques that can potentially provide the insights necessary to advance our understanding of these mechanisms is simultaneous atomic-scale imaging and quantitative chemical analysis (through spectroscopy) under environmental conditions in the transmission electron microscope. In this study we describe the experimental and technical conditions necessary to obtain electron energy loss (EEL) spectra from a nanoparticle in colloidal suspension using aberration-corrected scanning transmission electron microscopy (STEM) combined with the environmental liquid stage. At a fluid path length below 400 nm, atomic resolution images can be obtained and simultaneous compositional analysis can be achieved. We show that EEL spectroscopy can be used to quantify the total fluid path length around the nanoparticle and demonstrate that characteristic core-loss signals from the suspended nanoparticles can be resolved and analyzed to provide information on the local interfacial chemistry with the surrounding environment. The combined approach using aberration-corrected STEM and EEL spectra with the in situ fluid stage demonstrates a plenary platform for detailed investigations of solution-based catalysis. PMID:22640968

  1. Atomic-Scale Imaging and Spectroscopy for In Situ Liquid Scanning Transmission Electron Microscopy

    SciTech Connect

    Jungjohann, K. L.; Evans, James E.; Aguiar, Jeff; Arslan, Ilke; Browning, Nigel D.

    2012-06-04

    Observation of growth, synthesis, dynamics and electrochemical reactions in the liquid state is an important yet largely unstudied aspect of nanotechnology. The only techniques that can potentially provide the insights necessary to advance our understanding of these mechanisms is simultaneous atomic-scale imaging and quantitative chemical analysis (through spectroscopy) under environmental conditions in the transmission electron microscope (TEM). In this study we describe the experimental and technical conditions necessary to obtain electron energy loss (EEL) spectra from a nanoparticle in colloidal suspension using aberration corrected scanning transmission electron microscopy (STEM) combined with the environmental liquid stage. At a fluid path length below 400 nm, atomic resolution images can be obtained and simultaneous compositional analysis can be achieved. We show that EEL spectroscopy can be used to quantify the total fluid path length around the nanoparticle, and demonstrate characteristic core-loss signals from the suspended nanoparticles can be resolved and analyzed to provide information on the local interfacial chemistry with the surrounding environment. The combined approach using aberration corrected STEM and EEL spectra with the in situ fluid stage demonstrates a plenary platform for detailed investigations of solution based catalysis and biological research.

  2. Atomic-scale imaging and spectroscopy for in situ liquid scanning transmission electron microscopy.

    PubMed

    Jungjohann, Katherine L; Evans, James E; Aguiar, Jeffery A; Arslan, Ilke; Browning, Nigel D

    2012-06-01

    Observation of growth, synthesis, dynamics, and electrochemical reactions in the liquid state is an important yet largely unstudied aspect of nanotechnology. The only techniques that can potentially provide the insights necessary to advance our understanding of these mechanisms is simultaneous atomic-scale imaging and quantitative chemical analysis (through spectroscopy) under environmental conditions in the transmission electron microscope. In this study we describe the experimental and technical conditions necessary to obtain electron energy loss (EEL) spectra from a nanoparticle in colloidal suspension using aberration-corrected scanning transmission electron microscopy (STEM) combined with the environmental liquid stage. At a fluid path length below 400 nm, atomic resolution images can be obtained and simultaneous compositional analysis can be achieved. We show that EEL spectroscopy can be used to quantify the total fluid path length around the nanoparticle and demonstrate that characteristic core-loss signals from the suspended nanoparticles can be resolved and analyzed to provide information on the local interfacial chemistry with the surrounding environment. The combined approach using aberration-corrected STEM and EEL spectra with the in situ fluid stage demonstrates a plenary platform for detailed investigations of solution-based catalysis.

  3. Efficient phase contrast imaging in STEM using a pixelated detector. Part 1: experimental demonstration at atomic resolution.

    PubMed

    Pennycook, Timothy J; Lupini, Andrew R; Yang, Hao; Murfitt, Matthew F; Jones, Lewys; Nellist, Peter D

    2015-04-01

    We demonstrate a method to achieve high efficiency phase contrast imaging in aberration corrected scanning transmission electron microscopy (STEM) with a pixelated detector. The pixelated detector is used to record the Ronchigram as a function of probe position which is then analyzed with ptychography. Ptychography has previously been used to provide super-resolution beyond the diffraction limit of the optics, alongside numerically correcting for spherical aberration. Here we rely on a hardware aberration corrector to eliminate aberrations, but use the pixelated detector data set to utilize the largest possible volume of Fourier space to create high efficiency phase contrast images. The use of ptychography to diagnose the effects of chromatic aberration is also demonstrated. Finally, the four dimensional dataset is used to compare different bright field detector configurations from the same scan for a sample of bilayer graphene. Our method of high efficiency ptychography produces the clearest images, while annular bright field produces almost no contrast for an in-focus aberration-corrected probe.

  4. Novel MEMS-based gas-cell/heating specimen holder provides advanced imaging capabilities for in situ reaction studies.

    PubMed

    Allard, Lawrence F; Overbury, Steven H; Bigelow, Wilbur C; Katz, Michael B; Nackashi, David P; Damiano, John

    2012-08-01

    In prior research, specimen holders that employ a novel MEMS-based heating technology (Aduro™) provided by Protochips Inc. (Raleigh, NC, USA) have been shown to permit sub-Ångström imaging at elevated temperatures up to 1,000°C during in situ heating experiments in modern aberration-corrected electron microscopes. The Aduro heating devices permit precise control of temperature and have the unique feature of providing both heating and cooling rates of 10⁶°C/s. In the present work, we describe the recent development of a new specimen holder that incorporates the Aduro heating device into a "closed-cell" configuration, designed to function within the narrow (2 mm) objective lens pole piece gap of an aberration-corrected JEOL 2200FS STEM/TEM, and capable of exposing specimens to gases at pressures up to 1 atm. We show the early results of tests of this specimen holder demonstrating imaging at elevated temperatures and at pressures up to a full atmosphere, while retaining the atomic resolution performance of the microscope in high-angle annular dark-field and bright-field imaging modes.

  5. Efficient phase contrast imaging in STEM using a pixelated detector. Part 1: Experimental demonstration at atomic resolution

    DOE PAGES

    Pennycook, Timothy J.; Lupini, Andrew R.; Yang, Hao; Murfitt, Matthew F.; Jones, Lewys; Nellist, Peter D.

    2014-10-15

    In this paper, we demonstrate a method to achieve high efficiency phase contrast imaging in aberration corrected scanning transmission electron microscopy (STEM) with a pixelated detector. The pixelated detector is used to record the Ronchigram as a function of probe position which is then analyzed with ptychography. Ptychography has previously been used to provide super-resolution beyond the diffraction limit of the optics, alongside numerically correcting for spherical aberration. Here we rely on a hardware aberration corrector to eliminate aberrations, but use the pixelated detector data set to utilize the largest possible volume of Fourier space to create high efficiency phasemore » contrast images. The use of ptychography to diagnose the effects of chromatic aberration is also demonstrated. In conclusion, the four dimensional dataset is used to compare different bright field detector configurations from the same scan for a sample of bilayer graphene. Our method of high efficiency ptychography produces the clearest images, while annular bright field produces almost no contrast for an in-focus aberration-corrected probe.« less

  6. Efficient phase contrast imaging in STEM using a pixelated detector. Part 1: Experimental demonstration at atomic resolution

    SciTech Connect

    Pennycook, Timothy J.; Lupini, Andrew R.; Yang, Hao; Murfitt, Matthew F.; Jones, Lewys; Nellist, Peter D.

    2014-10-15

    In this paper, we demonstrate a method to achieve high efficiency phase contrast imaging in aberration corrected scanning transmission electron microscopy (STEM) with a pixelated detector. The pixelated detector is used to record the Ronchigram as a function of probe position which is then analyzed with ptychography. Ptychography has previously been used to provide super-resolution beyond the diffraction limit of the optics, alongside numerically correcting for spherical aberration. Here we rely on a hardware aberration corrector to eliminate aberrations, but use the pixelated detector data set to utilize the largest possible volume of Fourier space to create high efficiency phase contrast images. The use of ptychography to diagnose the effects of chromatic aberration is also demonstrated. In conclusion, the four dimensional dataset is used to compare different bright field detector configurations from the same scan for a sample of bilayer graphene. Our method of high efficiency ptychography produces the clearest images, while annular bright field produces almost no contrast for an in-focus aberration-corrected probe.

  7. Atomic resolution imaging of graphene by transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Robertson, Alex W.; Warner, Jamie H.

    2013-05-01

    The atomic structure of a material influences its electronic, chemical, magnetic and mechanical properties. Characterising carbon nanomaterials, such as fullerenes, nanotubes and graphene, at the atomic level is challenging due to their chemical reactivity and low atomic mass. Transmission electron microscopy and scanning probe microscopy are two of the leading methods for imaging graphene at the atomic level. Here, we report on recent advances in atomic resolution imaging of graphene using aberration-corrected high resolution transmission electron microscopy and how it has revealed many of the structural deviations from the pristine monolayer form. Structures in graphene such as vacancy defects, edges, grain boundaries, linear chains, impurity dopants, layer number, layer stacking and bond rotations are explored.

  8. Modeling atomic-resolution scanning transmission electron microscopy images.

    PubMed

    Findlay, Scott D; Oxley, Mark P; Allen, Leslie J

    2008-02-01

    A real-space description of inelastic scattering in scanning transmission electron microscopy is derived with particular attention given to the implementation of the projected potential approximation. A hierarchy of approximations to expressions for inelastic images is presented. Emphasis is placed on the conditions that must hold in each case. The expressions that justify the most direct, visual interpretation of experimental data are also the most approximate. Therefore, caution must be exercised in selecting experimental parameters that validate the approximations needed for the analysis technique used. To make the most direct, visual interpretation of electron-energy-loss spectroscopic images from core-shell excitations requires detector improvements commensurate with those that aberration correction provides for the probe-forming lens. Such conditions can be relaxed when detailed simulations are performed as part of the analysis of experimental data. PMID:18096101

  9. Modelling atomic resolution scanning transmission electron microscopy images

    SciTech Connect

    Findlay, Scott D.; Oxley, Mark P; Allen, L. J.

    2008-01-01

    A real-space description of inelastic scattering in scanning transmission electron microscopy is derived with particular attention given to the implementation of the projected potential approximation. A hierarchy of approximations to expressions for inelastic images is presented. Emphasis is placed on the conditions that must hold in each case. The expressions that justify the most direct, visual interpretation of experimental data are also the most approximate. Therefore, caution must be exercised in selecting experimental parameters that validate the approximations needed for the analysis technique used. To make the most direct, visual interpretation of electron-energy-loss spectroscopic images from core-shell excitations requires detector improvements commensurate with those that aberration correction provides for the probe-forming lens. Such conditions can be relaxed when detailed simulations are performed as part of the analysis of experimental data.

  10. Atomic-level imaging of Mo-V-O complex oxide phase intergrowth, grain boundaries, and defects using HAADF-STEM.

    PubMed

    Pyrz, William D; Blom, Douglas A; Sadakane, Masahiro; Kodato, Katsunori; Ueda, Wataru; Vogt, Thomas; Buttrey, Douglas J

    2010-04-01

    In this work, we structurally characterize defects, grain boundaries, and intergrowth phases observed in various Mo-V-O materials using aberration-corrected high-angle annular dark-field (HAADF) imaging within a scanning transmission electron microscope (STEM). Atomic-level imaging of these preparations clearly shows domains of the orthorhombic M1-type phase intergrown with the trigonal phase. Idealized models based on HAADF imaging indicate that atomic-scale registry at the domain boundaries can be seamless with several possible trigonal and M1-type unit cell orientation relationships. The alignment of two trigonal domains separated by an M1-type domain or vice versa can be predicted by identifying the number of rows/columns of parallel symmetry operators. Intergrowths of the M1 catalyst with the M2 phase or with the Mo(5)O(14)-type phase have not been observed. The resolution enhancements provided by aberration-correction have provided new insights to the understanding of phase equilibria of complex Mo-V-O materials. This study exemplifies the utility of STEM for the characterization of local structure at crystalline phase boundaries.

  11. Fluorine in shark teeth: its direct atomic-resolution imaging and strengthening function.

    PubMed

    Chen, Chunlin; Wang, Zhongchang; Saito, Mitsuhiro; Tohei, Tetsuya; Takano, Yoshiro; Ikuhara, Yuichi

    2014-02-01

    Atomic-resolution imaging of beam-sensitive biominerals is extremely challenging, owing to their fairly complex structures and the damage caused by electron irradiation. Herein, we overcome these difficulties by performing aberration-corrected electron microscopy with low-dose imaging techniques, and report the successful direct atomic-resolution imaging of every individual atomic column in the complex fluorapatite structure of shark tooth enameloid, which can be of paramount importance for teeth in general. We demonstrate that every individual atomic column in shark tooth enameloid can be spatially resolved, and has a complex fluorapatite structure. Furthermore, ab initio calculations show that fluorine atoms can be covalently bound to the surrounding calcium atoms, which improves understanding of their caries-reducing effects in shark teeth.

  12. Imaging Spectrometers Using Concave Holographic Gratings

    NASA Technical Reports Server (NTRS)

    Gradie, J.; Wang, S.

    1993-01-01

    Imaging spectroscopy combines the spatial attributes of imaging with the compositionally diagnostic attributes of spectroscopy. For spacebased remote sensing applications, mass, size, power, data rate, and application constrain the scanning approach. For the first three approaches, substantial savings in mass and size of the spectrometer can be achieved in some cases with a concave holographic grating and careful placement of an order-sorting filter. A hologram etched on the single concave surface contains the equivalent of the collimating, dispersing, and camera optics of a conventional grating spectrometer and provides substantial wavelength dependent corrections for spherical aberrations and a flat focal field. These gratings can be blazed to improve efficiency when used over a small wavelength range or left unblazed for broadband uniform efficiency when used over a wavelength range of up to 2 orders. More than 1 order can be imaged along the dispersion axis by placing an appropriately designed step order-sorting filter in front of the one- or two-dimensional detector. This filter can be shaped for additional aberration corrections. The VIRIS imaging spectrometer based on the broadband design provides simultaneous imaging of the entrance slit from lambda = 0.9 to 2.6 microns (1.5 orders) onto a 128 x 128 HgCdTe detector (at 77 K). The VIRIS spectrometer was used for lunar mapping with the UH 24.in telescope at Mauna Kea Observatory. The design is adaptable for small, low mass, space based imaging spectrometers.

  13. On the visibility of "heavy" atoms in dark-field STEM

    NASA Astrophysics Data System (ADS)

    Shannon, M. D.; Nellist, P. D.; Nicolosi, V.; Shannon, G. B.; Shmeliov, A.

    2012-07-01

    One of the most useful and apparently straightforward attributes of annular dark-field (ADF) STEM imaging is the ability to image heavy atoms on relatively light substrates using Z-contrast (High-Angle ADF) imaging. From multislice calculations, however, some isolated heavy atoms, e.g. Re, can go undetected in a thin Co matrix in standard aberration-corrected HAADF-STEM imaging of catalyst nanoparticles oriented accurately on a zone-axis [2]. More recently simultaneous Medium-Angle and High-Angle ADF imaging of a few layers of BN has shown experimentally that some adatoms are invisible in MAADF whilst exhibiting very strong contrast in HAADF. Simulations confirm that this can occur for atoms such as sodium. In both situations HOLZ ring imaging can be used to extract additional information.

  14. Imaging performance of elliptical-boundary varifocal mirrors in active optical systems

    NASA Astrophysics Data System (ADS)

    Lukes, Sarah Jane

    Micro-electro-mechanical systems deformable-membrane mirrors provide a means of focus control and attendant spherical aberration correction for miniaturized imaging systems. The technology has greatly advanced in the last decade, thereby extending their focal range capabilities. This dissertation describes a novel SU-8 2002 silicon-on-insulator wafer deformable mirror. A 4.000 mm x 5.657 mm mirror for 45o incident light rays achieves 22 mum stroke or 65 diopters, limited by snapdown. The mirrors show excellent optical quality while flat. Most have peak-to-valley difference of less than 150 nm and root-mean-square less than 25 nm. The process proves simple, only requiring a silicon-on-insulator wafer, SU-8 2002, and a metal layer. Xenon difluoride etches the silicon to release the mirrors. Greater than 90% of the devices survive fabrication and release. While current literature includes several aberration analyses on static mirrors, analyses that incorporate the dynamic nature of these mirrors do not exist. Optical designers may have a choice between deformable mirrors and other types of varifocal mirrors or lenses. Furthermore, a dynamic mirror at an incidence angle other than normal may be desired due to space limitations or for higher throughput (normal incidence requires a beam splitter). This dissertation presents an analysis based on the characteristic function of the system. It provides 2nd and 3rd order aberration coefficients in terms of dynamic focus range and base ray incidence angle. These afford an understanding of the significance of different types of aberrations. Root-mean-square and Strehl calculations provide insight into overall imaging performance for various conditions. I present general guidelines for maximum incidence angle and field of fiew that provide near diffraction-limited performance. Experimental verification of the MEMS mirrors at 5o and 45o incidence angles validates the analytical results. A Blu-ray optical pick-up imaging

  15. Characteristics of the retinal images of the eye optical systems with implanted intraocular lenses

    NASA Astrophysics Data System (ADS)

    Siedlecki, Damian; Zając, Marek; Nowak, Jerzy

    2007-04-01

    Cataract, or opacity of crystalline lens in the human eye is one of the most frequent reasons of blindness nowadays. Removing the pathologically altered crystalline lens and replacing it with artificial implantable intraocular lens (IOL) is practically the only therapy in this illness. There exist a wide variety of artificial IOL types on the medical market, differing in their material and design (shape). In this paper six exemplary models of IOL's made of PMMA, acrylic and silicone are considered. The retinal image quality is analyzed numerically on the basis of Liou-Brennan eye model with these IOL's inserted. Chromatic aberration as well as polychromatic Point Spread Function and Modulation Transfer Function are calculated as most adequate image quality measures. The calculations made with Zemax TM software show the importance of chromatic aberration correction.

  16. Progress on developing wavefront sensorless adaptive optics optical coherence tomography for in vivo retinal imaging in mice

    NASA Astrophysics Data System (ADS)

    Zam, Azhar; Zhang, Pengfei; Jian, Yifan; Sarunic, Marinko V.; Bonora, Stefano; Pugh, Edward N.; Zawadzki, Robert J.

    2015-03-01

    We present a new design for a wavefront sensorless adaptive optics (WS-AO) Fourier domain optical coherence tomography (FD-OCT) system for small animal retinal imaging in vivo. Without the optical complications necessary for inclusion of a wavefront sensor in the optical system, this version of WS-AO FD-OCT system has a simplified optical design, including elimination of long focal length scanning optics and optical conjugation of vertical and horizontal scanners. This modification provides a modular large Field of View for retinal screening (25 degree visual angle), while also allowing a "zoom" capability for allocating all the scanning resources to a smaller region of interest, allowing high resolution aberration-corrected imaging. In the present system we used a 0 Dpt contact lens to stabilize the mouse eye position and to allow long duration imaging. Defocus (axial focus position) in our system is controlled by the collimation of the OCT sample arm entrance beam.

  17. Field confinement with aberration correction for solid immersion lens based fluorescence correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Rao, Ramachandra; Mitic, Jelena; Serov, Alexandre; Leitgeb, Rainer A.; Lasser, Theo

    2007-03-01

    The solid immersion lens (SIL) as a tool for increasing the field confinement as well as providing optimal performance by aberration compensation in a confocal fluorescence correlation spectroscopy (FCS) system is illustrated here. Using Zernike polynomials we show that aberration compensation and the resultant pre-shaping of the incident wavefront enables near diffraction-limited performance. This is explained based on vectorial computations for high apertures in the Debye approximation. The obtained axial resolution parameters are compared with the obtained diffusion times in a SIL-FCS experiment for measurements in solutions done at the single molecule level.

  18. Smart microscope: an adaptive optics learning system for aberration correction in multiphoton confocal microscopy.

    PubMed

    Albert, O; Sherman, L; Mourou, G; Norris, T B; Vdovin, G

    2000-01-01

    Off-axis aberrations in a beam-scanning multiphoton confocal microscope are corrected with a deformable mirror. The optimal mirror shape for each pixel is determined by a genetic learning algorithm, in which the second-harmonic or two-photon fluorescence signal from a reference sample is maximized. The speed of the convergence is improved by use of a Zernike polynomial basis for the deformable mirror shape. This adaptive optical correction scheme is implemented in an all-reflective system by use of extremely short (10-fs) optical pulses, and it is shown that the scanning area of an f:1 off-axis parabola can be increased by nine times with this technique. PMID:18059779

  19. Effects of higher-order aberration correction on stereopsis at different viewing durations.

    PubMed

    Kang, Jian; Xiao, Fei; Zhao, Junlei; Zhao, Haoxin; Hu, Yiyun; Tang, Guomao; Dai, Yun; Zhang, Yudong

    2015-07-01

    To better understand how the eye's optics affects stereopsis, we measured stereoacuity before and after higher-order aberration (HOA) correction with a binocular adaptive optics visual simulator. The HOAs were corrected either binocularly or monocularly in the better eye (the eye with better contrast sensitivity). A two-line stereo pattern served as the visual stimulus. Stereo thresholds at different viewing durations were obtained with the psychophysical method of constant stimuli. Binocular HOA correction led to significant improvement in stereoacuity. However, better eye HOA correction could bring either a bad degradation or a slight improvement in stereoacuity. As viewing duration increased, the stereo benefit approached the level of 1.0 for both binocular and better eye correction, suggesting that long viewing durations might weaken the effects of the eye's optical quality on stereopsis.

  20. Aberration correction for direct laser written waveguides in a transverse geometry.

    PubMed

    Huang, L; Salter, P S; Payne, F; Booth, M J

    2016-05-16

    The depth dependent spherical aberration is investigated for ultrafast laser written waveguides fabricated in a transverse writing geometry using the slit beam shaping technique in the low pulse repetition rate regime. The axial elongation of the focus caused by the aberration leads to a distortion of the refractive index change, and waveguides designed as single mode become multimode. We theoretically estimate a depth range over which the aberration effects can be compensated simply by adjusting the incident laser power. If deeper fabrication is required, it is demonstrated experimentally that the aberration can be successfully removed using adaptive optics to fabricate single mode optical waveguides over a depth range > 1 mm. PMID:27409879

  1. Simple system of aberration correction for very large spherical primary mirrors

    NASA Astrophysics Data System (ADS)

    Beach, David A.

    2000-10-01

    Several large telescopes are now being proposed that would benefit from the cost reduction due to the use of spherical primary mirror. However, structural cost constraints require compact formats that tend to impose very high speeds, e.g. f/1.5, which renders difficult the correction of the resulting very large spherical aberration. A technique is described here in which a spherical concentric Cassegrain-like primary-secondary combination is followed by a simple catadioptric focal modifier. The spherical primary is 9m diameter, f/1.5, and the final focus is f/5 with a sub-arcsecond resolution over a 5 arcminute angular field for a passband of 480-850nm. Primary- secondary separation is only 11m and central obscuration is only 11% of pupil area. The two relatively small corrector components provide the functions of concentric meniscus and zonal corrector plate and are made from the same single glass- BK7 is the example given, but silica or any other preferred glass is possible. The relatively small zonal corrector is the only aspheric surface in the entire system. A related system is described elsewhere in which a 30 arcminute angular field can be achieved with a similar resolution, but with more complex glass requirements. However, supply of such exotic glasses may be difficult in large diameters, and the system presented here may find a place in some specialized applications.

  2. Atom-column distinction by Kikuchi pattern observed by an aberration-corrected convergent electron probe.

    PubMed

    Saitoh, Koh; Tatara, Yoshihide; Tanaka, Nobuo

    2010-01-01

    Kikuchi patterns of an MgO crystal at the [110] incidence have been taken by a sub-angstrom electron beam focused on the single atom-column. A significant change in intensity has been observed in the 111 band; that is, the contrast in the central and side bands is reversed depending on the illuminated atom-column. The contrast reversal in the 111 band has been reproduced by multislice simulation using the frozen-phonon approach. The beam-position dependence of the 111 band intensity can be interpreted by electron channelling and the reciprocity theorem. The anomalous Kikuchi pattern can be a probe for identifying the illuminated atom-column, which is useful for column-by-column electron energy-loss spectroscopy and X-ray emission spectroscopy.

  3. Device and method for creating Gaussian aberration-corrected electron beams

    DOEpatents

    McMorran, Benjamin; Linck, Martin

    2016-01-19

    Electron beam phase gratings have phase profiles that produce a diffracted beam having a Gaussian or other selected intensity profile. Phase profiles can also be selected to correct or compensate electron lens aberrations. Typically, a low diffraction order produces a suitable phase profile, and other orders are discarded.

  4. Development of a monochromator for aberration-corrected scanning transmission electron microscopy.

    PubMed

    Mukai, Masaki; Okunishi, Eiji; Ashino, Masanori; Omoto, Kazuya; Fukuda, Tomohisa; Ikeda, Akihiro; Somehara, Kazunori; Kaneyama, Toshikatsu; Saitoh, Tomohiro; Hirayama, Tsukasa; Ikuhara, Yuichi

    2015-06-01

    In this article, we report the development of a new 200-kV analytical electron microscope equipped with a monochromator with an integrated double Wien-filter system. It enables us to study the electronic structures of materials in detail using electron energy-loss spectroscopy (EELS) analysis at an atomic scale. A highly monochromated and isotropically round electron probe is produced on the specimen plane. The ultimate energy resolutions with 0.1-s acquisition times are measured to be 36 meV at 200 kV and 30 meV at 60 kV. In an EELS mapping experiment performed on SrTiO3 with a monochromated electron probe whose energy resolution is 146 meV, an elemental map exhibits atomic resolution.

  5. Direct imaging of quantum wires nucleated at diatomic steps

    SciTech Connect

    Molina, S. I.; Varela, M.; Sales, D. L.; Ben, T.; Pizarro, J.; Galindo, P. L.; Fuster, D.; Gonzalez, Y.; Gonzalez, L.; Pennycook, S. J.

    2007-10-01

    Atomic steps at growth surfaces are important heterogeneous sources for nucleation of epitaxial nano-objects. In the presence of misfit strain, we show that the nucleation process takes place preferentially at the upper terrace of the step as a result of the local stress relaxation. Evidence for strain-induced nucleation comes from the direct observation by postgrowth, atomic resolution, Z-contrast imaging of an InAs-rich region in a nanowire located on the upper terrace surface of an interfacial diatomic step.

  6. Analysis of electron beam damage of exfoliated MoS2 sheets and quantitative HAADF-STEM imaging

    PubMed Central

    Garcia, A.; Raya, A.M.; Mariscal, M.M.; Esparza, R.; Herrera, M.; Molina, S.I.; Scavello, G.; Galindo, P.L.; Jose-Yacaman, M.; Ponce, A.

    2014-01-01

    In this work we examined MoS2 sheets by aberration-corrected scanning transmission electron microscopy (STEM) at three different energies: 80, 120 and 200 kV. Structural damage of the MoS2 sheets has been controlled at 80 kV according a theoretical calculation based on the inelastic scattering of the electrons involved in the interaction electron-matter. The threshold energy for the MoS2 material has been found and experimentally verified in the microscope. At energies higher than the energy threshold we show surface and edge defects produced by the electron beam irradiation. Quantitative analysis at atomic level in the images obtained at 80 kV has been performed using the experimental images and via STEM simulations using SICSTEM software to determine the exact number of MoS2 layers. PMID:24929924

  7. Analysis of electron beam damage of exfoliated MoS₂ sheets and quantitative HAADF-STEM imaging.

    PubMed

    Garcia, Alejandra; Raya, Andres M; Mariscal, Marcelo M; Esparza, Rodrigo; Herrera, Miriam; Molina, Sergio I; Scavello, Giovanni; Galindo, Pedro L; Jose-Yacaman, Miguel; Ponce, Arturo

    2014-11-01

    In this work we examined MoS₂ sheets by aberration-corrected scanning transmission electron microscopy (STEM) at three different energies: 80, 120 and 200 kV. Structural damage of the MoS₂ sheets has been controlled at 80 kV according a theoretical calculation based on the inelastic scattering of the electrons involved in the interaction electron-matter. The threshold energy for the MoS₂ material has been found and experimentally verified in the microscope. At energies higher than the energy threshold we show surface and edge defects produced by the electron beam irradiation. Quantitative analysis at atomic level in the images obtained at 80 kV has been performed using the experimental images and via STEM simulations using SICSTEM software to determine the exact number of MoS2₂ layers.

  8. Image

    SciTech Connect

    Marsh, Amber; Harsch, Tim; Pitt, Julie; Firpo, Mike; Lekin, April; Pardes, Elizabeth

    2007-08-31

    The computer side of the IMAGE project consists of a collection of Perl scripts that perform a variety of tasks; scripts are available to insert, update and delete data from the underlying Oracle database, download data from NCBI's Genbank and other sources, and generate data files for download by interested parties. Web scripts make up the tracking interface, and various tools available on the project web-site (image.llnl.gov) that provide a search interface to the database.

  9. Direct imaging of doped fluorine in LaFeAsO1-xFx superconductor by atomic scale spectroscopy

    NASA Astrophysics Data System (ADS)

    Tohei, Tetsuya; Mizoguchi, Teruyasu; Hiramatsu, Hidenori; Kamihara, Yoichi; Hosono, Hideo; Ikuhara, Yuichi

    2009-11-01

    We report direct observation of fluorine ion dopants in the recently discovered LaFeAsO1-xFx superconductor, where the doping is critical for the superconductivity. Employing spectroscopic imaging based on scanning transmission electron microscopy, the spatial distribution of the doped fluorine ions, which are invisible in Z-contrast imaging, is clearly visualized with atomic-scale resolution. The observation directly proves that fluorine substitutes into the oxygen site in the superconducting LaFeAsO1-xFx compound. Our results demonstrate the potential of the present method for revealing dopants undetectable by conventional microscopy imaging.

  10. Wavefront sensorless approaches to adaptive optics for in vivo fluorescence imaging of mouse retina

    NASA Astrophysics Data System (ADS)

    Wahl, Daniel J.; Bonora, Stefano; Mata, Oscar S.; Haunerland, Bengt K.; Zawadzki, Robert J.; Sarunic, Marinko V.; Jian, Yifan

    2016-03-01

    Adaptive optics (AO) is necessary to correct aberrations when imaging the mouse eye with high numerical aperture. In order to obtain cellular resolution, we have implemented wavefront sensorless adaptive optics for in vivo fluorescence imaging of mouse retina. Our approach includes a lens-based system and MEMS deformable mirror for aberration correction. The AO system was constructed with a reflectance channel for structural images and fluorescence channel for functional images. The structural imaging was used in real-time for navigation on the retina using landmarks such as blood vessels. We have also implemented a tunable liquid lens to select the retinal layer of interest at which to perform the optimization. At the desired location on the mouse retina, the optimization algorithm used the fluorescence image data to drive a modal hill-climbing algorithm using an intensity or sharpness image quality metric. The optimization requires ~30 seconds to complete a search up to the 20th Zernike mode. In this report, we have demonstrated the AO performance for high-resolution images of the capillaries in a fluorescence angiography. We have also made progress on an approach to AO with pupil segmentation as a possible sensorless technique suitable for small animal retinal imaging. Pupil segmentation AO was implemented on the same ophthalmic system and imaging performance was demonstrated on fluorescent beads with induced aberrations.

  11. Low cost molded optics for IR imaging

    NASA Astrophysics Data System (ADS)

    Zhao, Jing; DiFilippo, Vincent; Li, Michael

    2009-05-01

    Infrared sensors play a critical role in detection, guidance, and targeting in today's military systems and warfighter equipment, ranging from man-portable to space-borne. Although significant progress is being made in the development of IR imagers, another important component of IR sensors has not evolved significantly-the optics. Current IR lenses are primarily made of expensive single-crystal germanium with tedious mechanical fabrication operations that include grinding, polishing, and edging. There is an industry wide need for lower cost and higher performance IR lenses. Agiltron has developed a technology to directly mold IR lenses to net-shape without additional finishing operations. This manufacturing technology produces optics with many-fold reductions in cost, size, weight, and fabrication time. The ability to reproducibly manufacture aspheric optics with complex net-shapes reduces the number of lenses traditionally required for imaging systems, providing aberration correction as well as system weight and size reductions. Additionally, anti-reflective surfaces can be molded into the glass, eliminating the need for expensive AR coatings. This technology utilizes a new chalcogenide glass material that reduces temperature induced index of refraction changes to near zero, and has a thermal expansion coefficient similar to aluminum. The result is a new generation of low cost, high performance and thermally robust IR lens systems.

  12. Sub-angstrom microscopy through incoherent imaging and image reconstruction

    NASA Astrophysics Data System (ADS)

    Pennycook, S. J.; Jesson, D. E.; Chisholm, M. F.; Ferridge, A. G.; Seddon, M. J.

    1992-03-01

    Z-contrast scanning transmission electron microscopy (STEM) with a high-angle annular detector breaks the coherence of the imaging process, and provides an incoherent image of a crystal projection. Even in the presence of strong dynamical diffraction, the image can be accurately described as a convolution between an object function, sharply peaked at the projected atomic sites, and the probe intensity profile. Such an image can be inverted intuitively without the need for model structures, and therefore provides the important capability to reveal unanticipated interfacial arrangements. It represents a direct image of the crystal projection, revealing the location of the atomic columns and their relative high-angle scattering power. Since no phase is associated with a peak in the object function or the contrast transfer function, extension to higher resolution is also straightforward. Image restoration techniques such as maximum entropy, in conjunction with the 1.3 (Angstrom) probe anticipated for a 300 kV STEM, appear to provide a simple and robust route to the achievement of sub-(Angstrom) resolution electron microscopy.

  13. Experimental quantification of annular dark-field images in scanning transmission electron microscopy.

    PubMed

    Lebeau, James M; Stemmer, Susanne

    2008-11-01

    This paper reports on a method to obtain atomic resolution Z-contrast (high-angle annular dark-field) images with intensities normalized to the incident beam. The procedure bypasses the built-in signal processing hardware of the microscope to obtain the large dynamic range necessary for consecutive measurements of the incident beam and the intensities in the Z-contrast image. The method is also used to characterize the response of the annular dark-field detector output, including conditions that avoid saturation and result in a linear relationship between the electron flux reaching the detector and its output. We also characterize the uniformity of the detector response across its entire area and determine its size and shape, which are needed as input for image simulations. We present normalized intensity images of a SrTiO(3) single crystal as a function of thickness. Averaged, normalized atom column intensities and the background intensity are extracted from these images. The results from the approach developed here can be used for direct, quantitative comparisons with image simulations without any need for scaling. PMID:18707809

  14. Structural Analysis and Direct Imaging of Rotational Stacking Faults in Few-Layer Graphene Synthesized from Solid Botanical Precursor

    NASA Astrophysics Data System (ADS)

    Kalita, Golap; Wakita, Koichi; Umeno, Masayoshi

    2011-07-01

    Here, we report the structural analysis and rotational stacking faults of few-layer graphene sheets derived by the controlled pyrolysis of the solid botanical derivative camphor (C10H16O). The second-order Raman spectra of the sheets show that the graphene layers are more than one single layer, and the numbers of layers can be controlled by adjusting the amount of camphor pyrolyzed. Transmission electron microscopy images show a minimum of 3 layers for thinner graphene sheets and a maximum of 12 layers for thicker graphene sheets. Low-voltage aberration-corrected high-resolution transmission electron microscopy is also carried out to gain insight into the hexagonal structure and stacking of graphene layers. The transmission electron microscopy study showed the presence of moiré patterns with a relative rotation between graphene layers.

  15. Direct imaging of rotating molecules anchored on graphene

    NASA Astrophysics Data System (ADS)

    Choe, Jeongheon; Lee, Yangjin; Fang, Lei; Lee, Gun-Do; Bao, Zhenan; Kim, Kwanpyo

    2016-07-01

    There has been significant research interest in controlling and imaging molecular dynamics, such as translational and rotational motions, especially at a single molecular level. Here we applied aberration-corrected transmission electron microscopy (ACTEM) to actuate and directly image the rotational motions of molecules anchored on a single-layer-graphene sheet. Nanometer-sized carbonaceous molecules anchored on graphene provide ideal systems for monitoring rotational motions via ACTEM. We observed the preferential registry of longer molecular axis along graphene zigzag or armchair lattice directions due to the stacking-dependent molecule-graphene energy landscape. The calculated cross section from elastic scattering theory was used to experimentally estimate the rotational energy barriers of molecules on graphene. The observed energy barrier was within the range of 1.5-12 meV per atom, which is in good agreement with previous calculation results. We also performed molecular dynamics simulations, which revealed that the edge atoms of the molecule form stably bonds to graphene defects and can serve as a pivot point for rotational dynamics. Our study demonstrates the versatility of ACTEM for the investigation of molecular dynamics and configuration-dependent energetics at a single molecular level.There has been significant research interest in controlling and imaging molecular dynamics, such as translational and rotational motions, especially at a single molecular level. Here we applied aberration-corrected transmission electron microscopy (ACTEM) to actuate and directly image the rotational motions of molecules anchored on a single-layer-graphene sheet. Nanometer-sized carbonaceous molecules anchored on graphene provide ideal systems for monitoring rotational motions via ACTEM. We observed the preferential registry of longer molecular axis along graphene zigzag or armchair lattice directions due to the stacking-dependent molecule-graphene energy landscape. The

  16. High resolution multimodal clinical ophthalmic imaging system.

    PubMed

    Mujat, Mircea; Ferguson, R Daniel; Patel, Ankit H; Iftimia, Nicusor; Lue, Niyom; Hammer, Daniel X

    2010-05-24

    We developed a multimodal adaptive optics (AO) retinal imager which is the first to combine high performance AO-corrected scanning laser ophthalmoscopy (SLO) and swept source Fourier domain optical coherence tomography (SSOCT) imaging modes in a single compact clinical prototype platform. Such systems are becoming ever more essential to vision research and are expected to prove their clinical value for diagnosis of retinal diseases, including glaucoma, diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinitis pigmentosa. The SSOCT channel operates at a wavelength of 1 microm for increased penetration and visualization of the choriocapillaris and choroid, sites of major disease activity for DR and wet AMD. This AO system is designed for use in clinical populations; a dual deformable mirror (DM) configuration allows simultaneous low- and high-order aberration correction over a large range of refractions and ocular media quality. The system also includes a wide field (33 deg.) line scanning ophthalmoscope (LSO) for initial screening, target identification, and global orientation, an integrated retinal tracker (RT) to stabilize the SLO, OCT, and LSO imaging fields in the presence of lateral eye motion, and a high-resolution LCD-based fixation target for presentation of visual cues. The system was tested in human subjects without retinal disease for performance optimization and validation. We were able to resolve and quantify cone photoreceptors across the macula to within approximately 0.5 deg (approximately 100-150 microm) of the fovea, image and delineate ten retinal layers, and penetrate to resolve features deep into the choroid. The prototype presented here is the first of a new class of powerful flexible imaging platforms that will provide clinicians and researchers with high-resolution, high performance adaptive optics imaging to help guide therapies, develop new drugs, and improve patient outcomes.

  17. Observations of Co4+ in a higher spin state and the increase in the Seebeck coefficient of thermoelectric Ca3Co4O9.

    PubMed

    Klie, R F; Qiao, Q; Paulauskas, T; Gulec, A; Rebola, A; Öğüt, S; Prange, M P; Idrobo, J C; Pantelides, S T; Kolesnik, S; Dabrowski, B; Ozdemir, M; Boyraz, C; Mazumdar, D; Gupta, A

    2012-05-11

    Ca3Co4O9 has a unique structure that leads to exceptionally high thermoelectric transport. Here we report the achievement of a 27% increase in the room-temperature in-plane Seebeck coefficient of Ca3Co4O9 thin films. We combine aberration-corrected Z-contrast imaging, atomic-column resolved electron energy-loss spectroscopy, and density-functional calculations to show that the increase is caused by stacking faults with Co4+-ions in a higher spin state compared to that of bulk Ca3Co4O9. The higher Seebeck coefficient makes the Ca3Co4O9 system suitable for many high temperature waste-heat-recovery applications.

  18. Observations of Co4+ in a Higher Spin State and the Increase in the Seebeck Coefficient of Thermoelectric Ca3Co4O9

    SciTech Connect

    Klie, Robert F; Qiao, Q.; Paulauskas, T.; Gulec, A.; Rebola, A.; Ogut, Serdar; Prange, Micah P; Idrobo Tapia, Juan C; Pantelides, Sokrates T.; Kolesnik, S.; Dabrowski, B.; Ozdemir, M.; Boyraz, C.; Mazumdar, Dipanjan; Gupta, Dr. Arunava

    2012-01-01

    Ca{sub 3}Co{sub 4}O{sub 9} has a unique structure that leads to exceptionally high thermoelectric transport. Here we report the achievement of a 27% increase in the room-temperature in-plane Seebeck coefficient of Ca{sub 3}Co{sub 4}O{sub 9} thin films. We combine aberration-corrected Z-contrast imaging, atomic-column resolved electron energy-loss spectroscopy, and density-functional calculations to show that the increase is caused by stacking faults with Co4+-ions in a higher spin state compared to that of bulk Ca{sub 3}Co{sub 4}O{sub 9}. The higher Seebeck coefficient makes the Ca{sub 3}Co{sub 4}O{sub 9} system suitable for many high temperature waste-heat-recovery applications.

  19. Influence of total beam current on HRTEM image resolution in differentially pumped ETEM with nitrogen gas.

    PubMed

    Bright, A N; Yoshida, K; Tanaka, N

    2013-01-01

    Environmental transmission electron microscopy (ETEM) enables the study of catalytic and other reaction processes as they occur with Angstrom-level resolution. The microscope used is a dedicated ETEM (Titan ETEM, FEI Company) with a differential pumping vacuum system and apertures, allowing aberration corrected high-resolution transmission electron microscopy (HRTEM) imaging to be performed with gas pressures up to 20 mbar in the sample area and with significant advantages over membrane-type E-cell holders. The effect on image resolution of varying the nitrogen gas pressure, electron beam current density and total beam current were measured using information limit (Young's fringes) on a standard cross grating sample and from silicon crystal lattice imaging. As expected, increasing gas pressure causes a decrease in HRTEM image resolution. However, the total electron beam current also causes big changes in the image resolution (lower beam current giving better resolution), whereas varying the beam current density has almost no effect on resolution, a result that has not been reported previously. This behavior is seen even with zero-loss filtered imaging, which we believe shows that the drop in resolution is caused by elastic scattering at gas ions created by the incident electron beam. Suitable conditions for acquiring high resolution images in a gas environment are discussed. Lattice images at nitrogen pressures up to 16 mbar are shown, with 0.12 nm information transfer at 4 mbar.

  20. Atomic imaging using secondary electrons in a scanning transmission electron microscope: experimental observations and possible mechanisms.

    PubMed

    Inada, H; Su, D; Egerton, R F; Konno, M; Wu, L; Ciston, J; Wall, J; Zhu, Y

    2011-06-01

    We report detailed investigation of high-resolution imaging using secondary electrons (SE) with a sub-nanometer probe in an aberration-corrected transmission electron microscope, Hitachi HD2700C. This instrument also allows us to acquire the corresponding annular dark-field (ADF) images both simultaneously and separately. We demonstrate that atomic SE imaging is achievable for a wide range of elements, from uranium to carbon. Using the ADF images as a reference, we studied the SE image intensity and contrast as functions of applied bias, atomic number, crystal tilt, and thickness to shed light on the origin of the unexpected ultrahigh resolution in SE imaging. We have also demonstrated that the SE signal is sensitive to the terminating species at a crystal surface. A possible mechanism for atomic-scale SE imaging is proposed. The ability to image both the surface and bulk of a sample at atomic-scale is unprecedented, and can have important applications in the field of electron microscopy and materials characterization.

  1. 4D STEM: High efficiency phase contrast imaging using a fast pixelated detector

    NASA Astrophysics Data System (ADS)

    Yang, H.; Jones, L.; Ryll, H.; Simson, M.; Soltau, H.; Kondo, Y.; Sagawa, R.; Banba, H.; MacLaren, I.; Nellist, P. D.

    2015-10-01

    Phase contrast imaging is widely used for imaging beam sensitive and weak phase objects in electron microscopy. In this work we demonstrate the achievement of high efficient phase contrast imaging in STEM using the pnCCD, a fast direct electron pixelated detector, which records the diffraction patterns at every probe position with a speed of 1000 to 4000 frames per second, forming a 4D STEM dataset simultaneously with the incoherent Z-contrast imaging. Ptychographic phase reconstruction has been applied and the obtained complex transmission function reveals the phase of the specimen. The results using GaN and Ti, Nd- doped BiFeO3 show that this imaging mode is especially powerful for imaging light elements in the presence of much heavier elements.

  2. Design of an offset fed scanning antenna for the shuttle imaging microwave system. [performance prediction parabolic reflectors and microwave antennas for space shuttles

    NASA Technical Reports Server (NTRS)

    Gustincic, J. J.

    1975-01-01

    A design study is described for a mechanically scanned offset fed parabolic torus reflector antenna having a 4m x 2m aperture for simultaneous use at eleven frequency channels from UHF to millimeter wavelengths. A design for the antenna is presented utilizing dipole and horn feeds at the low frequencies and a Gregorian aberration correcting subreflector system for feeding the torus at the high frequencies. The results and details of a theroetical study based on geometrical optics performed to evaluate the high frequency design and the results of an experimental study involving a one-tenth scale model for evaluation of the low-frequency behavior are given. Beam efficiencies, antenna patterns, beamwidths and cross polarization levels are presented and these results demonstrate that the antenna concept is viable for the Shuttle Imaging Microwave System requirement.

  3. Wide field-of-view fluorescence image deconvolution with aberration-estimation from Fourier ptychography

    PubMed Central

    Chung, Jaebum; Kim, Jinho; Ou, Xiaoze; Horstmeyer, Roarke; Yang, Changhuei

    2016-01-01

    This paper presents a method to simultaneously acquire an aberration-corrected, wide field-of-view fluorescence image and a high-resolution coherent bright-field image using a computational microscopy method. First, the procedure applies Fourier ptychographic microscopy (FPM) to retrieve the amplitude and phase of a sample, at a resolution that significantly exceeds the cutoff spatial frequency of the microscope objective lens. At the same time, redundancy within the set of acquired FPM bright-field images offers a means to estimate microscope aberrations. Second, the procedure acquires an aberrated fluorescence image, and computationally improves its resolution through deconvolution with the estimated aberration map. An experimental demonstration successfully improves the bright-field resolution of fixed, stained and fluorescently tagged HeLa cells by a factor of 4.9, and reduces the error caused by aberrations in a fluorescence image by up to 31%, over a field of view of 6.2 mm by 9.3 mm. For optimal deconvolution, we show the fluorescence image needs to have a signal-to-noise ratio of at least ~18. PMID:26977345

  4. Wide field-of-view fluorescence image deconvolution with aberration-estimation from Fourier ptychography.

    PubMed

    Chung, Jaebum; Kim, Jinho; Ou, Xiaoze; Horstmeyer, Roarke; Yang, Changhuei

    2016-02-01

    This paper presents a method to simultaneously acquire an aberration-corrected, wide field-of-view fluorescence image and a high-resolution coherent bright-field image using a computational microscopy method. First, the procedure applies Fourier ptychographic microscopy (FPM) to retrieve the amplitude and phase of a sample, at a resolution that significantly exceeds the cutoff spatial frequency of the microscope objective lens. At the same time, redundancy within the set of acquired FPM bright-field images offers a means to estimate microscope aberrations. Second, the procedure acquires an aberrated fluorescence image, and computationally improves its resolution through deconvolution with the estimated aberration map. An experimental demonstration successfully improves the bright-field resolution of fixed, stained and fluorescently tagged HeLa cells by a factor of 4.9, and reduces the error caused by aberrations in a fluorescence image by up to 31%, over a field of view of 6.2 mm by 9.3 mm. For optimal deconvolution, we show the fluorescence image needs to have a signal-to-noise ratio of at least ~18. PMID:26977345

  5. Single myelin fiber imaging in living rodents without labeling by deep optical coherence microscopy

    NASA Astrophysics Data System (ADS)

    Ben Arous, Juliette; Binding, Jonas; Léger, Jean-François; Casado, Mariano; Topilko, Piotr; Gigan, Sylvain; Claude Boccara, A.; Bourdieu, Laurent

    2011-11-01

    Myelin sheath disruption is responsible for multiple neuropathies in the central and peripheral nervous system. Myelin imaging has thus become an important diagnosis tool. However, in vivo imaging has been limited to either low-resolution techniques unable to resolve individual fibers or to low-penetration imaging of single fibers, which cannot provide quantitative information about large volumes of tissue, as required for diagnostic purposes. Here, we perform myelin imaging without labeling and at micron-scale resolution with >300-μm penetration depth on living rodents. This was achieved with a prototype [termed deep optical coherence microscopy (deep-OCM)] of a high-numerical aperture infrared full-field optical coherence microscope, which includes aberration correction for the compensation of refractive index mismatch and high-frame-rate interferometric measurements. We were able to measure the density of individual myelinated fibers in the rat cortex over a large volume of gray matter. In the peripheral nervous system, deep-OCM allows, after minor surgery, in situ imaging of single myelinated fibers over a large fraction of the sciatic nerve. This allows quantitative comparison of normal and Krox20 mutant mice, in which myelination in the peripheral nervous system is impaired. This opens promising perspectives for myelin chronic imaging in demyelinating diseases and for minimally invasive medical diagnosis.

  6. Single myelin fiber imaging in living rodents without labeling by deep optical coherence microscopy.

    PubMed

    Ben Arous, Juliette; Binding, Jonas; Léger, Jean-François; Casado, Mariano; Topilko, Piotr; Gigan, Sylvain; Boccara, A Claude; Bourdieu, Laurent

    2011-11-01

    Myelin sheath disruption is responsible for multiple neuropathies in the central and peripheral nervous system. Myelin imaging has thus become an important diagnosis tool. However, in vivo imaging has been limited to either low-resolution techniques unable to resolve individual fibers or to low-penetration imaging of single fibers, which cannot provide quantitative information about large volumes of tissue, as required for diagnostic purposes. Here, we perform myelin imaging without labeling and at micron-scale resolution with >300-μm penetration depth on living rodents. This was achieved with a prototype [termed deep optical coherence microscopy (deep-OCM)] of a high-numerical aperture infrared full-field optical coherence microscope, which includes aberration correction for the compensation of refractive index mismatch and high-frame-rate interferometric measurements. We were able to measure the density of individual myelinated fibers in the rat cortex over a large volume of gray matter. In the peripheral nervous system, deep-OCM allows, after minor surgery, in situ imaging of single myelinated fibers over a large fraction of the sciatic nerve. This allows quantitative comparison of normal and Krox20 mutant mice, in which myelination in the peripheral nervous system is impaired. This opens promising perspectives for myelin chronic imaging in demyelinating diseases and for minimally invasive medical diagnosis.

  7. Surface determination through atomically resolved secondary-electron imaging

    NASA Astrophysics Data System (ADS)

    Ciston, J.; Brown, H. G.; D'Alfonso, A. J.; Koirala, P.; Ophus, C.; Lin, Y.; Suzuki, Y.; Inada, H.; Zhu, Y.; Allen, L. J.; Marks, L. D.

    2015-06-01

    Unique determination of the atomic structure of technologically relevant surfaces is often limited by both a need for homogeneous crystals and ambiguity of registration between the surface and bulk. Atomically resolved secondary-electron imaging is extremely sensitive to this registration and is compatible with faceted nanomaterials, but has not been previously utilized for surface structure determination. Here we report a detailed experimental atomic-resolution secondary-electron microscopy analysis of the c(6 × 2) reconstruction on strontium titanate (001) coupled with careful simulation of secondary-electron images, density functional theory calculations and surface monolayer-sensitive aberration-corrected plan-view high-resolution transmission electron microscopy. Our work reveals several unexpected findings, including an amended registry of the surface on the bulk and strontium atoms with unusual seven-fold coordination within a typically high surface coverage of square pyramidal TiO5 units. Dielectric screening is found to play a critical role in attenuating secondary-electron generation processes from valence orbitals.

  8. Surface determination through atomically resolved secondary-electron imaging

    DOE PAGES

    Ciston, J.; Brown, H. G.; D’Alfonso, A. J.; Koirala, P.; Ophus, C.; Lin, Y.; Suzuki, Y.; Inada, H.; Zhu, Y.; Allen, L. J.; et al

    2015-06-17

    We report that unique determination of the atomic structure of technologically relevant surfaces is often limited by both a need for homogeneous crystals and ambiguity of registration between the surface and bulk. Atomically resolved secondary-electron imaging is extremely sensitive to this registration and is compatible with faceted nanomaterials, but has not been previously utilized for surface structure determination. Here we show a detailed experimental atomic-resolution secondary-electron microscopy analysis of the c(6 x 2) reconstruction on strontium titanate (001) coupled with careful simulation of secondary-electron images, density functional theory calculations and surface monolayer-sensitive aberration-corrected plan-view high-resolution transmission electron microscopy. Our workmore » reveals several unexpected findings, including an amended registry of the surface on the bulk and strontium atoms with unusual seven-fold coordination within a typically high surface coverage of square pyramidal TiO5 units. Lastly, dielectric screening is found to play a critical role in attenuating secondary-electron generation processes from valence orbitals.« less

  9. Surface determination through atomically resolved secondary-electron imaging

    SciTech Connect

    Ciston, J.; Brown, H. G.; D’Alfonso, A. J.; Koirala, P.; Ophus, C.; Lin, Y.; Suzuki, Y.; Inada, H.; Zhu, Y.; Allen, L. J.; Marks, L. D.

    2015-06-17

    We report that unique determination of the atomic structure of technologically relevant surfaces is often limited by both a need for homogeneous crystals and ambiguity of registration between the surface and bulk. Atomically resolved secondary-electron imaging is extremely sensitive to this registration and is compatible with faceted nanomaterials, but has not been previously utilized for surface structure determination. Here we show a detailed experimental atomic-resolution secondary-electron microscopy analysis of the c(6 x 2) reconstruction on strontium titanate (001) coupled with careful simulation of secondary-electron images, density functional theory calculations and surface monolayer-sensitive aberration-corrected plan-view high-resolution transmission electron microscopy. Our work reveals several unexpected findings, including an amended registry of the surface on the bulk and strontium atoms with unusual seven-fold coordination within a typically high surface coverage of square pyramidal TiO5 units. Lastly, dielectric screening is found to play a critical role in attenuating secondary-electron generation processes from valence orbitals.

  10. Surface determination through atomically resolved secondary-electron imaging

    PubMed Central

    Ciston, J.; Brown, H. G.; D'Alfonso, A. J.; Koirala, P.; Ophus, C.; Lin, Y.; Suzuki, Y.; Inada, H.; Zhu, Y.; Allen, L. J.; Marks, L. D.

    2015-01-01

    Unique determination of the atomic structure of technologically relevant surfaces is often limited by both a need for homogeneous crystals and ambiguity of registration between the surface and bulk. Atomically resolved secondary-electron imaging is extremely sensitive to this registration and is compatible with faceted nanomaterials, but has not been previously utilized for surface structure determination. Here we report a detailed experimental atomic-resolution secondary-electron microscopy analysis of the c(6 × 2) reconstruction on strontium titanate (001) coupled with careful simulation of secondary-electron images, density functional theory calculations and surface monolayer-sensitive aberration-corrected plan-view high-resolution transmission electron microscopy. Our work reveals several unexpected findings, including an amended registry of the surface on the bulk and strontium atoms with unusual seven-fold coordination within a typically high surface coverage of square pyramidal TiO5 units. Dielectric screening is found to play a critical role in attenuating secondary-electron generation processes from valence orbitals. PMID:26082275

  11. Direct imaging of rotating molecules anchored on graphene.

    PubMed

    Choe, Jeongheon; Lee, Yangjin; Fang, Lei; Lee, Gun-Do; Bao, Zhenan; Kim, Kwanpyo

    2016-07-21

    There has been significant research interest in controlling and imaging molecular dynamics, such as translational and rotational motions, especially at a single molecular level. Here we applied aberration-corrected transmission electron microscopy (ACTEM) to actuate and directly image the rotational motions of molecules anchored on a single-layer-graphene sheet. Nanometer-sized carbonaceous molecules anchored on graphene provide ideal systems for monitoring rotational motions via ACTEM. We observed the preferential registry of longer molecular axis along graphene zigzag or armchair lattice directions due to the stacking-dependent molecule-graphene energy landscape. The calculated cross section from elastic scattering theory was used to experimentally estimate the rotational energy barriers of molecules on graphene. The observed energy barrier was within the range of 1.5-12 meV per atom, which is in good agreement with previous calculation results. We also performed molecular dynamics simulations, which revealed that the edge atoms of the molecule form stably bonds to graphene defects and can serve as a pivot point for rotational dynamics. Our study demonstrates the versatility of ACTEM for the investigation of molecular dynamics and configuration-dependent energetics at a single molecular level. PMID:27333828

  12. The effect of zirconium implantation on the structure of sapphire

    SciTech Connect

    Sina, Younes; McHargue, Carl J; Duscher, Gerd; Zhang, Yanwen

    2012-01-01

    The effect of zirconium implantation on the structure of sapphire was investigated by 175 keV Zr implantation at room temperature to a fluence of 4 1016 ions/cm2 into sapphire single crystals. Samples were examined by several experimental techniques: Rutherford backscattering spectroscopy along a channeling direction (RBS-C), electron-energy loss spectroscopy (EELS), and Z-contrast images obtained in an aberration-corrected scanning transmission electron microscope. Range and deposited energy were simulated with SRIM-2008.04. The Z-contrast images from transmission electron microscope indicated: a near surface damaged layer ~30 nm thick, a subsurface region exhibiting "random" de-channeling ~52 nm thick, and a deeper damaged, crystalline zone ~64 nm thick. The RBS-C spectra confirmed the presence of these three regions. The two damaged regions contained high concentrations of as yet unresolved defect clusters. The intermediate region contained Zr-clusters embedded in an "amorphous" matrix that exhibited short-range order corresponding to -Al2O3, i.e., a defective spinel structure. The EELS measurements show that the amorphous region is deficient in oxygen.

  13. The structure of dodecagonal (Ta,V){sub 1.6}Te imaged by phase-contrast scanning transmission electron microscopy

    SciTech Connect

    Krumeich, F.; Mueller, E.; Wepf, R.A.; Conrad, M.; Reich, C.; Harbrecht, B.; Nesper, R.

    2012-10-15

    While HRTEM is the well-established method to characterize the structure of dodecagonal tantalum (vanadium) telluride quasicrystals and their periodic approximants, phase-contrast imaging performed on an aberration-corrected scanning transmission electron microscope (STEM) represents a favorable alternative. The (Ta,V){sub 151}Te{sub 74} clusters, the basic structural unit in all these phases, can be visualized with high resolution. A dependence of the image contrast on defocus and specimen thickness has been observed. In thin areas, the projected crystal potential is basically imaged with either dark or bright contrast at two defocus values close to Scherzer defocus as confirmed by image simulations utilizing the principle of reciprocity. Models for square-triangle tilings describing the arrangement of the basic clusters can be derived from such images. - Graphical abstract: PC-STEM image of a (Ta,V){sub 151}Te{sub 74} cluster. Highlights: Black-Right-Pointing-Pointer C{sub s}-corrected STEM is applied for the characterization of dodecagonal quasicrystals. Black-Right-Pointing-Pointer The projected potential of the structure is mirrored in the images. Black-Right-Pointing-Pointer Phase-contrast STEM imaging depends on defocus and thickness. Black-Right-Pointing-Pointer For simulations of phase-contrast STEM images, the reciprocity theorem is applicable.

  14. Large field-of-view wavefront control for deep brain imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Park, Jung-Hoon; Cui, Meng

    2016-03-01

    The biggest obstacle for deep tissue imaging is the scattering of light due to the heterogeneous distribution of biological tissue. In this respect, multiphoton microscopy has an inherent advantage as the scattering is significantly reduced by the use of longer excitation wavelengths. However, as we go deeper into the brain, effects of scattering still accumulate resulting in a loss of resolution and increased background noise. Adaptive optics is an ideal tool of choice to correct for such distortions of the excitation wavefront; the incident light can be tuned to cancel out the wavefront distortion experienced while propagating into greater depths resulting in a diffraction limited focus at the depth of interest. However, the biggest limitation of adaptive optics for in vivo brain imaging is its limited corrected field-of-view (FOV). For typical multiphoton laser scanning microscopes, the wavefront corrector for adaptive optics is placed at the pupil plane. This means that a single correction wavefront is applied to the entire scanned FOV which results in inefficient correction as the correction is averaged over the entire FOV. In this work, we demonstrate a novel approach to measure and display different correction wavefronts over different segments of the FOV. The application of the different correction wavefronts for each segment is realized in parallel resulting in fast aberration corrected imaging over a large FOV for high resolution in vivo brain imaging.

  15. Pixelated detectors and improved efficiency for magnetic imaging in STEM differential phase contrast.

    PubMed

    Krajnak, Matus; McGrouther, Damien; Maneuski, Dzmitry; Shea, Val O'; McVitie, Stephen

    2016-06-01

    The application of differential phase contrast imaging to the study of polycrystalline magnetic thin films and nanostructures has been hampered by the strong diffraction contrast resulting from the granular structure of the materials. In this paper we demonstrate how a pixelated detector has been used to detect the bright field disk in aberration corrected scanning transmission electron microscopy (STEM) and subsequent processing of the acquired data allows efficient enhancement of the magnetic contrast in the resulting images. Initial results from a charged coupled device (CCD) camera demonstrate the highly efficient nature of this improvement over previous methods. Further hardware development with the use of a direct radiation detector, the Medipix3, also shows the possibilities where the reduction in collection time is more than an order of magnitude compared to the CCD. We show that this allows subpixel measurement of the beam deflection due to the magnetic induction. While the detection and processing is data intensive we have demonstrated highly efficient DPC imaging whereby pixel by pixel interpretation of the induction variation is realised with great potential for nanomagnetic imaging. PMID:27085170

  16. Chemistry and Structure of Graphene Oxide via Direct Imaging.

    PubMed

    Dave, Shreya H; Gong, Chuncheng; Robertson, Alex W; Warner, Jamie H; Grossman, Jeffrey C

    2016-08-23

    Graphene oxide (GO) and reduced GO (rGO) are the only variants of graphene that can be manufactured at the kilogram scale, and yet the widely accepted model for their structure has largely relied on indirect evidence. Notably, existing high-resolution transmission electron microscopy (HRTEM) studies of graphene oxide report long-range order of sp(2) lattice with isolated defect clusters. Here, we present HRTEM evidence of a different structural form of GO, where nanocrystalline regions of sp(2) lattice are surrounded by regions of disorder. The presence of contaminants that adsorb to the surface of the material at room temperature normally prevents direct observation of the intrinsic atomic structure of this defective GO. To overcome this, we use an in situ heating holder within an aberration-corrected TEM (AC-TEM) to study the atomic structure of this nanocrystalline graphene oxide from room temperature to 700 °C. As the temperature increases to above 500 °C, the adsorbates detach from the GO and the underlying atomic structure is imaged to be small 2-4 nm crystalline domains within a polycrystalline GO film. By combining spectroscopic evidence with the AC-TEM data, we support the dynamic interpretation of the structural evolution of graphene oxide.

  17. STEM-EELS imaging of complex oxides and interfaces

    SciTech Connect

    Varela del Arco, Maria; Gazquez Alabart, Jaume; Pennycook, Stephen J

    2012-01-01

    The success of the correction of spherical aberration in the electron microscope has revolutionized our views of oxides. This is a very important class of materials that poses an exciting promise towards future applications of some of the most intriguing phenomena in condensed matter physics: colossal magnetoresistance, colossal ionic conductivity, high Tc superconductivity, ferroelectricity, etc. Understanding the physics underlying such phenomena, especially in low dimensional systems (thin films, interfaces, nanowires, nanoparticles, etc), relies on the availability of techniques capable of looking at these systems in real space and with atomic resolution and even beyond: in many cases the system properties depend on minuscule amounts of minuscule point defects that alter the materials properties dramatically. Atomic resolution spectroscopy in the aberration corrected electron microscope is one of the most powerful techniques available to materials scientists today. This article will briefly review some state-of-the-art applications of these techniques to oxide materials: from atomic resolution elemental mapping and single atom imaging to applications to real systems including oxide interfaces and mapping of physical properties such as the spin state of magnetic atoms.

  18. Few-layer graphene as a support film for transmission electron microscopy imaging of nanoparticles.

    PubMed

    McBride, James R; Lupini, Andrew R; Schreuder, Michael A; Smith, Nathanael J; Pennycook, Stephen J; Rosenthal, Sandra J

    2009-12-01

    One consistent limitation for high-resolution imaging of small nanoparticles is the high background signal from the amorphous carbon support film. With interest growing for smaller and smaller nanostructures, state of the art electron microscopes are becoming necessary for rudimentary tasks, such as nanoparticle sizing. As a monolayer of carbon, free-standing graphene represents the ultimate support film for nanoparticle imaging. In this work, conventional high-resolution transmission electron microscopy (HRTEM) and aberration-corrected scanning transmission electron microscopy (STEM) were used to assess the benefits and feasibility of few-layer graphene support films. Suspensions of few-layer graphene to produce the support films were prepared by simple sonication of exfoliated graphite. The greatest benefit was observed for conventional HRTEM, where lattice resolved imaging of sub 2 nm CdSe nanocrystals was achieved. The few-layer graphene films were also used as a support film for C(s)-corrected STEM and electron energy loss spectroscopy of CuInSe(2) nanocrystals. PMID:20356171

  19. Potential of high-Z contrast agents in clinical contrast-enhanced computed tomography

    SciTech Connect

    Nowak, Tristan; Hupfer, Martin; Brauweiler, Robert; Eisa, Fabian; Kalender, Willi A.

    2011-12-15

    Purpose: Currently, only iodine- and barium-based contrast media (CM) are used in clinical contrast-enhanced computed tomography (CE-CT). High-Z metals would produce a higher contrast at equal mass density for the x-ray spectra used in clinical CT. Using such materials might allow for significant dose reductions in CE-CT. The purpose of this study was to quantify the potential for dose reduction when using CM based on heavy metals. Methods: The contrast-to-noise ratio weighted by dose (CNRD) was determined as a function of scan protocol by means of measurements and simulations on a clinical CT scanner. For simulations, water cylinders with diameters 160, 320, 480, and 640 mm were used to cover a broad range of patient sizes. Measurements were conducted with 160 and 320 mm water-equivalent plastic cylinders. A central bore of 13 mm diameter was present in all phantoms. The tube voltage was varied from 80 to 140 kV for measurements and from 60 to 180 kV for simulations. Additional tin filtration of thicknesses 0.4, 0.8, and 1.2 mm was applied in the simulation to evaluate a range of spectral hardness. The bore was filled with a mixture of water and 10 mg/ml of pure iodine, holmium, gadolinium, ytterbium, osmium, tungsten, gold, and bismuth for the simulations and with aqueous solutions of ytterbium, tungsten, gold, and bismuth salts as well as Iopromid containing 10 mg/ml of the pure materials for the measurements. CNRDs were compared to iodine at phantom size-dependent reference voltages for all high-Z materials and the resulting dose reduction was calculated for equal contrast-to-noise ratio. Results: Dose reduction potentials strongly depended on phantom size, spectral hardness, and tube voltage. Depending on the added filtration, a dose reduction of 19%-60% could be reached at 80 kV with gadolinium for the 160 mm phantom, 52%-69% at 100 kV with holmium for the 320 mm phantom, 62%-78% with 120 kV for hafnium and the 480 mm phantom and 74%-86% with 140 kV for gold and the 640 mm phantom. While gadolinium might be considered at 160 mm diameter, hafnium showed the best overall performance for phantom sizes of 320 mm and above. The measurements conducted on the clinical CT scanner showed very good agreement with simulations with deviations in the order of 5 to 10%. Conclusions: The results of this study encourage the development and use of CM based on high-Z materials, especially for adipose patients, where high tube voltages are necessary to reach sufficiently short scan times. Hafnium proved to be the best compromise for average-size and for adipose patients. Even higher-Z materials such as gold and bismuth showed a good overall performance in conjunction with high tube voltage, large patients or strong added filtration and may be recommended for scans under these conditions.

  20. Focusing aberration corrections for ultrasonic inspections of disk forgings when using a surface compensating mirror and segmented annular phased array

    NASA Astrophysics Data System (ADS)

    Friedl, Jon Hiram, Jr.

    Phased array transducers are playing an increasing role in ultrasonic nondestructive evaluation inspection applications, and one area of their use is in the inspection of critical jet engine components such as titanium alloy turbine disk forgings. Inspection of these forging disks is performed during stages of their manufacturing, particularly at an intermediate stage when the forging disk has a deliberate "sonic shape." A forging's sonic shape, from which the final disk shape will be machined, is conducive to ultrasonic testing inspections due to its simple entry surfaces. These entry surfaces are primarily planar or conical surfaces. In prior work, forgings from General Electric Aircraft Engines, Pratt & Whitney, and Honeywell Engines and Systems were ultrasonically inspected through their planar interfaces, accomplished with a 10 MHz, segmented annular, compound spherical, phased array transducer designed to perform inspections through planar interfaces. Proof-of-concept research used this array along with surface compensating ultrasonic mirrors to inspect through the conical entry surfaces in these forgings. While successful, it was believed that the results of these inspections fell below what would be possible due to non-ideal focusing conditions and other focusing aberrations. To correct for focusing aberrations when inspecting through forging material planar and curved interfaces, three progressively more sophisticated ray-tracing algorithms were developed to generate delay time sets for phasing transducer array elements, including an initial 2D method from prior work, a refined 2D method designed to more accurately account for refraction at interfaces, and a 3D method designed for circumferentially phasing the segmented annular array. Ultrasonic inspections using these methods were performed on two sets of forging material specimens, with either planar or curved interfaces, thicknesses ranging from 0.2 inches to 2.7 inches, and each containing a 1/128-inch-diameter flat bottom hole (#1/2 FBH) reflector. FBH responses from planar interface specimens allowed comparison of the initial and refined 2D inspection methods. The refined 2D inspection method used on the planar and curved interface specimens evaluated the performance of the surface compensating mirror. The refined 2D and 3D inspection methods were compared using the curved interface specimens.

  1. Letter: A method for the chromatic aberration correction of a laser time of-flight mass analyzer.

    PubMed

    Sysoeva, Elizaveta A; Sysoev, Alexander A

    2016-01-01

    The new ion-optical system of the laser time-of-flight (TOF) mass spectrometer on the basis of two tandem wedge-shape reflectors has been offered and implemented. A new method of correcting chromatic aberration by the ion energy was proposed that used a wire electrode unit with adjustable potentials. This unit allows one to adjust the local TOF of the ions in a narrow energy range ± (1-2)% within the total ion packet with an energy spread of ± 20%. The method reduces the duration of the ion packets by up to 1.5ns, which enables us to obtain the restriction of resolution at a level not worse than R ~ 10500 for a TOF ~35 µs. The aim of the project is to increase the separation of isobaric ions to improve the limit of detection of the laser TOF-MS for the analysis of high-purity samples. PMID:27553736

  2. Nanoscale Energy-Filtered Scanning Confocal Electron Microscopy Using a Double-Aberration-Corrected Transmission Electron Microscope

    SciTech Connect

    Wang Peng; Behan, Gavin; Kirkland, Angus I.; Nellist, Peter D.; Takeguchi, Masaki; Hashimoto, Ayako; Mitsuishi, Kazutaka; Shimojo, Masayuki

    2010-05-21

    We demonstrate that a transmission electron microscope fitted with two spherical-aberration correctors can be operated as an energy-filtered scanning confocal electron microscope. A method for establishing this mode is described and initial results showing 3D chemical mapping with nanoscale sensitivity to height and thickness changes in a carbon film are presented. Importantly, uncorrected chromatic aberration does not limit the depth resolution of this technique and moreover performs an energy-filtering role, which is explained in terms of a combined depth and energy-loss response function.

  3. Modelling of AlAs/GaAs interfacial structures using high-angle annular dark field (HAADF) image simulations.

    PubMed

    Robb, Paul D; Finnie, Michael; Craven, Alan J

    2012-07-01

    High angle annular dark field (HAADF) image simulations were performed on a series of AlAs/GaAs interfacial models using the frozen-phonon multislice method. Three general types of models were considered-perfect, vicinal/sawtooth and diffusion. These were chosen to demonstrate how HAADF image measurements are influenced by different interfacial structures in the technologically important III-V semiconductor system. For each model, interfacial sharpness was calculated as a function of depth and compared to aberration-corrected HAADF experiments of two types of AlAs/GaAs interfaces. The results show that the sharpness measured from HAADF imaging changes in a complicated manner with thickness for complex interfacial structures. For vicinal structures, it was revealed that the type of material that the probe projects through first of all has a significant effect on the measured sharpness. An increase in the vicinal angle was also shown to generate a wider interface in the random step model. The Moison diffusion model produced an increase in the interface width with depth which closely matched the experimental results of the AlAs-on-GaAs interface. In contrast, the interface width decreased as a function of depth in the linear diffusion model. Only in the case of the perfect model was it possible to ascertain the underlying structure directly from HAADF image analysis.

  4. Characterization of conductive nanobiomaterials derived from viral assemblies by low-voltage STEM imaging and Raman scattering

    NASA Astrophysics Data System (ADS)

    Plascencia-Villa, Germán; Carreño-Fuentes, Liliana; Bahena, Daniel; José-Yacamán, Miguel; Palomares, Laura A.; Ramírez, Octavio T.

    2014-09-01

    New technologies require the development of novel nanomaterials that need to be fully characterized to achieve their potential. High-resolution low-voltage scanning transmission electron microscopy (STEM) has proven to be a very powerful technique in nanotechnology, but its use for the characterization of nanobiomaterials has been limited. Rotavirus VP6 self-assembles into nanotubular assemblies that possess an intrinsic affinity for Au ions. This property was exploited to produce hybrid nanobiomaterials by the in situ functionalization of recombinant VP6 nanotubes with gold nanoparticles. In this work, Raman spectroscopy and advanced analytical electron microscopy imaging with spherical aberration-corrected (Cs) STEM and nanodiffraction at low-voltage doses were employed to characterize nanobiomaterials. STEM imaging revealed the precise structure and arrangement of the protein templates, as well as the nanostructure and atomic arrangement of gold nanoparticles with high spatial sub-Angstrom resolution and avoided radiation damage. The imaging was coupled with backscattered electron imaging, ultra-high resolution scanning electron microscopy and x-ray spectroscopy. The hybrid nanobiomaterials that were obtained showed unique properties as bioelectronic conductive devices and showed enhanced Raman scattering by their precise arrangement into superlattices, displaying the utility of viral assemblies as functional integrative self-assembled nanomaterials for novel applications.

  5. Retinal image quality with the different types of intraocular lenses including new idea of the hybrid IOLs

    NASA Astrophysics Data System (ADS)

    Siedlecki, D.; Zając, M.; Nowak, J.

    2007-07-01

    Cataract is one of the most frequent reasons of blindness all around the world. Its treatment relies on removing the pathologically altered crystalline lens and replacing it with an artificial intraocular lens (IOL). There exists plenty of types of such implants, which differ in the optical materials and designs (shapes). However one of the important features, which is rather overlooked in the development of the intraocular implants is the chromatic aberration and its influence on the retinal image quality. In this study authors try to estimate the influence of the design and optical material of the implant on the retinal image quality in the polychromatic light, taking into consideration several exemplary types of IOLs which are commercially available. Authors also propose the partially achromatized hybrid IOLs, the longitudinal chromatic aberration (LCA)of which reduces the total LCA of the phakic eye to the level of a healthy eye's LCA. Several image characteristics, as the polychromatic Point Spread Function (PSF) and the Modulation Transfer Function (MTF) and the polychromatic encircled energy are estimated. The results of the simulations show the significance of the partial chromatic aberration correction.

  6. High resolution transmission electron microscope Imaging and first-principles simulations of atomic-scale features in graphene membrane

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Bhandari, Sagar; Yi, Wei; Bell, David; Westervelt, Robert; Kaxiras, Efthimios

    2012-02-01

    Ultra-thin membranes such as graphene[1] are of great importance for basic science and technology applications. Graphene sets the ultimate limit of thinness, demonstrating that a free-standing single atomic layer not only exists but can be extremely stable and strong [2--4]. However, both theory [5, 6] and experiments [3, 7] suggest that the existence of graphene relies on intrinsic ripples that suppress the long-wavelength thermal fluctuations which otherwise spontaneously destroy long range order in a two dimensional system. Here we show direct imaging of the atomic features in graphene including the ripples resolved using monochromatic aberration-corrected transmission electron microscopy (TEM). We compare the images observed in TEM with simulated images based on an accurate first-principles total potential. We show that these atomic scale features can be mapped through accurate first-principles simulations into high resolution TEM contrast. [1] Geim, A. K. & Novoselov, K. S. Nat. Mater. 6, 183-191, (2007). [2] Novoselov, K. S.et al. Science 306, 666-669, (2004). [3] Meyer, J. C. et al. Nature 446, 60-63, (2007). [4] Lee, C., Wei, X. D., Kysar, J. W. & Hone, J. Science 321, 385-388, (2008). [5] Nelson, D. R. & Peliti, L. J Phys-Paris 48, 1085-1092, (1987). [6] Fasolino, A., Los, J. H. & Katsnelson, M. I. Nat. Mater. 6, 858-861, (2007). [7] Meyer, J. C. et al. Solid State Commun. 143, 101-109, (2007).

  7. Multimodal adaptive optics for depth-enhanced high-resolution ophthalmic imaging

    NASA Astrophysics Data System (ADS)

    Hammer, Daniel X.; Mujat, Mircea; Iftimia, Nicusor V.; Lue, Niyom; Ferguson, R. Daniel

    2010-02-01

    We developed a multimodal adaptive optics (AO) retinal imager for diagnosis of retinal diseases, including glaucoma, diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinitis pigmentosa (RP). The development represents the first ever high performance AO system constructed that combines AO-corrected scanning laser ophthalmoscopy (SLO) and swept source Fourier domain optical coherence tomography (SSOCT) imaging modes in a single compact clinical prototype platform. The SSOCT channel operates at a wavelength of 1 μm for increased penetration and visualization of the choriocapillaris and choroid, sites of major disease activity for DR and wet AMD. The system is designed to operate on a broad clinical population with a dual deformable mirror (DM) configuration that allows simultaneous low- and high-order aberration correction. The system also includes a wide field line scanning ophthalmoscope (LSO) for initial screening, target identification, and global orientation; an integrated retinal tracker (RT) to stabilize the SLO, OCT, and LSO imaging fields in the presence of rotational eye motion; and a high-resolution LCD-based fixation target for presentation to the subject of stimuli and other visual cues. The system was tested in a limited number of human subjects without retinal disease for performance optimization and validation. The system was able to resolve and quantify cone photoreceptors across the macula to within ~0.5 deg (~100-150 μm) of the fovea, image and delineate ten retinal layers, and penetrate to resolve targets deep into the choroid. In addition to instrument hardware development, analysis algorithms were developed for efficient information extraction from clinical imaging sessions, with functionality including automated image registration, photoreceptor counting, strip and montage stitching, and segmentation. The system provides clinicians and researchers with high-resolution, high performance adaptive optics imaging to help

  8. IMAGES, IMAGES, IMAGES

    SciTech Connect

    Marcus, A.

    1980-07-01

    The role of images of information (charts, diagrams, maps, and symbols) for effective presentation of facts and concepts is expanding dramatically because of advances in computer graphics technology, increasingly hetero-lingual, hetero-cultural world target populations of information providers, the urgent need to convey more efficiently vast amounts of information, the broadening population of (non-expert) computer users, the decrease of available time for reading texts and for decision making, and the general level of literacy. A coalition of visual performance experts, human engineering specialists, computer scientists, and graphic designers/artists is required to resolve human factors aspects of images of information. The need for, nature of, and benefits of interdisciplinary effort are discussed. The results of an interdisciplinary collaboration are demonstrated in a product for visualizing complex information about global energy interdependence. An invited panel will respond to the presentation.

  9. New image fusion method applied in two-wavelength detection of biochip spots

    NASA Astrophysics Data System (ADS)

    Chang, Rang-Seng; Sheu, Jin-Yi; Lin, Ching-Huang

    2001-09-01

    In the biological systems genetic information is read, stored, modified, transcribed and translated using the rule of molecular recognition. Every nucleic acid strand carries the capacity to recognize complementary sequences through base paring. Molecular biologists commonly use the DNA probes with known sequence to identify the unknown sequence through hybridization. There are many different detection methods for the hybridization results on a genechip. Fluorescent detection is a conventional method. The data analysis based on the fluorescent images and database establishment is necessary for treatment of such a large-amount obtained from a genechip. The unknown sequence has labeled with fluorescent material. Since the excitation and emission band is not a theoretical narrow band. There is a different in emission windows for different microscope. Therefore the data reading is different for different microscope. We combine two narrow band emission data and take it as two wavelengths from one fluorescence. Which by corresponding UV light excitation after we read the fluorescent intensity distribution of two microscope wavelengths for same hybridization DNA sequence spot, we will use image fusion technology to get best resultsDWe introduce a contrast and aberration correction image fusion method by using discrete wavelet transform to two wavelengths identification microarray biochip. This method includes two parts. First, the multiresolution analysis of the two input images are obtained by the discrete wavelet transform, from the ratio of high frequencies to the low frequency on the corresponding spatial resolution level, the directive contrast can be estimated by selecting the suitable subband signals of each input image. The fused image is reconstructed using the inverse wavelet transform.

  10. Influence of spatial and temporal coherences on atomic resolution high angle annular dark field imaging.

    PubMed

    Beyer, Andreas; Belz, Jürgen; Knaub, Nikolai; Jandieri, Kakhaber; Volz, Kerstin

    2016-10-01

    Aberration-corrected (scanning) transmission electron microscopy ((S)TEM) has become a widely used technique when information on the chemical composition is sought on an atomic scale. To extract the desired information, complementary simulations of the scattering process are inevitable. Often the partial spatial and temporal coherences are neglected in the simulations, although they can have a huge influence on the high resolution images. With the example of binary gallium phosphide (GaP) we elucidate the influence of the source size and shape as well as the chromatic aberration on the high angle annular dark field (HAADF) intensity. We achieve a very good quantitative agreement between the frozen phonon simulation and experiment for different sample thicknesses when a Lorentzian source distribution is assumed and the effect of the chromatic aberration is considered. Additionally the influence of amorphous layers introduced by the preparation of the TEM samples is discussed. Taking into account these parameters, the intensity in the whole unit cell of GaP, i.e. at the positions of the different atomic columns and in the region between them, is described correctly. With the knowledge of the decisive parameters, the determination of the chemical composition of more complex, multinary materials becomes feasible.

  11. Influence of spatial and temporal coherences on atomic resolution high angle annular dark field imaging.

    PubMed

    Beyer, Andreas; Belz, Jürgen; Knaub, Nikolai; Jandieri, Kakhaber; Volz, Kerstin

    2016-10-01

    Aberration-corrected (scanning) transmission electron microscopy ((S)TEM) has become a widely used technique when information on the chemical composition is sought on an atomic scale. To extract the desired information, complementary simulations of the scattering process are inevitable. Often the partial spatial and temporal coherences are neglected in the simulations, although they can have a huge influence on the high resolution images. With the example of binary gallium phosphide (GaP) we elucidate the influence of the source size and shape as well as the chromatic aberration on the high angle annular dark field (HAADF) intensity. We achieve a very good quantitative agreement between the frozen phonon simulation and experiment for different sample thicknesses when a Lorentzian source distribution is assumed and the effect of the chromatic aberration is considered. Additionally the influence of amorphous layers introduced by the preparation of the TEM samples is discussed. Taking into account these parameters, the intensity in the whole unit cell of GaP, i.e. at the positions of the different atomic columns and in the region between them, is described correctly. With the knowledge of the decisive parameters, the determination of the chemical composition of more complex, multinary materials becomes feasible. PMID:27391526

  12. Direct imaging of Pt single atoms adsorbed on TiO2 (110) surfaces.

    PubMed

    Chang, Teng-Yuan; Tanaka, Yusuke; Ishikawa, Ryo; Toyoura, Kazuaki; Matsunaga, Katsuyuki; Ikuhara, Yuichi; Shibata, Naoya

    2014-01-01

    Noble metal nanoparticles (e.g., gold and platinum) supported on TiO2 surfaces are utilized in many technological applications such as heterogeneous catalysts. To fully understand their enhanced catalytic activity, it is essential to unravel the interfacial interaction between the metal atoms and TiO2 surfaces at the level of atomic dimensions. However, it has been extremely difficult to directly characterize the atomic-scale structures that result when individual metal atoms are adsorbed on the TiO2 surfaces. Here, we show direct atomic-resolution images of individual Pt atoms adsorbed on TiO2 (110) surfaces using aberration-corrected scanning transmission electron microscopy. Subangstrom spatial resolution enables us to identify five different Pt atom adsorption sites on the TiO2 (110) surface. Combining this with systematic density functional theory calculations reveals that the most favorable Pt adsorption sites are on vacancy sites of basal oxygen atoms that are located in subsurface positions relative to the top surface bridging oxygen atoms.

  13. Atomic scale imaging of competing polar states in a Ruddlesden–Popper layered oxide

    PubMed Central

    Stone, Greg; Ophus, Colin; Birol, Turan; Ciston, Jim; Lee, Che-Hui; Wang, Ke; Fennie, Craig J.; Schlom, Darrell G.; Alem, Nasim; Gopalan, Venkatraman

    2016-01-01

    Layered complex oxides offer an unusually rich materials platform for emergent phenomena through many built-in design knobs such as varied topologies, chemical ordering schemes and geometric tuning of the structure. A multitude of polar phases are predicted to compete in Ruddlesden–Popper (RP), An+1BnO3n+1, thin films by tuning layer dimension (n) and strain; however, direct atomic-scale evidence for such competing states is currently absent. Using aberration-corrected scanning transmission electron microscopy with sub-Ångstrom resolution in Srn+1TinO3n+1 thin films, we demonstrate the coexistence of antiferroelectric, ferroelectric and new ordered and low-symmetry phases. We also directly image the atomic rumpling of the rock salt layer, a critical feature in RP structures that is responsible for the competing phases; exceptional quantitative agreement between electron microscopy and density functional theory is demonstrated. The study shows that layered topologies can enable multifunctionality through highly competitive phases exhibiting diverse phenomena in a single structure. PMID:27578622

  14. Atomic scale imaging of competing polar states in a Ruddlesden-Popper layered oxide.

    PubMed

    Stone, Greg; Ophus, Colin; Birol, Turan; Ciston, Jim; Lee, Che-Hui; Wang, Ke; Fennie, Craig J; Schlom, Darrell G; Alem, Nasim; Gopalan, Venkatraman

    2016-08-31

    Layered complex oxides offer an unusually rich materials platform for emergent phenomena through many built-in design knobs such as varied topologies, chemical ordering schemes and geometric tuning of the structure. A multitude of polar phases are predicted to compete in Ruddlesden-Popper (RP), An+1BnO3n+1, thin films by tuning layer dimension (n) and strain; however, direct atomic-scale evidence for such competing states is currently absent. Using aberration-corrected scanning transmission electron microscopy with sub-Ångstrom resolution in Srn+1TinO3n+1 thin films, we demonstrate the coexistence of antiferroelectric, ferroelectric and new ordered and low-symmetry phases. We also directly image the atomic rumpling of the rock salt layer, a critical feature in RP structures that is responsible for the competing phases; exceptional quantitative agreement between electron microscopy and density functional theory is demonstrated. The study shows that layered topologies can enable multifunctionality through highly competitive phases exhibiting diverse phenomena in a single structure.

  15. Atomic scale imaging of competing polar states in a Ruddlesden-Popper layered oxide

    NASA Astrophysics Data System (ADS)

    Stone, Greg; Ophus, Colin; Birol, Turan; Ciston, Jim; Lee, Che-Hui; Wang, Ke; Fennie, Craig J.; Schlom, Darrell G.; Alem, Nasim; Gopalan, Venkatraman

    2016-08-01

    Layered complex oxides offer an unusually rich materials platform for emergent phenomena through many built-in design knobs such as varied topologies, chemical ordering schemes and geometric tuning of the structure. A multitude of polar phases are predicted to compete in Ruddlesden-Popper (RP), An+1BnO3n+1, thin films by tuning layer dimension (n) and strain; however, direct atomic-scale evidence for such competing states is currently absent. Using aberration-corrected scanning transmission electron microscopy with sub-Ångstrom resolution in Srn+1TinO3n+1 thin films, we demonstrate the coexistence of antiferroelectric, ferroelectric and new ordered and low-symmetry phases. We also directly image the atomic rumpling of the rock salt layer, a critical feature in RP structures that is responsible for the competing phases; exceptional quantitative agreement between electron microscopy and density functional theory is demonstrated. The study shows that layered topologies can enable multifunctionality through highly competitive phases exhibiting diverse phenomena in a single structure.

  16. Study of shuttle imaging microwave system antenna. Volume 1: Conceptual design

    NASA Technical Reports Server (NTRS)

    Wesley, R. W.; Waineo, D. K.; Barton, C. R.; Love, A. W.

    1975-01-01

    A detailed preliminary design and complete performance evaluation are presented of an 11-channel large aperture scanning radiometer antenna for the shuttle imaging microwave system (SIMS) program. Provisions for interfacing the antenna with the space shuttle orbiter are presented and discussed. A program plan for hardware development and a rough order of magnitude (ROM) cost are also included. The conceptual design of the antenna is presented. It consists of a four-meter diameter parabolic torus main reflector, which is a graphite/epoxy shell supported by a graphite/epoxy truss. A rotating feed wheel assembly supports six Gregorian subreflectors covering the upper eight frequency channels from 6.6 GHz through 118.7 GHz, and two three-channel prime forms feed assemblies for 0.6, 1.4, and 2.7 GHz. The feed wheel assembly also holds the radiometers and power supplies, and a drive system using a 400 Hz synchronous motor is described. The RF analysis of the antenna is performed using physical optics procedures for both the dual reflector Gregorian concept and the single reflector prime focus concept. A unique aberration correcting feed for 2.7 GHz is analyzed. A structural analysis is also included. The analyses indicate that the antenna will meet system requirements.

  17. Atomic scale imaging of competing polar states in a Ruddlesden-Popper layered oxide.

    PubMed

    Stone, Greg; Ophus, Colin; Birol, Turan; Ciston, Jim; Lee, Che-Hui; Wang, Ke; Fennie, Craig J; Schlom, Darrell G; Alem, Nasim; Gopalan, Venkatraman

    2016-01-01

    Layered complex oxides offer an unusually rich materials platform for emergent phenomena through many built-in design knobs such as varied topologies, chemical ordering schemes and geometric tuning of the structure. A multitude of polar phases are predicted to compete in Ruddlesden-Popper (RP), An+1BnO3n+1, thin films by tuning layer dimension (n) and strain; however, direct atomic-scale evidence for such competing states is currently absent. Using aberration-corrected scanning transmission electron microscopy with sub-Ångstrom resolution in Srn+1TinO3n+1 thin films, we demonstrate the coexistence of antiferroelectric, ferroelectric and new ordered and low-symmetry phases. We also directly image the atomic rumpling of the rock salt layer, a critical feature in RP structures that is responsible for the competing phases; exceptional quantitative agreement between electron microscopy and density functional theory is demonstrated. The study shows that layered topologies can enable multifunctionality through highly competitive phases exhibiting diverse phenomena in a single structure. PMID:27578622

  18. Effect of scanning beam size on the lateral resolution of mouse retinal imaging with SLO

    PubMed Central

    Zhang, Pengfei; Goswami, Mayank; Zam, Azhar; Pugh, Edward N.; Zawadzki, Robert J.

    2016-01-01

    Scanning laser ophthalmoscopy (SLO) employs the eye’s optics as a microscope objective for retinal imaging in vivo. The mouse retina has become an increasingly important object for investigation of ocular disease and physiology with optogenetic probes. SLO imaging of the mouse eye, in principle, can achieve submicron lateral resolution thanks to a numerical aperture (NA) of ~0.5, about 2.5 times larger than that of the human eye. In the absence of adaptive optics, however, natural ocular aberrations limit the available optical resolution. The use of a contact lens, in principle, can correct many aberrations, permitting the use of a wider scanning beam and, thus, achieving greater resolution then would otherwise be possible. In this Letter, using an SLO equipped with a rigid contact lens, we report the effect of scanning beam size on the lateral resolution of mouse retinal imaging. Theory predicts that the maximum beam size full width at half-maximum (FWHM) that can be used without any deteriorating effects of aberrations is ~0.6 mm. However, increasing the beam size up to the diameter of the dilated pupil is predicted to improve lateral resolution, though not to the diffraction limit. To test these predictions, the dendrites of a retinal ganglion cell expressing YFP were imaged, and transverse scans were analyzed to quantify the SLO system resolution. The results confirmed that lateral resolution increases with the beam size as predicted. With a 1.3 mm scanning beam and no high-order aberration correction, the lateral resolution is ~1.15 μm, superior to that achievable by most human AO-SLO systems. Advantages of this approach include stabilization of the mouse eye and simplified optical design. PMID:26670523

  19. Effect of scanning beam size on the lateral resolution of mouse retinal imaging with SLO.

    PubMed

    Zhang, Pengfei; Goswami, Mayank; Zam, Azhar; Pugh, Edward N; Zawadzki, Robert J

    2015-12-15

    Scanning laser ophthalmoscopy (SLO) employs the eye's optics as a microscope objective for retinal imaging in vivo. The mouse retina has become an increasingly important object for investigation of ocular disease and physiology with optogenetic probes. SLO imaging of the mouse eye, in principle, can achieve submicron lateral resolution thanks to a numerical aperture (NA) of ∼0.5, about 2.5 times larger than that of the human eye. In the absence of adaptive optics, however, natural ocular aberrations limit the available optical resolution. The use of a contact lens, in principle, can correct many aberrations, permitting the use of a wider scanning beam and, thus, achieving greater resolution then would otherwise be possible. In this Letter, using an SLO equipped with a rigid contact lens, we report the effect of scanning beam size on the lateral resolution of mouse retinal imaging. Theory predicts that the maximum beam size full width at half-maximum (FWHM) that can be used without any deteriorating effects of aberrations is ∼0.6  mm. However, increasing the beam size up to the diameter of the dilated pupil is predicted to improve lateral resolution, though not to the diffraction limit. To test these predictions, the dendrites of a retinal ganglion cell expressing YFP were imaged, and transverse scans were analyzed to quantify the SLO system resolution. The results confirmed that lateral resolution increases with the beam size as predicted. With a 1.3 mm scanning beam and no high-order aberration correction, the lateral resolution is ∼1.15  μm, superior to that achievable by most human AO-SLO systems. Advantages of this approach include stabilization of the mouse eye and simplified optical design.

  20. Quantitative Statistical Analysis of Atomic Scale Structural and Chemical Variations in Complex Oxides Interfaces

    NASA Astrophysics Data System (ADS)

    Yang, Hao

    Grain boundaries (GBs) are known to have far-reaching effects on the electrical and mechanical properties of materials. Understanding the atomic scale mechanisms behind these effects requires an accurate determination of the interplay between GB structure and composition. Based on the analysis of a range of grain boundaries using aberration corrected scanning transmission electron microscopy (STEM), a general structural units model has been derived for the structure of grain boundaries in various dense packing cubic materials including FCC metals, perovskites and fluorites. The similarities in the observed grain boundary structures of these materials originate from related space (and point) group symmetries of the parent structures. The presence of structural variations away from the general structural units model may be caused by frustrations of certain symmetry operations that result from the incorporation of point defects (vacancies and impurities). A clear understanding of the similarity and variation in grain boundary atomic structures will not only provide a means to infer the structure-property relationships in broad classes of materials, but also enables us eventually to effectively manipulate the GB structures to achieve better materials properties. To understand these chemical induced variations, and further quantify exactly how atomic scale variations at the boundary plane extend to the practical mesoscale operating length of the system, statistical analysis has been applied to the aberration corrected STEM Z-contrast images acquired from a series of undoped and doped SrTiO3 GBs. In order to understand the effects of oxygen vacancies incorporation, in-situ characterization of GB atomic structures were performed using the Environmental TEM under the reduced gas and heating environment. This analysis of GB similarity and variation provides insights into the structure-composition relationship in GBs to understand the influence of nonstoichiometry and dopant

  1. Quantitative annular dark-field STEM images of a silicon crystal using a large-angle convergent electron probe with a 300-kV cold field-emission gun.

    PubMed

    Kim, Suhyun; Oshima, Yoshifumi; Sawada, Hidetaka; Kaneyama, Toshikatsu; Kondo, Yukihito; Takeguchi, Masaki; Nakayama, Yoshiko; Tanishiro, Yasumasa; Takayanagi, Kunio

    2011-01-01

    Annular dark-field scanning transmission electron microscope (ADF-STEM) images of an Si (001) crystal were obtained by using an aberration-corrected electron microscope, at 30-mrad convergent probe and cold field-emission gun at 300 kV. The intensity of ADF-STEM images, that is, the number of scattered electrons relative to the incident electrons, obtained for specimen thickness from 10 to 50 nm was compared quantitatively with  absorptive multi-slice simulation. The column and background intensities were analyzed by column-by-column two-dimensional Gaussian fitting. These intensities were found to increase linearly with the sample thicknesses. However, the simulated image gave higher column intensity and lower background intensity for all the sample thickness. We found that experimental images were reproduced by the simulation with Gaussian convolution of 70 pm full-width at half-maximum for all the sample thicknesses from 10 to 50 nm. The possible factors accounted for this Gaussian convolution is discussed.

  2. Imaging the Structure of Grains, Grain Boundaries, and Stacking Sequences in Single and Multi-Layer Graphene

    NASA Astrophysics Data System (ADS)

    Muller, David

    2012-02-01

    Graphene can be produced by chemical vapor deposition (CVD) on copper substrates on up to meter scales [1, 2], making their polycrystallinity [3,4] almost unavoidable. By combining aberration-corrected scanning transmission electron microscopy and dark-field transmission electron microscopy, we image graphene grains and grain boundaries across six orders of magnitude. Atomic-resolution images of graphene grain boundaries reveal that different grains can stitch together via pentagon-heptagon pairs. We use diffraction-filtered electron imaging to map the shape and orientation of several hundred grains and boundaries over fields of view of a hundred microns. Single, double and multilayer graphene can be differentiated, and the stacking sequence and relative abundance of sequences can be directly imaged. These images reveal an intricate patchwork of grains with structural details depending strongly on growth conditions. The imaging techniques enabled studies of the structure, properties, and control of graphene grains and grain boundaries [5]. [4pt] [1] X. Li et al., Science 324, 1312 (2009).[0pt] [2] S. Bae et al., Nature Nanotechnol. 5, 574 (2010).[0pt] [3] J. M. Wofford, et al., Nano Lett., (2010).[0pt] [4] P. Y. Huang, et al., Nature 469, 389--392 (2011); arXiv:1009.4714, (2010)[0pt] [5] In collaboration with Pinshane Y. Huang, C. S. Ruiz-Vargas, A. M. van der Zande, A. W. Tsen, L. Brown, R. Hovden, F. Ghahari, W. S. Whitney, M.P. Levendorf, J. W. Kevek, S. Garg, J. S. Alden, C. J. Hustedt, Y. Zhu, N. Petrone, J. Hone, J. Park, P. L. McEuen

  3. Imaging individual lanthanum atoms in zeolite Y by scanning transmission electron microscopy: evidence of lanthanum pair sites

    SciTech Connect

    Xu, Pinghong; Lu, Jing; Aydin, C.; Debefve, Louise M.; Browning, Nigel D.; Chen, Cong-Yan; Gates, Bruce C.

    2015-09-01

    Images of La-exchanged NaY zeolite obtained with aberration-corrected scanning transmission electron microscopy (STEM) show that about 80% of the La cations were present as site-isolated species, with the remainder in pair sites. The distance between La cations in the pair sites ranged from 1.44 to 3.84 Å, consistent with the presence of pairs of cations tilted at various angles with respect to the support surface. The actual distance between La cations in the pair sites is inferred to be approximately 3.84 Å, which is shorter than the distance between the nearest Al sites in the zeolite (4.31 Å). The results therefore suggest the presence of dimeric structures of La cations bridged with OH groups, and the presence of such species has been inferred previously on the basis of X-ray photoelectron spectroscopy (W. Grünert, U. Sauerlandt, R. Schlögl, H.G. Karge, J. Phys. Chem., 97 (1993) 1413).

  4. Lattice parameters from direct-space images at two tilts.

    PubMed

    Qin, W; Fraundorf, P

    2003-04-01

    Lattices in three dimensions are oft studied from the "reciprocal space" perspective of diffraction. Today, the full lattice of a crystal can often be inferred from direct-space information about three sets of non-parallel lattice planes. Such data can come from electron-phase (or less easily Z contrast images) taken at two tilts, provided that one image shows two non-parallel lattice periodicities, and the other shows a periodicity not coplanar with the first two. We outline here protocols for measuring the 3D parameters of cubic lattice types in this way. For randomly oriented nano-crystals with cell side greater than twice the continuous transfer limit, orthogonal +/-15 degrees and +/-10 degrees tilt ranges might allow one to measure 3D parameters of all such lattice types in a specimen from only two well-chosen images. The strategy is illustrated by measuring the lattice parameters of a 10nm WC(1-x) crystal in a plasma-enhanced chemical-vapor deposited thin film.

  5. Measurement of indium concentration profiles and segregation efficiencies from high-angle annular dark field-scanning transmission electron microscopy images.

    PubMed

    Mehrtens, Thorsten; Müller, Knut; Schowalter, Marco; Hu, Dongzhi; Schaadt, Daniel M; Rosenauer, Andreas

    2013-08-01

    We investigated segregation of indium in an InxGa1-xAs/GaAs heterostructure via high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), where contrast strongly depends on the nuclear charges of the scattering atoms (Z-contrast). Indium concentration maps have been deduced from HAADF-STEM images by comparing normalized measured intensities with multislice simulations in the frozen lattice approach. Segregation coefficients were derived following the segregation model of Muraki et al.. This is demonstrated for HAADF-STEM images recorded in [100] and [110] zone-axes. Determined indium concentrations and segregation coefficients are compared with results from composition analysis by lattice fringe analysis (CELFA) measurements and energy-dispersive X-ray analysis (EDX).

  6. Atomic scale dynamics of a solid state chemical reaction directly determined by annular dark-field electron microscopy.

    PubMed

    Pennycook, Timothy J; Jones, Lewys; Pettersson, Henrik; Coelho, João; Canavan, Megan; Mendoza-Sanchez, Beatriz; Nicolosi, Valeria; Nellist, Peter D

    2014-12-22

    Dynamic processes, such as solid-state chemical reactions and phase changes, are ubiquitous in materials science, and developing a capability to observe the mechanisms of such processes on the atomic scale can offer new insights across a wide range of materials systems. Aberration correction in scanning transmission electron microscopy (STEM) has enabled atomic resolution imaging at significantly reduced beam energies and electron doses. It has also made possible the quantitative determination of the composition and occupancy of atomic columns using the atomic number (Z)-contrast annular dark-field (ADF) imaging available in STEM. Here we combine these benefits to record the motions and quantitative changes in the occupancy of individual atomic columns during a solid-state chemical reaction in manganese oxides. These oxides are of great interest for energy-storage applications such as for electrode materials in pseudocapacitors. We employ rapid scanning in STEM to both drive and directly observe the atomic scale dynamics behind the transformation of Mn3O4 into MnO. The results demonstrate we now have the experimental capability to understand the complex atomic mechanisms involved in phase changes and solid state chemical reactions.

  7. Increased bismuth concentration in MBE GaAs{sub 1−x}Bi{sub x} films by oscillating III/V flux ratio during growth

    SciTech Connect

    Wood, Adam W. Babcock, Susan E.; Li, Jincheng; Brown, April S.

    2015-05-15

    The authors have examined bismuth concentration profiles in GaAs{sub 1−x}Bi{sub x} films grown by molecular beam epitaxy using high angle annular dark field imaging (Z-contrast imaging) in an aberration-corrected scanning transmission electron microscope in conjunction with x-ray diffraction. Samples were grown with a gradient in each of the component fluxes, and therefore, the III/V ratio across the substrate. Rotating the sample during growth exposed the growth surface to an oscillating III/V flux ratio. Sinusoidal [Bi] profiles resulted in the growth direction, the wavelength and number of which were consistent with the growth rate and the rate of substrate rotation. However, the magnitude of [Bi] in the observed fluctuations was greater than the maximum [Bi] achieved using the same Bi flux and Ga/As flux ratios in steady-state conditions on a stationary substrate, suggesting that varying the III/V flux ratio during growth promotes the incorporation of Bi in GaAs{sub 1−x}Bi{sub x} films. A proposed qualitative model for how this enhancement might occur hypothesizes a critical role for alternating growth and shrinkage of Ga-Bi predroplet clusters on the surface as the growing material is rotated through Ga-rich and As-rich flux compositions.

  8. Preferential sites for InAsP/InP quantum wire nucleation using molecular dynamics

    NASA Astrophysics Data System (ADS)

    Nuñez-Moraleda, Bernardo; Pizarro, Joaquin; Guerrero, Elisa; Guerrero-Lebrero, Maria P.; Yáñez, Andres; Molina, Sergio Ignacio; Galindo, Pedro Luis

    2014-11-01

    In this paper, stress fields at the surface of the capping layer of self-assembled InAsP quantum wires grown on an InP (001) substrate have been determined from atomistic models using molecular dynamics and Stillinger-Weber potentials. To carry out these calculations, the quantum wire compositional distribution was extracted from previous works, where the As and P distributions were determined by electron energy loss spectroscopy and high-resolution aberration-corrected Z-contrast imaging. Preferential sites for the nucleation of wires on the surface of the capping layer were studied and compared with (i) previous simulations using finite element analysis to solve anisotropic elastic theory equations and (ii) experimentally measured locations of stacked wires. Preferential nucleation sites of stacked wires were determined by the maximum stress location at the MD model surface in good agreement with experimental results and those derived from finite element analysis. This indicates that MD simulations based on empirical potentials provide a suitable and flexible tool to study strain dependent atom processes.

  9. Low kV Atomic Resolution and First Principles Study of the Structure and Bonding at SrTiO3/GaAs Hetero-interfaces

    NASA Astrophysics Data System (ADS)

    Qiao, Qiao; Klie, Robert; Ogut, Serdar

    2012-02-01

    Ultrathin transition-meal oxide films on polar substrates have attracted increasing attention in recent years, due to the emergence of novel interfacial phases, not seen in the bulk of either material. In this study, we have combined aberration-corrected atomic-resolution Z-contrast imaging, electron energy loss spectroscopy (EELS) with first-principles density functional theory calculations to examined the atomic and electronic structures of epitaxially grown, ultrathin SrTiO3 (100) films on GaAs (001). We find that the interface is atomically abrupt and no surface reconstruction of the GaAs (001) surface is observed. Using atomic-column resolved EELS, we show that Ti diffuses into the first few monolayers of GaAs and we will present evidence for the formation of As-oxides at the interface depending on the thin film growth conditions. First-principles DFT calculations will be used to analyze the formation energies of Ti-related impurity defects in the bulk and surface regions of GaAs, as well as the stability of any surface reconstruction at the SrTiO3/GaAs interface. These findings are used to explain transport behavior of the SrTiO3 films as a function of deposition conditions.

  10. New crystal structures in hexagonal CuInS2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Shen, Xiao; Hernández-Pagan, Emil A.; Zhou, Wu; Puzyrev, Yevgeniy S.; Idrobo, Juan C.; MacDonald, Janet E.; Pennycook, Stephen J.; Pantelides, Sokrates T.

    2013-03-01

    CuInS2 is one of the best candidate materials for solar energy harvesting. Its nanocrystals with a hexagonal lattice structure that is different from the bulk chalcopyrite phase have been synthesized by many groups. The structure of these CuInS2 nanocrystals has been previously identified as the wurtzite structure in which the copper and indium atoms randomly occupy the cation sites. Using first-principles total energy and electronic structure calculations based on density functional theory, UV-vis absorption spectroscopy, X-ray diffraction, and atomic resolution Z-contrast images obtained in an aberration-corrected scanning transmission electron microscope, we show that CuInS2 nanocrystals do not form random wurtzite structure. Instead, the CuInS2 nanocrystals consist of several wurtzite- related crystal structures with ordered cation sublattices, some of which are reported for the first time here. This work is supported by the NSF TN-SCORE (JEM), by NSF (WZ), by ORNL's Shared Research Equipment User Program (JCI) sponsored by DOE BES, by DOE BES Materials Sciences and Engineering Division (SJP, STP), and used resources of the National Energy Research Scientific Computing Center, supported by the DOE Office of Science under Contract No. DE-AC02-05CH11231.

  11. Application of a new high-speed magnetic deformable mirror for in-vivo retinal imaging

    NASA Astrophysics Data System (ADS)

    Balderas-Mata, Sandra E.; Jones, Steven M.; Zawadzki, Robert J.; Werner, John S.

    2011-08-01

    Nowadays in ophthalmologic practice several commercial instruments are available to image patient retinas in vivo. Many modern fundus cameras and confocal scanning laser ophthalmoscopes allow acquisition of two dimensional en face images of the retina with both back reflected as well as fluorescent light. Additionally, optical coherence tomography systems allow non-invasive probing of three-dimensional retinal morphology. For all of these instruments the available lateral resolution is limited by optical quality of the human eye used as the imaging objective. To improve lateral resolution and achieve diffraction-limited imaging, adaptive optics (AO) can be implemented with any of these imaging systems to correct both static and dynamic aberrations inherent in human eyes. Most of the wavefront correctors used previously in AO systems have limited dynamic range and an insufficient number of actuators to achieve diffraction-limited correction of most human eyes. Thus, additional corrections were necessary, either by trial lenses or additional deformable mirrors (DMs). The UC Davis AO flood-illuminated fundus camera system described in this paper has been previously used to acquire in vivo images of the photoreceptor mosaic and for psychophysical studies on normal and diseased retinas. These results were acquired using a DM manufactured by Litton ITEK (DM109), which has 109 actuators arranged in a hexagonal array below a continuous front-surface mirror. It has an approximate surface actuator stroke of +/-2μm. Here we present results with a new hi-speed magnetic DM manufactured by ALPAO (DM97, voice coil technology), which has 97 actuators and similar inter-actuator stroke (>3μm, mirror surface) but much higher low-order aberration correction (defocus stroke of at least +/-30μm) than the previous one. In this paper we report results of testing performance of the ALPAO DM for the correction of human eye aberrations. Additionally changes made to our AO flood

  12. Concept for image-guided vitreo-retinal fs-laser surgery: adaptive optics and optical coherence tomography for laser beam shaping and positioning

    NASA Astrophysics Data System (ADS)

    Matthias, Ben; Brockmann, Dorothee; Hansen, Anja; Horke, Konstanze; Knoop, Gesche; Gewohn, Timo; Zabic, Miroslav; Krüger, Alexander; Ripken, Tammo

    2015-03-01

    Fs-lasers are well established in ophthalmic surgery as high precision tools for corneal flap cutting during laser in situ keratomileusis (LASIK) and increasingly utilized for cutting the crystalline lens, e.g. in assisting cataract surgery. For addressing eye structures beyond the cornea, an intraoperative depth resolved imaging is crucial to the safety and success of the surgical procedure due to interindividual anatomical disparities. Extending the field of application even deeper to the posterior eye segment, individual eye aberrations cannot be neglected anymore and surgery with fs-laser is impaired by focus degradation. Our demonstrated concept for image-guided vitreo-retinal fs-laser surgery combines adaptive optics (AO) for spatial beam shaping and optical coherence tomography (OCT) for focus positioning guidance. The laboratory setup comprises an adaptive optics assisted 800 nm fs-laser system and is extended by a Fourier domain optical coherence tomography system. Phantom structures are targeted, which mimic tractional epiretinal membranes in front of excised porcine retina within an eye model. AO and OCT are set up to share the same scanning and focusing optics. A Hartmann-Shack sensor is employed for aberration measurement and a deformable mirror for aberration correction. By means of adaptive optics the threshold energy for laser induced optical breakdown is lowered and cutting precision is increased. 3D OCT imaging of typical ocular tissue structures is achieved with sufficient resolution and the images can be used for orientation of the fs-laser beam. We present targeted dissection of the phantom structures and its evaluation regarding retinal damage.

  13. Atomic-Scale Chemical Imaging of Composition and Bonding at Perovskite Oxide Interfaces

    NASA Astrophysics Data System (ADS)

    Fitting Kourkoutis, L.

    2010-03-01

    Scanning transmission electron microscopy (STEM) in combination with electron energy loss spectroscopy (EELS) has proven to be a powerful technique to study buried perovskite oxide heterointerfaces. With the recent addition of 3^rd order and now 5^th order aberration correction, which provides a factor of 100x increase in signal over an uncorrected system, we are now able to record 2D maps of composition and bonding of oxide interfaces at atomic resolution [1]. Here, we present studies of the microscopic structure of oxide/oxide multilayers and heterostructures by STEM in combination with EELS and its effect on the properties of the film. Using atomic-resolution spectroscopic imaging we show that the degradation of the magnetic and transport properties of La0.7Sr0.3MnO3/SrTiO3 multilayers correlates with atomic intermixing at the interfaces and the presence of extended defects in the La0.7Sr0.3MnO3 layers. When these defects are eliminated, metallic ferromagnetism at room temperature can be stabilized in 5 unit cell thick manganite layers, almost 40% thinner than the previously reported critical thickness of 3-5 nm for sustaining metallic ferromagnetism below Tc in La0.7Sr0.3MnO3 thin films grown on SrTiO3.[4pt] [1] D.A. Muller, L. Fitting Kourkoutis, M. Murfitt, J.H. Song, H.Y. Hwang, J. Silcox, N. Dellby, O.L. Krivanek, Science 319, 1073-1076 (2008).

  14. Lowered threshold energy for femtosecond laser induced optical breakdown in a water based eye model by aberration correction with adaptive optics.

    PubMed

    Hansen, Anja; Géneaux, Romain; Günther, Axel; Krüger, Alexander; Ripken, Tammo

    2013-06-01

    In femtosecond laser ophthalmic surgery tissue dissection is achieved by photodisruption based on laser induced optical breakdown. In order to minimize collateral damage to the eye laser surgery systems should be optimized towards the lowest possible energy threshold for photodisruption. However, optical aberrations of the eye and the laser system distort the irradiance distribution from an ideal profile which causes a rise in breakdown threshold energy even if great care is taken to minimize the aberrations of the system during design and alignment. In this study we used a water chamber with an achromatic focusing lens and a scattering sample as eye model and determined breakdown threshold in single pulse plasma transmission loss measurements. Due to aberrations, the precise lower limit for breakdown threshold irradiance in water is still unknown. Here we show that the threshold energy can be substantially reduced when using adaptive optics to improve the irradiance distribution by spatial beam shaping. We found that for initial aberrations with a root-mean-square wave front error of only one third of the wavelength the threshold energy can still be reduced by a factor of three if the aberrations are corrected to the diffraction limit by adaptive optics. The transmitted pulse energy is reduced by 17% at twice the threshold. Furthermore, the gas bubble motions after breakdown for pulse trains at 5 kilohertz repetition rate show a more transverse direction in the corrected case compared to the more spherical distribution without correction. Our results demonstrate how both applied and transmitted pulse energy could be reduced during ophthalmic surgery when correcting for aberrations. As a consequence, the risk of retinal damage by transmitted energy and the extent of collateral damage to the focal volume could be minimized accordingly when using adaptive optics in fs-laser surgery.

  15. Lowered threshold energy for femtosecond laser induced optical breakdown in a water based eye model by aberration correction with adaptive optics.

    PubMed

    Hansen, Anja; Géneaux, Romain; Günther, Axel; Krüger, Alexander; Ripken, Tammo

    2013-06-01

    In femtosecond laser ophthalmic surgery tissue dissection is achieved by photodisruption based on laser induced optical breakdown. In order to minimize collateral damage to the eye laser surgery systems should be optimized towards the lowest possible energy threshold for photodisruption. However, optical aberrations of the eye and the laser system distort the irradiance distribution from an ideal profile which causes a rise in breakdown threshold energy even if great care is taken to minimize the aberrations of the system during design and alignment. In this study we used a water chamber with an achromatic focusing lens and a scattering sample as eye model and determined breakdown threshold in single pulse plasma transmission loss measurements. Due to aberrations, the precise lower limit for breakdown threshold irradiance in water is still unknown. Here we show that the threshold energy can be substantially reduced when using adaptive optics to improve the irradiance distribution by spatial beam shaping. We found that for initial aberrations with a root-mean-square wave front error of only one third of the wavelength the threshold energy can still be reduced by a factor of three if the aberrations are corrected to the diffraction limit by adaptive optics. The transmitted pulse energy is reduced by 17% at twice the threshold. Furthermore, the gas bubble motions after breakdown for pulse trains at 5 kilohertz repetition rate show a more transverse direction in the corrected case compared to the more spherical distribution without correction. Our results demonstrate how both applied and transmitted pulse energy could be reduced during ophthalmic surgery when correcting for aberrations. As a consequence, the risk of retinal damage by transmitted energy and the extent of collateral damage to the focal volume could be minimized accordingly when using adaptive optics in fs-laser surgery. PMID:23761849

  16. Lowered threshold energy for femtosecond laser induced optical breakdown in a water based eye model by aberration correction with adaptive optics

    PubMed Central

    Hansen, Anja; Géneaux, Romain; Günther, Axel; Krüger, Alexander; Ripken, Tammo

    2013-01-01

    In femtosecond laser ophthalmic surgery tissue dissection is achieved by photodisruption based on laser induced optical breakdown. In order to minimize collateral damage to the eye laser surgery systems should be optimized towards the lowest possible energy threshold for photodisruption. However, optical aberrations of the eye and the laser system distort the irradiance distribution from an ideal profile which causes a rise in breakdown threshold energy even if great care is taken to minimize the aberrations of the system during design and alignment. In this study we used a water chamber with an achromatic focusing lens and a scattering sample as eye model and determined breakdown threshold in single pulse plasma transmission loss measurements. Due to aberrations, the precise lower limit for breakdown threshold irradiance in water is still unknown. Here we show that the threshold energy can be substantially reduced when using adaptive optics to improve the irradiance distribution by spatial beam shaping. We found that for initial aberrations with a root-mean-square wave front error of only one third of the wavelength the threshold energy can still be reduced by a factor of three if the aberrations are corrected to the diffraction limit by adaptive optics. The transmitted pulse energy is reduced by 17% at twice the threshold. Furthermore, the gas bubble motions after breakdown for pulse trains at 5 kilohertz repetition rate show a more transverse direction in the corrected case compared to the more spherical distribution without correction. Our results demonstrate how both applied and transmitted pulse energy could be reduced during ophthalmic surgery when correcting for aberrations. As a consequence, the risk of retinal damage by transmitted energy and the extent of collateral damage to the focal volume could be minimized accordingly when using adaptive optics in fs-laser surgery. PMID:23761849

  17. High resolution X-ray fluorescence imaging for a microbeam radiation therapy treatment planning system

    NASA Astrophysics Data System (ADS)

    Chtcheprov, Pavel; Inscoe, Christina; Burk, Laurel; Ger, Rachel; Yuan, Hong; Lu, Jianping; Chang, Sha; Zhou, Otto

    2014-03-01

    Microbeam radiation therapy (MRT) uses an array of high-dose, narrow (~100 μm) beams separated by a fraction of a millimeter to treat various radio-resistant, deep-seated tumors. MRT has been shown to spare normal tissue up to 1000 Gy of entrance dose while still being highly tumoricidal. Current methods of tumor localization for our MRT treatments require MRI and X-ray imaging with subject motion and image registration that contribute to the measurement error. The purpose of this study is to develop a novel form of imaging to quickly and accurately assist in high resolution target positioning for MRT treatments using X-ray fluorescence (XRF). The key to this method is using the microbeam to both treat and image. High Z contrast media is injected into the phantom or blood pool of the subject prior to imaging. Using a collimated spectrum analyzer, the region of interest is scanned through the MRT beam and the fluorescence signal is recorded for each slice. The signal can be processed to show vascular differences in the tissue and isolate tumor regions. Using the radiation therapy source as the imaging source, repositioning and registration errors are eliminated. A phantom study showed that a spatial resolution of a fraction of microbeam width can be achieved by precision translation of the mouse stage. Preliminary results from an animal study showed accurate iodine profusion, confirmed by CT. The proposed image guidance method, using XRF to locate and ablate tumors, can be used as a fast and accurate MRT treatment planning system.

  18. Image Calibration

    NASA Technical Reports Server (NTRS)

    Peay, Christopher S.; Palacios, David M.

    2011-01-01

    Calibrate_Image calibrates images obtained from focal plane arrays so that the output image more accurately represents the observed scene. The function takes as input a degraded image along with a flat field image and a dark frame image produced by the focal plane array and outputs a corrected image. The three most prominent sources of image degradation are corrected for: dark current accumulation, gain non-uniformity across the focal plane array, and hot and/or dead pixels in the array. In the corrected output image the dark current is subtracted, the gain variation is equalized, and values for hot and dead pixels are estimated, using bicubic interpolation techniques.

  19. Indexing Images.

    ERIC Educational Resources Information Center

    Rasmussen, Edie M.

    1997-01-01

    Focuses on access to digital image collections by means of manual and automatic indexing. Contains six sections: (1) Studies of Image Systems and their Use; (2) Approaches to Indexing Images; (3) Image Attributes; (4) Concept-Based Indexing; (5) Content-Based Indexing; and (6) Browsing in Image Retrieval. Contains 105 references. (AEF)

  20. Identifying unknown nanocrystals by fringe fingerprinting in two dimensions and free-access crystallographic databases

    NASA Astrophysics Data System (ADS)

    Moeck, Peter; Čertik, Ondřej; Seipel, Bjoern; Groebner, Rebecca; Noice, Lori; Upreti, Girish; Fraundorf, Philip; Erni, Rolf; Browning, Nigel D.; Kiesow, Andreas; Jolivet, Jean-Pierre

    2005-11-01

    New needs to determine the crystallography of nanocrystals arise with the advent of science and engineering on the nanometer scale. Direct space high-resolution phase-contrast transmission electron microscopy (HRTEM) and atomic resolution Z-contrast scanning TEM (Z-STEM), when combined with tools for image-based nanocrystallography possess the capacity to meet these needs. This paper introduces such a tool, i.e. fringe fingerprinting in two dimensions (2D), for the identification of unknown nanocrystal phases and compares this method briefly to qualitative standard powder X-ray diffractometry (i.e. spatial frequency fingerprinting). Free-access crystallographic databases are also discussed because the whole fingerprinting concept is only viable if there are comprehensive databases to support the identification of an unknown nanocrystal phase. This discussion provides the rationale for our ongoing development of a dedicated free-access Nano-Crystallography Database (NCD) that contains comprehensive information on both nanocrystal structures and morphologies. The current status of the NCD project and plans for its future developments are briefly outlined. Although feasible in contemporary HRTEMs and Z-STEMs, fringe fingerprinting in 2D (and image-based nanocrystallography in general) will become much more viable with the increased availability of aberration-corrected transmission electron microscopes. When the image acquisition and interpretation are, in addition, automated in such microscopes, fringe fingerprinting in 2D will be able to compete with powder X-ray diffraction for the identification of unknown nanocrystal phases on a routine basis. Since it possesses a range of advantages over powder X-ray diffractometry, e.g., fringe fingerprint plots contain much more information for the identification of an unknown crystal phase, fringe fingerprinting in 2D may then capture a significant part of the nanocrystal metrology market.

  1. Aerosol/Radiation, VNIR/NIR/TIR Imaging, Net Solar and Longwave Radiation, Meteorological Fluxes, Atmospheric Dropsonde, and Ocean Temperature/Salinity Microbuoy Payloads for Earth Observations Using a Manta Unmanned Aerial System (UAS)

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Gao, R. S.; Murphy, D. M.; Telg, H.; Brown, S.; Dhakai, T.; Zappa, C. J.; Stalin, S.

    2014-12-01

    Several new payloads have been developed for use in the Manta UAS. The NOAA/PMEL aerosol payload (Atmos. Meas. Tech., 6, 2115-2120, 2013) has been expanded to include a printed optical particle spectrometer to obtain aerosol size distributions and an upward looking radiometer to measure radiant flux densities through aerosol layers. Lamont-Doherty Earth Observatory (LDEO) has improved its visible and infrared imaging payload to provide precise measurements of ice/snow/ocean surface temperatures accurate to 0.1°C. LDEO has also developed a number of new payloads that include: i) hyperspectral aberration-corrected imaging spectrometers to measure VNIR (400-1000 nm) and NIR (900-1700 nm) spectral radiance of the upper-ocean and sea ice to determine ocean color, ice-age distributions and ice-surface type; ii) up- and downward-looking hemispheric pyrgeometers and pyranometers to measure the net longwave and net shortwave radiation for ice-ocean albedo studies with an onboard visible camera to determine the sea ice fraction and whitecapping; iii) meteorological measurements of turbulent momentum, sensible, and latent fluxes as well as wave height, ice freeboard, and surface roughness with a LIDAR; iv) four dropsonde-microbuoys (DMB) that can be deployed from the Manta. The four DMB measure temperature, pressure, and relative humidity as they descend through the atmosphere. Once they land on the ocean's surface, they deploy a string of sensors that measures temperature and salinity of the upper three meters of the ocean. The ocean sensors telemeter data back to the UAS on subsequent flights. The DMB can also be dropped on an ice flow to measure the rate of the ice movement. Details of these payloads and example data will be reported.

  2. Photothermal imaging

    NASA Astrophysics Data System (ADS)

    Lapotko, Dmitry; Antonishina, Elena

    1995-02-01

    An automated image analysis system with two imaging regimes is described. Photothermal (PT) effect is used for imaging of a temperature field or absorption structure of the sample (the cell) with high sensitivity and spatial resolution. In a cell study PT-technique enables imaging of live non-stained cells, and the monitoring of the cell shape/structure. The system includes a dual laser illumination unit coupled to a conventional optical microscope. A sample chamber provides automated or manual loading of up to 3 samples and cell positioning. For image detection a 256 X 256 10-bit CCD-camera is used. The lasers, scanning stage, and camera are controlled by PC. The system provides optical (transmitted light) image, probe laser optical image, and PT-image acquisition. Operation rate is 1 - 1.5 sec per cell for a cycle: cell positioning -- 3 images acquisition -- image parameters calculation. A special database provides image/parameters storage, presentation, and cell diagnostic according to quantitative image parameters. The described system has been tested during live and stained blood cell studies. PT-images of the cells have been used for cell differentiation. In experiments with the red blood cells (RBC) that originate from normal and anaemia blood parameters for disease differentiation have been found. For white blood cells in PT-images the details of cell structure have found that absent in their optical images.

  3. An inexpensive approach for bright-field and dark-field imaging by scanning transmission electron microscopy in scanning electron microscopy.

    PubMed

    Patel, Binay; Watanabe, Masashi

    2014-02-01

    Scanning transmission electron microscopy in scanning electron microscopy (STEM-in-SEM) is a convenient technique for soft materials characterization. Various specimen-holder geometries and detector arrangements have been used for bright-field (BF) STEM-in-SEM imaging. In this study, to further the characterization potential of STEM-IN-SEM, a new specimen holder has been developed to facilitate direct detection of BF signals and indirect detection of dark-field (DF) signals without the need for substantial instrument modification. DF imaging is conducted with the use of a gold (Au)-coated copper (Cu) plate attached to the specimen holder which directs highly scattered transmitted electrons to an off-axis yttrium-aluminum-garnet (YAG) detector. A hole in the copper plate allows for BF imaging with a transmission electron (TE) detector. The inclusion of an Au-coated Cu plate enhanced DF signal intensity. Experiments validating the acquisition of true DF signals revealed that atomic number (Z) contrast may be achieved for materials with large lattice spacing. However, materials with small lattice spacing still exhibit diffraction contrast effects in this approach. The calculated theoretical fine probe size is 1.8 nm. At 30 kV, in this indirect approach, DF spatial resolution is limited to 3.2 nm as confirmed experimentally. PMID:24423133

  4. An inexpensive approach for bright-field and dark-field imaging by scanning transmission electron microscopy in scanning electron microscopy.

    PubMed

    Patel, Binay; Watanabe, Masashi

    2014-02-01

    Scanning transmission electron microscopy in scanning electron microscopy (STEM-in-SEM) is a convenient technique for soft materials characterization. Various specimen-holder geometries and detector arrangements have been used for bright-field (BF) STEM-in-SEM imaging. In this study, to further the characterization potential of STEM-IN-SEM, a new specimen holder has been developed to facilitate direct detection of BF signals and indirect detection of dark-field (DF) signals without the need for substantial instrument modification. DF imaging is conducted with the use of a gold (Au)-coated copper (Cu) plate attached to the specimen holder which directs highly scattered transmitted electrons to an off-axis yttrium-aluminum-garnet (YAG) detector. A hole in the copper plate allows for BF imaging with a transmission electron (TE) detector. The inclusion of an Au-coated Cu plate enhanced DF signal intensity. Experiments validating the acquisition of true DF signals revealed that atomic number (Z) contrast may be achieved for materials with large lattice spacing. However, materials with small lattice spacing still exhibit diffraction contrast effects in this approach. The calculated theoretical fine probe size is 1.8 nm. At 30 kV, in this indirect approach, DF spatial resolution is limited to 3.2 nm as confirmed experimentally.

  5. Direct imaging of copper catalyst migration inside helical carbon nanofibers.

    PubMed

    Dong, Lifeng; Yu, Liyan; Cui, Zuolin; Dong, Hongzhou; Ercius, Peter; Song, Chengyu; Duden, Thomas

    2012-01-27

    By using a double-aberration-corrected (scanning) transmission electron microscope (STEM/TEM) at an acceleration voltage of only 80 kV, we demonstrate that, due to the low solubility of copper (Cu) in carbon and its affinity with oxygen (O), single-crystal Cu catalysts dissociate into small cuprous oxide (Cu2O) nanoparticles after the growth of carbon nanofibers, and Cu2O nanoparticles ultimately localize on the fiber surfaces. This new finding is a step toward a better understanding of the interactions between Cu catalysts and carbon nanomaterials and could suggest a simple and effective method for eliminating Cu impurities from the fibers. PMID:22172975

  6. Medical Imaging.

    ERIC Educational Resources Information Center

    Barker, M. C. J.

    1996-01-01

    Discusses four main types of medical imaging (x-ray, radionuclide, ultrasound, and magnetic resonance) and considers their relative merits. Describes important recent and possible future developments in image processing. (Author/MKR)

  7. Proof Image

    ERIC Educational Resources Information Center

    Kidron, Ivy; Dreyfus, Tommy

    2014-01-01

    The emergence of a proof image is often an important stage in a learner's construction of a proof. In this paper, we introduce, characterize, and exemplify the notion of proof image. We also investigate how proof images emerge. Our approach starts from the learner's efforts to construct a justification without (or before) attempting any…

  8. Image alignment

    SciTech Connect

    Dowell, Larry Jonathan

    2014-04-22

    Disclosed is a method and device for aligning at least two digital images. An embodiment may use frequency-domain transforms of small tiles created from each image to identify substantially similar, "distinguishing" features within each of the images, and then align the images together based on the location of the distinguishing features. To accomplish this, an embodiment may create equal sized tile sub-images for each image. A "key" for each tile may be created by performing a frequency-domain transform calculation on each tile. A information-distance difference between each possible pair of tiles on each image may be calculated to identify distinguishing features. From analysis of the information-distance differences of the pairs of tiles, a subset of tiles with high discrimination metrics in relation to other tiles may be located for each image. The subset of distinguishing tiles for each image may then be compared to locate tiles with substantially similar keys and/or information-distance metrics to other tiles of other images. Once similar tiles are located for each image, the images may be aligned in relation to the identified similar tiles.

  9. Intracranial imaging.

    PubMed Central

    Gibson, M.; Cook, G.; Al-Kutoubi, A.

    1996-01-01

    This article concentrates on the imaging of intracranial structures and outlines some basic imaging strategies for common clinical presentations. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 PMID:8935596

  10. Optimization-based wavefront sensorless adaptive optics for multiphoton microscopy.

    PubMed

    Antonello, Jacopo; van Werkhoven, Tim; Verhaegen, Michel; Truong, Hoa H; Keller, Christoph U; Gerritsen, Hans C

    2014-06-01

    Optical aberrations have detrimental effects in multiphoton microscopy. These effects can be curtailed by implementing model-based wavefront sensorless adaptive optics, which only requires the addition of a wavefront shaping device, such as a deformable mirror (DM) to an existing microscope. The aberration correction is achieved by maximizing a suitable image quality metric. We implement a model-based aberration correction algorithm in a second-harmonic microscope. The tip, tilt, and defocus aberrations are removed from the basis functions used for the control of the DM, as these aberrations induce distortions in the acquired images. We compute the parameters of a quadratic polynomial that is used to model the image quality metric directly from experimental input-output measurements. Finally, we apply the aberration correction by maximizing the image quality metric using the least-squares estimate of the unknown aberration.

  11. Impact of N on the atomic-scale Sb distribution in quaternary GaAsSbN-capped InAs quantum dots

    PubMed Central

    2012-01-01

    The use of GaAsSbN capping layers on InAs/GaAs quantum dots (QDs) has recently been proposed for micro- and optoelectronic applications for their ability to independently tailor electron and hole confinement potentials. However, there is a lack of knowledge about the structural and compositional changes associated with the process of simultaneous Sb and N incorporation. In the present work, we have characterized using transmission electron microscopy techniques the effects of adding N in the GaAsSb/InAs/GaAs QD system. Firstly, strain maps of the regions away from the InAs QDs had revealed a huge reduction of the strain fields with the N incorporation but a higher inhomogeneity, which points to a composition modulation enhancement with the presence of Sb-rich and Sb-poor regions in the range of a few nanometers. On the other hand, the average strain in the QDs and surroundings is also similar in both cases. It could be explained by the accumulation of Sb above the QDs, compensating the tensile strain induced by the N incorporation together with an In-Ga intermixing inhibition. Indeed, compositional maps of column resolution from aberration-corrected Z-contrast images confirmed that the addition of N enhances the preferential deposition of Sb above the InAs QD, giving rise to an undulation of the growth front. As an outcome, the strong redshift in the photoluminescence spectrum of the GaAsSbN sample cannot be attributed only to the N-related reduction of the conduction band offset but also to an enhancement of the effect of Sb on the QD band structure. PMID:23181950

  12. Droplet-mediated formation of embedded GaAs nanowires in MBE GaAs(1-x)Bi(x) films.

    PubMed

    Wood, Adam W; Collar, Kristen; Li, Jincheng; Brown, April S; Babcock, Susan E

    2016-03-18

    We have examined the morphology and composition of embedded nanowires that can be formed during molecular beam epitaxy of GaAs(1-x)Bi(x) using high angle annular dark field ('Z-contrast') imaging in an aberration-corrected scanning transmission electron microscope. Samples were grown in Ga-rich growth conditions on a stationary GaAs substrate. Ga-rich droplets are observed on the surface with lateral trails extending from the droplet in the [110] direction. Cross-sectional scanning transmission electron microscopy of the film reveals epitaxial nanowire structures of composition ∼GaAs embedded in the GaAs(1-x)Bi(x) epitaxial layers. These nanowires extend from a surface droplet to the substrate at a shallow angle of inclination (∼4°). They typically are 4 μm long and have a lens-shaped cross section with major and minor axes dimensions of 800 and 120 nm. The top surface of the nanowires exhibits a linear trace in longitudinal cross-section, across which the composition change from ∼GaAs to GaAs(1-x)Bi(x) appears abrupt. The bottom surfaces of the nanowires appear wavy and the composition change appears to be graded over ∼25 nm. The droplets have phase separated into Ga- and Bi-rich components. A qualitative model is proposed in which Bi is gettered into Ga droplets, leaving Bi depleted nanowires in the wakes of the droplets as they migrate in one direction across the surface during GaAs(1-x)Bi(x) film growth.

  13. Image Processing

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Electronic Imagery, Inc.'s ImageScale Plus software, developed through a Small Business Innovation Research (SBIR) contract with Kennedy Space Flight Center for use on space shuttle Orbiter in 1991, enables astronauts to conduct image processing, prepare electronic still camera images in orbit, display them and downlink images to ground based scientists for evaluation. Electronic Imagery, Inc.'s ImageCount, a spin-off product of ImageScale Plus, is used to count trees in Florida orange groves. Other applications include x-ray and MRI imagery, textile designs and special effects for movies. As of 1/28/98, company could not be located, therefore contact/product information is no longer valid.

  14. Imaging genomics

    PubMed Central

    Thompson, Paul M.; Martin, Nicholas G.; Wright, Margaret J.

    2010-01-01

    Purpose of review Imaging genomics is an emerging field that is rapidly identifying genes that influence the brain, cognition, and risk for disease. Worldwide, thousands of individuals are being scanned with high-throughput genotyping (genome-wide scans), and new imaging techniques [high angular resolution diffusion imaging and resting state functional magnetic resonance imaging (MRI)] that provide fine-grained measures of the brain’s structural and functional connectivity. Along with clinical diagnosis and cognitive testing, brain imaging offers highly reproducible measures that can be subjected to genetic analysis. Recent findings Recent studies of twin, pedigree, and population-based datasets have discovered several candidate genes that consistently show small to moderate effects on brain measures. Many studies measure single phenotypes from the images, such as hippocampal volume, but voxel-wise genomic methods can plot the profile of genetic association at each 3D point in the brain. This exploits the full arsenal of imaging statistics to discover and replicate gene effects. Summary Imaging genomics efforts worldwide are now working together to discover and replicate many promising leads. By studying brain phenotypes closer to causative gene action, larger gene effects are detectable with realistic sample sizes obtainable from meta-analysis of smaller studies. Imaging genomics has broad applications to dementia, mental illness, and public health. PMID:20581684

  15. Body Imaging

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Magnetic Resonance Imaging (MRI) and Computer-aided Tomography (CT) images are often complementary. In most cases, MRI is good for viewing soft tissue but not bone, while CT images are good for bone but not always good for soft tissue discrimination. Physicians and engineers in the Department of Radiology at the University of Michigan Hospitals are developing a technique for combining the best features of MRI and CT scans to increase the accuracy of discriminating one type of body tissue from another. One of their research tools is a computer program called HICAP. The program can be used to distinguish between healthy and diseased tissue in body images.

  16. Multispectral imaging and image processing

    NASA Astrophysics Data System (ADS)

    Klein, Julie

    2014-02-01

    The color accuracy of conventional RGB cameras is not sufficient for many color-critical applications. One of these applications, namely the measurement of color defects in yarns, is why Prof. Til Aach and the Institute of Image Processing and Computer Vision (RWTH Aachen University, Germany) started off with multispectral imaging. The first acquisition device was a camera using a monochrome sensor and seven bandpass color filters positioned sequentially in front of it. The camera allowed sampling the visible wavelength range more accurately and reconstructing the spectra for each acquired image position. An overview will be given over several optical and imaging aspects of the multispectral camera that have been investigated. For instance, optical aberrations caused by filters and camera lens deteriorate the quality of captured multispectral images. The different aberrations were analyzed thoroughly and compensated based on models for the optical elements and the imaging chain by utilizing image processing. With this compensation, geometrical distortions disappear and sharpness is enhanced, without reducing the color accuracy of multispectral images. Strong foundations in multispectral imaging were laid and a fruitful cooperation was initiated with Prof. Bernhard Hill. Current research topics like stereo multispectral imaging and goniometric multispectral measure- ments that are further explored with his expertise will also be presented in this work.

  17. Blurred Image

    ERIC Educational Resources Information Center

    Conde, Maryse

    1975-01-01

    The growing influence of Western culture has greatly affected African women's status and image in the traditional society. Working women are confronted with the dilemma of preserving family traditions while changing their behavior and image to become members of the labor force. (MR)

  18. Diagnostic Imaging

    MedlinePlus

    Diagnostic imaging lets doctors look inside your body for clues about a medical condition. A variety of machines and techniques can create pictures of the structures and activities inside your body. The type of imaging your doctor uses depends on your symptoms and ...

  19. Cerenkov imaging.

    PubMed

    Das, Sudeep; Thorek, Daniel L J; Grimm, Jan

    2014-01-01

    Cerenkov luminescence (CL) has been used recently in a plethora of medical applications like imaging and therapy with clinically relevant medical isotopes. The range of medical isotopes used is fairly large and expanding. The generation of in vivo light is useful since it circumvents depth limitations for excitation light. Cerenkov luminescence imaging (CLI) is much cheaper in terms of infrastructure than positron emission tomography (PET) and is particularly useful for imaging of superficial structures. Imaging can basically be done using a sensitive camera optimized for low-light conditions, and it has a better resolution than any other nuclear imaging modality. CLI has been shown to effectively diagnose disease with regularly used PET isotope ((18)F-FDG) in clinical setting. Cerenkov luminescence tomography, Cerenkov luminescence endoscopy, and intraoperative Cerenkov imaging have also been explored with positive conclusions expanding the current range of applications. Cerenkov has also been used to improve PET imaging resolution since the source of both is the radioisotope being used. Smart imaging agents have been designed based on modulation of the Cerenkov signal using small molecules and nanoparticles giving better insight of the tumor biology. PMID:25287690

  20. Imaging Genetics

    ERIC Educational Resources Information Center

    Munoz, Karen E.; Hyde, Luke W.; Hariri, Ahmad R.

    2009-01-01

    Imaging genetics is an experimental strategy that integrates molecular genetics and neuroimaging technology to examine biological mechanisms that mediate differences in behavior and the risks for psychiatric disorder. The basic principles in imaging genetics and the development of the field are discussed.

  1. Imaging Atherosclerosis

    PubMed Central

    Tarkin, Jason M.; Dweck, Marc R.; Evans, Nicholas R.; Takx, Richard A.P.; Brown, Adam J.; Tawakol, Ahmed; Fayad, Zahi A.

    2016-01-01

    Advances in atherosclerosis imaging technology and research have provided a range of diagnostic tools to characterize high-risk plaque in vivo; however, these important vascular imaging methods additionally promise great scientific and translational applications beyond this quest. When combined with conventional anatomic- and hemodynamic-based assessments of disease severity, cross-sectional multimodal imaging incorporating molecular probes and other novel noninvasive techniques can add detailed interrogation of plaque composition, activity, and overall disease burden. In the catheterization laboratory, intravascular imaging provides unparalleled access to the world beneath the plaque surface, allowing tissue characterization and measurement of cap thickness with micrometer spatial resolution. Atherosclerosis imaging captures key data that reveal snapshots into underlying biology, which can test our understanding of fundamental research questions and shape our approach toward patient management. Imaging can also be used to quantify response to therapeutic interventions and ultimately help predict cardiovascular risk. Although there are undeniable barriers to clinical translation, many of these hold-ups might soon be surpassed by rapidly evolving innovations to improve image acquisition, coregistration, motion correction, and reduce radiation exposure. This article provides a comprehensive review of current and experimental atherosclerosis imaging methods and their uses in research and potential for translation to the clinic. PMID:26892971

  2. Image fusion

    NASA Technical Reports Server (NTRS)

    Pavel, M.

    1993-01-01

    The topics covered include the following: a system overview of the basic components of a system designed to improve the ability of a pilot to fly through low-visibility conditions such as fog; the role of visual sciences; fusion issues; sensor characterization; sources of information; image processing; and image fusion.

  3. Cerenkov Imaging

    PubMed Central

    Das, Sudeep; Thorek, Daniel L.J.; Grimm, Jan

    2014-01-01

    Cerenkov luminescence (CL) has been used recently in a plethora of medical applications like imaging and therapy with clinically relevant medical isotopes. The range of medical isotopes used is fairly large and expanding. The generation of in vivo light is useful since it circumvents depth limitations for excitation light. Cerenkov luminescence imaging (CLI) is much cheaper in terms of infrastructure than positron emission tomography (PET) and is particularly useful for imaging of superficial structures. Imaging can basically be done using a sensitive camera optimized for low-light conditions, and it has a better resolution than any other nuclear imaging modality. CLI has been shown to effectively diagnose disease with regularly used PET isotope (18F-FDG) in clinical setting. Cerenkov luminescence tomography, Cerenkov luminescence endoscopy, and intraoperative Cerenkov imaging have also been explored with positive conclusions expanding the current range of applications. Cerenkov has also been used to improve PET imaging resolution since the source of both is the radioisotope being used. Smart imaging agents have been designed based on modulation of the Cerenkov signal using small molecules and nanoparticles giving better insight of the tumor biology. PMID:25287690

  4. Retinal Imaging and Image Analysis

    PubMed Central

    Abràmoff, Michael D.; Garvin, Mona K.; Sonka, Milan

    2011-01-01

    Many important eye diseases as well as systemic diseases manifest themselves in the retina. While a number of other anatomical structures contribute to the process of vision, this review focuses on retinal imaging and image analysis. Following a brief overview of the most prevalent causes of blindness in the industrialized world that includes age-related macular degeneration, diabetic retinopathy, and glaucoma, the review is devoted to retinal imaging and image analysis methods and their clinical implications. Methods for 2-D fundus imaging and techniques for 3-D optical coherence tomography (OCT) imaging are reviewed. Special attention is given to quantitative techniques for analysis of fundus photographs with a focus on clinically relevant assessment of retinal vasculature, identification of retinal lesions, assessment of optic nerve head (ONH) shape, building retinal atlases, and to automated methods for population screening for retinal diseases. A separate section is devoted to 3-D analysis of OCT images, describing methods for segmentation and analysis of retinal layers, retinal vasculature, and 2-D/3-D detection of symptomatic exudate-associated derangements, as well as to OCT-based analysis of ONH morphology and shape. Throughout the paper, aspects of image acquisition, image analysis, and clinical relevance are treated together considering their mutually interlinked relationships. PMID:21743764

  5. Raman Imaging

    NASA Astrophysics Data System (ADS)

    Stewart, Shona; Priore, Ryan J.; Nelson, Matthew P.; Treado, Patrick J.

    2012-07-01

    The past decade has seen an enormous increase in the number and breadth of imaging techniques developed for analysis in many industries, including pharmaceuticals, food, and especially biomedicine. Rather than accept single-dimensional forms of information, users now demand multidimensional assessment of samples. High specificity and the need for little or no sample preparation make Raman imaging a highly attractive analytical technique and provide motivation for continuing advances in its supporting technology and utilization. This review discusses the current tools employed in Raman imaging, the recent advances, and the major applications in this ever-growing analytical field.

  6. Medical Imaging.

    ERIC Educational Resources Information Center

    Jaffe, C. Carl

    1982-01-01

    Describes principle imaging techniques, their applications, and their limitations in terms of diagnostic capability and possible adverse biological effects. Techniques include film radiography, computed tomography, nuclear medicine, positron emission tomography (PET), ultrasonography, nuclear magnetic resonance, and digital radiography. PET has…

  7. Body Imaging

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The high-tech art of digital signal processing (DSP) was pioneered at NASA's Jet Propulsion Laboratory (JPL) in the mid-1960s for use in the Apollo Lunar Landing Program. Designed to computer enhance pictures of the Moon, this technology became the basis for the Landsat Earth resources satellites and subsequently has been incorporated into a broad range of Earthbound medical and diagnostic tools. DSP is employed in advanced body imaging techniques including Computer-Aided Tomography, also known as CT and CATScan, and Magnetic Resonance Imaging (MRI). CT images are collected by irradiating a thin slice of the body with a fan-shaped x-ray beam from a number of directions around the body's perimeter. A tomographic (slice-like) picture is reconstructed from these multiple views by a computer. MRI employs a magnetic field and radio waves, rather than x-rays, to create images.

  8. Body Imaging

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The high-tech art of digital signal processing (DSP) was pioneered at NASA's Jet Propulsion Laboratory (JPL) in the mid-1960s for use in the Apollo Lunar Landing Program. Designed to computer enhance pictures of the Moon, this technology became the basis for the Landsat Earth resources satellites and subsequently has been incorporated into a broad range of Earthbound medical and diagnostic tools. DSP is employed in advanced body imaging techniques including Computer-Aided Tomography, also known as CT and CATScan, and Magnetic Resonance Imaging (MRI). CT images are collected by irradiating a thin slice of the body with a fan-shaped x-ray beam from a number of directions around the body's perimeter. A tomographic (slice-like) picture is reconstructed from these multiple views by a computer. MRI employs a magnetic field and radio waves, rather than x-rays, to create images. In this photograph, a patient undergoes an open MRI.

  9. Imaging System

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The 1100C Virtual Window is based on technology developed under NASA Small Business Innovation (SBIR) contracts to Ames Research Center. For example, under one contract Dimension Technologies, Inc. developed a large autostereoscopic display for scientific visualization applications. The Virtual Window employs an innovative illumination system to deliver the depth and color of true 3D imaging. Its applications include surgery and Magnetic Resonance Imaging scans, viewing for teleoperated robots, training, and in aviation cockpit displays.

  10. Diagnostic imaging.

    PubMed

    Morris, Peter; Perkins, Alan

    2012-04-21

    Physical techniques have always had a key role in medicine, and the second half of the 20th century in particular saw a revolution in medical diagnostic techniques with the development of key imaging instruments: x-ray imaging and emission tomography (nuclear imaging and PET), MRI, and ultrasound. These techniques use the full width of the electromagnetic spectrum, from gamma rays to radio waves, and sound. In most cases, the development of a medical imaging device was opportunistic; many scientists in physics laboratories were experimenting with simple x-ray images within the first year of the discovery of such rays, the development of the cyclotron and later nuclear reactors created the opportunity for nuclear medicine, and one of the co-inventors of MRI was initially attempting to develop an alternative to x-ray diffraction for the analysis of crystal structures. What all these techniques have in common is the brilliant insight of a few pioneering physical scientists and engineers who had the tenacity to develop their inventions, followed by a series of technical innovations that enabled the full diagnostic potential of these instruments to be realised. In this report, we focus on the key part played by these scientists and engineers and the new imaging instruments and diagnostic procedures that they developed. By bringing the key developments and applications together we hope to show the true legacy of physics and engineering in diagnostic medicine. PMID:22516558

  11. Possibilities and limitations of advanced transmission electron microscopy for carbon-based nanomaterials

    PubMed Central

    Bittencourt, Carla; Van Tendeloo, Gustaaf

    2015-01-01

    Summary A major revolution for electron microscopy in the past decade is the introduction of aberration correction, which enables one to increase both the spatial resolution and the energy resolution to the optical limit. Aberration correction has contributed significantly to the imaging at low operating voltages. This is crucial for carbon-based nanomaterials which are sensitive to electron irradiation. The research of carbon nanomaterials and nanohybrids, in particular the fundamental understanding of defects and interfaces, can now be carried out in unprecedented detail by aberration-corrected transmission electron microscopy (AC-TEM). This review discusses new possibilities and limits of AC-TEM at low voltage, including the structural imaging at atomic resolution, in three dimensions and spectroscopic investigation of chemistry and bonding. In situ TEM of carbon-based nanomaterials is discussed and illustrated through recent reports with particular emphasis on the underlying physics of interactions between electrons and carbon atoms. PMID:26425406

  12. Smart Acquisition EELS

    NASA Astrophysics Data System (ADS)

    Sader, K.; Schaffer, B.; Vaughan, G.; Wang, P.; Bleloch, A. L.; Brydson, R.; Brown, A.

    2010-07-01

    Electron energy loss (EEL) spectroscopy and high angle annular dark field (HAADF) imaging in aberration-corrected electron microscopes are powerful techniques to determine the chemical composition and structure of materials at atomic resolution. We have implemented Smart Acquisition, a flexible system of scanning transmission electron microsocpy (STEM) beam position control and EELS collection, on two aberration-corrected dedicated cold field emission gun (FEG) STEMs located at SuperSTEM, Daresbury Laboratory. This allows the collection of EEL spectra from spatially defined areas with a much lower electron dose possible than existing techniques such as spectrum imaging.

  13. Stellar Imager

    NASA Technical Reports Server (NTRS)

    Carpenter, Kenneth

    2007-01-01

    The Stellar Imager (SI) is one of NASA's "Vision Missions" - concepts for future, space-based, strategic missions that could enormously increase our capabilities for observing the Cosmos. SI is designed as a UV/Optical Interferometer which will enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and, via asteroseismology, stellar interiors and of the Universe in general. The ultra-sharp images of the Stellar Imager will revolutionize our view of many dynamic astrophysical processes by transforming point sources into extended sources, and snapshots into evolving views. SI, with a characteristic angular resolution of 0.1 milli-arcseconds at 2000 Angstroms, represents an advance in image detail of several hundred times over that provided by the Hubble Space Telescope. The Stellar Imager will zoom in on what today-with few exceptions - we only know as point sources, revealing processes never before seen, thus providing a tool as fundamental to astrophysics as the microscope is to the study of life on Earth. SI's science focuses on the role of magnetism in the Universe, particularly on magnetic activity on the surfaces of stars like the Sun. It's prime goal is to enable long-term forecasting of solar activity and the space weather that it drives, in support of the Living With a Star program in the Exploration Era. SI will also revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes in the Universe. Stellar Imager is included as a "Flagship and Landmark Discovery Mission" in the 2005 Sun Solar System Connection (SSSC) Roadmap and as a candidate for a "Pathways to Life Observatory" in the Exploration of the Universe Division (EUD) Roadmap (May, 2005) and as such is a candidate mission for the 2025-2030 timeframe. An artist's drawing of the current "baseline" concept for SI is presented.

  14. Medical imaging

    NASA Astrophysics Data System (ADS)

    Elliott, Alex

    2005-07-01

    Diagnostic medical imaging is a fundamental part of the practice of modern medicine and is responsible for the expenditure of considerable amounts of capital and revenue monies in healthcare systems around the world. Much research and development work is carried out, both by commercial companies and the academic community. This paper reviews briefly each of the major diagnostic medical imaging techniques—X-ray (planar and CT), ultrasound, nuclear medicine (planar, SPECT and PET) and magnetic resonance. The technical challenges facing each are highlighted, with some of the most recent developments. In terms of the future, interventional/peri-operative imaging, the advancement of molecular medicine and gene therapy are identified as potential areas of expansion.

  15. Imaging Hemodynamics

    PubMed Central

    Jennings, Dominique; Raghunand, Natarajan; Gillies, Robert J.

    2014-01-01

    Microvascular permeability is a pharmacologic indicator of tumor response to therapy, and it is expected that this biomarker will evolve into a clinical surrogate endpoint and be integrated into protocols for determining patient response to antiangiogenic or antivascular therapies. This review discusses the physiological context of vessel permeability in an imaging setting, how it is affected by active and passive transport mechanisms, and how it is described mathematically for both theoretical and complex dynamic microvessel membranes. Many research groups have established dynamic-enhanced imaging protocols for estimating this important parameter. This review discusses those imaging modalities, the advantages and disadvantages of each, and how they compare in terms of their ability to deliver information about therapy-associated changes in microvessel permeability in humans. Finally, this review discusses future directions and improvements needed in these areas. PMID:18506397

  16. Angiographic Imaging

    PubMed Central

    Morris, D. Christopher

    1986-01-01

    Angiographic imaging in 1986 employs not only conventional film arteriography and venography, but also digital subtraction angiography (DSA). Arteriography is still the best method of demonstrating pathology in patients with peripheral vascular disease. Transluminal angioplasty, its indications and results are discussed. Patients with suspected renovascular hypertension should be given intravenous DSA and, if pathology is demonstrated, renin sampling as well. Patients with severe, acute, life-threatening hemorrhage may have angiography not only to localize bleeding sites, but also to treat them by transcatheter embolization techniques. Various other angiographic techniques including venous sampling are discussed briefly. ImagesFigure 2Figure 3Figure 4Figure 5Figure 6Figure 7 PMID:21267204

  17. Musculoskeletal Imaging

    PubMed Central

    Connell, Douglas G.

    1986-01-01

    Musculoskeletal problems account for a significant portion of primary care medicine. Increase in the public awareness of physical fitness has led to an increase in both the incidence and appreciation of musculoskeletal disorders. This discussion considers the investigation of disorders involving the shoulder, wrist, foot, knee and pelvis. Emphasis is placed on new imaging techniques and their place in the investigation of these problems, as well as on their relationship to the more traditional modalities. ImagesFigure 1Figure 2Figure 3Figure 4Figure 5Figure 6Figure 7Figure 8Figure 9 PMID:21267198

  18. Brain Imaging

    PubMed Central

    Racine, Eric; Bar-Ilan, Ofek; Illes, Judy

    2007-01-01

    Advances in neuroscience are increasingly intersecting with issues of ethical, legal, and social interest. This study is an analysis of press coverage of an advanced technology for brain imaging, functional magnetic resonance imaging, that has gained significant public visibility over the past ten years. Discussion of issues of scientific validity and interpretation dominated over ethical content in both the popular and specialized press. Coverage of research on higher order cognitive phenomena specifically attributed broad personal and societal meaning to neuroimages. The authors conclude that neuroscience provides an ideal model for exploring science communication and ethics in a multicultural context. PMID:17330151

  19. Imaging sciences workshop

    SciTech Connect

    Candy, J.V.

    1994-11-15

    This workshop on the Imaging Sciences sponsored by Lawrence Livermore National Laboratory contains short abstracts/articles submitted by speakers. The topic areas covered include the following: Astronomical Imaging; biomedical imaging; vision/image display; imaging hardware; imaging software; Acoustic/oceanic imaging; microwave/acoustic imaging; computed tomography; physical imaging; imaging algorithms. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  20. Biblical Images.

    ERIC Educational Resources Information Center

    Nir, Yeshayahu

    1987-01-01

    Responds to Marjorie Munsterberg's review of "The Bible and the Image: The History of Photography in the Holy Land 1839-1899." Claims that Munsterberg provided an incomplete and inaccurate knowledge of the book's content, and that she considered Western pictorial traditions as the only valid measure in the study of the history of photography.…

  1. [Endometrial imaging].

    PubMed

    Lemercier, E; Genevois, A; Dacher, J N; Benozio, M; Descargues, G; Marpeau, L

    2000-12-01

    The diagnostic value of endovaginal sonography in benign or malignant endometrial pathology is high, increased by sonohysterography. Sonohysterography is useful in the diagnosis of endometrial thickness and to determine further investigations. MRI is accurate in the uterine adenomyosis diagnosis and is the imaging modality of choice for the preoperative endometrial cancer staging. PMID:11173754

  2. Narrowband Imaging

    NASA Astrophysics Data System (ADS)

    Goldman, Don S.

    The Hubble Space Telescope (HST) captured the attention of the world when it released its astounding image in 1995 of the Eagle Nebula (Messier 16) often called "The Pillars of Creation" (Fig. 1). It contained dark, billowing towers of gas and dust rising majestically into a background of glowing radiation. It told a story of new star formation.

  3. Inner Image

    ERIC Educational Resources Information Center

    Mollhagen, Nancy

    2004-01-01

    In this article, the author states that she has always loved self portraits but most teenagers do not enjoy looking too closely at their own faces in an effort to replicate them. Thanks to a new digital camera, she was able to use this new technology to inspire students to take a closer look at their inner image. Prior to the self-portrait…

  4. Forest Imaging

    NASA Technical Reports Server (NTRS)

    1992-01-01

    NASA's Technology Applications Center, with other government and academic agencies, provided technology for improved resources management to the Cibola National Forest. Landsat satellite images enabled vegetation over a large area to be classified for purposes of timber analysis, wildlife habitat, range measurement and development of general vegetation maps.

  5. Photoacoustic imaging platforms for multimodal imaging

    PubMed Central

    2015-01-01

    Photoacoustic (PA) imaging is a hybrid biomedical imaging method that exploits both acoustical Epub ahead of print and optical properties and can provide both functional and structural information. Therefore, PA imaging can complement other imaging methods, such as ultrasound imaging, fluorescence imaging, optical coherence tomography, and multi-photon microscopy. This article reviews techniques that integrate PA with the above imaging methods and describes their applications. PMID:25754364

  6. Operation of TEAM I in a user environment at NCEM.

    PubMed

    Ercius, Peter; Boese, Markus; Duden, Thomas; Dahmen, Ulrich

    2012-08-01

    TEAM I is the final product of the Transmission Electron Aberration-corrected Microscope (TEAM) Project, a collaborative project funded by the Department of Energy with the goal of designing and building a platform for a next generation aberration-corrected electron microscope capable of image resolution of up to 50 pm. The TEAM instrument incorporates a number of new technologies, including spherical- and chromatic-aberration correction, an all-piezo-electric sample stage and an active-pixel direct electron detector. This article describes the functionality of this advanced instrumentation, its response to changes in environment or operating conditions, and its stability during daily operation within the National Center for Electron Microscopy user facility. PMID:22849797

  7. Quantitative ADF STEM: acquisition, analysis and interpretation

    NASA Astrophysics Data System (ADS)

    Jones, L.

    2016-01-01

    Quantitative annular dark-field in the scanning transmission electron microscope (ADF STEM), where image intensities are used to provide composition and thickness measurements, has enjoyed a renaissance during the last decade. Now in a post aberration-correction era many aspects of the technique are being revisited. Here the recent progress and emerging best-practice for such aberration corrected quantitative ADF STEM is discussed including issues relating to proper acquisition of experimental data and its calibration, approaches for data analysis, the utility of such data, its interpretation and limitations.

  8. Imaging bolometer

    DOEpatents

    Wurden, G.A.

    1999-01-19

    Radiation-hard, steady-state imaging bolometer is disclosed. A bolometer employing infrared (IR) imaging of a segmented-matrix absorber of plasma radiation in a cooled-pinhole camera geometry is described. The bolometer design parameters are determined by modeling the temperature of the foils from which the absorbing matrix is fabricated by using a two-dimensional time-dependent solution of the heat conduction equation. The resulting design will give a steady-state bolometry capability, with approximately 100 Hz time resolution, while simultaneously providing hundreds of channels of spatial information. No wiring harnesses will be required, as the temperature-rise data will be measured via an IR camera. The resulting spatial data may be used to tomographically investigate the profile of plasmas. 2 figs.

  9. Imaging bolometer

    SciTech Connect

    Wurden, Glen A.

    1999-01-01

    Radiation-hard, steady-state imaging bolometer. A bolometer employing infrared (IR) imaging of a segmented-matrix absorber of plasma radiation in a cooled-pinhole camera geometry is described. The bolometer design parameters are determined by modeling the temperature of the foils from which the absorbing matrix is fabricated by using a two-dimensional time-dependent solution of the heat conduction equation. The resulting design will give a steady-state bolometry capability, with approximately 100 Hz time resolution, while simultaneously providing hundreds of channels of spatial information. No wiring harnesses will be required, as the temperature-rise data will be measured via an IR camera. The resulting spatial data may be used to tomographically investigate the profile of plasmas.

  10. Attosecond imaging.

    PubMed

    Vrakking, Marc J J

    2014-02-21

    The natural timescale for electron dynamics reaches down to the attosecond domain. Following the discovery of attosecond laser pulses, about a decade ago, attosecond science has developed into a vibrant, new research field, where the motion of single or multiple electrons and, in molecules, the coupling of electronic and nuclear motion, can be investigated, on attosecond to few-femtosecond timescales. Attosecond experiments require suitable observables. This review describes how "attosecond imaging", basing itself on kinetic energy and angle-resolved detection of photoelectrons and fragment ions using a velocity map imaging (VMI) spectrometer, has been exploited in a number of pump-probe experiments. The use of a VMI spectrometer in attosecond experiments has allowed the characterization of attosecond pulse trains and isolated attosecond pulses, the elucidation of continuum electron dynamics and wave packet interferometry in atomic photoionization and the observation of electron localization in dissociative molecular photoionization. PMID:24398785

  11. Brain imaging

    SciTech Connect

    Bradshaw, J.R.

    1989-01-01

    This book presents a survey of the various imaging tools with examples of the different diseases shown best with each modality. It includes 100 case presentations covering the gamut of brain diseases. These examples are grouped according to the clinical presentation of the patient: headache, acute headache, sudden unilateral weakness, unilateral weakness of gradual onset, speech disorders, seizures, pituitary and parasellar lesions, sensory disorders, posterior fossa and cranial nerve disorders, dementia, and congenital lesions.

  12. Imaging stress.

    PubMed

    Brielle, Shlomi; Gura, Rotem; Kaganovich, Daniel

    2015-11-01

    Recent innovations in cell biology and imaging approaches are changing the way we study cellular stress, protein misfolding, and aggregation. Studies have begun to show that stress responses are even more variegated and dynamic than previously thought, encompassing nano-scale reorganization of cytosolic machinery that occurs almost instantaneously, much faster than transcriptional responses. Moreover, protein and mRNA quality control is often organized into highly dynamic macromolecular assemblies, or dynamic droplets, which could easily be mistaken for dysfunctional "aggregates," but which are, in fact, regulated functional compartments. The nano-scale architecture of stress-response ranges from diffraction-limited structures like stress granules, P-bodies, and stress foci to slightly larger quality control inclusions like juxta nuclear quality control compartment (JUNQ) and insoluble protein deposit compartment (IPOD), as well as others. Examining the biochemical and physical properties of these dynamic structures necessitates live cell imaging at high spatial and temporal resolution, and techniques to make quantitative measurements with respect to movement, localization, and mobility. Hence, it is important to note some of the most recent observations, while casting an eye towards new imaging approaches that offer the possibility of collecting entirely new kinds of data from living cells.

  13. Imaging Borrelly

    USGS Publications Warehouse

    Soderblom, L.A.; Boice, D.C.; Britt, D.T.; Brown, R.H.; Buratti, B.J.; Kirk, R.L.; Lee, M.; Nelson, R.M.; Oberst, J.; Sandel, B.R.; Stern, S.A.; Thomas, N.; Yelle, R.V.

    2004-01-01

    The nucleus, coma, and dust jets of short-period Comet 19P/Borrelly were imaged from the Deep Space 1 spacecraft during its close flyby in September 2001. A prominent jet dominated the near-nucleus coma and emanated roughly normal to the long axis of nucleus from a broad central cavity. We show it to have remained fixed in position for more than 34 hr, much longer than the 26-hr rotation period. This confirms earlier suggestions that it is co-aligned with the rotation axis. From a combination of fitting the nucleus light curve from approach images and the nucleus' orientation from stereo images at encounter, we conclude that the sense of rotation is right-handed around the main jet vector. The inferred rotation pole is approximately perpendicular to the long axis of the nucleus, consistent with a simple rotational state. Lacking an existing IAU comet-specific convention but applying a convention provisionally adopted for asteroids, we label this the north pole. This places the sub-solar latitude at ???60?? N at the time of the perihelion with the north pole in constant sunlight and thus receiving maximum average insolation. ?? 2003 Elsevier Inc. All rights reserved.

  14. Imaging and radiology

    MedlinePlus

    ... imaging or a PET scan Ultrasound INTERVENTIONAL RADIOLOGY Interventional radiologists are doctors that use imaging such as CT, ultrasound, MRI and fluoroscopy to help guide procedures. The imaging ...

  15. Image Editing Via Searching Source Image

    NASA Astrophysics Data System (ADS)

    Yu, Han; Deng, Liang-Jian

    Image editing has important applications by changing the image texture, illumination, target location, etc. As an important application of Poisson equation, Poisson image editing processes images on the gradient domain and has been applied to seamless clone, selection editing, image denoising, etc. In this paper, we present a new application of Poisson image editing, which is based on searching source image. The main feature of the new application is all modifying information comes from the source image. Experimental results show that the proposed application performs well.

  16. Chest Imaging.

    PubMed

    Keijsers, Ruth G; Veltkamp, Marcel; Grutters, Jan C

    2015-12-01

    Chest imaging has a central role in the diagnosis and monitoring of sarcoidosis. For staging of pulmonary disease on chest radiograph, Scadding stages are still widely used. High-resolution CT (HRCT), however, is more accurate in visualizing the various manifestations of pulmonary sarcoidosis as well its complications. A generally accepted HRCT scoring system is lacking. Fluorodeoxyglucose F 18 positron emission tomography can visualize disease activity better than conventional makers in a significant proportion of patients. In patients with extensive changes on HRCT but no parenchymal fluorodeoxyglucose F 18 uptake, prudence with regard to initiation or intensification of immunosuppressive treatment is warranted. PMID:26593136

  17. Image Processor

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Texas Instruments Programmable Remapper is a research tool used to determine how to best utilize the part of a patient's visual field still usable by mapping onto his field of vision with manipulated imagery. It is an offshoot of a NASA program for speeding up, improving the accuracy of pattern recognition in video imagery. The Remapper enables an image to be "pushed around" so more of it falls into the functional portions in the retina of a low vision person. It works at video rates, and researchers hope to significantly reduce its size and cost, creating a wearable prosthesis for visually impaired people.

  18. Scrotal imaging

    PubMed Central

    Studniarek, Michał; Modzelewska, Elza

    2015-01-01

    Pathological lesions within the scrotum are relatively rare in imaging except for ultrasonography. The diseases presented in the paper are usually found in men at the age of 15–45, i.e. men of reproductive age, and therefore they are worth attention. Scrotal ultrasound in infertile individuals should be conducted on a routine basis owing to the fact that pathological scrotal lesions are frequently detected in this population. Malignant testicular cancers are the most common neoplasms in men at the age of 20–40. Ultrasound imaging is the method of choice characterized by the sensitivity of nearly 100% in the differentiation between intratesticular and extratesticular lesions. In the case of doubtful lesions that are not classified for intra-operative verification, nuclear magnetic resonance is applied. Computed tomography, however, is performed to monitor the progression of a neoplastic disease, in pelvic trauma with scrotal injury as well as in rare cases of scrotal hernias involving the ureters or a fragment of the urinary bladder. PMID:26674847

  19. Indexing Images: Testing an Image Description Template.

    ERIC Educational Resources Information Center

    Jorgensen, Corinne

    1996-01-01

    A template for pictorial image description to be used by novice image searchers in recording their descriptions of images was tested; image attribute classes derived in previous research were used to model the template. Results indicated that users may need training and/or more guidance to correctly assign descriptors to higher-level classes.…

  20. Speckle imaging algorithms for planetary imaging

    SciTech Connect

    Johansson, E.

    1994-11-15

    I will discuss the speckle imaging algorithms used to process images of the impact sites of the collision of comet Shoemaker-Levy 9 with Jupiter. The algorithms use a phase retrieval process based on the average bispectrum of the speckle image data. High resolution images are produced by estimating the Fourier magnitude and Fourier phase of the image separately, then combining them and inverse transforming to achieve the final result. I will show raw speckle image data and high-resolution image reconstructions from our recent experiment at Lick Observatory.

  1. Image resampling effects in mammographic image simulation.

    PubMed

    Yip, M; Mackenzie, A; Lewis, E; Dance, D R; Young, K C; Christmas, W; Wells, K

    2011-11-21

    This work describes the theory of resampling effects within the context of image simulation for mammographic images. The process of digitization associated with using digital imaging technology needs to be correctly addressed in any image simulation process. Failure to do so can lead to overblurring in the final synthetic image. A method for weighted neighbourhood averaging is described for non-integer scaling factors in resampling images. The use of the method is demonstrated by comparing simulated and real images of an edge test object acquired on two clinical mammography systems. Images were simulated using two setups: from idealized images and from images obtained with clinical systems. A Gaussian interpolation method is proposed as a single-step solution to modelling blurring filters for the simulation process.

  2. Reversible wurtzite-tetragonal reconstruction in ZnO(1010) surfaces.

    PubMed

    He, Mo-Rigen; Yu, Rong; Zhu, Jing

    2012-07-27

    Bistable surface: The reversible phase transition between wurtzite (WZ) and body-centered-tetragonal (BCT) lattice was activated in ZnO(1010) surfaces and directly imaged at atomic scale by using aberration-corrected electron microscopy. A nucleation-growth mechanism for the surface reconstruction is further proposed based on observations and calculations of the WZ-BCT domain boundary.

  3. Atomic Resolution of the Structure of a Metal Support Interface: Triosmium Clusters on MgO (110)

    SciTech Connect

    Browning, Nigel D.; Chi, Miaofang; Gates, Bruce C.; kulkarni, Apoorva; Ortalan, Volkan

    2010-01-01

    Aberration-corrected STEM images of MgO-supported triosmium clusters show that the osmium atoms reside atop magnesium atoms. On the basis of the results, structural models of the clusters that include the metal-support interaction are derived.

  4. Reversible digital images

    NASA Astrophysics Data System (ADS)

    Knox, Keith T.

    1999-04-01

    A method has been developed to hide one image inside another with little loss in image quality. If the second image is a logo or watermark, then this method may be used to protect the ownership rights of the first image and to guarantee the authenticity of the image. The two images to be combined may be either black & white or color continuous tone images. A reversible image is created by incorporating the first image in the upper 4 bits and the second image in the lower 4 bits. When viewed normally, the reversible image appears to be the first image. To view the hidden image, the bits of the combined image are reversed, exchanging all of the lower and higher order bits. When viewed in the reversed mode, the image appears to be the second or hidden image. To maintain a high level of image quality for both images, two simultaneous error diffusion calculations are run to ensure that both views of the reversible image have the same visual appearance as the originals. Any alteration of one of the images locally destroys the other image at the site of the alterations. This provides a method to detect alterations of the original image.

  5. scikit-image: image processing in Python

    PubMed Central

    Schönberger, Johannes L.; Nunez-Iglesias, Juan; Boulogne, François; Warner, Joshua D.; Yager, Neil; Gouillart, Emmanuelle; Yu, Tony

    2014-01-01

    scikit-image is an image processing library that implements algorithms and utilities for use in research, education and industry applications. It is released under the liberal Modified BSD open source license, provides a well-documented API in the Python programming language, and is developed by an active, international team of collaborators. In this paper we highlight the advantages of open source to achieve the goals of the scikit-image library, and we showcase several real-world image processing applications that use scikit-image. More information can be found on the project homepage, http://scikit-image.org. PMID:25024921

  6. scikit-image: image processing in Python.

    PubMed

    van der Walt, Stéfan; Schönberger, Johannes L; Nunez-Iglesias, Juan; Boulogne, François; Warner, Joshua D; Yager, Neil; Gouillart, Emmanuelle; Yu, Tony

    2014-01-01

    scikit-image is an image processing library that implements algorithms and utilities for use in research, education and industry applications. It is released under the liberal Modified BSD open source license, provides a well-documented API in the Python programming language, and is developed by an active, international team of collaborators. In this paper we highlight the advantages of open source to achieve the goals of the scikit-image library, and we showcase several real-world image processing applications that use scikit-image. More information can be found on the project homepage, http://scikit-image.org.

  7. X-Ray Imaging

    MedlinePlus

    ... Brain Surgery Imaging Clinical Trials Basics Patient Information X-Ray Imaging Print This Page X-ray imaging is perhaps the most familiar type of imaging. Images produced by X-rays are due to the different absorption rates of ...

  8. Split image optical display

    DOEpatents

    Veligdan, James T.

    2007-05-29

    A video image is displayed from an optical panel by splitting the image into a plurality of image components, and then projecting the image components through corresponding portions of the panel to collectively form the image. Depth of the display is correspondingly reduced.

  9. Split image optical display

    DOEpatents

    Veligdan, James T.

    2005-05-31

    A video image is displayed from an optical panel by splitting the image into a plurality of image components, and then projecting the image components through corresponding portions of the panel to collectively form the image. Depth of the display is correspondingly reduced.

  10. Smart Image Enhancement Process

    NASA Technical Reports Server (NTRS)

    Jobson, Daniel J. (Inventor); Rahman, Zia-ur (Inventor); Woodell, Glenn A. (Inventor)

    2012-01-01

    Contrast and lightness measures are used to first classify the image as being one of non-turbid and turbid. If turbid, the original image is enhanced to generate a first enhanced image. If non-turbid, the original image is classified in terms of a merged contrast/lightness score based on the contrast and lightness measures. The non-turbid image is enhanced to generate a second enhanced image when a poor contrast/lightness score is associated therewith. When the second enhanced image has a poor contrast/lightness score associated therewith, this image is enhanced to generate a third enhanced image. A sharpness measure is computed for one image that is selected from (i) the non-turbid image, (ii) the first enhanced image, (iii) the second enhanced image when a good contrast/lightness score is associated therewith, and (iv) the third enhanced image. If the selected image is not-sharp, it is sharpened to generate a sharpened image. The final image is selected from the selected image and the sharpened image.

  11. What Is an Image?

    ERIC Educational Resources Information Center

    Gerber, Andrew J.; Peterson, Bradley S.

    2008-01-01

    The article helps to understand the interpretation of an image by presenting as to what constitutes an image. A common feature in all images is the basic physical structure that can be described with a common set of terms.

  12. To Image...or Not to Image?

    ERIC Educational Resources Information Center

    Bruley, Karina

    1996-01-01

    Provides a checklist of considerations for installing document image processing with an electronic document management system. Other topics include scanning; indexing; the image file life cycle; benefits of imaging; document-driven workflow; and planning for workplace changes like postsorting, creating a scanning room, redeveloping job tasks and…

  13. Filter for biomedical imaging and image processing

    NASA Astrophysics Data System (ADS)

    Mondal, Partha P.; Rajan, K.; Ahmad, Imteyaz

    2006-07-01

    Image filtering techniques have numerous potential applications in biomedical imaging and image processing. The design of filters largely depends on the a priori, knowledge about the type of noise corrupting the image. This makes the standard filters application specific. Widely used filters such as average, Gaussian, and Wiener reduce noisy artifacts by smoothing. However, this operation normally results in smoothing of the edges as well. On the other hand, sharpening filters enhance the high-frequency details, making the image nonsmooth. An integrated general approach to design a finite impulse response filter based on Hebbian learning is proposed for optimal image filtering. This algorithm exploits the interpixel correlation by updating the filter coefficients using Hebbian learning. The algorithm is made iterative for achieving efficient learning from the neighborhood pixels. This algorithm performs optimal smoothing of the noisy image by preserving high-frequency as well as low-frequency features. Evaluation results show that the proposed finite impulse response filter is robust under various noise distributions such as Gaussian noise, salt-and-pepper noise, and speckle noise. Furthermore, the proposed approach does not require any a priori knowledge about the type of noise. The number of unknown parameters is few, and most of these parameters are adaptively obtained from the processed image. The proposed filter is successfully applied for image reconstruction in a positron emission tomography imaging modality. The images reconstructed by the proposed algorithm are found to be superior in quality compared with those reconstructed by existing PET image reconstruction methodologies.

  14. Imaging of testicular tumours.

    PubMed

    Owens, E J; Kabala, J; Goddard, P

    2004-01-01

    This article reviews the diagnosis, pathology and imaging of testicular tumours, predominantly germ cell tumours. It will discuss the imaging techniques used in their diagnosis, staging and surveillance.

  15. Far Ultraviolet Imaging from the Image Spacecraft

    NASA Technical Reports Server (NTRS)

    Mende, S. B.; Heetderks, H.; Frey, H. U.; Lampton, M.; Geller, S. P.; Stock, J. M.; Abiad, R.; Siegmund, O. H. W.; Tremsin, A. S.; Habraken, S.

    2000-01-01

    Direct imaging of the magnetosphere by the IMAGE spacecraft will be supplemented by observation of the global aurora. The IMAGE satellite instrument complement includes three Far Ultraviolet (FUV) instruments. The Wideband Imaging Camera (WIC) will provide broad band ultraviolet images of the aurora for maximum spatial and temporal resolution by imaging the LBH N2 bands of the aurora. The Spectrographic Imager (SI), a novel form of monochromatic imager, will image the aurora, filtered by wavelength. The proton-induced component of the aurora will be imaged separately by measuring the Doppler-shifted Lyman-a. Finally, the GEO instrument will observe the distribution of the geocoronal emission to obtain the neutral background density source for charge exchange in the magnetosphere. The FUV instrument complement looks radially outward from the rotating IMAGE satellite and, therefore, it spends only a short time observing the aurora and the Earth during each spin. To maximize photon collection efficiency and use efficiently the short time available for exposures the FUV auroral imagers WIC and SI both have wide fields of view and take data continuously as the auroral region proceeds through the field of view. To minimize data volume, the set of multiple images are electronically co-added by suitably shifting each image to compensate for the spacecraft rotation. In order to minimize resolution loss, the images have to be distort ion-corrected in real time. The distortion correction is accomplished using high speed look up tables that are pre-generated by least square fitting to polynomial functions by the on-orbit processor. The instruments were calibrated individually while on stationary platforms, mostly in vacuum chambers. Extensive ground-based testing was performed with visible and near UV simulators mounted on a rotating platform to emulate their performance on a rotating spacecraft.

  16. Image processing and recognition for biological images

    PubMed Central

    Uchida, Seiichi

    2013-01-01

    This paper reviews image processing and pattern recognition techniques, which will be useful to analyze bioimages. Although this paper does not provide their technical details, it will be possible to grasp their main tasks and typical tools to handle the tasks. Image processing is a large research area to improve the visibility of an input image and acquire some valuable information from it. As the main tasks of image processing, this paper introduces gray-level transformation, binarization, image filtering, image segmentation, visual object tracking, optical flow and image registration. Image pattern recognition is the technique to classify an input image into one of the predefined classes and also has a large research area. This paper overviews its two main modules, that is, feature extraction module and classification module. Throughout the paper, it will be emphasized that bioimage is a very difficult target for even state-of-the-art image processing and pattern recognition techniques due to noises, deformations, etc. This paper is expected to be one tutorial guide to bridge biology and image processing researchers for their further collaboration to tackle such a difficult target. PMID:23560739

  17. Modern Brain Tumor Imaging

    PubMed Central

    Barajas, Ramon F.; Cha, Soonmee

    2015-01-01

    The imaging and clinical management of patients with brain tumor continue to evolve over time and now heavily rely on physiologic imaging in addition to high-resolution structural imaging. Imaging remains a powerful noninvasive tool to positively impact the management of patients with brain tumor. This article provides an overview of the current state-of-the art clinical brain tumor imaging. In this review, we discuss general magnetic resonance (MR) imaging methods and their application to the diagnosis of, treatment planning and navigation, and disease monitoring in patients with brain tumor. We review the strengths, limitations, and pitfalls of structural imaging, diffusion-weighted imaging techniques, MR spectroscopy, perfusion imaging, positron emission tomography/MR, and functional imaging. Overall this review provides a basis for understudying the role of modern imaging in the care of brain tumor patients. PMID:25977902

  18. Quantum ghost imaging experiments

    NASA Astrophysics Data System (ADS)

    Meyers, Ronald E.; Deacon, Keith S.

    2009-08-01

    Since the first experiment achieving quantum ghost imaging of an opaque object, performed by the authors at the Army Research Laboratory, ghost imaging research has increased. That physics experiment resulting in the image of toy soldier created a new imaging paradigm. Prior to that all images of opaque objects were made by receiving patterns of the object from reflection and scattering of the light into a camera. In the ghost imaging experiment light patterns only came from the light source and the image was made from coincidences of those and photon counts of reflected and scattered photons received from the object. Since that original ghost imaging experiment, approximately thirteen years after ghost imaging of transmissive objects was introduced, ghost imaging is providing a new and proweful quantum tool for future improved imaging missions in the environment.

  19. Imaging Sciences Workshop Proceedings

    SciTech Connect

    Candy, J.V.

    1996-11-21

    This report contains the proceedings of the Imaging Sciences Workshop sponsored by C.A.S.LS., the Center for Advanced Signal & Image Sciences. The Center, established primarily to provide a forum where researchers can freely exchange ideas on the signal and image sciences in a comfortable intellectual environment, has grown over the last two years with the opening of a Reference Library (located in Building 272). The Technical Program for the 1996 Workshop include a variety of efforts in the Imaging Sciences including applications in the Microwave Imaging, highlighted by the Micro-Impulse Radar (MIR) system invented at LLNL, as well as other applications in this area. Special sessions organized by various individuals in Speech, Acoustic Ocean Imaging, Radar Ocean Imaging, Ultrasonic Imaging, and Optical Imaging discuss various applica- tions of real world problems. For the more theoretical, sessions on Imaging Algorithms and Computed Tomography were organized as well as for the more pragmatic featuring a session on Imaging Systems.

  20. Image management research

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.

    1988-01-01

    Two types of research issues are involved in image management systems with space station applications: image processing research and image perception research. The image processing issues are the traditional ones of digitizing, coding, compressing, storing, analyzing, and displaying, but with a new emphasis on the constraints imposed by the human perceiver. Two image coding algorithms have been developed that may increase the efficiency of image management systems (IMS). Image perception research involves a study of the theoretical and practical aspects of visual perception of electronically displayed images. Issues include how rapidly a user can search through a library of images, how to make this search more efficient, and how to present images in terms of resolution and split screens. Other issues include optimal interface to an IMS and how to code images in a way that is optimal for the human perceiver. A test-bed within which such issues can be addressed has been designed.

  1. Multiscale Image Processing of Solar Image Data

    NASA Astrophysics Data System (ADS)

    Young, C.; Myers, D. C.

    2001-12-01

    It is often said that the blessing and curse of solar physics is too much data. Solar missions such as Yohkoh, SOHO and TRACE have shown us the Sun with amazing clarity but have also increased the amount of highly complex data. We have improved our view of the Sun yet we have not improved our analysis techniques. The standard techniques used for analysis of solar images generally consist of observing the evolution of features in a sequence of byte scaled images or a sequence of byte scaled difference images. The determination of features and structures in the images are done qualitatively by the observer. There is little quantitative and objective analysis done with these images. Many advances in image processing techniques have occured in the past decade. Many of these methods are possibly suited for solar image analysis. Multiscale/Multiresolution methods are perhaps the most promising. These methods have been used to formulate the human ability to view and comprehend phenomena on different scales. So these techniques could be used to quantitify the imaging processing done by the observers eyes and brains. In this work we present several applications of multiscale techniques applied to solar image data. Specifically, we discuss uses of the wavelet, curvelet, and related transforms to define a multiresolution support for EIT, LASCO and TRACE images.

  2. Image processor development with synthetic images

    NASA Astrophysics Data System (ADS)

    Guivens, Norman R., Jr.; Henshaw, Philip D.

    1992-03-01

    Many impressive developments in image simulation technology have led to extensive use of synthetic images in the motion picture industry for special effects and animation, and also in applications such as aircraft flight simulators. Although these images appear correct to the human eye, they generally are not suitable for development of image processing and machine vision applications because the logarithmic response of the human eye does not match the linear response of most electronic detectors. Synthetic images must accurately represent the effects which are present in detected images, whether produced by the source(s) of illumination, the scene itself, the medium through which the sensor is viewing the scene, the sensor system, or electronic circuits between the detector array and the processing system if they are to be useful for development and analysis of image processing (and machine vision) systems. Recent developments have led to the use of laser sensors for various machine vision applications including collision avoidance, wire detection and avoidance, intrusion detection, and underwater imaging systems. With recent developments in low cost laser systems, the use of these sensors for numerous applications relating to machine vision is likely to continue to expand for the foreseeable future. SPARTA's work in the area of image synthesis began with the development of a coherent laser radar simulation running on IBM and compatible personal computers, and has since branched into modeling of incoherent active and passive systems as well. SPARTA's current optical imaging sensor simulation, SENSORSIM, is written in ANSI standard FORTRAN '77 to ensure portability.

  3. Biomedical image processing

    SciTech Connect

    Huang, H.K.

    1981-01-01

    Biomedical image processing is a very broad field; it covers biomedical signal gathering, image forming, picture processing, and image display to medical diagnosis based on features extracted from images. This article reviews this topic in both its fundamentals and applications. In its fundamentals, some basic image processing techniques including outlining, deblurring, noise cleaning, filtering, search, classical analysis and texture analysis have been reviewed together with examples. The state-of-the-art image processing systems have been introduced and discussed in two categories: general purpose image processing systems and image analyzers. In order for these systems to be effective for biomedical applications, special biomedical image processing languages have to be developed. The combination of both hardware and software leads to clinical imaging devices. Two different types of clinical imaging devices have been discussed. There are radiological imagings which include radiography, thermography, ultrasound, nuclear medicine and CT. Among these, thermography is the most noninvasive but is limited in application due to the low energy of its source. X-ray CT is excellent for static anatomical images and is moving toward the measurement of dynamic function, whereas nuclear imaging is moving toward organ metabolism and ultrasound is toward tissue physical characteristics. Heart imaging is one of the most interesting and challenging research topics in biomedical image processing; current methods including the invasive-technique cineangiography, and noninvasive ultrasound, nuclear medicine, transmission, and emission CT methodologies have been reviewed.

  4. LandsatLook images

    USGS Publications Warehouse

    Jonescheit, Linda

    2011-01-01

    LandsatLook images are full resolution JPEG files derived from Landsat Level 1 data products. The images are compressed and stretched to create an image optimized for image selection and visual interpretation; it is not recommended that they be used in digital analysis.

  5. Adolescence and Body Image.

    ERIC Educational Resources Information Center

    Weinshenker, Naomi

    2002-01-01

    Discusses body image among adolescents, explaining that today's adolescents are more prone to body image distortions and dissatisfaction than ever and examining the historical context; how self-image develops; normative discontent; body image distortions; body dysmorphic disorder (BDD); vulnerability of boys (muscle dysmorphia); who is at risk;…

  6. Comparative cardiac imaging

    SciTech Connect

    Brundage, B.H.

    1990-01-01

    This book is designed to compare all major cardiac imaging techniques. All major imaging techniques - including conventional angiography, digital angiography, echocardiography and Doppler imaging, conventional radioisotope techniques, computed tomography, and magnetic resonance imaging - are covered in this text as they apply to the major cardiovascular disorders. There is brief coverage of positron emission tomography and an extensive presentation of ultrafast computed tomography.

  7. Image-Processing Educator

    NASA Technical Reports Server (NTRS)

    Gunther, F. J.

    1986-01-01

    Apple Image-Processing Educator (AIPE) explores ability of microcomputers to provide personalized computer-assisted instruction (CAI) in digital image processing of remotely sensed images. AIPE is "proof-of-concept" system, not polished production system. User-friendly prompts provide access to explanations of common features of digital image processing and of sample programs that implement these features.

  8. Seismic Imaging and Monitoring

    SciTech Connect

    Huang, Lianjie

    2012-07-09

    I give an overview of LANL's capability in seismic imaging and monitoring. I present some seismic imaging and monitoring results, including imaging of complex structures, subsalt imaging of Gulf of Mexico, fault/fracture zone imaging for geothermal exploration at the Jemez pueblo, time-lapse imaging of a walkway vertical seismic profiling data for monitoring CO{sub 2} inject at SACROC, and microseismic event locations for monitoring CO{sub 2} injection at Aneth. These examples demonstrate LANL's high-resolution and high-fidelity seismic imaging and monitoring capabilities.

  9. Intravascular Photoacoustic Imaging

    PubMed Central

    Wang, Bo; Su, Jimmy L.; Karpiouk, Andrei B.; Sokolov, Konstantin V.; Smalling, Richard W.; Emelianov, Stanislav Y.

    2011-01-01

    Intravascular photoacoustic (IVPA) imaging is a catheter-based, minimally invasive, imaging modality capable of providing high-resolution optical absorption map of the arterial wall. Integrated with intravascular ultrasound (IVUS) imaging, combined IVPA and IVUS imaging can be used to detect and characterize atherosclerotic plaques building up in the inner lining of an artery. In this paper, we present and discuss various representative applications of combined IVPA/IVUS imaging of atherosclerosis, including assessment of the composition of atherosclerotic plaques, imaging of macrophages within the plaques, and molecular imaging of biomarkers associated with formation and development of plaques. In addition, imaging of coronary artery stents using IVPA and IVUS imaging is demonstrated. Furthermore, the design of an integrated IVUS/IVPA imaging catheter needed for in vivo clinical applications is discussed. PMID:21359138

  10. Image Processing Software

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The Ames digital image velocimetry technology has been incorporated in a commercially available image processing software package that allows motion measurement of images on a PC alone. The software, manufactured by Werner Frei Associates, is IMAGELAB FFT. IMAGELAB FFT is a general purpose image processing system with a variety of other applications, among them image enhancement of fingerprints and use by banks and law enforcement agencies for analysis of videos run during robberies.

  11. Ultrasound Imaging System Video

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this video, astronaut Peggy Whitson uses the Human Research Facility (HRF) Ultrasound Imaging System in the Destiny Laboratory of the International Space Station (ISS) to image her own heart. The Ultrasound Imaging System provides three-dimension image enlargement of the heart and other organs, muscles, and blood vessels. It is capable of high resolution imaging in a wide range of applications, both research and diagnostic, such as Echocardiography (ultrasound of the heart), abdominal, vascular, gynecological, muscle, tendon, and transcranial ultrasound.

  12. Image Enhancement, Image Quality, and Noise

    NASA Technical Reports Server (NTRS)

    Rahman, Zia-ur; Jobson, Daniel J.; Woodell, Glenn A.; Hines, Glenn D.

    2005-01-01

    The Multiscale Retinex With Color Restoration (MSRCR) is a non-linear image enhancement algorithm that provides simultaneous dynamic range compression, color constancy and rendition. The overall impact is to brighten up areas of poor contrast/lightness but not at the expense of saturating areas of good contrast/brightness. The downside is that with the poor signal-to-noise ratio that most image acquisition devices have in dark regions, noise can also be greatly enhanced thus affecting overall image quality. In this paper, we will discuss the impact of the MSRCR on the overall quality of an enhanced image as a function of the strength of shadows in an image, and as a function of the root-mean-square (RMS) signal-to-noise (SNR) ratio of the image.

  13. Lymphatic Imaging: Focus on Imaging Probes

    PubMed Central

    Niu, Gang; Chen, Xiaoyuan

    2015-01-01

    In view of the importance of sentinel lymph nodes (SLNs) in tumor staging and patient management, sensitive and accurate imaging of SLNs has been intensively explored. Along with the advance of the imaging technology, various contrast agents have been developed for lymphatic imaging. In this review, the lymph node imaging agents were summarized into three groups: tumor targeting agents, lymphatic targeting agents and lymphatic mapping agents. Tumor targeting agents are used to detect metastatic tumor tissue within LNs, lymphatic targeting agents aim to visualize lymphatic vessels and lymphangionesis, while lymphatic mapping agents are mainly for SLN detection during surgery after local administration. Coupled with various signal emitters, these imaging agents work with single or multiple imaging modalities to provide a valuable way to evaluate the location and metastatic status of SLNs. PMID:25897334

  14. Image based performance analysis of thermal imagers

    NASA Astrophysics Data System (ADS)

    Wegner, D.; Repasi, E.

    2016-05-01

    Due to advances in technology, modern thermal imagers resemble sophisticated image processing systems in functionality. Advanced signal and image processing tools enclosed into the camera body extend the basic image capturing capability of thermal cameras. This happens in order to enhance the display presentation of the captured scene or specific scene details. Usually, the implemented methods are proprietary company expertise, distributed without extensive documentation. This makes the comparison of thermal imagers especially from different companies a difficult task (or at least a very time consuming/expensive task - e.g. requiring the execution of a field trial and/or an observer trial). For example, a thermal camera equipped with turbulence mitigation capability stands for such a closed system. The Fraunhofer IOSB has started to build up a system for testing thermal imagers by image based methods in the lab environment. This will extend our capability of measuring the classical IR-system parameters (e.g. MTF, MTDP, etc.) in the lab. The system is set up around the IR- scene projector, which is necessary for the thermal display (projection) of an image sequence for the IR-camera under test. The same set of thermal test sequences might be presented to every unit under test. For turbulence mitigation tests, this could be e.g. the same turbulence sequence. During system tests, gradual variation of input parameters (e. g. thermal contrast) can be applied. First ideas of test scenes selection and how to assembly an imaging suite (a set of image sequences) for the analysis of imaging thermal systems containing such black boxes in the image forming path is discussed.

  15. Image registration method for medical image sequences

    DOEpatents

    Gee, Timothy F.; Goddard, James S.

    2013-03-26

    Image registration of low contrast image sequences is provided. In one aspect, a desired region of an image is automatically segmented and only the desired region is registered. Active contours and adaptive thresholding of intensity or edge information may be used to segment the desired regions. A transform function is defined to register the segmented region, and sub-pixel information may be determined using one or more interpolation methods.

  16. Parallel MR Imaging

    PubMed Central

    Deshmane, Anagha; Gulani, Vikas; Griswold, Mark A.; Seiberlich, Nicole

    2015-01-01

    Parallel imaging is a robust method for accelerating the acquisition of magnetic resonance imaging (MRI) data, and has made possible many new applications of MR imaging. Parallel imaging works by acquiring a reduced amount of k-space data with an array of receiver coils. These undersampled data can be acquired more quickly, but the undersampling leads to aliased images. One of several parallel imaging algorithms can then be used to reconstruct artifact-free images from either the aliased images (SENSE-type reconstruction) or from the under-sampled data (GRAPPA-type reconstruction). The advantages of parallel imaging in a clinical setting include faster image acquisition, which can be used, for instance, to shorten breath-hold times resulting in fewer motion-corrupted examinations. In this article the basic concepts behind parallel imaging are introduced. The relationship between undersampling and aliasing is discussed and two commonly used parallel imaging methods, SENSE and GRAPPA, are explained in detail. Examples of artifacts arising from parallel imaging are shown and ways to detect and mitigate these artifacts are described. Finally, several current applications of parallel imaging are presented and recent advancements and promising research in parallel imaging are briefly reviewed. PMID:22696125

  17. Optical image encryption based on diffractive imaging.

    PubMed

    Chen, Wen; Chen, Xudong; Sheppard, Colin J R

    2010-11-15

    In this Letter, we propose a method for optical image encryption based on diffractive imaging. An optical multiple random phase mask encoding system is applied, and one of the phase-only masks is selected and laterally translated along a preset direction during the encryption process. For image decryption, a phase retrieval algorithm is proposed to extract a high-quality plaintext. The feasibility and effectiveness of the proposed method are demonstrated by numerical results. The proposed method can provide a new strategy instead of conventional interference methods, and it may open up a new research perspective for optical image encryption.

  18. Fast image decompression for telebrowsing of images

    NASA Technical Reports Server (NTRS)

    Miaou, Shaou-Gang; Tou, Julius T.

    1993-01-01

    Progressive image transmission (PIT) is often used to reduce the transmission time of an image telebrowsing system. A side effect of the PIT is the increase of computational complexity at the viewer's site. This effect is more serious in transform domain techniques than in other techniques. Recent attempts to reduce the side effect are futile as they create another side effect, namely, the discontinuous and unpleasant image build-up. Based on a practical assumption that image blocks to be inverse transformed are generally sparse, this paper presents a method to minimize both side effects simultaneously.

  19. Multispectral imaging for biometrics

    NASA Astrophysics Data System (ADS)

    Rowe, Robert K.; Corcoran, Stephen P.; Nixon, Kristin A.; Ostrom, Robert E.

    2005-03-01

    Automated identification systems based on fingerprint images are subject to two significant types of error: an incorrect decision about the identity of a person due to a poor quality fingerprint image and incorrectly accepting a fingerprint image generated from an artificial sample or altered finger. This paper discusses the use of multispectral sensing as a means to collect additional information about a finger that significantly augments the information collected using a conventional fingerprint imager based on total internal reflectance. In the context of this paper, "multispectral sensing" is used broadly to denote a collection of images taken under different polarization conditions and illumination configurations, as well as using multiple wavelengths. Background information is provided on conventional fingerprint imaging. A multispectral imager for fingerprint imaging is then described and a means to combine the two imaging systems into a single unit is discussed. Results from an early-stage prototype of such a system are shown.

  20. Future generation CT imaging.

    PubMed

    Walter, Deborah; De Man, Bruno; Iatrou, Maria; Edic, Peter M

    2004-02-01

    X-ray CT technology has been available for more than 30 years, yet continued technological advances have kept CT imaging at the forefront of medical imaging innovation. Consequently, the number of clinical CT applications has increased steadily. Other imaging modalities might be superior to CT imaging for some specific applications, but no other single modality is more often used in chest imaging today. Future technological developments in the area of high-resolution detectors, high-capacity x-ray tubes, advanced reconstruction algorithms, and improved visualization techniques will continue to expand the imaging capability. Future CT imaging technology will combine improved imaging capability with advanced and specific computer-assisted tools, which will expand the usefulness of CT imaging in many areas.

  1. Subroutines For Image Processing

    NASA Technical Reports Server (NTRS)

    Faulcon, Nettie D.; Monteith, James H.; Miller, Keith W.

    1988-01-01

    Image Processing Library computer program, IPLIB, is collection of subroutines facilitating use of COMTAL image-processing system driven by HP 1000 computer. Functions include addition or subtraction of two images with or without scaling, display of color or monochrome images, digitization of image from television camera, display of test pattern, manipulation of bits, and clearing of screen. Provides capability to read or write points, lines, and pixels from image; read or write at location of cursor; and read or write array of integers into COMTAL memory. Written in FORTRAN 77.

  2. Imager for Mars Pathfinder (IMP) image calibration

    USGS Publications Warehouse

    Reid, R.J.; Smith, P.H.; Lemmon, M.; Tanner, R.; Burkland, M.; Wegryn, E.; Weinberg, J.; Marcialis, R.; Britt, D.T.; Thomas, N.; Kramm, R.; Dummel, A.; Crowe, D.; Bos, B.J.; Bell, J.F.; Rueffer, P.; Gliem, F.; Johnson, J. R.; Maki, J.N.; Herkenhoff, K. E.; Singer, Robert B.

    1999-01-01

    The Imager for Mars Pathfinder returned over 16,000 high-quality images from the surface of Mars. The camera was well-calibrated in the laboratory, with <5% radiometric uncertainty. The photometric properties of two radiometric targets were also measured with 3% uncertainty. Several data sets acquired during the cruise and on Mars confirm that the system operated nominally throughout the course of the mission. Image calibration algorithms were developed for landed operations to correct instrumental sources of noise and to calibrate images relative to observations of the radiometric targets. The uncertainties associated with these algorithms as well as current improvements to image calibration are discussed. Copyright 1999 by the American Geophysical Union.

  3. A hyperspectral image projector for hyperspectral imagers

    NASA Astrophysics Data System (ADS)

    Rice, Joseph P.; Brown, Steven W.; Neira, Jorge E.; Bousquet, Robert R.

    2007-04-01

    We have developed and demonstrated a Hyperspectral Image Projector (HIP) intended for system-level validation testing of hyperspectral imagers, including the instrument and any associated spectral unmixing algorithms. HIP, based on the same digital micromirror arrays used in commercial digital light processing (DLP*) displays, is capable of projecting any combination of many different arbitrarily programmable basis spectra into each image pixel at up to video frame rates. We use a scheme whereby one micromirror array is used to produce light having the spectra of endmembers (i.e. vegetation, water, minerals, etc.), and a second micromirror array, optically in series with the first, projects any combination of these arbitrarily-programmable spectra into the pixels of a 1024 x 768 element spatial image, thereby producing temporally-integrated images having spectrally mixed pixels. HIP goes beyond conventional DLP projectors in that each spatial pixel can have an arbitrary spectrum, not just arbitrary color. As such, the resulting spectral and spatial content of the projected image can simulate realistic scenes that a hyperspectral imager will measure during its use. Also, the spectral radiance of the projected scenes can be measured with a calibrated spectroradiometer, such that the spectral radiance projected into each pixel of the hyperspectral imager can be accurately known. Use of such projected scenes in a controlled laboratory setting would alleviate expensive field testing of instruments, allow better separation of environmental effects from instrument effects, and enable system-level performance testing and validation of hyperspectral imagers as used with analysis algorithms. For example, known mixtures of relevant endmember spectra could be projected into arbitrary spatial pixels in a hyperspectral imager, enabling tests of how well a full system, consisting of the instrument + calibration + analysis algorithm, performs in unmixing (i.e. de-convolving) the

  4. Simpler images, better results

    NASA Astrophysics Data System (ADS)

    Chance, Britton

    1999-03-01

    The very rapid development of optical technology has followed a pattern similar to that of nuclear magnetic resonance: first, spectroscopy and then imaging. The accomplishments in spectroscopy have been significant--among them, early detection of hematomas and quantitative oximetry (assuming that time and frequency domain instruments are used). Imaging has progressed somewhat later. The first images were obtained in Japan and USA a few years ago, particularly of parietal stimulation of the human brain. Since then, rapid applications to breast and limb, together with higher resolution of the brain now make NIR imaging of functional activation and tumor detection readily available, reliable and affordable devices. The lecture has to do with the applications of imaging to these three areas, particularly to prefrontal imaging of cognitive function, of breast tumor detection, and of localized muscle activation in exercise. The imaging resolution achievable in functional activation appears to be FWHM of 4 mm. The time required for an image is a few seconds or even much less. Breast image detection at 50 microsecond(s) ec/pixel results in images obtainable in a few seconds or shorter times (bandwidths of the kHz are available). Finally, imaging of the body organs is under study in this laboratory, particularly in the in utero fetus. It appears that the photon migration theory now leads to the development of a wide number of images for human subject tissue spectroscopy and imaging.

  5. Photoacoustic imaging in biomedicine

    NASA Astrophysics Data System (ADS)

    Xu, Minghua; Wang, Lihong V.

    2006-04-01

    Photoacoustic imaging (also called optoacoustic or thermoacoustic imaging) has the potential to image animal or human organs, such as the breast and the brain, with simultaneous high contrast and high spatial resolution. This article provides an overview of the rapidly expanding field of photoacoustic imaging for biomedical applications. Imaging techniques, including depth profiling in layered media, scanning tomography with focused ultrasonic transducers, image forming with an acoustic lens, and computed tomography with unfocused transducers, are introduced. Special emphasis is placed on computed tomography, including reconstruction algorithms, spatial resolution, and related recent experiments. Promising biomedical applications are discussed throughout the text, including (1) tomographic imaging of the skin and other superficial organs by laser-induced photoacoustic microscopy, which offers the critical advantages, over current high-resolution optical imaging modalities, of deeper imaging depth and higher absorption contrasts, (2) breast cancer detection by near-infrared light or radio-frequency-wave-induced photoacoustic imaging, which has important potential for early detection, and (3) small animal imaging by laser-induced photoacoustic imaging, which measures unique optical absorption contrasts related to important biochemical information and provides better resolution in deep tissues than optical imaging.

  6. Hepatitis B virus (image)

    MedlinePlus

    Hepatitis B is also known as serum hepatitis and is spread through blood and sexual contact. It is ... population. This photograph is an electronmicroscopic image of hepatitis B virus particles. (Image courtesy of the Centers for ...

  7. The Power of Images

    ERIC Educational Resources Information Center

    Sherman, Vivian

    1977-01-01

    The role played by images in the course of human development is considered in this article; personal growth is defined at three different levels of imagery: the producer/consumer image, the humanistic, and the transpersonal. (JD)

  8. Weighted guided image filtering.

    PubMed

    Li, Zhengguo; Zheng, Jinghong; Zhu, Zijian; Yao, Wei; Wu, Shiqian

    2015-01-01

    It is known that local filtering-based edge preserving smoothing techniques suffer from halo artifacts. In this paper, a weighted guided image filter (WGIF) is introduced by incorporating an edge-aware weighting into an existing guided image filter (GIF) to address the problem. The WGIF inherits advantages of both global and local smoothing filters in the sense that: 1) the complexity of the WGIF is O(N) for an image with N pixels, which is same as the GIF and 2) the WGIF can avoid halo artifacts like the existing global smoothing filters. The WGIF is applied for single image detail enhancement, single image haze removal, and fusion of differently exposed images. Experimental results show that the resultant algorithms produce images with better visual quality and at the same time halo artifacts can be reduced/avoided from appearing in the final images with negligible increment on running times. PMID:25415986

  9. Preclinical lymphatic imaging.

    PubMed

    Zhang, Fan; Niu, Gang; Lu, Guangming; Chen, Xiaoyuan

    2011-08-01

    Noninvasive in vivo imaging of lymphatic vessels and lymphatic nodes is expected to fulfill the purpose of analyzing lymphatic vessels and their function, understanding molecular mechanisms of lymphangiogenesis and lymphatic spread of tumors, and utilizing lymphatic molecular markers as a prognostic or diagnostic indicator. In this review, we provide a comprehensive summary of in vivo imaging modalities for detecting lymphatic vessels, lymphatic drainage, and lymphatic nodes, which include conventional lymphatic imaging techniques such as dyes and radionuclide scintigraphy as well as novel techniques for lymphatic imaging such as optical imaging, computed tomography, magnetic resonance imaging, ultrasound, positron emission tomography using lymphatic biomarkers, photoacoustic imaging, and combinations of multiple modalities. The field of lymphatic imaging is ever evolving, and technological advances, combined with the development of new contrast agents, continue to improve the research of lymphatic vascular system in health and disease states as well as to improve the accuracy of diagnosis in the relevant diseases.

  10. Multi Spectral Imaging System

    NASA Technical Reports Server (NTRS)

    Spiering, Bruce A. (Inventor)

    1999-01-01

    An optical imaging system provides automatic co-registration of a plurality of multi spectral images of an object which are generated by a plurality of video cameras or other optical detectors. The imaging system includes a modular assembly of beam splitters, lens tubes, camera lenses and wavelength selective filters which facilitate easy reconfiguration and adjustment of the system for various applications. A primary lens assembly generates a real image of an object to be imaged on a reticle which is positioned at a fixed length from a beam splitter assembly. The beam splitter assembly separates a collimated image beam received from the reticle into multiple image beams, each of which is projected onto a corresponding one of a plurality of video cameras. The lens tubes which connect the beam splitter assembly to the cameras are adjustable in length to provide automatic co-registration of the images generated by each camera.

  11. Image tools for UNIX

    NASA Technical Reports Server (NTRS)

    Banks, David C.

    1994-01-01

    This talk features two simple and useful tools for digital image processing in the UNIX environment. They are xv and pbmplus. The xv image viewer which runs under the X window system reads images in a number of different file formats and writes them out in different formats. The view area supports a pop-up control panel. The 'algorithms' menu lets you blur an image. The xv control panel also activates the color editor which displays the image's color map (if one exists). The xv image viewer is available through the internet. The pbmplus package is a set of tools designed to perform image processing from within a UNIX shell. The acronym 'pbm' stands for portable bit map. Like xv, the pbm plus tool can convert images from and to many different file formats. The source code and manual pages for pbmplus are also available through the internet. This software is in the public domain.

  12. Medical Image Databases

    PubMed Central

    Tagare, Hemant D.; Jaffe, C. Carl; Duncan, James

    1997-01-01

    Abstract Information contained in medical images differs considerably from that residing in alphanumeric format. The difference can be attributed to four characteristics: (1) the semantics of medical knowledge extractable from images is imprecise; (2) image information contains form and spatial data, which are not expressible in conventional language; (3) a large part of image information is geometric; (4) diagnostic inferences derived from images rest on an incomplete, continuously evolving model of normality. This paper explores the differentiating characteristics of text versus images and their impact on design of a medical image database intended to allow content-based indexing and retrieval. One strategy for implementing medical image databases is presented, which employs object-oriented iconic queries, semantics by association with prototypes, and a generic schema. PMID:9147338

  13. Aerial Image Systems

    NASA Astrophysics Data System (ADS)

    Clapp, Robert E.

    1987-09-01

    Aerial images produce the best stereoscopic images of the viewed world. Despite the fact that every optic in existence produces an aerial image, few persons are aware of their existence and possible uses. Constant reference to the eye and other optical systems have produced a psychosis of design that only considers "focal planes" in the design and analysis of optical systems. All objects in the field of view of the optical device are imaged by the device as an aerial image. Use of aerial images in vision and visual display systems can provide a true stereoscopic representation of the viewed world. This paper discusses aerial image systems - their applications and designs and presents designs and design concepts that utilize aerial images to obtain superior visual displays, particularly with application to visual simulation.

  14. Preclinical Lymphatic Imaging

    PubMed Central

    Zhang, Fan; Niu, Gang; Lu, Guangming; Chen, Xiaoyuan

    2011-01-01

    Non-invasive in vivo imaging of lymphatic vessels and lymphatic nodes is expected to fulfill the purpose of analyzing lymphatic vessels and their function, understanding molecular mechanisms of lymphangiogenesis and lymphatic spread of tumors, and utilizing lymphatic molecular markers as a prognostic or diagnostic indicator. In this review, we provide a comprehensive summary of in vivo imaging modalities for detecting lymphatic vessels, lymphatic drainage, lymphatic nodes, which include conventional lymphatic imaging techniques such as dyes and radionuclide scintigraphy as well as novel techniques for lymphatic imaging such as optical imaging, computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET) using lymphatic biomarkers, photoacoustic imaging and combinations of multiple modalities. The field of lymphatic imaging is ever evolving, and technological advances, combined with the development of new contrast agents, continue to improve the research of lymphatic vascular system in health and disease states as well as to improve the accuracy of diagnosis in the relevant diseases. PMID:20862613

  15. Overview of Imaging Tests

    MedlinePlus

    ... Mentioned In This Article Medical Dictionary Also of Interest (Quiz) Magnetic Resonance Imaging (MRI) (Video) Ear Pressure ... Tap here for the Professional Version Also of Interest Test your knowledge Magnetic resonance imaging (MRI) is ...

  16. Spectrographic imaging system

    DOEpatents

    Morris, Michael D.; Treado, Patrick J.

    1991-01-01

    An imaging system for providing spectrographically resolved images. The system incorporates a one-dimensional spatial encoding mask which enables an image to be projected onto a two-dimensional image detector after spectral dispersion of the image. The dimension of the image which is lost due to spectral dispersion on the two-dimensional detector is recovered through employing a reverse transform based on presenting a multiplicity of different spatial encoding patterns to the image. The system is especially adapted for detecting Raman scattering of monochromatic light transmitted through or reflected from physical samples. Preferably, spatial encoding is achieved through the use of Hadamard mask which selectively transmits or blocks portions of the image from the sample being evaluated.

  17. Video image position determination

    DOEpatents

    Christensen, Wynn; Anderson, Forrest L.; Kortegaard, Birchard L.

    1991-01-01

    An optical beam position controller in which a video camera captures an image of the beam in its video frames, and conveys those images to a processing board which calculates the centroid coordinates for the image. The image coordinates are used by motor controllers and stepper motors to position the beam in a predetermined alignment. In one embodiment, system noise, used in conjunction with Bernoulli trials, yields higher resolution centroid coordinates.

  18. Biomedical photoacoustic imaging

    PubMed Central

    Beard, Paul

    2011-01-01

    Photoacoustic (PA) imaging, also called optoacoustic imaging, is a new biomedical imaging modality based on the use of laser-generated ultrasound that has emerged over the last decade. It is a hybrid modality, combining the high-contrast and spectroscopic-based specificity of optical imaging with the high spatial resolution of ultrasound imaging. In essence, a PA image can be regarded as an ultrasound image in which the contrast depends not on the mechanical and elastic properties of the tissue, but its optical properties, specifically optical absorption. As a consequence, it offers greater specificity than conventional ultrasound imaging with the ability to detect haemoglobin, lipids, water and other light-absorbing chomophores, but with greater penetration depth than purely optical imaging modalities that rely on ballistic photons. As well as visualizing anatomical structures such as the microvasculature, it can also provide functional information in the form of blood oxygenation, blood flow and temperature. All of this can be achieved over a wide range of length scales from micrometres to centimetres with scalable spatial resolution. These attributes lend PA imaging to a wide variety of applications in clinical medicine, preclinical research and basic biology for studying cancer, cardiovascular disease, abnormalities of the microcirculation and other conditions. With the emergence of a variety of truly compelling in vivo images obtained by a number of groups around the world in the last 2–3 years, the technique has come of age and the promise of PA imaging is now beginning to be realized. Recent highlights include the demonstration of whole-body small-animal imaging, the first demonstrations of molecular imaging, the introduction of new microscopy modes and the first steps towards clinical breast imaging being taken as well as a myriad of in vivo preclinical imaging studies. In this article, the underlying physical principles of the technique, its practical

  19. Image quality analyzer

    NASA Astrophysics Data System (ADS)

    Lukin, V. P.; Botugina, N. N.; Emaleev, O. N.; Antoshkin, L. V.; Konyaev, P. A.

    2012-07-01

    Image quality analyzer (IQA) which used as device for efficiency analysis of adaptive optics application is described. In analyzer marketed possibility estimations quality of images on three different criterions of quality images: contrast, sharpnesses and the spectral criterion. At present given analyzer is introduced on Big Solar Vacuum Telescope in stale work that allows at observations to conduct the choice of the most contrasting images of Sun. Is it hereinafter planned use the analyzer in composition of the ANGARA adaptive correction system.

  20. Biomedical photoacoustic imaging.

    PubMed

    Beard, Paul

    2011-08-01

    Photoacoustic (PA) imaging, also called optoacoustic imaging, is a new biomedical imaging modality based on the use of laser-generated ultrasound that has emerged over the last decade. It is a hybrid modality, combining the high-contrast and spectroscopic-based specificity of optical imaging with the high spatial resolution of ultrasound imaging. In essence, a PA image can be regarded as an ultrasound image in which the contrast depends not on the mechanical and elastic properties of the tissue, but its optical properties, specifically optical absorption. As a consequence, it offers greater specificity than conventional ultrasound imaging with the ability to detect haemoglobin, lipids, water and other light-absorbing chomophores, but with greater penetration depth than purely optical imaging modalities that rely on ballistic photons. As well as visualizing anatomical structures such as the microvasculature, it can also provide functional information in the form of blood oxygenation, blood flow and temperature. All of this can be achieved over a wide range of length scales from micrometres to centimetres with scalable spatial resolution. These attributes lend PA imaging to a wide variety of applications in clinical medicine, preclinical research and basic biology for studying cancer, cardiovascular disease, abnormalities of the microcirculation and other conditions. With the emergence of a variety of truly compelling in vivo images obtained by a number of groups around the world in the last 2-3 years, the technique has come of age and the promise of PA imaging is now beginning to be realized. Recent highlights include the demonstration of whole-body small-animal imaging, the first demonstrations of molecular imaging, the introduction of new microscopy modes and the first steps towards clinical breast imaging being taken as well as a myriad of in vivo preclinical imaging studies. In this article, the underlying physical principles of the technique, its practical

  1. Coherent imaging at FLASH

    NASA Astrophysics Data System (ADS)

    Chapman, H. N.; Bajt, S.; Barty, A.; Benner, W. H.; Bogan, M. J.; Boutet, S.; Cavalleri, A.; Duesterer, S.; Frank, M.; Hajdu, J.; Hau-Riege, S. P.; Iwan, B.; Marchesini, S.; Sakdinawat, A.; Sokolowski-Tinten, K.; Seibert, M. M.; Timneanu, N.; Treusch, R.; Woods, B. W.

    2009-09-01

    We have carried out high-resolution single-pulse coherent diffractive imaging at the FLASH free-electron laser. The intense focused FEL pulse gives a high-resolution low-noise coherent diffraction pattern of an object before that object turns into a plasma and explodes. In particular we are developing imaging of biological specimens beyond conventional radiation damage resolution limits, developing imaging of ultrafast processes, and testing methods to characterize and perform single-particle imaging.

  2. High compression image and image sequence coding

    NASA Technical Reports Server (NTRS)

    Kunt, Murat

    1989-01-01

    The digital representation of an image requires a very large number of bits. This number is even larger for an image sequence. The goal of image coding is to reduce this number, as much as possible, and reconstruct a faithful duplicate of the original picture or image sequence. Early efforts in image coding, solely guided by information theory, led to a plethora of methods. The compression ratio reached a plateau around 10:1 a couple of years ago. Recent progress in the study of the brain mechanism of vision and scene analysis has opened new vistas in picture coding. Directional sensitivity of the neurones in the visual pathway combined with the separate processing of contours and textures has led to a new class of coding methods capable of achieving compression ratios as high as 100:1 for images and around 300:1 for image sequences. Recent progress on some of the main avenues of object-based methods is presented. These second generation techniques make use of contour-texture modeling, new results in neurophysiology and psychophysics and scene analysis.

  3. Image quality (IQ) guided multispectral image compression

    NASA Astrophysics Data System (ADS)

    Zheng, Yufeng; Chen, Genshe; Wang, Zhonghai; Blasch, Erik

    2016-05-01

    Image compression is necessary for data transportation, which saves both transferring time and storage space. In this paper, we focus on our discussion on lossy compression. There are many standard image formats and corresponding compression algorithms, for examples, JPEG (DCT -- discrete cosine transform), JPEG 2000 (DWT -- discrete wavelet transform), BPG (better portable graphics) and TIFF (LZW -- Lempel-Ziv-Welch). The image quality (IQ) of decompressed image will be measured by numerical metrics such as root mean square error (RMSE), peak signal-to-noise ratio (PSNR), and structural Similarity (SSIM) Index. Given an image and a specified IQ, we will investigate how to select a compression method and its parameters to achieve an expected compression. Our scenario consists of 3 steps. The first step is to compress a set of interested images by varying parameters and compute their IQs for each compression method. The second step is to create several regression models per compression method after analyzing the IQ-measurement versus compression-parameter from a number of compressed images. The third step is to compress the given image with the specified IQ using the selected compression method (JPEG, JPEG2000, BPG, or TIFF) according to the regressed models. The IQ may be specified by a compression ratio (e.g., 100), then we will select the compression method of the highest IQ (SSIM, or PSNR). Or the IQ may be specified by a IQ metric (e.g., SSIM = 0.8, or PSNR = 50), then we will select the compression method of the highest compression ratio. Our experiments tested on thermal (long-wave infrared) images (in gray scales) showed very promising results.

  4. Nursing's Image on Campus.

    ERIC Educational Resources Information Center

    Woolley, Alma S.

    1981-01-01

    In studying the nurse's image at a liberal arts college, it was found that faculty and administrators view nurses as long-suffering drones. On the whole, the image of nursing was positive, with those who had the most contact with the nursing program having a more enlightened image. (CT)

  5. XVD Image Display Program

    NASA Technical Reports Server (NTRS)

    Deen, Robert G.; Andres, Paul M.; Mortensen, Helen B.; Parizher, Vadim; McAuley, Myche; Bartholomew, Paul

    2009-01-01

    The XVD [X-Windows VICAR (video image communication and retrieval) Display] computer program offers an interactive display of VICAR and PDS (planetary data systems) images. It is designed to efficiently display multiple-GB images and runs on Solaris, Linux, or Mac OS X systems using X-Windows.

  6. Medical imaging systems

    SciTech Connect

    Frangioni, John V

    2013-06-25

    A medical imaging system provides simultaneous rendering of visible light and diagnostic or functional images. The system may be portable, and may include adapters for connecting various light sources and cameras in open surgical environments or laparascopic or endoscopic environments. A user interface provides control over the functionality of the integrated imaging system. In one embodiment, the system provides a tool for surgical pathology.

  7. Whole animal imaging

    PubMed Central

    Sandhu, Gurpreet Singh; Solorio, Luis; Broome, Ann-Marie; Salem, Nicolas; Kolthammer, Jeff; Shah, Tejas; Flask, Chris; Duerk, Jeffrey L.

    2015-01-01

    Translational research plays a vital role in understanding the underlying pathophysiology of human diseases, and hence development of new diagnostic and therapeutic options for their management. After creating an animal disease model, pathophysiologic changes and effects of a therapeutic intervention on them are often evaluated on the animals using immunohistologic or imaging techniques. In contrast to the immunohistologic techniques, the imaging techniques are noninvasive and hence can be used to investigate the whole animal, oftentimes in a single exam which provides opportunities to perform longitudinal studies and dynamic imaging of the same subject, and hence minimizes the experimental variability, requirement for the number of animals, and the time to perform a given experiment. Whole animal imaging can be performed by a number of techniques including x-ray computed tomography, magnetic resonance imaging, ultrasound imaging, positron emission tomography, single photon emission computed tomography, fluorescence imaging, and bioluminescence imaging, among others. Individual imaging techniques provide different kinds of information regarding the structure, metabolism, and physiology of the animal. Each technique has its own strengths and weaknesses, and none serves every purpose of image acquisition from all regions of an animal. In this review, a broad overview of basic principles, available contrast mechanisms, applications, challenges, and future prospects of many imaging techniques employed for whole animal imaging is provided. Our main goal is to briefly describe the current state of art to researchers and advanced students with a strong background in the field of animal research. PMID:20836038

  8. Digital Imaging Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Bamberger, Casimir; Renz, Uwe; Bamberger, Andreas

    2011-06-01

    Methods to visualize the two-dimensional (2D) distribution of molecules by mass spectrometric imaging evolve rapidly and yield novel applications in biology, medicine, and material surface sciences. Most mass spectrometric imagers acquire high mass resolution spectra spot-by-spot and thereby scan the object's surface. Thus, imaging is slow and image reconstruction remains cumbersome. Here we describe an imaging mass spectrometer that exploits the true imaging capabilities by ion optical means for the time of flight mass separation. The mass spectrometer is equipped with the ASIC Timepix chip as an array detector to acquire the position, mass, and intensity of ions that are imaged by matrix-assisted laser desorption/ionization (MALDI) directly from the target sample onto the detector. This imaging mass spectrometer has a spatial resolving power at the specimen of (84 ± 35) μm with a mass resolution of 45 and locates atoms or organic compounds on a surface area up to ~2 cm2. Extended laser spots of ~5 mm2 on structured specimens allows parallel imaging of selected masses. The digital imaging mass spectrometer proves high hit-multiplicity, straightforward image reconstruction, and potential for high-speed readout at 4 kHz or more. This device demonstrates a simple way of true image acquisition like a digital photographic camera. The technology may enable a fast analysis of biomolecular samples in near future.

  9. 3D Imaging.

    ERIC Educational Resources Information Center

    Hastings, S. K.

    2002-01-01

    Discusses 3 D imaging as it relates to digital representations in virtual library collections. Highlights include X-ray computed tomography (X-ray CT); the National Science Foundation (NSF) Digital Library Initiatives; output peripherals; image retrieval systems, including metadata; and applications of 3 D imaging for libraries and museums. (LRW)

  10. Cancer imaging archive available

    Cancer.gov

    NCI’s Cancer Imaging Program has inaugurated The Cancer Imaging Archive (TCIA), a web-accessible and unique clinical imaging archive linked to The Cancer Genome Atlas (TCGA) tissue repository. It contains a large proportion of original, pre-surgical MRIs from cases that have been genomically characterized in TCGA.

  11. Image Acquisition Context

    PubMed Central

    Bidgood, W. Dean; Bray, Bruce; Brown, Nicolas; Mori, Angelo Rossi; Spackman, Kent A.; Golichowski, Alan; Jones, Robert H.; Korman, Louis; Dove, Brent; Hildebrand, Lloyd; Berg, Michael

    1999-01-01

    Objective: To support clinically relevant indexing of biomedical images and image-related information based on the attributes of image acquisition procedures and the judgments (observations) expressed by observers in the process of image interpretation. Design: The authors introduce the notion of “image acquisition context,” the set of attributes that describe image acquisition procedures, and present a standards-based strategy for utilizing the attributes of image acquisition context as indexing and retrieval keys for digital image libraries. Methods: The authors' indexing strategy is based on an interdependent message/terminology architecture that combines the Digital Imaging and Communication in Medicine (DICOM) standard, the SNOMED (Systematized Nomenclature of Human and Veterinary Medicine) vocabulary, and the SNOMED DICOM microglossary. The SNOMED DICOM microglossary provides context-dependent mapping of terminology to DICOM data elements. Results: The capability of embedding standard coded descriptors in DICOM image headers and image-interpretation reports improves the potential for selective retrieval of image-related information. This favorably affects information management in digital libraries. PMID:9925229

  12. Interpretation of Image Content.

    ERIC Educational Resources Information Center

    Pettersson, Rune

    1988-01-01

    Describes experiments and studies which investigated perception and image interpretation on different cognitive levels. Subjects were asked to name, describe, index, and assess image contents; write legends; create images; complete stories; illustrate stories; and produce informative materials. Results confirmed the theory of a dual stage…

  13. Intellectual Access to Images.

    ERIC Educational Resources Information Center

    Chen, Hsin-Liang; Rasmussen, Edie M.

    1999-01-01

    The increased availability of digital images is accompanied by a need for solutions to the problems inherent in indexing them for retrieval. Problems in image description and access are discussed, with a perspective on traditional and new solutions. Recent developments in intellectual access to images are surveyed and contrasted with…

  14. What Is Optical Imaging?

    ERIC Educational Resources Information Center

    Hespos, Susan J.

    2010-01-01

    This article introduces a promising new methodology called optical imaging. Optical imaging is used for measuring changes in cortical blood flow due to functional activation. The article outlines the pros and cons of using optical imaging for studying the brain correlates of perceptual, cognitive, and language development in infants and young…

  15. Displaying Images Of Planets

    NASA Technical Reports Server (NTRS)

    Martin, Michael D.; Evans, Frank; Nakamura, Daniel I.

    1991-01-01

    Interactive Image Display Program (IMDISP) is interactive image-displaying utility program for IBM personal computer (PC, XT, and AT models) and compatibles. Magnifications, contrasts, and/or subsampling selected for whole or partial images. IMDISP developed for use with CD-ROM (Compact Disk Read-Only Memory) storage system. Written in C language (94 percent) and Assembler (6 percent).

  16. Hyperspectral image processing methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hyperspectral image processing refers to the use of computer algorithms to extract, store and manipulate both spatial and spectral information contained in hyperspectral images across the visible and near-infrared portion of the electromagnetic spectrum. A typical hyperspectral image processing work...

  17. Methods in Astronomical Image Processing

    NASA Astrophysics Data System (ADS)

    Jörsäter, S.

    A Brief Introductory Note History of Astronomical Imaging Astronomical Image Data Images in Various Formats Digitized Image Data Digital Image Data Philosophy of Astronomical Image Processing Properties of Digital Astronomical Images Human Image Processing Astronomical vs. Computer Science Image Processing Basic Tools of Astronomical Image Processing Display Applications Calibration of Intensity Scales Calibration of Length Scales Image Re-shaping Feature Enhancement Noise Suppression Noise and Error Analysis Image Processing Packages: Design of AIPS and MIDAS AIPS MIDAS Reduction of CCD Data Bias Subtraction Clipping Preflash Subtraction Dark Subtraction Flat Fielding Sky Subtraction Extinction Correction Deconvolution Methods Rebinning/Combining Summary and Prospects for the Future

  18. SWNT Imaging Using Multispectral Image Processing

    NASA Astrophysics Data System (ADS)

    Blades, Michael; Pirbhai, Massooma; Rotkin, Slava V.

    2012-02-01

    A flexible optical system was developed to image carbon single-wall nanotube (SWNT) photoluminescence using the multispectral capabilities of a typical CCD camcorder. The built in Bayer filter of the CCD camera was utilized, using OpenCV C++ libraries for image processing, to decompose the image generated in a high magnification epifluorescence microscope setup into three pseudo-color channels. By carefully calibrating the filter beforehand, it was possible to extract spectral data from these channels, and effectively isolate the SWNT signals from the background.

  19. An image processing algorithm for PPCR imaging

    NASA Astrophysics Data System (ADS)

    Cowen, Arnold R.; Giles, Anthony; Davies, Andrew G.; Workman, A.

    1993-09-01

    During 1990 The UK Department of Health installed two Photostimulable Phosphor Computed Radiography (PPCR) systems in the General Infirmary at Leeds with a view to evaluating the clinical and physical performance of the technology prior to its introduction into the NHS. An issue that came to light from the outset of the projects was the radiologists reservations about the influence of the standard PPCR computerized image processing on image quality and diagnostic performance. An investigation was set up by FAXIL to develop an algorithm to produce single format high quality PPCR images that would be easy to implement and allay the concerns of radiologists.

  20. Medical image file formats.

    PubMed

    Larobina, Michele; Murino, Loredana

    2014-04-01

    Image file format is often a confusing aspect for someone wishing to process medical images. This article presents a demystifying overview of the major file formats currently used in medical imaging: Analyze, Neuroimaging Informatics Technology Initiative (Nifti), Minc, and Digital Imaging and Communications in Medicine (Dicom). Concepts common to all file formats, such as pixel depth, photometric interpretation, metadata, and pixel data, are first presented. Then, the characteristics and strengths of the various formats are discussed. The review concludes with some predictive considerations about the future trends in medical image file formats.

  1. Future Imaging Sensor Capabilities

    NASA Technical Reports Server (NTRS)

    Carver, K. R.; Ando, K. J.

    1983-01-01

    Advanced imaging sensor technologies that are being developed for future NASA earth observation missions are discussed. These include the multilinear array, the Shuttle imaging spectrometer, and the Shuttle imaging radar. The principal specifications and functional descriptions of the instruments are presented, and it is shown that the advanced technologies will enable a synergistic approach to the use of VIS/IR and microwave imaging sensors for remote sensing research and applications. The key problems posed by these future imaging sensor technologies are discussed, with particular attention given to data rates, power consumption, and data processing.

  2. Imaging of the cerebrum.

    PubMed

    Kim, Paul E; Zee, Chi Shing

    2007-07-01

    The history of the development of cerebral imaging is a complex combination of the forces of innovation at both the individual and industrial levels. Principal paradigms of neuroimaging shifted as a result of technological breakthroughs, beginning with the discovery of x-rays and continuing with the development of computerized imaging to the latest imaging paradigm, nuclear magnetic resonance imaging. We discuss these landmarks in neuroimaging in historical context, with emphasis on the particularly rapid development of imaging technology during the past 30 to 40 years, including the most recent emerging technologies.

  3. Imaging of pericardial disease.

    PubMed

    Glockner, James F

    2003-02-01

    Pericardial pathology is most often identified by its effect on cardiac function. Echocardiography is usually performed first in evaluation of pericardial disease, but is occasionally limited or indeterminate. MR imaging is often helpful in these cases, offering superior soft tissue contrast and the ability to image the entire pericardium and its relationship to cardiac structure and function. Many of the techniques recently developed for myocardial imaging are equally applicable to the pericardium and frequently assist in the diagnosis of pericardial disease. In this article, the authors review MR imaging techniques for pericardial imaging, discuss the appearance of the normal pericardium, and illustrate pathologic and congenital conditions of the pericardium.

  4. Medical image file formats.

    PubMed

    Larobina, Michele; Murino, Loredana

    2014-04-01

    Image file format is often a confusing aspect for someone wishing to process medical images. This article presents a demystifying overview of the major file formats currently used in medical imaging: Analyze, Neuroimaging Informatics Technology Initiative (Nifti), Minc, and Digital Imaging and Communications in Medicine (Dicom). Concepts common to all file formats, such as pixel depth, photometric interpretation, metadata, and pixel data, are first presented. Then, the characteristics and strengths of the various formats are discussed. The review concludes with some predictive considerations about the future trends in medical image file formats. PMID:24338090

  5. Sinusoidal ghost imaging.

    PubMed

    Khamoushi, S M Mahdi; Nosrati, Yaser; Tavassoli, S Hassan

    2015-08-01

    We introduce sinusoidal ghost imaging (SGI), which uses 2D orthogonal sinusoidal patterns instead of random patterns in "computational ghost imaging" (CGI). Simulations and experiments are performed. In comparison with the"differential ghost imaging" algorithm that was used to improve the SNR of ghost imaging, results of SGI show about 3 orders of magnitude higher SNR, which can be reconstructed even with a much smaller number of patterns. More importantly, based on the results, SGI provides the great opportunity to generate innate processed images by predefined selection of patterns. This can speed up detection process considerably and paves the way for real applications. PMID:26258330

  6. Fourier plane imaging microscopy

    SciTech Connect

    Dominguez, Daniel Peralta, Luis Grave de; Alharbi, Nouf; Alhusain, Mdhaoui; Bernussi, Ayrton A.

    2014-09-14

    We show how the image of an unresolved photonic crystal can be reconstructed using a single Fourier plane (FP) image obtained with a second camera that was added to a traditional compound microscope. We discuss how Fourier plane imaging microscopy is an application of a remarkable property of the obtained FP images: they contain more information about the photonic crystals than the images recorded by the camera commonly placed at the real plane of the microscope. We argue that the experimental results support the hypothesis that surface waves, contributing to enhanced resolution abilities, were optically excited in the studied photonic crystals.

  7. Correlation Plenoptic Imaging.

    PubMed

    D'Angelo, Milena; Pepe, Francesco V; Garuccio, Augusto; Scarcelli, Giuliano

    2016-06-01

    Plenoptic imaging is a promising optical modality that simultaneously captures the location and the propagation direction of light in order to enable three-dimensional imaging in a single shot. However, in standard plenoptic imaging systems, the maximum spatial and angular resolutions are fundamentally linked; thereby, the maximum achievable depth of field is inversely proportional to the spatial resolution. We propose to take advantage of the second-order correlation properties of light to overcome this fundamental limitation. In this Letter, we demonstrate that the correlation in both momentum and position of chaotic light leads to the enhanced refocusing power of correlation plenoptic imaging with respect to standard plenoptic imaging. PMID:27314718

  8. Correlation Plenoptic Imaging.

    PubMed

    D'Angelo, Milena; Pepe, Francesco V; Garuccio, Augusto; Scarcelli, Giuliano

    2016-06-01

    Plenoptic imaging is a promising optical modality that simultaneously captures the location and the propagation direction of light in order to enable three-dimensional imaging in a single shot. However, in standard plenoptic imaging systems, the maximum spatial and angular resolutions are fundamentally linked; thereby, the maximum achievable depth of field is inversely proportional to the spatial resolution. We propose to take advantage of the second-order correlation properties of light to overcome this fundamental limitation. In this Letter, we demonstrate that the correlation in both momentum and position of chaotic light leads to the enhanced refocusing power of correlation plenoptic imaging with respect to standard plenoptic imaging.

  9. Hip Imaging in Athletes: Sports Imaging Series.

    PubMed

    Agten, Christoph A; Sutter, Reto; Buck, Florian M; Pfirrmann, Christian W A

    2016-08-01

    Hip or groin pain in athletes is common and clinical presentation is often nonspecific. Imaging is a very important diagnostic step in the work-up of athletes with hip pain. This review article provides an overview on hip biomechanics and discusses strategies for hip imaging modalities such as radiography, ultrasonography, computed tomography, and magnetic resonance (MR) imaging (MR arthrography and traction MR arthrography). The authors explain current concepts of femoroacetabular impingement and the problem of high prevalence of cam- and pincer-type morphology in asymptomatic persons. With the main focus on MR imaging, the authors present abnormalities of the hip joint and the surrounding soft tissues that can occur in athletes: intraarticular and extraarticular hip impingement syndromes, labral and cartilage disease, microinstability of the hip, myotendinous injuries, and athletic pubalgia. (©) RSNA, 2016. PMID:27429142

  10. Annotating images by mining image search results.

    PubMed

    Wang, Xin-Jing; Zhang, Lei; Li, Xirong; Ma, Wei-Ying

    2008-11-01

    Although it has been studied for years by the computer vision and machine learning communities, image annotation is still far from practical. In this paper, we propose a novel attempt at model-free image annotation, which is a data-driven approach that annotates images by mining their search results. Some 2.4 million images with their surrounding text are collected from a few photo forums to support this approach. The entire process is formulated in a divide-and-conquer framework where a query keyword is provided along with the uncaptioned image to improve both the effectiveness and efficiency. This is helpful when the collected data set is not dense everywhere. In this sense, our approach contains three steps: 1) the search process to discover visually and semantically similar search results, 2) the mining process to identify salient terms from textual descriptions of the search results, and 3) the annotation rejection process to filter out noisy terms yielded by Step 2. To ensure real-time annotation, two key techniques are leveraged-one is to map the high-dimensional image visual features into hash codes, the other is to implement it as a distributed system, of which the search and mining processes are provided as Web services. As a typical result, the entire process finishes in less than 1 second. Since no training data set is required, our approach enables annotating with unlimited vocabulary and is highly scalable and robust to outliers. Experimental results on both real Web images and a benchmark image data set show the effectiveness and efficiency of the proposed algorithm. It is also worth noting that, although the entire approach is illustrated within the divide-and conquer framework, a query keyword is not crucial to our current implementation. We provide experimental results to prove this.

  11. Lensless Imaging and Sensing.

    PubMed

    Ozcan, Aydogan; McLeod, Euan

    2016-07-11

    High-resolution optical microscopy has traditionally relied on high-magnification and high-numerical aperture objective lenses. In contrast, lensless microscopy can provide high-resolution images without the use of any focusing lenses, offering the advantages of a large field of view, high resolution, cost-effectiveness, portability, and depth-resolved three-dimensional (3D) imaging. Here we review various approaches to lensless imaging, as well as its applications in biosensing, diagnostics, and cytometry. These approaches include shadow imaging, fluorescence, holography, superresolution 3D imaging, iterative phase recovery, and color imaging. These approaches share a reliance on computational techniques, which are typically necessary to reconstruct meaningful images from the raw data captured by digital image sensors. When these approaches are combined with physical innovations in sample preparation and fabrication, lensless imaging can be used to image and sense cells, viruses, nanoparticles, and biomolecules. We conclude by discussing several ways in which lensless imaging and sensing might develop in the near future. PMID:27420569

  12. Lensless Imaging and Sensing.

    PubMed

    Ozcan, Aydogan; McLeod, Euan

    2016-07-11

    High-resolution optical microscopy has traditionally relied on high-magnification and high-numerical aperture objective lenses. In contrast, lensless microscopy can provide high-resolution images without the use of any focusing lenses, offering the advantages of a large field of view, high resolution, cost-effectiveness, portability, and depth-resolved three-dimensional (3D) imaging. Here we review various approaches to lensless imaging, as well as its applications in biosensing, diagnostics, and cytometry. These approaches include shadow imaging, fluorescence, holography, superresolution 3D imaging, iterative phase recovery, and color imaging. These approaches share a reliance on computational techniques, which are typically necessary to reconstruct meaningful images from the raw data captured by digital image sensors. When these approaches are combined with physical innovations in sample preparation and fabrication, lensless imaging can be used to image and sense cells, viruses, nanoparticles, and biomolecules. We conclude by discussing several ways in which lensless imaging and sensing might develop in the near future.

  13. GOATS Image Projection Component

    NASA Technical Reports Server (NTRS)

    Haber, Benjamin M.; Green, Joseph J.

    2011-01-01

    When doing mission analysis and design of an imaging system in orbit around the Earth, answering the fundamental question of imaging performance requires an understanding of the image products that will be produced by the imaging system. GOATS software represents a series of MATLAB functions to provide for geometric image projections. Unique features of the software include function modularity, a standard MATLAB interface, easy-to-understand first-principles-based analysis, and the ability to perform geometric image projections of framing type imaging systems. The software modules are created for maximum analysis utility, and can all be used independently for many varied analysis tasks, or used in conjunction with other orbit analysis tools.

  14. Functions of images

    NASA Astrophysics Data System (ADS)

    Lehtonen, Juha; Andriyashin, Alexey; Parkkinen, Jussi; Leisti, Tuomas; Nyman, Göte

    2006-10-01

    The visual quality of images is outward in image presentation, compression and analysis. Depending on the use, the quality of images may give more information or more experiences to the viewer. However, the relations between mathematical and human methods for grouping the images are not obvious. For example, different humans think differently and so, they make the grouping differently. However, there may be some connections between image mathematical features and human selections. Here we try to find such relations that could give more possibilities for developing the actual quality of images for different purposes. In this study, we present some methods and preliminary results that are based on psychological tests to humans, MPEG-7 based features of the images and face detection methods. We also show some notes and questions belonging to this problem and plans for the future research.

  15. Compressive Optical Image Encryption

    PubMed Central

    Li, Jun; Sheng Li, Jiao; Yang Pan, Yang; Li, Rong

    2015-01-01

    An optical image encryption technique based on compressive sensing using fully optical means has been proposed. An object image is first encrypted to a white-sense stationary noise pattern using a double random phase encoding (DRPE) method in a Mach-Zehnder interferometer. Then, the encrypted image is highly compressed to a signal using single-pixel compressive holographic imaging in the optical domain. At the receiving terminal, the encrypted image is reconstructed well via compressive sensing theory, and the original image can be decrypted with three reconstructed holograms and the correct keys. The numerical simulations show that the method is effective and suitable for optical image security transmission in future all-optical networks because of the ability of completely optical implementation and substantially smaller hologram data volume. PMID:25992946

  16. Speckle imaging of satellites

    SciTech Connect

    Fitch, J.P.; Lawrence, T.W.; Goodman, D.M.; Johansson, E.M.

    1991-12-01

    We performed a series of experiments using the Air Force Optical Station`s 1.6 m telescope and a bare CCD detector to capture speckle images of various satellites. The speckle images were processed with bispectral techniques for recovering image Fourier phase as well as projection onto convex sets for recovering image Fourier magnitude from the projected autocorrelation. Results of imaging point stars and binaries are shown as a baseline assessment of our technique. We have reconstructed high quality images of numerous satellites and will show reconstructions of a very familiar satellite: the Hubble Space Telescope. To our knowledge, this is the first demonstration of the use of bare CCDs for speckle imaging of relatively bright objects such as artificial satellites. 8 refs.

  17. Speckle imaging of satellites

    SciTech Connect

    Fitch, J.P.; Lawrence, T.W.; Goodman, D.M.; Johansson, E.M.

    1991-12-01

    We performed a series of experiments using the Air Force Optical Station's 1.6 m telescope and a bare CCD detector to capture speckle images of various satellites. The speckle images were processed with bispectral techniques for recovering image Fourier phase as well as projection onto convex sets for recovering image Fourier magnitude from the projected autocorrelation. Results of imaging point stars and binaries are shown as a baseline assessment of our technique. We have reconstructed high quality images of numerous satellites and will show reconstructions of a very familiar satellite: the Hubble Space Telescope. To our knowledge, this is the first demonstration of the use of bare CCDs for speckle imaging of relatively bright objects such as artificial satellites. 8 refs.

  18. Compressive Optical Image Encryption

    NASA Astrophysics Data System (ADS)

    Li, Jun; Sheng Li, Jiao; Yang Pan, Yang; Li, Rong

    2015-05-01

    An optical image encryption technique based on compressive sensing using fully optical means has been proposed. An object image is first encrypted to a white-sense stationary noise pattern using a double random phase encoding (DRPE) method in a Mach-Zehnder interferometer. Then, the encrypted image is highly compressed to a signal using single-pixel compressive holographic imaging in the optical domain. At the receiving terminal, the encrypted image is reconstructed well via compressive sensing theory, and the original image can be decrypted with three reconstructed holograms and the correct keys. The numerical simulations show that the method is effective and suitable for optical image security transmission in future all-optical networks because of the ability of completely optical implementation and substantially smaller hologram data volume.

  19. First-photon imaging.

    PubMed

    Kirmani, Ahmed; Venkatraman, Dheera; Shin, Dongeek; Colaço, Andrea; Wong, Franco N C; Shapiro, Jeffrey H; Goyal, Vivek K

    2014-01-01

    Imagers that use their own illumination can capture three-dimensional (3D) structure and reflectivity information. With photon-counting detectors, images can be acquired at extremely low photon fluxes. To suppress the Poisson noise inherent in low-flux operation, such imagers typically require hundreds of detected photons per pixel for accurate range and reflectivity determination. We introduce a low-flux imaging technique, called first-photon imaging, which is a computational imager that exploits spatial correlations found in real-world scenes and the physics of low-flux measurements. Our technique recovers 3D structure and reflectivity from the first detected photon at each pixel. We demonstrate simultaneous acquisition of sub-pulse duration range and 4-bit reflectivity information in the presence of high background noise. First-photon imaging may be of considerable value to both microscopy and remote sensing.

  20. Applications of Molecular Imaging

    PubMed Central

    Galbán, Craig; Galbán, Stefanie; Van Dort, Marcian; Luker, Gary D.; Bhojani, Mahaveer S.; Rehemtualla, Alnawaz; Ross, Brian D.

    2015-01-01

    Today molecular imaging technologies play a central role in clinical oncology. The use of imaging techniques in early cancer detection, treatment response and new therapy development is steadily growing and has already significantly impacted clinical management of cancer. In this chapter we will overview three different molecular imaging technologies used for the understanding of disease biomarkers, drug development, or monitoring therapeutic outcome. They are (1) optical imaging (bioluminescence and fluorescence imaging) (2) magnetic resonance imaging (MRI), and (3) nuclear imaging (e.g, single photon emission computed tomography (SPECT) and positron emission tomography (PET)). We will review the use of molecular reporters of biological processes (e.g. apoptosis and protein kinase activity) for high throughput drug screening and new cancer therapies, diffusion MRI as a biomarker for early treatment response and PET and SPECT radioligands in oncology. PMID:21075334

  1. Portable Imaging Polarimeter and Imaging Experiments

    SciTech Connect

    PHIPPS,GARY S.; KEMME,SHANALYN A.; SWEATT,WILLIAM C.; DESCOUR,M.R.; GARCIA,J.P.; DERENIAK,E.L.

    1999-11-01

    Polarimetry is the method of recording the state of polarization of light. Imaging polarimetry extends this method to recording the spatially resolved state of polarization within a scene. Imaging-polarimetry data have the potential to improve the detection of manmade objects in natural backgrounds. We have constructed a midwave infrared complete imaging polarimeter consisting of a fixed wire-grid polarizer and rotating form-birefringent retarder. The retardance and the orientation angles of the retarder were optimized to minimize the sensitivity of the instrument to noise in the measurements. The optimal retardance was found to be 132{degree} rather than the typical 90{degree}. The complete imaging polarimeter utilized a liquid-nitrogen cooled PtSi camera. The fixed wire-grid polarizer was located at the cold stop inside the camera dewar. The complete imaging polarimeter was operated in the 4.42-5 {micro}m spectral range. A series of imaging experiments was performed using as targets a surface of water, an automobile, and an aircraft. Further analysis of the polarization measurements revealed that in all three cases the magnitude of circular polarization was comparable to the noise in the calculated Stokes-vector components.

  2. Uncooled thermal imaging and image analysis

    NASA Astrophysics Data System (ADS)

    Wang, Shiyun; Chang, Benkang; Yu, Chunyu; Zhang, Junju; Sun, Lianjun

    2006-09-01

    Thermal imager can transfer difference of temperature to difference of electric signal level, so can be application to medical treatment such as estimation of blood flow speed and vessel 1ocation [1], assess pain [2] and so on. With the technology of un-cooled focal plane array (UFPA) is grown up more and more, some simple medical function can be completed with un-cooled thermal imager, for example, quick warning for fever heat with SARS. It is required that performance of imaging is stabilization and spatial and temperature resolution is high enough. In all performance parameters, noise equivalent temperature difference (NETD) is often used as the criterion of universal performance. 320 x 240 α-Si micro-bolometer UFPA has been applied widely presently for its steady performance and sensitive responsibility. In this paper, NETD of UFPA and the relation between NETD and temperature are researched. several vital parameters that can affect NETD are listed and an universal formula is presented. Last, the images from the kind of thermal imager are analyzed based on the purpose of detection persons with fever heat. An applied thermal image intensification method is introduced.

  3. Medical Imaging: A Review

    NASA Astrophysics Data System (ADS)

    Ganguly, Debashis; Chakraborty, Srabonti; Balitanas, Maricel; Kim, Tai-Hoon

    The rapid progress of medical science and the invention of various medicines have benefited mankind and the whole civilization. Modern science also has been doing wonders in the surgical field. But, the proper and correct diagnosis of diseases is the primary necessity before the treatment. The more sophisticate the bio-instruments are, better diagnosis will be possible. The medical images plays an important role in clinical diagnosis and therapy of doctor and teaching and researching etc. Medical imaging is often thought of as a way to represent anatomical structures of the body with the help of X-ray computed tomography and magnetic resonance imaging. But often it is more useful for physiologic function rather than anatomy. With the growth of computer and image technology medical imaging has greatly influenced medical field. As the quality of medical imaging affects diagnosis the medical image processing has become a hotspot and the clinical applications wanting to store and retrieve images for future purpose needs some convenient process to store those images in details. This paper is a tutorial review of the medical image processing and repository techniques appeared in the literature.

  4. Image compression technique

    DOEpatents

    Fu, C.Y.; Petrich, L.I.

    1997-03-25

    An image is compressed by identifying edge pixels of the image; creating a filled edge array of pixels each of the pixels in the filled edge array which corresponds to an edge pixel having a value equal to the value of a pixel of the image array selected in response to the edge pixel, and each of the pixels in the filled edge array which does not correspond to an edge pixel having a value which is a weighted average of the values of surrounding pixels in the filled edge array which do correspond to edge pixels; and subtracting the filled edge array from the image array to create a difference array. The edge file and the difference array are then separately compressed and transmitted or stored. The original image is later reconstructed by creating a preliminary array in response to the received edge file, and adding the preliminary array to the received difference array. Filling is accomplished by solving Laplace`s equation using a multi-grid technique. Contour and difference file coding techniques also are described. The techniques can be used in a method for processing a plurality of images by selecting a respective compression approach for each image, compressing each of the images according to the compression approach selected, and transmitting each of the images as compressed, in correspondence with an indication of the approach selected for the image. 16 figs.

  5. Image compression technique

    DOEpatents

    Fu, Chi-Yung; Petrich, Loren I.

    1997-01-01

    An image is compressed by identifying edge pixels of the image; creating a filled edge array of pixels each of the pixels in the filled edge array which corresponds to an edge pixel having a value equal to the value of a pixel of the image array selected in response to the edge pixel, and each of the pixels in the filled edge array which does not correspond to an edge pixel having a value which is a weighted average of the values of surrounding pixels in the filled edge array which do correspond to edge pixels; and subtracting the filled edge array from the image array to create a difference array. The edge file and the difference array are then separately compressed and transmitted or stored. The original image is later reconstructed by creating a preliminary array in response to the received edge file, and adding the preliminary array to the received difference array. Filling is accomplished by solving Laplace's equation using a multi-grid technique. Contour and difference file coding techniques also are described. The techniques can be used in a method for processing a plurality of images by selecting a respective compression approach for each image, compressing each of the images according to the compression approach selected, and transmitting each of the images as compressed, in correspondence with an indication of the approach selected for the image.

  6. Medical image processing system

    NASA Astrophysics Data System (ADS)

    Wang, Dezong; Wang, Jinxiang

    1994-12-01

    In this paper a medical image processing system is described. That system is named NAI200 Medical Image Processing System and has been appraised by Chinese Government. Principles and cases provided here. Many kinds of pictures are used in modern medical diagnoses, for example B-supersonic, X-ray, CT and MRI. Some times the pictures are not good enough for diagnoses. The noises interfere with real situation on these pictures. That means the image processing is needed. A medical image processing system is described in this paper. That system is named NAI200 Medical Image Processing System and has been appraised by Chinese Government. There are four functions in that system. The first part is image processing. More than thirty four programs are involved. The second part is calculating. The areas or volumes of single or multitissues are calculated. Three dimensional reconstruction is the third part. The stereo images of organs or tumors are reconstructed with cross-sections. The last part is image storage. All pictures can be transformed to digital images, then be stored in hard disk or soft disk. In this paper not only all functions of that system are introduced, also the basic principles of these functions are explained in detail. This system has been applied in hospitals. The images of hundreds of cases have been processed. We describe the functions combining real cases. Here we only introduce a few examples.

  7. Image processing in medicine

    NASA Astrophysics Data System (ADS)

    Dallas, William J.; Roehrig, Hans

    2001-12-01

    This article is divided into two parts: the first is an opinion, the second is a description. The opinion is that diagnostic medical imaging is not a detection problem. The description is of a specific medical image-processing program. Why the opinion? If medical imaging were a detection problem, then image processing would unimportant. However, image processing is crucial. We illustrate this fact using three examples ultrasound, magnetic resonance imaging and, most poignantly, computed radiography. Although the examples are anecdotal they are illustrative. The description is of the image-processing program ImprocRAD written by one of the authors (Dallas). First we will discuss the motivation for creating yet another image processing program including system characterization which is an area of expertise of one of the authors (Roehrig). We will then look at the structure of the program and finally, to the point, the specific application: mammographic diagnostic reading. We will mention rapid display of mammogram image sets and then discuss processing. In that context, we describe a real-time image-processing tool we term the MammoGlass.

  8. Introduction to computer image processing

    NASA Technical Reports Server (NTRS)

    Moik, J. G.

    1973-01-01

    Theoretical backgrounds and digital techniques for a class of image processing problems are presented. Image formation in the context of linear system theory, image evaluation, noise characteristics, mathematical operations on image and their implementation are discussed. Various techniques for image restoration and image enhancement are presented. Methods for object extraction and the problem of pictorial pattern recognition and classification are discussed.

  9. Computation in electron microscopy.

    PubMed

    Kirkland, Earl J

    2016-01-01

    Some uses of the computer and computation in high-resolution transmission electron microscopy are reviewed. The theory of image calculation using Bloch wave and multislice methods with and without aberration correction is reviewed and some applications are discussed. The inverse problem of reconstructing the specimen structure from an experimentally measured electron microscope image is discussed. Some future directions of software development are given. PMID:26697863

  10. Synthetic Foveal Imaging Technology

    NASA Technical Reports Server (NTRS)

    Hoenk, Michael; Monacos, Steve; Nikzad, Shouleh

    2009-01-01

    Synthetic Foveal imaging Technology (SyFT) is an emerging discipline of image capture and image-data processing that offers the prospect of greatly increased capabilities for real-time processing of large, high-resolution images (including mosaic images) for such purposes as automated recognition and tracking of moving objects of interest. SyFT offers a solution to the image-data processing problem arising from the proposed development of gigapixel mosaic focal-plane image-detector assemblies for very wide field-of-view imaging with high resolution for detecting and tracking sparse objects or events within narrow subfields of view. In order to identify and track the objects or events without the means of dynamic adaptation to be afforded by SyFT, it would be necessary to post-process data from an image-data space consisting of terabytes of data. Such post-processing would be time-consuming and, as a consequence, could result in missing significant events that could not be observed at all due to the time evolution of such events or could not be observed at required levels of fidelity without such real-time adaptations as adjusting focal-plane operating conditions or aiming of the focal plane in different directions to track such events. The basic concept of foveal imaging is straightforward: In imitation of a natural eye, a foveal-vision image sensor is designed to offer higher resolution in a small region of interest (ROI) within its field of view. Foveal vision reduces the amount of unwanted information that must be transferred from the image sensor to external image-data-processing circuitry. The aforementioned basic concept is not new in itself: indeed, image sensors based on these concepts have been described in several previous NASA Tech Briefs articles. Active-pixel integrated-circuit image sensors that can be programmed in real time to effect foveal artificial vision on demand are one such example. What is new in SyFT is a synergistic combination of recent

  11. The NITRC image repository.

    PubMed

    Kennedy, David N; Haselgrove, Christian; Riehl, Jon; Preuss, Nina; Buccigrossi, Robert

    2016-01-01

    The Neuroimaging Informatics Tools and Resources Clearinghouse (NITRC - www.nitrc.org) suite of services include a resources registry, image repository and a cloud computational environment to meet the needs of the neuroimaging researcher. NITRC provides image-sharing functionality through both the NITRC Resource Registry (NITRC-R), where bulk data files can be released through the file release system (FRS), and the NITRC Image Repository (NITRC-IR), a XNAT-based image data management system. Currently hosting 14 projects, 6845 subjects, and 8285 MRI imaging sessions, NITRC-IR provides a large array of structural, diffusion and resting state MRI data. Designed to be flexible about management of data access policy, NITRC provides a simple, free, NIH-funded service to support resource sharing in general, and image sharing in particular. PMID:26044860

  12. Spectral ensemble ghost imaging

    NASA Astrophysics Data System (ADS)

    Jha, Nandan

    2015-07-01

    In the last few years, the field of ghost imaging has seen many new developments. From computational ghost imaging to 3D gh.ost imaging, this field has shown many interesting applications. But the method of obtaining an image in ghost imaging experiments still requires data to be recorded over a long duration of time due to averaging over many shots of data. We propose a method to get the intensity correlated images in one shot by averaging over different wavelength components rather than different time components. We derive the maximum number of wavelength components that can be used for a given multi-wavelength source. The applicability of this scheme is finally verified by numerical simulations.

  13. Radiation imaging system

    DOEpatents

    Immel, David M.; Bobbit, III, John T.; Plummer, Jean R.; Folsom, Matthew D.; Serrato, Michael G.

    2016-03-22

    A radiation imaging system includes a casing and a camera disposed inside the casing. A first field of view through the casing exposes the camera to light from outside of the casing. An image plate is disposed inside the casing, and a second field of view through the casing to the image plate exposes the image plate to high-energy particles produced by a radioisotope outside of the casing. An optical reflector that is substantially transparent to the high-energy particles produced by the radioisotope is disposed with respect to the camera and the image plate to reflect light to the camera and to allow the high-energy particles produced by the radioisotope to pass through the optical reflector to the image plate.

  14. Radiation imaging system

    DOEpatents

    Bobbitt, III, John T.; Immel, David M.; Folsom, Matthew D.; Plummer, Jean R.; Serrato, Michael G.

    2016-06-28

    A radiation imaging system includes a casing and a camera disposed inside the casing. A first field of view through the casing exposes the camera to light from outside of the casing. An image plate is disposed inside the casing, and a second field of view through the casing to the image plate exposes the image plate to high-energy particles produced by a radioisotope outside of the casing. An optical reflector that is substantially transparent to the high-energy particles produced by the radioisotope is disposed with respect to the camera and the image plate to reflect light to the camera and to allow the high-energy particles produced by the radioisotope to pass through the optical reflector to the image plate.

  15. Integrated Dual Imaging Detector

    NASA Technical Reports Server (NTRS)

    Rust, David M.

    1999-01-01

    A new type of image detector was designed to simultaneously analyze the polarization of light at all picture elements in a scene. The integrated Dual Imaging detector (IDID) consists of a lenslet array and a polarizing beamsplitter bonded to a commercial charge coupled device (CCD). The IDID simplifies the design and operation of solar vector magnetographs and the imaging polarimeters and spectroscopic imagers used, for example, in atmosphere and solar research. When used in a solar telescope, the vector magnetic fields on the solar surface. Other applications include environmental monitoring, robot vision, and medical diagnoses (through the eye). Innovations in the IDID include (1) two interleaved imaging arrays (one for each polarization plane); (2) large dynamic range (well depth of 10(exp 5) electrons per pixel); (3) simultaneous readout and display of both images; and (4) laptop computer signal processing to produce polarization maps in field situations.

  16. BAOlab: Image processing program

    NASA Astrophysics Data System (ADS)

    Larsen, Søren S.

    2014-03-01

    BAOlab is an image processing package written in C that should run on nearly any UNIX system with just the standard C libraries. It reads and writes images in standard FITS format; 16- and 32-bit integer as well as 32-bit floating-point formats are supported. Multi-extension FITS files are currently not supported. Among its tools are ishape for size measurements of compact sources, mksynth for generating synthetic images consisting of a background signal including Poisson noise and a number of pointlike sources, imconvol for convolving two images (a “source” and a “kernel”) with each other using fast fourier transforms (FFTs) and storing the output as a new image, and kfit2d for fitting a two-dimensional King model to an image.

  17. Imaging arrangement and microscope

    SciTech Connect

    Pertsinidis, Alexandros; Chu, Steven

    2015-12-15

    An embodiment of the present invention is an imaging arrangement that includes imaging optics, a fiducial light source, and a control system. In operation, the imaging optics separate light into first and second tight by wavelength and project the first and second light onto first and second areas within first and second detector regions, respectively. The imaging optics separate fiducial light from the fiducial light source into first and second fiducial light and project the first and second fiducial light onto third and fourth areas within the first and second detector regions, respectively. The control system adjusts alignment of the imaging optics so that the first and second fiducial light projected onto the first and second detector regions maintain relatively constant positions within the first and second detector regions, respectively. Another embodiment of the present invention is a microscope that includes the imaging arrangement.

  18. Synthetic Foveal Imaging Technology

    NASA Technical Reports Server (NTRS)

    Monacos, Steve P. (Inventor); Hoenk, Michael E. (Inventor); Nikzad, Shouleh (Inventor)

    2013-01-01

    Apparatuses and methods are disclosed that create a synthetic fovea in order to identify and highlight interesting portions of an image for further processing and rapid response. Synthetic foveal imaging implements a parallel processing architecture that uses reprogrammable logic to implement embedded, distributed, real-time foveal image processing from different sensor types while simultaneously allowing for lossless storage and retrieval of raw image data. Real-time, distributed, adaptive processing of multi-tap image sensors with coordinated processing hardware used for each output tap is enabled. In mosaic focal planes, a parallel-processing network can be implemented that treats the mosaic focal plane as a single ensemble rather than a set of isolated sensors. Various applications are enabled for imaging and robotic vision where processing and responding to enormous amounts of data quickly and efficiently is important.

  19. [Clinical imaging in psychiatry].

    PubMed

    Jabourian, A P; Benhamou, P A; Bitton, R

    1996-01-01

    Brain imaging has made surprisingly remarkable progress since the early, and now historic days, of invasive radiology, which has now been replaced with a number of spectacularly precise techniques: structural (CT Scan, MRI) and functional (PET, SPECT) imaging, direct imaging during neurosurgery, EEG and its computer-assisted derivatives, and transcerebral ultrasonography. We present five cases with two alleged autisms, a cerebral malaria, a panic disorder and to Parkinson disease with a depressive component. Using modern imaging methods the following respective diagnoses were arrived at: a left temporal cyst, a Sanfilippo mucopolysaccharidosis, a septum lucidum agenesis, a right temporal cyst, and a pituitary adenoma. These cases illustrate the scientific, emotional and philosophical impact, on physicians, and patients alike, of modern imaging technology. Neuroradiology, biochemistry and surgical imaging require a multi disciplinary approach and a perfect knowledge of psychiatric semeiology. In addition, they stimulate us to carefully reassess our sociocultural understanding to mental illness.

  20. Imaging beyond the proteome

    PubMed Central

    Chang, Pamela V.; Bertozzi, Carolyn R.

    2013-01-01

    Imaging technologies developed in the early 20th century achieved contrast solely by relying on macroscopic and morphological differences between the tissues of interest and the surrounding tissues. Since then, there has been a movement toward imaging at the cellular and molecular level in order to visualize biological processes. This rapidly growing field is known as molecular imaging. In the last decade, many methodologies for imaging proteins have emerged. However, most of these approaches cannot be extended to imaging beyond the proteome. Here, we highlight some of the recently developed technologies that enable imaging of non-proteinaceous molecules in the cell: lipids, signalling molecules, inorganic ions, glycans, nucleic acids, small-molecule metabolites, and protein post-translational modifications such as phosphorylation and methylation. PMID:22801420

  1. Imaging interferometric microscopy.

    PubMed

    Schwarz, Christian J; Kuznetsova, Yuliya; Brueck, S R J

    2003-08-15

    We introduce and demonstrate a new microscopy concept: imaging interferometric microscopy (IIM), which is related to holography, synthetic-aperture imaging, and off-axis-dark-field illumination techniques. IIM is a wavelength-division multiplex approach to image formation that combines multiple images covering different spatial-frequency regions to form a composite image with a resolution much greater than that permitted by the same optical system using conventional techniques. This new type of microscopy involves both off-axis coherent illumination and reinjection of appropriate zero-order reference beams. Images demonstrate high resolution, comparable with that of a high-numerical-aperture (NA) objective, while they retain the long working distance, the large depth of field, and the large field of view of a low-NA objective. A Fourier-optics model of IIM is in good agreement with the experiment. PMID:12943079

  2. imageMCR

    2011-09-27

    imageMCR is a user friendly software package that consists of a variety inputs to preprocess and analyze the hyperspectral image data using multivariate algorithms such as Multivariate Curve Resolution (MCR), Principle Component Analysis (PCA), Classical Least Squares (CLS) and Parallel Factor Analysis (PARAFAC). MCR provides a relative quantitative analysis of the hyperspectral image data without the need for standards, and it discovers all the emitting species (spectral pure components) present in an image, even thosemore » in which there is no a priori information. Once the spectral components are discovered, these spectral components can be used for future MCR analyses or used with CLS algorithms to quickly extract concentration image maps for each component within spectral image data sets.« less

  3. Video Toroid Cavity Imager

    DOEpatents

    Gerald, II, Rex E.; Sanchez, Jairo; Rathke, Jerome W.

    2004-08-10

    A video toroid cavity imager for in situ measurement of electrochemical properties of an electrolytic material sample includes a cylindrical toroid cavity resonator containing the sample and employs NMR and video imaging for providing high-resolution spectral and visual information of molecular characteristics of the sample on a real-time basis. A large magnetic field is applied to the sample under controlled temperature and pressure conditions to simultaneously provide NMR spectroscopy and video imaging capabilities for investigating electrochemical transformations of materials or the evolution of long-range molecular aggregation during cooling of hydrocarbon melts. The video toroid cavity imager includes a miniature commercial video camera with an adjustable lens, a modified compression coin cell imager with a fiat circular principal detector element, and a sample mounted on a transparent circular glass disk, and provides NMR information as well as a video image of a sample, such as a polymer film, with micrometer resolution.

  4. Advancing biomedical imaging

    PubMed Central

    Weissleder, Ralph; Nahrendorf, Matthias

    2015-01-01

    Imaging reveals complex structures and dynamic interactive processes, located deep inside the body, that are otherwise difficult to decipher. Numerous imaging modalities harness every last inch of the energy spectrum. Clinical modalities include magnetic resonance imaging (MRI), X-ray computed tomography (CT), ultrasound, and light-based methods [endoscopy and optical coherence tomography (OCT)]. Research modalities include various light microscopy techniques (confocal, multiphoton, total internal reflection, superresolution fluorescence microscopy), electron microscopy, mass spectrometry imaging, fluorescence tomography, bioluminescence, variations of OCT, and optoacoustic imaging, among a few others. Although clinical imaging and research microscopy are often isolated from one another, we argue that their combination and integration is not only informative but also essential to discovering new biology and interpreting clinical datasets in which signals invariably originate from hundreds to thousands of cells per voxel. PMID:26598657

  5. Nuclear medicine hepatobiliary imaging.

    PubMed

    Ziessman, Harvey A

    2010-02-01

    Nuclear medicine hepatobilary imaging (HIDA) is a time proven imaging methodology that uses radioactive drugs and specialized cameras to make imaging diagnoses based on physiology. HIDA radiopharmaceuticals are extracted by hepatocytes in the liver and cleared through the biliary system similar to bilirubin. The most common indication for HIDA imaging is acute cholecystitis, diagnosed by nonfilling of the gallbladder due to cystic duct obstruction. HIDA can detect high grade biliary obstruction prior to ductal dilatation; images reveal a persistent hepatogram without biliary clearance due to the high backpressure. HIDA also aids in the diagnosis of partial biliary obstruction due to stones, biliary stricture, and sphincter of Oddi obstruction. It can confirm biliary leakage postcholecystectomy and hepatic transplantation. Calculation of a gallbladder ejection fraction after cholecystokinin infusion is commonly used to diagnose chronic acalculous gallbladder disease. Diseased gallbladders do not contract. There are many other less common but valuable diagnostic indications for HIDA imaging. PMID:19879969

  6. Fractal image compression

    NASA Technical Reports Server (NTRS)

    Barnsley, Michael F.; Sloan, Alan D.

    1989-01-01

    Fractals are geometric or data structures which do not simplify under magnification. Fractal Image Compression is a technique which associates a fractal to an image. On the one hand, the fractal can be described in terms of a few succinct rules, while on the other, the fractal contains much or all of the image information. Since the rules are described with less bits of data than the image, compression results. Data compression with fractals is an approach to reach high compression ratios for large data streams related to images. The high compression ratios are attained at a cost of large amounts of computation. Both lossless and lossy modes are supported by the technique. The technique is stable in that small errors in codes lead to small errors in image data. Applications to the NASA mission are discussed.

  7. Visions image operating system

    SciTech Connect

    Kohler, R.R.; Hanson, A.R.

    1982-01-01

    The image operating system is a complete software environment specifically designed for dynamic experimentation in scene analysis. The IOS consists of a high-level interpretive control language (LISP) with efficient image operators in a noninterpretive language. The image operators are viewed as local operators to be applied in parallel at all pixels to a set of input images. In order to carry out complex image analysis experiments an environment conducive to such experimentation was needed. This environment is provided by the visions image operating system based on a computational structure known as a processing cone proposed by Hanson and Riseman (1974, 1980) and implemented on a VAX-11/780 running VMS. 6 references.

  8. Imaging the skin.

    PubMed

    Aspres, Nicholas; Egerton, Ian B; Lim, Adrian C; Shumack, Stephen P

    2003-02-01

    Since the discovery of X-rays, the use of imaging technology has continued to play an important role in medicine. Technological advancements have led to the development of various imaging modalities, most of which have been used to image organs deep within the human body. More recently, attention has focused on the application of imaging technology for evaluation of the skin. A variety of techniques are currently being used to examine the skin and these include specialized photography, surface microscopy, ultrasound, laser Doppler perfusion imaging, confocal microscopy, and magnetic resonance imaging. These modalities can provide information that can assist in the management of skin problems. Although many of these techniques are still undergoing research, they are showing promise as useful clinical tools in dermatology.

  9. Molecular imaging in oncology

    PubMed Central

    Dzik-Jurasz, A S K

    2004-01-01

    Cancer is a genetic disease that manifests in loss of normal cellular homeostatic mechanisms. The biology and therapeutic modulation of neoplasia occurs at the molecular level. An understanding of these molecular processes is therefore required to develop novel prognostic and early biomarkers of response. In addition to clinical applications, increased impetus for the development of such technologies has been catalysed by pharmaceutical companies investing in the development of molecular therapies. The discipline of molecular imaging therefore aims to image these important molecular processes in vivo. Molecular processes, however, operate at short length scales and concentrations typically beyond the resolution of clinical imaging. Solving these issues will be a challenge to imaging research. The successful implementations of molecular imaging in man will only be realised by the close co-operation amongst molecular biologists, chemists and the imaging scientists. PMID:18250026

  10. Biological Imaging Software Tools

    PubMed Central

    Eliceiri, Kevin W.; Berthold, Michael R.; Goldberg, Ilya G.; Ibáñez, Luis; Manjunath, B.S.; Martone, Maryann E.; Murphy, Robert F.; Peng, Hanchuan; Plant, Anne L.; Roysam, Badrinath; Stuurman, Nico; Swedlow, Jason R.; Tomancak, Pavel; Carpenter, Anne E.

    2013-01-01

    Few technologies are more widespread in modern biological laboratories than imaging. Recent advances in optical technologies and instrumentation are providing hitherto unimagined capabilities. Almost all these advances have required the development of software to enable the acquisition, management, analysis, and visualization of the imaging data. We review each computational step that biologists encounter when dealing with digital images, the challenges in that domain, and the overall status of available software for bioimage informatics, focusing on open source options. PMID:22743775

  11. Beam imaging sensor

    DOEpatents

    McAninch, Michael D.; Root, Jeffrey J.

    2016-07-05

    The present invention relates generally to the field of sensors for beam imaging and, in particular, to a new and useful beam imaging sensor for use in determining, for example, the power density distribution of a beam including, but not limited to, an electron beam or an ion beam. In one embodiment, the beam imaging sensor of the present invention comprises, among other items, a circumferential slit that is either circular, elliptical or polygonal in nature.

  12. Manual of diagnostic imaging

    SciTech Connect

    Gaylord, G.; Baker, S.; Davis, L.

    1988-01-01

    This book is on ordering and understanding the results of radiologic studies. Main sections are (I) Diagnostic Radiology serves as a basic introduction; (II) Diagnostic Modalities dedicates a chapter to each imaging modality in a clinical context, with a brief technical description and patient preparation guidelines; and (III) Organ System Imaging contains a chapter on each major organ system, covering the abilities and limitations of each modality to image a specific organ system and the significance of anatomic, physiologic, and general pathologic information.

  13. NMR imaging of materials

    SciTech Connect

    Vinegar, H.J.; Rothwell, W.P.

    1988-03-01

    A method for obtaining at least one petrophysical property of a porous material containing therein at least one preselected fluid, is described, comprising: NMR imaging the material to generate signals dependent upon both M(0) and T/sub 1/ and M(0) and T/sub 2/, generating separate M(0), T/sub 1/ and T/sub 2/ images from the signals, and determining at least one petrophysical property from at least one of the images.

  14. Images of Illness

    PubMed Central

    Longhurst, Mark F.

    1992-01-01

    The images we as physicians retain of our patients have a bearing on the evolution of our clinical behaviour and attributes. These images can enhance our diagnostic and therapeutic skills, increase our capacity to care for people with incurable diseases, and offer insights into our own emotional response. A recollection of five people with Parkinson's disease offers a college of images to give us further insights into the meaning of illness-for the patient and the physician. PMID:20469529

  15. Apple Image Processing Educator

    NASA Technical Reports Server (NTRS)

    Gunther, F. J.

    1981-01-01

    A software system design is proposed and demonstrated with pilot-project software. The system permits the Apple II microcomputer to be used for personalized computer-assisted instruction in the digital image processing of LANDSAT images. The programs provide data input, menu selection, graphic and hard-copy displays, and both general and detailed instructions. The pilot-project results are considered to be successful indicators of the capabilities and limits of microcomputers for digital image processing education.

  16. Image Processing Software

    NASA Technical Reports Server (NTRS)

    1992-01-01

    To convert raw data into environmental products, the National Weather Service and other organizations use the Global 9000 image processing system marketed by Global Imaging, Inc. The company's GAE software package is an enhanced version of the TAE, developed by Goddard Space Flight Center to support remote sensing and image processing applications. The system can be operated in three modes and is combined with HP Apollo workstation hardware.

  17. Multiple wavelength diffractive imaging

    NASA Astrophysics Data System (ADS)

    Chen, Bo; Dilanian, Ruben A.; Teichmann, Sven; Abbey, Brian; Peele, Andrew G.; Williams, Garth J.; Hannaford, Peter; van Dao, Lap; Quiney, Harry M.; Nugent, Keith A.

    2009-02-01

    We demonstrate coherent diffraction imaging using multiple harmonics from a high-harmonic generation source. An algorithm is presented that builds the known incident spectrum into the reconstruction procedure with the result that the useable flux is increased by more than an order of magnitude. Excellent images are obtained with a resolution of (165±5)nm and compare very well with images from a scanning electron microscope.

  18. Grating image technology

    NASA Astrophysics Data System (ADS)

    Iwata, Fujio

    1995-07-01

    The word 'grating image' was first named by Toppan Printing Company, Ltd. It means that an image consists of grating dots. In 1988, we presented this new technology at the Optical Security Systems Symposium, in Switzerland. Then it was improved and applied in display application. Recently, it was further applied in 3D video systems. In this report, the development history and the recent situations of grating image technology are described.

  19. Shuttle imaging radar experiment

    USGS Publications Warehouse

    Elachi, C.; Brown, W.E.; Cimino, J.B.; Dixon, T.; Evans, D.L.; Ford, J.P.; Saunders, R.S.; Breed, C.; Masursky, H.; McCauley, J.F.; Schaber, G.; Dellwig, L.; England, A.; MacDonald, H.; Martin-Kaye, P.; Sabins, F.

    1982-01-01

    The shuttle imaging radar (SIR-A) acquired images of a variety of the earth's geologic areas covering about 10 million square kilometers. Structural and geomorphic features such as faults, folds, outcrops, and dunes are clearly visible in both tropical and arid regions. The combination of SIR-A and Seasat images provides additional information about the surface physical properties: topography and roughness. Ocean features were also observed, including large internal waves in the Andaman Sea. Copyright ?? 1982 AAAS.

  20. Diagnostic imaging of osteosarcoma

    SciTech Connect

    Seeger, L.L.; Gold, R.H.; Chandnani, V.P. )

    1991-09-01

    The diagnosis, treatment planning, and follow-up evaluation of osteosarcoma rely heavily on a variety of imaging techniques. Plain roentgenography, radionuclide bone scanning, computed tomography, and magnetic resonance imaging play important roles in defining local tumor extent, detecting metastatic disease, and monitoring for recurrent tumor. Invasive studies such as angiography are now rarely necessary. In the future, newer imaging modalities, including positron emission tomography, can be expected to become important tools for evaluation of these tumors. 23 references.

  1. Microscopy imaging device with advanced imaging properties

    SciTech Connect

    Ghosh, Kunal; Burns, Laurie; El Gamal, Abbas; Schnitzer, Mark J.; Cocker, Eric; Ho, Tatt Wei

    2015-11-24

    Systems, methods and devices are implemented for microscope imaging solutions. One embodiment of the present disclosure is directed toward an epifluorescence microscope. The microscope includes an image capture circuit including an array of optical sensor. An optical arrangement is configured to direct excitation light of less than about 1 mW to a target object in a field of view of that is at least 0.5 mm.sup.2 and to direct epi-fluorescence emission caused by the excitation light to the array of optical sensors. The optical arrangement and array of optical sensors are each sufficiently close to the target object to provide at least 2.5 .mu.m resolution for an image of the field of view.

  2. Microscopy imaging device with advanced imaging properties

    DOEpatents

    Ghosh, Kunal; Burns, Laurie; El Gamal, Abbas; Schnitzer, Mark J.; Cocker, Eric; Ho, Tatt Wei

    2016-10-25

    Systems, methods and devices are implemented for microscope imaging solutions. One embodiment of the present disclosure is directed toward an epifluorescence microscope. The microscope includes an image capture circuit including an array of optical sensor. An optical arrangement is configured to direct excitation light of less than about 1 mW to a target object in a field of view of that is at least 0.5 mm.sup.2 and to direct epi-fluorescence emission caused by the excitation light to the array of optical sensors. The optical arrangement and array of optical sensors are each sufficiently close to the target object to provide at least 2.5 .mu.m resolution for an image of the field of view.

  3. Breast Imaging Artifacts.

    PubMed

    Odle, Teresa G

    2015-01-01

    Artifacts appear on breast images for a number of reasons. Radiologic technologists play an important role in identifying artifacts that can help or hinder breast cancer diagnosis and in minimizing artifacts that degrade image quality. This article describes various artifacts that occur in breast imaging, along with their causes. The article focuses on artifacts in mammography, with a heavy emphasis on digital mammography, and on magnetic resonance imaging of the breast. Artifacts in ultrasonography of the breast, digital breast tomosynthesis, and positron emission mammography also are discussed.

  4. Ferroelectric optical image comparator

    DOEpatents

    Butler, Michael A.; Land, Cecil E.; Martin, Stephen J.; Pfeifer, Kent B.

    1993-01-01

    A ferroelectric optical image comparator has a lead lanthanum zirconate titanate thin-film device which is constructed with a semi-transparent or transparent conductive first electrode on one side of the thin film, a conductive metal second electrode on the other side of the thin film, and the second electrode is in contact with a nonconducting substrate. A photoinduced current in the device represents the dot product between a stored image and an image projected onto the first electrode. One-dimensional autocorrelations are performed by measuring this current while displacing the projected image.

  5. Ferroelectric optical image comparator

    DOEpatents

    Butler, M.A.; Land, C.E.; Martin, S.J.; Pfeifer, K.B.

    1993-11-30

    A ferroelectric optical image comparator has a lead lanthanum zirconate titanate thin-film device which is constructed with a semi-transparent or transparent conductive first electrode on one side of the thin film, a conductive metal second electrode on the other side of the thin film, and the second electrode is in contact with a nonconducting substrate. A photoinduced current in the device represents the dot product between a stored image and an image projected onto the first electrode. One-dimensional autocorrelations are performed by measuring this current while displacing the projected image. 7 figures.

  6. Marked ghost imaging

    NASA Astrophysics Data System (ADS)

    Chen, Wen; Chen, Xudong

    2014-06-01

    In recent years, ghost imaging has been widely applied in various areas, such as optical security. Here, we report how an object and multiple hidden marks can be simultaneously recovered by using only one rebuilt reference intensity sequence in ghost imaging. The reconstructed object can be clearly observed during the decoding, and multiple marks can be effectively hidden. This unique characteristic is established for ghost imaging system due to random selections of pixels from each reference intensity pattern, which also guarantees high security. This finding may open up a different research perspective for ghost-imaging-based security system.

  7. Contrast image correction method

    NASA Astrophysics Data System (ADS)

    Schettini, Raimondo; Gasparini, Francesca; Corchs, Silvia; Marini, Fabrizio; Capra, Alessandro; Castorina, Alfio

    2010-04-01

    A method for contrast enhancement is proposed. The algorithm is based on a local and image-dependent exponential correction. The technique aims to correct images that simultaneously present overexposed and underexposed regions. To prevent halo artifacts, the bilateral filter is used as the mask of the exponential correction. Depending on the characteristics of the image (piloted by histogram analysis), an automated parameter-tuning step is introduced, followed by stretching, clipping, and saturation preserving treatments. Comparisons with other contrast enhancement techniques are presented. The Mean Opinion Score (MOS) experiment on grayscale images gives the greatest preference score for our algorithm.

  8. Tomographic scanning imager.

    PubMed

    Hovland, Harald

    2009-07-01

    In tomographic scanning (TOSCA) imaging, light from a scene is focused onto a reticle mask using conical scan optics, and collected on a single element detector. Alternatively, one or several detectors replace the reticle. Tomographic processing techniques are then applied to the one-dimensional signal to reproduce a two-dimensional image. The TOSCA technique is presented in detail, including its mathematical foundations and some of its limitations. It is shown how TOSCA imaging can be used in a multispectral configuration, and compares well with more conventional alternatives both in simplicity and performance. Examples of image reconstruction using TOSCA techniques are shown. PMID:19582052

  9. Quantitative luminescence imaging system

    DOEpatents

    Erwin, David N.; Kiel, Johnathan L.; Batishko, Charles R.; Stahl, Kurt A.

    1990-01-01

    The QLIS images and quantifies low-level chemiluminescent reactions in an electromagnetic field. It is capable of real time nonperturbing measurement and simultaneous recording of many biochemical and chemical reactions such as luminescent immunoassays or enzyme assays. The system comprises image transfer optics, a low-light level digitizing camera with image intensifying microchannel plates, an image process or, and a control computer. The image transfer optics may be a fiber image guide with a bend, or a microscope, to take the light outside of the RF field. Output of the camera is transformed into a localized rate of cumulative digitalized data or enhanced video display or hard-copy images. The system may be used as a luminescent microdosimetry device for radiofrequency or microwave radiation, as a thermal dosimeter, or in the dosimetry of ultra-sound (sonoluminescence) or ionizing radiation. It provides a near-real-time system capable of measuring the extremely low light levels from luminescent reactions in electromagnetic fields in the areas of chemiluminescence assays and thermal microdosimetry, and is capable of near-real-time imaging of the sample to allow spatial distribution analysis of the reaction. It can be used to instrument three distinctly different irradiation configurations, comprising (1) RF waveguide irradiation of a small Petri-dish-shaped sample cell, (2) RF irradiation of samples in a microscope for the microscopie imaging and measurement, and (3) RF irradiation of small to human body-sized samples in an anechoic chamber.

  10. Image Registration Workshop Proceedings

    NASA Technical Reports Server (NTRS)

    LeMoigne, Jacqueline (Editor)

    1997-01-01

    Automatic image registration has often been considered as a preliminary step for higher-level processing, such as object recognition or data fusion. But with the unprecedented amounts of data which are being and will continue to be generated by newly developed sensors, the very topic of automatic image registration has become and important research topic. This workshop presents a collection of very high quality work which has been grouped in four main areas: (1) theoretical aspects of image registration; (2) applications to satellite imagery; (3) applications to medical imagery; and (4) image registration for computer vision research.

  11. Wavelets meet genetic imaging

    NASA Astrophysics Data System (ADS)

    Wang, Yu-Ping

    2005-08-01

    Genetic image analysis is an interdisciplinary area, which combines microscope image processing techniques with the use of biochemical probes for the detection of genetic aberrations responsible for cancers and genetic diseases. Recent years have witnessed parallel and significant progress in both image processing and genetics. On one hand, revolutionary multiscale wavelet techniques have been developed in signal processing and applied mathematics in the last decade, providing sophisticated tools for genetic image analysis. On the other hand, reaping the fruit of genome sequencing, high resolution genetic probes have been developed to facilitate accurate detection of subtle and cryptic genetic aberrations. In the meantime, however, they bring about computational challenges for image analysis. In this paper, we review the fruitful interaction between wavelets and genetic imaging. We show how wavelets offer a perfect tool to address a variety of chromosome image analysis problems. In fact, the same word "subband" has been used in the nomenclature of cytogenetics to describe the multiresolution banding structure of the chromosome, even before its appearance in the wavelet literature. The application of wavelets to chromosome analysis holds great promise in addressing several computational challenges in genetics. A variety of real world examples such as the chromosome image enhancement, compression, registration and classification will be demonstrated. These examples are drawn from fluorescence in situ hybridization (FISH) and microarray (gene chip) imaging experiments, which indicate the impact of wavelets on the diagnosis, treatments and prognosis of cancers and genetic diseases.

  12. Miniaturized handheld hyperspectral imager

    NASA Astrophysics Data System (ADS)

    Wu, Huawen; Haibach, Frederick G.; Bergles, Eric; Qian, Jack; Zhang, Charlie; Yang, William

    2014-05-01

    A miniaturized hyperspectral imager is enabled with image sensor integrated with dispersing elements in a very compact form factor, removing the need for expensive, moving, bulky and complex optics that have been used in conventional hyperspectral imagers for decades. The result is a handheld spectral imager that can be installed on miniature UAV drones or conveyor belts in production lines. Eventually, small handhelds can be adapted for use in outpatient medical clinics for point-of-care diagnostics and other in-field applications.

  13. Quantitative luminescence imaging system

    DOEpatents

    Erwin, D.N.; Kiel, J.L.; Batishko, C.R.; Stahl, K.A.

    1990-08-14

    The QLIS images and quantifies low-level chemiluminescent reactions in an electromagnetic field. It is capable of real time nonperturbing measurement and simultaneous recording of many biochemical and chemical reactions such as luminescent immunoassays or enzyme assays. The system comprises image transfer optics, a low-light level digitizing camera with image intensifying microchannel plates, an image process or, and a control computer. The image transfer optics may be a fiber image guide with a bend, or a microscope, to take the light outside of the RF field. Output of the camera is transformed into a localized rate of cumulative digitalized data or enhanced video display or hard-copy images. The system may be used as a luminescent microdosimetry device for radiofrequency or microwave radiation, as a thermal dosimeter, or in the dosimetry of ultra-sound (sonoluminescence) or ionizing radiation. It provides a near-real-time system capable of measuring the extremely low light levels from luminescent reactions in electromagnetic fields in the areas of chemiluminescence assays and thermal microdosimetry, and is capable of near-real-time imaging of the sample to allow spatial distribution analysis of the reaction. It can be used to instrument three distinctly different irradiation configurations, comprising (1) RF waveguide irradiation of a small Petri-dish-shaped sample cell, (2) RF irradiation of samples in a microscope for the microscopic imaging and measurement, and (3) RF irradiation of small to human body-sized samples in an anechoic chamber. 22 figs.

  14. Image Processing System

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Mallinckrodt Institute of Radiology (MIR) is using a digital image processing system which employs NASA-developed technology. MIR's computer system is the largest radiology system in the world. It is used in diagnostic imaging. Blood vessels are injected with x-ray dye, and the images which are produced indicate whether arteries are hardened or blocked. A computer program developed by Jet Propulsion Laboratory known as Mini-VICAR/IBIS was supplied to MIR by COSMIC. The program provides the basis for developing the computer imaging routines for data processing, contrast enhancement and picture display.

  15. Advanced image memory architecture

    NASA Astrophysics Data System (ADS)

    Vercillo, Richard; McNeill, Kevin M.

    1994-05-01

    A workstation for radiographic images, known as the Arizona Viewing Console (AVC), was developed at the University of Arizona Health Sciences Center in the Department of Radiology. This workstation has been in use as a research tool to aid us in investigating how a radiologist interacts with a workstation, to determine which image processing features are required to aid the radiologist, to develop user interfaces and to support psychophysical and clinical studies. Results from these studies have show a need to increase the current image memory's available storage in order to accommodate high resolution images. The current triple-ported image memory can be allocated to store any number of images up to a combined total of 4 million pixels. Over the past couple of years, higher resolution images have become easier to generate with the advent of laser digitizers and computed radiology systems. As part of our research, a larger 32 million pixel image memory for AVC has been designed to replace the existing image memory.

  16. Imaging in Neurooncology

    PubMed Central

    Jacobs, Andreas H.; Kracht, Lutz W.; Gossmann, Axel; Rüger, Maria A.; Thomas, Anne V.; Thiel, Alexander; Herholz, Karl

    2005-01-01

    Summary: Imaging in patients with brain tumors aims toward the determination of the localization, extend, type, and malignancy of the tumor. Imaging is being used for primary diagnosis, planning of treatment including placement of stereotaxic biopsy, resection, radiation, guided application of experimental therapeutics, and delineation of tumor from functionally important neuronal tissue. After treatment, imaging is being used to quantify the treatment response and the extent of residual tumor. At follow-up, imaging helps to determine tumor progression and to differentiate recurrent tumor growth from treatment-induced tissue changes, such as radiation necrosis. A variety of complementary imaging methods are currently being used to obtain all the information necessary to achieve the abovementioned goals. Computed tomography and magnetic resonance imaging (MRI) reveal mostly anatomical information on the tumor, whereas magnetic resonance spectroscopy and positron emission tomography (PET) give important information on the metabolic state and molecular events within the tumor. Functional MRI and functional PET, in combination with electrophysiological methods like transcranial magnetic stimulation, are being used to delineate functionally important neuronal tissue, which has to be preserved from treatment-induced damage, as well as to gather information on tumor-induced brain plasticity. In addition, optical imaging devices have been implemented in the past few years for the development of new therapeutics, especially in experimental glioma models. In summary, imaging in patients with brain tumors plays a central role in the management of the disease and in the development of improved imaging-guided therapies. PMID:15897954

  17. Sparse image reconstruction for molecular imaging.

    PubMed

    Ting, Michael; Raich, Raviv; Hero, Alfred O

    2009-06-01

    The application that motivates this paper is molecular imaging at the atomic level. When discretized at subatomic distances, the volume is inherently sparse. Noiseless measurements from an imaging technology can be modeled by convolution of the image with the system point spread function (psf). Such is the case with magnetic resonance force microscopy (MRFM), an emerging technology where imaging of an individual tobacco mosaic virus was recently demonstrated with nanometer resolution. We also consider additive white Gaussian noise (AWGN) in the measurements. Many prior works of sparse estimators have focused on the case when H has low coherence; however, the system matrix H in our application is the convolution matrix for the system psf. A typical convolution matrix has high coherence. This paper, therefore, does not assume a low coherence H. A discrete-continuous form of the Laplacian and atom at zero (LAZE) p.d.f. used by Johnstone and Silverman is formulated, and two sparse estimators derived by maximizing the joint p.d.f. of the observation and image conditioned on the hyperparameters. A thresholding rule that generalizes the hard and soft thresholding rule appears in the course of the derivation. This so-called hybrid thresholding rule, when used in the iterative thresholding framework, gives rise to the hybrid estimator, a generalization of the lasso. Estimates of the hyperparameters for the lasso and hybrid estimator are obtained via Stein's unbiased risk estimate (SURE). A numerical study with a Gaussian psf and two sparse images shows that the hybrid estimator outperforms the lasso.

  18. BMC Ecology image competition: the winning images

    PubMed Central

    2013-01-01

    BMC Ecology announces the winning entries in its inaugural Ecology Image Competition, open to anyone affiliated with a research institute. The competition, which received more than 200 entries from international researchers at all career levels and a wide variety of scientific disciplines, was looking for striking visual interpretations of ecological processes. In this Editorial, our academic Section Editors and guest judge Dr Yan Wong explain what they found most appealing about their chosen winning entries, and highlight a few of the outstanding images that didn’t quite make it to the top prize. PMID:23517630

  19. Magnetospheric Image Unfolding

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The Grant was a three year grant funded under the Space Physics Supporting Research and Technology and Suborbital Program. Our objective was to develop automated techniques needed to unfold or "invert" global images of the magnetospheric ion populations obtained by the new magnetospheric imaging techniques (ENA, EUV) in anticipation of future missions such as the Magnetospheric Imager and, now, IMAGE. Our focus on the present three year grant is to determine the degree to which such images can quantitatively constrain the global electromagnetic properties of the magnetosphere. In a previous three year grant period we successfully automated a forward modeling inversion algorithm, demonstrated that these inversions are robust in the face of realistic instrumental considerations such as counting statistics and backgrounds, applied error analysis techniques to the extracted parameters using variational procedures, implemented very realistic magnetospheric test images to test the inversion algorithms using the Rice University Magnetospheric Specification Model, and began the process of generating parametric models with the flexibility to handle the realistic magnetospheric images (e.g. Roelof et al, 1992; 1993). Our plan for the present 3 year grant period was to complete the development of the inversion tools needed to handle realistic magnetospheric images, assess the degree to which global electrodynamics is quantitatively constrained by ENA images of the magnetosphere, and bring the inversion of EUV images up to the maturity that we will have achieved for the ENA imaging. Below the accomplishments of our three year effort are present followed by a list of our presentations and publications. The accomplishments of all three years are presented here, and thus some of these items appeared on interim progress reports.

  20. Phase Contrast Imaging

    SciTech Connect

    Menk, Ralf Hendrik

    2008-11-13

    All standard (medical) x-ray imaging technologies, rely primarily on the amplitude properties of the incident radiation, and do not depend on its phase. This is unchanged since the discovery by Roentgen that the intensity of an x-ray beam, as measured by the exposure on a film, was related to the relative transmission properties of an object. However, recently various imaging techniques have emerged which depend on the phase of the x-rays as well as the amplitude. Phase becomes important when the beam is coherent and the imaging system is sensitive to interference phenomena. Significant new advances have been made in coherent optic theory and techniques, which now promise phase information in medical imaging. The development of perfect crystal optics and the increasing availability of synchrotron radiation facilities have contributed to a significant increase in the application of phase based imaging in materials and life sciences. Unique source characteristics such as high intensity, monochromaticity, coherence and high collimating provide an ideal source for advanced imaging. Phase contrast imaging has been applied in both projection and computed tomography modes, and recent applications have been made in the field of medical imaging. Due to the underlying principle of X-ray detection conventional image receptors register only intensities of wave fields and not their phases. During the last decade basically five different methods were developed that translate the phase information into intensity variations. These methods are based on measuring the phase shift {phi} directly (using interference phenomena), the gradient {nabla}{sub {phi}}, or the Laplacian {nabla}{sup 2}{phi}. All three methods can be applied to polychromatic X-ray sources keeping in mind that the native source is synchrotron radiation, featuring monochromatic and reasonable coherent X-ray beams. Due to the vast difference in the coefficients that are driven absorption and phase effects (factor 1