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Sample records for achieve diffraction limited

  1. Mode-converters for rectangular-core fiber amplifiers to achieve diffraction-limited power scaling.

    PubMed

    Sridharan, Arun Kumar; Pax, Paul H; Heebner, John E; Drachenberg, Derrek R; Armstrong, J Paul; Dawson, Jay W

    2012-12-17

    A rectangular-core (ribbon) fiber that guides and amplifies a single higher-order-mode (HOM) can potentially scale to much higher average powers than what is possible in traditional circular-core large-mode-area fibers. Such an amplifier would require mode-conversion at the input to enable interfacing with seed sources that typically output TEM(00) mode radiation and at the output to generate diffraction-limited radiation for end-user applications. We present the first simulation and experimental results of a mode conversion technique that uses two diffractive-optic-elements in conjugate Fourier planes to convert a diffraction limited TEM(00) mode to the HOM of a ribbon fiber. Mode-conversion-efficiency is approximately 84% and can theoretically approach 100%. We also demonstrate a mode-converter system that converts a single HOM of a ribbon fiber back to a diffraction-limited TEM(00) mode. Conversion efficiency is a record 80.5%. PMID:23263119

  2. Diffraction-limited ultrabroadband terahertz spectroscopy

    PubMed Central

    Baillergeau, M.; Maussang, K.; Nirrengarten, T.; Palomo, J.; Li, L. H.; Linfield, E. H.; Davies, A. G.; Dhillon, S.; Tignon, J.; Mangeney, J.

    2016-01-01

    Diffraction is the ultimate limit at which details of objects can be resolved in conventional optical spectroscopy and imaging systems. In the THz spectral range, spectroscopy systems increasingly rely on ultra-broadband radiation (extending over more 5 octaves) making a great challenge to reach resolution limited by diffraction. Here, we propose an original easy-to-implement wavefront manipulation concept to achieve ultrabroadband THz spectroscopy system with diffraction-limited resolution. Applying this concept to a large-area photoconductive emitter, we demonstrate diffraction-limited ultra-broadband spectroscopy system up to 14.5 THz with a dynamic range of 103. The strong focusing of ultrabroadband THz radiation provided by our approach is essential for investigating single micrometer-scale objects such as graphene flakes or living cells, and besides for achieving intense ultra-broadband THz electric fields. PMID:27142959

  3. Diffraction-limited ultrabroadband terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Baillergeau, M.; Maussang, K.; Nirrengarten, T.; Palomo, J.; Li, L. H.; Linfield, E. H.; Davies, A. G.; Dhillon, S.; Tignon, J.; Mangeney, J.

    2016-05-01

    Diffraction is the ultimate limit at which details of objects can be resolved in conventional optical spectroscopy and imaging systems. In the THz spectral range, spectroscopy systems increasingly rely on ultra-broadband radiation (extending over more 5 octaves) making a great challenge to reach resolution limited by diffraction. Here, we propose an original easy-to-implement wavefront manipulation concept to achieve ultrabroadband THz spectroscopy system with diffraction-limited resolution. Applying this concept to a large-area photoconductive emitter, we demonstrate diffraction-limited ultra-broadband spectroscopy system up to 14.5 THz with a dynamic range of 103. The strong focusing of ultrabroadband THz radiation provided by our approach is essential for investigating single micrometer-scale objects such as graphene flakes or living cells, and besides for achieving intense ultra-broadband THz electric fields.

  4. Coherent diffractive imaging: towards achieving atomic resolution.

    PubMed

    Dietze, S H; Shpyrko, O G

    2015-11-01

    The next generation of X-ray sources will feature highly brilliant X-ray beams that will enable the imaging of local nanoscale structures with unprecedented resolution. A general formalism to predict the achievable spatial resolution in coherent diffractive imaging, based solely on diffracted intensities, is provided. The coherent dose necessary to reach atomic resolution depends significantly on the atomic scale structure, where disordered or amorphous materials require roughly three orders of magnitude lower dose compared with the expected scaling of uniform density materials. Additionally, dose reduction for crystalline materials are predicted at certain resolutions based only on their unit-cell dimensions and structure factors. PMID:26524315

  5. Printing colour at the optical diffraction limit.

    PubMed

    Kumar, Karthik; Duan, Huigao; Hegde, Ravi S; Koh, Samuel C W; Wei, Jennifer N; Yang, Joel K W

    2012-09-01

    The highest possible resolution for printed colour images is determined by the diffraction limit of visible light. To achieve this limit, individual colour elements (or pixels) with a pitch of 250 nm are required, translating into printed images at a resolution of ∼100,000 dots per inch (d.p.i.). However, methods for dispensing multiple colourants or fabricating structural colour through plasmonic structures have insufficient resolution and limited scalability. Here, we present a non-colourant method that achieves bright-field colour prints with resolutions up to the optical diffraction limit. Colour information is encoded in the dimensional parameters of metal nanostructures, so that tuning their plasmon resonance determines the colours of the individual pixels. Our colour-mapping strategy produces images with both sharp colour changes and fine tonal variations, is amenable to large-volume colour printing via nanoimprint lithography, and could be useful in making microimages for security, steganography, nanoscale optical filters and high-density spectrally encoded optical data storage. PMID:22886173

  6. Crystallography: Resolution beyond the diffraction limit

    NASA Astrophysics Data System (ADS)

    Shen, Jian-Ren

    2016-02-01

    A method has been devised that extends the resolution of X-ray crystal structures beyond the diffraction limit. This might help to improve the visualization of structures of proteins that form 'poorly diffracting' crystals. See Letter p.202

  7. Physics issues in diffraction limited storage ring design

    NASA Astrophysics Data System (ADS)

    Fan, Wei; Bai, ZhengHe; Gao, WeiWei; Feng, GuangYao; Li, WeiMin; Wang, Lin; He, DuoHui

    2012-05-01

    Diffraction limited electron storage ring is considered a promising candidate for future light sources, whose main characteristics are higher brilliance, better transverse coherence and better stability. The challenge of diffraction limited storage ring design is how to achieve the ultra low beam emittance with acceptable nonlinear performance. Effective linear and nonlinear parameter optimization methods based on Artificial Intelligence were developed for the storage ring physical design. As an example of application, partial physical design of HALS (Hefei Advanced Light Source), which is a diffraction limited VUV and soft X-ray light source, was introduced. Severe emittance growth due to the Intra Beam Scattering effect, which is the main obstacle to achieve ultra low emittance, was estimated quantitatively and possible cures were discussed. It is inspiring that better performance of diffraction limited storage ring can be achieved in principle with careful parameter optimization.

  8. Scalar limitations of diffractive optical elements

    NASA Technical Reports Server (NTRS)

    Johnson, Eric G.; Hochmuth, Diane; Moharam, M. G.; Pommet, Drew

    1993-01-01

    In this paper, scalar limitations of diffractive optic components are investigated using coupled wave analyses. Results are presented for linear phase gratings and fanout devices. In addition, a parametric curve is given which correlates feature size with scalar performance.

  9. Beyond the diffraction limit via optical amplification.

    PubMed

    Kellerer, Aglaé N; Ribak, Erez N

    2016-07-15

    In a previous article [Astron. Astrophys.561, A118 (2014)], we suggested a method to overcome the diffraction limit behind a telescope. We discuss and extend recent numerical simulations and test whether it is indeed possible to use photon amplification to enhance the angular resolution of a telescope or a microscope beyond the diffraction limit. An essential addition is the proposal to select events with an above-average ratio of stimulated to spontaneous photons. The analysis shows that the diffraction limit of a telescope is surpassed by a factor of 10 for an amplifier gain of 200, if the analysis is restricted to a tenth of the incoming astronomical photons. A gain of 70 is sufficient with a hundredth of the photons. More simulations must be performed to account for the bunching of spontaneous photons. PMID:27420490

  10. Optical microscopy beyond the diffraction limit

    PubMed Central

    Smolyaninov, Igor I.

    2008-01-01

    Over the past century the resolution of far-field optical microscopes, which rely on propagating optical modes, was widely believed to be limited because of diffraction to a value on the order of a half-wavelength λ∕2 of the light used. Although immersion microscopes had slightly improved resolution on the order of λ∕2n, the increased resolution was limited by the small range of refractive indices, n, of available transparent materials. We are experiencing quick demolition of the diffraction limit in optical microscopy. Over the past few years numerous nonlinear optical microscopy techniques based on photoswitching and saturation of fluorescence demonstrated far-field resolution of 20 to 30 nm. The latest exciting example of these techniques has been demonstrated by Huang et al. [Science 319, 810–813 (2008)]. Moreover, recent progress in metamaterials indicates that artificial optical media can be created, which do not exhibit the diffraction limit. Resolution of linear “immersion” microscopes based on such metamaterials appears limited only by losses, which can be compensated by gain media. Thus, optical microscopy is quickly moving towards the 10 nm resolution scale, which should bring about numerous revolutionary advances in biomedical imaging. PMID:19404465

  11. Closing the gap to the diffraction limit: Near wavelength limited tabletop soft x-ray coherent diffractive imaging

    NASA Astrophysics Data System (ADS)

    Sandberg, Richard Lunt

    Light microscopy has greatly advanced our understanding of nature. The achievable resolution, however, is limited by optical wavelengths to around 200 nm. Using novel imaging and labeling technologies, resolutions beyond the diffraction limit can be achieved for specialized specimens using techniques such as near-field scanning optical microscopy, stimulated emission depletion microscopy and structured illumination microscopy [1--3]. This dissertation presents a versatile soft x-ray diffraction microscope with 50 nm resolution using tabletop coherent soft x-ray sources. This work represents the first high resolution demonstrations of coherent diffractive or lensless imaging using tabletop extreme ultraviolet and soft x-ray sources [4, 5]. This dissertation also presents the first use of field curvature correction in x-ray coherent imaging which allows high numerical aperture imaging and near-diffraction-limited resolution of 1.5lambda. The relevant theory behind high harmonic generation, the primary tabletop source used in this work, will be discussed as well as the theory behind coherent diffractive imaging. Additionally, the first demonstration of tabletop soft x-ray Fourier Transform holography is shown with important applications to shorter wavelength imaging with high harmonic generation with limited flux. A tabletop soft x-ray diffraction microscope should find broad applications in biology, nanoscience, and materials science due to its simple optical design, high resolution, large depth of field, 3D imaging capability, scalability to shorter wavelengths, and ultrafast temporal resolution.

  12. Coherent imaging at the diffraction limit

    PubMed Central

    Thibault, Pierre; Guizar-Sicairos, Manuel; Menzel, Andreas

    2014-01-01

    X-ray ptychography, a scanning coherent diffractive imaging technique, holds promise for imaging with dose-limited resolution and sensitivity. If the foreseen increase of coherent flux by orders of magnitude can be matched by additional technological and analytical advances, ptychography may approach imaging speeds familiar from full-field methods while retaining its inherently quantitative nature and metrological versatility. Beyond promises of high throughput, spectroscopic applications in three dimensions become feasible, as do measurements of sample dynamics through time-resolved imaging or careful characterization of decoherence effects. PMID:25177990

  13. On the Diffraction Limit for Lensless Imaging

    PubMed Central

    Mielenz, Klaus D.

    1999-01-01

    The diffraction limit for lensless imaging, defined as the sharpest possible point image obtainable with a pinhole aperture, is analyzed and compared to the corresponding limit for imaging with lenses by means of theoretical considerations and numerical computations using the Fresnel-Lommel diffraction theory for circular apertures. The numerical result (u = π) obtained for the best configuration parameter u which defines the optical setup is consistent with the quarter-wave criterion, and is the same as the value reported in a classical paper by Petzval but smaller than the value (u = 1.8π) found by Lord Rayleigh. The smallest discernible detail (pixel) in a composite image is defined by an expression found by Rayleigh on applying the half-wave criterion and is shown to be consistent with the Sparrow criterion of resolution. The numerical values of other measures of image size are reported and compared to equivalent parameters of the Fraunhofer-Airy profile that governs imaging with lenses.

  14. Sub-diffraction-limited optical imaging with superlens and hyperlens

    NASA Astrophysics Data System (ADS)

    Lee, Hyesog

    Optical microscopy has been the most widely used imaging tool in various research disciplines for the last century. However, it has fundamental resolution limit called the Diffraction Limit, which prevents it from observing objects smaller than half of the wavelength. This is caused by the inability of lenses, which are located at far field of the objects, to detect high spatial frequency information encoded in evanescent waves which decay away in the near field. Along with modern technological advancements especially in the field of nanotechnology, numerous innovative ideas sprung up in the past several decades in efforts to break the diffraction barrier and achieve nano-scale optical imaging. The most popular method up to date uses near-field scanning scheme which tends to be very slow and impractical for real-time imaging. Other methods require rather complex imaging optics and multiple measurements of the same sample. So far, true far-field and real-time sub-diffraction-limited optical imaging method is yet to be developed. Here I report new imaging schemes, Superlensing (Near and Far-field superlens) and Hyperlensing, which are capable of not only imaging beyond the Diffraction Limit in resolution but making real-time imaging possible. The Superlens enhances evanescent waves through surface plasmon (SP) resonance. The Far-field Superlens (FSL) scatters them into the far-field and the detected information is then used to numerically reconstruct high resolution image. Hyperlens concept utilizes unusual electromagnetic properties of metamaterials to deliver high spatial frequency information directly into the far-field. It magnifies nano-scale objects just enough for optical microscope to image and no post-imaging process is needed. In this dissertation, detailed experiment designs including nano-fabrication of the superlens and the hyperlens structures were proposed and the first ever imaging results were presented. The resolving power beyond the Diffraction

  15. Sub-diffraction limit resolution in microscopy

    NASA Technical Reports Server (NTRS)

    Cheng, Ming (Inventor); Chen, Weinong (Inventor)

    2007-01-01

    A method and apparatus for visualizing sub-micron size particles employs a polarizing microscope wherein a focused beam of polarized light is projected onto a target, and a portion of the illuminating light is blocked from reaching the specimen, whereby to produce a shadow region, and projecting diffracted light from the target onto the shadow region.

  16. Diffraction-limited step-zoom telescope by image restoration.

    PubMed

    Araiza-Durán, José A; Luna, Esteban; Cornejo-Rodríguez, Alejandro; Sohn, Erika

    2015-11-10

    The design of a step-zoom telescope and its ability to achieve a diffraction-limited performance is explored. The basic idea is to include digital postprocessing to compensate for changes in the modulation transfer function of the system, assuming the knowledge of the range to the object. The instrument is conformed of a two-mirror telescope, two lenses, and a detector. High-quality images and a zoom telescope that ranges from 22 to 61 f-number is achieved by moving the primary mirror and two lenses. The preliminary calculations for the design process and a simulation that shows the performance of the step-zoom telescope are described. PMID:26560774

  17. Shaping the spatial and spectral emissivity at the diffraction limit

    NASA Astrophysics Data System (ADS)

    Makhsiyan, Mathilde; Bouchon, Patrick; Jaeck, Julien; Pelouard, Jean-Luc; Haïdar, Riad

    2015-12-01

    Metasurfaces have attracted a growing interest for their ability to artificially tailor an electromagnetic response on various spectral ranges. In particular, thermal sources with unprecedented abilities, such as directionality or monochromaticity, have been achieved. However, these metasurfaces exhibit homogeneous optical properties whereas the spatial modulation of the emissivity up to the wavelength scale is at the crux of the design of original emitters. In this letter, we study an inhomogeneous metasurface made of a nonperiodic set of optical nano-antennas that spatially and spectrally control the emitted light up to the diffraction limit. Each antenna acts as an independent deep subwavelength emitter for given polarization and wavelength. Their juxtaposition at the subwavelength scale encodes far field multispectral and polarized images. This opens up promising breakthroughs for applications such as optical storage, anti-counterfeit devices, and multispectral emitters for biochemical sensing.

  18. LINC-NIRVANA: cryogenic optics for diffraction limited beam combination

    NASA Astrophysics Data System (ADS)

    Bizenberger, Peter; Baumeister, Harald; Herbst, Tom; Zhang, Xianyu

    2012-09-01

    LINC-NIRVANA is an interferometric imaging camera, which combines the two 8.4 m telescopes of the Large Binocular Telescope (LBT). The instrument operates in the wavelength range from 1.1 μm to 2.4 μm, covering the J, H and K-band, respectively. The beam combining camera (NIRCS) offers the possibility to achieve diffraction limited images with the special resolution of a 23 m telescope. The optics are designed to deliver a 10 arcsec × 10 arcsec field of view with 5 mas resolution. In this paper we describe the evolution of the cryogenic optics, from design and manufacturing to verification. Including the argumentation for decisions we made in order to present a sort of guideline for large cryo-optics. We also present the alignment and testing strategies at a detailed level.

  19. Shaping the spatial and spectral emissivity at the diffraction limit

    SciTech Connect

    Makhsiyan, Mathilde; Bouchon, Patrick Jaeck, Julien; Pelouard, Jean-Luc; Haïdar, Riad

    2015-12-21

    Metasurfaces have attracted a growing interest for their ability to artificially tailor an electromagnetic response on various spectral ranges. In particular, thermal sources with unprecedented abilities, such as directionality or monochromaticity, have been achieved. However, these metasurfaces exhibit homogeneous optical properties whereas the spatial modulation of the emissivity up to the wavelength scale is at the crux of the design of original emitters. In this letter, we study an inhomogeneous metasurface made of a nonperiodic set of optical nano-antennas that spatially and spectrally control the emitted light up to the diffraction limit. Each antenna acts as an independent deep subwavelength emitter for given polarization and wavelength. Their juxtaposition at the subwavelength scale encodes far field multispectral and polarized images. This opens up promising breakthroughs for applications such as optical storage, anti-counterfeit devices, and multispectral emitters for biochemical sensing.

  20. Diffraction-limited 10 microns imaging with 3 meter telescopes

    NASA Technical Reports Server (NTRS)

    Bloemhof, E. E.; Townes, C. H.; Vanderwyck, A. H. B.

    1986-01-01

    An IR imaging system that achieves diffraction-limited spatial resolution (about 0.8 arcsec) at 10 microns on 3-meter ground-based telescopes. The system uses a linear array of sensitive HgCdTe photodiodes, scanned in the direction perpendicular to the array axis, to form two-dimensional images. Scans are completed rapidly enough to freeze atmospheric fluctuations. Individual detectors are small compared to the diameter of the Airy disk, and images are oversampled heavily in the scan direction. This method has a number of advantages for studying small fields with very high spatial resolution, and has been applied successfully to the problem of directly imaging faint circumstellar dust shells.

  1. LINC-NIRVANA: Diffraction limited optics in cryogenic environment

    NASA Astrophysics Data System (ADS)

    Bizenberger, Peter; Baumeister, Harald; Fopp, Patrick; Herbst, Tom; Laun, Werner; Mohr, Lars; Moreno-Ventas, Javier

    2014-07-01

    LINC-NIRVANA is an instrument combining the two 8.4 m telescopes of the Large Binocular Telescope (LBT) coherently, in order to achieve the optical resolution of the 23 meter baseline. For this interferometric instrument concept, the common beam combination requires diffraction limited optical performance. The optics, realized as a Cassegrain telescope design, consists of aluminum mirrors, designed and manufactured to fulfill the challenging specifications required for interferometric imaging. Due to the science wavelength range from 1 μm to 2.4 μm, covering the J, H and K band of the atmosphere, the complete beam combiner including the optics is operated in cryogenic environment at 60 Kelvin. Here, we demonstrate the verification of the optical performance at this temperature for classical in-coherent and coherent illumination. We outline the test setup and present the achieved results of wavefront error for the individual beams and fringe contrast for the interferometric point spread function. This paper continues the already presented integration of the interferometric camera with the focus on the performance of the cryogenic optics.

  2. Collective Effects in a Diffraction Limited Storage Ring

    DOE PAGESBeta

    Nagaoka, Ryutaro; Bane, Karl L.F.

    2015-10-20

    Our paper gives an overview of collective effects that are likely to appear and possibly limit the performance in a diffraction-limited storage ring (DLSR) that stores a high-intensity ultra-low-emittance beam. Beam instabilities and other intensity-dependent effects that may significantly impact the machine performance are covered. The latter include beam-induced machine heating, Touschek scattering, intra-beam scattering, as well as incoherent tune shifts. The general trend that the efforts to achieve ultra-low emittance result in increasing the machine coupling impedance and the beam sensitivity to instability is reviewed. The nature of coupling impedance in a DLSR is described, followed by a seriesmore » of potentially dangerous beam instabilities driven by the former, such as resistive-wall, TMCI (transverse mode coupling instability), head-tail and microwave instabilities. Additionally, beam-ion and CSR (coherent synchrotron radiation) instabilities are also treated. Means to fight against collective effects such as lengthening of the bunch with passive harmonic cavities and bunch-by-bunch transverse feedback are introduced. Numerical codes developed and used to evaluate the machine coupling impedance, as well as to simulate beam instability using the former as inputs are described.« less

  3. Collective Effects in a Diffraction Limited Storage Ring

    SciTech Connect

    Nagaoka, Ryutaro; Bane, Karl L.F.

    2015-10-20

    Our paper gives an overview of collective effects that are likely to appear and possibly limit the performance in a diffraction-limited storage ring (DLSR) that stores a high-intensity ultra-low-emittance beam. Beam instabilities and other intensity-dependent effects that may significantly impact the machine performance are covered. The latter include beam-induced machine heating, Touschek scattering, intra-beam scattering, as well as incoherent tune shifts. The general trend that the efforts to achieve ultra-low emittance result in increasing the machine coupling impedance and the beam sensitivity to instability is reviewed. The nature of coupling impedance in a DLSR is described, followed by a series of potentially dangerous beam instabilities driven by the former, such as resistive-wall, TMCI (transverse mode coupling instability), head-tail and microwave instabilities. Additionally, beam-ion and CSR (coherent synchrotron radiation) instabilities are also treated. Means to fight against collective effects such as lengthening of the bunch with passive harmonic cavities and bunch-by-bunch transverse feedback are introduced. Numerical codes developed and used to evaluate the machine coupling impedance, as well as to simulate beam instability using the former as inputs are described.

  4. Pixel detectors for diffraction-limited storage rings

    PubMed Central

    Denes, Peter; Schmitt, Bernd

    2014-01-01

    Dramatic advances in synchrotron radiation sources produce ever-brighter beams of X-rays, but those advances can only be used if there is a corresponding improvement in X-ray detectors. With the advent of storage ring sources capable of being diffraction-limited (down to a certain wavelength), advances in detector speed, dynamic range and functionality is required. While many of these improvements in detector capabilities are being pursued now, the orders-of-magnitude increases in brightness of diffraction-limited storage ring sources will require challenging non-incremental advances in detectors. This article summarizes the current state of the art, developments underway worldwide, and challenges that diffraction-limited storage ring sources present for detectors. PMID:25177989

  5. Microscopy beyond the diffraction limit using actively controlled single molecules

    PubMed Central

    MOERNER, W.E.

    2013-01-01

    Summary In this short review, the general principles are described for obtaining microscopic images with resolution beyond the optical diffraction limit with single molecules. Although it has been known for several decades that single-molecule emitters can blink or turn on and off, in recent work the addition of on/off control of molecular emission to maintain concentrations at very low levels in each imaging frame combined with sequential imaging of sparse subsets has enabled the reconstruction of images with resolution far below the optical diffraction limit. Single-molecule active control microscopy provides a powerful window into information about nanoscale structures that was previously unavailable. PMID:22582796

  6. Volume Bragg semiconductor lasers with near diffraction limited divergence

    NASA Astrophysics Data System (ADS)

    Venus, George; Glebov, Leonid; Rotar, Vasile; Smirnov, Vadim; Crump, Paul; Farmer, Jason

    2006-05-01

    The problem of high-brightness, narrow line semiconductor lasers sources is important for different kinds of applications. The proposed solution of the problem is the use of an external cavity with volume Bragg grating for effective angular and spectral selection. High-efficient volume Bragg gratings provide complete selection directly in space of wave vectors and serve as a diaphragm in angular space. The condition of effective selection is the provision of a substantial difference in losses for a selected mode by matching angular selectivity of a Bragg grating with divergence of the selected mode. It was proposed off-axis construction of an external cavity with a transmitting volume Bragg grating as an angular selective element and a reflecting volume Bragg grating as a spectral selective feedback. In such external cavity broad area laser diodes have shown stable near-diffraction limited generation in the wide range of pumping current. For LD with 0.5% AR-coated mirror and 150 μm stripe it was achieved 1.7 W output power with divergence of 0.62° at current exceeding six thresholds. Total LD slope efficiency in the considered external cavity is less then slope efficiency of free running diodes by 3-5% only. Spectral width of such locked LD emission was narrowed down to 250 pm in the whole range of pumping current.

  7. Accurate calculation of diffraction-limited encircled and ensquared energy.

    PubMed

    Andersen, Torben B

    2015-09-01

    Mathematical properties of the encircled and ensquared energy functions for the diffraction-limited point-spread function (PSF) are presented. These include power series and a set of linear differential equations that facilitate the accurate calculation of these functions. Asymptotic expressions are derived that provide very accurate estimates for the relative amount of energy in the diffraction PSF that fall outside a square or rectangular large detector. Tables with accurate values of the encircled and ensquared energy functions are also presented. PMID:26368873

  8. Near diffraction limited mid-IR spectromicroscopy using frequency upconversion

    NASA Astrophysics Data System (ADS)

    Sanders, Nicolai; Dam, Jeppe Seidelin; Tidemand-Lichtenberg, Peter; Pedersen, Christian

    2014-02-01

    Mid-infrared microscopy and spectroscopy is interesting due to its medical, biological and chemical applications. Spectromicroscopy can be used for histopathology, sample analysis and diagnosis. The ability to do spectromicroscopy in the 2.5 to 4.5 μm wavelength range where many organic molecules have their fundamental vibrations, with the addition of sufficient spectroscopic resolution to resolve these bands, can e.g. potentially allow for diagnostics without the need for staining of the sample. On a longer timeframe, mid-IR spectromicroscopy has the potential for in-vivo diagnostics, combining morphological and spectral imaging. Recent developments in nonlinear frequency upconversion, have demonstrated the potential to perform both imaging and spectroscopy in the mid-IR range at unparalleled low levels of illumination, the low upconversion detector noise being orders of magnitude below competing technologies. With these applications in mind, we have incorporated microscopy optics into an image upconversion system, achieving near diffraction limited spatial resolution in the 3 μm range. Spectroscopic information is further acquired by appropriate control of the phase match condition of the upconversion process. Multispectral images for a region of interest can be obtained by XY-scanning this region of interest within the field of view of the mid-IR upconversion system. Thus, the whole region of interest can be imaged with all available converter wavelengths, and the spectral representation becomes equal for all points in the image. In addition, the range of converted/imaged wavelengths can be tuned continuously by changing the temperature of the crystal, or discretely by using a different poling channel in the PPLN crystal.

  9. Diffraction-limited high-finesse optical cavities

    SciTech Connect

    Kleckner, Dustin; Irvine, William T. M.; Oemrawsingh, Sumant S. R.; Bouwmeester, Dirk

    2010-04-15

    High-quality optical cavities with wavelength-sized end mirrors are important to the growing field of micro-optomechanical systems. We present a versatile method for calculating the modes of diffraction limited optical cavities and show that it can be used to determine the effect of a wide variety of cavity geometries and imperfections. Additionally, we show these calculations agree remarkably well with FDTD simulations for wavelength-sized optical modes, even though our method is based on the paraxial approximation.

  10. Design examples of diffraction-limited catadioptric objectives

    NASA Astrophysics Data System (ADS)

    Gallert, Frank

    1996-08-01

    The paper relates to different inventions, comprising three diffraction-limited catadioptric designs. All the systems use only spherical shaped surfaces and are designed from one kind of optical material only. In the examples the glass BK7 from the Schott-catalogue was used. The first example gives a three element design reaching equal performance as a Schmidt camera but with only 25 percent of its length. Additionally the field is flat and conveniently located behind the system. The second example is designed to reduce the central obstruction. It's somewhat based on the principle of the Houghton-camera. For a f-number 4 system with 1000 millimeters focal length it gives outstanding image quality at a 5 degree's field--even capable for diffraction-limited visual use. For reduced f-number 5,6 the image is diffraction-limited at the whole field. In terms of color correction it outperforms every Schmidt-Cassegrain or apochromatic triplet of even arbitrarily more reduced light gathering power. The third example is the equivalent for the so-called Wynne corrector triplet that corrects the aberrations of a parabolical mirror. But the invented corrector corrects additionally the spherical aberration of a spherical mirror. The corrector is able to correct all third order aberrations without introducing longitudinal and lateral color.

  11. Breaking resolution limits in ultrafast electron diffraction and microscopy

    PubMed Central

    Baum, Peter; Zewail, Ahmed H.

    2006-01-01

    Ultrafast electron microscopy and diffraction are powerful techniques for the study of the time-resolved structures of molecules, materials, and biological systems. Central to these approaches is the use of ultrafast coherent electron packets. The electron pulses typically have an energy of 30 keV for diffraction and 100–200 keV for microscopy, corresponding to speeds of 33–70% of the speed of light. Although the spatial resolution can reach the atomic scale, the temporal resolution is limited by the pulse width and by the difference in group velocities of electrons and the light used to initiate the dynamical change. In this contribution, we introduce the concept of tilted optical pulses into diffraction and imaging techniques and demonstrate the methodology experimentally. These advances allow us to reach limits of time resolution down to regimes of a few femtoseconds and, possibly, attoseconds. With tilted pulses, every part of the sample is excited at precisely the same time as when the electrons arrive at the specimen. Here, this approach is demonstrated for the most unfavorable case of ultrafast crystallography. We also present a method for measuring the duration of electron packets by autocorrelating electron pulses in free space and without streaking, and we discuss the potential of tilting the electron pulses themselves for applications in domains involving nuclear and electron motions. PMID:17056711

  12. The diffraction limit of an optical spectrum analyzer

    NASA Astrophysics Data System (ADS)

    Kolobrodov, V. G.; Tymchik, G. S.; Kolobrodov, M. S.

    2015-11-01

    This article examines a systematic error that occurs in optical spectrum analyzers and is caused by Fresnel approximation. The aim of the article is to determine acceptable errors of spatial frequency measurement in signal spectrum. The systematic error of spatial frequency measurement has been investigated on the basis of a physical and mathematical model of a coherent spectrum analyzer. It occurs as a result of the transition from light propagation in free space to Fresnel diffraction. Equations used to calculate absolute and relative measurement errors depending on a diffraction angle have been obtained. It allows us to determine the limits of the spectral range according to the given relative error of the spatial frequency measurement.

  13. Genetic algorithm for chromaticity correction in diffraction limited storage rings

    NASA Astrophysics Data System (ADS)

    Ehrlichman, M. P.

    2016-04-01

    A multiobjective genetic algorithm is developed for optimizing nonlinearities in diffraction limited storage rings. This algorithm determines sextupole and octupole strengths for chromaticity correction that deliver optimized dynamic aperture and beam lifetime. The algorithm makes use of dominance constraints to breed desirable properties into the early generations. The momentum aperture is optimized indirectly by constraining the chromatic tune footprint and optimizing the off-energy dynamic aperture. The result is an effective and computationally efficient technique for correcting chromaticity in a storage ring while maintaining optimal dynamic aperture and beam lifetime.

  14. Sub-diffraction-limit imaging using mode multiplexing

    NASA Astrophysics Data System (ADS)

    Wang, Nan; Miyazaki, Jun; He, Jinping; Seto, Keisuke; Kobayashi, Takayoshi

    2015-05-01

    Pixel-by-pixel processed fluorescence difference microscopy is experimentally demonstrated by multiplexing excitation laser beams with Gaussian and donut spot shapes and then demultiplexing the fluorescent signals using lock-in amplifiers. With this scheme, a fixed sample of fluorescent spheres and a slice of mouse brain tissue are imaged with resolutions that exceed the diffraction limit. Compared to previously reported subtraction imaging techniques, this pixel-by-pixel scan can be applied to improve the resolution of a moving sample without introducing subtraction errors. The synchronized signal detection feature makes this method extendible to various applications.

  15. Emittance Adapter for a Diffraction Limited Synchrotron Radiation Source

    SciTech Connect

    Chao, Alexander Wu; Raimondi, Pantaleo; /Frascati

    2012-03-01

    We investigate the possibility of reaching very small horizontal and vertical emittances inside an undulator in a storage ring, by means of a local exchange of the apparent horizontal and vertical emittances, performed with a combination of skew quadrupoles and one solenoid in a dedicated insertion line in the storage ring. The insertion leaves the ring parameters and its optical properties unaffected. This scheme could greatly relax the emittance requirements for a diffraction limited synchrotron light source. The lattice derivation and design is described.

  16. Diffraction-limited storage-ring vacuum technology

    PubMed Central

    Al-Dmour, Eshraq; Ahlback, Jonny; Einfeld, Dieter; Tavares, Pedro Fernandes; Grabski, Marek

    2014-01-01

    Some of the characteristics of recent ultralow-emittance storage-ring designs and possibly future diffraction-limited storage rings are a compact lattice combined with small magnet apertures. Such requirements present a challenge for the design and performance of the vacuum system. The vacuum system should provide the required vacuum pressure for machine operation and be able to handle the heat load from synchrotron radiation. Small magnet apertures result in the conductance of the chamber being low, and lumped pumps are ineffective. One way to provide the required vacuum level is by distributed pumping, which can be realised by the use of a non-evaporable getter (NEG) coating of the chamber walls. It may not be possible to use crotch absorbers to absorb the heat from the synchrotron radiation because an antechamber is difficult to realise with such a compact lattice. To solve this, the chamber walls can work as distributed absorbers if they are made of a material with good thermal conductivity, and distributed cooling is used at the location where the synchrotron radiation hits the wall. The vacuum system of the 3 GeV storage ring of MAX IV is used as an example of possible solutions for vacuum technologies for diffraction-limited storage rings. PMID:25177979

  17. Limited-angle hybrid diffraction tomography for biological samples

    NASA Astrophysics Data System (ADS)

    Kus, A.; Krauze, W.; Kujawinska, M.; Filipiak, M.

    2014-05-01

    In the paper the case of diffraction tomography with limited angle of projections is discussed from the experimental and algorithmic point of views. To reconstruct a 3D distribution of refractive index of an object under study, we use the hybrid approach, which enables to apply the standard Computer Tomography algorithms for phase data obtained by digital holography. We present the results of applying Simultaneous Algebraic Reconstruction Technique together with Anisotropic Total Variation minimization (SART+ATV) on both a phantom object and real data acquired from an experimental setup based on a Mach-Zehnder interferometer configuration. Also, the analysis of the influence of the limited number of projections within a limited angular range is presented. We prove that in the case of simulated data, the limited number of projections captured in a limited angular range can be compensated by higher number of iterations of the algorithm. We also show that SART+ATV method applied for experimental data gives better results than the popular Data Replenishment algorithm.

  18. Dynamic microscale temperature gradient in a gold nanorod solution measured by diffraction-limited nanothermometry

    SciTech Connect

    Li, Chengmingyue; Gan, Xiaosong; Li, Xiangping; Gu, Min

    2015-09-21

    We quantify the dynamic microscale temperature gradient in a gold nanorod solution using quantum-dot-based microscopic fluorescence nanothermometry. By incorporating CdSe quantum dots into the solution as a nanothermometer, precise temperature mapping with diffraction-limited spatial resolution and sub-degree temperature resolution is achieved. The acquired data on heat generation and dissipation show an excellent agreement with theoretical simulations. This work reveals an effective approach for noninvasive temperature regulation with localized nanoheaters in microfluidic environment.

  19. Dynamic microscale temperature gradient in a gold nanorod solution measured by diffraction-limited nanothermometry

    NASA Astrophysics Data System (ADS)

    Li, Chengmingyue; Gan, Xiaosong; Li, Xiangping; Gu, Min

    2015-09-01

    We quantify the dynamic microscale temperature gradient in a gold nanorod solution using quantum-dot-based microscopic fluorescence nanothermometry. By incorporating CdSe quantum dots into the solution as a nanothermometer, precise temperature mapping with diffraction-limited spatial resolution and sub-degree temperature resolution is achieved. The acquired data on heat generation and dissipation show an excellent agreement with theoretical simulations. This work reveals an effective approach for noninvasive temperature regulation with localized nanoheaters in microfluidic environment.

  20. Mesoscopic quantum superposition of the generalized cat state: A diffraction limit

    NASA Astrophysics Data System (ADS)

    Ghosh, Suranjana; Sharma, Raman; Roy, Utpal; Panigrahi, Prasanta K.

    2015-11-01

    The orthogonality of cat and displaced cat states, underlying Heisenberg limited measurement in quantum metrology, is studied in the limit of a large number of states. The mesoscopic superposition of the generalized cat state is correlated with the corresponding state overlap function, controlled by the sub-Planck structures arising from phase-space interference. The asymptotic expression of this overlap function is evaluated, and the validity of large phase-space support and distinguishability of the constituent states, in which context the asymptotic limit is achieved, are discussed in detail. For a large number of coherent states, uniformly located on a circle, the overlap function significantly matches the diffraction pattern for a circular ring source with uniform angular strength. This is in accordance with the van Cittert-Zernike theorem, where the overlap function, similar to the mutual coherence function, matches a diffraction pattern. The physical situation under consideration is delineated in phase space by utilizing the Husimi Q function.

  1. Controllable design of super-oscillatory planar lenses for sub-diffraction-limit optical needles.

    PubMed

    Diao, Jinshuai; Yuan, Weizheng; Yu, Yiting; Zhu, Yechuan; Wu, Yan

    2016-02-01

    Sub-diffraction-limit optical needle can be created by a binary amplitude mask through tailoring the interference of diffraction beams. In this paper, a controllable design of super-oscillatory planar lenses to create sub-diffraction-limit optical needles with the tunable focal length and depth of focus (DOF) is presented. As a high-quality optical needle is influenced by various factors, we first propose a multi-objective and multi-constraint optimization model compromising all the main factors to achieve a needle with the prescribed characteristics. The optimizing procedure is self-designed using the Matlab programming language based on the genetic algorithm (GA) and fast Hankel transform algorithm. Numerical simulations show that the optical needles' properties can be controlled accurately. The optimized results are further validated by the theoretical calculation with the Rayleigh-Sommerfeld integral. The sub-diffraction-limit optical needles can be used in wide fields such as optical nanofabrication, super-resolution imaging, particle acceleration and high-density optical data storage. PMID:26906769

  2. Diffraction-limited lucky imaging with a 12" commercial telescope

    NASA Astrophysics Data System (ADS)

    Baptista, Brian J.

    2014-08-01

    Here we demonstrate a novel lucky imaging camera which is designed to produce diffraction-limited imaging using small telescopes similar to ones used by many academic institutions for outreach and/or student training. We present a design that uses a Meade 12" SCT paired with an Andor iXon fast readout EMCCD. The PSF of the telescope is matched to the pixel size of the EMCCD by adding a simple, custom-fabricated, intervening optical system. We demonstrate performance of the system by observing both astronomical and terrestrial targets. The astronomical application requires simpler data reconstruction techniques as compared to the terrestrial case. We compare different lucky imaging registration and reconstruction algorithms for use with this imager for both astronomical and terrestrial targets. We also demonstrate how this type of instrument would be useful for both undergraduate and graduate student training. As an instructional aide, the instrument can provide a hands-on approach for teaching instrument design, standard data reduction techniques, lucky imaging data processing, and high resolution imaging concepts.

  3. Matter-wave diffraction at the natural limit

    NASA Astrophysics Data System (ADS)

    Brand, Christian; Sclafani, Michele; Knobloch, Christian; Lilach, Yigal; Juffmann, Thomas; Kotakoski, Jani; Mangler, Clemens; Winter, Andreas; Turchanin, Andrey; Meyer, Jannik; Cheshnovsky, Ori; Arndt, Markus

    2016-05-01

    The high sensitivity of matter-wave interferometry experiments to forces and perturbations makes them an essential tool for precision measurements and tests of quantum physics. While mostly grating made of laser-light are used, material gratings have the advantage that they are independent of the particle's internal properties. This makes them universally applicable. However, the molecules will experience substantial van der Waals shifts while passing the grating slits, which suggests limiting this perturbation by reducing the material thickness. In a comprehensive study we compared the van der Waals interactions for free-standing gratings made from single and double layer graphene to masks commonly used in atom interferometry. From the population of high fringe orders we deduce a surprisingly strong electrical interaction between the polarizable molecules and the nanomasks. As even for these thinnest diffraction elements which-path information is not shared with the environment, we interpret this as an experimental affirmation of Bohr's arguments in his famous debate with Einstein.

  4. Ultraviolet diffraction limited nanosurgery of live biological tissues

    NASA Astrophysics Data System (ADS)

    Colombelli, Julien; Grill, Stephan W.; Stelzer, Ernst H. K.

    2004-02-01

    A laser nanodissection system for in vivo and in situ biological tissues is presented. A pulsed laser beam operating at a wavelength of 355 nm enables diffraction limited dissection, providing an optimal tool for intracellular nanosurgery. Coupled into a conventional inverted microscope and scanned across a field of up to 100×100 μm2, this optical nanoscalpel performs in vivo photoablation and plasma-induced ablation inside organisms ranging from intracellular organelles to embryos. The system allows the use of conventional microscopy contrasts and methods, fast dissection with up to 1000 shots per second, and simultaneous dissection and imaging. This article outlines an efficient implementation with a small number of components and reports an improvement of this state of the art of plasma-induced ablation technique over previous studies, with a ratio of plasma volume to beam focal volume of 5.2. This offers, e.g., the possibility of writing information directly at the sample location by plasma glass nanopatterning.

  5. Diffraction-limited imaging on the 200-inch telescope

    NASA Astrophysics Data System (ADS)

    Nakajima, Tadashi

    The technique of non-redundant masking at the Palomar 200-inch telescope and radio VLBI imaging software was used to make optical aperture synthesis maps of two binary stars, Beta Corona Borealis and Sigma Herculis. The dynamic range of the map of Beta CrB, a binary star with a separation of 230 milliarcseconds is 50:1. For Sigma Her, a separation of 70 milliarcseconds was found and the dynamic range of the image is 30:1. These demonstrate the potential of the non-redundant masking technique for diffraction limited imaging of astronomical objects with high dynamic range. It was found that the optimal integration time for measuring the closure phase is longer than that for measuring the fringe amplitude. There is not a close relationship between amplitude errors and phase errors, as is found in radio interferometry. Amplitude self calibration is less effective at optical wavelengths than at radio wavelengths. Primary beam sensitivity correction made in radio aperture is not necessary in optical aperture synthesis. Effects of atmospheric disturbances on optical aperture synthesis were studied by Monte Carlo simulations based on the Kolmogorov theory of refractive-index fluctuations. For the non-redundant masking technique with rc-sized apertures, the simulated fringe amplitude gives an upper bound of the observed fringe amplitude. Monte Carlo simulations are also made to study the sensitivity and resolution of the bispectral analysis of speckle interferometry. The bispectral modulation transfer function and its signal-to-noise ratio at high light levels is presented. The signal-to-noise ratio of the bispectrum at arbitrary light levels is derived in the mid-spatial-frequency range.

  6. Nanofocusing beyond the near-field diffraction limit via plasmonic Fano resonance.

    PubMed

    Song, Maowen; Wang, Changtao; Zhao, Zeyu; Pu, Mingbo; Liu, Ling; Zhang, Wei; Yu, Honglin; Luo, Xiangang

    2016-01-21

    The past decade has witnessed a great deal of optical systems designed for exceeding the Abbe's diffraction limit. Unfortunately, a deep subwavelength spot is obtained at the price of extremely short focal length, which is indeed a near-field diffraction limit that could rarely go beyond in the nanofocusing device. One method to mitigate such a problem is to set up a rapid oscillatory electromagnetic field that converges at the prescribed focus. However, abrupt modulation of phase and amplitude within a small fraction of a wavelength seems to be the main obstacle in the visible regime, aggravated by loss and plasmonic features that come into function. In this paper, we propose a periodically repeated ring-disk complementary structure to break the near-field diffraction limit via plasmonic Fano resonance, originating from the interference between the complex hybrid plasmon resonance and the continuum of propagating waves through the silver film. This plasmonic Fano resonance introduces a π phase jump in the adjacent channels and amplitude modulation to achieve radiationless electromagnetic interference. As a result, deep subwavelength spots as small as 0.0045λ(2) at 36 nm above the silver film have been numerically demonstrated. This plate holds promise for nanolithography, subdiffraction imaging and microscopy. PMID:26691553

  7. High efficiency near diffraction-limited mid-infrared flat lenses based on metasurface reflectarrays

    NASA Astrophysics Data System (ADS)

    Zhang, Shuyan; Kim, Myoung-Hwan; Aieta, Francesco; She, Alan; Mansuripur, Tobias; Gabay, Ilan; Khorasaninejad, Mohammadreza; Rousso, David; Wang, Xiaojun; Troccoli, Mariano; Yu, Nanfang; Capasso, Federico

    2016-08-01

    A limiting factor in the development of mid-infrared optics is the lack of abundant materials that are transparent, low cost, lightweight, and easy to machine. In this paper, we demonstrate a metasurface device that circumvents these limitations. A flat lens based on antenna reflectarrays was designed to achieve near diffraction-limited focusing with a high efficiency (experiment: 80%, simulation: 83%) at 45(o) incidence angle at {\\lambda} = 4.6 {\\mu}m. This geometry considerably simplifies the experimental arrangement compared to the common geometry of normal incidence which requires beam splitters. Simulations show that the effect of comatic aberrations is small compared to parabolic mirrors. The use of single-step photolithography allows large scale fabrication.

  8. Development of integrated mode reformatting components for diffraction-limited spectroscopy.

    PubMed

    MacLachlan, David G; Harris, Robert J; Choudhury, Debaditya; Simmonds, Richard D; Salter, Patrick S; Booth, Martin J; Allington-Smith, Jeremy R; Thomson, Robert R

    2016-01-01

    We present the results of our work on developing fully integrated devices (photonic dicers) for reformatting multimode light to a diffraction limited pseudo-slit. These devices can be used to couple a seeing limited telescope point spread function to a spectrograph operating at the diffraction limit, thus potentially enabling compact, high-resolution spectrographs that are free of modal noise. PMID:26696162

  9. Nanofocusing beyond the near-field diffraction limit via plasmonic Fano resonance

    NASA Astrophysics Data System (ADS)

    Song, Maowen; Wang, Changtao; Zhao, Zeyu; Pu, Mingbo; Liu, Ling; Zhang, Wei; Yu, Honglin; Luo, Xiangang

    2016-01-01

    The past decade has witnessed a great deal of optical systems designed for exceeding the Abbe's diffraction limit. Unfortunately, a deep subwavelength spot is obtained at the price of extremely short focal length, which is indeed a near-field diffraction limit that could rarely go beyond in the nanofocusing device. One method to mitigate such a problem is to set up a rapid oscillatory electromagnetic field that converges at the prescribed focus. However, abrupt modulation of phase and amplitude within a small fraction of a wavelength seems to be the main obstacle in the visible regime, aggravated by loss and plasmonic features that come into function. In this paper, we propose a periodically repeated ring-disk complementary structure to break the near-field diffraction limit via plasmonic Fano resonance, originating from the interference between the complex hybrid plasmon resonance and the continuum of propagating waves through the silver film. This plasmonic Fano resonance introduces a π phase jump in the adjacent channels and amplitude modulation to achieve radiationless electromagnetic interference. As a result, deep subwavelength spots as small as 0.0045λ2 at 36 nm above the silver film have been numerically demonstrated. This plate holds promise for nanolithography, subdiffraction imaging and microscopy.The past decade has witnessed a great deal of optical systems designed for exceeding the Abbe's diffraction limit. Unfortunately, a deep subwavelength spot is obtained at the price of extremely short focal length, which is indeed a near-field diffraction limit that could rarely go beyond in the nanofocusing device. One method to mitigate such a problem is to set up a rapid oscillatory electromagnetic field that converges at the prescribed focus. However, abrupt modulation of phase and amplitude within a small fraction of a wavelength seems to be the main obstacle in the visible regime, aggravated by loss and plasmonic features that come into function. In this

  10. Phase errors in diffraction-limited imaging: contrast limits for sparse aperture masking

    NASA Astrophysics Data System (ADS)

    Ireland, M. J.

    2013-08-01

    Bispectrum phase, closure phase and their generalization to kernel phase are all independent of pupil-plane phase errors to first order. This property, when used with sparse aperture masking behind adaptive optics, has been used recently in high-contrast observations at or inside the formal diffraction limit of large telescopes. Finding the limitations to these techniques requires an understanding of spatial and temporal third-order phase effects, as well as effects such as time-variable dispersion when coupled with the non-zero bandwidths in real observations. In this paper, formulae describing many of these errors are developed, so that a comparison can be made to fundamental noise processes of photon noise and background noise. I show that the current generation of aperture-masking observations of young solar-type stars, taken carefully in excellent observing conditions, are consistent with being limited by temporal phase noise and photon noise. This has relevance for plans to combine pupil remapping with spatial filtering. Finally, I describe calibration strategies for kernel phase, including the optimized calibrator weighting as used for LkCa15, and the restricted kernel phase POISE (phase observationally independent of systematic errors) technique that avoids explicit dependence on calibrators.

  11. Aplanatic beam shaping for diffraction limited beam circularization of tapered laser diodes

    NASA Astrophysics Data System (ADS)

    Heinrich, Arne; Hagen, Clemens; Harlander, Maximilian; Nussbaumer, Bernhard

    2014-03-01

    Many laser applications require a circular, astigmatism-free, diffraction limited, high power beam. A tapered laser diode can generate up to 6 W output power in a diffraction limited beam. However the beam is elliptical and highly astigmatic rendering the design of beam shaping challenging. We present a diffraction limited beam shaping design, especially suitable to circularize and collimate highly astigmatic beams. The setup consists of a simple plano-convex cylindrical lens in the aplanatic condition and an asphere. The first lens matches the divergence of the fast- to the slow axis at the point where the beam is circular while the following asphere collimates the beam. The aplanatic condition is fulfilled by choosing a glass with a specific refractive index depending on the ratio between fast- and slow axis divergence. This cylindrical lens introduces neither spherical error nor primary coma, which makes it insensitive to misalignment. The setup has been tested with a high power laser diode at 980 nm with a 6 mm long taper (angle 6°) and a facet width of 425 μm. The optics have a transmission of about 90% and the resulting beam has a M2 < 1.5. As a proof of principle 3.2 W were coupled into a 15 μm (NA 0.06) LMA fiber with 55% efficiency corresponding to a brightness B = 140 MW/(cm2 sr). Furthermore the presented beam shaping can easily be extended to bars or multiple emitters to reach power levels that are to date only achievable with complex wavelength combination techniques.

  12. An optical super-microscope for far-field, real-time imaging beyond the diffraction limit.

    PubMed

    Wong, Alex M H; Eleftheriades, George V

    2013-01-01

    Optical microscopy suffers from a fundamental resolution limitation arising from the diffractive nature of light. While current solutions to sub-diffraction optical microscopy involve combinations of near-field, non-linear and fine scanning operations, we hereby propose and demonstrate the optical super-microscope (OSM) - a superoscillation-based linear imaging system with far-field working and observation distances - which can image an object in real-time and with sub-diffraction resolution. With our proof-of-principle prototype we report a point spread function with a spot size clearly reduced from the diffraction limit, and demonstrate corresponding improvements in two-point resolution experiments. Harnessing a new understanding of superoscillations, based on antenna array theory, our OSM achieves far-field, sub-diffraction optical imaging of an object without the need for fine scanning, data post-processing or object pre-treatment. Hence the OSM can be used in a wide variety of imaging applications beyond the diffraction limit, including real-time imaging of moving objects. PMID:23612684

  13. An Optical Super-Microscope for Far-field, Real-time Imaging Beyond the Diffraction Limit

    PubMed Central

    Wong, Alex M. H.; Eleftheriades, George V.

    2013-01-01

    Optical microscopy suffers from a fundamental resolution limitation arising from the diffractive nature of light. While current solutions to sub-diffraction optical microscopy involve combinations of near-field, non-linear and fine scanning operations, we hereby propose and demonstrate the optical super-microscope (OSM) – a superoscillation-based linear imaging system with far-field working and observation distances – which can image an object in real-time and with sub-diffraction resolution. With our proof-of-principle prototype we report a point spread function with a spot size clearly reduced from the diffraction limit, and demonstrate corresponding improvements in two-point resolution experiments. Harnessing a new understanding of superoscillations, based on antenna array theory, our OSM achieves far-field, sub-diffraction optical imaging of an object without the need for fine scanning, data post-processing or object pre-treatment. Hence the OSM can be used in a wide variety of imaging applications beyond the diffraction limit, including real-time imaging of moving objects. PMID:23612684

  14. Diffraction limited observations of flux concentrations and sunspot finestructure using adaptive optics

    NASA Astrophysics Data System (ADS)

    Rimmele, T. R.

    2003-05-01

    We present diffraction limited observations of magnetic flux concentrations and penumbral and umbral fine structure within an active region observed at disk center. We recorded g-band images, magnetograms, dopplergrams and narrow-band filtergrams using the Universal Birefringened Filter (UBF) at the Dunn Solar Telescope (DST). The adaptive optics system at the DST was used to achieve diffraction limited long exposure imaging with high signal-to-noise. The main results can be summarized as follows: Strong and spatially narrow downflows are observed at the edge of magnetic structures such as flux tubes, pores and the sunspot umbra. Flux concentrations observed as bright points in intensity expand by about 30-40% from a height close to where the continuum is formed and the height of formation for the g-band. For the particular sunspot observed and at a low altitude in the photosphere we find strong evidence for what appears to be vigorous, small-scale convection patterns in parts of the umbra and a light bridge. We observe extremely narrow (<0.2") channels or sheets of downflowing plasma. We are able to identify individual penumbral fibrils in our data and find a small bright (hot) upflow and a more vertical field structure at the filament "head" near the umbral boundary. The field and flow turn to a nearly horizontal, dark structure within only about 0.2 arcsec. We compare our results with theoretical model predictions.

  15. High Quantum Efficiency Nanopillar Photodiodes Overcoming the Diffraction Limit of Light.

    PubMed

    Lee, Wook-Jae; Senanayake, Pradeep; Farrell, Alan C; Lin, Andrew; Hung, Chung-Hong; Huffaker, Diana L

    2016-01-13

    InAs1-xSbx nanowires have recently attracted interest for infrared sensing applications due to the small bandgap and high thermal conductivity. However, previous reports on nanowire-based infrared sensors required low operating temperatures in order to mitigate the high dark current and have shown poor sensitivities resulting from reduced light coupling efficiency beyond the diffraction limit. Here, InAsSb nanopillar photodiodes with high quantum efficiency are achieved by partially coating the nanopillar with metal that excites localized surface plasmon resonances, leading to quantum efficiencies of ∼29% at 2390 nm. These high quantum efficiency nanopillar photodiodes, with 180 nm diameters and 1000 nm heights, allow operation at temperatures as high as 220 K and exhibit a detection wavelength up to 3000 nm, well beyond the diffraction limit. The InAsSb nanopillars are grown on low cost GaAs (111)B substrates using an InAs buffer layer, making our device architecture a promising path toward low-cost infrared focal plane arrays with high operating temperature. PMID:26682745

  16. Tolerancing of diffraction-limited Kirkpatrick-Baez synchrotron beamline optics for extreme-ultraviolet metrology.

    PubMed

    Naulleau, P P; Goldberg, K A; Batson, P J; Jeong, S; Underwood, J H

    2001-08-01

    The recent interest in extreme-ultraviolet (EUV) lithography has led to the development of an array of at-wavelength metrologies implemented on synchrotron beamlines. These beamlines commonly use Kirkpatrick-Baez (K-B) systems consisting of two perpendicular, elliptically bent mirrors in series. To achieve high-efficiency focusing into a small spot, unprecedented fabrication and assembly tolerance is required of these systems. Here we present a detailed error-budget analysis and develop a set of specifications for diffraction-limited performance for the K-B optic operating on the EUV interferometry beamline at Lawrence Berkeley National Laboratory's Advanced Light Source. The specifications are based on code v modeling tools developed explicitly for these optical systems. Although developed for one particular system, the alignment sensitivities presented here are relevant to K-B system designs in general. PMID:18360402

  17. High efficiency single-mode-multimode-single-mode fiber laser with diffraction-limited beam output.

    PubMed

    Zhou, Jiaqi; He, Bing; Feng, Yan; Gu, Xijia

    2014-08-20

    We designed and tested an all-fiber, high efficiency Yb-doped laser operating at 1088 nm with a single-mode-multimode-single-mode (SMS) structure. A larger-mode-area gain fiber of 1.5 m length, with 20/130 μm core/cladding diameters was used to increase the absorption, and a diffraction-limited Gaussian output beam was obtained from the single-mode output fiber. Using a 976 nm laser diode as the pump source, the laser generated an output power up to 38.5 W with a slope efficiency of 70%. The output beam qualities, with and without SMS structure, were compared and showed that the fiber laser with the SMS structure can achieve high gain, short fiber length, and excellent beam quality. PMID:25321133

  18. Far-field imaging beyond diffraction limit using single sensor in combination with a resonant aperture.

    PubMed

    Li, Lianlin; Li, Fang; Cui, Tie Jun; Yao, Kan

    2015-01-12

    Far-field imaging beyond the diffraction limit is a long sought-after goal in various imaging applications, which requires usually mechanical scanning or an array of antennas. Here, we propose to solve this challenging problem using a single sensor in combination with a spatio-temporal resonant aperture antenna. We theoretically and numerically demonstrate that such resonant aperture antenna is capable of converting part evanescent waves into propagating waves and delivering them to far fields. The proposed imaging concept provides the unique ability to achieve super resolution for real-time data when illuminated by broadband electromagnetic waves, without the harsh requirements such as near- field scanning, mechanical scanning, or antenna arrays. We expect the imaging methodology to make breakthroughs in super-resolution imaging in microwave, terahertz, optical, and ultrasound regimes. PMID:25835685

  19. High efficiency near diffraction-limited mid-infrared flat lenses based on metasurface reflectarrays.

    PubMed

    Zhang, Shuyan; Kim, Myoung-Hwan; Aieta, Francesco; She, Alan; Mansuripur, Tobias; Gabay, Ilan; Khorasaninejad, Mohammadreza; Rousso, David; Wang, Xiaojun; Troccoli, Mariano; Yu, Nanfang; Capasso, Federico

    2016-08-01

    We report the first demonstration of a mid-IR reflection-based flat lens with high efficiency and near diffraction-limited focusing. Focusing efficiency as high as 80%, in good agreement with simulations (83%), has been achieved at 45° incidence angle at λ = 4.6 μm. The off-axis geometry considerably simplifies the optical arrangement compared to the common geometry of normal incidence in reflection mode which requires beam splitters. Simulations show that the effects of incidence angle are small compared to parabolic mirrors with the same NA. The use of single-step photolithography allows large scale fabrication. Such a device is important in the development of compact telescopes, microscopes, and spectroscopic designs. PMID:27505769

  20. Sub-diffraction-limited multilayer coatings for the 0.3-NA Micro-Exposure Tool for extreme ultraviolet lithography

    SciTech Connect

    Soufli, R; Hudyma, R M; Spiller, E; Gullikson, E M; Schmidt, M A; Robinson, J C; Baker, S L; Walton, C C; Taylor, J S

    2007-01-03

    This manuscript discusses the multilayer coating results for the primary and secondary mirrors of the Micro Exposure Tool (MET): a 0.30-numerical aperture (NA) lithographic imaging system with 200 x 600 {micro}m{sup 2} field of view at the wafer plane, operating in the extreme ultraviolet (EUV) wavelength region. Mo/Si multilayers were deposited by DC-magnetron sputtering on large-area, curved MET camera substrates, and a velocity modulation technique was implemented to consistently achieve multilayer thickness profiles with added figure errors below 0.1 nm rms to achieve sub-diffraction-limited performance. This work represents the first experimental demonstration of sub-diffraction-limited multilayer coatings for high-NA EUV imaging systems.

  1. In vitro and in vivo real-time imaging with ultrasonic limited diffraction beams.

    PubMed

    Lu, J Y; Song, T K; Kinnick, R R; Greenleaf, J F

    1993-01-01

    Recently, there has been great interest in a new class of solutions to the isotropic/homogeneous scaler wave equation which represents localized waves or limited diffraction beams in electromagnetics, optics, and acoustics. Applications of these solutions to ultrasonic medical imaging, tissue characterization, and nondestructive evaluation of materials have also been reported. The authors report a real-time medical imager which uses limited diffraction Bessel beams, X-waves, Axicons, or conventional beams. Results (in vitro and in vivo) show that the images obtained with limited diffraction beams have higher resolution and good contrast over larger depth of field compared to images obtained with conventional focused beams. These results suggest the potential clinical usefulness of limited diffraction beams. PMID:18218478

  2. Reaching the Diffraction Limit - Differential Speckle and Wide-Field Imaging for the WIYN Telescope

    NASA Technical Reports Server (NTRS)

    Scott, Nic J.; Howell, Steve; Horch, Elliott

    2016-01-01

    Speckle imaging allows telescopes to achieve diffraction limited imaging performance. The technique requires cameras capable of reading out frames at a very fast rate, effectively 'freezing out' atmospheric seeing. The resulting speckles can be correlated and images reconstructed that are at the diffraction limit of the telescope. These new instruments are based on the successful performance and design of the Differential Speckle Survey Instrument (DSSI).The instruments are being built for the Gemini-N and WIYN telescopes and will be made available to the community via the peer review proposal process. We envision their primary use to be validation and characterization of exoplanet targets from the NASA, K2 and TESS missions and RV discovered exoplanets. Such targets will provide excellent follow-up candidates for both the WIYN and Gemini telescopes. We expect similar data quality in speckle imaging mode with the new instruments. Additionally, both cameras will have a wide-field mode and standard SDSS filters. They will be highly versatile instruments and it is that likely many other science programs will request time on the cameras. The limiting magnitude for speckle observations will remain around 13-14th at WIYN and 16-17th at Gemini, while wide-field, normal CCD imaging operation should be able to go to much fainter, providing usual CCD imaging and photometric capabilities. The instruments will also have high utility as scoring cameras for telescope engineering purposes, or other applications where high time resolution is needed. Instrument support will be provided, including a software pipeline that takes raw speckle data to fully reconstructed images.

  3. Breaking the acoustic diffraction limit in photoacoustic imaging with multiple speckle illumination

    NASA Astrophysics Data System (ADS)

    Chaigne, Thomas; Gateau, Jérôme; Allain, Marc; Katz, Ori; Gigan, Sylvain; Sentenac, Anne; Bossy, Emmanuel

    2016-03-01

    In deep photoacoustic imaging, resolution is inherently limited by acoustic diffraction, and ultrasonic frequencies cannot be arbitrarily increased because of attenuation in tissue. Here we report on the use of multiple speckle illumination to perform super resolution photoacoustic imaging. We show that the analysis of speckle-induced second-order fluctuations of the photoacoustic signal combined with deconvolution enables to resolve optically absorbing structures below the acoustic diffraction limit.

  4. X-ray nanoprobes and diffraction-limited storage rings: opportunities and challenges of fluorescence tomography of biological specimens

    PubMed Central

    de Jonge, Martin D.; Ryan, Christopher G.; Jacobsen, Chris J.

    2014-01-01

    X-ray nanoprobes require coherent illumination to achieve optic-limited resolution, and so will benefit directly from diffraction-limited storage rings. Here, the example of high-resolution X-ray fluorescence tomography is focused on as one of the most voracious demanders of coherent photons, since the detected signal is only a small fraction of the incident flux. Alternative schemes are considered for beam delivery, sample scanning and detectors. One must consider as well the steps before and after the X-ray experiment: sample preparation and examination conditions, and analysis complexity due to minimum dose requirements and self-absorption. By understanding the requirements and opportunities for nanoscale fluorescence tomography, one gains insight into the R&D challenges in optics and instrumentation needed to fully exploit the source advances that diffraction-limited storage rings offer. PMID:25177992

  5. Inexpensive Demonstration of Diffraction-Limited Telescope from NASA Stratospheric Balloons

    NASA Astrophysics Data System (ADS)

    Young, Elliot

    NASA s Balloon Program often flies payloads to altitudes of 120,000 ft or higher, above 99.5% of the atmosphere. At those altitudes, the imaging degradation due to atmospheric- induced wavefront errors is virtually zero. In 2009, the SUNRISE balloon mission quantified the wavefront errors with a Shack-Hartmann array and found no evidence of wavefront errors. This means that a large telescope on a balloon should be able to achieve diffraction-limited performance, provided it can be stabilized at a level that is finer than the diffraction limit. At visible wavelengths, the diffraction limit of a 1 or 2 m telescope is 0.1 arcsec or 0.05 arcsec, respectively. NASA recently demonstrated WASP (the Wallops Arc-Second Pointing system) on a balloon flight in October 2011, a coarse pointing system that kept a dummy telescope (24 ft long, 1500 lbs) stabilized at the 0.25 arcsec level. We propose to use an orthogonal transfer CCD (OTCCD) from MIT Lincoln Laboratory to improve the pointing to 0.05 arcsec, an order of magnitude better than the coarse pointing alone and sufficient to provide long integrations at the diffraction limit of a 2-m telescope. Imaging in visible wavelengths is an important new capability. Ground-based adaptive optics (AO) systems on 8-m and 10-m class telescope cannot effectively correct for atmospheric turbulence at wavelengths shorter than 1 μm; the atmospheric wavefront errors are larger at these wavelengths than in the infrared J-H-K bands. At present, only the Hubble Space Telescope can achieve 0.05 arcsec resolution images in visible wavelengths, a capability that is dramatically oversubscribed. With a camera based on an MIT/LL OTCCD, a 2-m balloon-borne telescope could match the spatial resolution of HST. Under this project (and in conjunction with a SWRI Internal Research proposal), we will perform ground tests of a motion-compensation camera based on an MIT/LL Orthogonal Transfer CCD (OTCCD). This device can shift charge in four directions

  6. What is the diffraction limit? From Airy to Abbe using direct numerical integration

    NASA Astrophysics Data System (ADS)

    Calm, Y. M.; Merlo, J. M.; Burns, M. J.; Kempa, K.; Naughton, M. J.

    The resolution of a conventional optical microscope is sometimes taken from Airy's point spread function (PSF), 0 . 61 λ / NA , and sometimes from Abbe, λ / 2 NA , where NA is the numerical aperture, however modern fluorescence and near-field optical microscopies achieve spatial resolution far better than either of these limits. There is a new category of 2D metamaterials called planar optical elements (POEs), which have a microscopic thickness (< λ), macroscopic transverse dimensions (> 100 λ), and are composed of an array of nanostructured light scatterers. POEs are found in a range of micro- and nano-photonic technologies, and will influence the future optical nanoscopy. With this pretext, we shed some light on the 'diffraction limit' by numerically evaluating Kirchhoff's scalar formulae (in their exact form) and identifying the features of highly non-paraxial, 3D PSFs. We show that the Airy and Abbe criteria are connected, and we comment on the design rules for a particular type of POE: the flat lens. This work is supported by the W. M. Keck Foundation.

  7. Probing local order in glasses from limited-volume electron and x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Liu, A. C. Y.; Tabor, R. F.; Bourgeois, L.; de Jonge, M. D.; Mudie, S. T.; Petersen, T. C.

    2016-05-01

    It has long been recognised that spatial fluctuations in local order in disordered assemblies of particles can be probed using limited-volume diffraction measurements. These measurements have unique advantages over broad-beam diffraction experiments that isotropically average over many structural configurations and result in one-dimensional intensity curves, requiring modelling to interpret. Despite the advantages of limiting illumination to a low number of particle configurations, obtaining quantitative measurements of local order from such experiments remains a challenge. The effects on the diffraction pattern of changing the beam energy, lateral size, aberrations and coherence and the specimen thickness have only recently been clarified. We review theoretical and experimental efforts in this direction in the fields of both electron and x-ray diffraction and identify promising areas of future development.

  8. Image contrast of diffraction-limited telescopes for circular incoherent sources of uniform radiance

    NASA Technical Reports Server (NTRS)

    Shackleford, W. L.

    1980-01-01

    A simple approximate formula is derived for the background intensity beyond the edge of the image of uniform incoherent circular light source relative to the irradiance near the center of the image. The analysis applies to diffraction-limited telescopes with or without central beam obscuration due to a secondary mirror. Scattering off optical surfaces is neglected. The analysis is expected to be most applicable to spaceborne IR telescopes, for which diffraction can be the major source of off-axis response.

  9. Covariance of lucky images for increasing objects contrast: diffraction-limited images in ground-based telescopes

    NASA Astrophysics Data System (ADS)

    Cagigal, Manuel P.; Valle, Pedro J.; Colodro-Conde, Carlos; Villó-Pérez, Isidro; Pérez-Garrido, Antonio

    2016-01-01

    Images of stars adopt shapes far from the ideal Airy pattern due to atmospheric density fluctuations. Hence, diffraction-limited images can only be achieved by telescopes without atmospheric influence, e.g. spatial telescopes, or by using techniques like adaptive optics or lucky imaging. In this paper, we propose a new computational technique based on the evaluation of the COvariancE of Lucky Images (COELI). This technique allows us to discover companions to main stars by taking advantage of the atmospheric fluctuations. We describe the algorithm and we carry out a theoretical analysis of the improvement in contrast. We have used images taken with 2.2-m Calar Alto telescope as a test bed for the technique resulting that, under certain conditions, telescope diffraction limit is clearly reached.

  10. Reconstruction algorithm for limited-angle diffraction tomography for microwave NDE

    SciTech Connect

    Paladhi, P. Roy; Klaser, J.; Tayebi, A.; Udpa, L.; Udpa, S.

    2014-02-18

    Microwave tomography is becoming a popular imaging modality in nondestructive evaluation and medicine. A commonly encountered challenge in tomography in general is that in many practical situations a full 360° angular access is not possible and with limited access, the quality of reconstructed image is compromised. This paper presents an approach for reconstruction with limited angular access in diffraction tomography. The algorithm takes advantage of redundancies in image Fourier space data obtained from diffracted field measurements and couples it to an error minimization technique using a constrained total variation (CTV) minimization. Initial results from simulated data have been presented here to validate the approach.

  11. Overcoming the Diffraction Limit Using Multiple Light Scattering in a Highly Disordered Medium

    PubMed Central

    Choi, Youngwoon; Yang, Taeseok Daniel; Fang-Yen, Christopher; Kang, Pilsung; Lee, Kyoung Jin; Dasari, Ramachandra R.; Feld, Michael S.; Choi, Wonshik

    2012-01-01

    We report that disordered media made of randomly distributed nanoparticles can be used to overcome the diffraction limit of a conventional imaging system. By developing a method to extract the original image information from the multiple scattering induced by the turbid media, we dramatically increase a numerical aperture of the imaging system. As a result, the the resolution is enhanced by more than five times over the diffraction limit and a field of view is extended over the physical area of the camera. Our technique lays the foundation to use a turbid medium as a far-field superlens. PMID:21797607

  12. Two step process for the fabrication of diffraction limited concave microlens arrays.

    PubMed

    Ruffieux, Patrick; Scharf, Toralf; Philipoussis, Irène; Herzig, Hans Peter; Voelkel, Reinhard; Weible, Kenneth J

    2008-11-24

    A two step process has been developed for the fabrication of diffraction limited concave microlens arrays. The process is based on the photoresist filling of melted holes obtained by a preliminary photolithography step. The quality of these microlenses has been tested in a Mach-Zehnder interferometer. The method allows the fabrication of concave microlens arrays with diffraction limited optical performance. Concave microlenses with diameters ranging between 30 microm to 230 microm and numerical apertures up to 0.25 have been demonstrated. As an example, we present the realization of diffusers obtained with random sizes and locations of concave shapes. PMID:19030040

  13. The First Diffraction-Limited Images from the W. M. Keck Telescope

    NASA Technical Reports Server (NTRS)

    Matthews, K.; Ghez, A. M.; Weinberger, A. J.; Neugebauer, G.

    1996-01-01

    The first diffraction limited, 0.05s resolution, images on the W. M. Keck Telescope have been obtained at a wavelength of 2.2 micrometers. These images were part of an experiment to test the suitability of the Keck Telescope for speckle imaging. In order to conduct this test, it was necessary to modify the pixel scale of the Keck facility Near Infrared Camera (NIRC) to optimally sample the spatial frequencies made available by the Keck telescope. The design and implementation of the external reimaging optics, which convert the standard fl25 beam from the secondary mirror to fl182, are described here. Techniques for reducing speckle data with field rotation on an alt-az telescope are also described. Three binary stars were observed in this experiment with separations as small as 0.05s. With only 100 frames of data on each, a dynamic range of at least 3.5 mag was achieved in all cases. These observations imply that a companion as faint as 14.5 mag at 2.2 micrometers could be detected around an 11th magnitude point source.

  14. Printable Nanoscopic Metamaterial Absorbers and Images with Diffraction-Limited Resolution.

    PubMed

    Richner, Patrizia; Eghlidi, Hadi; Kress, Stephan J P; Schmid, Martin; Norris, David J; Poulikakos, Dimos

    2016-05-11

    The fabrication of functional metamaterials with extreme feature resolution finds a host of applications such as the broad area of surface/light interaction. Nonplanar features of such structures can significantly enhance their performance and tunability, but their facile generation remains a challenge. Here, we show that carefully designed out-of-plane nanopillars made of metal-dielectric composites integrated in a metal-dielectric-nanocomposite configuration can absorb broadband light very effectively. We further demonstrate that electrohydrodynamic printing in a rapid nanodripping mode is able to generate precise out-of-plane forests of such composite nanopillars with deposition resolutions at the diffraction limit on flat and nonflat substrates. The nanocomposite nature of the printed material allows the fine-tuning of the overall visible light absorption from complete absorption to complete reflection by simply tuning the pillar height. Almost perfect absorption (∼95%) over the entire visible spectrum is achieved by a nanopillar forest covering only 6% of the printed area. Adjusting the height of individual pillar groups by design, we demonstrate on-demand control of the gray scale of a micrograph with a spatial resolution of 400 nm. These results constitute a significant step forward in ultrahigh resolution facile fabrication of out-of-plane nanostructures, important to a broad palette of light design applications. PMID:27100105

  15. Structuring of photosensitive material below diffraction limit using far field irradiation

    NASA Astrophysics Data System (ADS)

    Yadavalli, Nataraja Sekhar; Saphiannikova, Marina; Lomadze, Nino; Goldenberg, Leonid M.; Santer, Svetlana

    2013-11-01

    In this paper, we report on in-situ atomic force microscopy (AFM) studies of topographical changes in azobenzene-containing photosensitive polymer films that are irradiated with light interference patterns. We have developed an experimental setup consisting of an AFM combined with two-beam interferometry that permits us to switch between different polarization states of the two interfering beams while scanning the illuminated area of the polymer film, acquiring corresponding changes in topography in-situ. This way, we are able to analyze how the change in topography is related to the variation of the electrical field vector within the interference pattern. It is for the first time that with a rather simple experimental approach a rigorous assignment can be achieved. By performing in-situ measurements we found that for a certain polarization combination of two interfering beams [namely for the SP (↕, ↔) polarization pattern] the topography forms surface relief grating with only half the period of the interference patterns. Exploiting this phenomenon we are able to fabricate surface relief structures with characteristic features measuring only 140 nm, by using far field optics with a wavelength of 491 nm. We believe that this relatively simple method could be extremely valuable to, for instance, produce structural features below the diffraction limit at high-throughput, and this could significantly contribute to the search of new fabrication strategies in electronics and photonics industry.

  16. An experimental apparatus for diffraction-limites soft x-ray nanofocusing

    SciTech Connect

    Merthe, Daniel; Goldberg, Kenneth; Yashchuk, Valeriy; Yuan, Sheng; McKinney, Wayne; Celestre, Richard; Mochi, Iacopo; Macdougall, James; Morrison, Gregory; Rakawa, Senajith; Anderson, Erik; Smith, Brian; Domning, Edward; Warwick, Tony; Padmore, Howard

    2011-10-21

    Realizing the experimental potential of high-brightness, next generation synchrotron and free-electron laser light sources requires the development of reflecting x-ray optics capable of wavefront preservation and high-resolution nano-focusing. At the Advanced Light Source (ALS) beamline 5.3.1, we are developing broadly applicable, high-accuracy, in situ, at-wavelength wavefront measurement techniques to surpass 100-nrad slope measurement accuracy for diffraction-limited Kirkpatrick-Baez (KB) mirrors. The at-wavelength methodology we are developing relies on a series of wavefront-sensing tests with increasing accuracy and sensitivity, including scanning-slit Hartmann tests, grating-based lateral shearing interferometry, and quantitative knife-edge testing. We describe the original experimental techniques and alignment methodology that have enabled us to optimally set a bendable KB mirror to achieve a focused, FWHM spot size of 150 nm, with 1 nm (1.24 keV) photons at 3.7 mrad numerical aperture. The predictions of wavefront measurement are confirmed by the knife-edge testing.The side-profiled elliptically bent mirror used in these one-dimensional focusing experiments was originally designed for a much different glancing angle and conjugate distances. This work demonstrates that high-accuracy, at-wavelength wavefront-slope feedback can be used to optimize the pitch, roll, and mirror-bending forces in situ, using procedures that are deterministic and repeatable.

  17. Band-limited double-step Fresnel diffraction and its application to computer-generated holograms.

    PubMed

    Okada, Naohisa; Shimobaba, Tomoyoshi; Ichihashi, Yasuyuki; Oi, Ryutaro; Yamamoto, Kenji; Oikawa, Minoru; Kakue, Takashi; Masuda, Nobuyuki; Ito, Tomoyoshi

    2013-04-01

    Double-step Fresnel diffraction (DSF) is an efficient diffraction calculation in terms of the amount of usage memory and calculation time. This paper describes band-limited DSF, which will be useful for large computer-generated holograms (CGHs) and gigapixel digital holography, mitigating the aliasing noise of the DSF. As the application, we demonstrate a CGH generation with nearly 8K × 4K pixels from texture and depth maps of a three-dimensional scene captured by a depth camera. PMID:23572007

  18. Breaking the diffraction limit of light-sheet fluorescence microscopy by RESOLFT

    PubMed Central

    Hoyer, Patrick; de Medeiros, Gustavo; Balázs, Bálint; Norlin, Nils; Besir, Christina; Hanne, Janina; Kräusslich, Hans-Georg; Engelhardt, Johann; Sahl, Steffen J.; Hell, Stefan W.; Hufnagel, Lars

    2016-01-01

    We present a plane-scanning RESOLFT [reversible saturable/switchable optical (fluorescence) transitions] light-sheet (LS) nanoscope, which fundamentally overcomes the diffraction barrier in the axial direction via confinement of the fluorescent molecular state to a sheet of subdiffraction thickness around the focal plane. To this end, reversibly switchable fluorophores located right above and below the focal plane are transferred to a nonfluorescent state at each scanning step. LS-RESOLFT nanoscopy offers wide-field 3D imaging of living biological specimens with low light dose and axial resolution far beyond the diffraction barrier. We demonstrate optical sections that are thinner by 5–12-fold compared with their conventional diffraction-limited LS analogs. PMID:26984498

  19. Breaking the diffraction limit of light-sheet fluorescence microscopy by RESOLFT

    NASA Astrophysics Data System (ADS)

    Hoyer, Patrick; de Medeiros, Gustavo; Balázs, Bálint; Norlin, Nils; Besir, Christina; Hanne, Janina; Kräusslich, Hans-Georg; Engelhardt, Johann; Sahl, Steffen J.; Hell, Stefan W.; Hufnagel, Lars

    2016-03-01

    We present a plane-scanning RESOLFT [reversible saturable/switchable optical (fluorescence) transitions] light-sheet (LS) nanoscope, which fundamentally overcomes the diffraction barrier in the axial direction via confinement of the fluorescent molecular state to a sheet of subdiffraction thickness around the focal plane. To this end, reversibly switchable fluorophores located right above and below the focal plane are transferred to a nonfluorescent state at each scanning step. LS-RESOLFT nanoscopy offers wide-field 3D imaging of living biological specimens with low light dose and axial resolution far beyond the diffraction barrier. We demonstrate optical sections that are thinner by 5-12-fold compared with their conventional diffraction-limited LS analogs.

  20. Breaking the diffraction limit of light-sheet fluorescence microscopy by RESOLFT.

    PubMed

    Hoyer, Patrick; de Medeiros, Gustavo; Balázs, Bálint; Norlin, Nils; Besir, Christina; Hanne, Janina; Kräusslich, Hans-Georg; Engelhardt, Johann; Sahl, Steffen J; Hell, Stefan W; Hufnagel, Lars

    2016-03-29

    We present a plane-scanning RESOLFT [reversible saturable/switchable optical (fluorescence) transitions] light-sheet (LS) nanoscope, which fundamentally overcomes the diffraction barrier in the axial direction via confinement of the fluorescent molecular state to a sheet of subdiffraction thickness around the focal plane. To this end, reversibly switchable fluorophores located right above and below the focal plane are transferred to a nonfluorescent state at each scanning step. LS-RESOLFT nanoscopy offers wide-field 3D imaging of living biological specimens with low light dose and axial resolution far beyond the diffraction barrier. We demonstrate optical sections that are thinner by 5-12-fold compared with their conventional diffraction-limited LS analogs. PMID:26984498

  1. An alternative approach to achieving water quality-based limits

    SciTech Connect

    Hart, C.M.; Graeser, W.C.

    1995-12-01

    Since May 1982, members of the Iron and Steel Industry have been required to meet effluent limits based on Best Available Technology (BAT) for a process water discharge to receiving stream. US Steel Clairton Works has been successful in meeting these limits in the last three years; however, the current regulatory thrust is toward more stringent limits based on water quality. In cases of smaller streams such as the receiving stream for Clairton Works` process outfall, these limits can be very rigid. This paper will discuss the alternative approaches investigated to meet the new more stringent limits including the solution chosen.

  2. Limit of Detection in X-ray Diffraction Measurements of Tissue Equivalent Samples

    NASA Astrophysics Data System (ADS)

    Zheng, Y.; Vassiljev, N.; Konstantinidis, A.; Griffiths, J.; Speller, R.

    2015-09-01

    There is a suggestion of a new approach to mammography whereby following a conventional mammogram, the radiologist could interrogate suspicious regions using X-ray diffraction whilst the patient is still present and to establish the true extent of disease. A starting point for this work is to quantify the minimum detectable amount of breast cancer within a realistic thickness phantom. Perspex has a similar diffraction pattern to healthy breast tissue whilst water is similar to breast tumour, hence these two materials are used as tissue equivalent test objects for X-ray diffraction measurements. The preliminary results show linear agreement between the ratio of Perspex to water and the ratio of the diffraction peak intensities at 0.7 nm-1 and 1.5 nm-1. The minimum detectable limit for a component of the two ‘tissue’ mix was found to be 4.1%. This suggests that X-ray diffraction can be used to quantify tissue like mixtures down to the 4.1% / 95.9% mix level and hence has a strong potential for delineating the extent of infiltration disease.

  3. The Magellan Adaptive Secondary VisAO Camera: diffraction-limited broadband visible imaging and 20mas fiber array IFU

    NASA Astrophysics Data System (ADS)

    Kopon, Derek; Close, Laird M.; Males, Jared; Gasho, Victor; Follette, Katherine

    2010-07-01

    The Magellan Adaptive Secondary AO system, scheduled for first light in the fall of 2011, will be able to simultaneously perform diffraction limited AO science in both the mid-IR, using the BLINC/MIRAC4 10μm camera, and in the visible using our novel VisAO camera. The VisAO camera will be able to operate as either an imager, using a CCD47 with 8.5 mas pixels, or as an IFS, using a custom fiber array at the focal plane with 20 mas elements in its highest resolution mode. In imaging mode, the VisAO camera will have a full suite of filters, coronagraphic focal plane occulting spots, and SDI prism/filters. The imaging mode should provide ~20% mean Strehl diffraction-limited images over the band 0.5-1.0 μm. In IFS mode, the VisAO instrument will provide R~1,800 spectra over the band 0.6-1.05 μm. Our unprecedented 20 mas spatially resolved visible spectra would be the highest spatial resolution achieved to date, either from the ground or in space. We also present lab results from our recently fabricated advanced triplet Atmospheric Dispersion Corrector (ADC) and the design of our novel wide-field acquisition and active optics lens. The advanced ADC is designed to perform 58% better than conventional doublet ADCs and is one of the enabling technologies that will allow us to achieve broadband (0.5-1.0μm) diffraction limited imaging and wavefront sensing in the visible.

  4. Photonic nanojet of cylindrical metalens assembled by hexagonally arranged nanofibers for breaking the diffraction limit.

    PubMed

    Yue, Liyang; Yan, Bing; Wang, Zengbo

    2016-04-01

    We designed a novel cylindrical metalens assembled by hexagonally arranged close-contact nanofibers. A near-field focusing nanojet with a full-width at half-maximum (FWHM) waist, 26.7% smaller than the Abbe diffraction limit for 532 nm wavelength light, is observed at the bottom of a 1600 nm diameter cylindrical metalens assembled by 160 nm diameter nanofibers irradiated by a plane wave from the top. Using differently sized nanofibers as building blocks to assemble the metalens, the waist size of the produced photonic nanojet in the near-field zone and the lateral resolution of the focus can be flexibly adjusted, simultaneously breaking the diffraction limit. PMID:27192230

  5. An off-axis, wide-field, diffraction-limited, reflective Schmidt Telescope

    NASA Astrophysics Data System (ADS)

    Saunders, Will

    2010-07-01

    Off-axis telescopes with unobstructed pupils offer great advantages in terms of emissivity, throughput, and diffractionlimited energy concentration. For most telescope designs, implementation of an off-axis configuration imposes enormous penalties in terms of cost, optical difficulty and performance, and for this reason off-axis telescopes are rarely constructed. However, for the reflective Schmidt design, implementation of an off-axis configuration is very straightforward, and involves only a modest optical penalty. Moreover, the reflective Schmidt gets particular benefits, avoiding the obstruction of its large focal plane and support column, and gaining a highly accessible, gravity-invariant prime focus, capable of accommodating very large instrumentation. We present an off-axis f/8 reflective Schmidt design for the proposed 'KDUST' Chinese infrared telescope at Dome A on the Antarctic plateau, which offers simultaneous diffraction-limited NIR imaging over 1°, and close to diffraction-limited imaging out to 2° for fibre-fed NIR spectroscopy.

  6. Sub-diffraction limited structuring of solid targets with femtosecond laser pulses.

    PubMed

    Korte, F; Adams, S; Egbert, A; Fallnich, C; Ostendorf, A; Nolte, S; Will, M; Ruske, J P; Chichkov, B; Tuennermann, A

    2000-07-17

    Possibilities to produce sub-diffraction limited structures in thin metal films and bulk dielectric materials using femtosecond laser pulses are investigated. The physics of ultrashort pulse laser ablation of solids is outlined. Results on the fabrication of sub-micrometer structures in 100-200 nm chrome-coated surfaces by direct ablative writing are reported. Polarization maintaining optical waveguides produced by femtosecond laser pulses inside crystalline quartz are demonstrated. PMID:19404368

  7. Cryogenic, high power, near diffraction limited, Yb:YAG slab laser.

    PubMed

    Ganija, Miftar; Ottaway, David; Veitch, Peter; Munch, Jesper

    2013-03-25

    A cryogenic slab laser that is suitable for scaling to high power, while taking full advantage of the improved thermo-optical and thermo-mechanical properties of Yb:YAG at cryogenic temperatures is described. The laser uses a conduction cooled, end pumped, zigzag slab geometry resulting in a near diffraction limited, robust, power scalable design. The design and the initial characterization of the laser up to 200W are presented. PMID:23546080

  8. Simulations for diffraction limited near-infrared adaptive optics systems on the AOF

    NASA Astrophysics Data System (ADS)

    Le Louarn, Miska; Glindemann, A.; Hubin, N.; Marchetti, E.; Madec, P.-Y.

    2010-07-01

    In this paper, we simulate different possibilities to upgrade the Adaptive Optics Facility (AOF) of the VLT, to reach the diffraction limit in the near infrared. We present simulations of Ground Layer AO, Laser Tomography AO, Multi-Conjugate AO, Dual AO and a hybrid system which is a simplified version of MCAO. We describe the strengths and weaknesses of each approach and summarize the studies to be still carried out.

  9. Achievements and Limitations of Evidence-Based Medicine.

    PubMed

    Sheridan, Desmond J; Julian, Desmond G

    2016-07-12

    Evidence-based medicine (EBM) has a long history, but was revived in the early 1990s by a campaign mounted by a movement that took its name. The EBM movement focused attention on the need for greater objectivity in medical decision-making and led to the Cochrane Collaboration, which provides reviews of evidence on the basis of comparative research. Important limitations of EBM's effect on medicine have also emerged. Failure to acknowledge the limitations of clinical trials and systematic reviews has limited their applicability to individual patients' circumstances. An almost exclusive focus on drugs and devices has left vast areas of health care in an evidence vacuum. An overdependence on commissions for its research may have limited its independence in selecting what it investigates. EBM needs to widen its scope beyond drugs and devices to address many areas that often lack evidence at present, notably, health policy, management, and reforms. PMID:27386775

  10. Diffraction limited focal spot in the interaction chamber using phase retrieval adaptive optics

    NASA Astrophysics Data System (ADS)

    Lefaudeux, Nicolas; Lavergne, Emeric; Monchoce, Sylvain; Levecq, Xavier

    2014-03-01

    In order to provide the end user with a diffraction limited collimated beam, adaptive optics phase correction systems are now a standard feature of ultra intense laser facilities. Generally speaking, these systems are based on a deformable mirror controlled in closed loop configuration in order to correct the aberrations of the beam measured by the wavefront sensor. Such implementation corrects for most of the aberrations of the laser. However, the aberrations of the optical elements located downstream of the wavefront sensor are not measured and therefore not corrected by the adaptive optics loop while they are degrading the final focal spot. We present an improved correction strategy and results based on a combination of both usual closed loop and phase retrieval in order to reach the diffraction limit at the focal spot inside the interaction chamber. The off axis parabola alignment camera located at the focal spot is used in combination of the deformable mirror and wavefront sensor to get images of the focal spot. The residual aberrations of the focal spot are measured by a Phase Retrieval algorithm using the acquired focal spot images. Then the adaptive optics loop is run in order to precompensate for these aberrations, which leads to diffraction limited focal spot in the interaction chamber.

  11. Experimental Verification of Overcoming the Diffraction Limit with a Volumetric Veselago-Pendry Transmission-Line Lens

    NASA Astrophysics Data System (ADS)

    Zhu, Jiang; Eleftheriades, George V.

    2008-07-01

    A fully printed Veselago-Pendry lens (isotropic n=-1, ɛr=-1, μr=-1) is presented which is based on transmission-line metamaterials. The lens is constructed in a parallel-plate environment at 1.569 GHz and without any embedded sources and achieves a resolution better than the diffraction limit (full width half power of 0.235λ). Because the lens is low loss (<0.3dB per unit cell), the focused fields are dominated by the evanescent components which dictates that subwavelength tightening of the beam is achieved only in the transverse and not the longitudinal direction. The demonstrated lens is quarter-wavelength thick thus allowing ample “working distance” between the subject/image and the lens.

  12. Pushing the Limits: Achieving Superior Arabic Fluency in America

    ERIC Educational Resources Information Center

    Beaty, Kevin James

    2008-01-01

    This study investigates the current situation of Arabic education in the United States with an overarching question of, "What is the best way for a student of Arabic in the United States to achieve Superior proficiency?" This study focuses on two elite institutions of Arabic education in the United States. This study is based on 3 sources of…

  13. Beat the diffraction limit in 3D direct laser writing in photosensitive glass.

    PubMed

    Bellec, Matthieu; Royon, Arnaud; Bousquet, Bruno; Bourhis, Kevin; Treguer, Mona; Cardinal, Thierry; Richardson, Martin; Canioni, Lionel

    2009-06-01

    Three-dimensional (3D) femtosecond laser direct structuring in transparent materials is widely used for photonic applications. However, the structure size is limited by the optical diffraction. Here we report on a direct laser writing technique that produces subwavelength nanostructures independently of the experimental limiting factors. We demonstrate 3D nanostructures of arbitrary patterns with feature sizes down to 80 nm, less than one tenth of the laser processing wavelength. Its ease of implementation for novel nanostructuring, with its accompanying high precision will open new opportunities for the fabrication of nanostructures for plasmonic and photonic devices and for applications in metamaterials. PMID:19506684

  14. Wavelength dependence of maximal diffraction-limited output power of fiber lasers

    NASA Astrophysics Data System (ADS)

    Otto, Hans-Jürgen; Modsching, Norbert; Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

    2015-03-01

    The threshold-like onset of mode instabilities is currently the main limitation for the scaling of the average output power of fiber-laser systems with diffraction limited beam quality. In this contribution wavelength shifting of the seed signal has been experimentally investigated in order to mitigate mode instabilities. Against the expectations, it is experimentally shown that the highest mode instabilities threshold is reached around 1030 nm and not for the smallest wavelength separation between pump and signal wavelength. This finding implies that the quantum defect is not the sole significant source for thermal heating in the fiber.

  15. Achieving the physical limits of the bounded-storage model

    SciTech Connect

    Mandayam, Prabha; Wehner, Stephanie

    2011-02-15

    Secure two-party cryptography is possible if the adversary's quantum storage device suffers imperfections. For example, security can be achieved if the adversary can store strictly less then half of the qubits transmitted during the protocol. This special case is known as the bounded-storage model, and it has long been an open question whether security can still be achieved if the adversary's storage were any larger. Here, we answer this question positively and demonstrate a two-party protocol which is secure as long as the adversary cannot store even a small fraction of the transmitted pulses. We also show that security can be extended to a larger class of noisy quantum memories.

  16. Superconcentration of light: circumventing the classical limit to achievable irradiance.

    PubMed

    Roth, Stephan; Sheppard, Colin J R; Heintzmann, Rainer

    2016-05-01

    Concentration of light is limited by a fundamental physical principle, which ensures that étendue, the product of area and solid angle, can never decrease in an optical system. In microscopy, many superresolving methods, which can overcome the classical resolution limit, have recently emerged. We propose, and demonstrate experimentally, that it is also possible to circumvent the classical light concentration limit. Actually, most superresolution methods exhibit a common drawback: with respect to the total number of emitted photons, they are less efficient than standard widefield microscopy. Most methods "shave"' the point spread function (PSF) by discarding the disturbing signal from its edge. We show, that in contrast to PSF-shaving, methods related to reassignment microscopy (image scanning microscopy, optical photon reassignment, rescan confocal, instant structured illumination microscopy) concentrate all detected photons in their superresolving images and thereby increase the detected signal per sample area compared to widefield microsopy. We term this behavior superconcentration, as it breaks the classical light concentration limit. PMID:27128086

  17. Diffraction-limited ultrasensitive molecular nano-arrays with singular nano-cone scattering.

    PubMed

    Wang, Yunshan; Chang, Ting-Chou; Stoddart, Paul R; Chang, Hsueh-Chia

    2014-03-01

    Large-library fluorescent molecular arrays remain limited in sensitivity (1 × 10(6) molecules) and dynamic range due to background auto-fluorescence and scattering noise within a large (20-100 μm) fluorescent spot. We report an easily fabricated silica nano-cone array platform, with a detection limit of 100 molecules and a dynamic range that spans 6 decades, due to point (10 nm to 1 μm) illumination of preferentially absorbed tagged targets by singular scattering off wedged cones. Its fluorescent spot reaches diffraction-limited submicron dimensions, which are 10(4) times smaller in area than conventional microarrays, with comparable reduction in detection limit and amplification of dynamic range. PMID:24738011

  18. How diffraction limits ultrasonic screening in phononic plate composed of a periodic array of resonant slits

    NASA Astrophysics Data System (ADS)

    Elayouch, Aliyasin; Addouche, Mahmoud; Lasaygues, Philippe; Achaoui, Younes; Ouisse, Morvan; Khelif, Abdelkrim

    2016-05-01

    We explore experimentally the role played by diffraction in the phenomenon of acoustic shielding provided by a plate that is periodically perforated with subwavelength slits and immersed in water. We carried out ultrasonic transmission measurements for all directions of propagation in order to check the omnidirectionality of acoustic shielding. While a single slit acts as a Fabry-Perot resonator in the frequency range of interest, the coupling between adjacent slits provides an attenuation frequency band centered around the resonant frequency that is mostly independent of the angle of incidence. Beyond the incident angle of 45 degrees, however, we observe the appearance of scattered radiation that limits the attenuation of ultrasound. This spurious scattering is shown to arise from diffraction by the grating of slits. xml:lang="fr"

  19. Long-baseline optical intensity interferometry. Laboratory demonstration of diffraction-limited imaging

    NASA Astrophysics Data System (ADS)

    Dravins, Dainis; Lagadec, Tiphaine; Nuñez, Paul D.

    2015-08-01

    Context. A long-held vision has been to realize diffraction-limited optical aperture synthesis over kilometer baselines. This will enable imaging of stellar surfaces and their environments, and reveal interacting gas flows in binary systems. An opportunity is now opening up with the large telescope arrays primarily erected for measuring Cherenkov light in air induced by gamma rays. With suitable software, such telescopes could be electronically connected and also used for intensity interferometry. Second-order spatial coherence of light is obtained by cross correlating intensity fluctuations measured in different pairs of telescopes. With no optical links between them, the error budget is set by the electronic time resolution of a few nanoseconds. Corresponding light-travel distances are approximately one meter, making the method practically immune to atmospheric turbulence or optical imperfections, permitting both very long baselines and observing at short optical wavelengths. Aims: Previous theoretical modeling has shown that full images should be possible to retrieve from observations with such telescope arrays. This project aims at verifying diffraction-limited imaging experimentally with groups of detached and independent optical telescopes. Methods: In a large optics laboratory, artificial stars (single and double, round and elliptic) were observed by an array of small telescopes. Using high-speed photon-counting solid-state detectors and real-time electronics, intensity fluctuations were cross-correlated over up to 180 baselines between pairs of telescopes, producing coherence maps across the interferometric Fourier-transform plane. Results: These interferometric measurements were used to extract parameters about the simulated stars, and to reconstruct their two-dimensional images. As far as we are aware, these are the first diffraction-limited images obtained from an optical array only linked by electronic software, with no optical connections between the

  20. Compact high-resolution spectrographs for large and extremely large telescopes: using the diffraction limit

    NASA Astrophysics Data System (ADS)

    Robertson, J. Gordon; Bland-Hawthorn, Joss

    2012-09-01

    As telescopes get larger, the size of a seeing-limited spectrograph for a given resolving power becomes larger also, and for ELTs the size will be so great that high resolution instruments of simple design will be infeasible. Solutions include adaptive optics (but not providing full correction for short wavelengths) or image slicers (which give feasible but still large instruments). Here we develop the solution proposed by Bland-Hawthorn and Horton: the use of diffraction-limited spectrographs which are compact even for high resolving power. Their use is made possible by the photonic lantern, which splits a multi-mode optical fiber into a number of single-mode fibers. We describe preliminary designs for such spectrographs, at a resolving power of R ~ 50,000. While they are small and use relatively simple optics, the challenges are to accommodate the longest possible fiber slit (hence maximum number of single-mode fibers in one spectrograph) and to accept the beam from each fiber at a focal ratio considerably faster than for most spectrograph collimators, while maintaining diffraction-limited imaging quality. It is possible to obtain excellent performance despite these challenges. We also briefly consider the number of such spectrographs required, which can be reduced by full or partial adaptive optics correction, and/or moving towards longer wavelengths.

  1. Effective properties of superstructured hyperbolic metamaterials: How to beat the diffraction limit at large focal distance

    NASA Astrophysics Data System (ADS)

    Centeno, Emmanuel; Moreau, Antoine

    2015-07-01

    Superstructured hyperbolic metamaterials (HMs) have been recently introduced to realize media with effective index -1 with the ultimate goal of designing flat lenses of super-resolution power for optical imaging applications. In this work, we analyze the impact on their effective optical properties of defect metallic layers periodically added in HMs. The effective index and losses are systematically calculated in both homogenization and diffractive regimes and with respect to the ratio of dielectric and metallic layers. Although the superstructuring can dramatically decrease the effective losses, we demonstrate that the extent of the hyperbolic dispersion curve in k space plays an even more fundamental role for breaking the diffraction limit. Optimized superstructured HMs working in a regime between the homogenization and diffractive regimes are shown to present simultaneously low effective losses and a high optical resolution for visible light. These superstructured HMs present an effective index of -5 and extend the subwavelength focalization distance up to 2 λ , which is twice as large as for regular HMs.

  2. Interferometric backward third harmonic generation microscopy for axial imaging with accuracy beyond the diffraction limit.

    PubMed

    Sandkuijl, Daaf; Kontenis, Lukas; Coelho, Nuno M; McCulloch, Christopher; Barzda, Virginijus

    2014-01-01

    A new nonlinear microscopy technique based on interference of backward-reflected third harmonic generation (I-THG) from multiple interfaces is presented. The technique is used to measure height variations or changes of a layer thickness with an accuracy of up to 5 nm. Height variations of a patterned glass surface and thickness variations of fibroblasts are visualized with the interferometric epi-THG microscope with an accuracy at least two orders of magnitude better than diffraction limit. The microscopy technique can be broadly applied for measuring distance variations between membranes or multilayer structures inside biological tissue and for surface height variation imaging. PMID:24710103

  3. Near-diffraction-limited laser focusing with a near-critical density plasma lens.

    PubMed

    Shou, Yinren; Lu, Haiyang; Hu, Ronghao; Lin, Chen; Wang, Hongyong; Zhou, Meilin; He, Xiantu; Chen, Jia Erh; Yan, Xueqing

    2016-01-01

    In this Letter, we investigate the feasibility of focusing relativistic laser pulses toward diffraction limit by near-critical density plasma lenses. A theoretical model is developed to estimate the focal length of the plasma lens. Particle-in-cell simulations with various pulse parameters, such as pulse duration, beam waist, and intensity, are performed to show the robustness of plasma lenses. The results prove that the near-critical density plasma lenses can be deployed to obtain higher laser peak intensities with sub-wavelength focal spots in experiments. PMID:26696178

  4. Geometrical configurations of unphased diffraction-limited antennas in passive millimetre-wave imaging systems for concealed weapon detection

    NASA Astrophysics Data System (ADS)

    Serenelli, Roberto

    2004-12-01

    This paper analyzes simple imaging configurations to scan a human body, suitable as passive or active millimetre-wave imaging systems for concealed weapon detection (CWD). The first cylindrical configuration allows a 360 degrees scan: N unphased diffraction-limited antennas each of size L are placed on a circular support surrounding the subject (allowing scanning in the horizontal plane with N non-overlapping independent beams), and this circle is mechanically displaced over the whole body height. An analytical formula gives the maximum obtainable spatial resolution for different dimensions of the circular scanning device and operating frequencies, and the number of receivers achieving this optimal resolution. Constraints to be taken into account are diffraction, the usable total length of the circle, and the full coverage by the N beams over the subject, which is modelled as a cylinder with variable radius, coaxial with the scanning circle. Numerical calculations of system resolution are shown for different operating microwave (MW) and millimetre-wave (MMW) frequencies; in order to study off-axis performances, situations where the subject is not coaxial with the scanning device are also considered. For the case of a parallelepiped to be imaged instead of a cylinder, a linear array configuration is analyzed similarly to the circular one. A theoretical study is carried out to design other curved arrays, filled with unphased diffraction-limited antennas, for the imaging of linear subjects with finer resolution. Finally, the application of such configurations is considered for the design of active imaging systems, and different system architectures are discussed.

  5. Suppression of resonance Raman scattering via ground state depletion towards sub-diffraction-limited label-free microscopy.

    PubMed

    Rieger, Steffen; Fischedick, Markus; Boller, Klaus-Jochen; Fallnich, Carsten

    2016-09-01

    We report on the first experimental demonstration of the suppression of spontaneous Raman scattering via ground state depletion. The concept of Raman suppression can be used to achieve sub-diffraction-limited resolution in label-free microscopy by exploiting spatially selective signal suppression when imaging a sample with a combination of Gaussian- and donut-shaped beams and reconstructing a resolution-enhanced image from this data. Using a nanosecond pulsed laser source with an emission wavelength of 355 nm, the ground state of tris(bipyridine)ruthenium(II) molecules solved in acetonitrile was depleted and the spontaneous Raman scattering at 355 nm suppressed by nearly 50 %. Based on spectroscopic data retrieved from our experiment, we modeled the Raman image of a scattering center in order to demonstrate the applicability of this effect for superresolution Raman microscopy. PMID:27607677

  6. Wavefront correction for near diffraction-limited focal spot on a 6×100 J/1-ns laser facility

    NASA Astrophysics Data System (ADS)

    Fuchs, Julien; Wattellier, Benoit F.; Zou, Ji P.; Chanteloup, Jean-Christophe; Bandulet, H.; Michel, P.; Labaune, C.; Depierreux, S.; Kudryashov, Alexis V.; Aleksandrov, Alexander G.

    2003-10-01

    We have implemented on one beam of the LULI six-beam high-energy (6×100 J, 1 ns) Nd:glass laser facility a closed-loop Adaptive Optics (AO) system to compensate for thermal distortions onto the wave front. Using the AO system composed of a dielectric coated deformable mirror and of a wave front sensor, we are able to improve the wave front quality in order to obtain a focal spot close to the diffraction limit. This allows not only to improve the reproducibility of the experiments but also to increase by at least two orders of magnitude the peak intensity as compared with what usual laser smoothing techniques can achieve.

  7. PIMMS échelle: the next generation of compact diffraction limited spectrographs for arbitrary input beams

    NASA Astrophysics Data System (ADS)

    Betters, Christopher H.; Leon-Saval, Sergio G.; Bland-Hawthorn, Joss; Richards, Samuel N.; Birks, Tim A.; Gris-Sánchez, Itandehui

    2014-07-01

    PIMMS échelle is an extension of previous PIMMS (photonic integrated multimode spectrograph) designs, enhanced by using an échelle diffraction grating as the primary dispersing element for increased spectral band- width. The spectrograph operates at visible wavelengths (550 to 780nm), and is capable of capturing ~100 nm of R > 60, 000 (λ/(triangle)λ) spectra in a single exposure. PIMMS échelle uses a photonic lantern to convert an arbitrary (e.g. incoherent) input beam into N diffraction-limited outputs (i.e. N single-mode fibres). This allows a truly diffraction limited spectral resolution, while also decoupling the spectrograph design from the input source. Here both the photonic lantern and the spectrograph slit are formed using a single length of multi-core fibre. A 1x19 (1 multi-mode fiber to 19 single-mode fibres) photonic lantern is formed by tapering one end of the multi-core fibre, while the other end is used to form a TIGER mode slit (i.e. for a hexagonal grid with sufficient spacing and the correct orientations, the cores of the multi-core fibre can be dispersed such that they do not overlap without additional reformatting). The result is an exceptionally compact, shoebox sized, spectrograph that is constructed primarily from commercial off the shelf components. Here we present a brief overview of the échelle spectrograph design, followed by results from on-sky testing of the breadboard mounted version of the spectrograph at the `UK Schmidt Telescope'.

  8. FRIDA, the diffraction limited NIR imager and IFS for the GTC

    NASA Astrophysics Data System (ADS)

    López, J. A.; Acosta, J.; Álvarez, L. C.; Bringas, V.; Cardiel, N.; Clark, D. M.; Corrales, A.; Cuevas, S.; Chapa, O.; Díaz, J. J., Eikenberry, S. S.; Eliche, C.; Espejo, C.; Flores, R.; Fuentes, J.; Gallego, J.; Garcés, L.; Garzón, F.; Hammersley, P.; Keiman, C.; Lara, G.; López, P.; Lucero, D.; Moreno, H.; Pascual, S.; Patrón, J.; Prieto, A.; Rodríguez, A.; Rodríguez, B.; Sánchez, B.; Torres, D.; Uribe, J.; Watson, A.

    2015-05-01

    FRIDA (InFRared Imager and Dissector for the Adaptive optics system of GTC) is a near infrared, diffraction limited imager and integral field spectrograph that has been designed and is being built as a collaborative project between GTC partner institutions from México, Spain and the USA. FRIDA will operate with the adaptive optics system of GTC. Three different scales are provided in imaging mode, 0.010, 0.020 and 0.040 arcsec pixel^{-1}. The integral field unit is based on a monolithic image slicer that will slice up the field of view into 30 slices. The IFS spaxels have a 2:1 pixels aspect ratio (2 along the spectral axis an 1 along the spatial axis) and it will offer three different spectral resolutions, R ˜ 1000, 5000 and 30,000, the latter over selectable regions in the H & K bands. Thus FRIDA will exploit the diffraction limit of a 10.4 m telescope with superb image quality and spectral resolutions suitable to tackle a large range of topical astrophysical problems. FRIDA has started systems integration and is scheduled to be ready for fully integrated system tests by the end of 2015 and be delivered to GTC shortly after. Here we present an overview of its design, current status and potential scientific applications.

  9. Space infrared telescope facility wide field and diffraction limited array camera (IRAC)

    NASA Technical Reports Server (NTRS)

    Fazio, Giovanni G.

    1988-01-01

    The wide-field and diffraction limited array camera (IRAC) is capable of two-dimensional photometry in either a wide-field or diffraction-limited mode over the wavelength range from 2 to 30 microns with a possible extension to 120 microns. A low-doped indium antimonide detector was developed for 1.8 to 5.0 microns, detectors were tested and optimized for the entire 1.8 to 30 micron range, beamsplitters were developed and tested for the 1.8 to 30 micron range, and tradeoff studies of the camera's optical system performed. Data are presented on the performance of InSb, Si:In, Si:Ga, and Si:Sb array detectors bumpbonded to a multiplexed CMOS readout chip of the source-follower type at SIRTF operating backgrounds (equal to or less than 1 x 10 to the 8th ph/sq cm/sec) and temperature (4 to 12 K). Some results at higher temperatures are also presented for comparison to SIRTF temperature results. Data are also presented on the performance of IRAC beamsplitters at room temperature at both 0 and 45 deg angle of incidence and on the performance of the all-reflecting optical system baselined for the camera.

  10. 100-watt fiber-based green laser with near diffraction-limited beam quality

    NASA Astrophysics Data System (ADS)

    Hu, Dan; Eisenberg, Eric; Brar, Khush; Yilmaz, Tolga; Honea, Eric

    2010-02-01

    An air-cooled, light-weight, fiber-based, high power green laser has been prototyped. The system consists of an all-fibercoupled IR pump laser at 1064 nm and a frequency-conversion module in a compact and flexible configuration. The IR laser operates in QCW mode, with 10 MHz pulse repetition frequency and 3-5 ns pulse width, to generate sufficient peak power for frequency doubling in the converter module. The IR laser can produce more than 200 W in a linearlypolarized diffraction-limited output beam with high spectral brightness for frequency conversion. The converter module has an input telescope and an oven with a nonlinear crystal to efficiently convert the 1064-nm IR fiber laser output to 532-nm green output. The IR laser and conversion module are connected via a stainless-steel protected delivery fiber for optical beam delivery and an electrical cable harness for electrical power delivery and system control. The beam quality of the 532 nm output remains near diffraction-limited, with M2<1.4. Up to 101 W of 532 nm output was demonstrated and multi-hour runs were characterized at 75 W output. The weights of the IR laser package and doubler are 69 lbs and 14 lbs respectively. An overview of the system and full characterization results will be presented. Such compact, highbrightness green laser sources are expected to enable various scientific, defense and industrial applications.

  11. 70-Watt green laser with near diffraction-limited beam quality

    NASA Astrophysics Data System (ADS)

    Hu, Dan; Eisenberg, Eric; Madasamy, Pratheepan; Mead, Roy; Honea, Eric

    2009-02-01

    A 70-Watt green laser with M2<1.4 has been demonstrated. This green laser consists of an all-fiber-based IR pump laser at 1064 nm and a frequency-conversion module in a compact and flexible configuration. The IR laser produces up to 150 Watts in a polarized diffraction-limited output beam with high spectral brightness for frequency conversion. The IR laser is operating under QCW mode, e.g. 10 MHz with 3~5 ns pulse width or 700 MHz with 50 ps pulse width, to generate sufficient peak power for frequency doubling in the converter module. The IR laser and conversion module are connected via a 5-mm stainless-steel protected delivery fiber for optical beam delivery and an electrical cable harness for electrical power delivery and system control. Both the IR laser and converter module are run through embedded software that controls laser operations such as warm up and shut down. System overview and full characterization results will be presented. Such a high power green laser with near diffraction-limited output in a compact configuration will enable various scientific as well as industrial applications.

  12. FRIDA diffraction limited NIR instrument: the challenges of its verification processes

    NASA Astrophysics Data System (ADS)

    Sánchez, Be.; Keiman, C.; Espejo, C.; Cuevas, S.; Álvarez, L. C.; Chapa, O.; Flores-Meza, R.; Fuentes, J.; Garcés, L.; Lara, G.; López, J. A.; Rodríguez, R.; Watson, A.; Bringas, V.; Corrales, A.; Lucero, D.; Rodríguez, A.; Rodríguez, B.; Torres, D.; Uribe, J.

    2014-08-01

    FRIDA (inFRared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias (GTC)) is designed as a diffraction limited instrument that will offer broad and narrow band imaging and integral field spectroscopy capabilities with low, intermediate and high (R ~ 30,000) spectral resolutions, to operate in the wavelength range 0.9 - 2.5 μm. The integral field unit is based on a monolithic image slicer and the imaging and IFS observing modes will use the same Teledyne 2Kx2K detector. FRIDA will be based on a Nasmyth B of GTC, behind the adaptive optics (AO) system. The key scientific objectives of the instrument include studies of solar system bodies, low mass objects, circumstellar outflow phenomena in advanced stages of stellar evolution, active galactic nuclei high redshift galaxies, including resolved stellar populations, semidetached binary systems, young stellar objects and star forming environments. FRIDA subsystems are presently being manufactured and tested. In this paper we present the challenges to perform the verification of some critical specifications of a cryogenic and diffraction limited NIR instrument as FRIDA. FRIDA is a collaborative project between the main GTC partners, namely, Spain, México and Florida.

  13. Conventional transmission electron microscopy imaging beyond the diffraction and information limits.

    PubMed

    Rosenauer, Andreas; Krause, Florian F; Müller, Knut; Schowalter, Marco; Mehrtens, Thorsten

    2014-08-29

    There are mainly two complementary imaging modes in transmission electron microscopy (TEM): Conventional TEM (CTEM) and scanning TEM (STEM). In the CTEM mode the specimen is illuminated with a plane electron wave, and the direct image formed by the objective lens is recorded in the image plane. STEM is based on scanning the specimen surface with a focused electron beam and collecting scattered electrons with an extended disk or ring-shaped detector. Here we show that combination of CTEM imaging with STEM illumination generally allows extending the point resolution of CTEM imaging beyond the diffraction limit. This new imaging mode improves imaging characteristics, is more robust against chromatic aberration, exhibits direct structural imaging with superior precision, visualizes light elements with excellent contrast, and even allows us to overcome the conventional information limit of a microscope. PMID:25215995

  14. Toward the optical "magic carpet": reducing the divergence of a light sheet below the diffraction limit.

    PubMed

    Golub, Ilya; Chebbi, Brahim; Golub, Jonathan

    2015-11-01

    In 3D, diffraction-free or Bessel beams are well known and have found applications in diverse fields. An analog in 2D, or pseudonondiffracting (PND) beams, is a nontrivial problem, and existing methods suffer from deficiencies. For example, Airy beams are not highly localized, some PND beams have significant side lobes, and a cosine beam has to be truncated by a very narrow aperture thus discarding most of the energy. We show, both theoretically and experimentally, that it is possible to generate a quasi-nondiffracting 2D light beam in a simple and efficient fashion. This is achieved by placing a mask consisting of a pair of double slits on a cylindrical lens. The applications include light sheet microscopy/optical sectioning and particle manipulation. PMID:26512534

  15. Overcoming of the Diffraction Limit for the Discrete Case in Time Reversed Acoustics

    NASA Astrophysics Data System (ADS)

    Velázquez-Arcos, J. M.; Vargas, C. A.; Fernández-Chapou, L.; Granados-Samaniego, J.

    2008-04-01

    The time reversal phenomenon in sound waves for the discrete case is revisited. Our purpose is to improve a previous explanation of this problem in which there was a more limited scope. We develop a formulation which includes sink terms in the time reversed process, which allow going beyond the diffraction limit. By employing a reversed signal it is possible to reach a definition of a fourteenth of the wavelength. In the present work we discuss a matrix formulation for the discrete case in terms of the Fourier transforms of the input and output signals and the Green function. With this function it is possible to characterize the propagation of signals emitted by an array of devices. We are able to express the time reversed signal and precisely select the destination site, among other useful objectives. Finally we show an experimental arrangement using a Michelson interferometer in order to observe this phenomenon. Time Reversal originates from the second order time derivative in the wave equation. This is different from the case of nonlinear behavior in media known as acoustic or electromagnetic inverse scattering. Some of the fields which Time Reversal opens for investigation are the time reversal of a signal by a sound mirror (Time Reversal Mirror or TRM) or by a Time Reversal Cavity (TRC), and the possibility of sending a message to a precise physical location. Recently a new and powerful application has been reported in the literature, namely the abovementioned overcoming of the diffraction limit in wave physics. Although our experimental proposal is based on reports from others authors, the experimental arrangement used here, the specific way of operation and the image construction are original.

  16. Diffraction-limited upgrade to ARGOS: the LBT's ground-layer adaptive optics system

    NASA Astrophysics Data System (ADS)

    Hart, Michael; Busoni, Lorenzo; Durney, Olivier; Esposito, Simone; Gässler, Wolfgang; Gasho, Victor; Rabien, Sebastian; Rademacher, Matt

    2010-07-01

    The Large Binocular Telescope (LBT) is now operating with the first of two permanently installed adaptive secondary mirrors, and the first of two complementary near-IR instruments called LUCIFER is operational as well. The ARGOS laser-guided ground-layer adaptive optics (GLAO) system, described elsewhere at this conference1, will build on this foundation to deliver the highest resolution over the 4 arc min wide-field imaging and multi-object spectroscopic modes of LUCIFER. In this paper, we describe a planned upgrade to ARGOS which will supplement the Rayleigh-based GLAO system with sodium laser guide stars (LGS) to fulfill the telescope's diffraction-limited potential. In its narrow-field mode of 30 arc sec, LUCIFER will deliver imaging at the Nyquist limit of the individual 8.4 m apertures down to J band and long-slit spectroscopy with resolution up to 40,000. In addition, the LBT Interferometer2 (LBTI) will cophase the two apertures, offering imaging at the diffraction limit of the 22.8 m baseline at wavelengths from 1.2 to 20 μm. In the first phase of the upgrade, a 10 W sodium LGS will be added to each half of the LBT, using the same launch telescopes mounted behind the two secondary mirrors as the Rayleigh LGS. The upgrade will rely on other components of the ARGOS infrastructure such as acquisition and guiding, and fast tip-tilt cameras. New wavefront sensors will be added to LUCIFER and LBTI. In the upgrade's second phase, the sodium and Rayleigh LGS will be used together in a hybrid tomographic sensing system. This configuration will offer the advantage that a single tip-tilt star will continue to be sufficient even for MCAO operation3, which is planned with LBT's LINC-NIRVANA instrument4,5.

  17. First results from IRENI - Rapid diffraction-limited high resolution imaging across the mid-infrared bandwidth

    SciTech Connect

    Nasse, Michael J.; Mattson, Eric; Hirschmugl, Carol

    2010-02-03

    First results from IRENI, a new beamline at the Synchrotron Radiation Center, demonstrate that synchrotron chemical imaging, which combines the characteristics of bright, stable, broadband synchrotron source with a multi-element detector, produces diffraction-limited images at all wavelengths simultaneously. A single cell of Micrasterias maintained in a flow cell has been measured, and results show high quality spectra and images demonstrating diffraction limited, and therefore wavelength-dependent, spatial resolution.

  18. Metalenses at visible wavelengths: Diffraction-limited focusing and subwavelength resolution imaging.

    PubMed

    Khorasaninejad, Mohammadreza; Chen, Wei Ting; Devlin, Robert C; Oh, Jaewon; Zhu, Alexander Y; Capasso, Federico

    2016-06-01

    Subwavelength resolution imaging requires high numerical aperture (NA) lenses, which are bulky and expensive. Metasurfaces allow the miniaturization of conventional refractive optics into planar structures. We show that high-aspect-ratio titanium dioxide metasurfaces can be fabricated and designed as metalenses with NA = 0.8. Diffraction-limited focusing is demonstrated at wavelengths of 405, 532, and 660 nm with corresponding efficiencies of 86, 73, and 66%. The metalenses can resolve nanoscale features separated by subwavelength distances and provide magnification as high as 170×, with image qualities comparable to a state-of-the-art commercial objective. Our results firmly establish that metalenses can have widespread applications in laser-based microscopy, imaging, and spectroscopy. PMID:27257251

  19. Optical Imaging of Nonuniform Ferroelectricity and Strain at the Diffraction Limit.

    PubMed

    Vlasin, Ondrej; Casals, Blai; Dix, Nico; Gutiérrez, Diego; Sánchez, Florencio; Herranz, Gervasi

    2015-01-01

    We have imaged optically the spatial distributions of ferroelectricity and piezoelectricity at the diffraction limit. Contributions to the birefringence from electro-optics--linked to ferroelectricity--as well as strain--arising from converse piezoelectric effects--have been recorded simultaneously in a BaTiO3 thin film. The concurrent recording of electro-optic and piezo-optic mappings revealed that, far from the ideal uniformity, the ferroelectric and piezoelectric responses were strikingly inhomogeneous, exhibiting significant fluctuations over the scale of the micrometer. The optical methods here described are appropriate to study the variations of these properties simultaneously, which are of great relevance when ferroelectrics are downscaled to small sizes for applications in data storage and processing. PMID:26522345

  20. Optical Imaging of Nonuniform Ferroelectricity and Strain at the Diffraction Limit

    PubMed Central

    Vlasin, Ondrej; Casals, Blai; Dix, Nico; Gutiérrez, Diego; Sánchez, Florencio; Herranz, Gervasi

    2015-01-01

    We have imaged optically the spatial distributions of ferroelectricity and piezoelectricity at the diffraction limit. Contributions to the birefringence from electro-optics –linked to ferroelectricity– as well as strain –arising from converse piezoelectric effects– have been recorded simultaneously in a BaTiO3 thin film. The concurrent recording of electro-optic and piezo-optic mappings revealed that, far from the ideal uniformity, the ferroelectric and piezoelectric responses were strikingly inhomogeneous, exhibiting significant fluctuations over the scale of the micrometer. The optical methods here described are appropriate to study the variations of these properties simultaneously, which are of great relevance when ferroelectrics are downscaled to small sizes for applications in data storage and processing. PMID:26522345

  1. Three-dimensional array diffraction-limited foci from Greek ladders to generalized Fibonacci sequences.

    PubMed

    Zhang, Junyong

    2015-11-16

    Greek ladder is a technique for approximating Cn by rational numbers where n is a positive integer and C is a positive real number. For the classical Greek ladder, the value isC. Based on the continued fraction theory and algebraic equation, the classical Greek ladder in a special case can be reduced to the generalized Fibonacci sequence. By means of proper switching and binary, ternary or quaternary phase modulation, here we have successfully designed the various kinds of nano-photonic devices to produce three-dimensional array foci whose focusing properties satisfy the above mathematical characteristics. With this technology, the diffraction-limited array foci are freely designed or distributed under the requirement at the desired multiple focal planes. PMID:26698510

  2. Detailed optical characterization of a near diffraction limited xenon fluoride laser

    SciTech Connect

    Londono, C. ); Smith, M.J.; Trainor, D.W.; Itzkan, I. ); Berggren, R. ); Fulghum, S.F. )

    1988-12-01

    A 1 m gain length, electron beam pumped xenon fluoride laser (lambda = 353, 351 nm) utilizing two laser mixtures of lean and rich NF/sub 3/, with Xe and balance Ne, was operated with a confocal unstable resonator with magnification of 2.24. The resultant beam quality was diagnosed with both shearing interferometry to measure near-field phase and far-field focal spot evaluation techniques. These measurements resulted in a beam quality of <1.15 times the diffraction limit with no evidence of the wide angle energy loss. This laser device was fully characterized with regard to electron beam deposition uniformity, transient refractive index effects, and optical quality of the resonator and diagnostic components.

  3. Noninvasive Imaging of 3D Dynamics in Thickly Fluorescent Specimens Beyond the Diffraction Limit

    PubMed Central

    Gao, Liang; Shao, Lin; Higgins, Christopher D.; Poulton, John S.; Peifer, Mark; Davidson, Michael W.; Wu, Xufeng; Goldstein, Bob; Betzig, Eric

    2013-01-01

    SUMMARY Optical imaging of the dynamics of living specimens involves tradeoffs between spatial resolution, temporal resolution, and phototoxicity, made more difficult in three-dimensions. Here, however, we report that rapid 3D dynamics can be studied beyond the diffraction limit in thick or densely fluorescent living specimens over many time points by combining ultra-thin planar illumination produced by scanned Bessel beams with superresolution structured illumination microscopy. We demonstrate in vivo karyotyping of chromosomes during mitosis and identify different dynamics for the actin cytoskeleton at the dorsal and ventral surfaces of fibroblasts. Compared to spinning disk confocal microscopy, we demonstrate substantially reduced photodamage when imaging rapid morphological changes in D. discoideum cells, as well as improved contrast and resolution at depth within developing C. elegans embryos. Bessel beam structured plane illumination thus promises new insights into complex biological phenomena that require 4D subcellular spatiotemporal detail in either a single or multicellular context. PMID:23217717

  4. FRIDA, the diffraction limited NIR imager and IFS for the Gran Telescopio Canarias: status report

    NASA Astrophysics Data System (ADS)

    López, J. A.; Acosta, J.; Alvarez, L. C.; Bringas, V.; Cardiel, N.; Clark, D. M.; Corrales, A.; Cuevas, S.; Chapa, O.; Díaz Garcia, J. J.; Eikenberry, S. S.; Eliche, C.; Espejo, C.; Flores, R.; Fuentes, J.; Gallego, J.; Garcés, J.; Garzón, F.; Hammersley, P.; Keiman, C.; Lara, G.; López, P.; Lucero, D.; Moreno, H.; Pascual, S.; Patrón, J.; Prieto, A.; Rodríguez, A.; Rodríguez, B.; Sánchez, B.; Torres, D.; Uribe, J.; Watson, A.

    2014-07-01

    FRIDA is a diffraction limited imager and integral field spectrometer that is being built for the Gran Telescopio Canarias. FRIDA has been designed and is being built as a collaborative project between institutions from México, Spain and the USA. In imaging mode FRIDA will provide scales of 0.010, 0.020 and 0.040 arcsec/pixel and in IFS mode spectral resolutions R ~ 1000, 4,500 and 30,000. FRIDA is starting systems integration and is scheduled to complete fully integrated system tests at the laboratory by the end of 2015 and be delivered to GTC shortly after. In this contribution we present a summary of its design, fabrication, current status and potential scientific applications.

  5. Metalenses at visible wavelengths: Diffraction-limited focusing and subwavelength resolution imaging

    NASA Astrophysics Data System (ADS)

    Khorasaninejad, Mohammadreza; Chen, Wei Ting; Devlin, Robert C.; Oh, Jaewon; Zhu, Alexander Y.; Capasso, Federico

    2016-06-01

    Subwavelength resolution imaging requires high numerical aperture (NA) lenses, which are bulky and expensive. Metasurfaces allow the miniaturization of conventional refractive optics into planar structures. We show that high-aspect-ratio titanium dioxide metasurfaces can be fabricated and designed as metalenses with NA = 0.8. Diffraction-limited focusing is demonstrated at wavelengths of 405, 532, and 660 nm with corresponding efficiencies of 86, 73, and 66%. The metalenses can resolve nanoscale features separated by subwavelength distances and provide magnification as high as 170×, with image qualities comparable to a state-of-the-art commercial objective. Our results firmly establish that metalenses can have widespread applications in laser-based microscopy, imaging, and spectroscopy.

  6. At-wavelength interferometry of high-NA diffraction-limited EUV optics

    SciTech Connect

    Goldberg, Kenneth A.; Naulleau, Patrick; Rekawa, Senajith; Denham, Paul; Liddle, J. Alexander; Anderson, Erik; Jackson, Keith; Bokor, Jeffrey; Attwood, David

    2003-08-01

    Recent advances in all-reflective diffraction-limited optical systems designed for extreme ultraviolet (EUV) lithography have pushed numerical aperture (NA) values from 0.1 to 0.3, providing Rayleigh resolutions of 27-nm. Worldwide, several high-NA EUV optics are being deployed to serve in the development of advanced lithographic techniques required for EUV lithography, including the creation and testing of new, high-resolution photoresists. One such system is installed on an undulator beamline at Lawrence Berkeley National Laboratory's Advanced Light Source. Sub{angstrom}-accuracy optical testing and alignment techniques, developed for use with the previous generations of EUV lithographic optical systems, are being extended for use at high NA. Considerations for interferometer design and use are discussed.

  7. 400-W near diffraction-limited single-frequency all-solid photonic bandgap fiber amplifier.

    PubMed

    Pulford, Benjamin; Ehrenreich, Thomas; Holten, Roger; Kong, Fanting; Hawkins, Thomas W; Dong, Liang; Dajani, Iyad

    2015-05-15

    An ytterbium-doped large-mode area photonic bandgap fiber is used to demonstrate 400 W of single-frequency output at 1064 nm with excellent beam quality and minimal stimulated Brillouin scattering. The fiber possesses all-solid microstructures embedded in the cladding and a core composed of phosphosilicate with a diameter of ∼50  μm. As the signal power is pushed beyond 450 W, there is degradation in the beam quality due to the modal instability. We briefly discuss techniques to alleviate this problem in future designs. To the best of our knowledge, the 400-W single-frequency near diffraction-limited output far exceeds the current state-of-the-art from such type of fiber amplifier. PMID:26393723

  8. Limited-angle hybrid optical diffraction tomography system with total-variation-minimization-based reconstruction

    NASA Astrophysics Data System (ADS)

    Krauze, Wojciech; Kuś, Arkadiusz; Kujawinska, Malgorzata

    2015-05-01

    The case of diffraction tomography with limited angle of projections is discussed from the algorithmic and experimental points of view. To reconstruct a three-dimensional distribution of refractive index of a micro-object under study, we use a hybrid approach based on the simultaneous algebraic reconstruction technique (SART) enhanced by a compressed sensing reconstruction technique. It enables us to apply the standard computed tomography algorithms (which assume that the rays are traveling in straight lines through the object) for phase data obtained by means of digital holography. We present the results of analysis of a phantom and real objects obtained by applying SART with anisotropic total variation (ATV) minimization. The real data are acquired from an experimental setup based on a Mach-Zehnder interferometer configuration. Also, it is proven that in the case of simulated data, the limited number of projections captured in a limited angular range can be compensated by a higher number of iterations of the algorithm. We also show that the SART + ATV method applied for experimental data gives better results than the data replenishment algorithm.

  9. Chirally-coupled-core Yb-fiber laser delivering 80-fs pulses with diffraction-limited beam quality warranted by a high-dispersion mirror based compressor.

    PubMed

    Chen, Hung-Wen; Sosnowski, Tom; Liu, Chi-Hung; Chen, Li-Jin; Birge, Jonathan R; Galvanauskas, Almantas; Kärtner, Franz X; Chang, Guoqing

    2010-11-22

    We demonstrate a high-energy femtosecond laser system that incorporates two rapidly advancing technologies: chirally-coupled-core large-mode-area Yb-fiber to ensure fundamental-mode operation and high-dispersion mirrors to enable loss-free pulse compression while preserving the diffraction-limited beam quality. Mode-locking is initiated by a saturable absorber mirror and further pulse shortening is achieved by nonlinear polarization evolution. Centered at 1045 nm with 39-MHz repetition rate, the laser emits 25-nJ, positively chirped pulses with 970-mW average power. 6 bounces from double-chirped-mirrors compress these pulses down to 80 fs, close to their transform-limited duration. The loss-free compression gives rise to a diffraction-limited optical beam (M2 = 1.05). PMID:21164816

  10. 40 CFR 450.22 - Effluent limitations reflecting the best available technology economically achievable (BAT).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... limitations reflecting the best available technology economically achievable (BAT). Except as provided in 40 CFR 125.30 through 125.32, any point source subject to this subpart must achieve, at a minimum, the... best available technology economically achievable (BAT). 450.22 Section 450.22 Protection...

  11. 40 CFR 450.22 - Effluent limitations reflecting the best available technology economically achievable (BAT).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Effluent limitations reflecting the best available technology economically achievable (BAT). Except as provided in 40 CFR 125.30 through 125.32, any point source subject to this subpart must achieve, at a... best available technology economically achievable (BAT). 450.22 Section 450.22 Protection...

  12. 40 CFR 450.22 - Effluent limitations reflecting the best available technology economically achievable (BAT).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... limitations reflecting the best available technology economically achievable (BAT). Except as provided in 40 CFR 125.30 through 125.32, any point source subject to this subpart must achieve, at a minimum, the... best available technology economically achievable (BAT). 450.22 Section 450.22 Protection...

  13. 40 CFR 450.22 - Effluent limitations reflecting the best available technology economically achievable (BAT).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Effluent limitations reflecting the best available technology economically achievable (BAT). Except as provided in 40 CFR 125.30 through 125.32, any point source subject to this subpart must achieve, at a... best available technology economically achievable (BAT). 450.22 Section 450.22 Protection...

  14. 40 CFR 450.22 - Effluent limitations reflecting the best available technology economically achievable (BAT).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Effluent limitations reflecting the best available technology economically achievable (BAT). Except as provided in 40 CFR 125.30 through 125.32, any point source subject to this subpart must achieve, at a... best available technology economically achievable (BAT). 450.22 Section 450.22 Protection...

  15. The Adaptive Optics Lucky Imager: Diffraction limited imaging at visible wavelengths with large ground-based telescopes

    NASA Astrophysics Data System (ADS)

    Crass, Jonathan; Mackay, Craig; King, David; Rebolo-López, Rafael; Labadie, Lucas; Puga, Marta; Oscoz, Alejandro; González Escalera, Victor; Pérez Garrido, Antonio; López, Roberto; Pérez-Prieto, Jorge; Rodríguez-Ramos, Luis; Velasco, Sergio; Villó, Isidro

    2015-01-01

    One of the continuing challenges facing astronomers today is the need to obtain ever higher resolution images of the sky. Whether studying nearby crowded fields or distant objects, with increased resolution comes the ability to probe systems in more detail and advance our understanding of the Universe. Obtaining these high-resolution images at visible wavelengths however has previously been limited to the Hubble Space Telescope (HST) due to atmospheric effects limiting the spatial resolution of ground-based telescopes to a fraction of their potential. With HST now having a finite lifespan, it is prudent to investigate other techniques capable of providing these kind of observations from the ground. Maintaining this capability is one of the goals of the Adaptive Optics Lucky Imager (AOLI).Achieving the highest resolutions requires the largest telescope apertures, however, this comes at the cost of increased atmospheric distortion. To overcome these atmospheric effects, there are two main techniques employed today: adaptive optics (AO) and lucky imaging. These techniques individually are unable to provide diffraction limited imaging in the visible on large ground-based telescopes; AO currently only works at infrared wavelengths while lucky imaging reduces in effectiveness on telescopes greater than 2.5 metres in diameter. The limitations of both techniques can be overcome by combing them together to provide diffraction limited imaging at visible wavelengths on the ground.The Adaptive Optics Lucky Imager is being developed as a European collaboration and combines AO and lucky imaging in a dedicated instrument for the first time. Initially for use on the 4.2 metre William Herschel Telescope, AOLI uses a low-order adaptive optics system to reduce the effects of atmospheric turbulence before imaging with a lucky imaging based science detector. The AO system employs a novel type of wavefront sensor, the non-linear Curvature Wavefront Sensor (nlCWFS) which provides

  16. A diffraction-limited scanning system providing broad spectral range for laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Yu, Jiun-Yann; Liao, Chien-Sheng; Zhuo, Zong-Yan; Huang, Chen-Han; Chui, Hsiang-Chen; Chu, Shi-Wei

    2009-11-01

    Diversified research interests in scanning laser microscopy nowadays require broadband capability of the optical system. Although an all-mirror-based optical design with a suitable metallic coating is appropriate for broad-spectrum applications from ultraviolet to terahertz, most researchers prefer lens-based scanning systems despite the drawbacks of a limited spectral range, ghost reflection, and chromatic aberration. One of the main concerns is that the geometrical aberration induced by off-axis incidence on spherical mirrors significantly deteriorates image resolution. Here, we demonstrate a novel geometrical design of a spherical-mirror-based scanning system in which off-axis aberrations, both astigmatism and coma, are compensated to reach diffraction-limited performance. We have numerically simulated and experimentally verified that this scanning system meets the Marechà l condition and provides high Strehl ratio within a 3°×3° scanning area. Moreover, we demonstrate second-harmonic-generation imaging from starch with our new design. A greatly improved resolution compared to the conventional mirror-based system is confirmed. This scanning system will be ideal for high-resolution linear/nonlinear laser scanning microscopy, ophthalmoscopic applications, and precision fabrications.

  17. Characterization of Differential Toll-Like Receptor Responses below the Optical Diffraction Limit**

    PubMed Central

    Aaron, Jesse S.; Carson, Bryan D.; Timlin, Jerilyn A.

    2013-01-01

    Many membrane receptors are recruited to specific cell surface domains to form nanoscale clusters upon ligand activation. This step appears to be necessary to initiate signaling, including pathways in innate immune system activation. However, virulent pathogens such as Yersinia pestis (the causative agent of plague) are known to evade innate immune detection, in contrast to similar microbes (such as E. coli) that elicit a robust response. This disparity has been partly attributed to the structure of lipopolysaccharides (LPS) on the bacterial cell wall, which are recognized by the innate immune receptor TLR4. As such, we hypothesized that nanoscale differences would exist between the spatial clustering of TLR4 upon binding of LPS derived from Y. pestis and E. coli. Although optical imaging can provide exquisite details of the spatial organization of biomolecules, there is a mismatch between the scale at which receptor clustering occurs (<300 nm) and the optical diffraction limit (>400 nm). The last decade has seen the emergence of super-resolution imaging methods that effectively break the optical diffraction barrier to yield truly nanoscale information in intact biological samples. This study reports the first visualizations of TLR4 distributions on intact cells at image resolutions of <30 nm using a novel, dual-color stochastic optical reconstruction microscopy (STORM) technique. This methodology permits distinction between receptors containing bound LPS from those without at the nanoscale. Importantly, we also show that LPS derived from immuno-stimulatory bacteria resulted in significantly higher LPS-TLR4 cluster sizes and a nearly two-fold greater ligand/receptor colocalization as compared to immuno-evading LPS. PMID:22807232

  18. High-resolution diffraction microscopy using the plane-wave field of a nearly diffraction limited focused x-ray beam

    SciTech Connect

    Takahashi, Yukio; Nishino, Yoshinori; Ishikawa, Tetsuya; Tsutsumi, Ryosuke; Kubo, Hideto; Furukawa, Hayato; Mimura, Hidekazu; Matsuyama, Satoshi; Zettsu, Nobuyuki; Matsubara, Eiichiro; Yamauchi, Kazuto

    2009-08-01

    X-ray waves in the center of the beam waist of nearly diffraction limited focused x-ray beams can be considered to have amplitude and phase that are both almost uniform, i.e., they are x-ray plane waves. Here we report the results of an experimental demonstration of high-resolution diffraction microscopy using the x-ray plane wave of the synchrotron x-ray beam focused using Kirkpatrik-Baez mirrors. A silver nanocube with an edge length of {approx}100 nm is illuminated with the x-ray beam focused to a {approx}1 {mu}m spot at 12 keV. A high-contrast symmetric diffraction pattern of the nanocube is observed in the forward far field. An image of the nanocube is successfully reconstructed by an iterative phasing method and its half-period resolution is 3.0 nm. This method does not only dramatically improve the spatial resolution of x-ray microscopy but also is a key technology for realizing single-pulse diffractive imaging using x-ray free-electron lasers.

  19. Novel techniques for detection and imaging of spin related phenomena: Towards sub-diffraction limited resolution

    NASA Astrophysics Data System (ADS)

    Wolfe, Christopher Stuart

    The idea that the spin degree of freedom of particles can be used to store and transport information has revolutionized the data storage industry and inspired a huge amount of research activity. Spin electronics, or spintronics, provides a plethora of potential improvements to conventional charge electronics that include increased functionality and energy efficiency. Scientists studying spintronics will need a multitude of characterization tools to sensitively detect spins in new materials and devices. There are already a handful of powerful techniques to image spin-related phenomena, but each has limitations. Magnetic resonance force microscopy, for example, offers sensitive detection of spin moments that are localized or nearly so but requires a high vacuum, cryogenic environment. Magnetometry based on nitrogen vacancy centers in diamond is a powerful approach, but requires the nitrogen vacancy center to be in very close contact to the spin system being studied to be able to measure the field generated by the system. Spin-polarized scanning tunneling microscopy provides perhaps the best demonstrated spatial resolution, but typically requires ultrahigh vacuum conditions and is limited to studying the surface of a sample. Traditional optical techniques such as Faraday or Kerr microscopy are limited in spatial resolution by the optical diffraction limit. In this dissertation I will present three new techniques we have developed to address some of these issues and to provide the community with new tools to help push forward spintronics and magnetism related research. I will start by presenting the first experimental demonstration of scanned spin-precession microscopy. This technique has the potential to turn any spin-sensitive detection technique into an imaging platform by providing the groundwork for incorporating a magnetic field gradient with that technique, akin to magnetic resonance imaging, and the mathematical tools to analyze the data and extract the local

  20. Electromagnetic energy transport below the diffraction limit in periodic metal nanostructures

    NASA Astrophysics Data System (ADS)

    Maier, Stefan A.; Kik, Pieter G.; Brongersma, Mark L.; Atwater, Harry A.

    2001-12-01

    We investigate the possibility of using arrays of closely spaced metal nanoparticles as waveguides for electromagnetic energy below the diffraction limit of visible light. Coupling between adjacent particles sets up coupled plasmon modes that give rise to coherent propagation of energy along the array. A point dipole analysis predicts group velocities of energy transport that exceed 0.1c along straight arrays and shows that energy transmission through chain networks such as corners and tee structures is possible at high efficiencies. Although radiation losses into the far field are negligible due to the near-field nature of the coupling, resistive heating leads to transmission losses of about 3 dB/500 nm for gold and silver particles. We confirmed the predictions of this analytical model using numeric finite difference time domain (FDTD) simulations. Also, we have fabricated gold nanoparticle arrays using electron beam lithography to study this type of electromagnetic energy transport. A modified illumination near field scanning optical microscope (NSOM) was used as a local excitation source of a nanoparticle in these arrays. Transport is studied by imaging the fluorescence of dye-filled latex beads positioned next to the nanoparticle arrays. We report on initial experiments of this kind.

  1. Advances in design and testing of limited angle optical diffraction tomographysystem for biological applications

    NASA Astrophysics Data System (ADS)

    Kuś, A.; Makowski, P.; Kujawińska, M.

    2016-03-01

    Optical diffraction tomography has been steadily proving its potential to study one of the hot topics in modern cell biology -- 3D dynamic changes in cells' morphology represented with refractive index values. In this technique digital holography is combined with tomographic reconstruction and thus it is necessary to provide projections acquired at different viewing directions. Usually the Mach-Zehnder interferometer configuration is used and while the object beam performs scanning, the reference beam is in most cases stationary. This approach either limits possible scanning strategies or requires additional mechanical movement to be introduced in the reference beam. On the other hand, spiral or grid scanning is possible in alternative common-path or Michelson configurations. However, in this case there is no guarantee that a specimen is sparse enough for the object to interfere with an object-free part of the beam. In this paper we present a modified version of Mach-Zehnder interferometer-based tomographic microscope, in which both object and reference beam are subject to scanning using one scanning device only thus making any scanning scenario possible. This concept is realized with a custom-built optical system in the reference beam and is appropriate for mechanical as well as optical scanning. Usually, the tomographic reconstruction setups and algorithms are verified using a microsphere phantom, which is not enough to test the influence of the distribution of the projections. In this work we propose a more complex calibration object created using two-photon polymerization.

  2. Photonic spatial reformatting of stellar light for diffraction-limited spectroscopy

    NASA Astrophysics Data System (ADS)

    Harris, R. J.; MacLachlan, D. G.; Choudhury, D.; Morris, T. J.; Gendron, E.; Basden, A. G.; Brown, G.; Allington-Smith, J. R.; Thomson, R. R.

    2015-06-01

    The spectral resolution of a dispersive spectrograph is dependent on the width of the entrance slit. This means that astronomical spectrographs trade-off throughput with spectral resolving power. Recently, optical guided-wave transitions known as photonic lanterns have been proposed to circumvent this trade-off, by enabling the efficient reformatting of multimode light into a pseudo-slit which is highly multimode in one axis, but diffraction-limited in the other. Here, we demonstrate the successful reformatting of a telescope point spread function into such a slit using a three-dimensional integrated optical waveguide device, which we name the photonic dicer. Using the CANARY adaptive optics (AO) demonstrator on the William Herschel Telescope, and light centred at 1530 nm with a 160 nm full width at half-maximum, the device shows a transmission of between 10 and 20 per cent depending upon the type of AO correction applied. Most of the loss is due to the overfilling of the input aperture in poor and moderate seeing. Taking this into account, the photonic device itself has a transmission of 57 ± 4 per cent. We show how a fully-optimized device can be used with AO to provide efficient spectroscopy at high spectral resolution.

  3. Searching for Extra-solar Planets with a Diffraction-Limited Balloon Borne Telescope

    NASA Astrophysics Data System (ADS)

    Ford, H. C.; Petro, L. D.; Allen, R.; Bely, P.; Burrows, C. J.; Krist, J.; Rafal, M.; White, R. L.; Jaffe, W.; Le Poole, R.; Crocker, J.; Dopita, M. A.; Grindlay, J. E.

    1998-12-01

    Our goal is to fly a diffraction limited 2.5-m optical telescope and coronagraph on long duration balloon flights at an altitudes of 35 km above 99.99% of the Earth's atmosphere to search for Jupiter-like planets around nearby stars. Analysis of radiosonde data from Mauna Kea and the South Pole suggests that at optical wavelengths and altitudes above 20 km r0 will be much greater than 6 meters anywhere in the world. A telescope equipped with an ultra smooth mirror and/or adaptive optics and coronagraph would provide three orders of magnitude improvement over the coronagraph in the Advanced Camera for Surveys (to be installed in Hubble in May 2000), four orders of magnitude improvement over the HST WFPC-2 camera, and five orders of magnitude improvement over ground based telescopes. A 2.5-m telescope could detect Jupiters and Saturns around the brightest stars within 10 parsecs of the Earth. No present or planned HST instruments will have this capability. Before we can design, build, and fly high resolution telescopes, we must first understand the high altitude balloon environment in detail. We need to know the spatial and temporal spectrum of wavefront errors, and the differential wind forces that will act on the telescope. We must understand the balloon environment sufficiently well to be able to discharge waste heat without spoiling the local thermal environment. We will discuss the major issues for high altitude "site testing" and subsequent high-resolution observations.

  4. Diffraction limited gamma-ray optics using Fresnel lenses for micro-arc second angular resolution

    NASA Astrophysics Data System (ADS)

    Skinner, G.; von Ballmoos, P.; Gehrels, N.; Krzmanic, J.

    2003-03-01

    Refractive indices at gamma-ray wavelengths are such that material thicknesses of the order of millimeters allow the phase of a wavefront to be changed by up to 2π . Thus a phase Fresnel lens can be made from a simple profiled thin disk of, for example, aluminium or plastic. Such a lens can easily have a collecting area of several square meters and an efficiency >90%. Ordinary engineering tolerances allow the manufacture of a lens which can be diffraction limited in the pico-meter wavelength band (up to ˜MeV) and thus provides a simple optical system with angular resolution better than a micro arc second i.e. the resolution necessary to resolve structures on the scale of the event horizon of super-massive black holes in AGN. However the focal length of such a lens is very long - up to a million km. Nevertheless studies have shown that a mission `Fresnel' using a detector and a phase Fresnel lens on two station-keeping spacecraft separated by such a distance is feasible. Results from these studies and work on other proof of concept studies are presented.

  5. Near-diffraction-limited tunable liquid crystal lens with simplified design

    NASA Astrophysics Data System (ADS)

    Li, Liwei; Bryant, Doug; Van Heugten, Tony; Duston, Dwight; Bos, Philip J.

    2013-03-01

    A high-efficiency tunable refractive lens based on liquid crystals with concentric electrode rings and a simple unique design of a resistor network is reported, and used to assess the performance of an optimized electrically tunable lens. It has a large number of phase control points to be able to accurately control the phase profile and produce high efficiency. The lens design uses resistors between neighboring electrodes to minimize external connections. The lens optical path difference is measured as a near perfect parabolic shape and the Strehl ratio of about 80% is obtained (comparing to a high-quality glass lens). Image evaluations show a good image quality with diffraction limited resolution, but the contrast is lowered by a large-area haze. The lens design also shows a good switching speed, and adjustable power, allowing it to be used in many applications. An example lens with a diameter of 2.4 mm and a 5 diopter tunable range is used in the evaluations.

  6. Current status of FRIDA: diffraction limited NIR instrument for the GTC

    NASA Astrophysics Data System (ADS)

    Sánchez, Beatriz; Acosta, José A.; Álvarez, Luis C.; Bringas, Vicente; Cardiel, Nicolás.; Corrales, Adi; Cuevas, Salvador; Chapa, Oscar; Díaz, José Javier; Eikenberry, Stephen S.; Eliche, Carmen; Espejo, Carlos; Flores, Rubén.; Garzón, Francisco; Hammersley, Peter; Keiman, Carolina; Lara, Gerardo; López, José A.; López, Pablo; Lucero, Diana; Montoya, Jose Manuel; Moreno, Heidy; Pascual, Sergio; Patrón, Jesús; Prieto, Almudena; Raines, N.; Rodríguez, Alberto; Uribe, Jorge; Watson, Alan

    2012-09-01

    FRIDA (inFRared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias) is designed as a diffraction limited instrument that will offer broad and narrow band imaging and integral field spectroscopy capabilities with low (R ~ 1,500), intermediate (R ~ 4,500) and high (R ~ 30,000) spectral resolutions to operate in the wavelength range 0.9 - 2.5 μm. The integral field unit is based on a monolithic image slicer. The imaging and IFS observing modes will use the same Teledyne 2K x 2K detector. FRIDA will be based at the Nasmyth B platform of GTC, behind the AO system. The key scientific objectives of the instrument include studies of solar system bodies, low mass objects, circumstellar outflow phenomena in advanced stages of stellar evolution, active galactic nuclei, high redshift galaxies, resolved stellar populations, semi-detached binary systems, young stellar objects and star forming environments. FRIDA is a collaborative project between the main GTC partners, namely, Spain, México and Florida. In this paper, we present the status of the instrument design as it is currently being prepared for its manufacture, after an intensive prototypes' phase and design optimization. The CDR was held in September 2011.

  7. Counselor Trainee Achievement Goal Orientation and the Acquisition of Time-Limited Dynamic Psychotherapy Skills.

    ERIC Educational Resources Information Center

    Kivlighan, Dennis M., Jr.; Schuetz, Steven A.; Kardash, CarolAnne M.

    1998-01-01

    The relationship between trainee achievement goal orientation and acquisition of Time-Limited Dynamic Psychotherapy (TLDP) skills was examined over four counseling sessions with a recruited client. Trainee learning goal orientation was related to the pattern of TLDP skill acquisition. Approaches to achievement goals, results, training issues, and…

  8. The LBT experience of adaptive secondary mirror operations for routine seeing- and diffraction-limited science operations

    NASA Astrophysics Data System (ADS)

    Guerra, J. C.; Brusa, G.; Christou, J.; Miller, D.; Ricardi, A.; Xompero, M.; Briguglio, R.; Wagner, M.; Lefebvre, M.; Sosa, R.

    2013-09-01

    The Large Binocular Telescope (LBT) is unique in that it is currently the only large telescope (2 x 8.4m primary mirrors) with permanently mounted adaptive secondary mirrors (ASMs). These ASMs have been used for regular observing since early 2010 on the right side and since late 2011 on the left side. They are currently regularly used for seeing-limited observing as well as for selective diffraction-limited observing and are required to be fully operational every observing night. By comparison the other telescopes using ASMs, the Multi Mirrot Telescope (MMT) and more recently Magellan, use fixed secondaries of seeing-limited observing and switch in the ASMs for diffraction-limited observing. We will discuss the night-to-night operational requirements for ASMs specifically for seeing-limited but also for diffraction-limited observations based on the LBT experience. These will include preparation procedures for observing (mirror flattening and resting as examples); hardware failure statistics and how to deal with them such as for the actuators; observing protocols for; and current limitations of use due to the ASM technology such as the minimum elevation limit (25 degrees) and the hysteresis of the gravity-vector induced astigmatism. We will also discuss the impact of ASM maintenance and preparation

  9. Diffraction-limited Polarimetry from the Infrared Imaging Magnetograph at Big Bear Solar Observatory

    NASA Astrophysics Data System (ADS)

    Cao, Wenda; Jing, Ju; Ma, Jun; Xu, Yan; Wang, Haimin; Goode, Philip R.

    2006-06-01

    The Infrared Imaging Magnetograph (IRIM) system developed by Big Bear Solar Observatory (BBSO) has been put into preliminary operation. It is one of the first imaging spectropolarimeters working at 1565 nm and is used for the observations of the Sun at its opacity minimum, exposing the deepest photospheric layers. The tandem system, which includes a 4.2 nm interference filter, a unique 0.25 nm birefringent Lyot filter, and a Fabry-Pérot etalon, is capable of providing a bandpass as low as 0.01 nm in a telecentric configuration. A fixed quarter-wave plate and a nematic liquid crystal variable retarder are employed for analyzing the circular polarization of the Zeeman components. The longitudinal magnetic field is measured for the highly Zeeman-sensitive Fe I line at 1564.85 nm (Landé factor g=3). The polarimetric data were taken through a field of view of ~145''×145'' and were recorded by a 1024×1024 pixel, 14 bit HgCdTe CMOS focal plane array camera. Benefiting from the correlation tracking system and a newly developed adaptive optics system, the first imaging polarimetric observations at 1565 nm were made at the diffraction limit on 2005 July 1 using BBSO's 65 cm telescope. After comparing the magnetograms from IRIM with those taken by the Michelson Doppler Imager on board SOHO, it was found that all the magnetic features matched very well in both sets of magnetograms. In addition, Stokes V profiles obtained from the Fabry-Pérot etalon scan data provide access to both the true magnetic field strength and the filling factor of the small-scale magnetic flux elements. In this paper, we present the design, fabrication, and calibration of IRIM, as well as the results of the first scientific observations.

  10. Data reduction pipeline for OSIRIS, the new NIR diffraction-limited imaging field spectrograph for the Keck adaptive optics system

    NASA Astrophysics Data System (ADS)

    Krabbe, Alfred; Gasaway, Tom; Song, Inseok; Iserlohe, Christof; Weiss, Jason; Larkin, James E.; Barczys, Matthew; Lafreniere, David

    2004-09-01

    OSIRIS is a near infrared diffraction limited imaging field spectrograph under development for the Keck observatory adaptive optics system and scheduled for commissioning in fall 2004. Based upon lenslet pupil imaging, diffraction grating, and a 2Kx2K Hawaii2 HgCdTe array, OSIRIS is a highly efficient instrument at the forefront of today's technology. OSIRIS will deliver per readout up to 4096 diffraction limited spectra in a complex interleaved format, requiring new challenges to be met regarding user interaction and data reduction. A data reduction software package is under development, aiming to provide the observer with a facility instrument allowing him to concentrate on science rather than dealing with instrumental as well as telescope and atmosphere related effects. Together with OSIRIS, a pipeline for basic data reduction will be provided for a new Keck instrument for the first time. A status report is presented here together with some aspects of the data reduction pipeline.

  11. Sub-diffraction Limit Localization of Proteins in Volumetric Space Using Bayesian Restoration of Fluorescence Images from Ultrathin Specimens

    PubMed Central

    Wang, Gordon; Smith, Stephen J.

    2012-01-01

    Photon diffraction limits the resolution of conventional light microscopy at the lateral focal plane to 0.61λ/NA (λ = wavelength of light, NA = numerical aperture of the objective) and at the axial plane to 1.4nλ/NA2 (n = refractive index of the imaging medium, 1.51 for oil immersion), which with visible wavelengths and a 1.4NA oil immersion objective is ∼220 nm and ∼600 nm in the lateral plane and axial plane respectively. This volumetric resolution is too large for the proper localization of protein clustering in subcellular structures. Here we combine the newly developed proteomic imaging technique, Array Tomography (AT), with its native 50–100 nm axial resolution achieved by physical sectioning of resin embedded tissue, and a 2D maximum likelihood deconvolution method, based on Bayes' rule, which significantly improves the resolution of protein puncta in the lateral plane to allow accurate and fast computational segmentation and analysis of labeled proteins. The physical sectioning of AT allows tissue specimens to be imaged at the physical optimum of modern high NA plan-apochormatic objectives. This translates to images that have little out of focus light, minimal aberrations and wave-front distortions. Thus, AT is able to provide images with truly invariant point spread functions (PSF), a property critical for accurate deconvolution. We show that AT with deconvolution increases the volumetric analytical fidelity of protein localization by significantly improving the modulation of high spatial frequencies up to and potentially beyond the spatial frequency cut-off of the objective. Moreover, we are able to achieve this improvement with no noticeable introduction of noise or artifacts and arrive at object segmentation and localization accuracies on par with image volumes captured using commercial implementations of super-resolution microscopes. PMID:22956902

  12. Breaking the diffraction-limited resolution barrier in fiber-optical two-photon fluorescence endoscopy by an azimuthally-polarized beam.

    PubMed

    Gu, Min; Kang, Hong; Li, Xiangping

    2014-01-01

    Although fiber-optical two-photon endoscopy has been recognized as a potential high-resolution diagnostic and therapeutic procedure in vivo, its resolution is limited by the optical diffraction nature to a few micrometers due to the low numerical aperture of an endoscopic objective. On the other hand, stimulated emission depletion (STED) achieved by a circularly-polarized vortex beam has been used to break the diffraction-limited resolution barrier in a bulky microscope. It has been a challenge to apply the STED principle to a fiber-optical two-photon endoscope as a circular polarization state cannot be maintained due to the birefringence of a fiber. Here, we demonstrate the first fiber-optical STED two-photon endoscope using an azimuthally-polarized beam directly generated from a double-clad fiber. As such, the diffraction-limited resolution barrier of fiber-optical two-photon endoscopy can be broken by a factor of three. Our new accomplishment has paved a robust way for high-resolution in vivo biomedical studies. PMID:24406685

  13. Breaking the diffraction-limited resolution barrier in fiber-optical two-photon fluorescence endoscopy by an azimuthally-polarized beam

    PubMed Central

    Gu, Min; Kang, Hong; Li, Xiangping

    2014-01-01

    Although fiber-optical two-photon endoscopy has been recognized as a potential high-resolution diagnostic and therapeutic procedure in vivo, its resolution is limited by the optical diffraction nature to a few micrometers due to the low numerical aperture of an endoscopic objective. On the other hand, stimulated emission depletion (STED) achieved by a circularly-polarized vortex beam has been used to break the diffraction-limited resolution barrier in a bulky microscope. It has been a challenge to apply the STED principle to a fiber-optical two-photon endoscope as a circular polarization state cannot be maintained due to the birefringence of a fiber. Here, we demonstrate the first fiber-optical STED two-photon endoscope using an azimuthally-polarized beam directly generated from a double-clad fiber. As such, the diffraction-limited resolution barrier of fiber-optical two-photon endoscopy can be broken by a factor of three. Our new accomplishment has paved a robust way for high-resolution in vivo biomedical studies. PMID:24406685

  14. Tapered lasers emitting at 650 nm with 1 W output power with nearly diffraction-limited beam quality.

    PubMed

    Adamiec, Pawel; Sumpf, Bernd; Rüdiger, Ingo; Fricke, Jörg; Hasler, Karl-Heinz; Ressel, Peter; Wenzel, Hans; Zorn, Martin; Erbert, Götz; Tränkle, Günther

    2009-08-15

    High-brightness tapered lasers emitting around 650 nm were developed. Devices 2 mm long with a200-microm-long straight section, 1800-microm-long tapered section, and 4 degrees taper angle reached 1 W output power in CW operation with a nearly diffraction-limited beam quality. PMID:19684814

  15. High power, diffraction limited picosecond oscillator based on Nd:GdVO4 bulk crystal with σ polarized in-band pumping.

    PubMed

    Lin, Hua; Guo, Jie; Gao, Peng; Yu, Hai; Liang, Xiaoyan

    2016-06-27

    We report on a high power passively mode-locked picosecond oscillator based on Nd:GdVO4 crystal with σ polarized in-band pumping. Thermal gradient and thermal aberration was greatly decreased with proposed configuration. Maximum output power of 37 W at 81 MHz repetition rate with 19.3 ps pulse duration was achieved directly from Nd:GdVO4 oscillator, corresponding to 51% optical efficiency. The oscillator maintained diffraction limited beam quality of M2 < 1.05 at different output coupling with pulse duration between 11.2 ps to 19.3 ps. PMID:27410558

  16. Estimating the Impact of the Massachusetts English Immersion Law on Limited English Proficient Students' Reading Achievement

    ERIC Educational Resources Information Center

    Guo, Qian; Koretz, Daniel

    2013-01-01

    The large number of limited English proficient (LEP) children in U.S. schools and the uncertainty about the impact of bilingual education versus English immersion on their achievement warrant rigorous investigation of the effects of "English immersion laws." We estimated the impact of "Question 2", the Massachusetts English immersion law, and…

  17. Understanding Possibilities and Limitations of Abstract Chemical Representations for Achieving Conceptual Understanding

    ERIC Educational Resources Information Center

    Corradi, David M. J.; Elen, Jan; Schraepen, Beno; Clarebout, Geraldine

    2014-01-01

    When learning with abstract and scientific multiple external representations (MERs), low prior knowledge learners are said to have difficulties in using these MERs to achieve conceptual understanding. Yet little is known about what these limitations precisely entail. In order to understand this, we presented 101 learners with low prior knowledge…

  18. Getting lucky with adaptive optics: diffraction-limited resolution in the visible with current AO systems on large and small telescopes

    NASA Astrophysics Data System (ADS)

    Law, N. M.; Dekany, R. G.; Mackay, C. D.; Moore, A. M.; Britton, M. C.; Velur, V.

    2008-07-01

    We have recently demonstrated diffraction-limited resolution imaging in the visible on the 5m Palomar Hale telescope. The new LAMP instrument is a Lucky Imaging backend camera for the Palomar AO system. Typical resolutions of 35-40 mas with Strehls of 10-20% were achieved at 700nm, and at 500nm the FWHM resolution was as small as 42 milliarcseconds. In this paper we discuss the capabilities and design challenges of such a system used with current and near future AO systems on a variety of telescopes. In particular, we describe the designs of two planned Lucky Imaging + AO instruments: a facility instrument for the Palomar 200" AO system and its PALM3K upgrade, and a visible-light imager for the CAMERA low-cost LGS AO system planned for the Palomar 60" telescope. We introduce a Monte Carlo simulation setup that reproduces the observed PSF variability behind an adaptive optics system, and apply it to predict the performance of 888Cam and CAMERA. CAMERA is predicted to achieve diffraction-limited resolution at wavelengths as short as 350 nm. In addition to on-axis resolution improvements we discuss the results of frame selection with the aim of improving other image parameters such as isoplanatic patch sizes, showing that useful improvements in image quality can be made by Lucky+AO even with very temporally and spatially undersampled data.

  19. Super-resolving quantum radar: Coherent-state sources with homodyne detection suffice to beat the diffraction limit

    SciTech Connect

    Jiang, Kebei; Lee, Hwang; Gerry, Christopher C.; Dowling, Jonathan P.

    2013-11-21

    There has been much recent interest in quantum metrology for applications to sub-Raleigh ranging and remote sensing such as in quantum radar. For quantum radar, atmospheric absorption and diffraction rapidly degrades any actively transmitted quantum states of light, such as N00N states, so that for this high-loss regime the optimal strategy is to transmit coherent states of light, which suffer no worse loss than the linear Beer's law for classical radar attenuation, and which provide sensitivity at the shot-noise limit in the returned power. We show that coherent radar radiation sources, coupled with a quantum homodyne detection scheme, provide both longitudinal and angular super-resolution much below the Rayleigh diffraction limit, with sensitivity at shot-noise in terms of the detected photon power. Our approach provides a template for the development of a complete super-resolving quantum radar system with currently available technology.

  20. CLASSICAL AREAS OF PHENOMENOLOGY: Below-diffract ion-limited hybrid recording using silicon thin film super-resolution structure

    NASA Astrophysics Data System (ADS)

    Jiao, Xin-Bing; Wei, Jing-Song; Gan, Fu-Xi

    2009-12-01

    We report on new experimental results for below-diffraction-limited hybrid recording. In our experiments, by means of focused laser assisted magnetic recording, the magnetic domains within TbFeCo thin films are obtained under an external perpendicular direct magnetic field. For a single magnetic medium, the domain size is mainly determined by the focused spot, which is about 620 nm for the laser wavelength λ = 406 nm, and a numerical aperture of the lens of 0.80. However, when a silicon thin film structure is inserted between the substrate and the magnetic medium, the recording domains can be reduced obviously. By optimizing the experimental condition, even the size can be reduced to about 100 nm, which is below the diffraction limit, i.e. about 1/6 of the spot size. This is very useful for improving the hybrid recording density in practical applications.

  1. Throughput of diffraction-limited field optics systems for infrared and millimetric telscopes

    SciTech Connect

    Hildebrand, R.H.; Winston, R.

    1982-05-15

    Telescopes for submillimeter wavelengths have point spread functions some millimeters or centimeters in diameter, but the detectors may be only fractions of a millimeter in size. Thus a field aperture and collecting optics are needed. We show how to optimize the aperture by a calculation of the effects of diffraction on signal and resolution as a function of size of the collecting aperture. Our calculations are compared to experimental results from observations of Mars at submillimeter wavelengths.

  2. Prospects of high-resolution resonant X-ray inelastic scattering studies on solid materials, liquids and gases at diffraction-limited storage rings

    PubMed Central

    Schmitt, Thorsten; de Groot, Frank M. F.; Rubensson, Jan-Erik

    2014-01-01

    The spectroscopic technique of resonant inelastic X-ray scattering (RIXS) will particularly profit from immensely improved brilliance of diffraction-limited storage rings (DLSRs). In RIXS one measures the intensities of excitations as a function of energy and momentum transfer. DLSRs will allow for pushing the achievable energy resolution, signal intensity and the sampled spot size to new limits. With RIXS one nowadays probes a broad range of electronic systems reaching from simple molecules to complex materials displaying phenomena like peculiar magnetism, two-dimensional electron gases, superconductivity, photovoltaic energy conversion and heterogeneous catalysis. In this article the types of improved RIXS studies that will become possible with X-ray beams from DLSRs are envisioned. PMID:25177995

  3. Conventional fluorescence microscopy below the diffraction limit with simultaneous capture of two fluorophores in DNA origami

    NASA Astrophysics Data System (ADS)

    Glasgow, Ben J.

    2016-02-01

    A conventional fluorescence microscope was previously constructed for simultaneous imaging of two colors to gain sub-diffraction localization. The system is predicated on color separation of overlapping Airy discs, construction of matrices of Cartesian coordinates to determine locations as well as centers of the point spread functions of fluorophores. Quantum dots that are separated by as little as 10 nm were resolved in the x-y coordinates. Inter-fluorophore distances that vary by 10 nm could also be distinguished. Quantum dots are bright point light source emitters that excite with a single laser and can serve as a label for many biomolecules. Here, alterations in the method are described to test the ability to resolve Atto 488 and Atto 647 dyes attached to DNA origami at ~40 nm spacing intervals. Dual laser excitation is used in tandem with multi-wavelength bandpass filters. Notwithstanding challenges from reduced intensity in Atto labeled DNA origami helical bundles compared to quantum dots, preliminary data show a mean inter-fluorophore distance of 56 nm with a range (14-148 nm). The range closely matches published results with DNA origami with other methods of subdiffraction microscopy. Sub-diffraction simultaneous two-color imaging fluorescence microscopy acronymically christened (SSTIFM) is a simple, readily accessible, technique for measurement of inter-fluorophore distances in compartments less than 40 nm. Preliminary results with so called nanorulers are encouraging for use with other biomolecules.

  4. Data Reduction Pipeline for OSIRIS, the new NIR Diffraction Limited Imaging Field Spectrometer for the Keck Adaptive Optics System

    NASA Astrophysics Data System (ADS)

    Krabbe, Alfred; Gasaway, Thomas M.; Weiss, Jason; Larkin, James E.; Barczys, Matthew; Quirrenbach, Andreas; LaFreniere, David

    2002-12-01

    OSIRIS is a near infrared diffraction limited imaging field spectrometer under development for the Keck observatory adaptive optics system. Based upon lenslet pupil imaging, diffraction grating, and a 2K×2K Hawaii2 HgCdTe array, OSIRIS is a highly efficient instrument at the forefront of today"s technology. OSIRIS will deliver per readout up to 4096 diffraction limited spectra in a complex interleaved format, requiring new challenges to be met regarding user interaction and data reduction. A data reduction software package is under development, aiming to provide the observer with a facility instrument allowing him to concentrate on science rather than dealing with instrumental as well as telescope and atmosphere related effects. Together with OSIRIS, a pipeline for basic data reduction will be provided for a new Keck instrument for the first time. Some aspects of the data reduction pipeline will be presented here. The OSIRIS instrument as such, the astronomical background as well as other software tools were presented elsewhere on this conference.

  5. Optically confined polarized resonance Raman studies in identifying crystalline orientation of sub-diffraction limited AlGaN nanostructure

    SciTech Connect

    Sivadasan, A. K. Patsha, Avinash; Dhara, Sandip

    2015-04-27

    An optical characterization tool of Raman spectroscopy with extremely weak scattering cross section tool is not popular to analyze scattered signal from a single nanostructure in the sub-diffraction regime. In this regard, plasmonic assisted characterization tools are only relevant in spectroscopic studies of nanoscale object in the sub-diffraction limit. We have reported polarized resonance Raman spectroscopic (RRS) studies with strong electron-phonon coupling to understand the crystalline orientation of a single AlGaN nanowire of diameter ∼100 nm. AlGaN nanowire is grown by chemical vapor deposition technique using the catalyst assisted vapor-liquid-solid process. The results are compared with the high resolution transmission electron microscopic analysis. As a matter of fact, optical confinement effect due to the dielectric contrast of nanowire with respect to that of surrounding media assisted with electron-phonon coupling of RRS is useful for the spectroscopic analysis in the sub-diffraction limit of 325 nm (λ/2N.A.) using an excitation wavelength (λ) of 325 nm and near ultraviolet 40× far field objective with a numerical aperture (N.A.) value of 0.50.

  6. Diffracted and pseudo-physical waves from spatially limited arrays using source-receiver interferometry (SRI)

    NASA Astrophysics Data System (ADS)

    Löer, Katrin; Meles, Giovanni Angelo; Curtis, Andrew; Vasconcelos, Ivan

    2014-02-01

    Source-receiver interferometry (SRI) refers to a technique to construct the Green's function between a source and a receiver using only energy that has travelled from and to surrounding boundaries of sources and receivers. If a background medium is perturbed, the corresponding interferometric equation can be expressed as the sum of eight terms, which result from the separation of the total wavefield into an unperturbed background field and the perturbed scattered field. Here, the contribution of each individual term is identified for singly diffracted waves using the methods of stationary phase analysis and waveform modelling. When the data acquisition boundary requirements for seismic interferometry are violated, non-physical energy is introduced into Green's function estimates. Our results show that four terms produce purely non-physical, non-stationary energy and that these can be suppressed, and that a combination of only two terms can be used to estimate diffracted wavefields robustly. One of the two terms is precisely that used in geophysical imaging schemes. A key result is that this term also produces non-physical energy, except when the integration boundaries are truncated to span only part of the medium's free surface: we thus show that in this sense, partial boundaries can be seen as a positive advantage for migration or imaging methods. The other term produces non-physical energy which nevertheless emulates physical energy; such energy is therefore called pseudo-physical. We present for the first time a complete mathematical derivation of this new category of energy complemented with illustrative examples. Overall, this work significantly enhances our understanding of how scattered wave SRI works.

  7. High resolution imaging beyond the acoustic diffraction limit in deep tissue via ultrasound-switchable NIR fluorescence

    NASA Astrophysics Data System (ADS)

    Pei, Yanbo; Wei, Ming-Yuan; Cheng, Bingbing; Liu, Yuan; Xie, Zhiwei; Nguyen, Kytai; Yuan, Baohong

    2014-04-01

    Fluorescence imaging in deep tissue with high spatial resolution is highly desirable because it can provide details about tissue's structural, functional, and molecular information. Unfortunately, current fluorescence imaging techniques are limited either in penetration depth (microscopy) or spatial resolution (diffuse light based imaging) as a result of strong light scattering in deep tissue. To overcome this limitation, we developed an ultrasound-switchable fluorescence (USF) imaging technique whereby ultrasound was used to switch on/off the emission of near infrared (NIR) fluorophores. We synthesized and characterized unique NIR USF contrast agents. The excellent switching properties of these agents, combined with the sensitive USF imaging system developed in this study, enabled us to image fluorescent targets in deep tissue with spatial resolution beyond the acoustic diffraction limit.

  8. 1.89 kW all-fiberized and polarization-maintained amplifiers with narrow linewidth and near-diffraction-limited beam quality.

    PubMed

    Ma, Pengfei; Tao, Rumao; Su, Rongtao; Wang, Xiaolin; Zhou, Pu; Liu, Zejin

    2016-02-22

    In this manuscript, we demonstrate high power, all-fiberized and polarization-maintained amplifiers with narrow linewidth and near-diffraction-limited beam quality by simultaneously suppressing detrimental stimulated Brillouin scattering (SBS) and mode instability (MI) effects. Compared with strictly single frequency amplification, the SBS threshold is scaled up to 12 dB, 15.4 dB, and higher than 18 dB by subsequently using three-stage cascaded phase modulation systems. Output powers of 477 W, 1040 W, and 1890 W are achieved with full widths at half maximums (FWHMs) of within 6 GHz, ~18.5 GHz, and ~45 GHz, respectively. The MI threshold is increased from ~738 W to 1890 W by coiling the active fiber in the main amplifier. Both the polarization extinction ratio (PER) and beam quality (M2 factor) are maintained well during the power scaling process. To the best of our knowledge, this is the first demonstration of all-fiberized amplifiers with narrow linewidth, near linear polarization, and near-diffraction-limited beam quality at 2 kW power-level. PMID:26907067

  9. OBSERVATIONS OF BINARY STARS WITH THE DIFFERENTIAL SPECKLE SURVEY INSTRUMENT. III. MEASURES BELOW THE DIFFRACTION LIMIT OF THE WIYN TELESCOPE

    SciTech Connect

    Horch, Elliott P.; Van Altena, William F.; Howell, Steve B.; Sherry, William H.; Ciardi, David R. E-mail: william.vanaltena@yale.edu E-mail: wsherry@noao.edu

    2011-06-15

    In this paper, we study the ability of CCD- and electron-multiplying-CCD-based speckle imaging to obtain reliable astrometry and photometry of binary stars below the diffraction limit of the WIYN 3.5 m Telescope. We present a total of 120 measures of binary stars, 75 of which are below the diffraction limit. The measures are divided into two groups that have different measurement accuracy and precision. The first group is composed of standard speckle observations, that is, a sequence of speckle images taken in a single filter, while the second group consists of paired observations where the two observations are taken on the same observing run and in different filters. The more recent paired observations were taken simultaneously with the Differential Speckle Survey Instrument, which is a two-channel speckle imaging system. In comparing our results to the ephemeris positions of binaries with known orbits, we find that paired observations provide the opportunity to identify cases of systematic error in separation below the diffraction limit and after removing these from consideration, we obtain a linear measurement uncertainty of 3-4 mas. However, if observations are unpaired or if two observations taken in the same filter are paired, it becomes harder to identify cases of systematic error, presumably because the largest source of this error is residual atmospheric dispersion, which is color dependent. When observations are unpaired, we find that it is unwise to report separations below approximately 20 mas, as these are most susceptible to this effect. Using the final results obtained, we are able to update two older orbits in the literature and present preliminary orbits for three systems that were discovered by Hipparcos.

  10. Conventional fluorescence microscopy below the diffraction limit with simultaneous capture of two fluorophores in DNA origami

    PubMed Central

    2016-01-01

    A conventional fluorescence microscope was previously constructed for simultaneous imaging of two colors to gain subdiffraction localization. The system is predicated on color separation of overlapping Airy discs, construction of matrices of Cartesian coordinates to determine locations as well as centers of the point spread functions of fluorophores. Quantum dots that are separated by as little as 10 nm were resolved in the x-y coordinates. Inter-fluorophore distances that vary by 10 nm could also be distinguished. Quantum dots are bright point light source emitters that excite with a single laser and can serve as a label for many biomolecules. Here, alterations in the method are described to test the ability to resolve Atto 488 and Atto 647 dyes attached to DNA origami at ~40 nm spacing intervals. Dual laser excitation is used in tandem with multi-wavelength bandpass filters. Notwithstanding challenges from reduced intensity in Atto labeled DNA origami helical bundles compared to quantum dots, preliminary data show a mean inter-fluorophore distance of 56 nm with a range (14-148 nm). The range closely matches published results with DNA origami with other methods of subdiffraction microscopy. Sub-diffraction simultaneous two-color imaging fluorescence microscopy acronymically christened (SSTIFM) is a simple, readily accessible, technique for measurement of inter-fluorophore distances in compartments less than 40 nm. Preliminary results with so called nanorulers are encouraging for use with other biomolecules. PMID:27307653

  11. Spatially dependent Rabi oscillations: An approach to sub-diffraction-limited coherent anti-Stokes Raman-scattering microscopy

    SciTech Connect

    Beeker, Willem P.; Lee, Chris J.; Boller, Klaus-Jochen; Gross, Petra; Cleff, Carsten; Fallnich, Carsten; Offerhaus, Herman L.; Herek, Jennifer L.

    2010-01-15

    We present a theoretical investigation of coherent anti-Stokes Raman scattering (CARS) that is modulated by periodically depleting the ground-state population through Rabi oscillations driven by an additional control laser. We find that such a process generates optical sidebands in the CARS spectrum and that the frequency of the sidebands depends on the intensity of the control laser light field. We show that analyzing the sideband frequency upon scanning the beams across the sample allows one to spatially resolve emitter positions where a spatial resolution of 65 nm, which is well below the diffraction limit, can be obtained.

  12. Breaking the acoustic diffraction limit via nonlinear effect and thermal confinement for potential deep-tissue high-resolution imaging

    PubMed Central

    Yuan, Baohong; Pei, Yanbo; Kandukuri, Jayanth

    2013-01-01

    Our recently developed ultrasound-switchable fluorescence (USF) imaging technique showed that it was feasible to conduct high-resolution fluorescence imaging in a centimeter-deep turbid medium. Because the spatial resolution of this technique highly depends on the ultrasound-induced temperature focal size (UTFS), minimization of UTFS becomes important for further improving the spatial resolution USF technique. In this study, we found that UTFS can be significantly reduced below the diffraction-limited acoustic intensity focal size via nonlinear acoustic effects and thermal confinement by appropriately controlling ultrasound power and exposure time, which can be potentially used for deep-tissue high-resolution imaging. PMID:23479498

  13. Numerical optimization of integrating cavities for diffraction-limited millimeter-wave bolometer arrays.

    PubMed

    Glenn, Jason; Chattopadhyay, Goutam; Edgington, Samantha F; Lange, Andrew E; Bock, James J; Mauskopf, Philip D; Lee, Adrian T

    2002-01-01

    Far-infrared to millimeter-wave bolometers designed to make astronomical observations are typically encased in integrating cavities at the termination of feedhorns or Winston cones. This photometer combination maximizes absorption of radiation, enables the absorber area to be minimized, and controls the directivity of absorption, thereby reducing susceptibility to stray light. In the next decade, arrays of hundreds of silicon nitride micromesh bolometers with planar architectures will be used in ground-based, suborbital, and orbital platforms for astronomy. The optimization of integrating cavity designs is required for achieving the highest possible sensitivity for these arrays. We report numerical simulations of the electromagnetic fields in integrating cavities with an infinite plane-parallel geometry formed by a solid reflecting backshort and the back surface of a feedhorn array block. Performance of this architecture for the bolometer array camera (Bolocam) for cosmology at a frequency of 214 GHz is investigated. We explore the sensitivity of absorption efficiency to absorber impedance and backshort location and the magnitude of leakage from cavities. The simulations are compared with experimental data from a room-temperature scale model and with the performance of Bolocam at a temperature of 300 mK. The main results of the simulations for Bolocam-type cavities are that (1) monochromatic absorptions as high as 95% are achievable with <1% cross talk between neighboring cavities, (2) the optimum absorber impedances are 400 ohms/sq, but with a broad maximum from approximately 150 to approximately 700 ohms/sq, and (3) maximum absorption is achieved with absorber diameters > or = 1.5 lambda. Good general agreement between the simulations and the experiments was found. PMID:11900429

  14. DBR tapered diode laser at 1030 nm with nearly diffraction-limited narrowband emission and 12.7 W of optical output power

    NASA Astrophysics Data System (ADS)

    Müller, André; Fricke, Jörg; Bugge, Frank; Brox, Olaf; Erbert, Götz; Sumpf, Bernd

    2016-03-01

    Nearly diffraction-limited emission from a distributed Bragg reflector (DBR) tapered diode laser is presented. Intrinsic wavelength stabilization is achieved with a 3rd order DBR grating manufactured by electron beam lithography. At a heatsink temperature of 15°C an optical output power of 12.7 W with an electro-optical efficiency > 40% is obtained. The corresponding emission wavelength is 1030.57 nm and spectral bandwidths of 0.02 nm are measured over the whole power range. At 10.5 W of optical power 8.1 W are contained in the central lobe. The measured beam propagation ratio and brightness are 1.1 (1/e2) and 700 MWcm-2 sr-1, respectively. With these parameters, the laser is suitable for applications such as non-linear frequency conversion.

  15. Efficient concept for generation of diffraction-limited green light by sum-frequency generation of spectrally combined tapered diode lasers.

    PubMed

    Müller, André; Jensen, Ole Bjarlin; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael

    2012-09-15

    In order to increase the power of visible diode laser systems in an efficient manner, we propose spectral beam combining with subsequent sum-frequency generation. We show that this approach, in comparison with second harmonic generation of single emitters, can enhance the available power significantly. By combining two distributed Bragg reflector tapered diode lasers we achieve a 2.5-3.2 fold increase in power and a maximum of 3.9 W of diffraction-limited green light. At this power level, green diode laser systems have a high application potential, e.g., within the biomedical field. Our concept can be expanded combining multiple diode lasers to increase the power even further. PMID:23041848

  16. Ultra-broadband unidirectional launching of surface plasmon polaritons by a double-slit structure beyond the diffraction limit.

    PubMed

    Chen, Jianjun; Sun, Chengwei; Li, Hongyun; Gong, Qihuang

    2014-11-21

    Surface-plasmon-polariton (SPP) launchers, which can couple the free space light to the SPPs on the metal surface, are among the key elements for the plasmonic devices and nano-photonic systems. Downscaling the SPP launchers below the diffraction limit and directly delivering the SPPs to the desired subwavelength plasmonic waveguides are of importance for high-integration plasmonic circuits. By designing a submicron double-slit structure with different slit widths, an ultra-broadband (>330 nm) unidirectional SPP launcher is realized theoretically and experimentally based on the different phase delays of SPPs propagating along the metal surface and the near-field interfering effect. More importantly, the broadband and unidirectional properties of the SPP launcher are still maintained when the slit length is reduced to a subwavelength scale. This can make the launcher occupy only a very small area of <λ(2)/10 on the metal surface. Such a robust unidirectional SPP launcher beyond the diffraction limit can be directly coupled to a subwavelength plasmonic waveguide efficiently, leading to an ultra-tight SPP source, especially as a subwavelength localized guided SPP source. PMID:25204379

  17. Diffraction limit of the theory of multiple small-angle neutron scattering by a dense system of scatterers

    NASA Astrophysics Data System (ADS)

    Dzheparov, F. S.; Lvov, D. V.

    2016-02-01

    Multiple small-angle neutron scattering by a high-density system of inhomogeneities has been considered. A combined approach to the analysis of multiple small-angle neutron scattering has been proposed on the basis of the synthesis of the Zernike-Prince and Moliére formulas. This approach has been compared to the existing multiple small-angle neutron scattering theory based on the eikonal approximation. This comparison has shown that the results in the diffraction limit coincide, whereas differences exist in the refraction limit because the latter theory includes correlations between successive scattering events. It has been shown analytically that the existence of correlations in the spatial position of scatterers results in an increase in the number of unscattered neutrons. Thus, the narrowing of spectra of multiple small-angle neutron scattering observed experimentally and in numerical simulation has been explained.

  18. Localization of atomic excitation beyond the diffraction limit using electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Miles, J. A.; Das, Diptaranjan; Simmons, Z. J.; Yavuz, D. D.

    2015-09-01

    We experimentally demonstrate the localization of excitation between hyperfine ground states of 87Rb atoms to as small as λ /13 -wide spatial regions. We use ultracold atoms trapped in a dipole trap and utilize electromagnetically induced transparency (EIT) for the atomic excitation. The localization is achieved by combining a spatially varying coupling laser (standing wave) with the intensity dependence of EIT. The excitation is fast (150 ns laser pulses) and the dark-state fidelity can be made higher than 94% throughout the standing wave. Because the width of the localized regions is much smaller than the wavelength of the driving light, traditional optical imaging techniques cannot resolve the localized features. Therefore, to measure the excitation profile, we use an autocorrelation-like method where we perform two EIT sequences separated by a time delay, during which we move the standing wave.

  19. Review: Balancing Limiting Factors and Economic Drivers to Achieve Sustainable Midwestern US Agricultural Residue Feedstock Supplies

    SciTech Connect

    Wally W. Wilhelm; J. Richard Hess; Douglas L. Karlen; David J. Muth; Jane M. F. Johnson; John M. Baker; Hero T. Gollany; Jeff M. Novak; Diane E. Stott; Gary E. Varvel

    2010-10-01

    Advanced biofuels will be developed using cellulosic feedstock rather than grain or oilseed crops that can also be used for food and feed. To be sustainable, these new agronomic production systems must be economically viable without degrading soil resources. This review examines six agronomic factors that collectively define many of the limits and opportunities for harvesting crop residue for biofuel feedstock. These six “limiting factors” are discussed in relationship to economic drivers associated with harvesting corn (Zea mays L.) stover as a potential cellulosic feedstock. The limiting factors include soil organic carbon, wind and water erosion, plant nutrient balance, soil water and temperature dynamics, soil compaction, and off-site environmental impacts. Initial evaluations using the Revised Universal Soil Loss Equation 2.0 (RUSLE2) show that a single factor analysis based on simply meeting tolerable soil loss might indicate stover could be harvested sustainably, but the same analysis based on maintaining soil organic carbon shows the practice to be non-sustainable. Modifying agricultural management to include either annual or perennial cover crops is shown to meet both soil erosion and soil carbon requirements. The importance of achieving high yields and planning in a holistic manner at the landscape scale are also shown to be crucial for balancing limitations and drivers associated with renewable bioenergy production.

  20. Overcoming the diffraction limit of imaging nanoplasmonic arrays by microspheres and microfibers.

    PubMed

    Allen, Kenneth W; Farahi, Navid; Li, Yangcheng; Limberopoulos, Nicholaos I; Walker, Dennis E; Urbas, Augustine M; Astratov, Vasily N

    2015-09-21

    Super-resolution microscopy by microspheres emerged as a simple and broadband imaging technique; however, the mechanisms of imaging are debated in the literature. Furthermore, the resolution values were estimated based on semi-quantitative criteria. The primary goals of this work are threefold: i) to quantify the spatial resolution provided by this method, ii) to compare the resolution of nanoplasmonic structures formed by different metals, and iii) to understand the imaging provided by microfibers. To this end, arrays of Au and Al nanoplasmonic dimers with very similar geometry were imaged using confocal laser scanning microscopy at λ = 405 nm through high-index (n~1.9-2.2) liquid-immersed BaTiO3 microspheres and through etched silica microfibers. We developed a treatment of super-resolved images in label-free microscopy based on using point-spread functions with subdiffraction-limited widths. It is applicable to objects with arbitrary shapes and can be viewed as an integral form of the super-resolution quantification widely accepted in fluorescent microscopy. In the case of imaging through microspheres, the resolution ~λ/6-λ/7 is demonstrated for Au and Al nanoplasmonic arrays. In the case of imaging through microfibers, the resolution ~λ/6 with magnification M~2.1 is demonstrated in the direction perpendicular to the fiber with hundreds of times larger field-of-view in comparison to microspheres. PMID:26406653

  1. Plasmonics: Electromagnetic energy transfer and switching in nanoparticle chain-arrays below the diffraction limit

    NASA Astrophysics Data System (ADS)

    Brongersma, Mark; Hartman, John; Atwater, Harry

    2000-03-01

    Integrated optics faces the fundamental limitation that, for the guiding, modulation, and amplification of light, structures are needed that have dimensions comparable to the wavelength of light. Recently, it was theoretically shown that this problem can be circumvented by transporting electromagnetic energy along linear chains of closely spaced metal nanoparticles. This transport relies on the near-field electrodynamic interaction between metal particles that sets up coupled plasmon modes. We have modeled the transport properties of corners, T's, and switches that consist of chains of metal nanoparticles. It is shown that propagation is coherent and the group velocities can exceed saturated velocities of electrons in semiconductors ( ~ 105 m/s). High efficiency transmission of energy around sharp corners (bending radius << wavelength of visible light) is possible. The transmission is a strong function of the frequency and polarization direction of the plasmon mode. Finally, the operation of a plasmon switch is modeled in which plasmon waves can be switched. Suggestions are given for the choice of metal particle and host material. These "plasmonic devices" potentially are among the smallest structures with optical functionality.

  2. Taking X-ray Diffraction to the Limit: Macromolecular Structures from Femtosecond X-ray Pulses and Diffraction Microscopy of Cells with Synchrotron Radiation

    SciTech Connect

    Chapman, H N; Miao, J; Kirz, J; Sayre, D; Hodgson, K O

    2003-10-01

    The methodology of X-ray crystallography has recently been successfully extended to the structure determination of non-crystalline specimens. The phase problem was solved by using the oversampling method, which takes advantage of ''continuous'' diffraction pattern from non-crystalline specimens. Here we review the principle of this newly developed technique and discuss the ongoing experiments of imaging non-periodic objects, like cells and cellular structures using coherent and bright X-rays from the 3rd generation synchrotron radiation. In the longer run, the technique may be applied to image single biomolecules by using the anticipated X-ray free electron lasers. Computer simulations have so far demonstrated two important steps: (1) by using an extremely intense femtosecond X-ray pulse, a diffraction pattern can be recorded from a macromolecule before radiation damage manifests itself, and (2) the phase information can be ab initio retrieved from a set of calculated noisy diffraction patterns of single protein molecules.

  3. Formation of crownlike and related nanostructures on thin supported gold films irradiated by single diffraction-limited nanosecond laser pulses.

    PubMed

    Kulchin, Yu N; Vitrik, O B; Kuchmizhak, A A; Emel'yanov, V I; Ionin, A A; Kudryashov, S I; Makarov, S V

    2014-08-01

    A type of laser-induced surface relief nanostructure-the nanocrown-on thin metallic films was studied both experimentally and theoretically. The nanocrowns, representing a thin corrugated rim of resolidified melt and resembling well-known impact-induced water-crown splashes, were produced by single diffraction-limited nanosecond laser pulses on thin gold films of variable thickness on low-melting copper and high-melting tungsten substrates, providing different transient melting and adhesion conditions for these films. The proposed model of the nanocrown formation, based on a hydrodynamical (thermocapillary Marangoni) surface instability and described by a Kuramoto-Sivashinsky equation, envisions key steps of the nanocrown appearance and gives qualitative predictions of the acquired nanocrown parameters. PMID:25215830

  4. Large deflection angle, high-power adaptive fiber optics collimator with preserved near-diffraction-limited beam quality.

    PubMed

    Zhi, Dong; Ma, Yanxing; Chen, Zilun; Wang, Xiaolin; Zhou, Pu; Si, Lei

    2016-05-15

    We report on the development of a monolithic adaptive fiber optics collimator, with a large deflection angle and preserved near-diffraction-limited beam quality, that has been tested at a maximal output power at the 300 W level. Additionally, a new measurement method of beam quality (M2 factor) is developed. Experimental results show that the deflection angle of the collimated beam is in the range of 0-0.27 mrad in the X direction and 0-0.19 mrad in the Y direction. The effective working frequency of the device is about 710 Hz. By employing the new measurement method of the M2 factor, we calculate that the beam quality is Mx2=1.35 and My2=1.24, which is in agreement with the result from the beam propagation analyzer and is preserved well with the increasing output power. PMID:27176966

  5. Advances in genetics and genomics: use and limitations in achieving malaria elimination goals

    PubMed Central

    Gunawardena, Sharmini; Karunaweera, Nadira D.

    2015-01-01

    Success of the global research agenda towards eradication of malaria will depend on the development of new tools, including drugs, vaccines, insecticides and diagnostics. Genetic and genomic information now available for the malaria parasites, their mosquito vectors and human host, can be harnessed to both develop these tools and monitor their effectiveness. Here we review and provide specific examples of current technological advances and how these genetic and genomic tools have increased our knowledge of host, parasite and vector biology in relation to malaria elimination and in turn enhanced the potential to reach that goal. We then discuss limitations of these tools and future prospects for the successful achievement of global malaria elimination goals. PMID:25943157

  6. Detection limits of organic compounds achievable with intense, short-pulse lasers.

    PubMed

    Miles, Jordan; De Camillis, Simone; Alexander, Grace; Hamilton, Kathryn; Kelly, Thomas J; Costello, John T; Zepf, Matthew; Williams, Ian D; Greenwood, Jason B

    2015-06-21

    Many organic molecules have strong absorption bands which can be accessed by ultraviolet short pulse lasers to produce efficient ionization. This resonant multiphoton ionization scheme has already been exploited as an ionization source in time-of-flight mass spectrometers used for environmental trace analysis. In the present work we quantify the ultimate potential of this technique by measuring absolute ion yields produced from the interaction of 267 nm femtosecond laser pulses with the organic molecules indole and toluene, and gases Xe, N2 and O2. Using multiphoton ionization cross sections extracted from these results, we show that the laser pulse parameters required for real-time detection of aromatic molecules at concentrations of one part per trillion in air and a limit of detection of a few attomoles are achievable with presently available commercial laser systems. The potential applications for the analysis of human breath, blood and tissue samples are discussed. PMID:25929227

  7. Microstructure analysis of complex CuO/ZnO@carbon adsorbers: what are the limits of powder diffraction methods?

    PubMed

    Tseng, J C; Schmidt, W; Sager, U; Däuber, E; Pommerin, A; Weidenthaler, C

    2015-05-14

    Activate carbon impregnated with a mixture of copper oxide and zinc oxide performs well as active adsorber for NO2 removal in automotive cabin air filters. The oxide-loaded activated carbon exhibits superior long-term stability in comparison to pure activated carbon as has been shown in previous studies. The carbon material was loaded only with 2.5 wt% of each metal oxide. Characterization of the oxide nanoparticles within the pores of the activated carbon is difficult because of the rather low concentration of the oxides. Therefore, a systematic study was performed to evaluate the limits of line profile analysis of X-ray powder diffraction patterns. The method allows evaluation of crystalline domain size distributions, crystal defect concentrations and twinning probabilities of nanoscopic materials. Here, the analysis is hampered by the presence of several phases including more or less amorphous carbon. By using physical mixtures of defined copper oxide and zinc oxide particles with activated carbon, potential errors and limits could be identified. The contribution of the activated carbon to the scattering curve was modeled with a convolution of an exponential decay curve, a Chebyshev polynomial, and two Lorentzian peaks. With this approach, domain size distributions can be calculated that are shifted only by about 0.5-1.0 nm for very low loadings (≤4 wt%). Oxide loadings of 4 wt% and 5 wt% allow very reliable analyses from diffraction patterns measured in Bragg-Brentano and Debye-Scherrer geometry, respectively. For the real adsorber material, mean domain sizes have been calculated to be 2.8 nm and 2.4 nm before and after the NO2 removal tests. PMID:25892653

  8. The Surprising Outburst Behavior of Z Canis Majoris, and Resolving the Alpha Oph Companion Near the Diffraction limit

    NASA Astrophysics Data System (ADS)

    Hinkley, Sasha; Pope, Benjamin; Martinache, Frantz; Hillenbrand, Lynne; Kraus, Adam L.; Ireland, Michael; Oppenheimer, Ben R.; Rice, Emily L.; Monnier, John D.; Tuthill, Peter; Latyshev, Alexey

    2015-01-01

    We present recent high resolution Palomar and Keck observations on two intriguing binary star systems: Z Canis Majoris and Alpha Ophiuchus. We have obtained near-infrared Keck and Palomar photometry and spectra for each component of the Z Canis Majoris system, a very young binary composed of an FU Ori object and a Herbig Ae/Be object. Our high angular resolution photometry of this very young (~1 Myr) binary conclusively determines that the outburst was due solely to the embedded Herbig Ae/Be member, supporting results from earlier works. Further, our high-resolution K-band spectra during a quiescent phase definitively demonstrate that the 2.294 micron CO absorption feature seen in composite spectra of the system is due solely to the FU Ori component, while a prominent CO emission feature at the same wavelength, long suspected to be associated with the innermost regions of a circumstellar accretion disk, can be assigned to the Herbig Ae/Be member. These findings greatly clarify previous analyses of the origin of the CO emission in this complex system. In a different study, we detected the faint companion to the star Alpha Ophiuchus using the Palomar 5m Hale Telescope Adaptive Optics system combined with kernel phase interferometry, a recently-developed post-processing technique for high contrast imaging. The technique of kernel phase interferometry has never before been used to detect faint companions to nearby stars using ground-based observations. Our Palomar observations detect the Alpha Oph companion passing near its periastron point with separation of only ~130 miliarcseconds, close to the Palomar infrared diffraction limit. Alpha Oph is a particularly important binary system with the primary star rotating close to its breakup velocity. Thus, establishing the host star mass with high precision through dynamical orbital analysis is extremely valuable. This technique holds great promise for detecting high contrast objects at, or just inside, the formal

  9. Piloted Simulator Investigation of Techniques to Achieve Attitude Command Response with Limited Authority Servos

    NASA Technical Reports Server (NTRS)

    Key, David L.; Heffley, Robert K.

    2002-01-01

    The purpose of the study was to develop generic design principles for obtaining attitude command response in moderate to aggressive maneuvers without increasing SCAS series servo authority from the existing +/- 10%. In particular, to develop a scheme that would work on the UH-60 helicopter so that it can be considered for incorporation in future upgrades. The basic math model was a UH-60A version of GENHEL. The simulation facility was the NASA-Ames Vertical Motion Simulator (VMS). Evaluation tasks were Hover, Acceleration-Deceleration, and Sidestep, as defined in ADS-33D-PRF for Degraded Visual Environment (DVE). The DVE was adjusted to provide a Usable Cue Environment (UCE) equal to two. The basic concept investigated was the extent to which the limited attitude command authority achievable by the series servo could be supplemented by a 10%/sec trim servo. The architecture used provided angular rate feedback to only the series servo, shared the attitude feedback between the series and trim servos, and when the series servo approached saturation the attitude feedback was slowly phased out. Results show that modest use of the trim servo does improve pilot ratings, especially in and around hover. This improvement can be achieved with little degradation in response predictability during moderately aggressive maneuvers.

  10. Magnetic properties with multiwavelets and DFT: the complete basis set limit achieved.

    PubMed

    Jensen, Stig Rune; Flå, Tor; Jonsson, Dan; Monstad, Rune Sørland; Ruud, Kenneth; Frediani, Luca

    2016-08-01

    Multiwavelets are emerging as an attractive alternative to traditional basis sets such as Gaussian-type orbitals and plane waves. One of their distinctive properties is the ability to reach the basis set limit (often a chimera for traditional approaches) reliably and consistently by fixing the desired precision ε. We present our multiwavelet implementation of the linear response formalism, applied to static magnetic properties, at the self-consistent field level of theory (both for Hartree-Fock and density functional theories). We demonstrate that the multiwavelets consistently improve the accuracy of the results when increasing the desired precision, yielding results that have four to five digits precision, thus providing a very useful benchmark which could otherwise only be estimated by extrapolation methods. Our results show that magnetizabilities obtained with the augmented quadruple-ζ basis (aug-cc-pCVQZ) are practically at the basis set limit, whereas absolute nuclear magnetic resonance shielding tensors are more challenging: even by making use of a standard extrapolation method, the accuracy is not substantially improved. In contrast, our results provide a benchmark that: (1) confirms the validity of the extrapolation ansatz; (2) can be used as a reference to achieve a property-specific extrapolation scheme, thus providing a means to obtain much better extrapolated results; (3) allows us to separate functional-specific errors from basis-set ones and thus to assess the level of cancellation between basis set and functional errors often exploited in density functional theory. PMID:27087397

  11. Simple Limits on Achieving A Quasi-Linear Magnetic Compression for an FEL Driver

    SciTech Connect

    Sun, Yipeng; /SLAC

    2012-02-16

    Free electron lasers (FEL) need a very bright electron beam in three dimensions and a high peak charge density. In order to compress an initially longer electron bunch generated from the photoinjector, magnetic bunch compression systems are widely employed. In this paper, first harmonic RF linearization and its associated requirements are reviewed. Meanwhile it is also briefly discussed what is the relation between a proper initial bunch length and main RF frequency, when a harmonic RF linearization is included. Then given a reasonable bunch compression ratio, a proper initial bunch length as a function of the main RF frequency and RF phase is estimated analytically by several approaches, assuming that no harmonic RF section is needed to linearize the energy modulation introduced during main RF acceleration, and at the same time still linearly compress the bunch length. Next the upper limit of the bunch compression ratio in a single stage is evaluated analytically. The analytical relations derived on choosing a proper initial bunch length as a function of main RF frequency are confirmed by numerical simulation. These simple limit provide rough estimations and may be beneficial for choosing bunch compression ratios in different stages of an FEL driver, especially in a first stage bunch compression where there is usually a harmonic RF linearization applied. It may also be useful in evaluating the possibility of low charge operation mode without any harmonic RF linearization, where a shorter initial bunch length can be achieved from the photoinjector.

  12. Achieving Thermodynamic Limit of Subthreshold Slope in Nanoscale Schottky Barrier MOSFET with Pillar Structure Inserted

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Yong; Jung, Sungchul; Park, Kibog

    As the device size decreases continuously by scaling in the current Si CMOS technology, subthreshold slope which is related to device operation and leakage current becomes more and more important. Especially, the drain induced barrier lowering (DIBL) modulation for improving subthreshold slope in metal/oxide/metal field effect transistor (MOSFET) is difficult to achieve. We propose a new device structure, edge-over Schottky Barrier MOSFET (EO-SB-MOSFET), which shows low DIBL and subthreshold slope approaching the thermodynamic limit of 60 mV/DEC at room temperature. EO-SB-MOSFET has a pillar structure which elongates the transistor channel by forming it over the edge of pillar. Hence, EO-SB-MOSFET has a much longer channel compared with planar MOSFET in the same pitch. We performed 2-dimensional TCAD modeling on an EO-SB-MOSFET with channel lateral size of 6.5 nm and pillar height of 36 nm. The TCAD modeling predicts DIBL of ~5 mV/V, subthreshold slope of ~61.3 mV/DEC, and off-state current of ~0.1 nA/ μm at drain bias 0.5 V. It is also noticed that the subthreshold slope gets further close to the thermodynamic limit as the pillar height increases. Supported by NRF in South Korea (2013R1A1A2007070).

  13. A collimated focused ultrasound beam of high acoustic transmission and minimum diffraction achieved by using a lens with subwavelength structures

    SciTech Connect

    Lin, Zhou; Tu, Juan; Cheng, Jianchun; Guo, Xiasheng E-mail: dzhang@nju.edu.cn; Wu, Junru; Huang, Pingtong; Zhang, Dong E-mail: dzhang@nju.edu.cn

    2015-09-14

    An acoustic focusing lens incorporated with periodically aligned subwavelength grooves corrugated on its spherical surface has been developed. It is demonstrated theoretically and experimentally that acoustic focusing achieved by using the lens can suppress the relative side-lobe amplitudes, enhance the focal gain, and minimize the shifting of the focus. Use of the lens coupled with a planar ultrasound transducer can generate an ultrasound beam with enhanced acoustic transmission and collimation effect, which offers the capability of improving the safety, efficiency, and accuracy of targeted surgery implemented by high intensity focused ultrasound.

  14. Phase noise in pulsed Doppler lidar and limitations on achievable single-shot velocity accuracy

    NASA Technical Reports Server (NTRS)

    Mcnicholl, P.; Alejandro, S.

    1992-01-01

    The smaller sampling volumes afforded by Doppler lidars compared to radars allows for spatial resolutions at and below some sheer and turbulence wind structure scale sizes. This has brought new emphasis on achieving the optimum product of wind velocity and range resolutions. Several recent studies have considered the effects of amplitude noise, reduction algorithms, and possible hardware related signal artifacts on obtainable velocity accuracy. We discuss here the limitation on this accuracy resulting from the incoherent nature and finite temporal extent of backscatter from aerosols. For a lidar return from a hard (or slab) target, the phase of the intermediate frequency (IF) signal is random and the total return energy fluctuates from shot to shot due to speckle; however, the offset from the transmitted frequency is determinable with an accuracy subject only to instrumental effects and the signal to noise ratio (SNR), the noise being determined by the LO power in the shot noise limited regime. This is not the case for a return from a media extending over a range on the order of or greater than the spatial extent of the transmitted pulse, such as from atmospheric aerosols. In this case, the phase of the IF signal will exhibit a temporal random walk like behavior. It will be uncorrelated over times greater than the pulse duration as the transmitted pulse samples non-overlapping volumes of scattering centers. Frequency analysis of the IF signal in a window similar to the transmitted pulse envelope will therefore show shot-to-shot frequency deviations on the order of the inverse pulse duration reflecting the random phase rate variations. Like speckle, these deviations arise from the incoherent nature of the scattering process and diminish if the IF signal is averaged over times greater than a single range resolution cell (here the pulse duration). Apart from limiting the high SNR performance of a Doppler lidar, this shot-to-shot variance in velocity estimates has a

  15. Sensitivity and noise in GC-MS: Achieving low limits of detection for difficult analytes

    NASA Astrophysics Data System (ADS)

    Fialkov, Alexander B.; Steiner, Urs; Lehotay, Steven J.; Amirav, Aviv

    2007-01-01

    Gas chromatography-mass spectrometry (GC-MS) instrument limit of detection (LOD) is typically listed by major vendors as that of octafluoronaphthalene (OFN). Most current GC-MS instruments can achieve LODs in the low femtogram range. However, GC-MS LODs for realistic analytes in actual samples are often a few orders of magnitude higher than OFN's. Users seldom encounter 1 pg LOD in the single ion monitoring mode in their applications. We define this detectability difference as the "OFN gap." In this paper, we demonstrate and discuss how the OFN gap can be significantly reduced by the use of GC-MS with supersonic molecular beams (SMB). Experimental results were obtained with a recently developed GC-MS with SMB named 1200-SMB, that is based on the conversion of the Varian 1200 system into a GC-MS-MS with SMB. With this 1200-SMB system, the LOD of all types of analytes, including OFN, in real samples is significantly improved through the combination of: (a) enhanced molecular ion; (b) elimination of vacuum background noise; (c) elimination of mass independent noise; (d) elimination of ion source peak tailing and degradation; (e) significantly increased range of thermally labile and low volatility compounds that are amenable for analysis through lower sample elution temperatures; (f) reduced column bleed and ghost peaks through sample elution at lower temperatures; (g) improved compatibility with large volume injections; and (h) reduced matrix interferences through the combination of enhanced molecular ion and MS-MS. As a result, the 1200-SMB LODs of common and/or difficult compounds are much closer to its OFN LOD, even in complex matrices. We crossed the <1 fg OFN LOD milestone to achieve the lowest LOD to date using GC-MS, but more importantly, we attained LOD of 2 fg for diazinon, a common pesticide analyte. In another example, we achieved an LOD of 10 fg for underivatized testosterone, which is not amenable in traditional GC-MS analysis, and conducted many analyses

  16. Generation of 3.5 W of diffraction-limited green light from SHG of a single tapered diode laser in a cascade of nonlinear crystals

    NASA Astrophysics Data System (ADS)

    Hansen, Anders K.; Jensen, Ole B.; Sumpf, Bernd; Erbert, Götz; Unterhuber, Angelika; Drexler, Wolfgang; Andersen, Peter E.; Petersen, Paul Michael

    2014-02-01

    Many applications, e.g., within biomedicine stand to benefit greatly from the development of diode laser-based multi- Watt efficient compact green laser sources. The low power of existing diode lasers in the green area (about 100 mW) means that the most promising approach remains nonlinear frequency conversion of infrared tapered diode lasers. Here, we describe the generation of 3.5 W of diffraction-limited green light from SHG of a single tapered diode laser, itself yielding 10 W at 1063 nm. This SHG is performed in single pass through a cascade of two PPMgO:LN crystals with re-focusing and dispersion compensating optics between the two nonlinear crystals. In the low-power limit, such a cascade of two crystals has the theoretical potential for generation of four times as much power as a single crystal without adding significantly to the complexity of the system. The experimentally achieved power of 3.5 W corresponds to a power enhancement greater than 2 compared to SHG in each of the crystals individually and is the highest visible output power generated by frequency conversion of a single diode laser. Such laser sources provide the necessary pump power for biophotonics applications, such as optical coherence tomography or multimodal imaging devices, e.g., FTCARS-OCT, based on a strongly pumped ultrafast Ti:Sapphire laser.

  17. Achieving large ends with limited means: grand strategy in global health.

    PubMed

    Curry, Leslie A; Luong, Minh A; Krumholz, Harlan M; Gaddis, John; Kennedy, Paul; Rulisa, Stephen; Taylor, Lauren; Bradley, Elizabeth H

    2010-06-01

    Unprecedented attention is focused on global health, with a four-fold increase in development assistance in the last 15 years and the scope of global health expanding beyond infectious disease to include chronic disease and health systems strengthening. As the global impact of health is more widely understood, it has become a crucial element of international relations, economic development, and foreign affairs. At this potential leverage point in the global health movement, the application of grand strategy is of critical importance. Grand strategy, i.e., the development and implementation of comprehensive plans of action to achieve large ends with limited means, has been refined through centuries of international relations and the management of states but has been inadequately applied to global health policy and implementation. We review key principles of grand strategy and demonstrate their applicability to a central global health issue: maternal mortality. The principles include: start with the end in mind, take an ecological approach, recognize that tactics matter, use positive deviance to characterize practical solutions and foster scale-up, and integrate timely intelligence and data into health interventions and improvement efforts. We advocate for the greater use of grand strategy in global health. PMID:24037468

  18. The molecular-kinetic approach to wetting dynamics: Achievements and limitations.

    PubMed

    Sedev, Rossen

    2015-08-01

    The molecular-kinetic theory (MKT) of dynamic wetting was formulated almost 50 years ago. It explains the dependence of the dynamic contact angle on the speed of a moving meniscus by estimating the non-hydrodynamic dissipation in the contact line. Over the years it has been refined to account explicitly for the influence of (bulk) fluid viscosity and it has been applied successfully to both solid-liquid-vapour and solid-liquid-liquid systems. The free energy barrier for surface diffusion has been related to the energy of adhesion. The MKT provides a qualitative explanation for most effects in dynamic wetting. The theory is simple, flexible, and it is widely used to rationalize the physics of wetting dynamics and fit experimental data (dynamic contact angle versus contact line speed). The MKT predicts an intermediate wettability as optimal for high-speed coating as well as the maximum speeds of wetting and dewetting. Nevertheless, the values of the molecular parameters derived from experimental data tend to be scattered and not particularly reliable. This review outlines the main achievements and limitations of the MKT and highlights some common cases of misinterpretation. PMID:25449187

  19. Occult peripheral artery disease is common and limits the benefit achieved in cardiac rehabilitation.

    PubMed

    Tam, Marty C; Longenecker, Chris T; Chow, Chen; Vest, Marianne; Sukeena, Richard; Madan Mohan, Sri K; Carman, Teresa; Parikh, Sahil A; Josephson, Richard A

    2016-04-01

    Cardiac rehabilitation (CR) has proven morbidity and mortality benefits in cardiovascular disease, which directly correlates with exercise performance achieved. Many patients in CR exercise at sub-optimal levels, without obvious limitations. Occult lower-extremity peripheral artery disease (PAD) may be a determinant of diminished exercise capacity and reduced benefit obtained from traditional CR. In this prospective study of 150 consecutive patients enrolled in Phase II CR, we describe the prevalence of PAD, the utility of externally validated screening questionnaires, and the observed impact on CR outcomes. Abnormal ankle-brachial indices (ABI) (< 0.9 and >1.4) were observed in 19% of those studied. The Edinburgh Claudication Questionnaire was insensitive for detecting PAD by low ABI in this population, and the Walking Impairment Questionnaire and a modified Gardner protocol demonstrated a lack of typical symptoms with low levels of activity. Importantly, at completion of traditional CR, exercise improvement measured in metabolic equivalents (METs) was worse in those with a low ABI compared to those with a normal ABI (+1.39 vs +2.41 METs, p = 0.002). In conclusion, PAD is common in patients in Phase II CR and often clinically occult. Screening based on standard questionnaires appears insensitive in this population, suggesting a need for a broad-based screening strategy with ABI measurements. In this study, undiagnosed PAD significantly attenuated improvements in exercise performance, which potentially has bearings on future clinical events. PMID:26850114

  20. Observation of coupled plasmon-polariton modes of plasmon waveguides for electromagnetic energy transport below the diffraction limit

    NASA Astrophysics Data System (ADS)

    Maier, Stefan A.; Kik, Pieter G.; Atwater, Harry A.; Meltzer, Sheffer; Requicha, Aristides A. G.; Koel, Bruce E.

    2002-10-01

    We investigate the possibility of using arrays of closely spaced metal nanoparticles as plasmon waveguides for electromagnetic energy below the diffraction limit of light. Far-field spectroscopy on arrays of closely spaced 50 nm Au particles fabricated using electron beam lithography reveals the presence of near-field optical particle interactions that lead to shifts in the plasmon resonance frequencies for longitudinal and transverse excitations. We link this observation to a point-dipole model for energy transfer in plasmon waveguides and give an estimate of the expected group velocities and energy decay lengths for the fabricated structures. A near-field optical excitation and detection scheme for energy transport is proposed and demonstrated. The fabricated structures show a high propagation loss of about 3 dB / 15 nm which renders a direct experimental observation of energy transfer impossible. The nature of the loss and ways to decrease it by an order of magnitude are discussed. We also present finite-difference time-domain simulations on the energy transfer properties of plasmon waveguides.

  1. 2 kW narrow spectral width monolithic continuous wave in a near-diffraction-limited fiber laser.

    PubMed

    Xu, Yang; Fang, Qiang; Qin, Yuguo; Meng, Xiangjie; Shi, Wei

    2015-11-10

    We demonstrate a monolithic continuous wave (CW) fiber laser source at 1070 nm, producing 2 kW laser power with a very narrow spectral width (∼75  GHz) and near-diffraction-limited beam quality (M2<1.4). The laser consists of a CW fiber laser oscillator and two double cladding fiber amplifiers in the master oscillator-power amplifier configuration. The master oscillator is a distributed Bragg reflected fiber laser, producing ∼6  W laser power with ∼25  GHz spectral width. The two double cladding fiber amplifiers were developed to enhance the laser power up to ∼200 and ∼2050  W, respectively. The slope efficiency of the main amplifier reaches 84.8%. Under the full power output, the 3 dB spectral width and 20 dB spectral width of the laser emission spectrum was ∼75  GHz and 1.2 nm, respectively. PMID:26560767

  2. Localized tip enhanced Raman spectroscopic study of impurity incorporated single GaN nanowire in the sub-diffraction limit

    SciTech Connect

    Patsha, Avinash E-mail: dhara@igcar.gov.in; Dhara, Sandip; Tyagi, A. K.

    2015-09-21

    The localized effect of impurities in single GaN nanowires in the sub-diffraction limit is reported using the study of lattice vibrational modes in the evanescent field of Au nanoparticle assisted tip enhanced Raman spectroscopy (TERS). GaN nanowires with the O impurity and the Mg dopants were grown by the chemical vapor deposition technique in the catalyst assisted vapor-liquid-solid process. Symmetry allowed Raman modes of wurtzite GaN are observed for undoped and doped nanowires. Unusually very strong intensity of the non-zone center zone boundary mode is observed for the TERS studies of both the undoped and the Mg doped GaN single nanowires. Surface optical mode of A{sub 1} symmetry is also observed for both the undoped and the Mg doped GaN samples. A strong coupling of longitudinal optical (LO) phonons with free electrons, however, is reported only in the O rich single nanowires with the asymmetric A{sub 1}(LO) mode. Study of the local vibration mode shows the presence of Mg as dopant in the single GaN nanowires.

  3. Enhancement of low-quality reconstructed digital hologram images based on frequency extrapolation of large objects under the diffraction limit

    NASA Astrophysics Data System (ADS)

    Liu, Ning; Li, Weiliang; Zhao, Dongxue

    2016-03-01

    During the reconstruction of a digital hologram, the reconstructed image is usually degraded by speckle noise, which makes it hard to observe the original object pattern. In this paper, a new reconstructed image enhancement method is proposed, which first reduces the speckle noise using an adaptive Gaussian filter, then calculates the high frequencies that belong to the object pattern based on a frequency extrapolation strategy. The proposed frequency extrapolation first calculates the frequency spectrum of the Fourier-filtered image, which is originally reconstructed from the +1 order of the hologram, and then gives the initial parameters for an iterative solution. The analytic iteration is implemented by continuous gradient threshold convergence to estimate the image level and vertical gradient information. The predicted spectrum is acquired through the analytical iteration of the original spectrum and gradient spectrum analysis. Finally, the reconstructed spectrum of the restoration image is acquired from the synthetic correction of the original spectrum using the predicted gradient spectrum. We conducted our experiment very close to the diffraction limit and used low-quality equipment to prove the feasibility of our method. Detailed analysis and figure demonstrations are presented in the paper.

  4. Enhancement of low-quality reconstructed digital hologram images based on frequency extrapolation of large objects under the diffraction limit

    NASA Astrophysics Data System (ADS)

    Liu, Ning; Li, Weiliang; Zhao, Dongxue

    2016-06-01

    During the reconstruction of a digital hologram, the reconstructed image is usually degraded by speckle noise, which makes it hard to observe the original object pattern. In this paper, a new reconstructed image enhancement method is proposed, which first reduces the speckle noise using an adaptive Gaussian filter, then calculates the high frequencies that belong to the object pattern based on a frequency extrapolation strategy. The proposed frequency extrapolation first calculates the frequency spectrum of the Fourier-filtered image, which is originally reconstructed from the +1 order of the hologram, and then gives the initial parameters for an iterative solution. The analytic iteration is implemented by continuous gradient threshold convergence to estimate the image level and vertical gradient information. The predicted spectrum is acquired through the analytical iteration of the original spectrum and gradient spectrum analysis. Finally, the reconstructed spectrum of the restoration image is acquired from the synthetic correction of the original spectrum using the predicted gradient spectrum. We conducted our experiment very close to the diffraction limit and used low-quality equipment to prove the feasibility of our method. Detailed analysis and figure demonstrations are presented in the paper.

  5. Investigation of Stimulated Raman Scattering Using Short-Pulse Diffraction Limited Laser Beam near the Instability Threshold

    NASA Astrophysics Data System (ADS)

    Kline, J. L.; Montgomery, D. S.; Yin, L.; Flippo, K. A.; Albright, B. J.; Johnson, R. P.; Shimada, T.; Rose, H. A.; Rousseaux, C.; Tassin, V.; Baton, S. D.; Amiranoff, F.; Hardin, R. A.

    2008-11-01

    Short pulse laser plasma interaction experiments using diffraction limited beams provide an excellent platform to investigate the fundamental physics of Stimulated Raman (SRS) and Stimulated Brillouin (SBS) Scattering. Detailed understanding of these laser plasma instabilities impacts the current inertial confinement fusion ignition designs and could potentially impact fast ignition when higher energy lasers are used with longer pulse durations ( > 1 kJ and > 1 ps). Using short laser pulses, experiments can be modeled over the entire interaction time of the laser using PIC codes to validate our understanding. Experiments have been conducted at the Trident laser and the LULI to investigate SRS near the threshold of the instability using 527 and 1064 nm laser light respectively with 1.5 -- 3 ps pulses. In the case of both experiments, the interaction beam was focused into a pre-ionized He gasjet plasma. Measurements of the reflectivity as a function of intensity and k?D were completed at the Trident laser. At LULI, a 300 fs Thomson scattering probe is used to directly measure the density fluctuations of the driven electron plasma and ion acoustic waves. Details of the experimental results will be presented.

  6. 40 CFR 449.10 - Effluent limitations representing the best available technology economically achievable (BAT).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... available technology economically achievable (BAT). Except as provided in 40 CFR 125.30 through 125.32, any... best available technology economically achievable (BAT). 449.10 Section 449.10 Protection of... following requirements representing the degree of effluent reduction attainable by the application of...

  7. 40 CFR 449.10 - Effluent limitations representing the best available technology economically achievable (BAT).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... available technology economically achievable (BAT). Except as provided in 40 CFR 125.30 through 125.32, any... best available technology economically achievable (BAT). 449.10 Section 449.10 Protection of... following requirements representing the degree of effluent reduction attainable by the application of...

  8. 40 CFR 449.10 - Effluent limitations representing the best available technology economically achievable (BAT).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... available technology economically achievable (BAT). Except as provided in 40 CFR 125.30 through 125.32, any... best available technology economically achievable (BAT). 449.10 Section 449.10 Protection of... following requirements representing the degree of effluent reduction attainable by the application of...

  9. Thermal infrared properties of classical and type II Cepheids. Diffraction limited 10 μm imaging with VLT/VISIR

    NASA Astrophysics Data System (ADS)

    Gallenne, A.; Kervella, P.; Mérand, A.

    2012-02-01

    We present new thermal infrared (IR) photometry and spectral energy distributions (SEDs) of eight classical Cepheids (type I) and three type II Cepheids, using VISIR thermal IR photometric measurements, supplemented with literature data. We used the BURST mode of the instrument to get diffraction-limited images at 8.59, 11.25, and 11.85 μm. The SEDs show a IR excess at wavelengths longer than 10 μm in ten of the eleven stars. We tentatively attribute these excesses to circumstellar emission created by mass loss from the Cepheids. On the basis of some hypotheses for the dust composition, we estimate a total mass of the envelope ranging from 10-10 to 10-8 M⊙. We also detect a spatially extended emission around AX Cir, X Sgr, W Sgr, Y Oph, and U Car, while we do not resolve the circumstellar envelope (CSE) of the other stars. The averaged circumstellar envelope brightnesses relative to the stellar photosphere are α(AX Cir) = 13.8 ± 2.5%,α(X Sgr) = 7.9 ± 1.4%,α(W Sgr) = 3.8 ± 0.6%,α(Y Oph) = 15.1 ± 1.4%, and α(U Car) = 16.3 ± 1.4% at 8.59 μm. With this study, we extend the number of classical Cepheids with detected CSEs from 9 to 14, confirming that at least a large fraction of all Cepheids are experiencing significant mass loss. The presence of these CSEs may also impact the future use of Cepheids as standard candles at near and thermal infrared wavelengths. Based on observations made with ESO telescopes at Paranal observatory under program ID 081.D-0165(A).Table 2 is only available in electronic form at http://www.aanda.org

  10. An assessment of the resolution limitation due to radiation-damage in X-ray diffraction microscopy

    DOE PAGESBeta

    Howells, M. R.; Beetz, T.; Chapman, H. N.; Cui, C.; Holton, J. M.; Jacobsen, C. J.; Kirz, J.; Lima, E.; Marchesini, S.; Miao, H.; et al

    2008-11-17

    X-ray diffraction microscopy (XDM) is a new form of x-ray imaging that is being practiced at several third-generation synchrotron-radiation x-ray facilities. Nine years have elapsed since the technique was first introduced and it has made rapid progress in demonstrating high-resolution three-dimensional imaging and promises few-nm resolution with much larger samples than can be imaged in the transmission electron microscope. Both life- and materials-science applications of XDM are intended, and it is expected that the principal limitation to resolution will be radiation damage for life science and the coherent power of available x-ray sources for material science. In this paper wemore » address the question of the role of radiation damage. We use a statistical analysis based on the so-called "dose fractionation theorem" of Hegerl and Hoppe to calculate the dose needed to make an image of a single life-science sample by XDM with a given resolution. We find that for simply-shaped objects the needed dose scales with the inverse fourth power of the resolution and present experimental evidence to support this finding. To determine the maximum tolerable dose we have assembled a number of data taken from the literature plus some measurements of our own which cover ranges of resolution that are not well covered otherwise. The conclusion of this study is that, based on the natural contrast between protein and water and "Rose-criterion" image quality, one should be able to image a frozen-hydrated biological sample using XDM at a resolution of about 10 nm.« less

  11. An assessment of the resolution limitation due to radiation-damage in X-ray diffraction microscopy

    SciTech Connect

    Howells, M. R.; Beetz, T.; Chapman, H. N.; Cui, C.; Holton, J. M.; Jacobsen, C. J.; Kirz, J.; Lima, E.; Marchesini, S.; Miao, H.; Sayre, D.; Shapiro, D. A.; Spence, J. C.H.; Starodub, D.

    2008-11-17

    X-ray diffraction microscopy (XDM) is a new form of x-ray imaging that is being practiced at several third-generation synchrotron-radiation x-ray facilities. Nine years have elapsed since the technique was first introduced and it has made rapid progress in demonstrating high-resolution three-dimensional imaging and promises few-nm resolution with much larger samples than can be imaged in the transmission electron microscope. Both life- and materials-science applications of XDM are intended, and it is expected that the principal limitation to resolution will be radiation damage for life science and the coherent power of available x-ray sources for material science. In this paper we address the question of the role of radiation damage. We use a statistical analysis based on the so-called "dose fractionation theorem" of Hegerl and Hoppe to calculate the dose needed to make an image of a single life-science sample by XDM with a given resolution. We find that for simply-shaped objects the needed dose scales with the inverse fourth power of the resolution and present experimental evidence to support this finding. To determine the maximum tolerable dose we have assembled a number of data taken from the literature plus some measurements of our own which cover ranges of resolution that are not well covered otherwise. The conclusion of this study is that, based on the natural contrast between protein and water and "Rose-criterion" image quality, one should be able to image a frozen-hydrated biological sample using XDM at a resolution of about 10 nm.

  12. Reaching the Diffraction Limit - Differential Speckle and Wide-Field Imaging for the Gemini-N Telescope

    NASA Technical Reports Server (NTRS)

    Scott, Nic J.; Howell, Steve; Horch, Elliott

    2016-01-01

    Speckle imaging allows telescopes to achieve di raction limited imaging performance. The technique requires cameras capable of reading out frames at a very fast rate, e ectively `freezing out' atmospheric seeing. The resulting speckles can be correlated and images reconstructed that are at the di raction limit of the telescope. These new instruments are based on the successful performance and design of the Di erential Speckle Survey Instrument (DSSI) [2, 1]. The instruments are being built for the Gemini-N and WIYN telescopes and will be made available to the community via the peer review proposal process. We envision their primary use to be validation and characterization of exoplanet targets from the NASA K2 and TESS missions and RV discovered exoplanets. Such targets will provide excellent follow-up candidates for both the WIYN and Gemini telescopes [3]. Examples of DSSI data are shown in the gures below. We expect similar data quality in speckle imaging mode with the new instruments. Additionally, both cameras will have a wide- eld mode and standard SDSS lters. They will be highly versatile instruments and it is that likely many other science programs will request time on the cameras. The limiting magnitude for speckle observations, will remain around 13-14th at WIYN and 16-17th at Gemini, while wide- eld, normal CCD imaging operation should be able to go to much fainter, providing usual CCD imaging and photometric capabilities. The instruments will also have high utility as scoring cameras for telescope engineering purposes, or other applications where high time resolution is needed. Instrument support will be provided, including a software pipeline that takes raw speckle data to fully reconstructed images.

  13. Bandwidth efficient coding: Theoretical limits and real achievements. Error control techniques for satellite and space communications

    NASA Technical Reports Server (NTRS)

    Costello, Daniel J., Jr.; Courturier, Servanne; Levy, Yannick; Mills, Diane G.; Perez, Lance C.; Wang, Fu-Quan

    1993-01-01

    In his seminal 1948 paper 'The Mathematical Theory of Communication,' Claude E. Shannon derived the 'channel coding theorem' which has an explicit upper bound, called the channel capacity, on the rate at which 'information' could be transmitted reliably on a given communication channel. Shannon's result was an existence theorem and did not give specific codes to achieve the bound. Some skeptics have claimed that the dramatic performance improvements predicted by Shannon are not achievable in practice. The advances made in the area of coded modulation in the past decade have made communications engineers optimistic about the possibility of achieving or at least coming close to channel capacity. Here we consider the possibility in the light of current research results.

  14. Energy saving achieved by limited filamentous bulking sludge under low dissolved oxygen.

    PubMed

    Guo, Jian-Hua; Peng, Yong-Zhen; Peng, Cheng-Yao; Wang, Shu-Ying; Chen, Ying; Huang, Hui-Jun; Sun, Zhi-Rong

    2010-02-01

    Limited filamentous bulking caused by low dissolved oxygen (DO) was proposed to establish a low energy consumption wastewater treatment system. This method for energy saving was derived from two full-scale field observations, which showed pollutants removal would be enhanced and energy consumption could be reduced by at least 10% using limited filamentous bulking. Furthermore, preliminary investigation including the abundance evaluation and the identification of filamentous bacteria demonstrated that the limited filamentous bulking could be repeated steadily in a lab-scale anoxic-oxic reactor fed with domestic wastewater. The sludge loss did not occur in the secondary clarifier, while COD and total nitrogen removal efficiencies were improved by controlling DO for optimal filamentous bacterial population. Suspended solids in effluent were negligible and turbidity was lower than 2 NTU, which were distinctly lower than those under no bulking. Theoretical and experimental results indicated the aeration consumption could be saved by the application of limited filamentous bulking. PMID:19837583

  15. Beyond the diffraction limit of optical/IR interferometers. I. Angular diameter and rotation parameters of Achernar from differential phases

    NASA Astrophysics Data System (ADS)

    Domiciano de Souza, A.; Hadjara, M.; Vakili, F.; Bendjoya, P.; Millour, F.; Abe, L.; Carciofi, A. C.; Faes, D. M.; Kervella, P.; Lagarde, S.; Marconi, A.; Monin, J.-L.; Niccolini, G.; Petrov, R. G.; Weigelt, G.

    2012-09-01

    that differential phases allow the measurement of sizes up to ~4 times smaller than the diffraction-limited angular resolution of the interferometer. Based on observations performed at ESO, Chile under AMBER-consortium GTO programme ID 084.D-0456.Full Fig. 5 is available in electronic form at http://www.aanda.orgThe FITS tables of the reduced data are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/545/A130

  16. FIRST, a fibered aperture masking instrument. II. Spectroscopy of the Capella binary system at the diffraction limit

    NASA Astrophysics Data System (ADS)

    Huby, E.; Duchêne, G.; Marchis, F.; Lacour, S.; Perrin, G.; Kotani, T.; Choquet, É.; Gates, E. L.; Lai, O.; Allard, F.

    2013-12-01

    Aims: FIRST is a prototype instrument built to demonstrate the capabilities of the pupil remapping technique, using single-mode fibers and working at visible wavelengths. Our immediate objective is to demonstrate the high angular resolution capability of the instrument and to show that the spectral resolution of the instrument enables characterization of stellar companions. Methods: The FIRST-18 instrument is an improved version of FIRST-9 that simultaneously recombines two sets of nine fibers instead of one, thus greatly enhancing the (u, v) plane coverage. We report on observations of the binary system Capella at three epochs over a period of 14 months (≳4 orbital periods) with FIRST-18 mounted on the 3 m Shane telescope at Lick Observatory. The binary separation during our observations ranges from 0.8 to 1.2 times the diffraction limit of the telescope at the central wavelength of the spectral band. Results: We successfully resolved the Capella binary system at all epochs, with an astrometric precision as good as 1 mas under the best observing conditions. FIRST also gives access to the spectral flux ratio between the two components directly measured with an unprecedented spectral resolution of R ~ 300 over the 600-850 nm range. In particular, our data allow detection of the well-known overall slope of the flux ratio spectrum, leading to an estimation of the "pivot" wavelength of 0.64 ± 0.01 μm, at which the cooler component becomes the brightest. Spectral features arising from the difference in effective temperature of the two components (specifically the Hα line, TiO, and CN bands) have been used to constrain the stellar parameters. The effective temperatures we derive for both components are slightly lower (5-7%) than the well-established properties for this system. This difference mainly comes from deeper molecular features than those predicted by state-of-the-art stellar atmospheric models, suggesting that molecular line lists used in the photospheric

  17. [The historical achievement and the limits of the work of Sigmund Freud (1855-1939)].

    PubMed

    Katzenstein, A; Thom, A

    1982-02-01

    In this paper written on the occasion of Sigmund Freud's 125th birthday, an attempt is made to strike a balance of earlier marxist assessments of Freud's work. After a short presentation of the more important biographical and work-historical data, mainly Freud's antropological basic conceptions and their problematic consequences for his personality-theory are dealt with. Freud's historically important achievement is seen in the opening of a psychological access to the understanding of neuroses as well as the discovery of dynamic processes in the psychotherapeutic encounter. PMID:7045908

  18. Beyond the diffraction limit of optical/IR interferometers. II. Stellar parameters of rotating stars from differential phases

    NASA Astrophysics Data System (ADS)

    Hadjara, M.; Domiciano de Souza, A.; Vakili, F.; Jankov, S.; Millour, F.; Meilland, A.; Khorrami, Z.; Chelli, A.; Baffa, C.; Hofmann, K.-H.; Lagarde, S.; Robbe-Dubois, S.

    2014-09-01

    , PArot = 65.6° ± 5°, for Fomalhaut. They were found to be compatible with previously published values from differential phase and visibility measurements, while we were able to determine, for the first time, the inclination angle i of Fomalhaut (i = 90° ± 9°) and δ Aquilae (i = 81° ± 13°), and the rotation-axis position angle PArot of δ Aquilae. Conclusions: Beyond the theoretical diffraction limit of an interferometer (ratio of the wavelength to the baseline), spatial super resolution is well suited to systematically estimating the angular diameters of rotating stars and their fundamental parameters with a few sets of baselines and the Earth-rotation synthesis provided a high enough spectral resolution. Based on observations performed at the European Southern Observatory, Chile, under ESO AMBER-consortium GTO program IDs 084.D-0456 081.D-0293 and 082.C-0376.Figure 5 is available in electronic form at http://www.aanda.org

  19. Classifying and assembling two-dimensional X-ray laser diffraction patterns of a single particle to reconstruct the three-dimensional diffraction intensity function: resolution limit due to the quantum noise

    PubMed Central

    Tokuhisa, Atsushi; Taka, Junichiro; Kono, Hidetoshi; Go, Nobuhiro

    2012-01-01

    A new two-step algorithm is developed for reconstructing the three-dimensional diffraction intensity of a globular biological macromolecule from many experimentally measured quantum-noise-limited two-dimensional X-ray laser diffraction patterns, each for an unknown orientation. The first step is classification of the two-dimensional patterns into groups according to the similarity of direction of the incident X-rays with respect to the molecule and an averaging within each group to reduce the noise. The second step is detection of common intersecting circles between the signal-enhanced two-dimensional patterns to identify their mutual location in the three-dimensional wavenumber space. The newly developed algorithm enables one to detect a signal for classification in noisy experimental photon-count data with as low as ∼0.1 photons per effective pixel. The wavenumber of such a limiting pixel determines the attainable structural resolution. From this fact, the resolution limit due to the quantum noise attainable by this new method of analysis as well as two important experimental parameters, the number of two-dimensional patterns to be measured (the load for the detector) and the number of pairs of two-dimensional patterns to be analysed (the load for the computer), are derived as a function of the incident X-ray intensity and quantities characterizing the target molecule. PMID:22514069

  20. Production of Biodiesel at Kinetic Limit Achieved in a Centrifugal Reactor/Separator

    SciTech Connect

    McFarlane, Joanna; Tsouris, Costas; Birdwell Jr, Joseph F; Lee, Denise L; Jennings, Hal L; Pahmer Boitrago, Amy M; Terpstra, Sarah M

    2010-01-01

    The kinetics of the transesterification of soybean oil has been investigated in a centrifugal reactor at temperatures from 45 to 80 C and pressures up to 2.6 bar using gas chromatography flame ionization detection (GC-FID) and infrared (IR) spectroscopy. The yields of product methyl esters were quantified using IR, proton Nuclear Magnetic Resonance (H1NMR), and viscosity measurements and were found to achieve 90% of the yield in 2 min; however, to meet ASTM specifications with one pass through the reactor, a 15 min residence time was needed. Performance was improved by sequential reactions, allowing separation of by-product glycerine and injection of additional small aliquots of methanol. The kinetics was modeled using a three-step mechanism of reversible reactions, which was used to predict performance at commercial scale. The mechanism correctly predicted the exponential decline in reaction rate as the concentration of the products allowed significant reverse reactions to occur.

  1. DBR tapered diode laser with 12.7 W output power and nearly diffraction-limited, narrowband emission at 1030 nm

    NASA Astrophysics Data System (ADS)

    Müller, André; Fricke, Jörg; Bugge, Frank; Brox, Olaf; Erbert, Götz; Sumpf, Bernd

    2016-04-01

    A 1030 nm distributed Bragg reflector (DBR) tapered diode laser with nearly diffraction-limited emission is presented. The laser provides an optical output power of 12.7 W with an electro-optical efficiency >40 %. At 10.5 W of optical output power, a central lobe power content of 8.1 W and a nearly diffraction-limited beam propagation ratio of M 2 = 1.1 (1/ e 2) are obtained. The corresponding brightness is 700 MW cm-2 sr-1. Compared to previous approaches, intrinsic wavelength stabilization is obtained by a third-order DBR grating manufactured using more reproducible electron-beam lithography. A narrowband emission is measured over the whole power range with a spectral bandwidth of about 17 pm at 12.5 W. Based on the measured electro-optical, spectral and spatial properties, the laser is suitable for applications requiring narrowband, high-power emission with high spatial quality.

  2. Microfluidic means of achieving attomolar detection limits with molecular beacon probes.

    PubMed

    Puleo, Christopher M; Wang, Tza-Huei

    2009-04-21

    We used inline, micro-evaporators to concentrate and transport DNA targets to a nanoliter single molecule fluorescence detection chamber for subsequent molecular beacon probe hybridization and analysis. This use of solvent removal as a unique means of target transport in a microanalytical platform led to a greater than 5000-fold concentration enhancement and detection limits that pushed below the femtomolar barrier commonly reported using confocal fluorescence detection. This simple microliter-to-nanoliter interconnect for single molecule counting analysis resolved several common limitations, including the need for excessive fluorescent probe concentrations at low target levels and inefficiencies in direct handling of highly dilute biological samples. In this report, the hundreds of bacteria-specific DNA molecules contained in approximately 25 microliters of a 50 aM sample were shuttled to a four nanoliter detection chamber through micro-evaporation. Here, the previously undetectable targets were enhanced to the pM regime and underwent probe hybridization and highly-efficient fluorescent event analysis via microfluidic recirculation through the confocal detection volume. This use of microfluidics in a single molecule detection (SMD) platform delivered unmatched sensitivity and introduced compliment technologies that may serve to bring SMD to more widespread use in replacing conventional methodologies for detecting rare target biomolecules in both research and clinical labs. PMID:19350088

  3. Fermentative production of lactic acid from renewable materials: recent achievements, prospects, and limits.

    PubMed

    Wang, Ying; Tashiro, Yukihiro; Sonomoto, Kenji

    2015-01-01

    The development and implementation of renewable materials for the production of versatile chemical resources have gained considerable attention recently, as this offers an alternative to the environmental problems caused by the petroleum industry and the limited supply of fossil resources. Therefore, the concept of utilizing biomass or wastes from agricultural and industrial residues to produce useful chemical products has been widely accepted. Lactic acid plays an important role due to its versatile application in the food, medical, and cosmetics industries and as a potential raw material for the manufacture of biodegradable plastics. Currently, the fermentative production of optically pure lactic acid has increased because of the prospects of environmental friendliness and cost-effectiveness. In order to produce lactic acid with high yield and optical purity, many studies focus on wild microorganisms and metabolically engineered strains. This article reviews the most recent advances in the biotechnological production of lactic acid mainly by lactic acid bacteria, and discusses the feasibility and potential of various processes. PMID:25077706

  4. Recent advances on enzymatic glucose/oxygen and hydrogen/oxygen biofuel cells: Achievements and limitations

    NASA Astrophysics Data System (ADS)

    Cosnier, Serge; J. Gross, Andrew; Le Goff, Alan; Holzinger, Michael

    2016-09-01

    The possibility of producing electrical power from chemical energy with biological catalysts has induced the development of biofuel cells as viable energy sources for powering portable and implanted electronic devices. These power sources employ biocatalysts, called enzymes, which are highly specific and catalytic towards the oxidation of a biofuel and the reduction of oxygen or hydrogen peroxide. Enzymes, on one hand, are promising candidates to replace expensive noble metal-based catalysts in fuel cell research. On the other hand, they offer the exciting prospect of a new generation of fuel cells which harvest energy from body fluids. Biofuel cells which use glucose as a fuel are particularly interesting for generating electricity to power electronic devices inside a living body. Hydrogen consuming biofuel cells represent an emerging alternative to platinum catalysts due to comparable efficiencies and the capability to operate at lower temperatures. Currently, these technologies are not competitive with existing commercialised fuel cell devices due to limitations including insufficient power outputs and lifetimes. The advantages and challenges facing glucose biofuel cells for implantation and hydrogen biofuel cells will be summarised along with recent promising advances and the future prospects of these exotic energy-harvesting devices.

  5. A computational approach to achieve situational awareness from limited observations of a complex system

    NASA Astrophysics Data System (ADS)

    Sherwin, Jason

    At the start of the 21st century, the topic of complexity remains a formidable challenge in engineering, science and other aspects of our world. It seems that when disaster strikes it is because some complex and unforeseen interaction causes the unfortunate outcome. Why did the financial system of the world meltdown in 2008--2009? Why are global temperatures on the rise? These questions and other ones like them are difficult to answer because they pertain to contexts that require lengthy descriptions. In other words, these contexts are complex. But we as human beings are able to observe and recognize this thing we call 'complexity'. Furthermore, we recognize that there are certain elements of a context that form a system of complex interactions---i.e., a complex system. Many researchers have even noted similarities between seemingly disparate complex systems. Do sub-atomic systems bear resemblance to weather patterns? Or do human-based economic systems bear resemblance to macroscopic flows? Where do we draw the line in their resemblance? These are the kinds of questions that are asked in complex systems research. And the ability to recognize complexity is not only limited to analytic research. Rather, there are many known examples of humans who, not only observe and recognize but also, operate complex systems. How do they do it? Is there something superhuman about these people or is there something common to human anatomy that makes it possible to fly a plane? Or to drive a bus? Or to operate a nuclear power plant? Or to play Chopin's etudes on the piano? In each of these examples, a human being operates a complex system of machinery, whether it is a plane, a bus, a nuclear power plant or a piano. What is the common thread running through these abilities? The study of situational awareness (SA) examines how people do these types of remarkable feats. It is not a bottom-up science though because it relies on finding general principles running through a host of varied

  6. Keyhole electron diffractive imaging (KEDI).

    PubMed

    De Caro, Liberato; Carlino, Elvio; Vittoria, Fabio Alessio; Siliqi, Dritan; Giannini, Cinzia

    2012-11-01

    Electron diffractive imaging (EDI) relies on combining information from the high-resolution transmission electron microscopy image of an isolated kinematically diffracting nano-particle with the corresponding nano-electron diffraction pattern. Phase-retrieval algorithms allow one to derive the phase, lost in the acquisition of the diffraction pattern, to visualize the actual atomic projected potential within the specimen at sub-ångström resolution, overcoming limitations due to the electron lens aberrations. Here the approach is generalized to study extended crystalline specimens. The new technique has been called keyhole electron diffractive imaging (KEDI) because it aims to investigate nano-regions of extended specimens at sub-ångström resolution by properly confining the illuminated area. Some basic issues of retrieving phase information from the EDI/KEDI measured diffracted amplitudes are discussed. By using the generalized Shannon sampling theorem it is shown that whenever suitable oversampling conditions are satisfied, EDI/KEDI diffraction patterns can contain enough information to lead to reliable phase retrieval of the unknown specimen electrostatic potential. Hence, the KEDI method has been demonstrated by simulations and experiments performed on an Si crystal cross section in the [112] zone-axis orientation, achieving a resolution of 71 pm. PMID:23075611

  7. 2.5 kW monolithic continuous wave (CW) near diffraction-limited fiber laser at 1080 nm

    NASA Astrophysics Data System (ADS)

    Fang, Qiang; Shi, Wei; Qin, Yuguo; Meng, Xiangjie; Zhang, Qihang

    2014-10-01

    We demonstrate a monolithic continuous wave (CW) fiber laser source at 1080 nm, producing 2.5 kW average laser power with near diffraction-limited beam quality (M2 < 1.3). The laser consists of a CW fiber laser oscillator and one double cladding (DC) fiber amplifier in the master oscillator-power amplifier (MOPA) configuration. The optical-to-optical conversion efficiency of the entire laser system with respect to the launched pump power is ~77.9%.

  8. High-power ({gt}0.9 W cw) diffraction-limited semiconductor laser based on a fiber Bragg grating external cavity

    SciTech Connect

    Cornwell, D.M. , Jr.; Thomas, H.J.

    1997-02-01

    We have developed a high-power ({gt}0.9 W cw) diffraction-limited semiconductor laser based on a tapered semiconductor optical amplifier using a fiber Bragg grating in an external cavity configuration. Frequency-selective feedback from the fiber grating is injected into the amplifier via direct butt coupling through a single mode fiber, resulting in a spectrally stable and narrow ({lt}0.3 nm) high-power laser for solid-state laser pumping, laser remote sensing, and optical communications. {copyright} {ital 1997 American Institute of Physics.}

  9. Near-diffraction-limited,35.4 W laser-diode end-pumped Nd:YVO4 slab laser operating at 1342 nm.

    PubMed

    Yan, Ying; Zhang, Hengli; Liu, Yang; Yu, Xilong; Zhang, Huaijin; He, Jingliang; Xin, Jianguo

    2009-07-15

    A diode stack end-pumped Nd:YVO4 slab laser at 1342 nm with near-diffraction-limited beam quality by using a hybrid resonator was presented. At a pump power of 139.5 W, laser power of 35.4 W was obtained with a conversion efficiency of 25.4% of the laser diode to laser output. The beam quality M2 factors were measured to be 1.2 in the unstable direction and 1.3 in the stable direction at the output power of 29 W. PMID:19823516

  10. Trade-off study for high resolution spectroscopy in the near infrared with ELT telescopes: seeing-limited vs. diffraction limited instruments

    NASA Astrophysics Data System (ADS)

    Sanna, Nicoletta; Oliva, E.; Massi, Fabrizio; Cresci, G.; Origlia, L.

    2014-08-01

    HIRES, a high resolution spectrometer, is one of the first five instruments foreseen in the ESO roadmap for the E-ELT. This spectrograph should ideally provide full spectral coverage from the UV limit to 2.5 microns, with a resolving power from R˜10,000 to R˜100,000. At visual/blue wavelengths, where the adaptive optics (AO) cannot provide an efficient light-concentration, HIRES will necessarily be a bulky, seeing-limited instrument. The fundamental question, which we address in this paper, is whether the same approach should be adopted in the near-infrared range, or HIRES should only be equipped with compact infrared module(s) with a much smaller aperture, taking advantage of an AO-correction. The main drawbacks of a seeing-limited instrument at all wavelengths are: i) Lower sensitivities at wavelengths dominated by thermal background (red part of the K-band). ii) Much higher volumes and costs for the IR spectrograph module(s). The main drawbacks of using smaller, AO-fed IR module(s) are: i) Performances rapidly degrading towards shorter wavelengths (especially J e Y bands). ii) Different spatial sampling of extended objects (the optical module see a much larger area on the sky). In this paper we perform a trade-off analysis and quantify the various effects that contribute to improve or deteriorate the signal to noise ratio. In particular, we evaluate the position of the cross-over wavelength at which AO-fed instruments starts to outperform seeing-limited instruments. This parameter is of paramount importance for the design of the part of HIRES covering the K-band.

  11. Electrochemical flow injection analysis of hydrazine in an excess of an active pharmaceutical ingredient: achieving pharmaceutical detection limits electrochemically.

    PubMed

    Channon, Robert B; Joseph, Maxim B; Bitziou, Eleni; Bristow, Anthony W T; Ray, Andrew D; Macpherson, Julie V

    2015-10-01

    The quantification of genotoxic impurities (GIs) such as hydrazine (HZ) is of critical importance in the pharmaceutical industry in order to uphold drug safety. HZ is a particularly intractable GI and its detection represents a significant technical challenge. Here, we present, for the first time, the use of electrochemical analysis to achieve the required detection limits by the pharmaceutical industry for the detection of HZ in the presence of a large excess of a common active pharmaceutical ingredient (API), acetaminophen (ACM) which itself is redox active, typical of many APIs. A flow injection analysis approach with electrochemical detection (FIA-EC) is utilized, in conjunction with a coplanar boron doped diamond (BDD) microband electrode, insulated in an insulating diamond platform for durability and integrated into a two piece flow cell. In order to separate the electrochemical signature for HZ such that it is not obscured by that of the ACM (present in excess), the BDD electrode is functionalized with Pt nanoparticles (NPs) to significantly shift the half wave potential for HZ oxidation to less positive potentials. Microstereolithography was used to fabricate flow cells with defined hydrodynamics which minimize dispersion of the analyte and optimize detection sensitivity. Importantly, the Pt NPs were shown to be stable under flow, and a limit of detection of 64.5 nM or 0.274 ppm for HZ with respect to the ACM, present in excess, was achieved. This represents the first electrochemical approach which surpasses the required detection limits set by the pharmaceutical industry for HZ detection in the presence of an API and paves the wave for online analysis and application to other GI and API systems. PMID:26302058

  12. Going far beyond the near-field diffraction limit via plasmonic cavity lens with high spatial frequency spectrum off-axis illumination.

    PubMed

    Zhao, Zeyu; Luo, Yunfei; Zhang, Wei; Wang, Changtao; Gao, Ping; Wang, Yanqin; Pu, Mingbo; Yao, Na; Zhao, Chengwei; Luo, Xiangang

    2015-01-01

    For near-field imaging optics, minimum resolvable feature size is highly constrained by the near-field diffraction limit associated with the illumination light wavelength and the air distance between the imaging devices and objects. In this study, a plasmonic cavity lens composed of Ag-photoresist-Ag form incorporating high spatial frequency spectrum off-axis illumination (OAI) is proposed to realize deep subwavelength imaging far beyond the near-field diffraction limit. This approach benefits from the resonance effect of the plasmonic cavity lens and the wavevector shifting behavior via OAI, which remarkably enhances the object's subwavelength information and damps negative imaging contribution from the longitudinal electric field component in imaging region. Experimental images of well resolved 60-nm half-pitch patterns under 365-nm ultra-violet light are demonstrated at air distance of 80 nm between the mask patterns and plasmonic cavity lens, approximately four-fold longer than that in the conventional near-field lithography and superlens scheme. The ultimate air distance for the 60-nm half-pitch object could be theoretically extended to 120 nm. Moreover, two-dimensional L-shape patterns and deep subwavelength patterns are illustrated via simulations and experiments. This study promises the significant potential to make plasmonic lithography as a practical, cost-effective, simple and parallel nano-fabrication approach. PMID:26477856

  13. Delivery of 800 W of nearly diffraction-limited laser power through a 100 m long multi-mode fiber

    NASA Astrophysics Data System (ADS)

    Negel, Jan-Philipp; Austerschulte, Armin; Vogel, Moritz M.; Rataj, Thomas; Voss, Andreas; Abdou Ahmed, Marwan; Graf, Thomas

    2014-05-01

    We present the efficient propagation of a nearly diffraction-limited laser beam with a continuous wave power of 800 W through a multi-mode step-index delivery fiber with a core diameter of 30 µm and a numerical aperture of 0.056. The M2-value was measured to be 1.35 after 100 m of this passive fiber. This is an important advance as the delivery fiber length for high-brightness beams in the kilowatt range is usually limited to a few meters by the onset of nonlinear effects. For this demonstration a single-mode MOPA system was set-up consisting of a fiber oscillator and two amplifier stages. This source was coupled into the delivery fiber through a 500 mm long mode field adapter.

  14. Nearly diffraction-limited X-ray focusing with variable-numerical-aperture focusing optical system based on four deformable mirrors

    PubMed Central

    Matsuyama, Satoshi; Nakamori, Hiroki; Goto, Takumi; Kimura, Takashi; Khakurel, Krishna P.; Kohmura, Yoshiki; Sano, Yasuhisa; Yabashi, Makina; Ishikawa, Tetsuya; Nishino, Yoshinori; Yamauchi, Kazuto

    2016-01-01

    Unlike the electrostatic and electromagnetic lenses used in electron microscopy, most X-ray focusing optical systems have fixed optical parameters with constant numerical apertures (NAs). This lack of adaptability has significantly limited application targets. In the research described herein, we developed a variable-NA X-ray focusing system based on four deformable mirrors, two sets of Kirkpatrick–Baez-type focusing mirrors, in order to control the focusing size while keeping the position of the focus unchanged. We applied a mirror deformation procedure using optical/X-ray metrology for offline/online adjustments. We performed a focusing test at a SPring-8 beamline and confirmed that the beam size varied from 108 nm to 560 nm (165 nm to 1434 nm) in the horizontal (vertical) direction by controlling the NA while maintaining diffraction-limited conditions. PMID:27097853

  15. Nearly diffraction-limited X-ray focusing with variable-numerical-aperture focusing optical system based on four deformable mirrors

    NASA Astrophysics Data System (ADS)

    Matsuyama, Satoshi; Nakamori, Hiroki; Goto, Takumi; Kimura, Takashi; Khakurel, Krishna P.; Kohmura, Yoshiki; Sano, Yasuhisa; Yabashi, Makina; Ishikawa, Tetsuya; Nishino, Yoshinori; Yamauchi, Kazuto

    2016-04-01

    Unlike the electrostatic and electromagnetic lenses used in electron microscopy, most X-ray focusing optical systems have fixed optical parameters with constant numerical apertures (NAs). This lack of adaptability has significantly limited application targets. In the research described herein, we developed a variable-NA X-ray focusing system based on four deformable mirrors, two sets of Kirkpatrick–Baez-type focusing mirrors, in order to control the focusing size while keeping the position of the focus unchanged. We applied a mirror deformation procedure using optical/X-ray metrology for offline/online adjustments. We performed a focusing test at a SPring-8 beamline and confirmed that the beam size varied from 108 nm to 560 nm (165 nm to 1434 nm) in the horizontal (vertical) direction by controlling the NA while maintaining diffraction-limited conditions.

  16. Nearly diffraction-limited X-ray focusing with variable-numerical-aperture focusing optical system based on four deformable mirrors.

    PubMed

    Matsuyama, Satoshi; Nakamori, Hiroki; Goto, Takumi; Kimura, Takashi; Khakurel, Krishna P; Kohmura, Yoshiki; Sano, Yasuhisa; Yabashi, Makina; Ishikawa, Tetsuya; Nishino, Yoshinori; Yamauchi, Kazuto

    2016-01-01

    Unlike the electrostatic and electromagnetic lenses used in electron microscopy, most X-ray focusing optical systems have fixed optical parameters with constant numerical apertures (NAs). This lack of adaptability has significantly limited application targets. In the research described herein, we developed a variable-NA X-ray focusing system based on four deformable mirrors, two sets of Kirkpatrick-Baez-type focusing mirrors, in order to control the focusing size while keeping the position of the focus unchanged. We applied a mirror deformation procedure using optical/X-ray metrology for offline/online adjustments. We performed a focusing test at a SPring-8 beamline and confirmed that the beam size varied from 108 nm to 560 nm (165 nm to 1434 nm) in the horizontal (vertical) direction by controlling the NA while maintaining diffraction-limited conditions. PMID:27097853

  17. Achieving Stable Nitritation for Mainstream Deammonification by Combining Free Nitrous Acid-Based Sludge Treatment and Oxygen Limitation

    PubMed Central

    Wang, Dongbo; Wang, Qilin; Laloo, Andrew; Xu, Yifeng; Bond, Philip L.; Yuan, Zhiguo

    2016-01-01

    Stable nitritation is a critical bottleneck for achieving autotrophic nitrogen removal using the energy-saving mainstream deammonification process. Herein we report a new strategy to wash out both the Nitrospira sp. and Nitrobacter sp. from the treatment of domestic-strength wastewater. The strategy combines sludge treatment using free nitrous acid (FNA) with dissolved oxygen (DO) control in the nitritation reactor. Initially, the nitrifying reactor achieved full conversion of NH4+ to NO3−. Then, nitrite accumulation at ~60% was achieved in the reactor when 1/4 of the sludge was treated daily with FNA at 1.82 mg N/L in a side-stream unit for 24 h. Fluorescence in-situ hybridization (FISH) revealed FNA treatment substantially reduced the abundance of nitrite oxidizing bacteria (NOB) (from 23.0 ± 4.3 to 5.3 ± 1.9%), especially that of Nitrospira sp. (from 15.7 ± 3.9 to 0.4 ± 0.1%). Nitrite accumulation increased to ~80% when the DO concentration in the mainstream reactor was reduced from 2.5–3.0 to 0.3–0.8 mg/L. FISH revealed the DO limitation further reduced the abundance of NOB (to 2.1 ± 1.0%), especially that of Nitrobacter sp. (from 4.9 ± 1.2 to 1.8 ± 0.8%). The strategy developed removes a major barrier for deammonification in low-strength domestic wastewater. PMID:27151247

  18. Achieving Stable Nitritation for Mainstream Deammonification by Combining Free Nitrous Acid-Based Sludge Treatment and Oxygen Limitation

    NASA Astrophysics Data System (ADS)

    Wang, Dongbo; Wang, Qilin; Laloo, Andrew; Xu, Yifeng; Bond, Philip L.; Yuan, Zhiguo

    2016-05-01

    Stable nitritation is a critical bottleneck for achieving autotrophic nitrogen removal using the energy-saving mainstream deammonification process. Herein we report a new strategy to wash out both the Nitrospira sp. and Nitrobacter sp. from the treatment of domestic-strength wastewater. The strategy combines sludge treatment using free nitrous acid (FNA) with dissolved oxygen (DO) control in the nitritation reactor. Initially, the nitrifying reactor achieved full conversion of NH4+ to NO3‑. Then, nitrite accumulation at ~60% was achieved in the reactor when 1/4 of the sludge was treated daily with FNA at 1.82 mg N/L in a side-stream unit for 24 h. Fluorescence in-situ hybridization (FISH) revealed FNA treatment substantially reduced the abundance of nitrite oxidizing bacteria (NOB) (from 23.0 ± 4.3 to 5.3 ± 1.9%), especially that of Nitrospira sp. (from 15.7 ± 3.9 to 0.4 ± 0.1%). Nitrite accumulation increased to ~80% when the DO concentration in the mainstream reactor was reduced from 2.5–3.0 to 0.3–0.8 mg/L. FISH revealed the DO limitation further reduced the abundance of NOB (to 2.1 ± 1.0%), especially that of Nitrobacter sp. (from 4.9 ± 1.2 to 1.8 ± 0.8%). The strategy developed removes a major barrier for deammonification in low-strength domestic wastewater.

  19. Achieving Stable Nitritation for Mainstream Deammonification by Combining Free Nitrous Acid-Based Sludge Treatment and Oxygen Limitation.

    PubMed

    Wang, Dongbo; Wang, Qilin; Laloo, Andrew; Xu, Yifeng; Bond, Philip L; Yuan, Zhiguo

    2016-01-01

    Stable nitritation is a critical bottleneck for achieving autotrophic nitrogen removal using the energy-saving mainstream deammonification process. Herein we report a new strategy to wash out both the Nitrospira sp. and Nitrobacter sp. from the treatment of domestic-strength wastewater. The strategy combines sludge treatment using free nitrous acid (FNA) with dissolved oxygen (DO) control in the nitritation reactor. Initially, the nitrifying reactor achieved full conversion of NH4(+) to NO3(-). Then, nitrite accumulation at ~60% was achieved in the reactor when 1/4 of the sludge was treated daily with FNA at 1.82 mg N/L in a side-stream unit for 24 h. Fluorescence in-situ hybridization (FISH) revealed FNA treatment substantially reduced the abundance of nitrite oxidizing bacteria (NOB) (from 23.0 ± 4.3 to 5.3 ± 1.9%), especially that of Nitrospira sp. (from 15.7 ± 3.9 to 0.4 ± 0.1%). Nitrite accumulation increased to ~80% when the DO concentration in the mainstream reactor was reduced from 2.5-3.0 to 0.3-0.8 mg/L. FISH revealed the DO limitation further reduced the abundance of NOB (to 2.1 ± 1.0%), especially that of Nitrobacter sp. (from 4.9 ± 1.2 to 1.8 ± 0.8%). The strategy developed removes a major barrier for deammonification in low-strength domestic wastewater. PMID:27151247

  20. Possibilities and limitations of synchrotron X-ray powder diffraction with double crystal and double multilayer monochromators for microscopic speciation studies

    NASA Astrophysics Data System (ADS)

    De Nolf, Wout; Jaroszewicz, Jakub; Terzano, Roberto; Lind, Ole Christian; Salbu, Brit; Vekemans, Bart; Janssens, Koen; Falkenberg, Gerald

    2009-08-01

    The performance of a combined microbeam X-ray fluorescence/X-ray powder diffraction (XRF/XRPD) measurement station at Hamburger Synchrotronstrahlungslabor (HASYLAB) Beamline L is discussed in comparison to that at European Synchrotron Radiation Facility (ESRF) ID18F/ID22. The angular resolution in the X-ray diffractograms is documented when different combinations of X-ray source, optics and X-ray diffraction detectors are employed. Typical angular resolution values in the range 0.3-0.5° are obtained at the bending magnet source when a 'pink' beam form of excitation is employed. A similar setup at European Synchrotron Radiation Facility beamlines ID18F and ID22 allows to reach angular resolution values of 0.1-0.15°. In order to document the possibilities and limitations for speciation of metals in environmental materials by means of Hamburger Synchrotronstrahlungslabor Beamline L X-ray fluorescence/X-ray powder diffraction setup, two case studies are discussed, one involved in the identification of the crystal phases in which heavy metals such as chromium, iron, barium and lead are present in polluted soils of an industrial site (Val Basento, Italy) and another involved in the speciation of uranium in depleted uranium particles (Ceja Mountains, Kosovo). In the former case, the angular resolution is sufficient to allow identification of most crystalline phases present while in the latter case, it is necessary to dispose of an angular resolution of ca. 0.2° to distinguish between different forms of oxidized uranium.

  1. Pulse requirements for electron diffraction imaging of single biological molecules

    SciTech Connect

    Hau-Riege, S; London, R; Chapman, H

    2004-10-20

    The pulse requirements for electron diffraction imaging of single biological molecules are calculated. We find that the electron fluence and pulse length requirements imposed by the damage limit and by the need to classify the diffraction patterns according to their angular orientation cannot be achieved with today's electron beam technology. A simple analytical model shows that the pulse requirements cannot be achieved due to beam broadening due to spacecharge effects.

  2. The light-matter interaction of a single semiconducting AlGaN nanowire and noble metal Au nanoparticles in the sub-diffraction limit.

    PubMed

    Sivadasan, A K; Madapu, Kishore K; Dhara, Sandip

    2016-08-24

    Near field scanning optical microscopy (NSOM) is not only a tool for imaging of sub-diffraction limited objects but also a prominent characteristic tool for understanding the intrinsic properties of nanostructures. In order to understand light-matter interactions in the near field regime using a NSOM technique with an excitation of 532 nm (2.33 eV), we selected an isolated single semiconducting AlGaN nanowire (NW) of diameter ∼120 nm grown via a vapor liquid solid (VLS) mechanism along with a metallic Au nanoparticle (NP) catalyst. The role of electronic transitions from different native defect related energy states of AlGaN is discussed in understanding the NSOM images for the semiconducting NW. The effect of strong surface plasmon resonance absorption of an excitation laser on the NSOM images for Au NPs, involved in the VLS growth mechanism of NWs, is also observed. PMID:27511614

  3. Methodology for optimal in situ alignment and setting of bendable optics for diffraction-limited focusing of soft x-rays

    NASA Astrophysics Data System (ADS)

    Merthe, Daniel J.; Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Kunz, Martin; Tamura, Nobumichi; McKinney, Wayne R.; Artemiev, Nikolay A.; Celestre, Richard S.; Morrison, Gregory Y.; Anderson, Erik; Smith, Brian V.; Domning, Edward E.; Rekawa, Senajith B.; Padmore, Howard A.

    2012-09-01

    We demonstrate a comprehensive and broadly applicable methodology for the optimal in situ configuration of bendable soft x-ray Kirkpatrick-Baez mirrors. The mirrors used for this application are preset at the ALS Optical Metrology Laboratory prior to beamline installation. The in situ methodology consists of a new technique for simultaneously setting the height and pitch angle of each mirror. The benders of both mirrors were then optimally tuned in order to minimize ray aberrations to a level below the diffraction-limited beam waist size of 200 nm (horizontal) × 100 nm (vertical). After applying this methodology, we measured a beam waist size of 290 nm (horizontal) × 130 nm (vertical) with 1 nm light using the Foucault knife-edge test. We also discuss the utility of using a grating-based lateral shearing interferometer with quantitative wavefront feedback for further improvement of bendable optics.

  4. Methodology for optimal in situ alignment and setting of bendable optics for nearly diffraction-limited focusing of soft x-rays

    NASA Astrophysics Data System (ADS)

    Merthe, Daniel J.; Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Kunz, Martin; Tamura, Nobumichi; McKinney, Wayne R.; Artemiev, Nikolay A.; Celestre, Richard S.; Morrison, Gregory Y.; Anderson, Erik H.; Smith, Brian V.; Domning, Edward E.; Rekawa, Senajith B.; Padmore, Howard A.

    2013-03-01

    We demonstrate a comprehensive and broadly applicable methodology for the optimal in situ configuration of bendable soft x-ray Kirkpatrick-Baez mirrors. The mirrors used for this application are preset at the Advanced Light Source Optical Metrology Laboratory prior to beamline installation. The in situ methodology consists of a new technique for simultaneously setting the height and pitch angle of each mirror. The benders of both mirrors were then optimally tuned in order to minimize ray aberrations to a level below the diffraction-limited beam waist size of 200 nm (horizontal)×100 nm (vertical). After applying this methodology, we measured a beam waist size of 290 nm (horizontal)×130 nm (vertical) with 1 nm light using the Foucault knife-edge test. We also discuss the utility of using a grating-based lateral shearing interferometer with quantitative wavefront feedback for further improvement of bendable optics.

  5. Diode-side-pumped Nd:YLiF4 laser emitting at 1053 nm with 53.6% optical efficiency and diffraction-limited beam quality

    NASA Astrophysics Data System (ADS)

    Wetter, Niklaus U.; Deana, Alessandro M.

    2013-03-01

    We present a Nd:YLiF4 diode-side-pumped resonator architecture based on a gain-guided, mode-selective technique that employs a double pass of the fundamental laser mode through the crystal. The folded cavity is very compact, robust and cost efficient. With this design we demonstrate 19 W of quasi-cw, stable diffraction-limited laser emission at 1053 nm when pumping at 792 nm with 35.4 W. The slope efficiency of the laser is 65.3% and the optical-to-optical efficiency is 53.6%, which is, to the best of our knowledge, the highest efficiency reported for Nd:YLiF4 lasers pumped into the 4F5/2 band, including longitudinal pumping schemes and lasers emitting at the higher gain line of 1047 nm.

  6. Harmonic diffractive lenses

    SciTech Connect

    Sweeney, D.W.; Sommargren, G.E.

    1995-05-10

    The harmonic diffractive lens is a diffractive imaging lens for which the optical path-length transition between adjacent facets is an integer multiple {ital m} of the design wavelength {lambda}{sub 0}. The total lens thickness in air is {ital m}{lambda}{sub 0}/({ital n} {minus} 1), which is {ital m} times thicker than the so-called modulo 2{pi} diffractive lens. Lenses constructed in this way have hybrid properties of both refractive and diffractive lenses. Such a lens will have a diffraction-limited, common focus for a number of discrete wavelengths across the visible spectrum. A 34.75-diopter, 6-mm-diameter lens is diamond turned in aluminum and replicated in optical materials. The sag of the lens is 23 {mu}m. Modulation transfer function measurements in both monochromatic and white light verify the performance of the lens. The lens approaches the diffraction limit for 10 discrete wavelengths across the visible spectrum.

  7. Limiter

    DOEpatents

    Cohen, S.A.; Hosea, J.C.; Timberlake, J.R.

    1984-10-19

    A limiter with a specially contoured front face is provided. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution. This limiter shape accommodates the various power scrape-off distances lambda p, which depend on the parallel velocity, V/sub parallel/, of the impacting particles.

  8. 1 kW cw Yb-fiber-amplifier with <0.5GHz linewidth and near-diffraction limited beam-quality for coherent combining application

    NASA Astrophysics Data System (ADS)

    Engin, Doruk; Lu, Wei; Akbulut, Mehmetcan; McIntosh, Bruce; Verdun, Horacio; Gupta, Shantanu

    2011-02-01

    In this paper, we present results on a master-oscillator Yb-doped fiber amplifier with 1 kW cw output power (at 1064nm), and near-diffraction limited beam quality (M2<1.4), with internal quantum efficiency >83%. The final amplifier stage uses a very high Yb-doped 35-um core LMA fiber, using a new process recipe that virtually eliminates photo-darkening. As a result, high efficiency, SBS-free operation to 1 kW cw power level is obtained, with a phase modulation bandwidth of only 450MHz, well below other reported results. To enable single-frequency cw power scaling to kW levels, we investigate LMA fiber waveguide designs exploiting gain-discrimination, using partially Yb-doped LMA fiber cores, with various diameters up to 80-um. SBS-free, singlefrequency (few kHz) operation is demonstrated up to 0.9kW cw power. At the lower cw powers (<200W) neardiffraction limited beam-quality is obtained, but is observed to deteriorate at higher cw powers. We discuss potential causes, and present a detailed simulation model of kW large-core fiber-amplifiers, that includes all guided modes, fiber bend, transverse spatial hole burning, gain-tailoring, mode-scattering, SBS nonlinearity, and various thermal effects. This model shows good agreement with the observed single-frequency power scaling and beam-quality characteristics.

  9. A Descriptive Analysis of Enrollment and Achievement among Limited English Proficient Students in New Jersey. Summary. Issues & Answers. REL 2012-No. 108

    ERIC Educational Resources Information Center

    O'Conner, Rosemarie; Abedi, Jamal; Tung, Stephanie

    2012-01-01

    This study describes enrollment and achievement trends of limited English proficient (LEP) students in New Jersey public schools between 2002/03 and 2008/09. It documents achievement gaps between LEP and general education students in language arts literacy and math. The study's main findings include: (1) From 2002/03 to 2008/09, LEP student…

  10. Limiter

    DOEpatents

    Cohen, Samuel A.; Hosea, Joel C.; Timberlake, John R.

    1986-01-01

    A limiter with a specially contoured front face accommodates the various power scrape-off distances .lambda..sub.p, which depend on the parallel velocity, V.sub..parallel., of the impacting particles. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution.

  11. Imaging outside the box: Resolution enhancement in X-ray coherent diffraction imaging by extrapolation of diffraction patterns

    SciTech Connect

    Latychevskaia, Tatiana Fink, Hans-Werner; Chushkin, Yuriy; Zontone, Federico

    2015-11-02

    Coherent diffraction imaging is a high-resolution imaging technique whose potential can be greatly enhanced by applying the extrapolation method presented here. We demonstrate the enhancement in resolution of a non-periodical object reconstructed from an experimental X-ray diffraction record which contains about 10% missing information, including the pixels in the center of the diffraction pattern. A diffraction pattern is extrapolated beyond the detector area and as a result, the object is reconstructed at an enhanced resolution and better agreement with experimental amplitudes is achieved. The optimal parameters for the iterative routine and the limits of the extrapolation procedure are discussed.

  12. Eyeglass: A Very Large Aperture Diffractive Space Telescope

    SciTech Connect

    Hyde, R; Dixit, S; Weisberg, A; Rushford, M

    2002-07-29

    Eyeglass is a very large aperture (25-100 meter) space telescope consisting of two distinct spacecraft, separated in space by several kilometers. A diffractive lens provides the telescope's large aperture, and a separate, much smaller, space telescope serves as its mobile eyepiece. Use of a transmissive diffractive lens solves two basic problems associated with very large aperture space telescopes; it is inherently fieldable (lightweight and flat, hence packagable and deployable) and virtually eliminates the traditional, very tight, surface shape tolerances faced by reflecting apertures. The potential drawback to use of a diffractive primary (very narrow spectral bandwidth) is eliminated by corrective optics in the telescope's eyepiece. The Eyeglass can provide diffraction-limited imaging with either single-band, multiband, or continuous spectral coverage. Broadband diffractive telescopes have been built at LLNL and have demonstrated diffraction-limited performance over a 40% spectral bandwidth (0.48-0.72 {micro}m). As one approach to package a large aperture for launch, a foldable lens has been built and demonstrated. A 75 cm aperture diffractive lens was constructed from 6 panels of 1 m thick silica; it achieved diffraction-limited performance both before and after folding. This multiple panel, folding lens, approach is currently being scaled-up at LLNL. We are building a 5 meter aperture foldable lens, involving 72 panels of 700 {micro}m thick glass sheets, diffractively patterned to operate as coherent f/50 lens.

  13. Multilayer dielectric diffraction gratings

    DOEpatents

    Perry, Michael D.; Britten, Jerald A.; Nguyen, Hoang T.; Boyd, Robert; Shore, Bruce W.

    1999-01-01

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

  14. Multilayer dielectric diffraction gratings

    DOEpatents

    Perry, M.D.; Britten, J.A.; Nguyen, H.T.; Boyd, R.; Shore, B.W.

    1999-05-25

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described. 7 figs.

  15. Diode-pumped dual-wavelength Nd:LSO laser at 1059 and 1067  nm with nearly diffraction-limited beam quality.

    PubMed

    Huang, Xiaoxu; Lan, Jinglong; Lin, Zhi; Wang, Yi; Xu, Bin; Xu, Huiying; Cai, Zhiping; Xu, Xiaodong; Zhang, Jian; Xu, Jun

    2016-04-10

    We report a diode-pumped continuous-wave simultaneous dual-wavelength Nd:LSO laser at 1059 and 1067 nm. By employing a specially coated output coupler with relatively high transmissions at high-gain emission lines of 1075 and 1079 nm, the two low-gain emission lines, 1059 and 1067 nm, can be achieved, for the first time to our knowledge, with maximum output power of 1.27 W and slope efficiency of about 29.2%. The output power is only limited by the available pump power. Output beam quality is also measured to be about 1.19 and 1.21 of the beam propagation factors in the x and y directions, respectively. PMID:27139868

  16. The close circumstellar environment of Betelgeuse. II. Diffraction-limited spectro-imaging from 7.76 to 19.50 μm with VLT/VISIR

    NASA Astrophysics Data System (ADS)

    Kervella, P.; Perrin, G.; Chiavassa, A.; Ridgway, S. T.; Cami, J.; Haubois, X.; Verhoelst, T.

    2011-07-01

    Context. Mass-loss occurring in red supergiants (RSGs) is a major contributor to the enrichment of the interstellar medium in dust and molecules. The physical mechanism of this mass loss is however relatively poorly known. Betelgeuse is the nearest RSG, and as such a prime object for high angular resolution observations of its surface (by interferometry) and close circumstellar environment. Aims: The goal of our program is to understand how the material expelled from Betelgeuse is transported from its surface to the interstellar medium, and how it evolves chemically in this process. Methods: We obtained diffraction-limited images of Betelgeuse and a calibrator (Aldebaran) in six filters in the N band (7.76 to 12.81 μm) and two filters in the Q band (17.65 and 19.50 μm), using the VLT/VISIR instrument. Results: Our images show a bright, extended and complex circumstellar envelope at all wavelengths. It is particularly prominent longwards of ≈ 9-10 μm, pointing at the presence of O-rich dust, such as silicates or alumina. A partial circular shell is observed between 0.5 and 1.0″ from the star, and could correspond to the inner radius of the dust envelope. Several knots and filamentary structures are identified in the nebula. One of the knots, located at a distance of 0.9″ west of the star, is particularly bright and compact. Conclusions: The circumstellar envelope around Betelgeuse extends at least up to several tens of stellar radii. Its relatively high degree of clumpiness indicates an inhomogeneous spatial distribution of the material lost by the star. Its extension corresponds to an important intermediate scale, where most of the dust is probably formed, between the hot and compact gaseous envelope observed previously in the near infrared and the interstellar medium. Based on observations made with ESO telescopes at Paranal Observatory, under ESO DDT program 286.D-5007(A).

  17. Limits on Achievable Dimensional and Photon Efficiencies with Intensity-Modulation and Photon-Counting Due to Non-Ideal Photon-Counter Behavior

    NASA Technical Reports Server (NTRS)

    Moision, Bruce; Erkmen, Baris I.; Farr, William; Dolinar, Samuel J.; Birnbaum, Kevin M.

    2012-01-01

    An ideal intensity-modulated photon-counting channel can achieve unbounded photon information efficiencies (PIEs). However, a number of limitations of a physical system limit the practically achievable PIE. In this paper, we discuss several of these limitations and illustrate their impact on the channel. We show that, for the Poisson channel, noise does not strictly bound PIE, although there is an effective limit, as the dimensional information efficiency goes as e[overline] e PIE beyond a threshold PIE. Since the Holevo limit is bounded in the presence of noise, this illustrates that the Poisson approximation is invalid at large PIE for any number of noise modes. We show that a finite transmitter extinction ratio bounds the achievable PIE to a maximum that is logarithmic in the extinction ratio. We show how detector jitter limits the ability to mitigate noise in the PPM signaling framework. We illustrate a method to model detector blocking when the number of detectors is large, and illustrate mitigation of blocking with spatial spreading and altering. Finally, we illustrate the design of a high photon efficiency system using state-of-the-art photo-detectors and taking all these effects into account.

  18. Native Language Proficiency, English Literacy, Academic Achievement, and Occupational Attainment in Limited-English-Proficient Students: A Latent Growth Modeling Perspective

    ERIC Educational Resources Information Center

    Guglielmi, R. Sergio

    2008-01-01

    The hypothesis that native language (L1) proficiency promotes English acquisition and overall academic achievement, a key theoretical assumption underlying bilingual education, was tested using latent growth modeling of data from 899 limited-English-proficient (LEP) eighth graders who were followed for 12 years in the National Education…

  19. Differences in Reading and Math Achievement among Students Who Are Hispanic, Limited English Proficient, or White: A Multi-Year Study

    ERIC Educational Resources Information Center

    Rojas-LeBouef, Ana M.

    2010-01-01

    Purpose. The purpose of this study was to examine differences in academic achievement among students who were Hispanic, Limited English Proficient (LEP), or White, using archival data from the Texas Education Agency's (TEA) Academic Excellence Indicator System (AEIS). Data examined were fifth grade reading and math passing rates from the 1993…

  20. Reframing the Conversation about Students with Limited or Interrupted Formal Education: From Achievement Gap to Cultural Dissonance

    ERIC Educational Resources Information Center

    DeCapua, Andrea; Marshall, Helaine W.

    2015-01-01

    U.S. schools face increasing pressure to ensure that all students succeed, yet the dropout rate for English learners is alarmingly high, especially for those with limited or interrupted formal schooling (SLIFE). Serving SLIFE can be challenging because they not only need to master language and content but also need to develop literacy skills and…

  1. Improving Academic Achievement through Building Self-Esteem in At-Risk Limited English Proficient Ninth Grade Haitian Students.

    ERIC Educational Resources Information Center

    Myrick, Gloria H.

    A self-esteem building program was developed and implemented to reduce the failure and potential dropout rate of limited English proficient 9th-grade Haitian students (N=15) who were enrolled in bilingual classes and were selected based on recommendations from their bilingual teachers, referrals for behavior problems, and failure in two or more…

  2. Limited knowledge of fraction representations differentiates middle school students with mathematics learning disability (dyscalculia) vs. low mathematics achievement

    PubMed Central

    Mazzocco, Michèle M. M.; Myers, Gwen F.; Lewis, Katherine E.; Hanich, Laurie B.; Murphy, Melissa M.

    2014-01-01

    Fractions pose significant challenges for many children, but for some children those challenges persist into high school. Here we administered a fractions magnitude comparison test to 122 children, from Grades 4 to 8, to test whether their knowledge of fractions typically learned early in the sequence of formal math instruction (e.g., fractions equivalent to “one-half,” and fraction pairs with common denominators) differentiates those with mathematical learning disability (MLD) versus low achievement (LA) or typical achievement (TA) in mathematics, and whether long term learning trajectories of this knowledge also differentiate these groups. We confirmed that although 4th graders with LA (n = 18) or TA (n = 93) are more accurate evaluating one-half vs. non-half fractions (until they reach ceiling performance levels on both types of fractions), children with MLD (n=11) do not show a one-half advantage until Grade 7 and do not reach ceiling performance even by Grade 8. Both the MLD and LA groups have early difficulties with fractions, but by Grade 5 the LA group approaches performance levels of the TA group and deviates from the MLD group. All groups showed a visual model advantage over Arabic number representation of fractions, but this advantage was short lived for the TA group (because ceiling level was achieved across formats), slightly more persistent for the LA group, and persisted through Grade 8 for children with MLD. Thus, difficulties with fractions persist through Grade 8 for many students, but the nature and trajectories of those difficulties varies across children with math difficulties (MLD or LA). PMID:23587941

  3. Limited knowledge of fraction representations differentiates middle school students with mathematics learning disability (dyscalculia) versus low mathematics achievement.

    PubMed

    Mazzocco, Michèle M M; Myers, Gwen F; Lewis, Katherine E; Hanich, Laurie B; Murphy, Melissa M

    2013-06-01

    Fractions pose significant challenges for many children, but for some children those challenges persist into high school. Here we administered a fractions magnitude comparison test to 122 children, from Grades 4 to 8, to test whether their knowledge of fractions typically learned early in the sequence of formal math instruction (e.g., fractions equivalent to one-half, fraction pairs with common denominators) differentiates those with mathematics learning disability (MLD) versus low achievement (LA) or typical achievement (TA) in mathematics and whether long-term learning trajectories of this knowledge also differentiate these groups. We confirmed that although fourth graders with TA (n=93) were more accurate in evaluating "one-half" fractions than in evaluating "non-half" fractions (until they reached ceiling performance levels on both types of fractions), children with MLD (n=11) did not show a one-half advantage until Grade 7 and did not reach ceiling performance even by Grade 8. Both the MLD and LA groups had early difficulties with fractions, but by Grade 5 the LA group approached performance levels of the TA group and deviated from the MLD group. All groups showed a visual model advantage over Arabic number representation of fractions, but this advantage was short-lived for the TA group (because ceiling level was achieved across formats), whereas it was slightly more persistent for the LA group and persisted through Grade 8 for children with MLD. Thus, difficulties with fractions persist through Grade 8 for many students, but the nature and trajectories of those difficulties vary across children with math difficulties (MLD or LA). PMID:23587941

  4. Chromatic confocal microscope using hybrid aspheric diffractive lenses

    NASA Astrophysics Data System (ADS)

    Rayer, Mathieu; Mansfield, Daniel

    2014-05-01

    A chromatic confocal microscope is a single point non-contact distance measurement sensor. For three decades the vast majority of the chromatic confocal microscope use refractive-based lenses to code the measurement axis chromatically. However, such an approach is limiting the range of applications. In this paper the performance of refractive, diffractive and Hybrid aspheric diffractive are compared. Hybrid aspheric diffractive lenses combine the low geometric aberration of a diffractive lens with the high optical power of an aspheric lens. Hybrid aspheric diffractive lenses can reduce the number of elements in an imaging system significantly or create large hyper- chromatic lenses for sensing applications. In addition, diffractive lenses can improve the resolution and the dynamic range of a chromatic confocal microscope. However, to be suitable for commercial applications, the diffractive optical power must be significant. Therefore, manufacturing such lenses is a challenge. We show in this paper how a theoretical manufacturing model can demonstrate that the hybrid aspheric diffractive configuration with the best performances is achieved by step diffractive surface. The high optical quality of step diffractive surface is then demonstrated experimentally. Publisher's Note: This paper, originally published on 5/10/14, was replaced with a corrected/revised version on 5/19/14. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance.

  5. A new design approach to achieve a minimum impulse limit cycle in the presence of significant measurement uncertainties

    NASA Technical Reports Server (NTRS)

    Martin, M. W.; Kubiak, E. T.

    1982-01-01

    A new design was developed for the Space Shuttle Transition Phase Digital Autopilot to reduce the impact of large measurement uncertainties in the rate signal during attitude control. The signal source, which was dictated by early computer constraints, is characterized by large quantization, noise, bias, and transport lag which produce a measurement uncertainty larger than the minimum impulse rate change. To ensure convergence to a minimum impulse limit cycle, the design employed bias and transport lag compensation and a switching logic with hysteresis, rate deadzone, and 'walking' switching line. The design background, the rate measurement uncertainties, and the design solution are documented.

  6. Limits imposed by solenoid damage on the maximum velocity achieved by an electromagnetic coilgun: A computational study

    NASA Astrophysics Data System (ADS)

    Madhavan, S.; Sijoy, C. D.; Pahari, S.; Chaturvedi, S.

    2012-06-01

    CAD has set up an electromagnetic acceleration and impact facility for studies of material fracture and deformation at high strain rates. The target is to reach projectile velocities of 200-500 m/s. The mechanical strength of the solenoid coil and potting material is an important factor affecting coil survival during experiments. We have performed a computational study, using the materials and coil and circuit parameters typically used in experiments, and found the operating limits up to which the coil can survive without breaking.

  7. Critical factors for achieving multiple goals with water tariff systems: Combining limited data sources and expert testimony

    NASA Astrophysics Data System (ADS)

    Dalhuisen, Jasper; Nijkamp, Peter

    2002-07-01

    Price instruments are well-known policy handles to influence effectively residential water demand. Prices used to be set by water authorities in such a way that the principle of cost coverage was respected; they acted as prominent instruments in residential water policies in the past decades. More recently, however, price instruments are increasingly used to meet simultaneously financial, environmental, and social goals. This paper addresses four conditions for an appropriate tariff system for residential water use which are often found in the recent literature on the economics of water use. The paper analyzes the importance of background factors (e.g., low water availability) of these four principles as well as the extent to which actual tariff systems are employed in five mutually contrasting cities (Amsterdam, Athens, London, Seville, and Tel Aviv). Meta-analytic techniques, in particular, rough set analysis stemming from artificial intelligence, are applied to identify the common underlying relations between background factors and success of achieving multiple goals in these five urban case studies. The paper concludes with policy recommendations.

  8. Energy extraction and achievement of the saturation limit in a discharge pumped table-top soft x-ray amplifier.

    NASA Astrophysics Data System (ADS)

    Rocca, J. J.; Clark, D. P.; Chilla, J. L. A.; Shlyaptsev, V. N.; Marconi, M. C.

    1996-11-01

    There is significant interest in the demonstration of compact soft x-ray amplifiers capable of generating pulses of substantial energy for applications. This motivates the demonstration of gain media generated by compact devices, that can be successfully scaled in length to reach gain saturation. To date, gain saturation had only been achieved in a few soft x-ray laser lines in plasmas generated by some of the world's largest laser facilities.(B. J. MacGowan et al.), Phys. Fluids B 4, 2326 (1992); A. Carillon et al., Phys. Rev. Lett 68, 2917 (1992);B. Rus et al., in AIP Conf. Proc. 332, X-ray lasers 1994, p. 152; S. Wang et al., ibid., p. 293. Previosly we reported large amplification at 46.9 nm in Ne-like argon in a plasma column generated by a fast capillary discharge.(J. J. Rocca et al.), Phys. Rev. Lett. 73, 2192 (1994). Herein we report the generation of laser pulse energies up to 30 μJ at 46.9 nm in such discharge and the first clear evidence of gain saturation of a table-top soft x-ray amplifier. Single pass amplification experiments yielded laser pulse energies up to 6 μJ and double pass amplification using an iridium mirror yielded 30 μJ. The observed saturation of the gain and laser pulse energy are in good agreement with the results of radiation transport calculations. Work supported by the National Science Foundation.

  9. Design of infrared diffractive telescope imaging optical systems

    NASA Astrophysics Data System (ADS)

    Zhang, ZhouFeng; Hu, BingLiang; Yin, QinYe; Xie, YongJun; Kang, FuZeng; Wang, YanJun

    2015-10-01

    Diffractive telescope is an updated imaging technology, it differs from conventional refractive and reflective imaging system, which is based on the principle of diffraction image. It has great potential for developing the larger aperture and lightweight telescope. However, one of the great challenges of design this optical system is that the diffractive optical element focuses on different wavelengths of light at different point in space, thereby distorting the color characteristics of image. In this paper, we designs a long-wavelength infrared diffractive telescope imaging system with flat surface Fresnel lens and cancels the infrared optical system chromatic aberration by another flat surface Fresnel lens, achieving broadband light(from 8μm-12μm) to a common focus with 4.6° field of view. At last, the diffuse spot size and MTF function provide diffractive-limited performance.

  10. Nuclear Symbiosis - A Means to Achieve Sustainable Nuclear Growth while Limiting the Spread of Sensititive Nuclear Technology

    SciTech Connect

    David Shropshire

    2009-09-01

    Global growth of nuclear energy in the 21st century is creating new challenges to limit the spread of nuclear technology without hindering adoption in countries now considering nuclear power. Independent nuclear states desire autonomy over energy choices and seek energy independence. However, this independence comes with high costs for development of new indigenous fuel cycle capabilities. Nuclear supplier states and expert groups have proposed fuel supply assurance mechanisms such as fuel take-back services, international enrichment services and fuel banks in exchange for recipient state concessions on the development of sensitive technologies. Nuclear states are slow to accept any concessions to their rights under the Non-Proliferation Treaty. To date, decisions not to develop indigenous fuel cycle capabilities have been driven primarily by economics. However, additional incentives may be required to offset a nuclear state’s perceived loss of energy independence. This paper proposes alternative economic development incentives that could help countries decide to forgo development of sensitive nuclear technologies. The incentives are created through a nuclear-centered industrial complex with “symbiotic” links to indigenous economic opportunities. This paper also describes a practical tool called the “Nuclear Materials Exchange” for identifying these opportunities.

  11. Spectral diffraction efficiency characterization of broadband diffractive optical elements.

    SciTech Connect

    Choi, Junoh; Cruz-Cabrera, Alvaro Augusto; Tanbakuchi, Anthony

    2013-03-01

    Diffractive optical elements, with their thin profile and unique dispersion properties, have been studied and utilized in a number of optical systems, often yielding smaller and lighter systems. Despite the interest in and study of diffractive elements, the application has been limited to narrow spectral bands. This is due to the etch depths, which are optimized for optical path differences of only a single wavelength, consequently leading to rapid decline in efficiency as the working wavelength shifts away from the design wavelength. Various broadband diffractive design methodologies have recently been developed that improve spectral diffraction efficiency and expand the working bandwidth of diffractive elements. We have developed diffraction efficiency models and utilized the models to design, fabricate, and test two such extended bandwidth diffractive designs.

  12. Metagratings for Diffraction Based, Compact, Holographic Imaging

    NASA Astrophysics Data System (ADS)

    Inampudi, Sandeep; Podolskiy, Viktor; Multiscale Electromagnetics Group Team

    2013-03-01

    Recent developments in semiconductor technology brought to life a new generation of highly-compact visible-frequency cameras. Unfortunately, straight forward extension of this progress to low-frequency domains (such as mid-IR imaging) is impossible since the pixel size at these frequencies is limited by free-space diffraction limit. Here we present an approach to realize highly-compact imaging systems at lower frequencies. Our approach takes advantage of high refractive index of materials commonly utilized in semiconductor detectors of mid-IR radiation, accompanied by metagratings, structures with engineered diffraction properties, to achieve a 10-fold reduction in the pixel size. In contrast to conventional refraction-based imaging, the approach essentially produces a digital hologram - a 2D projection of the 3D optical field, enabling a post-imaging ``refocusing'' of the picture. The perspectives of numerical recovery of the optical field and the stability of such recovery are discussed.

  13. Testing the limits of sensitivity in a solid-state structural investigation by combined X-ray powder diffraction, solid-state NMR, and molecular modelling.

    PubMed

    Filip, Xenia; Borodi, Gheorghe; Filip, Claudiu

    2011-10-28

    A solid state structural investigation of ethoxzolamide is performed on microcrystalline powder by using a multi-technique approach that combines X-ray powder diffraction (XRPD) data analysis based on direct space methods with information from (13)C((15)N) solid-state Nuclear Magnetic Resonance (SS-NMR) and molecular modeling. Quantum chemical computations of the crystal were employed for geometry optimization and chemical shift calculations based on the Gauge Including Projector Augmented-Wave (GIPAW) method, whereas a systematic search in the conformational space was performed on the isolated molecule using a molecular mechanics (MM) approach. The applied methodology proved useful for: (i) removing ambiguities in the XRPD crystal structure determination process and further refining the derived structure solutions, and (ii) getting important insights into the relationship between the complex network of non-covalent interactions and the induced supra-molecular architectures/crystal packing patterns. It was found that ethoxzolamide provides an ideal case study for testing the accuracy with which this methodology allows to distinguish between various structural features emerging from the analysis of the powder diffraction data. PMID:21931906

  14. Kilowatt-level near-diffraction-limited and linear-polarized Ytterbium-Raman hybrid nonlinear amplifier based on polarization selection loss mechanism.

    PubMed

    Ma, Pengfei; Zhang, Hanwei; Huang, Long; Wang, Xiaolin; Zhou, Pu; Liu, Zejin

    2015-10-01

    Ytterbium-Raman cascaded oscillators with linearly polarized output are designed and achieved based on polarization selection loss (PSL) mechanism for the first time. The 1120 nm laser cavity is designed with fully non polarization-maintained (NPM) fiber Bragg gratings (FBGs) and NPM active fiber while the 1080 nm laser cavity is designed based on polarization-maintained (PM) FBGs and PM active fiber. By using PSL mechanism in 1080 nm cavity, even with fully NPM 1120 nm cavity, both linear-polarized 1120 nm and 1080 nm lasers are achieved in the output port of the cascaded oscillators. Based on the new designed cascaded seeds, a high power polarization-maintained Yb-Raman hybrid nonlinear amplifier is established for further power scaling of the 1120 nm laser. In the nonlinear amplifier, only 21-meter-long active fiber and 1.5-meter-long passive fiber is used for power transferring from 1080 nm to 1120 nm. Output power of 1181 W is achieved at central wavelength of 1120 nm with the M(2) factor of <1.2 and polarization-extinction ratio (PER) of 18.2 dB. As far as we known, the output power of this all fiber format is the highest one in 1120 nm with linear polarization. This type of high power Yb-Raman nonlinear amplifier design with linear polarization can be further extended to Yb-Raman amplifying the wavelength range of 1100-1200 nm. PMID:26480163

  15. Integrated Diffractive Optics for Surface Ion Traps

    NASA Astrophysics Data System (ADS)

    Streed, Erik; Ghadimi, Moji; Blums, Valdis; Norton, Benjamin; Connor, Paul; Amini, Jason; Volin, Curtis; Lobino, Mirko; Kielpinski, David

    2016-05-01

    Photonic interconnects are a bottleneck to achieving large-scale trapped ion quantum computing. We have modified a Georgia Tech Research Institute microwave chip trap by using e-beam lithography to write reflective diffractive collimating optics (80 μm x 127 μm, f=58.6 μm, λ=369.5nm) on the center electrode. The optics have an NA of 0.55 x 0.73, capturing 13.2% of the solid angle. To evaluate the optics 174Yb+ was loaded by isotope selective photo-ionization from a thermal oven and then shuttled to imaging sites. Near diffraction limited sub-wavelength ion images were obtained with an observed spot sized FWHM of 338 nm x 268 nm vs. a diffraction limit of 336 nm x 257 nm. The total photon collection efficiency was measured to be 5.2+/-1.2%. Coupling into a single mode fiber of up to 2.0+/-0.6% was observed, limited by mismatch in the coupling optics. Image mode quality indicates coupling up to 4% may be possible. Funding from Australian Research Council and IARPA.

  16. Diffractive interference optical analyzer (DiOPTER)

    NASA Astrophysics Data System (ADS)

    Sasikumar, Harish; Prasad, Vishnu; Pal, Parama; Varma, Manoj M.

    2016-03-01

    This report demonstrates a method for high-resolution refractometric measurements using, what we have termed as, a Diffractive Interference Optical Analyzer (DiOpter). The setup consists of a laser, polarizer, a transparent diffraction grating and Si-photodetectors. The sensor is based on the differential response of diffracted orders to bulk refractive index changes. In these setups, the differential read-out of the diffracted orders suppresses signal drifts and enables time-resolved determination of refractive index changes in the sample cell. A remarkable feature of this device is that under appropriate conditions, the measurement sensitivity of the sensor can be enhanced by more than two orders of magnitude due to interference between multiply reflected diffracted orders. A noise-equivalent limit of detection (LoD) of 6x10-7 RIU was achieved in glass. This work focuses on devices with integrated sample well, made on low-cost PDMS. As the detection methodology is experimentally straightforward, it can be used across a wide array of applications, ranging from detecting changes in surface adsorbates via binding reactions to estimating refractive index (and hence concentration) variations in bulk samples. An exciting prospect of this technique is the potential integration of this device to smartphones using a simple interface based on transmission mode configuration. In a transmission configuration, we were able to achieve an LoD of 4x10-4 RIU which is sufficient to explore several applications in food quality testing and related fields. We are envisioning the future of this platform as a personal handheld optical analyzer for applications ranging from environmental sensing to healthcare and quality testing of food products.

  17. Computation of highly off-axis diffracted fields using the band-limited angular spectrum method with suppressed Gibbs related artifacts.

    PubMed

    Falaggis, Konstantinos; Kozacki, Tomasz; Kujawinska, Malgorzata

    2013-05-10

    The angular spectrum (AS) method is a popular solution to the Helmholtz equation without the use of approximations. Modified band-limited AS methods are of particular interest for the cases of high-off-axis and large distance propagation problems, because conventional AS methods are impractical due to requirements regarding memory and computational effort. However, these techniques make use of rectangular-shaped filters that introduce ringing artifacts in the calculated field that are related to the Gibbs phenomenon. This work proposes AS algorithms based on a smooth band-limiting filter for accurate field computation as well as techniques that evaluate only nonzero components of the field. This enables accurate field calculations with an acceptable level of computational effort that cannot be offered by current AS methods reported in the scientific literature. PMID:23669842

  18. Design and experiment of 4H-SiC JBS diodes achieving a near-theoretical breakdown voltage with non-uniform floating limiting rings terminal

    NASA Astrophysics Data System (ADS)

    Yuan, Hao; Song, Qingwen; Tang, Xiaoyan; Zhang, Yimeng; Zhang, Yimen; Zhang, Yuming

    2016-09-01

    In this paper, a 4H-SiC Junction Barrier Schottky diode (JBS) with non-uniform floating limiting rings (FLRs) has been investigated and fabricated using n type 4H-SiC epitaxial layer with thickness of 31 μm and doping concentration of 3.3 × 1015 cm-3. According to the simulated results, the key parameters of a FLRs design to achieve a high voltage are the minimum space between two adjacent doped rings, spacing growth step and number of rings. The experimental results also show a great agreement with simulated results. Meanwhile, a near-ideal breakdown voltage of 3.7 kV was achieved, which yield around 95% of the parallel-plane breakdown voltage. The forward characteristics show that the fabricated JBS diodes have a forward current density of 210 A/cm2 at 3 V and a specific on-resistance (Rsp-on) of 7.58 mΩ cm2. Different FLRs parameters have no effect on the forward device performance.

  19. Polychromatic diffraction contrast tomography

    SciTech Connect

    King, A.; Reischig, P.; Adrien, J.; Peetermans, S.; Ludwig, W.

    2014-11-15

    This tutorial review introduces the use of polychromatic radiation for 3D grain mapping using X-ray diffraction contrast tomography. The objective is to produce a 3D map of the grain shapes and orientations within a bulk, millimeter-sized polycrystalline sample. The use of polychromatic radiation enables the standard synchrotron X-ray technique to be applied in a wider range of contexts: 1) Using laboratory X-ray sources allows a much wider application of the diffraction contrast tomography technique. 2) Neutron sources allow large samples, or samples containing high Z elements to be studied. 3) Applied to synchrotron sources, smaller samples may be treated, or faster measurements may be possible. Challenges and particularities in the data acquisition and processing, and the limitations of the different variants, are discussed. - Highlights: • We present a tutorial review of polychromatic diffraction contrast tomography techniques. • The use of polychromatic radiation allows the standard synchrotron DCT technique to be extended to a range of other sources. • The characteristics and limitations of all variants of the techniques are derived, discussed and compared. • Examples using laboratory X-ray and cold neutron radiation are presented. • Suggestions for the future development of these techniques are presented.

  20. Diffraction before destruction

    PubMed Central

    Chapman, Henry N.; Caleman, Carl; Timneanu, Nicusor

    2014-01-01

    X-ray free-electron lasers have opened up the possibility of structure determination of protein crystals at room temperature, free of radiation damage. The femtosecond-duration pulses of these sources enable diffraction signals to be collected from samples at doses of 1000 MGy or higher. The sample is vaporized by the intense pulse, but not before the scattering that gives rise to the diffraction pattern takes place. Consequently, only a single flash diffraction pattern can be recorded from a crystal, giving rise to the method of serial crystallography where tens of thousands of patterns are collected from individual crystals that flow across the beam and the patterns are indexed and aggregated into a set of structure factors. The high-dose tolerance and the many-crystal averaging approach allow data to be collected from much smaller crystals than have been examined at synchrotron radiation facilities, even from radiation-sensitive samples. Here, we review the interaction of intense femtosecond X-ray pulses with materials and discuss the implications for structure determination. We identify various dose regimes and conclude that the strongest achievable signals for a given sample are attained at the highest possible dose rates, from highest possible pulse intensities. PMID:24914146

  1. Femtosecond single-electron diffraction

    PubMed Central

    Lahme, S.; Kealhofer, C.; Krausz, F.; Baum, P.

    2014-01-01

    Ultrafast electron diffraction allows the tracking of atomic motion in real time, but space charge effects within dense electron packets are a problem for temporal resolution. Here, we report on time-resolved pump-probe diffraction using femtosecond single-electron pulses that are free from intra-pulse Coulomb interactions over the entire trajectory from the source to the detector. Sufficient average electron current is achieved at repetition rates of hundreds of kHz. Thermal load on the sample is avoided by minimizing the pump-probe area and by maximizing heat diffusion. Time-resolved diffraction from fibrous graphite polycrystals reveals coherent acoustic phonons in a nanometer-thick grain ensemble with a signal-to-noise level comparable to conventional multi-electron experiments. These results demonstrate the feasibility of pump-probe diffraction in the single-electron regime, where simulations indicate compressibility of the pulses down to few-femtosecond and attosecond duration. PMID:26798778

  2. Microarcsecond relative astrometry from the ground with a diffractive pupil

    SciTech Connect

    Ammons, S M; Bendek, E; Guyon, O

    2011-09-08

    The practical use of astrometry to detect exoplanets via the reflex motion of the parent star depends critically on the elimination of systematic floors in imaging systems. In the diffractive pupil technique proposed for space-based detection of exo-earths, extended diffraction spikes generated by a dotted primary mirror are referenced against a wide-field grid of background stars to calibrate changing optical distortion and achieve microarcsecond astrometric precision on bright targets (Guyon et al. 2010). We describe applications of this concept to ground-based uncrowded astrometry using a diffractive, monopupil telescope and a wide-field camera to image as many as {approx}4000 background reference stars. Final relative astrometric precision is limited by differential tip/tilt jitter caused by high altitude layers of turbulence. A diffractive 3-meter telescope is capable of reaching {approx}35 {micro}as relative astrometric error per coordinate perpendicular to the zenith vector in three hours on a bright target star (I < 10) in fields of moderate stellar density ({approx}40 stars arcmin{sup -2} with I < 23). Smaller diffractive apertures (D < 1 m) can achieve 100-200 {micro}as performance with the same stellar density and exposure time and a large telescope (6.5-10 m) could achieve as low as 10 {micro}as, nearly an order of magnitude better than current space-based facilities. The diffractive pupil enables the use of larger fields of view through calibration of changing optical distortion as well as brighter target stars (V < 6) by preventing star saturation. Permitting the sky to naturally roll to average signals over many thousands of pixels can mitigate the effects of detector imperfections.

  3. Dichroic Coherent Diffractive Imaging

    NASA Astrophysics Data System (ADS)

    Tripathi, Ashish

    Understanding electronic structure at nanometer resolution is crucial to understanding physics such as phase separation and emergent behavior in correlated electron materials. Nondestructive probes which have the ability to see beyond surfaces on nanometer length and sub-picosecond time scales can greatly enhance our understanding of these systems and will impact development of future technologies, such as magnetic storage. Polarized x-rays are an appealing choice of probe due to their penetrating power, elemental and magnetic specificity, and high spatial resolution. The resolution of traditional x-ray microscopy is limited by the nanometer precision required to fabricate x-ray optics. In this thesis, a novel approach to lensless imaging of an extended magnetic nanostructure is presented. We demonstrate this approach by imaging ferrimagnetic "maze" domains in a Gd/Fe multilayer with perpendicular anisotropy. A series of dichroic coherent diffraction patterns, ptychographically recorded, are numerically inverted using non-convex and non-linear optimization theory, and we follow the magnetic domain configuration evolution through part of its magnetization hysteresis loop by applying an external magnetic field. Unlike holographic methods, it does not require a reference wave or precision optics, and so is a far simpler experiment. In addition, it enables the imaging of samples with arbitrarily large spatial dimensions, at a spatial resolution limited solely by the coherent x-ray flux and wavelength. It can readily be extended to other non-magnetic systems that exhibit circular or linear dichroism. This approach is scalable to imaging with diffraction-limited resolution, a prospect rapidly becoming a reality in view of the new generation of phenomenally brilliant x-ray sources.

  4. Lensless reflective point diffraction interferometer.

    PubMed

    Zhu, Wenhua; Chen, Lei; Zheng, Donghui; Yang, Ying; Han, Zhigang; Li, Jinpeng

    2016-07-01

    A lensless reflective point diffraction interferometer (LRPDI) is proposed for dynamic wavefront measurement. The point diffraction interferometer is integrated on a small substrate with properly designed thin film, which is used for generating the interferogram with high carrier frequency at a CCD target. By lensless imaging, the complex amplitude at the CCD target can be propagated to the conjugated plane of the exit pupil of an incident wavefront, which not only avoids the edge diffraction in the interferogram, but also eliminates systematic error. The accuracy of LRPDI is demonstrated by simulation and experiment, and a precision better than 1/150 wavelength is achieved. The new design with lensless imaging processing is suitable for dynamic wavefront measurement. PMID:27409204

  5. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, Gary E.

    1996-01-01

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

  6. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, G.E.

    1996-08-29

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of {lambda}/1000 where {lambda} is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about {lambda}/50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms. 8 figs.

  7. Tolerance analysis of multilayer diffractive optics based on polychromatic integral diffraction efficiency.

    PubMed

    Mao, Shan; Cui, Qingfeng; Piao, Mingxu

    2015-11-10

    Multilayer diffractive optical elements (MLDOEs) can achieve high diffraction efficiency for broadband wavelength. Polychromatic integral diffraction efficiency (PIDE) is the key concern for evaluating diffraction efficiency over the waveband. The modulation transfer function of a hybrid refractive-diffractive optical system is directly affected by the PIDE. The relationship between PIDE and continuous manufacturing errors for microstructure heights and periodic widths of MLDOEs is studied theoretically in this paper, and an example of MLDOEs is discussed in the visible waveband. The analysis results can be used for manufacturing error control in microstructure heights and periodic widths. PMID:26560782

  8. Microarcsecond Astrometry with MCAO Using a Diffractive Mask

    NASA Astrophysics Data System (ADS)

    Ammons, S. Mark; Bendek, Eduardo A.; Guyon, Olivier; Macintosh, Bruce; Savransky, Dmitry

    2014-04-01

    We present a new ground-based technique to detect or follow-up long-period, potentially habitable exoplanets via precise relative astrometry of host stars using Multi-Conjugate Adaptive Optics (MCAO) on 8 meter telescopes equipped with diffractive masks. MCAO improves relative astrometry both by cancellation of high-altitude atmospheric layers, which induce dynamic focal-plane distortions, and the improvement of centroiding precision with sharper PSFs. However, mass determination of habitable exoplanets requires multi-year reference grid stability of ~1-10 μas or nanometer-level stability on the long-term average of out-of-pupil phase errors, which is difficult to achieve with MCAO (e.g., Meyer et al. 2011). The diffractive pupil technique calibrates dynamic distortion via extended diffraction spikes generated by a dotted primary mirror, which are referenced against a grid of background stars (Guyon et al. 2012). The diffractive grid provides three benefits to relative astrometry: (1) increased dynamic range, permitting observation of V < 10 stars without saturation; (2) calibration of dynamic distortion; and (3) a spectrum of the target star, which can be used to calibrate the magnitude of differential atmospheric refraction to the microarcsecond level. A diffractive 8-meter telescope with diffraction-limited MCAO in K-band reaches < 3-5 μas relative astrometric error per coordinate perpendicular to the zenith vector in one hour on a bright target star in fields of moderate stellar density (~10-40 stars arcmin-2). We present preliminary on-sky results of a test of the diffractive mask on the Nickel telescope at Lick Observatory.

  9. X-Ray Diffraction.

    ERIC Educational Resources Information Center

    Smith, D. K.; Smith, K. L.

    1980-01-01

    Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)

  10. Calculation of the diffraction efficiency on concave gratings based on Fresnel-Kirchhoff's diffraction formula.

    PubMed

    Huang, Yuanshen; Li, Ting; Xu, Banglian; Hong, Ruijin; Tao, Chunxian; Ling, Jinzhong; Li, Baicheng; Zhang, Dawei; Ni, Zhengji; Zhuang, Songlin

    2013-02-10

    Fraunhofer diffraction formula cannot be applied to calculate the diffraction wave energy distribution of concave gratings like plane gratings because their grooves are distributed on a concave spherical surface. In this paper, a method based on the Kirchhoff diffraction theory is proposed to calculate the diffraction efficiency on concave gratings by considering the curvature of the whole concave spherical surface. According to this approach, each groove surface is divided into several limited small planes, on which the Kirchhoff diffraction field distribution is calculated, and then the diffraction field of whole concave grating can be obtained by superimposition. Formulas to calculate the diffraction efficiency of Rowland-type and flat-field concave gratings are deduced from practical applications. Experimental results showed strong agreement with theoretical computations. With the proposed method, light energy can be optimized to the expected diffraction wave range while implementing aberration-corrected design of concave gratings, particularly for the concave blazed gratings. PMID:23400074

  11. High-resolution projection image reconstruction of thick objects by hard x-ray diffraction microscopy

    SciTech Connect

    Takahashi, Yukio; Nishino, Yoshinori; Tsutsumi, Ryosuke; Zettsu, Nobuyuki; Matsubara, Eiichiro; Yamauchi, Kazuto; Ishikawa, Tetsuya

    2010-12-01

    Hard x-ray diffraction microscopy enables us to observe thick objects at high spatial resolution. The resolution of this method is limited, in principle, by only the x-ray wavelength and the largest scattering angle recorded. As the resolution approaches the wavelength, the thickness effect of objects plays a significant role in x-ray diffraction microscopy. In this paper, we report high-resolution hard x-ray diffraction microscopy for thick objects. We used highly focused coherent x rays with a wavelength of {approx}0.1 nm as an incident beam and measured the diffraction patterns of a {approx}150-nm-thick silver nanocube at the scattering angle of {approx}3 deg. We observed a characteristic contrast of the coherent diffraction pattern due to only the thickness effect and collected the diffraction patterns at nine incident angles so as to obtain information on a cross section of Fourier space. We reconstructed a pure projection image by the iterative phasing method from the patched diffraction pattern. The edge resolution of the reconstructed image was {approx}2 nm, which was the highest resolution so far achieved by x-ray microscopy. The present study provides us with a method for quantitatively observing thick samples at high resolution by hard x-ray diffraction microscopy.

  12. Diffractive optics fabricated by direct write methods with an electron beam

    NASA Technical Reports Server (NTRS)

    Kress, Bernard; Zaleta, David; Daschner, Walter; Urquhart, Kris; Stein, Robert; Lee, Sing H.

    1993-01-01

    State-of-the-art diffractive optics are fabricated using e-beam lithography and dry etching techniques to achieve multilevel phase elements with very high diffraction efficiencies. One of the major challenges encountered in fabricating diffractive optics is the small feature size (e.g. for diffractive lenses with small f-number). It is not only the e-beam system which dictates the feature size limitations, but also the alignment systems (mask aligner) and the materials (e-beam and photo resists). In order to allow diffractive optics to be used in new optoelectronic systems, it is necessary not only to fabricate elements with small feature sizes but also to do so in an economical fashion. Since price of a multilevel diffractive optical element is closely related to the e-beam writing time and the number of etching steps, we need to decrease the writing time and etching steps without affecting the quality of the element. To do this one has to utilize the full potentials of the e-beam writing system. In this paper, we will present three diffractive optics fabrication techniques which will reduce the number of process steps, the writing time, and the overall fabrication time for multilevel phase diffractive optics.

  13. Distributed etched diffraction grating demultiplexer

    NASA Astrophysics Data System (ADS)

    Jafari, Amir

    This doctoral thesis studies the concept of a distributed etched diffraction grating (DEDG) and presents a methodology to engineer the spectral response of the device. The design which incorporates a distributed Bragg reflector (DBR) at the facets of a conventional etched diffraction grating demultiplexer promises for a superior performance in multiple aspects. Where in a conventional etched diffraction grating, smooth vertical deep etched walls are required in order to realize a low insertion loss device; in the DEDG such requirement is significantly mitigated. Deep etched walls are replaced with shallowly etched diffraction grating facets followed by a DBR structure and as a result devices with significantly lower insertion loss are achievable. The feasibility of the application of DEDG as a wavelength demultiplexer was demonstrated through fabrication and characterization of a prototype device. The proof of concept device was fabricated using the state of the art deep UV optical lithography and reactive ion etching in a nano-photonic silicon-on-insulator (SOI) material platform. The fabricated device was then characterized in the lab. Furthermore, incorporation of the DBR structure at the facets of the conventional etched diffraction grating decouples the reflection and diffraction functionalities, rendering the DEDG suitable for spectral response engineering. According to the application, the output spectral response of the device can be tailored through careful design and optimization of the incorporated DBR. In this thesis, through numerical simulations we have shown that functionalities such as polarization independent performance and at top insertion loss envelop are viable. A methodology to engineer the spectral response of the DEDG is discussed in details.

  14. Testing the limits of Paleozoic chronostratigraphic correlation via high-resolution (13Ccarb) biochemostratigraphy across the Llandovery–Wenlock (Silurian) boundary: Is a unified Phanerozoic time scale achievable?

    USGS Publications Warehouse

    Cramer, Bradley D.; Loydell, David K.; Samtleben, Christian; Munnecke, Axel; Kaljo, Dimitri; Mannik, Peep; Martma, Tonu; Jeppsson, Lennart; Kleffner, Mark A.; Barrick, James E.; Johnson, Craig A.; Emsbo, Poul; Joachimski, Michael M.; Bickert, Torsten; Saltzman, Matthew R.

    2010-01-01

    The resolution and fidelity of global chronostratigraphic correlation are direct functions of the time period under consideration. By virtue of deep-ocean cores and astrochronology, the Cenozoic and Mesozoic time scales carry error bars of a few thousand years (k.y.) to a few hundred k.y. In contrast, most of the Paleozoic time scale carries error bars of plus or minus a few million years (m.y.), and chronostratigraphic control better than ??1 m.y. is considered "high resolution." The general lack of Paleozoic abyssal sediments and paucity of orbitally tuned Paleozoic data series combined with the relative incompleteness of the Paleozoic stratigraphic record have proven historically to be such an obstacle to intercontinental chronostratigraphic correlation that resolving the Paleozoic time scale to the level achieved during the Mesozoic and Cenozoic was viewed as impractical, impossible, or both. Here, we utilize integrated graptolite, conodont, and carbonate carbon isotope (??13Ccarb) data from three paleocontinents (Baltica, Avalonia, and Laurentia) to demonstrate chronostratigraphic control for upper Llando very through middle Wenlock (Telychian-Sheinwoodian, ~436-426 Ma) strata with a resolution of a few hundred k.y. The interval surrounding the base of the Wenlock Series can now be correlated globally with precision approaching 100 k.y., but some intervals (e.g., uppermost Telychian and upper Shein-woodian) are either yet to be studied in sufficient detail or do not show sufficient biologic speciation and/or extinction or carbon isotopic features to delineate such small time slices. Although producing such resolution during the Paleozoic presents an array of challenges unique to the era, we have begun to demonstrate that erecting a Paleozoic time scale comparable to that of younger eras is achievable. ?? 2010 Geological Society of America.

  15. Chromatic confocal microscopy using staircase diffractive surface.

    PubMed

    Rayer, Mathieu; Mansfield, Daniel

    2014-08-10

    A chromatic confocal microscope (CCM) is a high-dynamic-range noncontact distance measurement sensor; it is based on a hyperchromatic lens. The vast majority of commercial CCMs use refractive-based chromatic dispersion to chromatically code the optical axis. This approach significantly limits the range of applications and performance of the CCM. In order to be a suitable alternative to a laser triangulation gauge and laser encoder, the performance of the CCM must be improved. In this paper, it is shown how hybrid aspheric diffractive (HAD) lenses can bring the CCM to its full potential by increasing the dynamic range by a factor of 2 and the resolution by a factor of 5 while passively athermizing and increasing the light throughput efficiency of the optical head [M. Rayer, U.S. patent 1122052.2 (2011)]. The only commercially suitable manufacturing process is single-point diamond turning. However, the optical power carried by the diffractive side of a hybrid aspheric diffractive lens is limited by the manufacturing process. A theoretical study of manufacturing losses has revealed that the HAD configuration with the highest diffraction efficiency is for a staircase diffractive surface (SDS). SDS lenses have the potential to reduce light losses associated with manufacturing limits by a factor of 5 without increasing surface roughness, allowing scalar diffraction-limited optical design with a diffractive element. PMID:25320920

  16. Limited femoral navigation versus conventional intramedullary femoral jig based instrumentation for achieving optimal restoration of mechanical axis post total knee arthroplasty: a prospective comparative study of 200 knees.

    PubMed

    Shah, Nilen A; Patil, Hitendra G; Dhawale, Amol S; Khedkar, Bipin M

    2015-04-01

    A prospective comparative study was conducted to compare the mechanical axis post total knee arthroplasty (TKA) between two groups: In the first group of 100 knees (ASM group) Articular Surface Mounted navigation system was used to guide the distal femoral cut. In the second group of 100 knees (JIG group) conventional intramedullary femoral jig was used. The postoperative mechanical axis of the leg was within 3° of neutral alignment in 90% of the TKA in the ASM group (mean 178.12°) as compared to 74% in the JIG group (mean 177.02°). This difference was statistically significant (P<0.05). The data presented show that the use of limited femoral navigation leads to more accurate restoration of mechanical axis alignment when compared to conventional intramedullary femoral jigs. PMID:25466168

  17. Detonation diffraction through different geometries

    NASA Astrophysics Data System (ADS)

    Sorin, Rémy; Zitoun, Ratiba; Khasainov, Boris; Desbordes, Daniel

    2009-04-01

    We performed the study of the diffraction of a self-sustained detonation from a cylindrical tube (of inner diameter d) through different geometric configurations in order to characterise the transmission processes and to quantify the transmission criteria to the reception chamber. For the diffraction from a tube to the open space the transmission criteria is expressed by d c = k c · λ (with λ the detonation cell size and k c depending on the mixture and on the operture configuration, classically 13 for alkane mixtures with oxygen). The studied geometries are: (a) a sharp increase of diameter ( D/ d > 1) with and without a central obstacle in the diffracting section, (b) a conical divergent with a central obstacle in the diffracting section and (c) an inversed intermediate one end closed tube insuring a double reflection before a final diffraction between the initiator tube and the reception chamber. The results for case A show that the reinitiation process depends on the ratio d/ λ. For ratios below k c the re-ignition takes place at the receptor tube wall and at a fixed distance from the step, i.e. closely after the diffracted shock reflection shows a Mach stem configuration. For ratios below a limit ratio k lim (which depends on D/ d) the re-ignition distance increases with the decrease of d/λ. For both case A and B the introduction of a central obstacle (of blockage ratio BR = 0.5) at the exit of the initiator tube decreases the critical transmission ratio k c by 50%. The results in configuration C show that the re-ignition process depends both on d/ λ and the geometric conditions. Optimal configuration is found that provides the transmission through the two successive reflections (from d = 26 mm to D ch = 200 mm) at as small d/ λ as 2.2 whatever the intermediate diameter D is. This configuration provides a significant improvement in the detonation transmission conditions.

  18. Feasibility studies for high pressure neutron powder diffraction experiments

    SciTech Connect

    Von Dreele, R.B. ); Parise, J. )

    1990-01-01

    We recently performed two neutron powder diffraction experiments on very small samples on the High Intensity Powder Diffractometer (HIPD). These were done to determine the feasibility of performing in situ high pressure/high temperature neutron diffraction experiments on HIPD at pressures which would exceed the previous limit of {approximately}50 kbar achievable in a neutron diffraction experiment. The first experiment consisted of examining the product from a high pressure preparation done at Stony Brook. The sample, which had been prepared at 65 kbar and 1000{degree}C, consisted of a small platinum capsule filled with CaGeO{sub 3} perovskite. The weights of the capsule included 225 mg of platinum and 49 mg of the germanate. A diffraction experiment taking {approximately}8.6 hrs at a LANSCE proton beam current of {approximately}53 {mu}A gave peaks of good intensity from both Pt and CaGeO{sub 3}; we could begin to see them after only 20 min of beam time. The second experiment was to test the possibility of diffraction from a high pressure apparatus. We placed in the HIPD sample position the central assembly from a 100 kbar octahedral press. Four tungsten carbide anvils and a copper block previously pressed to 65 kbar were held in an aluminum frame. The sample consisted of a small bit of nickel foil (175 mg) placed in a 3 mm hole in the copper block. The active sample volume is defined by the gap between the anvils and the length of the sample. A small portion of the copper block is also seen in this arrangement. This is viewed at 90{degree} 2{Theta} through a similar gap between the anvils by 4 1/2 in. {times} 12 in. {sup 3}He counter tubes. This arrangement simulates the operating conditions of a high pressure run at 100 kbar and takes advantage of the fixed instrument geometry possible in time-of-flight neutron diffraction experiments.

  19. Structured illumination diffraction phase microscopy for broadband, sub-diffraction resolution, quantitative phase imaging

    PubMed Central

    Chowdhury, Shwetadwip; Izatt, Joseph A.

    2015-01-01

    Structured illumination microscopy (SIM) is an established technique that allows sub-diffraction resolution imaging by heterodyning high sample frequencies into the system’s passband via structured illumination. However, until now, SIM has been typically used to achieve sub-diffraction resolution for intensity-based imaging. Here, we present a novel optical setup that uses structured illumination with a broadband-light source to obtain noise-reduced, sub-diffraction resolution, quantitative-phase (QPM) imaging of cells. We compare this with a previous work for sub-diffraction QPM imaging via SIM that used a laser source, and was thus still corrupted by coherent noise. PMID:24562266

  20. Effect of recording condition on the diffraction efficiency of magnetic hologram with magnetic garnet films

    NASA Astrophysics Data System (ADS)

    Nakamura, Yuichi; Takagi, Hiroyuki; Lim, Pang Boey; Inoue, Mitsuteru

    2014-09-01

    A holographic memory has been attracting attention as recording media with high recording density and high data transfer rate. We have studied the magnetic garnets as a rewritable and long life media for magnetic holography. However, since the signal intensity of reconstructed image was relatively low, the effects of recording conditions on the diffraction efficiency of magnetic hologram were investigated with experiments and the numerical simulation using COMSOL multi-physics. The diffraction efficiency tends to decrease as increasing the spatial frequency, and the use of short pulse laser with the pulse width of 50 ps was found to be effective to achieve high diffraction efficiency. This suggests that the formation of clear magnetic fringe similar to interference pattern can be obtained by the use of short pulse laser since undesirable heat diffusion during radiation does not occur. On the other hand, the diffraction efficiency increased as increasing the film thickness up to 3.1 μm but was saturated in the garnet film thicker than 3.1 μm in the case of spatial frequency of 1500 line pair/mm. The numerical simulation showed that the effective depth of magnetic fringe was limited about 1.8 μm irrespective of the garnet film thickness because the fringes were connected by thermal diffusion near the surface of the film, and the effective depth is limited due to this connection of the magnetic fringe. Avoiding this fringe connection, much higher diffraction efficiency will be achieved.

  1. Effect of recording condition on the diffraction efficiency of magnetic hologram with magnetic garnet films

    SciTech Connect

    Nakamura, Yuichi Takagi, Hiroyuki; Lim, Pang Boey; Inoue, Mitsuteru

    2014-09-14

    A holographic memory has been attracting attention as recording media with high recording density and high data transfer rate. We have studied the magnetic garnets as a rewritable and long life media for magnetic holography. However, since the signal intensity of reconstructed image was relatively low, the effects of recording conditions on the diffraction efficiency of magnetic hologram were investigated with experiments and the numerical simulation using COMSOL multi-physics. The diffraction efficiency tends to decrease as increasing the spatial frequency, and the use of short pulse laser with the pulse width of 50 ps was found to be effective to achieve high diffraction efficiency. This suggests that the formation of clear magnetic fringe similar to interference pattern can be obtained by the use of short pulse laser since undesirable heat diffusion during radiation does not occur. On the other hand, the diffraction efficiency increased as increasing the film thickness up to 3.1 μm but was saturated in the garnet film thicker than 3.1 μm in the case of spatial frequency of 1500 line pair/mm. The numerical simulation showed that the effective depth of magnetic fringe was limited about 1.8 μm irrespective of the garnet film thickness because the fringes were connected by thermal diffusion near the surface of the film, and the effective depth is limited due to this connection of the magnetic fringe. Avoiding this fringe connection, much higher diffraction efficiency will be achieved.

  2. Speciation Analysis of Arsenic by Selective Hydride Generation-Cryotrapping-Atomic Fluorescence Spectrometry with Flame-in-Gas-Shield Atomizer: Achieving Extremely Low Detection Limits with Inexpensive Instrumentation

    PubMed Central

    2015-01-01

    This work describes the method of a selective hydride generation-cryotrapping (HG-CT) coupled to an extremely sensitive but simple in-house assembled and designed atomic fluorescence spectrometry (AFS) instrument for determination of toxicologically important As species. Here, an advanced flame-in-gas-shield atomizer (FIGS) was interfaced to HG-CT and its performance was compared to a standard miniature diffusion flame (MDF) atomizer. A significant improvement both in sensitivity and baseline noise was found that was reflected in improved (4 times) limits of detection (LODs). The yielded LODs with the FIGS atomizer were 0.44, 0.74, 0.15, 0.17 and 0.67 ng L–1 for arsenite, total inorganic, mono-, dimethylated As and trimethylarsine oxide, respectively. Moreover, the sensitivities with FIGS and MDF were equal for all As species, allowing for the possibility of single species standardization with arsenate standard for accurate quantification of all other As species. The accuracy of HG-CT-AFS with FIGS was verified by speciation analysis in two samples of bottled drinking water and certified reference materials, NRC CASS-5 (nearshore seawater) and SLRS-5 (river water) that contain traces of methylated As species. As speciation was in agreement with results previously reported and sums of all quantified species corresponded with the certified total As. The feasibility of HG-CT-AFS with FIGS was also demonstrated by the speciation analysis in microsamples of exfoliated bladder epithelial cells isolated from human urine. The results for the sums of trivalent and pentavalent As species corresponded well with the reference results obtained by HG-CT-ICPMS (inductively coupled plasma mass spectrometry). PMID:25300934

  3. Speciation analysis of arsenic by selective hydride generation-cryotrapping-atomic fluorescence spectrometry with flame-in-gas-shield atomizer: achieving extremely low detection limits with inexpensive instrumentation.

    PubMed

    Musil, Stanislav; Matoušek, Tomáš; Currier, Jenna M; Stýblo, Miroslav; Dědina, Jiří

    2014-10-21

    This work describes the method of a selective hydride generation-cryotrapping (HG-CT) coupled to an extremely sensitive but simple in-house assembled and designed atomic fluorescence spectrometry (AFS) instrument for determination of toxicologically important As species. Here, an advanced flame-in-gas-shield atomizer (FIGS) was interfaced to HG-CT and its performance was compared to a standard miniature diffusion flame (MDF) atomizer. A significant improvement both in sensitivity and baseline noise was found that was reflected in improved (4 times) limits of detection (LODs). The yielded LODs with the FIGS atomizer were 0.44, 0.74, 0.15, 0.17 and 0.67 ng L(-1) for arsenite, total inorganic, mono-, dimethylated As and trimethylarsine oxide, respectively. Moreover, the sensitivities with FIGS and MDF were equal for all As species, allowing for the possibility of single species standardization with arsenate standard for accurate quantification of all other As species. The accuracy of HG-CT-AFS with FIGS was verified by speciation analysis in two samples of bottled drinking water and certified reference materials, NRC CASS-5 (nearshore seawater) and SLRS-5 (river water) that contain traces of methylated As species. As speciation was in agreement with results previously reported and sums of all quantified species corresponded with the certified total As. The feasibility of HG-CT-AFS with FIGS was also demonstrated by the speciation analysis in microsamples of exfoliated bladder epithelial cells isolated from human urine. The results for the sums of trivalent and pentavalent As species corresponded well with the reference results obtained by HG-CT-ICPMS (inductively coupled plasma mass spectrometry). PMID:25300934

  4. Using multiple diffractive optical elements in infrared lens design

    NASA Astrophysics Data System (ADS)

    Sinclair, R. Lawrence; High, Martin; Strnad, Vladimir

    1999-07-01

    Many IR lenses include Diffractive Optical Elements (DOEs) which have been incorporated to reduce the lens complexity and/or the tolerance sensitivity. In many cases the diffractive surface includes an asphere to achieve further aberration correction. For complex lens systems such as IR multi-FOV and IR zoom lenses there is a strong motivation to use multiple diffractive optical elements. This paper reviews the performance impact and productivity advantages of using multiple diffractive optical elements in an IR lens.

  5. Diffraction by cold atoms

    NASA Astrophysics Data System (ADS)

    Strauch, F.; Gomer, V.; Schadwinkel, H.; Ueberholz, B.; Haubrich, D.; Meschede, D.

    1998-01-01

    We have observed diffraction of a laser probe beam by a trapped sample of cold atoms. The effect is only visible in the vicinity of a resonance line. The observed diffraction pattern arises from interference of the incident and scattered light wave, allowing reconstruction of geometric properties of the trapped sample from the holographic record.

  6. Diffraction Results from CDF

    SciTech Connect

    Goulianos, Konstantin

    2012-04-01

    We present final results by the CDF II collaboration on diffractive W and Z production, report on the status of ongoing analyses on diffractive dijet production and on rapidity gaps between jets, and briefly summarize results obtained on exclusive production pointing to their relevance to calibrating theoretical models used to predict exclusive Higgs-boson production at the LHC.

  7. Phononic crystal diffraction gratings

    NASA Astrophysics Data System (ADS)

    Moiseyenko, Rayisa P.; Herbison, Sarah; Declercq, Nico F.; Laude, Vincent

    2012-02-01

    When a phononic crystal is interrogated by an external source of acoustic waves, there is necessarily a phenomenon of diffraction occurring on the external enclosing surfaces. Indeed, these external surfaces are periodic and the resulting acoustic diffraction grating has a periodicity that depends on the orientation of the phononic crystal. This work presents a combined experimental and theoretical study on the diffraction of bulk ultrasonic waves on the external surfaces of a 2D phononic crystal that consists of a triangular lattice of steel rods in a water matrix. The results of transmission experiments are compared with theoretical band structures obtained with the finite-element method. Angular spectrograms (showing frequency as a function of angle) determined from diffraction experiments are then compared with finite-element simulations of diffraction occurring on the surfaces of the crystal. The experimental results show that the diffraction that occurs on its external surfaces is highly frequency-dependent and has a definite relation with the Bloch modes of the phononic crystal. In particular, a strong influence of the presence of bandgaps and deaf bands on the diffraction efficiency is found. This observation opens perspectives for the design of efficient phononic crystal diffraction gratings.

  8. Subdiffraction-limited focusing lens.

    PubMed

    Davis, J A; Cottrell, D M; Maley, C A; Crivello, M R

    1994-07-01

    We describe techniques for making a diffractive optical element that produces a subdiffraction-limited spot size. We provide experimental verification, using a diffraction optical element that is constructed on a magneto-optic spatial light modulator. PMID:20935762

  9. Stretchable diffraction gratings for spectrometry

    NASA Astrophysics Data System (ADS)

    Simonov, Aleksey N.; Grabarnik, Semen; Vdovin, Gleb

    2007-07-01

    We have investigated the possibility of using transparent stretchable diffraction gratings for spectrometric applications. The gratings were fabricated by replication of a triangular-groove master into a transparent viscoelastic. The sample length, and hence the spatial period, can be reversibly changed by mechanical stretching. When used in a monochromator with two slits, the stretchable grating permits scanning the spectral components over the output slit, converting the monochromator into a scanning spectrometer. The spectral resolution of such a spectrometer was found to be limited mainly by the wave-front aberrations due to the grating deformation. A model relating the deformation-induced aberrations in different diffraction orders is presented. In the experiments, a 12-mm long viscoelastic grating with a spatial frequency of 600 line pairs/mm provided a full-width at half-maximum resolution of up to ~1.2 nm in the 580-680 nm spectral range when slowly stretched by a micrometer screw and ~3 nm when repeatedly stretched by a voice coil at 15 Hz. Comparison of aberrations in transmitted and diffracted beams measured by a Shack- Hartmann wave-front sensor showed that astigmatisms caused by stretch-dependent wedge deformation are the main factors limiting the resolution of the viscoelastic-grating-based spectrometer.

  10. Precision lens molding of asphero diffractive surfaces in chalcogenide materials

    NASA Astrophysics Data System (ADS)

    Nelson, J.; Scordato, M.; Schwertz, K.; Bagwell, J.

    2015-10-01

    Finished lens molding, and the similar process of precision lens molding, have long been practiced for high volume, accurate replication of optical surfaces on oxide glass. The physics surrounding these processes are well understood, and the processes are capable of producing high quality optics with great fidelity. However, several limitations exist due to properties inherent with oxide glasses. Tooling materials that can withstand the severe environmental conditions of oxide glass molding cannot easily be machined to produce complex geometries such as diffractive surfaces, lens arrays, and off axis features. Current machining technologies coupled with a limited selection of tool materials greatly limits the type of structures that can be molded into the finished optic. Tooling for chalcogenide glasses are not bound by these restrictions since the molding temperatures required are much lower than for oxide glasses. Innovations in tooling materials and manufacturing techniques have enabled the production of complex geometries to optical quality specifications and have demonstrated the viability of creating tools for molding diffractive surfaces, off axis features, datums, and arrays. Applications for optics having these features are found in automotive, defense, security, medical, and industrial domains. This paper will discuss results achieved in the study of various molding techniques for the formation of positive diffractive features on a concave spherical surface molded from As2Se3 chalcogenide glass. Examples and results of molding with tools having CTE match with the glass and non CTE match will be reviewed. The formation of stress within the glass during molding will be discussed, and methods of stress management will also be demonstrated and discussed. Results of process development methods and production of good diffractive surfaces will be shown.

  11. High numerical aperture tabletop soft x-ray diffraction microscopy with 70-nm resolution

    PubMed Central

    Sandberg, Richard L.; Song, Changyong; Wachulak, Przemyslaw W.; Raymondson, Daisy A.; Paul, Ariel; Amirbekian, Bagrat; Lee, Edwin; Sakdinawat, Anne E.; La-O-Vorakiat, Chan; Marconi, Mario C.; Menoni, Carmen S.; Murnane, Margaret M.; Rocca, Jorge J.; Kapteyn, Henry C.; Miao, Jianwei

    2008-01-01

    Light microscopy has greatly advanced our understanding of nature. The achievable resolution, however, is limited by optical wavelengths to ≈200 nm. By using imaging and labeling technologies, resolutions beyond the diffraction limit can be achieved for specialized specimens with techniques such as near-field scanning optical microscopy, stimulated emission depletion microscopy, and photoactivated localization microscopy. Here, we report a versatile soft x-ray diffraction microscope with 70- to 90-nm resolution by using two different tabletop coherent soft x-ray sources—a soft x-ray laser and a high-harmonic source. We also use field curvature correction that allows high numerical aperture imaging and near-diffraction-limited resolution of 1.5λ. A tabletop soft x-ray diffraction microscope should find broad applications in biology, nanoscience, and materials science because of its simple optical design, high resolution, large depth of field, 3D imaging capability, scalability to shorter wavelengths, and ultrafast temporal resolution. PMID:18162534

  12. dxtbx: the diffraction experiment toolbox.

    PubMed

    Parkhurst, James M; Brewster, Aaron S; Fuentes-Montero, Luis; Waterman, David G; Hattne, Johan; Ashton, Alun W; Echols, Nathaniel; Evans, Gwyndaf; Sauter, Nicholas K; Winter, Graeme

    2014-08-01

    Data formats for recording X-ray diffraction data continue to evolve rapidly to accommodate new detector technologies developed in response to more intense light sources. Processing the data from single-crystal X-ray diffraction experiments therefore requires the ability to read, and correctly interpret, image data and metadata from a variety of instruments employing different experimental representations. Tools that have previously been developed to address this problem have been limited either by a lack of extensibility or by inconsistent treatment of image metadata. The dxtbx software package provides a consistent interface to both image data and experimental models, while supporting a completely generic user-extensible approach to reading the data files. The library is written in a mixture of C++ and Python and is distributed as part of the cctbx under an open-source licence at http://cctbx.sourceforge.net. PMID:25242914

  13. Calculating incoherent diffraction MTF

    NASA Astrophysics Data System (ADS)

    Friedman, Melvin; Vizgaitis, Jay

    2008-04-01

    The incoherent diffraction MTF plays an increasingly important role in the range performance of imaging systems as the wavelength increases and the optical aperture decreases. Accordingly, all NVESD imager models have equations that describe the incoherent diffraction MTF of a circular entrance pupil. NVThermIP, a program which models thermal imager range performance, has built in equations which analytically model the incoherent diffraction MTF of a circular entrance pupil and has a capability to input a table that describes the MTF of other apertures. These can be calculated using CODE V, which can numerically calculate the incoherent diffraction MTF in the vertical or horizontal direction for an arbitrary aperture. However, we are not aware of any program that takes as input a description of the entrance pupil and analytically outputs equations that describe the incoherent diffraction MTF. This work explores the effectiveness of Mathematica to analytically and numerically calculate the incoherent diffraction MTF for an arbitrary aperture. In this work, Mathematica is used to analytically and numerically calculate the incoherent diffraction MTF for a variety of apertures and the results are compared with CODE V calculations.

  14. Diffraction techniques in structural biology.

    PubMed

    Egli, Martin

    2010-06-01

    A detailed understanding of chemical and biological function and the mechanisms underlying the molecular activities ultimately requires atomic-resolution structural data. Diffraction-based techniques such as single-crystal X-ray crystallography, electron microscopy, and neutron diffraction are well established and they have paved the road to the stunning successes of modern-day structural biology. The major advances achieved in the last 20 years in all aspects of structural research, including sample preparation, crystallization, the construction of synchrotron and spallation sources, phasing approaches, and high-speed computing and visualization, now provide specialists and nonspecialists alike with a steady flow of molecular images of unprecedented detail. The present unit combines a general overview of diffraction methods with a detailed description of the process of a single-crystal X-ray structure determination experiment, from chemical synthesis or expression to phasing and refinement, analysis, and quality control. For novices it may serve as a stepping-stone to more in-depth treatises of the individual topics. Readers relying on structural information for interpreting functional data may find it a useful consumer guide. PMID:20517991

  15. Diffraction Techniques in Structural Biology.

    PubMed

    Egli, Martin

    2016-01-01

    A detailed understanding of chemical and biological function and the mechanisms underlying the molecular activities ultimately requires atomic-resolution structural data. Diffraction-based techniques such as single-crystal X-ray crystallography, electron microscopy, and neutron diffraction are well established and they have paved the road to the stunning successes of modern-day structural biology. The major advances achieved in the last twenty years in all aspects of structural research, including sample preparation, crystallization, the construction of synchrotron and spallation sources, phasing approaches, and high-speed computing and visualization, now provide specialists and nonspecialists alike with a steady flow of molecular images of unprecedented detail. The present unit combines a general overview of diffraction methods with a detailed description of the process of a single-crystal X-ray structure determination experiment, from chemical synthesis or expression to phasing and refinement, analysis, and quality control. For novices it may serve as a stepping-stone to more in-depth treatises of the individual topics. Readers relying on structural information for interpreting functional data may find it a useful consumer guide. © 2016 by John Wiley & Sons, Inc. PMID:27248784

  16. Diffraction Techniques in Structural Biology

    PubMed Central

    Egli, Martin

    2010-01-01

    A detailed understanding of chemical and biological function and the mechanisms underlying the activities ultimately requires atomic-resolution structural data. Diffraction-based techniques such as single-crystal X-ray crystallography, electron microscopy and neutron diffraction are well established and have paved the road to the stunning successes of modern-day structural biology. The major advances achieved in the last 20 years in all aspects of structural research, including sample preparation, crystallization, the construction of synchrotron and spallation sources, phasing approaches and high-speed computing and visualization, now provide specialists and non-specialists alike with a steady flow of molecular images of unprecedented detail. The present chapter combines a general overview of diffraction methods with a step-by-step description of the process of a single-crystal X-ray structure determination experiment, from chemical synthesis or expression to phasing and refinement, analysis and quality control. For novices it may serve as a stepping-stone to more in-depth treatises of the individual topics. Readers relying on structural information for interpreting functional data may find it a useful consumer guide. PMID:20517991

  17. New diffractive results from the Tevatron

    SciTech Connect

    Gallinaro, Michele; /Rockefeller U.

    2005-05-01

    Experimental results in diffractive processes are summarized and a few notable characteristics described in terms of Quantum Chromodynamics. Exclusive dijet production is used to establish a benchmark for future experiments in the quest for diffractive Higgs production at the Large Hadron Collider. Using new data from the Tevatron and dedicated diffractive triggers, no excess over a smooth falling distribution for exclusive dijet events could be found. Stringent upper limits on the exclusive dijet production cross section are presented. The quark/gluon composition of dijet final states is used to provide additional hints on exclusive dijet production.

  18. Diffraction pattern of gratings with erosion

    NASA Astrophysics Data System (ADS)

    Olivares-Pérez, Arturo; Fuentes-Tapia, Israel

    2015-03-01

    We present a theoretical study of amplitude diffraction gratings using computer simulating, which consists of a random sampling of points on the image grating to determine the points to be plotted and the points to remove, to simulate erosion in amplitude on the grating. We show their behavior in the diffraction patterns and the induced noise by limiting the number of points that representing the image of the eroded gratings and their symmetry.

  19. Hard diffraction at CDF

    SciTech Connect

    Melese, P.L.; CDF Collaboration

    1996-07-01

    We present new evidence for events with a rapidity gap between jets in {bar p}-p collisions at {radical}s = 1.8 TeV based on data collected by triggering the Collider Detector at Fermilab on two high transverse momentum forward jets and results of a search for diffractive W{+-} and dijet production where diffraction is tagged by the rapidity gap technique. We also present the results of a search for diffractive dijets using data collected by triggering on a very forward particle in the recently installed roman-pot detectors. The dijet events exhibit additional diffractive characteristics such as rapidity gaps and boosted center of mass system, however the recoil antiproton measured in the roman-pots is in a regime in which the non- pomeron contribution is significant.

  20. Reflective diffraction grating

    DOEpatents

    Lamartine, Bruce C.

    2003-06-24

    Reflective diffraction grating. A focused ion beam (FIB) micromilling apparatus is used to store color images in a durable medium by milling away portions of the surface of the medium to produce a reflective diffraction grating with blazed pits. The images are retrieved by exposing the surface of the grating to polychromatic light from a particular incident bearing and observing the light reflected by the surface from specified reception bearing.

  1. Optical diffraction tomography: accuracy of an off-axis reconstruction

    NASA Astrophysics Data System (ADS)

    Kostencka, Julianna; Kozacki, Tomasz

    2014-05-01

    Optical diffraction tomography is an increasingly popular method that allows for reconstruction of three-dimensional refractive index distribution of semi-transparent samples using multiple measurements of an optical field transmitted through the sample for various illumination directions. The process of assembly of the angular measurements is usually performed with one of two methods: filtered backprojection (FBPJ) or filtered backpropagation (FBPP) tomographic reconstruction algorithm. The former approach, although conceptually very simple, provides an accurate reconstruction for the object regions located close to the plane of focus. However, since FBPJ ignores diffraction, its use for spatially extended structures is arguable. According to the theory of scattering, more precise restoration of a 3D structure shall be achieved with the FBPP algorithm, which unlike the former approach incorporates diffraction. It is believed that with this method one is allowed to obtain a high accuracy reconstruction in a large measurement volume exceeding depth of focus of an imaging system. However, some studies have suggested that a considerable improvement of the FBPP results can be achieved with prior propagation of the transmitted fields back to the centre of the object. This, supposedly, enables reduction of errors due to approximated diffraction formulas used in FBPP. In our view this finding casts doubt on quality of the FBPP reconstruction in the regions far from the rotation axis. The objective of this paper is to investigate limitation of the FBPP algorithm in terms of an off-axis reconstruction and compare its performance with the FBPJ approach. Moreover, in this work we propose some modifications to the FBPP algorithm that allow for more precise restoration of a sample structure in off-axis locations. The research is based on extensive numerical simulations supported with wave-propagation method.

  2. Powder Diffraction: By Decades

    NASA Astrophysics Data System (ADS)

    David, William I. F.

    This introductory chapter reviews the first 100 years of powder diffraction, decade by decade, from the earliest X-ray powder diffraction measurements of the crystal structure of graphite through to the diversity and complexity of twenty-first century powder diffraction. Carbon features as an illustrative example throughout the discussion of these ten decades from graphite and the disorder of carbon black through to lonsdaleite, the elusive hexagonal polymorph of diamond, and C60, the most symmetrical of molecules. Electronics and computing have played a leading role in the development of powder diffraction, particularly over the past 60 years, and the Moore's Law decade-by-decade rise in computing power is clear in the increasing complexity of powder diffraction experiments and material systems that can be studied. The chapter concludes with a final discussion of decades - the four decades of length-scale from the ångstrom to the micron that not only represent the domain of powder diffraction but are also the distances that will dominate twenty-first century science and technology.

  3. Diffractive properties of imaginary-part photonic crystal slab

    PubMed Central

    2012-01-01

    The diffraction spectra of imaginary-part photonic crystal (IPPC) slabs are analyzed using the scattering-matrix method. By investigating the thickness dependence of the diffraction, we find a remarkable red shift of central wavelength of the diffraction spectrum, which obviously distinguishes from the phenomenon of spectral hole. We observe that diffraction efficiency can be enhanced more than 20-fold by optimizing the geometry parameters. These imply that the diffraction spectra of the IPPC slab can be controlled at will and used to guide the design to achieve useful nanoscale devices. PMID:22720871

  4. A Diffraction-limited Survey for Direct Detection of Halpha Emitting/Accreting ExtraSolar Planets with the 6.5m Magellan Telescope and the MagAO Visible AO system

    NASA Astrophysics Data System (ADS)

    Close, Laird

    steady diet of hydrogen gas. Such planets should then be quite bright in Halpha accretion emission. The key point is that: instead of a steep drop off in the luminosity of the planet’s atmosphere, the accretion luminosity of these planets will just linearly decrease with decreasing mass. At an accretion rate=6e-10 Msun/yr we find low mass (~1 Mjup) accreting gap planets are much (50-1000x) brighter (for 0-3.4 mag of Halpha extinction) in Halpha than at H band. PROOF-OF_CONCEPT: A 3 hour MagAO observation at Halpha of a transitional disk in April 2013 was made. The resulting deep diffraction-limited images discovered (at 10.5 sigma) an Halpha source that was 295% above the continuum just 0.083” from the star (edge of the inner 10 AU disk gap). We also detected (at 5 sigma) an excellent (though much fainter) ~1 Mjup mass Halpha planet candidate located auspiciously at the outer edge (145 AU) of the gap. If confirmed by our “second epoch” follow-up as common proper motion then this would be the lowest mass (~1 Mjup) planet ever imaged. SURVEY: Scaling off of this exciting success we propose to deeply image (120 min) all 14 nearby (D<250pc), bright (R<11 mag) , not edge-on (i<80 deg) , young (~5 Myr) transitional disks with MagAO simultaneously at Halpha and L’. In addition, we will use BrGamma instead of Halpha for 8 additional fainter (111 Mjup in mass, we integrate across our target list and find that, in the worst case of minimal masses (1+/-0.5 Mjup), and 3.4 mag extinction, at least seven ~1 Mjup planets should be discovered by this survey --meeting all three of our science goals above.

  5. Multipath analysis diffraction calculations

    NASA Technical Reports Server (NTRS)

    Statham, Richard B.

    1996-01-01

    This report describes extensions of the Kirchhoff diffraction equation to higher edge terms and discusses their suitability to model diffraction multipath effects of a small satellite structure. When receiving signals, at a satellite, from the Global Positioning System (GPS), reflected signals from the satellite structure result in multipath errors in the determination of the satellite position. Multipath error can be caused by diffraction of the reflected signals and a method of calculating this diffraction is required when using a facet model of the satellite. Several aspects of the Kirchhoff equation are discussed and numerical examples, in the near and far fields, are shown. The vector form of the extended Kirchhoff equation, by adding the Larmor-Tedone and Kottler edge terms, is given as a mathematical model in an appendix. The Kirchhoff equation was investigated as being easily implemented and of good accuracy in the basic form, especially in phase determination. The basic Kirchhoff can be extended for higher accuracy if desired. A brief discussion of the method of moments and the geometric theory of diffraction is included, but seems to offer no clear advantage in implementation over the Kirchhoff for facet models.

  6. Diffractive Optical Analysis for Refractive Index Sensing using Transparent Phase Gratings

    PubMed Central

    Kumawat, Nityanand; Pal, Parama; Varma, Manoj

    2015-01-01

    We report the implementation of a micro-patterned, glass-based photonic sensing element that is capable of label-free biosensing. The diffractive optical analyzer is based on the differential response of diffracted orders to bulk as well as surface refractive index changes. The differential read-out suppresses signal drifts and enables time-resolved determination of refractive index changes in the sample cell. A remarkable feature of this device is that under appropriate conditions, the measurement sensitivity of the sensor can be enhanced by more than two orders of magnitude due to interference between multiply reflected diffracted orders. A noise-equivalent limit of detection (LoD) of 6 × 10−7 was achieved with this technique with scope for further improvement. PMID:26578408

  7. The impact of novel 3D diffraction optics development

    NASA Astrophysics Data System (ADS)

    Firsov, Alexander; Brzhezinskaya, Maria; Loechel, Heike; Siewert, Frank; Erko, Alexei

    2013-05-01

    Dedicated diffractive VUV- and X-ray optical elements are essential for future developments in synchrotron instrumentation and methods like e.g. time-resolved spectroscopy. The quality of optical components like gratings or diffractive focusing elements matters directly to the results achievable. On the other hand the availability of such optical components is very limited at present. In this contribution we report on the development of new methods of time-resolved x-ray spectroscopy based on novel 3D diffractive optical elements (DOE) with a unique combination of properties. Such optical elements are of highest interest for application in modern synchrotron facilities like Free Electron Lasers (FELs) as well as for laboratory facilities with high harmonic generators (HHG). The project includes theoretical work as well as the development of a dedicated technology, including metrology, to manufacture such type of optics for applications in atomic, molecular and condensed matter physics. The here discussed type of optics was successfully implemented for soft-X-ray-application at the femto-second-slicing beamline at BESSY II storage ring of the Helmholtz Zentrum Berlin. DOE are expected to be important components in beamlines at upcoming new high brilliance X-ray sources such as FELs. The application of DOE`s allows to reduce the number of optical elements in a beamline. Thus allow to provide the highest possible transmission and flux as well as preserving the unique properties of FEĹs, like wave-front and coherence.

  8. Diffraction radiation generators

    NASA Astrophysics Data System (ADS)

    Shestopalov, Viktor P.; Vertii, Aleksei A.; Ermak, Gennadii P.; Skrynnik, Boris K.; Khlopov, Grigorii I.; Tsvyk, Aleksei I.

    Research in the field of diffraction radiation generators (DRG) conducted at the Radio Physics and electronics Institute of the Ukranian Academy of Sciences over the past 25 years is reviewed. The effect of diffraction radiation is analyzed in detail, and various operating regimes of DRGs are discussed. The discussion then focuses on the principal requirements for the design of packaged DRGs and their principal parameters. Finally, applications of DRGs in various fields of science and technology are reviewed, including such applications as DRG spectroscopy, diagnostics of plasma, biological specimens, and vibration, and DRG radar systems.

  9. Eyeglass. 1. Very large aperture diffractive telescopes.

    PubMed

    Hyde, R A

    1999-07-01

    The Eyeglass is a very large aperture (25-100-m) space telescope consisting of two distinct spacecraft, separated in space by several kilometers. A diffractive lens provides the telescope s large aperture, and a separate, much smaller, space telescope serves as its mobile eyepiece. Use of a transmissive diffractive lens solves two basic problems associated with very large aperture space telescopes; it is inherently launchable (lightweight, packagable, and deployable) it and virtually eliminates the traditional, very tight surface shape tolerances faced by reflecting apertures. The potential drawback to use of a diffractive primary (very narrow spectral bandwidth) is eliminated by corrective optics in the telescope s eyepiece; the Eyeglass can provide diffraction-limited imaging with either single-band (Deltalambda/lambda approximately 0.1), multiband, or continuous spectral coverage. PMID:18323902

  10. Diffraction gratings for optical sensing

    NASA Astrophysics Data System (ADS)

    Lu, Patrick P.

    The following document summarizes a journey through the world of diffraction gratings, covering topics such as their history, fabrication, metrology, and uses in some of the most precise scientific experiments ever proposed. Though diffraction gratings have long been used for spectroscopy and pulse compression, it was not until recently that researchers have explored their ability to split and recombine single-frequency CW laser sources for high-precision interferometry. Gravitational-wave detection, one of the most challenging sensing applications to date, is being investigated by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Laser Interferometer Space Antenna (LISA) projects. Future generations of LIGO and LISA detectors may incorporate gratings as key optical components. This thesis describes the ways gratings can improve interferometer performance by simplifying thermal management and discusses the essential challenges that must be overcome before they can be adopted. The use of gratings requires new interferometer geometries. We show cases where these can be implemented simply and compactly. Gravitational-wave interferometry imposes many requirements on grating components. Using improved metrology methods, we demonstrate that large dielectric gratings with uniformly high efficiency can be fabricated and validated. In particular, we measure the diffraction efficiency of two 20-cm-scale gratings over their entire apertures. The values taken from across their surfaces collectively had means and standard deviations of mu = 99.293% and sigma = 0.164%, and mu =99.084% and sigma =0.079%. We also present simplified models of thermal distortions in gratings, and show them to be in good agreement with measurements conducted by a wavefront sensor. Special focus is given to experimental demonstrations that have achieved highly precise measurements of translational and rotational motion, also known as displacement and angular sensing. For the former

  11. Non-diffractive computational ghost imaging.

    PubMed

    Phillips, D B; He, Ruiqing; Chen, Qian; Gibson, G M; Padgett, M J

    2016-06-27

    Computational ghost imaging (CGI) enables an image to be recorded using a single-pixel detector. The image can be reconstructed from correlations between the scene and a series of known projected intensity patterns. In this work we investigate the performance of CGI using pseudo non-diffracting (ND) speckle patterns. We demonstrate an extended depth-of-field that is ∼ 2-3 times greater than that achievable with conventional speckle, when only computing each intensity pattern to a single depth. In addition, the average speckle grain size of ND speckle is reduced by a factor of ∼ 1.5 relative to conventional speckle, which enhances the lateral Rayleigh-limit resolving power of our reconstructed images. However, the point-spread function (PSF) of our imaging system takes the form of a Bessel beam, which manifests itself as long-range correlations between speckle grains in the projected patterns. We discuss the trade-off between enhancement of the depth-of-field and the lateral resolution when using ND speckle, at the expense of a reduction in image contrast. Our work demonstrates that the tailoring of lateral and axial correlations in projected intensity patterns permits PSF engineering in CGI. PMID:27410575

  12. DIFFRACTION FROM MODEL CRYSTALS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although calculating X-ray diffraction patterns from atomic coordinates of a crystal structure is a widely available capability, calculation from non-periodic arrays of atoms has not been widely applied to cellulose. Non-periodic arrays result from modeling studies that, even though started with at...

  13. Calculating cellulose diffraction patterns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although powder diffraction of cellulose is a common experiment, the patterns are not widely understood. The theory is mathematical, there are numerous different crystal forms, and the conventions are not standardized. Experience with IR spectroscopy is not directly transferable. An awful error, tha...

  14. Diffractive hard scattering

    SciTech Connect

    Berger, E.L.; Collins, J.C.; Soper, D.E.; Sterman, G.

    1986-03-01

    I discuss events in high energy hadron collisions that contain a hard scattering, in the sense that very heavy quarks or high P/sub T/ jets are produced, yet are diffractive, in the sense that one of the incident hadrons is scattered with only a small energy loss. 8 refs.

  15. On-sky Tests of High-Precision Astrometry Using a Diffractive Mask

    NASA Astrophysics Data System (ADS)

    Ammons, Stephen; Bendek, E.; Macintosh, B.; Guyon, O.

    2013-01-01

    We present a new ground-based technique to detect or follow-up long-period, potentially habitable exoplanets via precise relative astrometry of host stars using Multi-Conjugate Adaptive Optics (MCAO) on 8 meter telescopes equipped with diffractive masks. MCAO improves relative astrometry both by cancellation of high-altitude atmospheric layers, which induce dynamic focal-plane distortions, and the improvement of centroiding precision with sharper PSFs. However, mass determination of habitable exoplanets requires multi-year reference grid stability of ~1-10 uas or nanometer-level stability on the long-term average of out-of-pupil phase errors, which is difficult to achieve with MCAO (e.g., Meyer et al. 2011). The diffractive pupil technique calibrates dynamic distortion via extended diffraction spikes generated by a dotted primary mirror, which are referenced against a grid of background stars (Guyon et al. 2012). We show that the diffractive pupil improves MCAO's long-term astrometric stability to the microarcsecond level. The diffractive grid provides four benefits to relative astrometry: (1) increased dynamic range, permitting observation of V < 10 stars without saturation; (2) calibration of dynamic distortion; and (3) a spectrum of the target star, which can be used to calibrate the magnitude of differential atmospheric refraction to the microarcsecond level. A diffractive 8-meter telescope with diffraction-limited MCAO in K-band reaches < 3-5 µas relative astrometric error per coordinate in one hour on a bright target star in fields of moderate stellar density 10-40 stars arcmin-2). We present results of an on-sky test of the diffractive pupil on the Nickel 1-meter telescope at Lick Observatory, obtained in Fall 2012.

  16. Diffraction efficiency sensitivity to oblique incident angle for multilayer diffractive optical elements.

    PubMed

    Yang, Hongfang; Xue, Changxi; Li, Chuang; Wang, Ju; Zhang, Ran

    2016-09-01

    The relationship between diffraction efficiency of multilayer diffractive optical elements (MLDOEs) and arbitrary incident angle was numerically analyzed with the effective area method. The method is based on the shield effect between two elements of MLDOEs; a generalized diffraction efficiency formulation was obtained in a wide range of tilt angles, which overcame the limitations of scalar diffraction theory when the period width of MLDOEs is taken into account. A detailed comparison of the proposed effective area method with the scalar diffraction theory is numerically presented for MLDOEs. The validity of the proposed method is verified by comparison with the rigorous electromagnetic analysis method, especially the finite-difference time-domain method. The analysis results show that the shield effect augments with the increase of the incident angles; the effect of incident angles on MLDOEs with finite period widths is more noticeable than that with large period widths. PMID:27607291

  17. Coherent diffractive imaging of single layer microspheres

    SciTech Connect

    Dinh, Khuong Ba Le, Hoang Vu; Van Vuong, Cuong; Hannaford, Peter; Van Dao, Lap; Ong, Adabelle X. P.; Henderson, Clare A.; Smith, Trevor A.

    2015-04-28

    We report the extreme ultraviolet (XUV) coherent diffractive imaging of silica/polymer micro-particle samples illuminated by a table-top high harmonic generation source at the wavelength of 30 nm. We achieve images constructed from diffraction patterns acquired with 13 μm × 13 μm samples comprising a sparse monolayer of spherical silica and polymer micro-particles. Successful reconstructed image of an aperiodic sample using this HHG source will open the path to the realization of a compact soft x-ray microscope to investigate other complex absorbing samples.

  18. Tomographic observation of transparent objects under coherent illumination and reconstruction by filtered backprojection and Fourier diffraction theorem

    NASA Astrophysics Data System (ADS)

    Vertu, Stanislas; Yamada, Ichiro; Delaunay, Jean-Jacques; Haeberlé, Olivier

    2008-02-01

    We report first results in the comparison between filtered backprojection reconstruction and Fourier diffraction theorem reconstruction of transparent spherical samples using a diffractive optical microtomography instrument. A brightfield transmission microscope was modified to form a Mach-Zehnder interferometer that was used to generate phase-shifted holograms recorded in image plane. Transparent objects mixed with an index matching medium were inserted into a microcapillary and holograms of these objects were taken under different view angles by rotating the microcapillary. Precise rotation of the microcapillary was accomplished by clipping the microcapillary in a precisely machined V-groove, a system that when combined with software correction of the object centre achieved a precision of object positioning on the order of a micrometer. Tomography of weakly diffracting objects was performed and the observed objects were reconstructed by two methods namely, the filtered backprojection method and the Fourier diffraction method. In the filtered backprojection reconstruction, the 3-D distribution of the refractive index was computed from the tomography of the object phase. In the Fourier diffraction reconstruction, the 3-D distribution of the scattering potential was computed by 3-D Fourier transform of the mapping of the object spatial frequencies. It was confirmed that the Fourier diffraction reconstruction based on the first order Born approximation is limited to small phase changes. In contrast, the backprojection performed well on large phase changes, but dramatically failed to reconstruct diffractive objects by generating reconstruction line artifacts that spread from the diffractive object to other nearby objects. Weakly diffractive polymer beads exhibiting small phase changes were correctly reconstructed by both methods, the Fourier diffraction method giving sharper edges than the filtered backprojection method.

  19. Macromolecular diffractive imaging using imperfect crystals.

    PubMed

    Ayyer, Kartik; Yefanov, Oleksandr M; Oberthür, Dominik; Roy-Chowdhury, Shatabdi; Galli, Lorenzo; Mariani, Valerio; Basu, Shibom; Coe, Jesse; Conrad, Chelsie E; Fromme, Raimund; Schaffer, Alexander; Dörner, Katerina; James, Daniel; Kupitz, Christopher; Metz, Markus; Nelson, Garrett; Xavier, Paulraj Lourdu; Beyerlein, Kenneth R; Schmidt, Marius; Sarrou, Iosifina; Spence, John C H; Weierstall, Uwe; White, Thomas A; Yang, Jay-How; Zhao, Yun; Liang, Mengning; Aquila, Andrew; Hunter, Mark S; Robinson, Joseph S; Koglin, Jason E; Boutet, Sébastien; Fromme, Petra; Barty, Anton; Chapman, Henry N

    2016-02-11

    The three-dimensional structures of macromolecules and their complexes are mainly elucidated by X-ray protein crystallography. A major limitation of this method is access to high-quality crystals, which is necessary to ensure X-ray diffraction extends to sufficiently large scattering angles and hence yields information of sufficiently high resolution with which to solve the crystal structure. The observation that crystals with reduced unit-cell volumes and tighter macromolecular packing often produce higher-resolution Bragg peaks suggests that crystallographic resolution for some macromolecules may be limited not by their heterogeneity, but by a deviation of strict positional ordering of the crystalline lattice. Such displacements of molecules from the ideal lattice give rise to a continuous diffraction pattern that is equal to the incoherent sum of diffraction from rigid individual molecular complexes aligned along several discrete crystallographic orientations and that, consequently, contains more information than Bragg peaks alone. Although such continuous diffraction patterns have long been observed--and are of interest as a source of information about the dynamics of proteins--they have not been used for structure determination. Here we show for crystals of the integral membrane protein complex photosystem II that lattice disorder increases the information content and the resolution of the diffraction pattern well beyond the 4.5-ångström limit of measurable Bragg peaks, which allows us to phase the pattern directly. Using the molecular envelope conventionally determined at 4.5 ångströms as a constraint, we obtain a static image of the photosystem II dimer at a resolution of 3.5 ångströms. This result shows that continuous diffraction can be used to overcome what have long been supposed to be the resolution limits of macromolecular crystallography, using a method that exploits commonly encountered imperfect crystals and enables model-free phasing. PMID

  20. Macromolecular diffractive imaging using imperfect crystals

    PubMed Central

    Ayyer, Kartik; Yefanov, Oleksandr; Oberthür, Dominik; Roy-Chowdhury, Shatabdi; Galli, Lorenzo; Mariani, Valerio; Basu, Shibom; Coe, Jesse; Conrad, Chelsie E.; Fromme, Raimund; Schaffer, Alexander; Dörner, Katerina; James, Daniel; Kupitz, Christopher; Metz, Markus; Nelson, Garrett; Lourdu Xavier, Paulraj; Beyerlein, Kenneth R.; Schmidt, Marius; Sarrou, Iosifina; Spence, John C. H.; Weierstall, Uwe; White, Thomas A.; Yang, Jay-How; Zhao, Yun; Liang, Mengning; Aquila, Andrew; Hunter, Mark S.; Robinson, Joseph S.; Koglin, Jason E.; Boutet, Sébastien; Fromme, Petra; Barty, Anton; Chapman, Henry N.

    2016-01-01

    The three-dimensional structures of macromolecules and their complexes are predominantly elucidated by X-ray protein crystallography. A major limitation is access to high-quality crystals, to ensure X-ray diffraction extends to sufficiently large scattering angles and hence yields sufficiently high-resolution information that the crystal structure can be solved. The observation that crystals with shrunken unit-cell volumes and tighter macromolecular packing often produce higher-resolution Bragg peaks1,2 hints that crystallographic resolution for some macromolecules may be limited not by their heterogeneity but rather by a deviation of strict positional ordering of the crystalline lattice. Such displacements of molecules from the ideal lattice give rise to a continuous diffraction pattern, equal to the incoherent sum of diffraction from rigid single molecular complexes aligned along several discrete crystallographic orientations and hence with an increased information content3. Although such continuous diffraction patterns have long been observed—and are of interest as a source of information about the dynamics of proteins4 —they have not been used for structure determination. Here we show for crystals of the integral membrane protein complex photosystem II that lattice disorder increases the information content and the resolution of the diffraction pattern well beyond the 4.5 Å limit of measurable Bragg peaks, which allows us to directly phase5 the pattern. With the molecular envelope conventionally determined at 4.5 Å as a constraint, we then obtain a static image of the photosystem II dimer at 3.5 Å resolution. This result shows that continuous diffraction can be used to overcome long-supposed resolution limits of macromolecular crystallography, with a method that puts great value in commonly encountered imperfect crystals and opens up the possibility for model-free phasing6,7. PMID:26863980

  1. Macromolecular diffractive imaging using imperfect crystals

    NASA Astrophysics Data System (ADS)

    Ayyer, Kartik; Yefanov, Oleksandr M.; Oberthür, Dominik; Roy-Chowdhury, Shatabdi; Galli, Lorenzo; Mariani, Valerio; Basu, Shibom; Coe, Jesse; Conrad, Chelsie E.; Fromme, Raimund; Schaffer, Alexander; Dörner, Katerina; James, Daniel; Kupitz, Christopher; Metz, Markus; Nelson, Garrett; Xavier, Paulraj Lourdu; Beyerlein, Kenneth R.; Schmidt, Marius; Sarrou, Iosifina; Spence, John C. H.; Weierstall, Uwe; White, Thomas A.; Yang, Jay-How; Zhao, Yun; Liang, Mengning; Aquila, Andrew; Hunter, Mark S.; Robinson, Joseph S.; Koglin, Jason E.; Boutet, Sébastien; Fromme, Petra; Barty, Anton; Chapman, Henry N.

    2016-02-01

    The three-dimensional structures of macromolecules and their complexes are mainly elucidated by X-ray protein crystallography. A major limitation of this method is access to high-quality crystals, which is necessary to ensure X-ray diffraction extends to sufficiently large scattering angles and hence yields information of sufficiently high resolution with which to solve the crystal structure. The observation that crystals with reduced unit-cell volumes and tighter macromolecular packing often produce higher-resolution Bragg peaks suggests that crystallographic resolution for some macromolecules may be limited not by their heterogeneity, but by a deviation of strict positional ordering of the crystalline lattice. Such displacements of molecules from the ideal lattice give rise to a continuous diffraction pattern that is equal to the incoherent sum of diffraction from rigid individual molecular complexes aligned along several discrete crystallographic orientations and that, consequently, contains more information than Bragg peaks alone. Although such continuous diffraction patterns have long been observed—and are of interest as a source of information about the dynamics of proteins—they have not been used for structure determination. Here we show for crystals of the integral membrane protein complex photosystem II that lattice disorder increases the information content and the resolution of the diffraction pattern well beyond the 4.5-ångström limit of measurable Bragg peaks, which allows us to phase the pattern directly. Using the molecular envelope conventionally determined at 4.5 ångströms as a constraint, we obtain a static image of the photosystem II dimer at a resolution of 3.5 ångströms. This result shows that continuous diffraction can be used to overcome what have long been supposed to be the resolution limits of macromolecular crystallography, using a method that exploits commonly encountered imperfect crystals and enables model-free phasing.

  2. Spatial resolution limits for synchrotron-based spectromicroscopy in the mid- and near-infrared

    SciTech Connect

    Levenson, Erika; Lerch, Philippe; Martin, Michael C.

    2008-01-12

    Spatial resolution tests were performed on beamline 1.4.4 at the Advanced Light Source in Berkeley, CA, USA, a third-generation synchrotron light source. This beamline couples the high-brightness synchrotron source to a Thermo-Electron Continumum XL infrared microscope. Two types of resolution tests were performed in both the mid-IR and near-IR. The results are compared with a diffraction-limited spot size theory. At shorter near-IR wavelengths the experimental results begin to deviate from diffraction-limited so a combined diffraction-limit and electron-beam-source-size model is employed. This description shows how the physical electron beam size of the synchrotron source begins to dominate the focused spot size at higher energies. The transition from diffraction-limited to electron-beam-size-limited performance is a function of storage-ring parameters and the optical demagnification within the beamline and microscope optics. The discussion includes how different facilities, beamlines and microscopes will affect the achievable spatial resolution. As synchrotron light sources and other next-generation accelerators such as energy-recovery LINACs and free-electron lasers achieve smaller beam emittances, beta-functions and/or energy spreads, diffraction-limited performance can continue to higher-energy beams, perhaps ultimately into the extreme ultraviolet.

  3. Colored Diffraction Catastrophes

    NASA Astrophysics Data System (ADS)

    Berry, M. V.; Klein, S.

    1996-03-01

    On fine scales, caustics produced with white light show vividly colored diffraction fringes. For caustics described by the elementary catastrophes of singularity theory, the colors are characteristic of the type of singularity. We study the diffraction colors of the fold and cusp catastrophes. The colors can be simulated computationally as the superposition of monochromatic patterns for different wavelengths. Far from the caustic, where the luminosity contrast is negligible, the fringe colors persist; an asymptotic theory explains why. Experiments with caustics produced by refraction through irregular bathroom-window glass show good agreement with theory. Colored fringes near the cusp reveal fine lines that are not present in any of the monochromatic components; these lines are explained in terms of partial decoherence between rays with widely differing path differences.

  4. Central diffraction at ALICE

    NASA Astrophysics Data System (ADS)

    Lämsä, J. W.; Orava, R.

    2011-02-01

    The ALICE experiment is shown to be well suited for studies of exclusive final states from central diffractive reactions. The gluon-rich environment of the central system allows detailed QCD studies and searches for exotic meson states, such as glueballs, hybrids and new charmonium-like states. It would also provide a good testing ground for detailed studies of heavy quarkonia. Due to its central barrel performance, ALICE can accurately measure the low-mass central systems with good purity. The efficiency of the Forward Multiplicity Detector (FMD) and the Forward Shower Counter (FSC) system for detecting rapidity gaps is shown to be adequate for the proposed studies. With this detector arrangement, valuable new data can be obtained by tagging central diffractive processes.

  5. Colored diffraction catastrophes.

    PubMed Central

    Berry, M V; Klein, S

    1996-01-01

    On fine scales, caustics produced with white light show vividly colored diffraction fringes. For caustics described by the elementary catastrophes of singularity theory, the colors are characteristic of the type of singularity. We study the diffraction colors of the fold and cusp catastrophes. The colors can be simulated computationally as the superposition of monochromatic patterns for different wavelengths. Far from the caustic, where the luminosity contrast is negligible, the fringe colors persist; an asymptotic theory explains why. Experiments with caustics produced by refraction through irregular bathroom-window glass show good agreement with theory. Colored fringes near the cusp reveal fine lines that are not present in any of the monochromatic components; these lines are explained in terms of partial decoherence between rays with widely differing path differences. Images Fig. 1 Fig. 2 Fig. 3 Fig. 6 Fig. 8 Fig. 9 Fig. 10 PMID:11607642

  6. Dimensional stability. [of glass and glass-ceramic materials in diffraction telescopes

    NASA Technical Reports Server (NTRS)

    Hochen, R.; Justie, B.

    1976-01-01

    The temporal stability of glass and glass-ceramic materials is important to the success of a large diffraction-limited telescope. The results are presented of an experimental study of the dimensional stability of glasses and glass ceramics being considered for substrates of massive diffraction-limited mirrors designed for several years of service in earth orbit. The purpose of the study was to measure the relative change in length of the candidate substrate materials, to the order of 5 parts in 10 to the 8th power, as a function of several years time. The development of monolithic test etalons, the development and improvement of two types of ultra-high precision interferometers, and certain aspects of tests data presently achieved are discussed.

  7. Biological imaging by soft X-ray diffraction microscopy

    NASA Astrophysics Data System (ADS)

    Shapiro, David

    We have developed a microscope for soft x-ray diffraction imaging of dry or frozen hydrated biological specimens. This lensless imaging system does not suffer from the resolution or specimen thickness limitations that other short wavelength microscopes experience. The microscope, currently situated at beamline 9.0.1 of the Advanced Light Source, can collect diffraction data to 12 nm resolution with 750 eV photons and 17 nm resolution with 520 eV photons. The specimen can be rotated with a precision goniometer through an angle of 160 degrees allowing for the collection of nearly complete three-dimensional diffraction data. The microscope is fully computer controlled through a graphical user interface and a scripting language automates the collection of both two-dimensional and three-dimensional data. Diffraction data from a freeze-dried dwarf yeast cell, Saccharomyces cerevisiae carrying the CLN3-1 mutation, was collected to 12 run resolution from 8 specimen orientations spanning a total rotation of 8 degrees. The diffraction data was phased using the difference map algorithm and the reconstructions provide real space images of the cell to 30 nm resolution from each of the orientations. The agreement of the different reconstructions provides confidence in the recovered, and previously unknown, structure and indicates the three dimensionality of the cell. This work represents the first imaging of the natural complex refractive contrast from a whole unstained cell by the diffraction microscopy method and has achieved a resolution superior to lens based x-ray tomographic reconstructions of similar specimens. Studies of the effects of exposure to large radiation doses were also carried out. It was determined that the freeze-dried cell suffers from an initial collapse, which is followed by a uniform, but slow, shrinkage. This structural damage to the cell is not accompanied by a diminished ability to see small features in the specimen. Preliminary measurements on frozen

  8. Cherokee Culture and School Achievement.

    ERIC Educational Resources Information Center

    Brown, Anthony D.

    1980-01-01

    Compares the effect of cooperative and competitive behaviors of Cherokee and Anglo American elementary school students on academic achievement. Suggests changes in teaching techniques and lesson organization that might raise academic achievement while taking into consideration tribal traditions that limit scholastic achievement in an…

  9. Pulsed photothermal deflection and diffraction effects: numerical modeling based on Fresnel diffraction theory

    NASA Astrophysics Data System (ADS)

    Han, Yue; Wu, Z. L.; Rosenshein, Joseph S.; Thomsen, Marshall; Zhao, Qiang; Moncur, Kent

    1999-12-01

    We present a comprehensive theoretical model suitable for treating the effect of pulsed collinear photothermal deflection spectroscopy (PDS). The work is an extension of the theoretical model previously developed for the mirage effect, which can take into account both photothermal deflection and photothermal diffraction effects based on the Fresnel diffraction theory. With the diffraction model, both the collinear PDS and the photothermal lensing spectroscopy techniques can be treated in a unified manner. The model provides a detailed analysis of the laser-induced optical diffraction effect and can be used to optimize experimental parameters. The modeled results are presented in detail, with an emphasis on the advantages of using a near-field detection scheme for achieving the best sensitivity to local temperature change and better experimental stability against environmental noise.

  10. Diffractive X-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    Skinner, Gerald K.

    2010-01-01

    Diffractive X-ray telescopes, using zone plates, phase Fresnel lenses, or related optical elements have the potential to provide astronomers with true imaging capability with resolution many orders of magnitude better than available in any other waveband. Lenses that would be relatively easy to fabricate could have an angular resolution of the order of micro-arc-seconds or even better, that would allow, for example, imaging of the distorted spacetime in the immediate vicinity of the super-massive black holes in the center of active galaxies. What then is precluding their immediate adoption? Extremely long focal lengths, very limited bandwidth, and difficulty stabilizing the image are the main problems. The history, and status of the development of such lenses is reviewed here and the prospects for managing the challenges that they present are discussed.

  11. Diffraction of a Laser Beam.

    ERIC Educational Resources Information Center

    Jodoin, Ronald E.

    1979-01-01

    Investigates the effect of the nonuniform irradiance across a laser beam on diffraction of the beam, specifically the Fraunhofer diffraction of a laser beam with a Gaussian irradiance profile as it passes through a circular aperture. (GA)

  12. Aberrations of diffracted wave fields. II. Diffraction gratings.

    PubMed

    Mahajan, V N

    2000-12-01

    The Rayleigh-Sommerfeld theory is applied to diffraction of a spherical wave by a grating. The grating equation is obtained from the aberration-free diffraction pattern, and its aberrations are shown to be the same as the conventional aberrations obtained by using Fermat's principle. These aberrations are shown to be not associated with the diffraction process. Moreover, it is shown that the irradiance distribution of a certain diffraction order is the Fraunhofer diffraction pattern of the grating aperture as a whole aberrated by the aberration of that order. PMID:11140481

  13. Recent diffractive results from HERA

    NASA Astrophysics Data System (ADS)

    Valkárová, Alice

    2016-07-01

    The diffractive dijet cross sections for photoproduction and deep inelastic scattering were studied and compared with theoretical NLO QCD predictions. The results of exclusive dijet production were compared to predictions from models which are based on different assumptions about the nature of diffractive exchange. Isolated prompt photons in diffractive photoproduction produced inclusively or together with a jet were studied for the first time.

  14. Hard diffractive results and prospects at the Tevatron

    SciTech Connect

    Peters, Krisztian; /Manchester U.

    2006-01-01

    We review hard diffractive results and prospects at the Tevatron with an emphasis on factorization breaking in diffractive processes. Upper limits on the exclusive di-jet and {chi}{sub c}{sup 0} production cross sections at CDF and the status of the D0 Forward Proton Detectors are discussed.

  15. Hard diffraction in Pythia 8

    NASA Astrophysics Data System (ADS)

    Overgaard Rasmussen, Christine

    2016-07-01

    We present an overview of the options for diffraction implemented in the general-purpose event generator Pythia 8 [1]. We review the existing model for soft diffraction and present a new model for hard diffraction. Both models use the Pomeron approach pioneered by Ingelman and Schlein, factorising the diffractive cross section into a Pomeron flux and a Pomeron PDF, with several choices for both implemented in Pythia 8. The model of hard diffraction is implemented as a part of the multiparton interactions (MPI) framework, thus introducing a dynamical gap survival probability that explicitly breaks factorisation.

  16. Final Report: Algorithms for Diffractive Microscopy

    SciTech Connect

    Elser, Veit

    2010-10-08

    The phenomenal coherence and brightness of x-ray free-electron laser light sources, such as the LCLS at SLAC, have the potential of revolutionizing the investigation of structure and dynamics in the nano-domain. However, this potential will go unrealized without a similar revolution in the way the data are analyzed. While it is true that the ambitious design parameters of the LCLS have been achieved, the prospects of realizing the most publicized goal of this instrument — the imaging of individual bio-particles — remains daunting. Even with 10{sup 12} photons per x-ray pulse, the feebleness of the scattering process represents a fundamental limit that no amount of engineering ingenuity can overcome. Large bio-molecules will scatter on the order of only 10{sup 3} photons per pulse into a detector with 106 pixels; the diffraction “images” will be virtually indistinguishable from noise. Averaging such noisy signals over many pulses is not possible because the particle orientation cannot be controlled. Each noisy laser snapshot is thus confounded by the unknown viewpoint of the particle. Given the heavy DOE investment in LCLS and the profound technical challenges facing single-particle imaging, the final two years of this project have concentrated on this effort. We are happy to report that we succeeded in developing an extremely efficient algorithm that can reconstruct the shapes of particles at even the extremes of noise expected in future LCLS experiments with single bio-particles. Since this is the most important outcome of this project, the major part of this report documents this accomplishment. The theoretical techniques that were developed for the single-particle imaging project have proved useful in other imaging problems that are described at the end of the report.

  17. Structured beam diffraction.

    PubMed

    Castagna, R; Di Donato, A; Nucara, L; Xu, J H; Lucchetta, D E; Simoni, F

    2016-04-01

    We report on the observation of a modulated pattern induced by a single laser beam in a polymeric film. In spite of the simple geometrical configuration, the analysis of the far field diffraction pattern allows a sensitive retrieving of the wavelength of the recording beam and of its incidence angle, pointing out the high information content of the recorded spot. A theoretical model is presented which satisfactorily explains the observed behavior. It takes into account the interaction of structured light with structured matter with the same symmetries and spatial modulation frequencies close to each other. This result shows a feature of the interaction between structured light and structured matter which has not been explored yet. PMID:27192262

  18. Multilayer diffraction grating

    DOEpatents

    Barbee, Jr., Troy W.

    1990-01-01

    This invention is for a reflection diffraction grating that functions at X-ray to VUV wavelengths and at normal angles of incidence. The novel grating is comprised of a laminar grating of period D with flat-topped grating bars. A multiplicity of layered synthetic microstructures, of period d and comprised of alternating flat layers of two different materials, are disposed on the tops of the grating bars of the laminar grating. In another embodiment of the grating, a second multiplicity of layered synthetic microstructures are also disposed on the flat faces, of the base of the grating, between the bars. D is in the approximate range from 3,000 to 50,000 Angstroms, but d is in the approximate range from 10 to 400 Angstroms. The laminar grating and the layered microstructures cooperatively interact to provide many novel and beneficial instrumentational advantages.

  19. Multilayer diffraction grating

    DOEpatents

    Barbee, T.W. Jr.

    1990-04-10

    This invention is for a reflection diffraction grating that functions at X-ray to VUV wavelengths and at normal angles of incidence. The novel grating is comprised of a laminar grating of period D with flat-topped grating bars. A multiplicity of layered synthetic microstructures, of period d and comprised of alternating flat layers of two different materials, are disposed on the tops of the grating bars of the laminar grating. In another embodiment of the grating, a second multiplicity of layered synthetic microstructures are also disposed on the flat faces, of the base of the grating, between the bars. D is in the approximate range from 3,000 to 50,000 Angstroms, but d is in the approximate range from 10 to 400 Angstroms. The laminar grating and the layered microstructures cooperatively interact to provide many novel and beneficial instrumentational advantages. 2 figs.

  20. Single Hit Energy-resolved Laue Diffraction

    SciTech Connect

    Patel, Shamim; Suggit, Matthew J.; Stubley, Paul G.; Ciricosta, Orlando; Wark, Justin S.; Higginbotham, Andrew; Hawreliak, James A.; Collins, Gilbert W.; Eggert, Jon H.; Comley, Andrew J.; Foster, John M.

    2015-05-15

    In situ white light Laue diffraction has been successfully used to interrogate the structure of single crystal materials undergoing rapid (nanosecond) dynamic compression up to megabar pressures. However, information on strain state accessible via this technique is limited, reducing its applicability for a range of applications. We present an extension to the existing Laue diffraction platform in which we record the photon energy of a subset of diffraction peaks. This allows for a measurement of the longitudinal and transverse strains in situ during compression. Consequently, we demonstrate measurement of volumetric compression of the unit cell, in addition to the limited aspect ratio information accessible in conventional white light Laue. We present preliminary results for silicon, where only an elastic strain is observed. VISAR measurements show the presence of a two wave structure and measurements show that material downstream of the second wave does not contribute to the observed diffraction peaks, supporting the idea that this material may be highly disordered, or has undergone large scale rotation.

  1. Every Good Virtue You Ever Wanted in a Q-switched Solid-state Laser and More: Monolithic, Diode-pumped, Self-q-switched, Highly Reproducible, Diffraction-limited Nd:yag Laser

    NASA Technical Reports Server (NTRS)

    Chen, Y. C.; Lee, K. K.

    1993-01-01

    The applications of Q-switched lasers are well known, for example, laser radar, laser remote sensing, satellite orbit determination, Moon orbit and 'moon quake' determination, satellite laser communication, and many nonlinear optics applications. Most of the applications require additional properties of the Q-switched lasers, such as single-axial and/or single-transverse mode, high repetition rate, stable pulse shape and pulse width, or ultra compact and rugged oscillators. Furthermore, space based and airborne lasers for lidar and laser communication applications require efficient, compact, lightweight, long-lived, and stable-pulsed laser sources. Diode-pumped solid-state lasers (DPSSL) have recently shown the potential for satisfying all of these requirements. We will report on the operating characteristics of a diode-pumped, monolithic, self-Q-switched Cr,Nd:YAG laser where the chromium ions act as a saturable absorber for the laser emission at 1064 nm. The pulse duration is 3.5 ns and the output is highly polarized with an extinction ratio of 700:1. It is further shown that the output is single-longitudinal-mode with transform-limited spectral line width without pulse-to-pulse mode competition. Consequently, the pulse-to-pulse intensity fluctuation is less than the instrument resolution of 0.25 percent. This self-stabilization mechanism is because the lasing mode bleaches the distributed absorber and establishes a gain-loss grating similar to that used in the distributed feedback semiconductor lasers. A repetition rate above 5 KHz has also been demonstrated. For higher power, this laser can be used for injection seeding an amplifier (or amplifier chain) or injection locking of a power oscillator pumped by diode lasers. We will discuss some research directions on the master oscillator for higher output energy per pulse as well as how to scale the output power of the diode-pumped amplifier(s) to multi-kilowatt average power.

  2. Quantitative biological imaging by ptychographic x-ray diffraction microscopy

    PubMed Central

    Giewekemeyer, Klaus; Thibault, Pierre; Kalbfleisch, Sebastian; Beerlink, André; Kewish, Cameron M.; Dierolf, Martin; Pfeiffer, Franz; Salditt, Tim

    2010-01-01

    Recent advances in coherent x-ray diffractive imaging have paved the way to reliable and quantitative imaging of noncompact specimens at the nanometer scale. Introduced a year ago, an advanced implementation of ptychographic coherent diffractive imaging has removed much of the previous limitations regarding sample preparation and illumination conditions. Here, we apply this recent approach toward structure determination at the nanoscale to biological microscopy. We show that the projected electron density of unstained and unsliced freeze-dried cells of the bacterium Deinococcus radiodurans can be derived from the reconstructed phase in a straightforward and reproducible way, with quantified and small errors. Thus, the approach may contribute in the future to the understanding of the highly disputed nucleoid structure of bacterial cells. In the present study, the estimated resolution for the cells was 85 nm (half-period length), whereas 50-nm resolution was demonstrated for lithographic test structures. With respect to the diameter of the pinhole used to illuminate the samples, a superresolution of about 15 was achieved for the cells and 30 for the test structures, respectively. These values should be assessed in view of the low dose applied on the order of ≃1.3·105 Gy, and were shown to scale with photon fluence. PMID:20018650

  3. Diffraction-based optical correlator

    NASA Technical Reports Server (NTRS)

    Spremo, Stevan M. (Inventor); Fuhr, Peter L. (Inventor); Schipper, John F. (Inventor)

    2005-01-01

    Method and system for wavelength-based processing of a light beam. A light beam, produced at a chemical or physical reaction site and having at least first and second wavelengths, ?1 and ?2, is received and diffracted at a first diffraction grating to provide first and second diffracted beams, which are received and analyzed in terms of wavelength and/or time at two spaced apart light detectors. In a second embodiment, light from first and second sources is diffracted and compared in terms of wavelength and/or time to determine if the two beams arise from the same source. In a third embodiment, a light beam is split and diffracted and passed through first and second environments to study differential effects. In a fourth embodiment, diffracted light beam components, having first and second wavelengths, are received sequentially at a reaction site to determine whether a specified reaction is promoted, based on order of receipt of the beams. In a fifth embodiment, a cylindrically shaped diffraction grating (uniform or chirped) is rotated and translated to provide a sequence of diffracted beams with different wavelengths. In a sixth embodiment, incident light, representing one or more symbols, is successively diffracted from first and second diffraction gratings and is received at different light detectors, depending upon the wavelengths present in the incident light.

  4. Continuous energy diffraction spectroscopy: A new d-space matching technique for energy dispersive synchrotron radiation diffraction

    NASA Astrophysics Data System (ADS)

    Lee, P. L.; Beno, M. A.; Knapp, G. S.; Jennings, G.

    1994-07-01

    In this article, a new technique, continuous energy diffraction spectroscopy (CEDS) is described, for diffraction experiments using a synchrotron energy dispersive polychromatic beamline. This type of beamline uses a curved crystal monochromator (polychromator) to focus a range of x-ray energies (bandwidth ˜1 keV) into a narrow (100-120 μm) line image. With a sample at this image point, using an 2D detector, we are able to measure diffracted intensities for the entire energy range of the incident beam simultaneously with limited or no motion of the sample. This method allows the collection of anomalous scattering and diffraction anomalous fine structure (DAFS) data faster and more accurately than with conventional methods. Because of the speed with which these types of diffraction experiments can be done, this method creates new options for time resolved diffraction experiments and provides new data collection strategies.

  5. Ultrafast electron diffraction from laser-aligned molecules in the gas phase

    NASA Astrophysics Data System (ADS)

    Yang, Jie

    Ultrafast electron diffraction has emerged since the end of last century, and has become an increasingly important tool for revealing great details of molecular dynamics. In comparison to spectroscopic techniques, ultrafast electron diffraction directly probes time-resolved structure of target molecules, and therefore can potentially provide "molecular movies" of the reactions being studied. These molecular movies are critical for understanding and ultimately controlling the energy conversion pathways and efficiencies of photochemical processes. In this dissertation, I have focused on ultrafast electron diffraction from gas-phase molecules, and have investigated several long-standing challenges that have been preventing researchers from being able to achieve 3-D molecular movies of photochemical reactions. The first challenge is to resolve the full 3-D structure for molecules in the gas phase. The random orientation of molecules in the gas phase smears out the diffraction signal, which results in only 1-D structural information being accessible. The second challenge lies in temporal resolution. In order to resolve coherent nuclear motions on their natural time scale, a temporal resolution of ˜200 femtosecond or better is required. However, due to experimental limitations the shortest temporal resolution that had been achieved was only a few picoseconds in early 2000, by Zewail group from Caltech. The first challenge is tackled by laser-alignment. In the first half of the dissertation, I approach this method both theoretically and experimentally, and demonstrate that by using a short laser pulse to transiently align target molecules in space, 3-D molecular structure can be reconstructed ab-initio from diffraction patterns. The second half of the dissertation presents two experiments, both of which are important steps toward imaging coherent nuclear motions in real time during photochemical reactions. The first experiment simultaneously resolves molecular alignment

  6. Detonation diffraction in gases

    SciTech Connect

    Pintgen, F.; Shepherd, J.E.

    2009-03-15

    We have experimentally investigated detonation diffraction out of a round tube into an unconfined half-space. The focus of our study is examining how the extent of detonation cellular instability influences the quantitative and qualitative features of diffraction. Detailed quantitative and qualitative measurements were obtained through simultaneous schlieren imaging, multiple-exposure chemiluminescence imaging, and planar laser-induced fluorescence imaging of OH molecules. Two types of stoichiometric mixtures, highly diluted H{sub 2}-O{sub 2}-Ar and H{sub 2}-N{sub 2}O, were studied in the sub-critical, critical and super-critical regime. These mixture types represent extreme cases in the classification of cellular instability with highly diluted H{sub 2}-O{sub 2}-Ar mixtures having very regular instability structures and H{sub 2}-N{sub 2}O having very irregular instability structures. The most striking differences between the mixtures occur in the sub-critical and critical regimes, for which the detonation fails to transition into the unconfined half-space. For the H{sub 2}-O{sub 2}-Ar mixture, the velocity on the center line was found to decay significantly slower than for the H{sub 2}-N{sub 2}O mixture. In case of the H{sub 2}-O{sub 2}-Ar mixture, it was evident from simultaneous schlieren-fluorescence images that the reaction front was coupled to the lead shock front up to 2.3 tube diameters from the exit plane. For the H{sub 2}-N{sub 2}O mixture, the reaction front velocity decreased to 60% of the corresponding Chapman-Jouguet value at 1.1 tube diameters from the tube exit plane. A geometric acoustic model showed that the observed differences in failure patterns are not caused by the differences in thermodynamic properties of the two mixtures but is linked to the larger effective activation energy and critical decay time in the H{sub 2}-N{sub 2}O mixture as compared to the H{sub 2}-O{sub 2}-Ar mixture. The re-initiation events appear similar for the two

  7. Numerical focusing in diffraction phase microscopy

    NASA Astrophysics Data System (ADS)

    Talaikova, N. A.; Grebenyuk, A. A.; Kalyanov, A. L.; Ryabukho, V. P.

    2016-04-01

    Diffraction phase microscopy (DPM) provides the possibility of high-resolution quantitative phase imaging, based on equipment of an optical microscope with a special module working in a common-path off-axis configuration. As an optical microscopy technique, DPM has a limited focus depth, which is the smaller the higher is the objective's numerical aperture. In this paper we present the results of experimental investigation of numerical focusing with the angular spectrum method in DPM.

  8. Diffraction-Specific Fringe Computation for Electro -

    NASA Astrophysics Data System (ADS)

    Lucente, Mark

    Diffraction-specific fringe computation is a novel system for the generation of holographic fringe patterns for real-time display. This thesis describes the development, implementation, and analysis of diffraction-specific computation, an approach that considers the reconstruction process rather than the interference process in optical holography. The primary goal is to increase the speed of holographic computation for real-time three-dimensional electro-holographic (holovideo) displays. Diffraction-specific fringe computation is based on the discretization of space and spatial frequency in the fringe pattern. Two holographic fringe encoding techniques are developed from diffraction-specific fringe computation and applied to make most efficient use of hologram channel capacity. A "hogel-vector encoding" technique is based on undersampling the fringe spectra. A "fringelet encoding" technique is designed to increase the speed and simplicity of decoding. The analysis of diffraction-specific computation focuses on the trade-offs between compression ratio, image fidelity, and image depth. The decreased image resolution (increased point spread) that is introduced into holographic images due to encoding is imperceptible to the human visual system under certain conditions. A compression ratio of 16 is achieved (using either encoding method) with an acceptably small loss in image resolution. Total computation time is reduced by a factor of over 100 to less than 7.0 seconds per 36-MB holographic fringe using the fringelet encoding method. Diffraction-specific computation more efficiently matches the information content of holographic fringes to the human visual system. Diffraction-specific holographic encoding allows for "visual-bandwidth holography," i.e., holographic imaging that requires a bandwidth commensurate with the usable visual information contained in an image. Diffraction -specific holographic encoding enables the integration of holographic information with other

  9. Diamond turned master molds for bulk casting of sol-gel silica diffractive optical elements. Final report

    SciTech Connect

    Maxey, L.C.; Nogues, J.L.; Moreshead, B.

    1997-08-01

    This CRADA has combined the resources of a national laboratory and an innovative small company to investigate the production of diffractive lenses in silica glass, using diamond turned master molds. The method for producing these lenses combines the unique characteristics of the sol-gel silica replication process, pioneered by Geltech, with the state-of-the-art diamond turning expertise of the Oak Ridge Centers for Manufacturing Technology (ORCMT). A conventional lens focuses light by using a curved surface to refract (or bend) the incoming light so that it will form an image. These lenses are usually thick glass elements with one or both surfaces shaped into convex or concave spherical shapes. Traditionally, these lenses are produced by grinding and polishing the glass to the desired shape. Light can also be focused using the phenomenon of diffraction, rather than refraction. A lens of this type uses precision microscopic surface features to bend the light so that it forms an image. The result is a lens that is thinner and lighter than its refractive counterpart. Production of diffractive lenses requires the ability to accurately produce the precision microscopic features necessary to achieve controlled diffraction. Diffractive lenses have, for the most part, been limited to infra-red applications because the manufacturing technologies available have not enabled their use at visible wavelengths. Except in limited applications, these lenses have remained laboratory curiosities, because they must be individually produced by diamond turning infra-red optical materials. Geltech`s sol-gel silica replication process offers the opportunity to mass produce diffractive lenses in high quality silica glass. These lenses can be produced by diamond turning the necessary precision microscopic surface features into master surfaces that are replicated into intermediate molds. These molds are then used to produce a batch of diffractive lenses using the sol-gel process.

  10. Study of optical Laue diffraction

    SciTech Connect

    Chakravarthy, Giridhar E-mail: aloksharan@email.com; Allam, Srinivasa Rao E-mail: aloksharan@email.com; Satyanarayana, S. V. M. E-mail: aloksharan@email.com; Sharan, Alok E-mail: aloksharan@email.com

    2014-10-15

    We present the study of the optical diffraction pattern of one and two-dimensional gratings with defects, designed using desktop pc and printed on OHP sheet using laser printer. Gratings so prepared, using novel low cost technique provides good visual aid in teaching. Diffraction pattern of the monochromatic light (632.8nm) from the grating so designed is similar to that of x-ray diffraction pattern of crystal lattice with point defects in one and two-dimensions. Here both optical and x-ray diffractions are Fraunhofer. The information about the crystalline lattice structure and the defect size can be known.

  11. Electrically-programmable diffraction grating

    DOEpatents

    Ricco, Antonio J.; Butler, Michael A.; Sinclair, Michael B.; Senturia, Stephen D.

    1998-01-01

    An electrically-programmable diffraction grating. The programmable grating includes a substrate having a plurality of electrodes formed thereon and a moveable grating element above each of the electrodes. The grating elements are electrostatically programmable to form a diffraction grating for diffracting an incident beam of light as it is reflected from the upper surfaces of the grating elements. The programmable diffraction grating, formed by a micromachining process, has applications for optical information processing (e.g. optical correlators and computers), for multiplexing and demultiplexing a plurality of light beams of different wavelengths (e.g. for optical fiber communications), and for forming spectrometers (e.g. correlation and scanning spectrometers).

  12. Recent CMS results on diffraction

    NASA Astrophysics Data System (ADS)

    Benoît, Roland

    2015-03-01

    Recent CMS results on diffraction are presented. These include the measurements of the soft diffractive cross sections, of the forward rapidity gap cross section, of the diffractive dijet cross section, the measurement of a large rapidity gap in W and Z boson events and the measurement of the pseudorapidity distribution of charged particles in a single diffractive enhanced sample. This last measurement is the first common result of the CMS and TOTEM collaborations. Some prospects of common CMS-TOTEM data taking are also discussed.

  13. Performance of hybrid, diffraction, and continuously coupled cat-eye resonators with kinetically enhanced copper vapor lasers

    NASA Astrophysics Data System (ADS)

    Singh, Bijendra; Subramaniam, V. V.; Daultabad, Shankar; Ghodke, Dharmraj; Chakraborty, Ashim

    2010-09-01

    New resonators, namely the hybrid cat-eye resonator (HCER), diffraction-coupled cat-eye resonator (DCCER), and continuously coupled cat-eye resonator (CCCER) are demonstrated for the first time here in a kinetically enhanced copper vapor laser with high optical extraction of 70 to 80%, low beam divergence ~0.15 mrad (approximately five times the diffraction limit), and high misalignment tolerance ~5 to 6 mrad achieved simultaneously from each of these configurations. The laser used in the experiment is a 45- to 47-mm bore, 50-W kinetically enhanced copper vapor laser. In the case of HCER, the laser beam divergence reduces to about 0.12 mrad (~30-fold reduction) in an unstable direction and about 0.5 mrad (approximately seven-fold reduction) in a stable direction with average beam power of about 35 W, which is ~70% of 50-W maximum set power of the laser. In the DCCER configuration, laser power achieved is about ~37 W (75% of 50-W laser power) with beam divergence of about 0.17 mrad and misalignment tolerance of ~5 mrad. In CCCER, the output power of about 40 W (80% of 50-W laser power) is achieved with beam divergence of about 0.1 mrad (approximately three to four times the diffraction limit).

  14. Spectrometer design approaching the limit

    NASA Astrophysics Data System (ADS)

    Riesenberg, Rainer; Wuttig, Andreas; Peschel, Thomas; Damm, Christoph; Dobschal, Hans-Jürgen

    2008-09-01

    The design limits of grating array spectral sensors are discussed. The limit of a grating spectrometer with respect to the resolution is given by the diffraction limit of the grating. To approach the limit for the visible spectral region the entrance slits should reach a width of 2 μm and larger depending on wavelength and numerical aperture. The detector pixel sizes should be in the same range, which is achieved virtually by the discussed double array arrangement with a transmissive, static slit array and detector array. A number of techniques are applied for optimizing the performance as well as for miniaturization. A sub-pixel imaging including a sub-pixel analysis based on the double array arrangement virtually reduces the detector pixel sizes down to about 20%. To avoid the imaging aberrations the spectra is imaged from different entrance positions by the entrance slit array. The throughput can be increased by using a two dimensional entrance slit array, which includes a multiplex pattern or a fixed adaptive pattern. The design example of a UV-Raman spectral sensor is presented including spectral measurements.

  15. Digital electron diffraction – seeing the whole picture

    SciTech Connect

    Beanland, Richard; Thomas, Paul J.; Woodward, David I.; Thomas, Pamela A.; Roemer, Rudolf A.

    2013-07-01

    Computer control of beam tilt and image capture allows the collection of electron diffraction patterns over a large angular range, without any overlap in diffraction data and from a region limited only by the size of the electron beam. This results in a significant improvement in data volumes and ease of interpretation. The advantages of convergent-beam electron diffraction for symmetry determination at the scale of a few nm are well known. In practice, the approach is often limited due to the restriction on the angular range of the electron beam imposed by the small Bragg angle for high-energy electron diffraction, i.e. a large convergence angle of the incident beam results in overlapping information in the diffraction pattern. Techniques have been generally available since the 1980s which overcome this restriction for individual diffracted beams, by making a compromise between illuminated area and beam convergence. Here a simple technique is described which overcomes all of these problems using computer control, giving electron diffraction data over a large angular range for many diffracted beams from the volume given by a focused electron beam (typically a few nm or less). The increase in the amount of information significantly improves the ease of interpretation and widens the applicability of the technique, particularly for thin materials or those with larger lattice parameters.

  16. Diffraction contrast imaging using virtual apertures.

    PubMed

    Gammer, Christoph; Burak Ozdol, V; Liebscher, Christian H; Minor, Andrew M

    2015-08-01

    Two methods on how to obtain the full diffraction information from a sample region and the associated reconstruction of images or diffraction patterns using virtual apertures are demonstrated. In a STEM-based approach, diffraction patterns are recorded for each beam position using a small probe convergence angle. Similarly, a tilt series of TEM dark-field images is acquired. The resulting datasets allow the reconstruction of either electron diffraction patterns, or bright-, dark- or annular dark-field images using virtual apertures. The experimental procedures of both methods are presented in the paper and are applied to a precipitation strengthened and creep deformed ferritic alloy with a complex microstructure. The reconstructed virtual images are compared with conventional TEM images. The major advantage is that arbitrarily shaped virtual apertures generated with image processing software can be designed without facing any physical limitations. In addition, any virtual detector that is specifically designed according to the underlying crystal structure can be created to optimize image contrast. PMID:25840371

  17. Diffraction limited operation with ARGOS: a hybrid AO system

    NASA Astrophysics Data System (ADS)

    Bonaglia, M.; Busoni, L.; Quirós-Pacheco, F.; Esposito, S.

    2010-07-01

    ARGOS, the Laser Guide Star (LGS) facility of the Large Binocular Telescope (LBT), implements a Ground Layer Adaptive Optics (GLAO) system, using 3 low-altitude beacons, to improve the resolution over the 4'×4' FoV of the imager and Multi Object Spectrograph (MOS) LUCIFER. In this paper we discuss the performance and the reconstruction scheme of an hybrid AO system using the ARGOS Rayleigh beacons complemented with a single faint high-altitude star (NGS or sodium beacon) to sense the turbulence of the upper atmosphere allowing an high degree of on-axis correction. With the ARGOS system, the NGS-upgrade can be immediately implemented at LBT using the already existing Pyramid WFS offering performance similar to the NGS AO system with the advantage of a larger sky coverage.

  18. Infrared Imaging and Spectroscopy Beyond the Diffraction Limit

    NASA Astrophysics Data System (ADS)

    Centrone, Andrea

    2015-07-01

    Progress in nanotechnology is enabled by and dependent on the availability of measurement methods with spatial resolution commensurate with nanomaterials' length scales. Chemical imaging techniques, such as scattering scanning near-field optical microscopy (s-SNOM) and photothermal-induced resonance (PTIR), have provided scientists with means of extracting rich chemical and structural information with nanoscale resolution. This review presents some basics of infrared spectroscopy and microscopy, followed by detailed descriptions of s-SNOM and PTIR working principles. Nanoscale spectra are compared with far-field macroscale spectra, which are widely used for chemical identification. Selected examples illustrate either technical aspects of the measurements or applications in materials science. Central to this review is the ability to record nanoscale infrared spectra because, although chemical maps enable immediate visualization, the spectra provide information to interpret the images and characterize the sample. The growing breadth of nanomaterials and biological applications suggest rapid growth for this field.

  19. Future of Electron Scattering and Diffraction

    SciTech Connect

    Hall, Ernest; Stemmer, Susanne; Zheng, Haimei; Zhu, Yimei; Maracas, George

    2014-02-25

    spectroscopy with high spatial resolution without damaging their structure. The strong interaction of electrons with matter allows high-energy electron pulses to gather structural information before a sample is damaged. Electron ScatteringImaging, diffraction, and spectroscopy are the fundamental capabilities of electron-scattering instruments. The DOE BES-funded TEAM (Transmission Electron Aberration-corrected Microscope) project achieved unprecedented sub-atomic spatial resolution in imaging through aberration-corrected transmission electron microscopy. To further advance electron scattering techniques that directly enable groundbreaking science, instrumentation must advance beyond traditional two-dimensional imaging. Advances in temporal resolution, recording the full phase and energy spaces, and improved spatial resolution constitute a new frontier in electron microscopy, and will directly address the BES Grand Challenges, such as to “control the emergent properties that arise from the complex correlations of atomic and electronic constituents” and the “hidden states” “very far away from equilibrium”. Ultrafast methods, such as the pump-probe approach, enable pathways toward understanding, and ultimately controlling, the chemical dynamics of molecular systems and the evolution of complexity in mesoscale and nanoscale systems. Central to understanding how to synthesize and exploit functional materials is having the ability to apply external stimuli (such as heat, light, a reactive flux, and an electrical bias) and to observe the resulting dynamic process in situ and in operando, and under the appropriate environment (e.g., not limited to UHV conditions). To enable revolutionary advances in electron scattering and science, the participants of the workshop recommended three major new instrumental developments: A. Atomic-Resolution Multi-Dimensional Transmission Electron Microscope: This instrument would provide quantitative information over the entire real space

  20. Quasi-steady state principle and in-situ real-time investigation of transient strains in 6061-T6 Al alloy using neutron diffraction

    SciTech Connect

    Woo, Wan Chuck; Brown, D. W.; Choo, Hahn; Clausen, B; David, Stan A; Feng, Zhili; Hubbard, Camden R; Wang, Xun-Li

    2007-01-01

    Neutron diffraction research has been limited to the "static" behavior of materials since the number of collected neutrons is insufficient to reach the adequate neutron counts in rapid changes of material state. In order to achieve the desired precision for the study of the transient material behavior, we propose an in-situ neutron-diffraction measurement method based on the quasi-steady state (QSS) phenomenon. The QSS principle was applied for the measurement of transient lattice spacing changes in a 6061-T6 aluminum alloy plate during thermo-mechanical processing.

  1. Results on diffraction at CDF

    SciTech Connect

    Wyatt, A.

    2003-10-27

    In run I CDF made an extensive range of measurements studying diffractive processes. In run II these measurements can be extended using improved triggering, new detectors and larger data samples. In these proceedings run II measurements of single diffractive dijet production and double pomeron exchange production of dijets are presented.

  2. Computer Simulation of Diffraction Patterns.

    ERIC Educational Resources Information Center

    Dodd, N. A.

    1983-01-01

    Describes an Apple computer program (listing available from author) which simulates Fraunhofer and Fresnel diffraction using vector addition techniques (vector chaining) and allows user to experiment with different shaped multiple apertures. Graphics output include vector resultants, phase difference, diffraction patterns, and the Cornu spiral…

  3. Phase-shifting point-diffraction interferometry at EUV wavelengths

    SciTech Connect

    Goldberg, K.A.; Tejnil, E.; Sang Lee

    1997-04-01

    A novel phase-shifting point-diffraction interferometer (PS/PDI) operating at the Advanced Light Source (ALS) is being used to perform wavefront-measuring metrology at 13.4-nm wavelength to characterize aberrations in a multilayer-coated 10x Schwarzschild objective designed for extreme ultraviolet (EUV) projection lithography experiments. To achieve 0.1-micron critical dimension pattern transfer with EUV projection lithography at 13.4-nm wavelength, nearly diffraction-limited all-reflective multilayer-coated optical systems with 0.1 numerical aperture are required. The EUV wavefront, determined by the mirror surfaces and the reflective multilayer coatings, is measurable only at the operational wavelength of the system. The authors goal is to measure the EUV wavefront to an accuracy of 0.01 waves rms (0.13 nm). The PS/PDI is a type of point-diffraction interferometer, modified for significantly improved throughput and phase-shifting capability. The interferometer design utilizes a grating beamsplitter and pinhole spatial filters in the object and image planes of the optical system under test. The 10x-reduction Schwarzschild objective, with image-side numerical aperture of 0.08, is illuminated by a sub-micron pinhole in the object plane. A coarse, 20-micron pitch grating placed between the illumination pinhole and the Schwarzschild system serves a dual role as a small-angle beam-splitter and a phase-shifting element. The first-order diffracted beam from the grating is spatially filtered in the image plane of the Schwarzschild with a sub-100-nm pinhole and becomes the `D reference` wave in the interferometer. The zero-order beam is the `test` wave, and it passes unobstructed through a 4.5-{mu}m window in the image plane. The test and reference beams are separated by several microns in the image plane to minimize beam overlap. The interference fringes are recorded with a CCD detector placed about 12 cm from the Schwarzschild image plane.

  4. High-Resolution Atom Interferometers with Suppressed Diffraction Phases.

    PubMed

    Estey, Brian; Yu, Chenghui; Müller, Holger; Kuan, Pei-Chen; Lan, Shau-Yu

    2015-08-21

    We experimentally and theoretically study the diffraction phase of large-momentum transfer beam splitters in atom interferometers based on Bragg diffraction. We null the diffraction phase and increase the sensitivity of the interferometer by combining Bragg diffraction with Bloch oscillations. We demonstrate agreement between experiment and theory, and a 1500-fold reduction of the diffraction phase, limited by measurement noise. In addition to reduced systematic effects, our interferometer has high contrast with up to 4.4×10(6) radians of phase difference, and a resolution in the fine structure constant of δα/α=0.25  ppb in 25 h of integration time. PMID:26340186

  5. Flat liquid crystal diffractive lenses with variable focus and magnification

    NASA Astrophysics Data System (ADS)

    Valley, Pouria

    Non-mechanical variable lenses are important for creating compact imaging devices. Various methods employing dielectrically actuated lenses, membrane lenses, and liquid crystal lenses were previously proposed [1-4]. In This dissertation the design, fabrication, and characterization of innovative flat tunable-focus liquid crystal diffractive lenses (LCDL) are presented. LCDL employ binary Fresnel zone electrodes fabricated on Indium-Tin-Oxide using conventional micro-photolithography. The light phase can be adjusted by varying the effective refractive index of a nematic liquid crystal sandwiched between the electrodes and a reference substrate. Using a proper voltage distribution across various electrodes the focal length can be changed between several discrete values. Electrodes are shunted such that the correct phase retardation step sequence is achieved. If the number of 2pi zone boundaries is increased by a factor of m the focal length is changed from f to f/m based on the digitized Fresnel zone equation: f = rm2/2mlambda, where r m is mth zone radius, and lambda is the wavelength. The chromatic aberration of the diffractive lens is addressed and corrected by adding a variable fluidic lens. These LCDL operate at very low voltage levels (+/-2.5V ac input), exhibit fast switching times (20-150 ms), can have large apertures (>10 mm), and small form factor, and are robust and insensitive to vibrations, gravity, and capillary effects that limit membrane and dielectrically actuated lenses. Several tests were performed on the LCDL including diffraction efficiency measurement, switching dynamics, and hybrid imaging with a refractive lens. Negative focal lengths are achieved by adjusting the voltages across electrodes. Using these lenses in combination, magnification can be changed and zoom lenses can be formed. These characteristics make LCDL a good candidate for a variety of applications including auto-focus and zoom lenses in compact imaging devices such as camera

  6. Diffraction-managed superlensing using plasmonic lattices

    NASA Astrophysics Data System (ADS)

    Zapata-Rodríguez, Carlos J.; Pastor, David; Caballero, María T.; Miret, Juan J.

    2012-07-01

    We show that subwavelength diffracted wave fields may be managed inside multilayered plasmonic devices to achieve ultra-resolving lensing. For that purpose we first transform both homogeneous waves and a broad band of evanescent waves into propagating Bloch modes by means of a metal/dielectric (MD) superlattice. Beam spreading is subsequently compensated by means of negative refraction in a plasmon-induced anisotropic medium that is cemented behind. A precise design of the superlens doublet may lead to nearly aberration-free images with subwavelength resolution in spite of using optical paths longer than a wavelength.

  7. Diffraction-managed superlensing using metallodielectric heterostructures

    NASA Astrophysics Data System (ADS)

    Zapata-Rodríguez, Carlos J.; Pastor, David; Caballero, María T.; Miret, Juan J.

    2012-05-01

    We show that subwavelength diffracted wave fields may be managed inside multilayered plasmonic devices to achieve ultra-resolving lensing. For that purpose we first transform both homogeneous waves and a broad band of evanescent waves into propagating Bloch modes by means of a metal/dielectric (MD) superlattice. Beam spreading is subsequently compensated by means of negative refraction in a plasmon-induced anisotropic effective-medium that is cemented behind. A precise design of the superlens doublet may lead to nearly aberration-free images with subwavelength resolution in spite of using optical paths longer than a wavelength.

  8. Electromagnetic diffraction efficiencies for plane reflection diffraction gratings

    NASA Technical Reports Server (NTRS)

    Marathay, A. S.; Shrode, T. E.

    1973-01-01

    Results are presented of research activities on holographic grating research. A large portion of this work was performed using rigorous vector diffraction theory, therefore, the necessary theory has been included in this report. The diffraction efficiency studies were continued using programs based on a rigorous theory. The simultaneous occurrence of high diffraction efficiencies and the phenomenon of double Wood's anomalies is demonstrated along with a graphic method for determining the necessary grating parameters. Also, an analytical solution for a grating profile that is perfectly blazed is obtained. The performance of the perfectly blazed grating profile is shown to be significantly better than grating profiles previously studied. Finally, a proposed method is described for the analysis of coarse echelle gratings using rigorous vector diffraction that is currently being developed.

  9. Diffraction dissociation at the LHC

    NASA Astrophysics Data System (ADS)

    Jenkovszky, László; Orava, Risto; Salii, Andrii

    2013-04-01

    We report on recent calculations of low missing mass single (SD) and double (DD) diffractive dissociation at LHC energies. The calculations are based on a dual-Regge model, dominated by a single Pomeron exchange. The diffractively excited states lie on the nucleon trajectory N*, appended by the isolated Roper resonance. Detailed predictions for the squared momentum transfer and missing mass dependence of the differential and integrated single-and double diffraction dissociation in the kinematical range of present and future LHC measurements are given.

  10. Diffraction dissociation at the LHC

    SciTech Connect

    Jenkovszky, Laszlo; Orava, Risto; Salii, Andrii

    2013-04-15

    We report on recent calculations of low missing mass single (SD) and double (DD) diffractive dissociation at LHC energies. The calculations are based on a dual-Regge model, dominated by a single Pomeron exchange. The diffractively excited states lie on the nucleon trajectory N*, appended by the isolated Roper resonance. Detailed predictions for the squared momentum transfer and missing mass dependence of the differential and integrated single-and double diffraction dissociation in the kinematical range of present and future LHC measurements are given.

  11. Diffraction techniques in engineering applications

    SciTech Connect

    Kozarczek, K.J.; Hubbard, C.R.; Watkins, T.R.; Wang, X.L.; Spooner, S.

    1995-12-31

    Diffraction techniques applied to crystalline materials provide quantitative information about the crystallographic structure and mechanical condition of the material. Those two characteristics influence the chemical, physical, and mechanical properties of a Component. A concerted application of x-ray and neutron diffraction allows one to comprehensively study the bulk and subsurface variations of such material characteristics as crystallographic texture, residual stress, and cold work. The Residual Stress User Center at the Oak Ridge National Laboratory offers academic and industrial researchers both neutron and x-ray diffraction capabilities. Recent examples of the application of work related to thin film, metal, ceramic and composite material technologies are presented.

  12. Recovering magnetization distributions from their noisy diffraction data

    SciTech Connect

    Loh, Ne-Te Duane; Eisebitt, Stefan; Flewett, Samuel; Elser, Veit

    2010-12-15

    We study, using simulated experiments inspired by thin-film magnetic domain patterns, the feasibility of phase retrieval in x-ray diffractive imaging in the presence of intrinsic charge scattering given only photon-shot-noise limited diffraction data. We detail a reconstruction algorithm to recover the sample's magnetization distribution under such conditions and compare its performance with that of Fourier transform holography. Concerning the design of future experiments, we also chart out the reconstruction limits of diffractive imaging when photon-shot-noise and the intensity of charge scattering noise are independently varied. This work is directly relevant to the time-resolved imaging of magnetic dynamics using coherent and ultrafast radiation from x-ray free-electron lasers and also to broader classes of diffractive imaging experiments which suffer noisy data, missing data, or both.

  13. Atomic-Resolution 3D Electron Microscopy with Dynamic Diffraction

    SciTech Connect

    O'Keefe, Michael A.; Downing, Kenneth H.; Wenk, Hans-Rudolf; Meisheng, Hu

    2005-02-15

    Achievement of atomic-resolution electron-beam tomography will allow determination of the three-dimensional structure of nanoparticles (and other suitable specimens) at atomic resolution. Three-dimensional reconstructions will yield ''section'' images that resolve atoms overlapped in normal electron microscope images (projections), resolving lighter atoms such as oxygen in the presence of heavier atoms, and atoms that lie on non-lattice sites such as those in non-periodic defect structures. Lower-resolution electron microscope tomography has been used to produce reconstructed 3D images of nanoparticles [1] but extension to atomic resolution is considered not to be straightforward. Accurate three-dimensional reconstruction from two-dimensional projections generally requires that intensity in the series of 2-D images be a monotonic function of the specimen structure (often specimen density, but in our case atomic potential). This condition is not satisfied in electron microscopy when specimens with strong periodicity are tilted close to zone-axis orientation and produce ''anomalous'' image contrast because of strong dynamic diffraction components. Atomic-resolution reconstructions from tilt series containing zone-axis images (with their contrast enhanced by strong dynamical scattering) can be distorted when the stronger zone-axis images overwhelm images obtained in other ''random'' orientations in which atoms do not line up in neat columns. The first demonstrations of 3-D reconstruction to atomic resolution used five zone-axis images from test specimens of staurolite consisting of a mix of light and heavy atoms [2,3]. Initial resolution was to the 1.6{angstrom} Scherzer limit of a JEOL-ARM1000. Later experiments used focal-series reconstruction from 5 to 10 images to produce staurolite images from the ARM1000 with resolution extended beyond the Scherzer limit to 1.38{angstrom} [4,5]. To obtain a representation of the three-dimensional structure, images were obtained

  14. X-Ray Diffraction Apparatus

    NASA Technical Reports Server (NTRS)

    Blake, David F. (Inventor); Bryson, Charles (Inventor); Freund, Friedmann (Inventor)

    1996-01-01

    An x-ray diffraction apparatus for use in analyzing the x-ray diffraction pattern of a sample is introduced. The apparatus includes a beam source for generating a collimated x-ray beam having one or more discrete x-ray energies, a holder for holding the sample to be analyzed in the path of the beam, and a charge-coupled device having an array of pixels for detecting, in one or more selected photon energy ranges, x-ray diffraction photons produced by irradiating such a sample with said beam. The CCD is coupled to an output unit which receives input information relating to the energies of photons striking each pixel in the CCD, and constructs the diffraction pattern of photons within a selected energy range striking the CCD.

  15. Electrically-programmable diffraction grating

    DOEpatents

    Ricco, A.J.; Butler, M.A.; Sinclair, M.B.; Senturia, S.D.

    1998-05-26

    An electrically-programmable diffraction grating is disclosed. The programmable grating includes a substrate having a plurality of electrodes formed thereon and a moveable grating element above each of the electrodes. The grating elements are electrostatically programmable to form a diffraction grating for diffracting an incident beam of light as it is reflected from the upper surfaces of the grating elements. The programmable diffraction grating, formed by a micromachining process, has applications for optical information processing (e.g. optical correlators and computers), for multiplexing and demultiplexing a plurality of light beams of different wavelengths (e.g. for optical fiber communications), and for forming spectrometers (e.g. correlation and scanning spectrometers). 14 figs.

  16. Diffraction by random Ronchi gratings.

    PubMed

    Torcal-Milla, Francisco Jose; Sanchez-Brea, Luis Miguel

    2016-08-01

    In this work, we obtain analytical expressions for the near-and far-field diffraction of random Ronchi diffraction gratings where the slits of the grating are randomly displaced around their periodical positions. We theoretically show that the effect of randomness in the position of the slits of the grating produces a decrease of the contrast and even disappearance of the self-images for high randomness level at the near field. On the other hand, it cancels high-order harmonics in far field, resulting in only a few central diffraction orders. Numerical simulations by means of the Rayleigh-Sommerfeld diffraction formula are performed in order to corroborate the analytical results. These results are of interest for industrial and technological applications where manufacture errors need to be considered. PMID:27505363

  17. Graded Achievement, Tested Achievement, and Validity

    ERIC Educational Resources Information Center

    Brookhart, Susan M.

    2015-01-01

    Twenty-eight studies of grades, over a century, were reviewed using the argument-based approach to validity suggested by Kane as a theoretical framework. The review draws conclusions about the meaning of graded achievement, its relation to tested achievement, and changes in the construct of graded achievement over time. "Graded…

  18. Fresnel diffraction by spherical obstacles

    NASA Technical Reports Server (NTRS)

    Hovenac, Edward A.

    1989-01-01

    Lommel functions were used to solve the Fresnel-Kirchhoff diffraction integral for the case of a spherical obstacle. Comparisons were made between Fresnel diffraction theory and Mie scattering theory. Fresnel theory is then compared to experimental data. Experiment and theory typically deviated from one another by less than 10 percent. A unique experimental setup using mercury spheres suspended in a viscous fluid significantly reduced optical noise. The major source of error was due to the Gaussian-shaped laser beam.

  19. Diffractive dijet production in CDF

    SciTech Connect

    Albrow, M.G.; CDF Collaboration

    1998-04-17

    We have studied events with a high-x{sub F} antiproton and two central jets in CDF, with p{anti p} collisions at {radical}s = 630 and 1800 GeV. These events are expected to be dominated by diffraction (pomeron exchange). The jet E{sub T} spectra are very similar to those of non-diffractively produced jets but slightly steeper; their azimuthal difference {Delta}{phi} is more peaked at 180{degree}.

  20. New CDF results on diffraction

    SciTech Connect

    Mesropian, Christina; /Rockefeller U.

    2006-12-01

    We report new diffraction results obtained by the CDF collaboration in proton-antiproton collisions at the Fermilab Tevatron collider at {radical}s=1.96 TeV. The first experimental evidence of exclusive dijet and diphoton production is presented. The exclusive results are discussed in context of the exclusive Higgs production at LHC. We also present the measurement of the Q{sup 2} and t dependence of the diffractive structure function.

  1. Defining Electron Backscatter Diffraction Resolution

    SciTech Connect

    El-Dasher, B S; Rollett, A D

    2005-02-07

    }{sub center} value is used to describe the overall system resolution, as it effectively quantifies the deviation of all orientations in the scan relative to the diffraction pattern least affected by distortions. The second is {omega}{sub max}, the largest misorientation angle possible between any pair of points in the dataset, and describes the worst possible case. Fig. 1 shows the effects of scan size and captured pattern resolution (bin size) on both angular values, illustrating that smaller scan and bin sizes have the effect of increasing angular resolution. However, it can be observed that the benefits of utilizing smaller bin sizes (and consequently slower data collection) diminish with scan size. Fig. 2 shows the effect of the number of pixels used in the Hough transform (defined as the ratio of pixels used to maximum possible pixels) on the angular values. It can be seen that the best angular resolutions are achieved at a pixel ratio of 0.80, again illustrating that the use of higher resolutions is not always beneficial. As evidenced by the results, the use of {omega}{sub center} and {omega}{sub max} not only permits the characterization of the angular resolution of an EBSD system, but they allow for a more efficient utilization of the system by identifying appropriate settings depending on the desired angular resolution [6].

  2. Atomic Resolution Coherent Diffractive Imaging and Ultrafast Science

    SciTech Connect

    Zuo, Jian-min

    2011-01-12

    A major scientific challenge is determining the 3-D atomic structure of small nanostructures, including single molecules. Coherent diffractive imaging (CDI) is a promising approach. Recent progress has demonstrated coherent diffraction patterns can be recorded from individual nanostructures and phased to reconstruct their structure. However, overcoming the dose limit imposed by radiation damage is a major obstacle toward the full potential of CDI. One approach is to use ultrafast x-ray or electron pulses. In electron diffraction, amplitudes recorded in a diffraction pattern are unperturbed by lens aberrations, defocus, and other microscope resolution-limiting factors. Sub-A signals are available beyond the information limit of direct imaging. Significant contrast improvement is obtained compared to high-resolution electron micrographs. progress has also been made in developing time-resolved electron diffraction and imaging for the study of ultrafast dynamic processes in materials. This talk will cover these crosscutting issues and the convergence of electron and x-ray diffraction techniques toward structure determination of single molecules.

  3. A 3-D numerical study of pinhole diffraction to predict the accuracy of EUV point diffraction interferometry

    SciTech Connect

    Goldberg, K.A. |; Tejnil, E.; Bokor, J. |

    1995-12-01

    A 3-D electromagnetic field simulation is used to model the propagation of extreme ultraviolet (EUV), 13-nm, light through sub-1500 {Angstrom} dia pinholes in a highly absorptive medium. Deviations of the diffracted wavefront phase from an ideal sphere are studied within 0.1 numerical aperture, to predict the accuracy of EUV point diffraction interferometersused in at-wavelength testing of nearly diffraction-limited EUV optical systems. Aberration magnitudes are studied for various 3-D pinhole models, including cylindrical and conical pinhole bores.

  4. Diffraction efficiency analysis for multi-level diffractive optical elements

    SciTech Connect

    Erteza, I.A.

    1995-11-01

    Passive optical components can be broken down into two main groups: Refractive elements and diffractive elements. With recent advances in manufacturing technologies, diffractive optical elements are becoming increasingly more prevalent in optical systems. It is therefore important to be able to understand and model the behavior of these elements. In this report, we present a thorough analysis of a completely general diffractive optical element (DOE). The main goal of the analysis is to understand the diffraction efficiency and power distribution of the various modes affected by the DOE. This is critical to understanding cross talk and power issues when these elements are used in actual systems. As mentioned, the model is based on a completely general scenario for a DOE. This allows the user to specify the details to model a wide variety of diffractive elements. The analysis is implemented straightforwardly in Mathematica. This report includes the development of the analysis, the Mathematica implementation of the model and several examples using the Mathematical analysis tool. It is intended that this tool be a building block for more specialized analyses.

  5. Novel diffraction gratings fabricated by means of plasma nanotechnologies

    NASA Astrophysics Data System (ADS)

    Ebizuka, N.; Sekine, Makoto; Ishikawa, K.; Kondo, H.; Hori, M.; Sasaki, M.; Bianco, A.; Maria Zerbi, F.; Hirahara, Y.; Aoki, W.

    2012-09-01

    A volume phase holographic grating (VPHG) achieves very high diffraction efficiency up to 100% for S or P polarized light at the first diffraction order. However, diffraction efficiency of the VPHG for non-polarized light becomes low according as Bragg angle becomes large, and bandwidth of diffraction efficiency becomes narrow according as refractive index modulation of grating lattice becomes small. A volume binary grating with rectangular lattice, consists of high and low refractive index media with large or small duty ratio, is able to achieve very high efficiency nearly 100% and a wide band width for both S and P polarization light. We have successfully fabricated germanium immersion gratings of step groove shape with resolving power of 45,000 at 10 micron by using a nano-precision 3D grinding machine and ELID (ELectrolytic In-process Dressing) method. However, the method requires a large amount of machine times and efforts. We had proposed a novel immersion grating with slot shape lattice of total reflection mirrors, which achieves high performance and lower fabrication cost. We describe the photolithography and the latest plasma nano-technologies for fabrications of the novel diffraction gratings in our presentation. We also introduce birefringence volume gratings in this article.

  6. Enhanced high-speed coherent diffraction imaging

    NASA Astrophysics Data System (ADS)

    Potier, Jonathan; Fricker, Sebastien; Idir, Mourad

    2011-03-01

    Due to recent advances in X-ray microscopy, we are now able to image objects with nanometer resolution thanks to Synchrotron beam lines or Free Electron Lasers (FEL). The PCI (Phase Contrast Imaging) is a robust technique that can recover the wavefront from measurements of only few intensity pictures in the Fresnel diffraction region. With our fast straightforward calculus methods, we manage to provide the phase induced by a microscopic specimen in few seconds. We can therefore obtain high contrasted images from transparent materials at very small scales. To reach atomic resolution imaging and thus make a transition from the near to the far field, the Coherent Diffraction Imaging (CDI) technique finds its roots in the analysis of diffraction patterns to obtain the phase of the altered complex wave. Theoretical results about existence and uniqueness of this retrieved piece of information by both iterative and direct algorithms have already been released. However, performances of algorithms remain limited by the coherence of the X-ray beam, presence of random noise and the saturation threshold of the detector. We will present reconstructions of samples using an enhanced version of HIO algorithm improving the speed of convergence and its repeatability. As a first step toward a practical X-Ray CDI system, initial images for reconstructions are acquired with the laser-based CDI system working in the visible spectrum.

  7. Scalar wave diffraction from a circular aperture

    SciTech Connect

    Cerjan, C.

    1995-01-25

    The scalar wave theory is used to evaluate the expected diffraction patterns from a circular aperture. The standard far-field Kirchhoff approximation is compared to the exact result expressed in terms of oblate spheroidal harmonics. Deviations from an expanding spherical wave are calculated for circular aperture radius and the incident beam wavelength using suggested values for a recently proposed point diffractin interferometer. The Kirchhoff approximation is increasingly reliable in the far-field limit as the aperture radius is increased, although significant errors in amplitude and phase persist.

  8. Sensitive visual test for concave diffraction gratings.

    NASA Technical Reports Server (NTRS)

    Bruner, E. C., Jr.

    1972-01-01

    A simple visual test for the evaluation of concave diffraction gratings is described. It is twice as sensitive as the Foucault knife edge test, from which it is derived, and has the advantage that the images are straight and free of astigmatism. It is particularly useful for grating with high ruling frequency where the above image faults limit the utility of the Foucault test. The test can be interpreted quantitatively and can detect zonal grating space errors of as little as 0.1 A.

  9. Diffraction described by virtual particle momentum exchange: the "diffraction force"

    NASA Astrophysics Data System (ADS)

    Mobley, Michael J.

    2011-09-01

    Particle diffraction can be described by an ensemble of particle paths determined through a Fourier analysis of a scattering lattice where the momentum exchange probabilities are defined at the location of scattering, not the point of detection. This description is compatible with optical wave theories and quantum particle models and provides deeper insights to the nature of quantum uncertainty. In this paper the Rayleigh-Sommerfeld and Fresnel-Kirchoff theories are analyzed for diffraction by a narrow slit and a straight edge to demonstrate the dependence of particle scattering on the distance of virtual particle exchange. The quantized momentum exchange is defined by the Heisenberg uncertainty principle and is consistent with the formalism of QED. This exchange of momentum manifests the "diffraction force" that appears to be a universal construct as it applies to neutral and charged particles. This analysis indicates virtual particles might form an exchange channel that bridges the space of momentum exchange.

  10. Secondary diffraction of diffracted Gaussian beam of laser radiation

    NASA Astrophysics Data System (ADS)

    Vasil'Ev, Yu. V.; Kozar', A. V.; Matyunin, A. V.

    2011-10-01

    The diffraction of a narrow Gaussian beam of laser radiation on mutually perpendicular edges of crossed, superimposed sharp wedge-shaped blades (safety razors) has been studied. The diffraction pattern observed on a flat screen behind the blades comprises a very bright central spot, which exhibits the structure of a "light network" with rectangular cells, and four groups of narrow bright bands that expand from the central spot toward the periphery and form a rectangular cross. The spatial frequency of light-field modulation on the screen can be controlled by varying the distance from the blades to screen.

  11. Electromagnetic diffraction efficiencies for plane reflection diffraction gratings

    NASA Technical Reports Server (NTRS)

    Marathay, A. S.; Shrode, T. E.

    1974-01-01

    The theory and computer programs, based on electromagnetic theory, for the analysis and design of echelle gratings were developed. The gratings are designed for instruments that operate in the ultraviolet portion of the spectrum. The theory was developed so that the resulting computer programs will be able to analyze deep (up to 30 wavelengths) gratings by including as many as 100 real or homogeneous diffraction orders. The program calculates the complex amplitude coefficient for each of the diffracted orders. A check on the numerical method used to solve the integral equations is provided by a conservation of energy calculation.

  12. Two-Diffraction-Order, Beam-Splitting, Imaging Spectrometer

    NASA Technical Reports Server (NTRS)

    Labaw, Clayton C.; Burns, Ronald N.

    1995-01-01

    Two-octave imaging spectrometer utilizes light of two harmonically related wavelengths diffracted to harmonically related orders at same angles, followed by separation via dichroic beam splitter before final imaging. Conceptual design of spectrometer calls for minimum number of optical elements to achieve coverage of required visible and near-infrared wavelengths in instrument of reduced size, weight, and cost.

  13. Ptychographic coherent x-ray diffractive imaging in the water window.

    PubMed

    Giewekemeyer, K; Beckers, M; Gorniak, T; Grunze, M; Salditt, T; Rosenhahn, A

    2011-01-17

    Coherent x-ray diffractive microscopy enables full reconstruction of the complex transmission function of an isolated object to diffraction-limited resolution without relying on any optical elements between the sample and detector. In combination with ptychography, also specimens of unlimited lateral extension can be imaged. Here we report on an application of ptychographic coherent diffractive imaging (PCDI) in the soft x-ray regime, more precisely in the so-called water window of photon energies where the high scattering contrast between carbon and oxygen is well-suited to image biological samples. In particular, we have reconstructed the complex sample transmission function of a fossil diatom at a photon energy of 517 eV. In imaging a lithographically fabricated test sample a resolution on the order of 50 nm (half-period length) has been achieved. Along with this proof-of-principle for PCDI at soft x-ray wavelengths, we discuss the experimental and technical challenges which can occur especially for soft x-ray PCDI. PMID:21263642

  14. Tilted femtosecond pulses for velocity matching in gas-phase ultrafast electron diffraction

    NASA Astrophysics Data System (ADS)

    Zhang, Ping; Yang, Jie; Centurion, Martin

    2014-08-01

    Recent advances in pulsed electron gun technology have resulted in femtosecond electron pulses becoming available for ultrafast electron diffraction experiments. For experiments investigating chemical dynamics in the gas phase, the resolution is still limited to picosecond time scales due to the velocity mismatch between laser and electron pulses. Tilted laser pulses can be used for velocity matching, but thus far this has not been demonstrated over an extended target in a diffraction setting. We demonstrate an optical configuration to deliver high-intensity laser pulses with a tilted pulse front for velocity matching over the typical length of a gas jet. A laser pulse is diffracted from a grating to introduce angular dispersion, and the grating surface is imaged on the target using large demagnification. The laser pulse duration and tilt angle were measured at and near the image plane using two different techniques: second harmonic cross correlation and an interferometric method. We found that a temporal resolution on the order of 100 fs can be achieved over a range of approximately 1 mm around the image plane.

  15. Diffractive optics for compact flat panel displays. Final report

    SciTech Connect

    Sweeney, D.; DeLong, K.

    1997-04-29

    Three years ago LLNL developed a practical method to dramatically reduce the chromatic aberration in single element diffractive imaging lenses. High efficiency, achromatic imaging lenses have been fabricated for human vision correction. This LDRD supported research in applying our new methods to develop a unique, diffraction-based optical interface with solid state, microelectronic imaging devices. Advances in microelectronics have led to smaller, more efficient components for optical systems. There have, however, been no equivalent advances in the imaging optics associated with these devices. The goal of this project was to replace the bulky, refractive optics in typical head-mounted displays with micro-thin diffractive optics to directly image flat-panel displays into the eye. To visualize the system think of the lenses of someone`s eyeglasses becoming flat-panel displays. To realize this embodiment, we needed to solve the problems of large chromatic aberrations and low efficiency that are associated with diffraction. We have developed a graceful tradeoff between chromatic aberrations and the diffractive optic thickness. It turns out that by doubling the thickness of a micro-thin diffractive lens we obtain nearly a two-times improvement in chromatic performance. Since the human eye will tolerate one diopter of chromatic aberration, we are able to achieve an achromatic image with a diffractive lens that is only 20 microns thick, versus 3 mm thickness for the comparable refractive lens. Molds for the diffractive lenses are diamond turned with sub-micron accuracy; the final lenses are cast from these molds using various polymers. We thus retain both the micro- thin nature of the diffractive optics and the achromatic image quality of refractive optics. During the first year of funding we successfully extended our earlier technology from 1 cm diameter optics required for vision applications up to the 5 cm diameter optics required for this application. 3 refs., 6 figs.

  16. Electron diffraction by plasmon waves

    NASA Astrophysics Data System (ADS)

    García de Abajo, F. J.; Barwick, B.; Carbone, F.

    2016-07-01

    An electron beam traversing a structured plasmonic field is shown to undergo diffraction with characteristic angular patterns of both elastic and inelastic outgoing electron components. In particular, a plasmonic grating (e.g., a standing wave formed by two counterpropagating plasmons in a thin film) produces diffraction orders of the same parity as the net number of exchanged plasmons. Large diffracted beam fractions are predicted to occur for realistic plasmon intensities in attainable geometries due to a combination of phase and amplitude changes locally imprinted on the passing electron wave. Our study opens vistas in the study of multiphoton exchanges between electron beams and evanescent optical fields with unexplored effects related to the transversal component of the electron wave function.

  17. Angle-resolved diffraction grating biosensor based on porous silicon

    NASA Astrophysics Data System (ADS)

    Lv, Changwu; Jia, Zhenhong; Liu, Yajun; Mo, Jiaqing; Li, Peng; Lv, Xiaoyi

    2016-03-01

    In this study, an optical biosensor based on a porous silicon composite structure was fabricated using a simple method. This structure consists of a thin, porous silicon surface diffraction grating and a one-dimensional porous silicon photonic crystal. An angle-resolved diffraction efficiency spectrum was obtained by measuring the diffraction efficiency at a range of incident angles. The angle-resolved diffraction efficiency of the 2nd and 3rd orders was studied experimentally and theoretically. The device was sensitive to the change of refractive index in the presence of a biomolecule indicated by the shift of the diffraction efficiency spectrum. The sensitivity of this sensor was investigated through use of an 8 base pair antifreeze protein DNA hybridization. The shifts of the angle-resolved diffraction efficiency spectrum showed a relationship with the change of the refractive index, and the detection limit of the biosensor reached 41.7 nM. This optical device is highly sensitive, inexpensive, and simple to fabricate. Using shifts in diffraction efficiency spectrum to detect biological molecules has not yet been explored, so this study establishes a foundation for future work.

  18. Boundary diffraction wave integrals for diffraction modeling of external occulters.

    PubMed

    Cady, Eric

    2012-07-01

    An occulter is a large diffracting screen which may be flown in conjunction with a telescope to image extrasolar planets. The edge is shaped to minimize the diffracted light in a region beyond the occulter, and a telescope may be placed in this dark shadow to view an extrasolar system with the starlight removed. Errors in position, orientation, and shape of the occulter will diffract additional light into this region, and a challenge of modeling an occulter system is to accurately and quickly model these effects. We present a fast method for the calculation of electric fields following an occulter, based on the concept of the boundary diffraction wave: the 2D structure of the occulter is reduced to a 1D edge integral which directly incorporates the occulter shape, and which can be easily adjusted to include changes in occulter position and shape, as well as the effects of sources-such as exoplanets-which arrive off-axis to the occulter. The structure of a typical implementation of the algorithm is included. PMID:22772218

  19. High throughput optoelectronic smart pixel systems using diffractive optics

    NASA Astrophysics Data System (ADS)

    Chen, Chih-Hao

    1999-12-01

    algorithm to design Diffractive Optical Elements (DOEs) having higher uniformity and better signal-to-noise ratio. The algorithm is based on nonlinear least-square optimization procedures and phase-shifting quantization scheme to minimize the reconstruction error of DOEs. We also describe a modified diffractive microlens design algorithm to overcome linewidth limitations in fabrication while achieving higher numerical aperture and better power efficiency. Several diffractive optical devices used in our smart pixel systems, including microlens arrays and spot array generators, are designed by these algorithms, and have been fabricated and characterized for system integration.

  20. Photoacoustic tomography: Ultrasonically beating optical diffusion and diffraction

    NASA Astrophysics Data System (ADS)

    Wang, Lihong

    2014-03-01

    A decade of research has pushed photoacoustic computed tomography to the forefront of molecular-level imaging, notes SPIE Fellow Lihong Wang (Washington University, St. Louis) in his plenary talk, "Photoacoustic Tomography: Ultrasonically Beating Optical Diffusion and Diffraction." Modern optical microscopy has resolution and diffraction limitations. But noninvasive functional photoacoustic computed tomography has overcome this limit, offering deep penetration with optical contrast and ultrasonic resolution of 1 cm depth or more -- up to 7 cm of penetration in some cases, such as evaluating sentinel lymph nodes for breast cancer staging. This opens up applications in whole body imaging, brain function, oxygen saturation, label-free cell analysis, and noninvasive cancer biopsies.

  1. Neutron diffraction on pulsed sources

    NASA Astrophysics Data System (ADS)

    Aksenov, V. L.; Balagurov, A. M.

    2016-03-01

    The current capabilities of and major scientific problems solved by time-of-flight neutron diffraction are reviewed. The reasons for the rapid development of the method over the last two decades have been mainly the emergence of third-generation pulsed sources with a megawatt time-averaged power and advances in neutron optical devices and detector systems. The paper discusses some historical aspects of time-of-flight neutron diffraction and examines the contribution to this method from F L Shapiro, the centennial of whose birth was celebrated in 2015. The state of the art with respect to neutron sources for studies on extracted beams is reviewed in a special section.

  2. High-pressure neutron diffraction

    SciTech Connect

    Xu, Hongwu

    2011-01-10

    This lecture will cover progress and prospect of applications of high-pressure neutron diffraction techniques to Earth and materials sciences. I will first introduce general high-pressure research topics and available in-situ high-pressure techniques. Then I'll talk about high-pressure neutron diffraction techniques using two types of pressure cells: fluid-driven and anvil-type cells. Lastly, I will give several case studies using these techniques, particularly, those on hydrogen-bearing materials and magnetic transitions.

  3. Diffraction encoded position measuring apparatus

    DOEpatents

    Tansey, Richard J.

    1991-01-01

    When a lightwave passes through a transmission grating, diffracted beams appear at the output or opposite side of the grating that are effectively Doppler shifted in frequency (phase) whereby a detector system can compare the phase of the zero order and higher order beams to obtain an indication of position. Multiple passes through the grating increase resolution for a given wavelength of a laser signal. The resolution can be improved further by using a smaller wavelength laser to generate the grating itself. Since the grating must only have a pitch sufficient to produce diffracted orders, inexpensive, ultraviolet wavelength lasers can be utilized and still obtain high resolution detection.

  4. Diffraction encoded position measuring apparatus

    DOEpatents

    Tansey, R.J.

    1991-09-24

    When a lightwave passes through a transmission grating, diffracted beams appear at the output or opposite side of the grating that are effectively Doppler shifted in frequency (phase) whereby a detector system can compare the phase of the zero order and higher order beams to obtain an indication of position. Multiple passes through the grating increase resolution for a given wavelength of a laser signal. The resolution can be improved further by using a smaller wavelength laser to generate the grating itself. Since the grating must only have a pitch sufficient to produce diffracted orders, inexpensive, ultraviolet wavelength lasers can be utilized and still obtain high resolution detection. 3 figures.

  5. Ellipsometry of diffractive insect reflectors

    NASA Astrophysics Data System (ADS)

    Brink, D. J.; Lee, M. E.

    1996-04-01

    Scales on the wings of certain insects, such as Trichoplusia orichalcea, exhibit a surface microstructure resembling a fine diffraction grating. Diffraction of incident light by this structure is responsible for many of the optical properties of the wings of this moth, such as the metallic yellow color and the almost-specular reflection and polarization properties of the scattered radiation. It is shown that by the use of null ellipsometry the polarization characteristics can be used to obtain the optical constants of the scale material. Theoretical considerations and suitable experimental conditions are discussed and evaluated.

  6. Subwavelength diffractive color beam combiner.

    PubMed

    Petrov, Nikolai I; Nikitin, Vladislav G; Danilov, Viktor A; Popov, Vladimir V; Usievich, Boris A

    2014-09-01

    A high-efficiency subwavelength diffractive beam combiner operating in a visible spectral range is designed, fabricated, and demonstrated. Such a device combines red, green, and blue color beams into one output light beam. Diffraction efficiencies of different types of gratings are calculated for various materials, incidence angles, and polarizations of light. It is shown that the plasmon resonance via a grating coupling occurs at the determined conditions. Subwavelength gratings with a period of 400 nm are fabricated and tested using laser and laser diode sources. PMID:25321371

  7. Diffraction model of a step-out transition

    SciTech Connect

    Chao, A.W.; Zimmermann, F.

    1996-06-01

    The diffraction model of a cavity, suggested by Lawson, Bane and Sands is generalized to a step out transition. Using this model, the high frequency impedance is calculated explicitly for the case that the transition step is small compared with the beam pipe radius. In the diffraction model for a small step out transition, the total energy is conserved, but, unlike the cavity case, the diffracted waves in the geometric shadow and the pipe region, in general, do not always carry equal energy. In the limit of small step sizes, the impedance derived from the diffraction model agrees with that found by Balakin, Novokhatsky and also Kheifets. This impedance can be used to compute the wake field of a round collimator whose half aperture is much larger than the bunch length, as existing in the SLC final focus.

  8. FEMTO SECOND ELECTRON BEAM DIFFRACTION USING A PHOTOCATHODE RF GUN.

    SciTech Connect

    WANG,X.J.WU,Z.IHEE,H.

    2003-05-12

    One of the 21st century scientific frontiers is to explore the molecule structure transition on the femtosecond time scale. X-ray free electron laser (XFEL) is one of the tools now under development for investigating femto-second structure transition. We are proposing an alternative technique--femto-second electron diffraction based on a photocathode RF gun. We will present a design of a kHz femto-seconds electron diffraction system based on a photocathode RF gun. Our simulation shows that, the photocathode RF gun can produce 100 fs (FWHM) electron bunch with millions electrons at about 2 MeV. This is at least one order of magnitude reduction in bunch length, and two orders of magnitude increase in number of electrons comparing to present time-resolved electron diffraction system. We will also discuss various issues and limitations related to MeV electron diffraction.

  9. An Analysis of High School Mathematics Achievement and English Language Arts Achievement as Predictors of Science Achievement

    ERIC Educational Resources Information Center

    Edwards, Anthony C.

    2012-01-01

    Science assessments require students to read and comprehend questions and to solve mathematical problems. The purpose of this study is to determine whether the following variables can be used to predict science achievement: English language arts achievement, mathematics achievement, socioeconomic status (SES), limited English proficiency (LEP)…

  10. Fresnel Diffraction for CTR Microbunching

    SciTech Connect

    Tikhoplav, R.; Knyazik, A.; Rosenzweig, J. B.; Andonian, G.

    2009-01-22

    Laser beams of high intensities are routinely used for IFEL experiments. Such beams can potentially destroy microbunching diagnostic tools such as coherent transition radiation foils due to their low damage thresholds. Near-field Fresnel diffraction scheme for termination of CO{sub 2} laser beam has been experimentally studied and is presented in this paper. Novel THz camera was utilized for such study.

  11. Resolution limits of ultrafast ultrasound localization microscopy.

    PubMed

    Desailly, Yann; Pierre, Juliette; Couture, Olivier; Tanter, Mickael

    2015-11-21

    As in other imaging methods based on waves, the resolution of ultrasound imaging is limited by the wavelength. However, the diffraction-limit can be overcome by super-localizing single events from isolated sources. In recent years, we developed plane-wave ultrasound allowing frame rates up to 20,000 fps. Ultrafast processes such as rapid movement or disruption of ultrasound contrast agents (UCA) can thus be monitored, providing us with distinct punctual sources that could be localized beyond the diffraction limit. We previously showed experimentally that resolutions beyond λ/10 can be reached in ultrafast ultrasound localization microscopy (uULM) using a 128 transducer matrix in reception. Higher resolutions are theoretically achievable and the aim of this study is to predict the maximum resolution in uULM with respect to acquisition parameters (frequency, transducer geometry, sampling electronics). The accuracy of uULM is the error on the localization of a bubble, considered a point-source in a homogeneous medium. The proposed model consists in two steps: determining the timing accuracy of the microbubble echo in radiofrequency data, then transferring this time accuracy into spatial accuracy. The simplified model predicts a maximum resolution of 40 μm for a 1.75 MHz transducer matrix composed of two rows of 64 elements. Experimental confirmation of the model was performed by flowing microbubbles within a 60 μm microfluidic channel and localizing their blinking under ultrafast imaging (500 Hz frame rate). The experimental resolution, determined as the standard deviation in the positioning of the microbubbles, was predicted within 6 μm (13%) of the theoretical values and followed the analytical relationship with respect to the number of elements and depth. Understanding the underlying physical principles determining the resolution of superlocalization will allow the optimization of the imaging setup for each organ. Ultimately, accuracies better than the size of

  12. Spatial resolution limits for synchrotron-based infrared spectromicroscopy

    SciTech Connect

    Levenson, Erika; Lerch, Philippe; Martin, Michael C.

    2007-10-15

    Detailed spatial resolution tests were performed on beamline 1.4.4 at the Advanced Light Source synchrotron facility in Berkeley, CA. The high-brightness synchrotron source is coupled at this beamline to a Thermo-Electron Continumum XL infrared microscope. Two types of resolution tests in both the mid-IR (using a KBr beamsplitter and an MCT-A* detector) and in the near-IR (using a CaF2 beamsplitter and an InGaAS detector) were performed and compared to a simple diffraction-limited spot size model. At the shorter wavelengths in the near-IR the experimental results begin to deviate from only diffraction-limited. The entire data set is fit using a combined diffraction-limit and demagnified electron beam source size model. This description experimentally verifies how the physical electron beam size of the synchrotron source demagnified to the sample stage on the endstation begins to dominate the focussed spot size and therefore spatial resolution at higher energies. We discuss how different facilities, beamlines, and microscopes will affect the achievable spatial resolution.

  13. Digital diffractive optics: Have diffractive optics entered mainstream industry yet?

    NASA Astrophysics Data System (ADS)

    Kress, Bernard; Hejmadi, Vic

    2010-05-01

    When a new technology is integrated into industry commodity products and consumer electronic devices, and sold worldwide in retail stores, it is usually understood that this technology has then entered the realm of mainstream technology and therefore mainstream industry. Such a leap however does not come cheap, as it has a double edge sword effect: first it becomes democratized and thus massively developed by numerous companies for various applications, but also it becomes a commodity, and thus gets under tremendous pressure to cut down its production and integration costs while not sacrificing to performance. We will show, based on numerous examples extracted from recent industry history, that the field of Diffractive Optics is about to undergo such a major transformation. Such a move has many impacts on all facets of digital diffractive optics technology, from the optical design houses to the micro-optics foundries (for both mastering and volume replication), to the final product integrators or contract manufacturers. The main causes of such a transformation are, as they have been for many other technologies in industry, successive technological bubbles which have carried and lifted up diffractive optics technology within the last decades. These various technological bubbles have been triggered either by real industry needs or by virtual investment hype. Both of these causes will be discussed in the paper. The adjective ""digital"" in "digital diffractive optics" does not refer only, as it is done in digital electronics, to the digital functionality of the element (digital signal processing), but rather to the digital way they are designed (by a digital computer) and fabricated (as wafer level optics using digital masking techniques). However, we can still trace a very strong similarity between the emergence of micro-electronics from analog electronics half a century ago, and the emergence of digital optics from conventional optics today.

  14. Diffraction Interference Induced Superfocusing in Nonlinear Talbot Effect

    PubMed Central

    Liu, Dongmei; Zhang, Yong; Wen, Jianming; Chen, Zhenhua; Wei, Dunzhao; Hu, Xiaopeng; Zhao, Gang; Zhu, S. N.; Xiao, Min

    2014-01-01

    We report a simple, novel subdiffraction method, i.e. diffraction interference induced superfocusing in second-harmonic (SH) Talbot effect, to achieve focusing size of less than λSH/4 (or λpump/8) without involving evanescent waves or subwavelength apertures. By tailoring point spread functions with Fresnel diffraction interference, we observe periodic SH subdiffracted spots over a hundred of micrometers away from the sample. Our demonstration is the first experimental realization of the Toraldo di Francia's proposal pioneered 62 years ago for superresolution imaging. PMID:25138077

  15. Gene transfer as a strategy to achieve permanent cardioprotection II: rAAV-mediated gene therapy with heme oxygenase-1 limits infarct size 1 year later without adverse functional consequences

    PubMed Central

    Li, Qianhong; Guo, Yiru; Ou, Qinghui; Wu, Wen-Jian; Chen, Ning; Zhu, Xiaoping; Tan, Wei; Yuan, Fangping; Dawn, Buddhadeb; Luo, Li; Hunt, Gregory N.

    2013-01-01

    Extensive evidence indicates that heme oxygenase-1 (HO-1) exerts potent cytoprotective effects in response to stress. Previous studies have shown that gene therapy with HO-1 protects against myocardial ischemia/reperfusion injury for up to 8 weeks after gene transfer. However, the long-term effects of HO-1 gene therapy on myocardial ischemic injury and function are unknown. To address this issue, we created a recombinant adeno-associated viral vector carrying the HO-1 gene (rAAV/HO-1) that enables long-lasting transgene expression. Mice received injections in the anterior LV wall of rAAV/LacZ (LacZ group) or rAAV/HO-1 (HO-1 group); 1 year later, they were subjected to a 30-min coronary occlusion (O) and 4 h of reperfusion (R). Cardiac HO-1 gene expression was confirmed at 1 month and 1 year after gene transfer by immunoblotting and immunohistochemistry analyses. In the HO-1 group, infarct size (% of risk region) was dramatically reduced at 1 year after gene transfer (11.2 ± 2.1%, n = 12, vs. 44.7 ± 3.6%, n = 8, in the LacZ group; P < 0.05). The infarct-sparing effects of HO-1 gene therapy at 1 year were as powerful as those observed 24 h after ischemic PC (six 4-min O/4-min R cycles) (15.0 ± 1.7%, n = 10). There were no appreciable changes in LV fractional shortening, LV ejection fraction, or LV end-diastolic or end-systolic diameter at 1 year after HO-1 gene transfer as compared to the age-matched controls or with the LacZ group. Histology showed no inflammation in the myocardium 1 year after rAAV/HO-1-mediated gene transfer. These results demonstrate, for the first time, that rAAV-mediated HO-1 gene transfer confers long-term (1 year), possibly permanent, cardioprotection without adverse functional consequences, providing proof of principle for the concept of achieving prophylactic cardioprotection (i.e., “immunization against infarction”). PMID:21785893

  16. Teaching Diffraction with Hands-On Optical Spectrometry

    ERIC Educational Resources Information Center

    Fischer, Robert

    2012-01-01

    Although the observation of optical spectra is common practice in physics classes, students are usually limited to a passive, qualitative observation of nice colours. This paper discusses a diffraction-based spectrometer that allows students to take quantitative measurements of spectral bands. Students can build it within minutes from generic…

  17. Photon diffractive dissociation in deep-inelastic scattering

    SciTech Connect

    Levin, E. ); Wuesthoff, M. )

    1994-10-01

    This paper is mainly devoted to the presentation and discussion of formulas for the cross section of photon diffractive dissociation. The calculations which we present in a very detailed way are based on perturbative QCD. We improve formulas which describe this process in the triple Regge limit where the square of the missing mass [ital M][sub [ital X

  18. Diffraction Analysis of Solar Coronagraphs

    NASA Astrophysics Data System (ADS)

    Rabin, Douglas M.; gong, qian

    2016-05-01

    The design of a solar coronagraph is predicated on controlling diffracted and scattered light using principles dating back to Bernard Lyot in the 1930’s. The existence of many successful ground- and space-based coronagraphs testifies to our ability to apply these principles in specific cases, but it is difficult to explore a significant range of design parameters because the calculations are tricky and time-consuming. Indeed, scattered light is so design-specific that ad hoc analysis is unavoidable once guidelines from experience are used to create a first-guess system of baffles and low-scatter surfaces. Here we describe a combination of analytic and computational approaches that has the potential to explore coronagraph design space somewhat more systematically with respect to diffracted light.

  19. Diffraction operators in paraxial approach

    NASA Astrophysics Data System (ADS)

    Lasso, William; Navas, Marianela; Añez, Liz; Urdaneta, Romer; Díaz, Leonardo; Torres, César O.

    2014-07-01

    Nowadays, research in the field of science education points to the creation of alternative ways of teaching contents encouraging the development of more elaborate reasoning, where a high degree of abstraction and generalization of scientific knowledge prevails. On that subject, this research shows a didactic alternative proposal for the construction of Fresnel and Fraunhoffer diffraction concepts applying the Fourier transform technique in the study of electromagnetic waves propagation in free space. Curvature transparency and Fourier sphere operators in paraxial approximation are used in order to make the usual laborious mathematical approach easier. The main result shows that the composition of optic metaxial operators results in the discovery of a simpler way out of the standard electromagnetic wave propagation in free space between a transmitter and a receptor separated from a given distance. This allows to state that the didactic proposal shown encourages the construction of Fresnel and Fraunhoffer diffraction concepts in a more effective and easier way than the traditional teaching.

  20. Ultra-broadband achromatic imaging with diffractive photon sieves

    PubMed Central

    Zhao, Xiaonan; Hu, Jingpei; Lin, Yu; Xu, Feng; Zhu, Xiaojun; Pu, Donglin; Chen, Linsen; Wang, Chinhua

    2016-01-01

    Diffractive optical elements suffer from large chromatic aberration due to the strong wavelength-dependent nature in diffraction phenomena, and therefore, diffractive elements can work only at a single designed wavelength, which significantly limits the applications of diffractive elements in imaging. Here, we report on a demonstration of a wavefront coded broadband achromatic imaging with diffractive photon sieves. The broadband diffraction imaging is implemented with a wavefront coded pinhole pattern that generates equal focusing power for a wide range of operating wavelength in a single thin-film element without complicated auxiliary optical system. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieves. Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm compared with 0.32 nm of the conventional one. Further demonstration of the achromatic imaging with a bandwidth of 300 nm is also performed with a wavefront coded photon sieves integrated with a refractive element. PMID:27328713

  1. Ultra-broadband achromatic imaging with diffractive photon sieves.

    PubMed

    Zhao, Xiaonan; Hu, Jingpei; Lin, Yu; Xu, Feng; Zhu, Xiaojun; Pu, Donglin; Chen, Linsen; Wang, Chinhua

    2016-01-01

    Diffractive optical elements suffer from large chromatic aberration due to the strong wavelength-dependent nature in diffraction phenomena, and therefore, diffractive elements can work only at a single designed wavelength, which significantly limits the applications of diffractive elements in imaging. Here, we report on a demonstration of a wavefront coded broadband achromatic imaging with diffractive photon sieves. The broadband diffraction imaging is implemented with a wavefront coded pinhole pattern that generates equal focusing power for a wide range of operating wavelength in a single thin-film element without complicated auxiliary optical system. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieves. Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm compared with 0.32 nm of the conventional one. Further demonstration of the achromatic imaging with a bandwidth of 300 nm is also performed with a wavefront coded photon sieves integrated with a refractive element. PMID:27328713

  2. X-ray diffraction analysis of residual stress in zirconia dental composites

    NASA Astrophysics Data System (ADS)

    Allahkarami, Masoud

    Dental restoration ceramic is a complex system to be characterized. Beside its essential biocompatibility, and pleasant appearance, it requires being mechanically strong in a catastrophic loading environment. Any design is restricted with geometry boundary and material property limits. Inspired by natural teeth, a multilayer ceramic is a smart way of achieving an enhanced restoration. Bi-layers of zirconia core covered by porcelain are known as one of the best multilayer restorations. Residual stresses may be introduced into a bi-layer dental ceramic restoration during its entire manufacturing process due to thermal expansion and elastic property mismatch. It is impossible to achieve a free of residual stresses bi-layer zirconia-porcelain restoration. The idea is to take the advantage of residual stress in design in such a way to prevent the crack initiation and progression. The hypothesis is a compressive residual stress at external contact surface would be enabling the restoration to endure a greater tensile stress. Optimizing the layers thickness, manufacturing process, and validating 3D simulations require development of new techniques of thickness, residual stresses and phase transformation measurement. In the present work, a combined mirco-tomography and finite element based method were adapted for thickness measurement. Two new 2D X-ray diffraction based techniques were adapted for phase transformation area mapping and combined phase transformation and residual stress measurement. Concerning the complex geometry of crown, an efficient method for X-ray diffraction data collection mapping on a given curved surface was developed. Finally a novel method for 3D dimensional x-ray diffraction data collection and visualization were introduced.

  3. Diffraction gratings for lighting applications

    NASA Astrophysics Data System (ADS)

    Cornelissen, Hugo J.; de Boer, Dick K. G.; Tukker, Teus

    2013-09-01

    Sub-micron diffraction gratings have been used for two LED illumination applications. One is to create a transparent see through luminaire which can be used to illuminate and read a paper document or e-book. A second is a light sensor that can be used in a feedback loop to control a multicolor LED lamp. Optical design and experimental proof-of-principle are presented.

  4. Industrial applications of neutron diffraction

    SciTech Connect

    Felcher, G.P.

    1989-01-01

    Neutron diffraction (or, to be more general, neutron scattering) is a most versatile and universal tool, which has been widely employed to probe the structure, the dynamics and the magnetism of condensed matter. Traditionally used for fundamental research in solid state physics, this technique more recently has been applied to problems of immediate industrial interest, as illustrated in examples covering the main fields of endeavour. 14 refs., 14 figs.

  5. Vorticity production in shock diffraction

    NASA Astrophysics Data System (ADS)

    Sun, M.; Takayama, K.

    2003-03-01

    The production of vorticity or circulation production in shock wave diffraction over sharp convex corners has been numerically simulated and quantified. The corner angle is varied from 5° to 180°. Total vorticity is represented by the circulation, which is evaluated by integrating the velocity along a path enclosing the perturbed region behind a diffracting shock wave. The increase of circulation in unit time, or the rate of circulation production, depends on the shock strength and wall angle if the effects of viscosity and heat conductivity are neglected. The rate of vorticity production is determined by using a solution-adaptive code, which solves the Euler equations. It is shown that the rate of vorticity production is independent of the computational mesh and numerical scheme by comparing solutions from two different codes. It is found that larger wall angles always enhance the vorticity production. The vorticity production increases sharply when the corner angle is varied from 15° to 45°. However, for corner angles over 90°, the rate of vorticity production hardly increases and reaches to a constant value. Strong shock waves produce vorticity faster in general, except when the slipstream originating from the shallow corner attaches to the downstream wall. It is found that the vorticity produced by the slipstream represents a large proportion of the total vorticity. The slipstream is therefore a more important source of vorticity than baroclinic effects in shock diffraction.

  6. Liquid crystal filled diffraction gratings

    NASA Astrophysics Data System (ADS)

    Jepsen, Mary Lou

    1997-12-01

    Liquid crystal technology is becoming increasingly important for flat displays in electronics, computers and TV. Most liquid crystal displays currently made have as their basic unit, two flat surfaces each coated with a transparent, conductive layer, between which a thin layer of liquid crystals is sandwiched. The work detailed in this dissertation is based on a modification of the basic liquid crystal unit and studies the properties of structures which consist of certain anisotropic liquid crystals confined between a flat substrate and a corrugated one, each substrate being transparent and having a thin trans-parent conductive coating. Without an applied electric field, the refractive indices of the liquid crystal and corrugated substrate do not match, and thus strong diffraction occurs. When an electric field is applied to the device, the liquid crystals are re-oriented so that the refractive indices now match, and the device behaves as a uniform slab of homogeneous material producing no diffraction. Rigorous coupled wave analysis was developed to design the ideal devices and analyze the performance of our experimental ones. 99% diffraction efficiencies in single wavelength polarized illumination are shown to be possible with this class of devices. The best device we fabricated showed a 62% distraction efficiency, as our fabrication process roughened the top surface of the device so that (≃30%) of the incident light was lost to scatter. Several new fabrication processes are proposed to eliminate this scatter problem, and that details of fabrication processes thus far attempted are outlined.

  7. Submicron X-ray diffraction

    SciTech Connect

    MacDowell, Alastair; Celestre, Richard; Tamura, Nobumichi; Spolenak, Ralph; Valek, Bryan; Brown, Walter; Bravman, John; Padmore, Howard; Batterman, Boris; Patel, Jamshed

    2000-08-17

    At the Advanced Light Source in Berkeley the authors have instrumented a beam line that is devoted exclusively to x-ray micro diffraction problems. By micro diffraction they mean those classes of problems in Physics and Materials Science that require x-ray beam sizes in the sub-micron range. The instrument is for instance, capable of probing a sub-micron size volume inside micron sized aluminum metal grains buried under a silicon dioxide insulating layer. The resulting Laue pattern is collected on a large area CCD detector and automatically indexed to yield the grain orientation and deviatoric (distortional) strain tensor of this sub-micron volume. A four-crystal monochromator is then inserted into the beam, which allows monochromatic light to illuminate the same part of the sample. Measurement of diffracted photon energy allows for the determination of d spacings. The combination of white and monochromatic beam measurements allow for the determination of the total strain/stress tensor (6 components) inside each sub-micron sized illuminated volume of the sample.

  8. Growing Larger Crystals for Neutron Diffraction

    NASA Technical Reports Server (NTRS)

    Pusey, Marc

    2003-01-01

    Obtaining crystals of suitable size and high quality has been a major bottleneck in macromolecular crystallography. With the advent of advanced X-ray sources and methods the question of size has rapidly dwindled, almost to the point where if one can see the crystal then it was big enough. Quality is another issue, and major national and commercial efforts were established to take advantage of the microgravity environment in an effort to obtain higher quality crystals. Studies of the macromolecule crystallization process were carried out in many labs in an effort to understand what affected the resultant crystal quality on Earth, and how microgravity improved the process. While technological improvements are resulting in a diminishing of the minimum crystal size required, neutron diffraction structural studies still require considerably larger crystals, by several orders of magnitude, than X-ray studies. From a crystal growth physics perspective there is no reason why these 'large' crystals cannot be obtained: the question is generally more one of supply than limitations mechanism. This talk will discuss our laboratory s current model for macromolecule crystal growth, with highlights pertaining to the growth of crystals suitable for neutron diffraction studies.

  9. LED color mixing with diffractive structures

    NASA Astrophysics Data System (ADS)

    Bonenberger, Theresa; Baumgart, Jörg; Wendel, Simon; Neumann, Cornelius

    2013-03-01

    Lighting solutions with colored LEDs provide many opportunities for illumination. One of these opportunities is to create a color tunable light source. In this way different kinds of white light (color temperature) as well as discrete colors may be realized. This opens the field for applications as mood lighting. But there is always a spatial separation of the distinct LEDs that might get converted into an angular separation by any collimating optics. This angular separation causes such problems like color fringes and colored shadows that cannot be accepted in most applications. Conventional methods to solve these problems include e.g. mixing rods or dichroic filters. A new approach is the use of the dispersive effect of a diffractive structure to compensate the angular separation of the different colors. In this contribution the potential and limitations of diffractive structures in LED color mixing applications are discussed. Ray tracing simulations were performed to analyze such important parameters like efficiency, color performance and the cross section of the color mixing optics. New means for the estimation of color mixing performance were developed. A software tool makes it possible to detect the color distribution within ray trace data and it provides a quality factor to estimate the color mixing performance. It can be shown that the spectral band width has a large influence on the mixing process. Ray tracing simulations are compared with results of an experimental setup such that both measured as well as simulated data is presented.

  10. Advanced X-ray diffractive optics

    NASA Astrophysics Data System (ADS)

    Vila-Comamala, J.; Jefimovs, K.; Pilvi, T.; Ritala, M.; Sarkar, S. S.; Solak, H. H.; Guzenko, V. A.; Stampanoni, M.; Marone, F.; Raabe, J.; Tzvetkov, G.; Fink, R. H.; Grolimund, D.; Borca, C. N.; Kaulich, B.; David, C.

    2009-09-01

    X-ray microscopy greatly benefits from the advances in x-ray optics. At the Paul Scherrer Institut, developments in x-ray diffractive optics include the manufacture and optimization of Fresnel zone plates (FZPs) and diffractive optical elements for both soft and hard x-ray regimes. In particular, we demonstrate here a novel method for the production of ultra-high resolution FZPs. This technique is based on the deposition of a zone plate material (iridium) onto the sidewalls of a prepatterned template structure (silicon) by atomic layer deposition. This approach overcomes the limitations due to electron-beam writing of dense patterns in FZP fabrication and provides a clear route to push the resolution into sub-10 nm regime. A FZP fabricated by this method was used to resolve test structures with 12 nm lines and spaces at the scanning transmission x-ray microscope of the PolLux beamline of the Swiss Light Source at 1.2 keV photon energy.

  11. Diffraction Gratings for High-Intensity Laser Applications

    SciTech Connect

    Britten, J

    2008-01-23

    The scattering of light into wavelength-dependent discrete directions (orders) by a device exhibiting a periodic modulation of a physical attribute on a spatial scale similar to the wavelength of light has been the subject of study for over 200 years. Such a device is called a diffraction grating. Practical applications of diffraction gratings, mainly for spectroscopy, have been around for over 100 years. The importance of diffraction gratings in spectroscopy for the measurement of myriad properties of matter can hardly be overestimated. Since the advent of coherent light sources (lasers) in the 1960's, applications of diffraction gratings in spectroscopy have further exploded. Lasers have opened a vast application space for gratings, and apace, gratings have enabled entirely new classes of laser systems. Excellent reviews of the history, fundamental properties, applications and manufacturing techniques of diffraction gratings up to the time of their publication can be found in the books by Hutley (1) and more recently Loewen and Popov (2). The limited scope of this chapter can hardly do justice to such a comprehensive subject, so the focus here will be narrowly limited to characteristics required for gratings suitable for high-power laser applications, and methods to fabricate them. A particular area of emphasis will be on maximally-efficient large-aperture gratings for short-pulse laser generation.

  12. Compatibility of a Diffractive Pupil and Coronagraphic Imaging

    NASA Technical Reports Server (NTRS)

    Bendek, Eduardo; Belikov, Rusian; Pluzhnyk, Yevgeniy; Guyon, Olivier

    2013-01-01

    Detection and characterization of exo-earths require direct-imaging techniques that can deliver contrast ratios of 10(exp 10) at 100 milliarc-seconds or smaller angular separation. At the same time, astrometric data is required to measure planet masses and can help detect planets and constrain their orbital parameters. To minimize costs, a single space mission can be designed using a high efficiency coronograph to perform direct imaging and a diffractive pupil to calibrate wide-field distortions to enable high precision astrometric measurements. This paper reports the testing of a diffractive pupil on the high-contrast test bed at the NASA Ames Research Center to assess the compatibility of using a diffractive pupil with coronographic imaging systems. No diffractive contamination was found within our detectability limit of 2x10(exp -7) contrast outside a region of 12lambda/D and 2.5x10(exp -6) within a region spanning from 2 to 12lambda/D. Morphology of the image features suggests that no contamination exists even beyond the detectability limit specified or at smaller working angles. In the case that diffractive contamination is found beyond these stated levels, active wavefront control would be able to mitigate its intensity to 10(exp -7) or better contrast.

  13. Comparing Science Achievement Constructs: Targeted and Achieved

    ERIC Educational Resources Information Center

    Ferrara, Steve; Duncan, Teresa

    2011-01-01

    This article illustrates how test specifications based solely on academic content standards, without attention to other cognitive skills and item response demands, can fall short of their targeted constructs. First, the authors inductively describe the science achievement construct represented by a statewide sixth-grade science proficiency test.…

  14. New approaches to nonlinear diffractive field propagation.

    PubMed

    Christopher, P T; Parker, K J

    1991-07-01

    In many domains of acoustic field propagation, such as medical ultrasound imaging, lithotripsy shock treatment, and underwater sonar, a realistic calculation of beam patterns requires treatment of the effects of diffraction from finite sources. Also, the mechanisms of loss and nonlinear effects within the medium are typically nonnegligible. The combination of diffraction, attenuation, and nonlinear effects has been treated by a number of formulations and numerical techniques. A novel model that incrementally propagates the field of baffled planar sources with substeps that account for the physics of diffraction, attenuation, and nonlinearity is presented. The model accounts for the effect of refraction and reflection (but not multiple reflections) in the case of propagation through multiple, parallel layers of fluid medium. An implementation of the model for axis symmetric sources has been developed. In one substep of the implementation, a new discrete Hankel transform is used with spatial transform techniques to propagate the field over a short distance with diffraction and attenuation. In the other substep, the temporal frequency domain solution to Burgers' equation is implemented to account for the nonlinear accretion and depletion of harmonics. This approach yields a computationally efficient procedure for calculating beam patterns from a baffled planar, axially symmetric source under conditions ranging from quasilinear through shock. The model is not restricted by the usual parabolic wave approximation and the field's directionality is explicitly accounted for at each point. Useage of a harmonic-limiting scheme allows the model to propagate some previously intractable high-intensity nonlinear fields. Results of the model are shown to be in excellent agreement with measurements performed on the nonlinear field of an unfocused 2.25-MHz piston source, even in the near field where the established parabolic wave approximation model fails. Next, the model is used to

  15. Varieties of Achievement Motivation.

    ERIC Educational Resources Information Center

    Kukla, Andre; Scher, Hal

    1986-01-01

    A recent article by Nicholls on achievement motivation is criticized on three points: (1) definitions of achievement motives are ambiguous; (2) behavioral consequences predicted do not follow from explicit theoretical assumptions; and (3) Nicholls's account of the relation between his theory and other achievement theories is factually incorrect.…

  16. Motivation and School Achievement.

    ERIC Educational Resources Information Center

    Maehr, Martin L.; Archer, Jennifer

    Addressing the question, "What can be done to promote school achievement?", this paper summarizes the literature on motivation relating to classroom achievement and school effectiveness. Particular attention is given to how values, ideology, and various cultural patterns impinge on classroom performance and serve to enhance motivation to achieve.…

  17. Mobility and Reading Achievement.

    ERIC Educational Resources Information Center

    Waters, Theresa Z.

    A study examined the effect of geographic mobility on elementary school students' achievement. Although such mobility, which requires students to make multiple moves among schools, can have a negative impact on academic achievement, the hypothesis for the study was that it was not a determining factor in reading achievement test scores. Subjects…

  18. PASS and Reading Achievement.

    ERIC Educational Resources Information Center

    Kirby, John R.

    Two studies examined the effectiveness of the PASS (Planning, Attention, Simultaneous, and Successive cognitive processes) theory of intelligence in predicting reading achievement scores of normally achieving children and distinguishing children with reading disabilities from normally achieving children. The first study dealt with predicting…

  19. Stratified Diffractive Optic Approach for Creating High Efficiency Gratings

    NASA Technical Reports Server (NTRS)

    Chambers, Diana M.; Nordin, Gregory P.

    1998-01-01

    Gratings with high efficiency in a single diffracted order can be realized with both volume holographic and diffractive optical elements. However, each method has limitations that restrict the applications in which they can be used. For example, high efficiency volume holographic gratings require an appropriate combination of thickness and permittivity modulation throughout the bulk of the material. Possible combinations of those two characteristics are limited by properties of currently available materials, thus restricting the range of applications for volume holographic gratings. Efficiency of a diffractive optic grating is dependent on its approximation of an ideal analog profile using discrete features. The size of constituent features and, consequently, the number that can be used within a required grating period restricts the applications in which diffractive optic gratings can be used. These limitations imply that there are applications which cannot be addressed by either technology. In this paper we propose to address a number of applications in this category with a new method of creating high efficiency gratings which we call stratified diffractive optic gratings. In this approach diffractive optic techniques are used to create an optical structure that emulates volume grating behavior. To illustrate the stratified diffractive optic grating concept we consider a specific application, a scanner for a space-based coherent wind lidar, with requirements that would be difficult to meet by either volume holographic or diffractive optic methods. The lidar instrument design specifies a transmissive scanner element with the input beam normally incident and the exiting beam deflected at a fixed angle from the optical axis. The element will be rotated about the optical axis to produce a conical scan pattern. The wavelength of the incident beam is 2.06 microns and the required deflection angle is 30 degrees, implying a grating period of approximately 4 microns

  20. Electron Backscatter Diffraction in Low Vacuum Conditions

    SciTech Connect

    El-Dasher, B S; Torres, S G

    2008-07-17

    Most current scanning electron microscopes (SEMs) have the ability to analyze samples in a low vacuum mode, whereby a partial pressure of water vapor is introduced into the SEM chamber, allowing the characterization of nonconductive samples without any special preparation. Although the presence of water vapor in the chamber degrades electron backscatter diffraction (EBSD) patterns, the potential of this setup for EBSD characterization of nonconductive samples is immense. In this chapter we discuss the requirements, advantages and limitations of low vacuum EBSD (LV-EBSD), and present how this technique can be applied to a two-phase ceramic composite as well as hydrated biominerals as specific examples of when LV-EBSD can be invaluable.

  1. Blood screening using diffraction phase cytometry

    NASA Astrophysics Data System (ADS)

    Mir, Mustafa; Ding, Huafeng; Wang, Zhuo; Reedy, Jason; Tangella, Krishnarao; Popescu, Gabriel

    2010-03-01

    Blood smear analysis has remained a crucial diagnostic tool for pathologists despite the advent of automatic analyzers such as flow cytometers and impedance counters. Though these current methods have proven to be indispensible tools for physicians and researchers alike, they provide limited information on the detailed morphology of individual cells, and merely alert the operator to manually examine a blood smear by raising flags when abnormalities are detected. We demonstrate an automatic interferometry-based smear analysis technique known as diffraction phase cytometry (DPC), which is capable of providing the same information on red blood cells as is provided by current clinical analyzers, while rendering additional, currently unavailable parameters on the 2-D and 3-D morphology of individual red blood cells. To validate the utility of our technique in a clinical setting, we present a comparison between tests generated from 32 patients by a state of the art clinical impedance counter and DPC.

  2. Quantitative metallography by electron backscattered diffraction.

    PubMed

    Humphreys

    1999-09-01

    Although electron backscattered diffraction (EBSD) in the scanning electron microscope is used mainly to investigate the relationship between local textures and microstructures, the technique has now developed to the stage where it requires serious consideration as a tool for routine quantitative characterization of microstructures. This paper examines the application of EBSD to the characterization of phase distributions, grain and subgrain structures and also textures. Comparisons are made with the standard methods of quantitative metallography and it is shown that in many cases EBSD can produce more accurate and detailed measurements than the standard methods and that the data may sometimes be obtained more rapidly. The factors which currently limit the use of EBSD for quantitative microstructural characterization, including the speed of data acquisition and the angular and spatial resolutions, are discussed, and future developments are considered. PMID:10460682

  3. Ultrafast electron diffraction optimized for studying structural dynamics in thin films and monolayers.

    PubMed

    Badali, D S; Gengler, R Y N; Miller, R J D

    2016-05-01

    A compact electron source specifically designed for time-resolved diffraction studies of free-standing thin films and monolayers is presented here. The sensitivity to thin samples is achieved by extending the established technique of ultrafast electron diffraction to the "medium" energy regime (1-10 kV). An extremely compact design, in combination with low bunch charges, allows for high quality diffraction in a lensless geometry. The measured and simulated characteristics of the experimental system reveal sub-picosecond temporal resolution, while demonstrating the ability to produce high quality diffraction patterns from atomically thin samples. PMID:27226978

  4. Ultrafast electron diffraction optimized for studying structural dynamics in thin films and monolayers

    PubMed Central

    Badali, D. S.; Gengler, R. Y. N.; Miller, R. J. D.

    2016-01-01

    A compact electron source specifically designed for time-resolved diffraction studies of free-standing thin films and monolayers is presented here. The sensitivity to thin samples is achieved by extending the established technique of ultrafast electron diffraction to the “medium” energy regime (1–10 kV). An extremely compact design, in combination with low bunch charges, allows for high quality diffraction in a lensless geometry. The measured and simulated characteristics of the experimental system reveal sub-picosecond temporal resolution, while demonstrating the ability to produce high quality diffraction patterns from atomically thin samples. PMID:27226978

  5. Coherent X-ray diffraction from collagenous soft tissues

    SciTech Connect

    Berenguer de la Cuesta, Felisa; Wenger, Marco P.E.; Bean, Richard J.; Bozec, Laurent; Horton, Michael A.; Robinson, Ian K.

    2009-09-11

    Coherent X-ray diffraction has been applied in the imaging of inorganic materials with great success. However, its application to biological specimens has been limited to some notable exceptions, due to the induced radiation damage and the extended nature of biological samples, the last limiting the application of most part of the phasing algorithms. X-ray ptychography, still under development, is a good candidate to overcome such difficulties and become a powerful imaging method for biology. We describe herein the feasibility of applying ptychography to the imaging of biological specimens, in particular collagen rich samples. We report here speckles in diffraction patterns from soft animal tissue, obtained with an optimized small angle X-ray setup that exploits the natural coherence of the beam. By phasing these patterns, dark field images of collagen within tendon, skin, bone, or cornea will eventually be obtained with a resolution of 60-70 nm. We present simulations of the contrast mechanism in collagen based on atomic force microscope images of the samples. Simulations confirmed the 'speckled' nature of the obtained diffraction patterns. Once inverted, the patterns will show the disposition and orientation of the fibers within the tissue, by enhancing the phase contrast between protein and no protein regions of the sample. Our work affords the application of the most innovative coherent X-ray diffraction tools to the study of biological specimens, and this approach will have a significant impact in biology and medicine because it overcomes many of the limits of current microscopy techniques.

  6. 50 years of fiber diffraction.

    PubMed

    Holmes, Kenneth C

    2010-05-01

    In 1955 Ken Holmes started working on tobacco mosaic virus (TMV) as a research student with Rosalind Franklin at Birkbeck College, London. Afterward he spent 18months as a post doc with Don Caspar and Carolyn Cohen at the Children's Hospital, Boston where he continued the work on TMV and also showed that the core of the thick filament of byssus retractor muscle from mussels is made of two-stranded alpha-helical coiled-coils. Returning to England he joined Aaron Klug's group at the newly founded Laboratory of Molecular Biology in Cambridge. Besides continuing the TMV studies, which were aimed at calculating the three-dimensional density map of the virus, he collaborated with Pringle's group in Oxford to show that two conformation of the myosin cross-bridge could be identified in insect flight muscle. In 1968 he opened the biophysics department at the Max Planck Institute for Medical Research in Heidelberg, Germany. With Gerd Rosenbaum he initiated the use of synchrotron radiation as a source for X-ray diffraction. In his lab the TMV structure was pushed to 4A resolution and showed how the RNA binds to the protein. With his co-workers he solved the structure of g-actin as a crystalline complex and then solved the structure of the f-actin filament by orientating the g-actin structure so as to give the f-actin fiber diffraction pattern. He was also able to solve the structure of the complex of actin with tropomyosin from fiber diffraction. PMID:20079849

  7. Coherent Diffractive Imaging at LCLS

    NASA Astrophysics Data System (ADS)

    Schulz, Joachim

    2010-03-01

    Soft x-ray FEL light sources produce ultrafast x-ray pulses with outstanding high peak brilliance. This might enable the structure determination of proteins that cannot be crystallized. The deposited energy would destroy the molecules completely, but owing to the short pulses the destruction will ideally only happen after the termination of the pulse. In order to address the many challenges that we face in attempting molecular diffraction, we have carried out experiments in coherent diffraction from protein nanocrystals at the Linac Coherent Light Source (LCLS) at SLAC. The periodicity of these objects gives us much higher scattering signals than uncrystallized proteins would. The crystals are filtered to sizes less than 2 micron, and delivered to the pulsed X-ray beam in a liquid jet. The effects of pulse duration and fluence on the high-resolution structure of the crystals have been studied. Diffraction patterns are recorded at a repetition rate of 30 Hz with pnCCD detectors. This allows us to take 108,000 images per hour. With 2-mega-pixel-detectors this gives a data-rate of more than 400 GB per hour. The automated sorting and evaluation of hundreds of thousands images is another challenge of this kind of experiments. Preliminary results will be presented on our first LCLS experiments. This work was carried out as part of a collaboration, for which Henry Chapman is the spokesperson. The collaboration consists of CFEL DESY, Arizona State University, SLAC, Uppsala University, LLNL, The University of Melbourne, LBNL, the Max Planck Institute for Medical Research, and the Max Planck Advanced Study Group (ASG) at the CFEL. The experiments were carried out using the CAMP apparatus, which was designed and built by the Max Planck ASG at CFEL. The LCLS is operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences.

  8. A diffractive mechanism of focusing.

    PubMed

    Case, W B; Sadurni, E; Schleich, W P

    2012-12-01

    We examine the free time evolution of a rectangular one dimensional Schrödinger wave packet of constant phase during the early stage which in the paraxial wave approximation is identical to the diffraction of a scalar field from a single slit. Our analysis, based on numerics and the Cornu spiral reveals considerable intricate detail behavior in the density and phase of the wave. We also point out a concentration of the intensity that occurs on axis and propose a new measure of width that expresses this concentration. PMID:23262675

  9. Fiber optic diffraction grating maker

    DOEpatents

    Deason, Vance A.; Ward, Michael B.

    1991-01-01

    A compact and portable diffraction grating maker comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent beam splitters, and collimating lenses or mirrors directing the split beam at an appropriate photosensitive material. The collimating optics, the output ends of the fiber optic coupler and the photosensitive plate holder are all mounted on an articulated framework so that the angle of intersection of the beams can be altered at will without disturbing the spatial filter, collimation or beam quality, and assuring that the beams will always intersect at the position of the plate.

  10. Fiber optic diffraction grating maker

    DOEpatents

    Deason, V.A.; Ward, M.B.

    1991-05-21

    A compact and portable diffraction grating maker is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent beam splitters, and collimating lenses or mirrors directing the split beam at an appropriate photosensitive material. The collimating optics, the output ends of the fiber optic coupler and the photosensitive plate holder are all mounted on an articulated framework so that the angle of intersection of the beams can be altered at will without disturbing the spatial filter, collimation or beam quality, and assuring that the beams will always intersect at the position of the plate. 4 figures.

  11. Nonlinear ptychographic coherent diffractive imaging.

    PubMed

    Odstrcil, M; Baksh, P; Gawith, C; Vrcelj, R; Frey, J G; Brocklesby, W S

    2016-09-01

    Ptychographic Coherent diffractive imaging (PCDI) is a significant advance in imaging allowing the measurement of the full electric field at a sample without use of any imaging optics. So far it has been confined solely to imaging of linear optical responses. In this paper we show that because of the coherence-preserving nature of nonlinear optical interactions, PCDI can be generalised to nonlinear optical imaging. We demonstrate second harmonic generation PCDI, directly revealing phase information about the nonlinear coefficients, and showing the general applicability of PCDI to nonlinear interactions. PMID:27607631

  12. Issues in Optical Diffraction Theory

    PubMed Central

    Mielenz, Klaus D.

    2009-01-01

    This paper focuses on unresolved or poorly documented issues pertaining to Fresnel’s scalar diffraction theory and its modifications. In Sec. 2 it is pointed out that all thermal sources used in practice are finite in size and errors can result from insufficient coherence of the optical field. A quarter-wave criterion is applied to show how such errors can be avoided by placing the source at a large distance from the aperture plane, and it is found that in many cases it may be necessary to use collimated light as on the source side of a Fraunhofer experiment. If these precautions are not taken the theory of partial coherence may have to be used for the computations. In Sec. 3 it is recalled that for near-zone computations the Kirchhoff or Rayleigh-Sommerfeld integrals are applicable, but fail to correctly describe the energy flux across the aperture plane because they are not continuously differentiable with respect to the assumed geometrical field on the source side. This is remedied by formulating an improved theory in which the field on either side of a semi-reflecting screen is expressed as the superposition of mutually incoherent components which propagate in the opposite directions of the incident and reflected light. These components are defined as linear combinations of the Rayleigh-Sommerfeld integrals, so that they are rigorous solutions of the wave equation as well as continuously differentiable in the aperture plane. Algorithms for using the new theory for computing the diffraction patterns of circular apertures and slits at arbitrary distances z from either side of the aperture (down to z = ± 0.0003 λ) are presented, and numerical examples of the results are given. These results show that the incident geometrical field is modulated by diffraction before it reaches the aperture plane while the reflected field is spilled into the dark space. At distances from the aperture which are large compared to the wavelength λ these field expressions are

  13. Novel cost-effective process for the replication of hybrid diffractive/refractive optical elements in silica glass

    SciTech Connect

    Maxey, L.C.; Nogues, J.L.; Moreshead, B.

    1998-08-01

    This CRADA between Martin Marietta Energy Systems, Inc. (Contractor) and GELTECH, Inc. (Participant) has demonstrated the feasibility of producing hybrid diffractive/refractive optics by a replication process which lends itself to high-volume, low-cost production. The program has built unpon unique capabilities of the Contractor and the Participant to achieve this demonstration. The Contractor has extensive experience and unique capabilities in the technology of single point diamong turning for optical components. The Participant has achieved unique success in the development of manufacturing processes for high-quality silica optical components using sol-gel technology. The merging of these two leading technologies has provided a synergism resulting in the demonstration of a manufacturing technology for cost-effective, high-volume production of silica glass precision hybrid optical components. Hybrid optical components are systems that integrate diffractive optical surfaces into lenses, resulting in designs that minimize the aberrations that degrade image quality without the need for additional glass elements. This reduces the cost, weight, and complexity of the system, while improving the overall optical efficiency. Previous applications of hybrid optical components have been primarily for infra-red applications, where diamond-turned germanium or silicon optics have been used. Hybrid optics for use in the visible have been limited to laboratory curiosities that were directly turned into plastic substrates. Through this CRADA the authors have achieved a manufacturing process for producing high quality silica glass hybrid lenses in an way that lends itself to mass production.

  14. Ultrafast electron diffraction from aligned molecules

    SciTech Connect

    Centurion, Martin

    2015-08-17

    The aim of this project was to record time-resolved electron diffraction patterns of aligned molecules and to reconstruct the 3D molecular structure. The molecules are aligned non-adiabatically using a femtosecond laser pulse. A femtosecond electron pulse then records a diffraction pattern while the molecules are aligned. The diffraction patterns are then be processed to obtain the molecular structure.

  15. Undergraduate Experiment with Fractal Diffraction Gratings

    ERIC Educational Resources Information Center

    Monsoriu, Juan A.; Furlan, Walter D.; Pons, Amparo; Barreiro, Juan C.; Gimenez, Marcos H.

    2011-01-01

    We present a simple diffraction experiment with fractal gratings based on the triadic Cantor set. Diffraction by fractals is proposed as a motivating strategy for students of optics in the potential applications of optical processing. Fraunhofer diffraction patterns are obtained using standard equipment present in most undergraduate physics…

  16. Linear systems approach to simulation of optical diffraction.

    PubMed

    Lambert, A J; Fraser, D

    1998-12-01

    The diffractive processes within an optical system can be simulated by computer to compute the diffraction-altered electric-field distribution at the output of the system from the electric-field distribution at the input. In the paraxial approximation the system can be described by an ABCD ray matrix whose elements in turn can be used to simplify the computation such that only a single computational step is required. We describe two rearrangements of such computations that allow the simulation to be expressed in a linear systems formulation, in particular using the fast-Fourier-transform algorithm. We investigate the sampling requirements for the kernel-modifying function or chirp that arises. We also use the special properties of the chirp to determine the spreading imposed by the diffraction. This knowledge can be used to reduce the computation if only a limited region of either the input or the output is of interest. PMID:18301681

  17. Diffraction imaging with electrons from an ultracold plasma source

    NASA Astrophysics Data System (ADS)

    Saliba, S. D.; Sheludko, D. V.; McCulloch, A. J.; Junker, M.; Bell, S. C.; Quiney, H. M.; Scholten, R. E.

    2010-03-01

    The molecular structure of biological molecules such as bacteriorhodopsin can be determined by electron diffraction, but general application has been limited by the brightness of conventional electron sources. Brightness is proportional to current and inversely proportional to electron temperature. A high brightness electron source from cold atom clouds presents a promising alternative to traditional high temperature (104 K) sources. Cold atoms in a MOT can be photoionized just above threshold, releasing electron bunches with temperatures as low as 10 K. Although the number of electrons that can be extracted from a MOT is relatively small, the reduced temperature may enable brightness competitive with conventional alternatives. We have simulated electron diffraction from electron microscopy grids and 2D arrays of simple molecules, exploring the energy, coherence and brightness requirements for practical diffraction imaging.

  18. Application of Electron Backscatter Diffraction to Phase Identification

    SciTech Connect

    El-Dasher, B S; Deal, A

    2008-07-16

    The identification of crystalline phases in solids requires knowledge of two microstructural properties: crystallographic structure and chemical composition. Traditionally, this has been accomplished using X-ray diffraction techniques where the measured crystallographic information, in combination with separate chemical composition measurements for specimens of unknown pedigrees, is used to deduce the unknown phases. With the latest microstructural analysis tools for scanning electron microscopes, both the crystallography and composition can be determined in a single analysis utilizing electron backscatter diffraction and energy dispersive spectroscopy, respectively. In this chapter, we discuss the approach required to perform these experiments, elucidate the benefits and limitations of this technique, and detail via case studies how composition, crystallography, and diffraction contrast can be used as phase discriminators.

  19. High pressure x-ray diffraction studies on nanocrystalline materials

    NASA Astrophysics Data System (ADS)

    Palosz, B.; Stel'makh, S.; Grzanka, E.; Gierlotka, S.; Pielaszek, R.; Bismayer, U.; Werner, S.; Palosz, W.

    2004-02-01

    Application of the in situ high pressure powder diffraction technique for examination of specific structural properties of nanocrystals based on the experimental data of SiC nanocrystalline powders of 2-30 nm in diameter is presented. Limitations and capabilities of the experimental techniques themselves and methods of diffraction data elaboration applied to nanocrystals with very small dimensions (<30 nm) are discussed. It is shown that a unique value of the lattice parameter cannot be determined for such small crystals using a standard powder diffraction experiment. It is also shown that, due to the complex structure constituting a two-phase, core/surface shell system, no unique compressibility coefficient can satisfactorily describe the behaviour of nanocrystalline powders under pressure. We offer a tentative interpretation of the distribution of macro- and micro-strains in nanoparticles of different grain size.

  20. Diffraction optics for terahertz waves

    NASA Astrophysics Data System (ADS)

    Wiltse, James C.

    2004-09-01

    Conventional lenses are important components for many terahertz applications, but ordinary lenses are very difficult to fabricate for short-focal lengths. Multi-level phase-corrected zoned lens antennas have been investigated with particular application at terahertz wavelengths. These zoned lenses (or diffractive optics) give better performance than ordinary lenses, and because of their planar construction are easier and cheaper to fabricate. The depths of cut needed for a grooved zone plate are quite small, even when materials with low dielectric constants are used. Zoned lenses have been built and tested at various frequencies from 100 GHz to 1.5 THz, with phase correction levels of half-wave, quarter-wave, or eighth-wavelength. The inherent losses in transparent materials increase monotonically over this frequency range. Typical low-loss materials include polystyrene, polyethylene, Teflon, polycarbonate, polystyrene foam, foamed polyethylene, low density polytetrafluoroethylene (PTFE), TPX, quartz, sapphire, and silicon. Low dielectric-constant materials are normally preferred to reduce reflection and attenuation losses. Techniques for cutting or milling the materials to small dimensions are important, because at 1.0 THz an eighth-wavelength correction for silicon is only 15 μm. Another characteristic of zoned diffraction optics is their frequency behavior. Previous investigations have considered their bandwidth dependence and quasi-periodic extended frequency response for a specified focal length. As frequency changes, the focal point moves along the axis of the zoned lens. An analysis is given to explain this effect.

  1. Simultaneous multicolor image formation with a single diffractive optical element.

    PubMed

    Levy, U; Marom, E; Mendlovic, D

    2001-08-01

    A design for a novel diffractive optical element (DOE) that can reconstruct three different intensity patterns when it is illuminated by three different wavelengths is presented. If the chosen wavelengths are red, green, and blue, full-color reconstruction capability is obtained. Reconstruction is achieved in the near field (Fresnel domain). Computer simulation results as well as experimental evidence are presented, proving the capabilities of this novel DOE design procedure. PMID:18049545

  2. A phase retrieval algorithm based on three-dimensionally translated diffraction patterns

    NASA Astrophysics Data System (ADS)

    Loetgering, L.; Hammoud, R.; Juschkin, L.; Wilhein, T.

    2015-09-01

    An iterative phase retrieval method is proposed that combines alternating projections and registration of three-dimensionally translated near-field diffraction patterns. This method allows to enhance resolution limited by a finite detector size and automatically stitches the assembled data while avoiding the need for a priori knowledge or scanning of the object as encountered in coherent diffraction imaging or ptychography.

  3. Action Learning in Action: Achieving Change with Limited Resources

    ERIC Educational Resources Information Center

    Grzybowski, Anne

    2008-01-01

    Implementing change is always difficult. It is even more difficult when change is not a priority for anyone else, individuals do not have the authority to tell people to "just do it" and they do not have the resources to "do it themselves". These are some of the challenges the Records Management Section at the University of Edinburgh faces, but it…

  4. Controlling open quantum systems: tools, achievements, and limitations

    NASA Astrophysics Data System (ADS)

    Koch, Christiane P.

    2016-06-01

    The advent of quantum devices, which exploit the two essential elements of quantum physics, coherence and entanglement, has sparked renewed interest in the control of open quantum systems. Successful implementations face the challenge of preserving relevant nonclassical features at the level of device operation. A major obstacle is decoherence, which is caused by interaction with the environment. Optimal control theory is a tool that can be used to identify control strategies in the presence of decoherence. Here we review recent advances in optimal control methodology that allow typical tasks in device operation for open quantum systems to be tackled and discuss examples of relaxation-optimized dynamics. Optimal control theory is also a useful tool to exploit the environment for control. We discuss examples and point out possible future extensions.

  5. Controlling open quantum systems: tools, achievements, and limitations.

    PubMed

    Koch, Christiane P

    2016-06-01

    The advent of quantum devices, which exploit the two essential elements of quantum physics, coherence and entanglement, has sparked renewed interest in the control of open quantum systems. Successful implementations face the challenge of preserving relevant nonclassical features at the level of device operation. A major obstacle is decoherence, which is caused by interaction with the environment. Optimal control theory is a tool that can be used to identify control strategies in the presence of decoherence. Here we review recent advances in optimal control methodology that allow typical tasks in device operation for open quantum systems to be tackled and discuss examples of relaxation-optimized dynamics. Optimal control theory is also a useful tool to exploit the environment for control. We discuss examples and point out possible future extensions. PMID:27143501

  6. Urinary proteomics in cardiovascular disease: Achievements, limits and hopes.

    PubMed

    Delles, Christian; Diez, Javier; Dominiczak, Anna F

    2011-06-01

    Cardiovascular disease (CVD) is the major cause of mortality and morbidity worldwide. Diagnosis of CVD and risk stratification of patients with CVD remains challenging despite the availability of a wealth of non-invasive and invasive tests. Clinical proteomics analyses a large number of peptides and proteins in biofluids. For clinical applications, the urinary proteome appears particularly attractive due to the relative low complexity compared with the plasma proteome and the noninvasive collection of urine. In this article, we review the results from pilot studies into urinary proteomics of coronary artery disease and discuss the potential of urinary proteomics in the context of pathogenesis of CVD. PMID:21523916

  7. The Longitudinal Effects of Achievement Goals and Perceived Control on University Student Achievement

    ERIC Educational Resources Information Center

    Daniels, Lia M.; Perry, Raymond P.; Stupnisky, Robert H.; Stewart, Tara L.; Newall, Nancy E. G.; Clifton, Rodney A.

    2014-01-01

    In the area of achievement motivation, students' beliefs pertaining to achievement goals and perceived control have separately guided a large amount theoretical and empirical research. However, limited research has considered the simultaneous effects of goals and control on achievement. The purpose of this study was to examine primary and…

  8. Array of reconfigurable diffractive lens on flexible substrate (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Moghimi, Mohammad J.; Jiang, Hongrui

    2016-03-01

    We designed and fabricated microscale lens arrays on a flexible substrate. The flexibility of the substrate allows for wide field of view imaging as well as optical focus scanning. Fresnel zone plates (FZPs), which are compact and lightweight, are used as microlenses for focusing. The arrangement of FZPs on flexible substrate can be reconfigured to maximize FOV. Tunable focus can also be achieved by stretching the FZPs laterally. In addition, the lightweight microlenses can be actuated to scan the focus axially. The lenses have a wide range of applications including displays, contact lenses, microscopy, surveillance and optical communications. The diameter of the microlenses ranges from 100 to 500 µm. The thickness of the lenses is 100 µm. Unlike refractive and reflective lenses, the focusing capability of FZPs is achieved via diffraction. FZPs consist of alternating black and white zones to modulate the phase of the incident light. The light diffracted from edge of the regions to achieve multiple focus. Most of the energy is diffracted into the first focus. The dark regions are made of silicon nanowires which are highly absorbent for visible spectrum. Standard processes, including wet and dry etching, are used to etch silicon substrate and form nanowires. The white zones are designed for both reflective and transmissive lenses. The lenses are implemented on PDMS as flexible substrate. The silicon nanowires are embedded into PDMS so that the shape of individual lens as well as the arrangement of the array can be reconfigured. In this article, we report our design, fabrication process and experiments.

  9. Future directions in high-pressure neutron diffraction

    NASA Astrophysics Data System (ADS)

    Guthrie, M.

    2015-04-01

    The ability to manipulate structure and properties using pressure has been well known for many centuries. Diffraction provides the unique ability to observe these structural changes in fine detail on lengthscales spanning atomic to nanometre dimensions. Amongst the broad suite of diffraction tools available today, neutrons provide unique capabilities of fundamental importance. However, to date, the growth of neutron diffraction under extremes of pressure has been limited by the weakness of available sources. In recent years, substantial government investments have led to the construction of a new generation of neutron sources while existing facilities have been revitalized by upgrades. The timely convergence of these bright facilities with new pressure-cell technologies suggests that the field of high-pressure (HP) neutron science is on the cusp of substantial growth. Here, the history of HP neutron research is examined with the hope of gleaning an accurate prediction of where some of these revolutionary capabilities will lead in the near future. In particular, a dramatic expansion of current pressure-temperature range is likely, with corresponding increased scope for extreme-conditions science with neutron diffraction. This increase in coverage will be matched with improvements in data quality. Furthermore, we can also expect broad new capabilities beyond diffraction, including in neutron imaging, small angle scattering and inelastic spectroscopy.

  10. Twenty Meter Space Telescope Based on Diffractive Fresnel Lens

    SciTech Connect

    Early, J; Hyde, R; Baron, R

    2003-06-26

    Diffractive lenses offer two potential advantages for very large aperture space telescopes; very loose surface-figure tolerances and physical implementation as thin, flat optical elements. In order to actually realize these advantages one must be able to build large diffractive lenses with adequate optical precision and also to compactly stow the lens for launch and then fully deploy it in space. We will discuss the recent fabrication and assembly demonstration of a 5m glass diffractive Fresnel lens at LLNL. Optical performance data from smaller full telescopes with diffractive lens and corrective optics show diffraction limited performance with broad bandwidths. A systems design for a 20m space telescope will be presented. The primary optic can be rolled to fit inside of the standard fairings of the Delta IV vehicle. This configuration has a simple deployment and requires no orbital assembly. A twenty meter visible telescope could have a significant impact in conventional astronomy with eight times the resolution of Hubble and over sixty times the light gathering capacity. If the light scattering is made acceptable, this telescope could also be used in the search for terrestrial planets.

  11. Cold neutron diffraction contrast tomography of polycrystalline material.

    PubMed

    Peetermans, S; King, A; Ludwig, W; Reischig, P; Lehmann, E H

    2014-11-21

    Traditional neutron imaging is based on the attenuation of a neutron beam through scattering and absorption upon traversing a sample of interest. It offers insight into the sample's material distribution at high spatial resolution in a non-destructive way. In this work, it is expanded to include the diffracted neutrons that were ignored so far and obtain a crystallographic distribution (grain mapping). Samples are rotated in a cold neutron beam of limited wavelength band. Projections of the crystallites formed by the neutrons they diffract are captured on a two dimensional imaging detector. Their positions on the detector reveal their orientation whereas the projections themselves are used to reconstruct the shape of the grains. Indebted to established synchrotron diffraction contrast tomography, this 'cold neutron diffraction contrast tomography' is performed on recrystallized aluminium for experimental comparison between both. Differences between set-up and method are discussed, followed by the application range in terms of sample properties (crystallite size and number, mosaicity and typical materials). Neutron diffraction contrast tomography allows to study large grains in bulky metallic structures. PMID:25274183

  12. Future directions in high-pressure neutron diffraction.

    PubMed

    Guthrie, M

    2015-04-22

    The ability to manipulate structure and properties using pressure has been well known for many centuries. Diffraction provides the unique ability to observe these structural changes in fine detail on lengthscales spanning atomic to nanometre dimensions. Amongst the broad suite of diffraction tools available today, neutrons provide unique capabilities of fundamental importance. However, to date, the growth of neutron diffraction under extremes of pressure has been limited by the weakness of available sources. In recent years, substantial government investments have led to the construction of a new generation of neutron sources while existing facilities have been revitalized by upgrades. The timely convergence of these bright facilities with new pressure-cell technologies suggests that the field of high-pressure (HP) neutron science is on the cusp of substantial growth. Here, the history of HP neutron research is examined with the hope of gleaning an accurate prediction of where some of these revolutionary capabilities will lead in the near future. In particular, a dramatic expansion of current pressure-temperature range is likely, with corresponding increased scope for extreme-conditions science with neutron diffraction. This increase in coverage will be matched with improvements in data quality. Furthermore, we can also expect broad new capabilities beyond diffraction, including in neutron imaging, small angle scattering and inelastic spectroscopy. PMID:25789450

  13. Polarized point diffraction interferometer for fringe stabilization

    NASA Astrophysics Data System (ADS)

    Kihm, Hagyong; Lee, Yun-Woo

    2010-08-01

    We propose a new point diffraction interferometer using a polarizer with a pinholed for qualitative optical analysis. Diffraction from a polarizer with a pinholed makes reference and measurement waves. Interference fringe between diffracted-undiffracted measurement wave and undiffracted-diffracted reference wave is stabilized by common-path configuration. We examined the pinhole size and divergence angle of the diffracted wave for test optics with various numerical aperture. Optical parts comprising the interferometer can be assembled into a small monolithic component and embedded into an imaging target for easy alignment. Optical systems evaluating imaging performances such as modulation transfer function would benefit in aligning target objects.

  14. Heritability of Creative Achievement

    ERIC Educational Resources Information Center

    Piffer, Davide; Hur, Yoon-Mi

    2014-01-01

    Although creative achievement is a subject of much attention to lay people, the origin of individual differences in creative accomplishments remain poorly understood. This study examined genetic and environmental influences on creative achievement in an adult sample of 338 twins (mean age = 26.3 years; SD = 6.6 years). Twins completed the Creative…

  15. Confronting the Achievement Gap

    ERIC Educational Resources Information Center

    Gardner, David

    2007-01-01

    This article talks about the large achievement gap between children of color and their white peers. The reasons for the achievement gap are varied. First, many urban minorities come from a background of poverty. One of the detrimental effects of growing up in poverty is receiving inadequate nourishment at a time when bodies and brains are rapidly…

  16. States Address Achievement Gaps.

    ERIC Educational Resources Information Center

    Christie, Kathy

    2002-01-01

    Summarizes 2 state initiatives to address the achievement gap: North Carolina's report by the Advisory Commission on Raising Achievement and Closing Gaps, containing an 11-point strategy, and Kentucky's legislation putting in place 10 specific processes. The North Carolina report is available at www.dpi.state.nc.us.closingthegap; Kentucky's…

  17. Wechsler Individual Achievement Test.

    ERIC Educational Resources Information Center

    Taylor, Ronald L.

    1999-01-01

    This article describes the Wechsler Individual Achievement Test, a comprehensive measure of achievement for individuals in grades K-12. Eight subtests assess mathematics reasoning, spelling, reading comprehension, numerical operations, listening comprehension, oral expression, and written expression. Its administration, standardization,…

  18. Inverting the Achievement Pyramid

    ERIC Educational Resources Information Center

    White-Hood, Marian; Shindel, Melissa

    2006-01-01

    Attempting to invert the pyramid to improve student achievement and increase all students' chances for success is not a new endeavor. For decades, educators have strategized, formed think tanks, and developed school improvement teams to find better ways to improve the achievement of all students. Currently, the No Child Left Behind Act (NCLB) is…

  19. Achievement Test Program.

    ERIC Educational Resources Information Center

    Ohio State Dept. of Education, Columbus. Trade and Industrial Education Service.

    The Ohio Trade and Industrial Education Achievement Test battery is comprised of seven basic achievement tests: Machine Trades, Automotive Mechanics, Basic Electricity, Basic Electronics, Mechanical Drafting, Printing, and Sheet Metal. The tests were developed by subject matter committees and specialists in testing and research. The Ohio Trade and…

  20. General Achievement Trends: Maryland

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…