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Sample records for interferometric images application

  1. Interferometric fiber optic sensors for biomedical applications of optoacoustic imaging.

    PubMed

    Lamela, Horacio; Gallego, Daniel; Gutierrez, Rebeca; Oraevsky, Alexander

    2011-03-01

    We present a non-metallic interferometric silica optical fiber ultrasonic wideband sensor for optoacoustic imaging applications. The ultrasonic sensitivity of this sensor has been characterized over the frequency range from 1 to 10 MHz. A comparative analysis has been carried out between this sensor and an array of piezoelectric transducers using optoacoustic signals generated from an optical absorbent embedded in a tissue mimicking phantom. Also, a two dimensional reconstructed image of the phantom using the fiber interferometric sensor is presented and compared to the image obtained using the Laser Optoacoustic Imaging System, LOIS-64B. The feasibility of our fiber optic based sensor for wideband ultrasonic detection is demonstrated. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Nonlinear interferometric vibrational imaging.

    PubMed

    Marks, Daniel L; Boppart, Stephen A

    2004-03-26

    Coherent anti-Stokes Raman scattering (CARS) processes are "coherent," but the phase of the anti-Stokes radiation is lost by most incoherent spectroscopic CARS measurements. We propose a Raman microscopy imaging method called nonlinear interferometric vibrational imaging, which measures Raman spectra by obtaining the temporal anti-Stokes signal through nonlinear interferometry. With a more complete knowledge of the anti-Stokes signal, we show through simulations that a high-resolution Raman spectrum can be obtained of a molecule in a single pulse using broad band radiation. This could be useful for identifying the three-dimensional spatial distribution of molecular species in tissue.

  3. 180-GHz Interferometric Imager

    NASA Technical Reports Server (NTRS)

    Kangaslahti, Pekka P.; Lim, Boon H.; O'Dwyer, Ian J.; Soria, Mary M.; Owen, Heather R.; Gaier, Todd C.; Lambrigtsen, Bjorn, H.; Tanner, Alan B.; Ruf, Christopher

    2011-01-01

    A 180-GHz interferometric imager uses compact receiver modules, combined high- and low-gain antennas, and ASIC (application specific integrated circuit) correlator technology, enabling continuous, all-weather observations of water vapor with 25-km resolution and 0.3-K noise in 15 minutes of observation for numerical weather forecasting and tropical storm prediction. The GeoSTAR-II prototype instrument is broken down into four major subsystems: the compact, low-noise receivers; sub-array modules; IF signal distribution; and the digitizer/correlator. Instead of the single row of antennas adopted in GeoSTAR, this version has four rows of antennas on a coarser grid. This dramatically improves the sensitivity in the desired field of view. The GeoSTAR-II instrument is a 48-element, synthetic, thinned aperture radiometer operating at 165-183 GHz. The instrument has compact receivers integrated into tiles of 16 elements in a 4x4 arrangement. These tiles become the building block of larger arrays. The tiles contain signal distribution for bias controls, IF signal, and local oscillator signals. The IF signals are digitized and correlated using an ASIC correlator to minimize power consumption. Previous synthetic aperture imagers have used comparatively large multichip modules, whereas this approach uses chip-scale modules mounted on circuit boards, which are in turn mounted on the distribution manifolds. This minimizes the number of connectors and reduces system mass. The use of ASIC technology in the digitizers and correlators leads to a power reduction close to an order of magnitude.

  4. Multiple Beam Correlation Using Single-Mode Fiber Optics with Application to Interferometric Imaging

    NASA Astrophysics Data System (ADS)

    Shaklan, Stuart Bruce

    A study of the application of single-mode fiber optics to the multiple-beam interferometric recombination problem is presented. In the laboratory, the fibers have been used in wide bandwidth, two-arm, Mach-Zehnder test interferometers as well as a 5-telescope imaging interferometer connected to an all-fiber beam combiner. Based upon these experiments and some theoretical studies it is shown that fiber optics and fiber optic components such as directional couplers provide an excellent alternative to conventional optics such as mirrors, beamsplitters, and relay lenses. The equations describing the measurement of the complex degree of coherence in an interferometer with a single-mode fiber in each arm are derived. The equations reveal an important feature of the fibers: they filter phase fluctuations due to aberrations and turbulence at the input and convert them to intensity fluctuations at the output. This leads to a simplification of the calibration of measured visibilities. The coupling efficiency of light which has passed through a turbulent atmosphere is also studied as a function of fiber parameters and turbulence conditions for both image motion stabilized and non-stabilized cases. For the former case, coupling efficiency remains greater than 50% as long as telescope diameter is no larger than the turbulence coherence length. Beam combination architectures using arrays of directional couplers are fully discussed. Arrays accommodating up to 20 input beams are presented. The arrays require only N detector pixels for N input beams. A scheme of temporal multiplexing of the phase of each beam is used to identify individual fringe pairs. One possible scheme allows wide bandwidths even for large numbers of beams. A 5-telescope interferometer has been constructed and connected to an all-fiber beam combiner. Two extended objects were observed and reconstructed using standard radio astronomy VLBI software. The interferometer and beam combiner had good thermal and

  5. Registration of interferometric SAR images

    NASA Technical Reports Server (NTRS)

    Lin, Qian; Vesecky, John F.; Zebker, Howard A.

    1992-01-01

    Interferometric synthetic aperture radar (INSAR) is a new way of performing topography mapping. Among the factors critical to mapping accuracy is the registration of the complex SAR images from repeated orbits. A new algorithm for registering interferometric SAR images is presented. A new figure of merit, the average fluctuation function of the phase difference image, is proposed to evaluate the fringe pattern quality. The process of adjusting the registration parameters according to the fringe pattern quality is optimized through a downhill simplex minimization algorithm. The results of applying the proposed algorithm to register two pairs of Seasat SAR images with a short baseline (75 m) and a long baseline (500 m) are shown. It is found that the average fluctuation function is a very stable measure of fringe pattern quality allowing very accurate registration.

  6. Radio and optical interferometric imaging

    NASA Astrophysics Data System (ADS)

    Cornwell, Tim J.

    1992-11-01

    Since diffraction-limited imaging with a single aperture yields angular resolution approx. lambda/D, the attainment of high angular resolution with single apertures requires the construction of correspondingly large monolithic apertures, the whole surface of which must be figured to much less than a wavelength. At the longer wavelengths, it is impossible to build a sufficiently large single aperture: for example, at lambda 21 cm, arcsec resolution requires an aperture of diameter approx. 50 km. At the shorter wavelengths, the atmosphere imposes a natural limit in resolution of about one arcsec. However, another route is possible; that is, using synthetic apertures to image the sky. Synthetic apertures are now in use in many fields, e.g., radio interferometry, radar imaging, and magnetic-resonance imaging. Radio-interferometric techniques developed in radio astronomy over the past 40 years are now being applied to optical and IR astronomical imaging by a number of groups. Furthermore, the problem of figuring synthetic apertures is considerably simpler, and can be implemented in a computer: new 'self-calibration' techniques allow imaging even in the presence of phase errors due to the atmosphere.

  7. Radio and optical interferometric imaging

    NASA Technical Reports Server (NTRS)

    Cornwell, Tim J.

    1992-01-01

    Since diffraction-limited imaging with a single aperture yields angular resolution approx. lambda/D, the attainment of high angular resolution with single apertures requires the construction of correspondingly large monolithic apertures, the whole surface of which must be figured to much less than a wavelength. At the longer wavelengths, it is impossible to build a sufficiently large single aperture: for example, at lambda 21 cm, arcsec resolution requires an aperture of diameter approx. 50 km. At the shorter wavelengths, the atmosphere imposes a natural limit in resolution of about one arcsec. However, another route is possible; that is, using synthetic apertures to image the sky. Synthetic apertures are now in use in many fields, e.g., radio interferometry, radar imaging, and magnetic-resonance imaging. Radio-interferometric techniques developed in radio astronomy over the past 40 years are now being applied to optical and IR astronomical imaging by a number of groups. Furthermore, the problem of figuring synthetic apertures is considerably simpler, and can be implemented in a computer: new 'self-calibration' techniques allow imaging even in the presence of phase errors due to the atmosphere.

  8. Transient volcano deformation sources imaged with interferometric synthetic aperture radar: Application to Seguam Island, Alaska

    USGS Publications Warehouse

    Masterlark, Timothy; Lu, Zhong

    2004-01-01

    Thirty interferometric synthetic aperture radar (InSAR) images, spanning various intervals during 1992–2000, document coeruptive and posteruptive deformation of the 1992–1993 eruption on Seguam Island, Alaska. A procedure that combines standard damped least squares inverse methods and collective surfaces, identifies three dominant amorphous clusters of deformation point sources. Predictions generated from these three point source clusters account for both the spatial and temporal complexity of the deformation patterns of the InSAR data. Regularized time series of source strength attribute a distinctive transient behavior to each of the three source clusters. A model that combines magma influx, thermoelastic relaxation, poroelastic effects, and petrologic data accounts for the transient, interrelated behavior of the source clusters and the observed deformation. Basaltic magma pulses, which flow into a storage chamber residing in the lower crust, drive this deformational system. A portion of a magma pulse is injected into the upper crust and remains in storage during both coeruption and posteruption intervals. This injected magma degasses and the volatile products accumulate in a shallow poroelastic storage chamber. During the eruption, another portion of the magma pulse is transported directly to the surface via a conduit roughly centered beneath Pyre Peak on the west side of the island. A small amount of this magma remains in storage during the eruption, and posteruption thermoelastic contraction ensues. This model, made possible by the excellent spatial and temporal coverage of the InSAR data, reveals a relatively simple system of interrelated predictable processes driven by magma dynamics.

  9. Weighting interferometric data for direct imaging

    NASA Astrophysics Data System (ADS)

    Boone, Frédéric

    2013-08-01

    The new generation interferometric arrays such as the Atacama Large Millimeter/submillimeter Array (ALMA) are composed of a large number of telescopes and their configurations are optimized for Fourier plane (a.k.a. uv-plane) coverage. As a consequence, solving for the missing information in the uv-plane is becoming less critical and the imaging algorithms can be revisited. The situation is getting similar to that encountered with single filled aperture telescopes and it is becoming possible to make images in a direct way. In this article a new weighting method is introduced to obtain "pseudo-clean" images without using prior information to solve for the Fourier transform of the source. This method is similar but not equivalent to the successive application of robust weighting and tapering at different scales. The idea is to weight the data to compensate for the imperfect distribution of natural weights in the uv-plane. The price to pay for this direct imaging technique is that the final point spread function (PSF or beam) may not follow a simple analytical shape such as a Gaussian (but this is also the case in optical astronomy) and some sensitivity is lost (but this is the case with any imaging algorithm in interferometry). Two parameters are introduced to control the trade-off between imaging quality and sensitivity, namely a threshold parameter and a coupling parameter. This method is applied to simulated ALMA observations with 16, 32 and 50 antennas. As expected this method is found to be more efficient with more antennas and for more compact configurations because the uv-plane coverage is more complete. With 50 antennas in compact configuration it is possible to reduce the amplitude of the inner sidelobes (outer sidelobes) by a factor >6 (>2) compared to natural weighting for ~10 % loss in sensitivity, leading to sidelobes lower than 1.6 % of the main lobe peak value. With 16 antennas only, the method can still be used to reduce the inner sidelobes of a

  10. Integrated circuit tester using interferometric imaging

    SciTech Connect

    Donaldson, W.R.; Michaels, E.M.R.; Akowuah, K.

    1997-04-01

    An interferometric imaging technique can provide time-resolved diagnostics of semiconductor integrated circuits. The semiconductor device is placed in one arm of an interferometer and illuminated with a picosecond pulse from a sub-bandgap infrared laser. As the laser passes through the semiconductor, it samples local variations in the index of refraction. These variations are caused by a number of physical phenomena including dopants in the material such as those used to form device structures, heating due to the flow of electrical currents, and changes in carrier concentration due to injection. These variations have both static and dynamic components. The dynamic components are associated with the normal device operation and are the most interesting. To separate the components, the device is first imaged in a quiescent state, and then a second image is taken after the device enters a known voltage state. Differences between the two images determine where the local index of refraction has changed and by how much. A third image taken with the reference arm of the interferometer blocked, allows device structures to be associated with particular changes in the index of refraction. Activation of the voltage state is synchronized with the pulsed illumination source, and the time delay between the application of the voltage and the laser probe pulse allows us to take a series of images that map the time evolution of the interferogram. This technique offers an exciting new diagnostic for semiconductor integrated circuits. The technique is noninvasive and compatible with high-speed operation of integrated circuits. The picosecond resolution enables us to either characterize specific logic states or watch an individual device turn on. This imaging technique is sensitive to all of the index of refraction changes that can be associated with IC`s. These include heating due to current flowing through narrow wires and charge injection into the depletion region of a transistor.

  11. Near-field Interferometric Imaging of Lightning

    NASA Astrophysics Data System (ADS)

    Stock, M.; Wu, T.; Akiyama, Y.; Kawasaki, Z.; Ushio, T.

    2015-12-01

    In the past, lightning interferometric mapping systems assumed that a source is very far from the measurement location. The assumption greatly simplifies the mathematics needed to locate the source, but the resulting source positions are limited to two spatial dimensions (azimuth and elevation). For short baseline systems, this assumption is very good because the source is almost always much farther away than the diameter of the array, making three-dimensional location all but impossible. By removing the far-field assumption, if the array is large enough it is possible to locate the source in three spatial dimensions using purely interferometric techniques. The purely interferometric method is quite different from the more typical time-of-arrival method. Instead of measuring arrival times or time differences of the radiation arriving at each station, a volume is imaged over a some integration period and then searched for a source. It is not necessary to know that a source exists in the integration period for the interferometric imaging technique to produce a well defined solution. Interferometric imaging can locate sources buried in noise, can locate both continuous and impulsive emission, and is capable of locating multiple simultaneously radiating sources. If the waveforms are corrected for propagation delay to the search volume, the integration period can be made arbitrarily small (limited only by the frequencies being observed), allowing the progression of lightning to be examined in detail. Near-field interferometry works equally well on a wide range of different signal types, from the LF to VHF bands in radio, or even on acoustic emissions from lightning. Near-field imaging can be used to correct the angular locations of short baseline systems when a source is very close to the array, or to produce full three-dimensional maps of lightning with long baseline arrays. Presented here are preliminary results of applying near-field interferometric imaging to the

  12. The 2012 interferometric imaging beauty contest

    NASA Astrophysics Data System (ADS)

    Baron, Fabien; Cotton, William D.; Lawson, Peter R.; Ridgway, Steve T.; Aarnio, Alicia; Monnier, John D.; Hofmann, Karl-Heinz; Schertl, Dieter; Weigelt, Gerd; Thiébaut, Eric; Soulez, Férréol; Mary, David; Millour, Florentin; Vannier, Martin; Young, John; Elias, Nicholas M.; Schmitt, Henrique R.; Rengaswamy, Sridharan

    2012-07-01

    We present the results of the fifth Interferometric Imaging Beauty Contest. The contest consists in blind imaging of test data sets derived from model sources and distributed in the OIFITS format. Two scenarios of imaging with CHARA/MIRC-6T were offered for reconstruction: imaging a T Tauri disc and imaging a spotted red supergiant. There were eight different teams competing this time: Monnier with the software package MACIM; Hofmann, Schertl and Weigelt with IRS; Thiebaut and Soulez with MiRA ; Young with BSMEM; Mary and Vannier with MIROIRS; Millour and Vannier with independent BSMEM and MiRA entries; Rengaswamy with an original method; and Elias with the radio-astronomy package CASA. The contest model images, the data delivered to the contestants and the rules are described as well as the results of the image reconstruction obtained by each method. These results are discussed as well as the strengths and limitations of each algorithm.

  13. The 2014 interferometric imaging beauty contest

    NASA Astrophysics Data System (ADS)

    Monnier, John D.; Berger, Jean-Philippe; Le Bouquin, Jean-Baptiste; Tuthill, Peter G.; Wittkowski, Markus; Grellmann, Rebekka; Müller, André; Renganswany, Sridhar; Hummel, Christian; Hofmann, Karl-Heinz; Schertl, Dieter; Weigelt, Gerd; Young, John; Buscher, David; Sanchez-Bermudez, Joel; Alberdi, Antxon; Schoedel, Rainer; Köhler, Rainer; Soulez, Ferréol; Thiébaut, Éric; Kluska, Jacques; Malbet, Fabien; Duvert, Gilles; Kraus, Stefan; Kloppenborg, Brian K.; Baron, Fabien; de Wit, Willem-Jan; Rivinius, Thomas; Merand, Antoine

    2014-07-01

    Here we present the results of the 6th biennial optical interferometry imaging beauty contest. Taking advantage of a unique opportunity, the red supergiant VY CMa and the Mira variable R Car were observed in the astronomical H-band with three 4-telescope configurations of the VLTI-AT array using the PIONIER instrument. The community was invited to participate in the subsequent image reconstruction and interpretation phases of the project. Ten groups submitted entries to the beauty contest, and we found reasonable consistency between images obtained from independent workers using quite different algorithms. We also found that significant differences existed between the submitted images, much greater than in past beauty contests that were all based on simulated data. A novel crowd-sourcing" method allowed consensus median images to be constructed, filtering likely artifacts and retaining real features." We definitively detect strong spots on the surfaces of both stars as well as distinct circumstellar shells of emission (likely water/CO) around R Car. In a close contest, Joel Sanchez (IAA-CSIC/Spain) was named the winner of the 2014 interferometric imaging beauty contest. This process has shown that new comers" can use publicly-available imaging software to interpret VLTI/PIONIER imaging data, as long as sufficient observations are taken to have complete uv coverage { a luxury that is often missing. We urge proposers to request adequate observing nights to collect sufficient data for imaging and for time allocation committees to recognise the importance of uv coverage for reliable interpretation of interferometric data. We believe that the result of the proposed broad international project will contribute to inspiring trust in the image reconstruction processes in optical interferometry.

  14. Molecular histopathology by nonlinear interferometric vibrational imaging

    NASA Astrophysics Data System (ADS)

    Boppart, Stephen A.

    2011-07-01

    A rapid label-free approach for molecular histopathology is presented and reviewed. Broadband vibrational spectra are generated by nonlinear interferometric vibrational imaging (NIVI), a coherent anti-Stokes Raman scattering (CARS)- based technique that uses interferometry and signal processing approaches to acquire Raman-like profiles with suppression of the non-resonant background. This allows for the generation of images that provide contrast based on quantitative chemical composition with high spatial and spectral resolution. Algorithms are demonstrated for reducing the diagnostic spectral information into color-coded composite images for the rapid identification of chemical constituents in skin, as well as differentiating normal from abnormal tissue in a pre-clinical tumor model for human breast cancer. This technology and methodology could result in an alternative method to the traditional histological staining and subjective interpretation procedure currently used in the diagnosis of disease, and has the potential for future in vivo molecular histopathology.

  15. Digital Detection of Exosomes by Interferometric Imaging

    PubMed Central

    Daaboul, George G.; Gagni, Paola; Benussi, Luisa; Bettotti, Paolo; Ciani, Miriam; Cretich, Marina; Freedman, David S.; Ghidoni, Roberta; Ozkumur, Ayca Yalcin; Piotto, Chiara; Prosperi, Davide; Santini, Benedetta; Ünlü, M. Selim; Chiari, Marcella

    2016-01-01

    Exosomes, which are membranous nanovesicles, are actively released by cells and have been attributed to roles in cell-cell communication, cancer metastasis, and early disease diagnostics. The small size (30–100 nm) along with low refractive index contrast of exosomes makes direct characterization and phenotypical classification very difficult. In this work we present a method based on Single Particle Interferometric Reflectance Imaging Sensor (SP-IRIS) that allows multiplexed phenotyping and digital counting of various populations of individual exosomes (>50 nm) captured on a microarray-based solid phase chip. We demonstrate these characterization concepts using purified exosomes from a HEK 293 cell culture. As a demonstration of clinical utility, we characterize exosomes directly from human cerebrospinal fluid (hCSF). Our interferometric imaging method could capture, from a very small hCSF volume (20 uL), nanoparticles that have a size compatible with exosomes, using antibodies directed against tetraspanins. With this unprecedented capability, we foresee revolutionary implications in the clinical field with improvements in diagnosis and stratification of patients affected by different disorders. PMID:27853258

  16. Fresnel Interferometric Imager: ground-based prototype.

    PubMed

    Serre, Denis; Deba, Paul; Koechlin, Laurent

    2009-05-20

    The Fresnel Interferometric Imager is a space-based astronomical telescope project yielding milli-arcsecond angular resolution and high contrast images with loose manufacturing constraints. This optical concept involves diffractive focusing and formation flying: a first "primary optics" space module holds a large binary Fresnel array, and a second "focal module" holds optical elements and focal instruments that allow for chromatic dispersion correction. We have designed a reduced-size Fresnel Interferometric Imager prototype and made optical tests in our laboratory in order to validate the concept for future space missions. The primary module of this prototype consists of a square, 8 cm side, 23 m focal length Fresnel array. The focal module is composed of a diaphragmed small telescope used as "field lens," a small cophased diverging Fresnel zone lens that cancels the dispersion, and a detector. An additional module collimates the artificial targets of various shapes, sizes, and dynamic ranges to be imaged. We describe the experimental setup, different designs of the primary Fresnel array, and the cophased Fresnel zone lens that achieves rigorous chromatic correction. We give quantitative measurements of the diffraction limited performances and dynamic range on double sources. The tests have been performed in the visible domain, lambda = 400-700 nm. In addition, we present computer simulations of the prototype optics based on Fresnel propagation that corroborate the optical tests. This numerical tool has been used to simulate the large aperture Fresnel arrays that could be sent to space with diameters of 3 to 30 m, foreseen to operate from Lyman alpha (121 nm) to mid IR (25 microm).

  17. Nonlinear Interferometric Vibrational Imaging (NIVI) with Novel Optical Sources

    NASA Astrophysics Data System (ADS)

    Boppart, Stephen A.; King, Matthew D.; Liu, Yuan; Tu, Haohua; Gruebele, Martin

    Optical imaging is essential in medicine and in fundamental studies of biological systems. Although many existing imaging modalities can supply valuable information, not all are capable of label-free imaging with high-contrast and molecular specificity. The application of molecular or nanoparticle contrast agents may adversely influence the biological system under investigation. These substances also present ongoing concerns over toxicity or particle clearance, which must be properly addressed before their approval for in vivo human imaging. Hence there is an increasing appreciation for label-free imaging techniques. It is of primary importance to develop imaging techniques that can indiscriminately identify and quantify biochemical compositions to high degrees of sensitivity and specificity through only the intrinsic optical response of endogenous molecular species. The development and use of nonlinear interferometric vibrational imaging, which is based on the interferometric detection of optical signals from coherent anti-Stokes Raman scattering (CARS), along with novel optical sources, offers the potential for label-free molecular imaging.

  18. The 2016 interferometric imaging beauty contest

    NASA Astrophysics Data System (ADS)

    Sanchez-Bermudez, J.; Thiébaut, E.; Hofmann, K.-H.; Heininger, M.; Schertl, D.; Weigelt, G.; Millour, F.; Schutz, A.; Ferrari, A.; Vannier, M.; Mary, D.; Young, J.

    2016-08-01

    Image reconstruction in optical interferometry has gained considerable importance for astrophysical studies during the last decade. This has been mainly due to improvements in the imaging capabilities of existing interferometers and the expectation of new facilities in the coming years. However, despite the advances made so far, image synthesis in optical interferometry is still an open field of research. Since 2004, the community has organized a biennial contest to formally test the different methods and algorithms for image reconstruction. In 2016, we celebrated the 7th edition of the "Interferometric Imaging Beauty Contest". This initiative represented an open call to participate in the reconstruction of a selected set of simulated targets with a wavelength-dependent morphology as they could be observed by the 2nd generation of VLTI instruments. This contest represents a unique opportunity to benchmark, in a systematic way, the current advances and limitations in the field, as well as to discuss possible future approaches. In this contribution, we summarize: (a) the rules of the 2016 contest; (b) the different data sets used and the selection procedure; (c) the methods and results obtained by each one of the participants; and (d) the metric used to select the best reconstructed images. Finally, we named Karl-Heinz Hofmann and the group of the Max-Planck-Institut f ur Radioastronomie as winners of this edition of the contest.

  19. Present status and applications of Interferometric Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    Qiao, Shubo; Li, Jinling; Sun, Fuping; Bian, Shaofeng

    2003-03-01

    Interferometric Synthetic Aperture Radar (InSAR) is a newly developed space geodetic technique, which provides the three dimensional information of targets on the Earth by interferometric processing of the Single Look Complex Images (SLC-Image) of Synthetic Aperture Radar (SAR). Because of the outstanding characteristics in all-weather and 24-hour continuous surveying, as well as the ability to penetrate into some substances on the Earth, the latent application fields of InSAR are rather broad, which becomes one of the foci in Earth science study. Hereby the principles and general status of SAR and InSAR are briefly introduced. The limitations in the precision of the height determination of targets on the Earth by InSAR are analyzed. The applications of InSAR and the mutual relation for promotion between InSAR and astro-geodynamics study are highlighted discussed.

  20. Wideband Interferometric Sensing and Imaging Polarimetry

    NASA Technical Reports Server (NTRS)

    Verdi, James Salvatore; Kessler, Otto; Boerner, Wolfgang-Martin

    1996-01-01

    Wideband Interferometric Sensing and Imaging Polarimetry (WISIP) has become an important, indispensible tool in wide area military surveillance and global environmental monitoring of the terrestrial and planetary covers. It enables dynamic, real time optimal feature extraction of significant characteristics of desirable targets and/or target sections with simultaneous suppression of undesirable background clutter and propagation path speckle at hitherto unknown clarity and never before achieved quality. WISIP may be adopted to the detection, recognition, and identification (DRI) of any stationary, moving or vibrating targets or distributed scatterer segments versus arbitrary stationary, dynamical changing and/or moving geo-physical/ecological environments, provided the instantaneous 2x2 phasor and 4x4 power density matrices for forward propagation/backward scattering, respectively, can be measured with sufficient accuracy. For example, the DRI of stealthy, dynamically moving inhomogeneous volumetric scatter environments such as precipitation scatter, the ocean/sea/lake surface boundary layers, the littoral coastal surf zones, pack ice and snow or vegetative canopies, dry sands and soils, etc. can now be successfully realized. A comprehensive overview is presented on how these modern high resolution/precision, complete polarimetric co-registered signature sensing and imaging techniques, complemented by full integration of novel navigational electronic tools, such as DGPS, will advance electromagnetic vector wave sensing and imaging towards the limits of physical realization. Various examples utilizing the most recent image data take sets of airborne, space shuttle, and satellite imaging systems demonstrate the utility of WISIP.

  1. Optoacoustic imaging using fiber-optic interferometric sensors.

    PubMed

    Lamela, Horacio; Gallego, Daniel; Oraevsky, Alexander

    2009-12-01

    An interferometric sensor based on nonmetallic silica optical fiber is presented as an ultrasonic wideband transducer for optoacoustic imaging applications. We have characterized the sensitivity of the optical fiber sensor by detecting optoacoustic signals from an optically absorbing object embedded in a tissue-mimicking phantom and have compared the signals recorded with those detected from the same phantom using an array of piezoelectric transducers. The optical fiber sensor was also scanned along the phantom surface in order to reconstruct two-dimensional optoacoustic images of the phantom. These images have been compared with images obtained using the Laser Optoacoustic Imaging System, LOIS-64B, demonstrating the feasibility of our fiber-optic sensor as a wideband ultrasonic transducer.

  2. A novel lightweight Fizeau infrared interferometric imaging system

    NASA Astrophysics Data System (ADS)

    Hope, Douglas A.; Hart, Michael; Warner, Steve; Durney, Oli; Romeo, Robert

    2016-05-01

    Aperture synthesis imaging techniques using an interferometer provide a means to achieve imagery with spatial resolution equivalent to a conventional filled aperture telescope at a significantly reduced size, weight and cost, an important implication for air- and space-borne persistent observing platforms. These concepts have been realized in SIRII (Space-based IR-imaging interferometer), a new light-weight, compact SWIR and MWIR imaging interferometer designed for space-based surveillance. The sensor design is configured as a six-element Fizeau interferometer; it is scalable, light-weight, and uses structural components and main optics made of carbon fiber replicated polymer (CFRP) that are easy to fabricate and inexpensive. A three-element prototype of the SIRII imager has been constructed. The optics, detectors, and interferometric signal processing principles draw on experience developed in ground-based astronomical applications designed to yield the highest sensitivity and resolution with cost-effective optical solutions. SIRII is being designed for technical intelligence from geo-stationary orbit. It has an instantaneous 6 x 6 mrad FOV and the ability to rapidly scan a 6x6 deg FOV, with a minimal SNR. The interferometric design can be scaled to larger equivalent filled aperture, while minimizing weight and costs when compared to a filled aperture telescope with equivalent resolution. This scalability in SIRII allows it address a range of IR-imaging scenarios.

  3. Interferometric SAR imaging by transmitting stepped frequency chaotic noise signals

    NASA Astrophysics Data System (ADS)

    Zhang, Yunhua; Gu, Xiang; Zhai, Wenshuai; Dong, Xiao; Shi, Xiaojin; Kang, Xueyan

    2015-10-01

    Noise radar has been applied in many fields since it was proposed more than 50 years ago. However, it has not been applied to interferometric SAR imaging yet as far as we know. This paper introduces our recent work on interferometric noise radar. An interferometric SAR system was developed which can transmit both chirp signal and chaotic noise signal (CNS) at multiple carrier frequencies. An airborne experiment with this system by transmitting both signals was carried out, and the data were processed to show the capability of interferometric SAR imaging with CNS. The results shows that although the interferometric phase quality of CNS is degraded due to the signal to noise ratio (SNR) is lower compared with that of chirp signal, we still can get satisfied DEM after multi-looking processing. Another work of this paper is to apply compressed sensing (CS) theory to the interferometric SAR imaging with CNS. The CS theory states that if a signal is sparse, then it can be accurately reconstructed with much less sampled data than that regularly required according to Nyquist Sampling Theory. To form a structured random matrix, if the transmitted signal is of fixed waveform, then random subsampling is needed. However, if the transmitted signal is of random waveform, then only uniform subsampling is needed. This is another advantage of noise signal. Both the interferometric phase images and the DEMs by regular method and by CS method are processed with results compared. It is shown that the degradation of interferometric phases due to subsampling is larger than that of amplitude image.

  4. Terahertz interferometric synthetic aperture tomography for confocal imaging systems.

    PubMed

    Heimbeck, M S; Marks, D L; Brady, D; Everitt, H O

    2012-04-15

    Terahertz (THz) interferometric synthetic aperture tomography (TISAT) for confocal imaging within extended objects is demonstrated by combining attributes of synthetic aperture radar and optical coherence tomography. Algorithms recently devised for interferometric synthetic aperture microscopy are adapted to account for the diffraction-and defocusing-induced spatially varying THz beam width characteristic of narrow depth of focus, high-resolution confocal imaging. A frequency-swept two-dimensional TISAT confocal imaging instrument rapidly achieves in-focus, diffraction-limited resolution over a depth 12 times larger than the instrument's depth of focus in a manner that may be easily extended to three dimensions and greater depths.

  5. Optoacoustic fiber optic interferometric sensors for biomedical applications

    NASA Astrophysics Data System (ADS)

    Gallego, Daniel; Lamela, Horacio

    2011-06-01

    A non-metallic interferometric optical fiber ultrasonic wideband sensor is presented for optoacoustic imaging applications. The ultrasonic sensitivity of intrinsic fiber optic interferometric sensors depends strongly of the material which is composed of. We compare experimentally the acoustic sensitivity of two fiber optic sensors based on singlemode silica optical fiber and multimode graded-index perfluorinated polymer optical fiber, respectively. Both sensors are designed for detection of optoacoustic wave sources with frequencies in the range from 100 kHz to 5 MHz. These results are also compared with a PVDF ultra wideband sensor. We evaluated detection of real world optoacoustic signals, generated from an optically absorbing object embedded in a tissue mimicking phantom, between our silica optical fiber sensor and an array of piezoelectric transducers. Reconstructed two dimensional acoustic images of the phantom are presented and compared with images obtained with the Laser Optoacoustic Imaging System, LOIS-64B, demonstrating the feasibility of our fiber optic sensor as a wideband ultrasonic sensor.

  6. Automatic aircraft landing using interferometric inverse synthetic aperture radar imaging.

    PubMed

    Soumekh, M

    1996-01-01

    This paper presents an interferometric processing of an aircraft's monostatic and bistatic inverse synthetic aperture radar (ISAR) signatures for automatic landing. The aircraft's squint angle in this ISAR imaging problem is near 90 degrees . We show that this extreme squint angle does not pose any problem for the ISAR Fourier-based (wavefront) reconstruction algorithm. In fact, the aircraft can be imaged accurately, and without any erroneous shifts in the cross-range domain, within the imposed theoretical resolution. Moreover, the algorithm is accurate enough such that one can utilize the phase of the ISAR monostatic and bistatic measurements for interferometric processing. The resultant interferometric ISAR image is used to detect undesirable rotations in the aircraft's orientation.

  7. Interferometric particle sizing with overlapping images despite Moiré

    NASA Astrophysics Data System (ADS)

    Talbi, Mohamed; Brunel, Marc

    2017-10-01

    Interferometric particle imaging is investigated in the case of overlapping images and sub-sampling conditions. It is shown that particle size estimation of a pair of particles remains possible despite Moiré. Particle sizing can be achieved although the determination of the separation between both particles is no longer possible.

  8. PP and PS interferometric images of near-seafloor sediments

    USGS Publications Warehouse

    Haines, S.S.

    2011-01-01

    I present interferometric processing examples from an ocean-bottom cable OBC dataset collected at a water depth of 800 m in the Gulf of Mexico. Virtual source and receiver gathers created through cross-correlation of full wavefields show clear PP reflections and PS conversions from near-seafloor layers of interest. Virtual gathers from wavefield-separated data show improved PP and PS arrivals. PP and PS brute stacks from the wavefield-separated data compare favorably with images from a non-interferometric processing flow. ?? 2011 Society of Exploration Geophysicists.

  9. Code-modulated interferometric imaging system using phased arrays

    NASA Astrophysics Data System (ADS)

    Chauhan, Vikas; Greene, Kevin; Floyd, Brian

    2016-05-01

    Millimeter-wave (mm-wave) imaging provides compelling capabilities for security screening, navigation, and bio- medical applications. Traditional scanned or focal-plane mm-wave imagers are bulky and costly. In contrast, phased-array hardware developed for mass-market wireless communications and automotive radar promise to be extremely low cost. In this work, we present techniques which can allow low-cost phased-array receivers to be reconfigured or re-purposed as interferometric imagers, removing the need for custom hardware and thereby reducing cost. Since traditional phased arrays power combine incoming signals prior to digitization, orthogonal code-modulation is applied to each incoming signal using phase shifters within each front-end and two-bit codes. These code-modulated signals can then be combined and processed coherently through a shared hardware path. Once digitized, visibility functions can be recovered through squaring and code-demultiplexing operations. Pro- vided that codes are selected such that the product of two orthogonal codes is a third unique and orthogonal code, it is possible to demultiplex complex visibility functions directly. As such, the proposed system modulates incoming signals but demodulates desired correlations. In this work, we present the operation of the system, a validation of its operation using behavioral models of a traditional phased array, and a benchmarking of the code-modulated interferometer against traditional interferometer and focal-plane arrays.

  10. Computed Optical Interferometric Imaging: Methods, Achievements, and Challenges

    PubMed Central

    South, Fredrick A.; Liu, Yuan-Zhi; Carney, P. Scott; Boppart, Stephen A.

    2016-01-01

    Three-dimensional high-resolution optical imaging systems are generally restricted by the trade-off between resolution and depth-of-field as well as imperfections in the imaging system or sample. Computed optical interferometric imaging is able to overcome these longstanding limitations using methods such as interferometric synthetic aperture microscopy (ISAM) and computational adaptive optics (CAO) which manipulate the complex interferometric data. These techniques correct for limited depth-of-field and optical aberrations without the need for additional hardware. This paper aims to outline these computational methods, making them readily available to the research community. Achievements of the techniques will be highlighted, along with past and present challenges in implementing the techniques. Challenges such as phase instability and determination of the appropriate aberration correction have been largely overcome so that imaging of living tissues using ISAM and CAO is now possible. Computed imaging in optics is becoming a mature technology poised to make a significant impact in medicine and biology. PMID:27795663

  11. Practical Issues Related to the Interferometric Imaging of Geosats

    DTIC Science & Technology

    2014-09-01

    telescope in the interferometer, and how this influences the amount of light coupled into a fiber and the observed interferometric visibility amplitude. We...geostationary satellites, optical interferometry imaging, telescope arrays 1. INTRODUCTION A critical gap in the Space Situational Awareness capability is the...55 milli arcsec), equivalent to the resolving power of a 3.6 m telescope observing at 800 nm. In order to obtain high-resolution (∼10 cm) ground based

  12. Interferometric laser imaging for in-flight cloud droplet sizing

    NASA Astrophysics Data System (ADS)

    Dunker, Christina; Roloff, Christoph; Grassmann, Arne

    2016-12-01

    A non-intrusive particle sizing method with a high spatial distribution is used to estimate cloud droplet spectra during flight test campaigns. The interferometric laser imaging for droplet sizing (ILIDS) method derives particle diameters of transparent spheres by evaluating the out-of-focus image patterns. This sizing approach requires a polarized monochromatic light source, a camera including an objective lens with a slit aperture, a synchronization unit and a processing tool for data evaluation. These components are adapted to a flight test environment to enable the microphysical investigation of different cloud genera. The present work addresses the design and specifications of ILIDS system, flight test preparation and selected results obtained in the lower and middle troposphere. The research platform was a Dornier Do228-101 commuter aircraft at the DLR Flight Operation Center in Braunschweig. It was equipped with the required instrumentation including a high-energy laser as the light source. A comprehensive data set of around 71 800 ILIDS images was acquired over the course of five flights. The data evaluation of the characteristic ILIDS fringe patterns relies, among other things, on a relationship between the fringe spacing and the diameter of the particle. The simplest way to extract this information from a pattern is by fringe counting, which is not viable for such an extensive number of data. A brief contrasting comparison of evaluation methods based on frequency analysis by means of fast Fourier transform and on correlation methods such as minimum quadratic difference is used to encompass the limits and accuracy of the ILIDS method for such applications.

  13. Instrumentation for ice crystal characterization in laboratory using interferometric out-of-focus imaging

    NASA Astrophysics Data System (ADS)

    Brunel, M.; Demange, G.; Fromager, M.; Talbi, M.; Zapolsky, H.; Patte, R.; Aït Ameur, K.; Jacquot-Kielar, J.; Coetmellec, S.; Gréhan, G.; Quevreux, B.

    2017-08-01

    Airborne characterization of ice crystals has important applications. The extreme difficulty of realizing in situ tests requires the development of a complete instrumentation in the laboratory. Such an installation should enable design, development, test, and calibration of instruments in conditions as close as possible to real ones. We present a set of numerical and experimental tools that have been developed to realize ice crystal sensors based on interferometric particle imaging. The set of tools covers the development of complementary simulators for crystal growth and interferometric particle imaging predictions, experimental generation of "programmable" ice crystals, and instrumentation of a freezing column where different techniques as in-focus imaging, out-of-focus imaging, and digital in-line holography can be combined simultaneously for test and calibration.

  14. Dynamic measurements of flowing cells labeled by gold nanoparticles using full-field photothermal interferometric imaging

    NASA Astrophysics Data System (ADS)

    Turko, Nir A.; Roitshtain, Darina; Blum, Omry; Kemper, Björn; Shaked, Natan T.

    2017-06-01

    We present highly dynamic photothermal interferometric phase microscopy for quantitative, selective contrast imaging of live cells during flow. Gold nanoparticles can be biofunctionalized to bind to specific cells, and stimulated for local temperature increase due to plasmon resonance, causing a rapid change of the optical phase. These phase changes can be recorded by interferometric phase microscopy and analyzed to form an image of the binding sites of the nanoparticles in the cells, gaining molecular specificity. Since the nanoparticle excitation frequency might overlap with the sample dynamics frequencies, photothermal phase imaging was performed on stationary or slowly dynamic samples. Furthermore, the computational analysis of the photothermal signals is time consuming. This makes photothermal imaging unsuitable for applications requiring dynamic imaging or real-time analysis, such as analyzing and sorting cells during fast flow. To overcome these drawbacks, we utilized an external interferometric module and developed new algorithms, based on discrete Fourier transform variants, enabling fast analysis of photothermal signals in highly dynamic live cells. Due to the self-interference module, the cells are imaged with and without excitation in video-rate, effectively increasing signal-to-noise ratio. Our approach holds potential for using photothermal cell imaging and depletion in flow cytometry.

  15. Dynamic measurements of flowing cells labeled by gold nanoparticles using full-field photothermal interferometric imaging.

    PubMed

    Turko, Nir A; Roitshtain, Darina; Blum, Omry; Kemper, Björn; Shaked, Natan T

    2017-06-01

    We present highly dynamic photothermal interferometric phase microscopy for quantitative, selective contrast imaging of live cells during flow. Gold nanoparticles can be biofunctionalized to bind to specific cells, and stimulated for local temperature increase due to plasmon resonance, causing a rapid change of the optical phase. These phase changes can be recorded by interferometric phase microscopy and analyzed to form an image of the binding sites of the nanoparticles in the cells, gaining molecular specificity. Since the nanoparticle excitation frequency might overlap with the sample dynamics frequencies, photothermal phase imaging was performed on stationary or slowly dynamic samples. Furthermore, the computational analysis of the photothermal signals is time consuming. This makes photothermal imaging unsuitable for applications requiring dynamic imaging or real-time analysis, such as analyzing and sorting cells during fast flow. To overcome these drawbacks, we utilized an external interferometric module and developed new algorithms, based on discrete Fourier transform variants, enabling fast analysis of photothermal signals in highly dynamic live cells. Due to the self-interference module, the cells are imaged with and without excitation in video-rate, effectively increasing signal-to-noise ratio. Our approach holds potential for using photothermal cell imaging and depletion in flow cytometry.

  16. Two microstrip arrays for interferometric SAR applications

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1993-01-01

    Two types of C-band aircraft interferometric Synthetic Aperture Radar (SAR) are being developed at JPL to measure the ocean wave characteristics. Each type requires two identical antennas with each having a long rectangular aperture to radiate fan-shaped beam(s). One type of these radars requires each of its antennas to radiate a broadside beam that will measure the target's cross-track velocity. The other type, having each of its antennas to radiate two off-broadside pointed beams, will allow the measurement of both the cross-track and the along-track velocities of the target. Because flush mounting of the antenna on the aircraft fuselage is desirable, microstrip patch array is selected for these interferometric SAR antennas. To meet the radar system requirement, each array needs a total of 76 microstrip patches which are arranged in a 38 x 2 rectangular aperture with a physical size of 1.6m x 16.5cm. To minimize the insertion loss and physical real estate of this relatively long array, a combined series/parallel feed technique is used. Techniques to suppress cross-pol radiation and to effectively utilize the RF power are also implemented. Cross-pol level of lower than -30 dB from the co-pol peak and low insertion loss of 0.36 dB have been achieved for both types of arrays. For the type of radar that requires two off-braodside pointed beams, a simple phasing technique is used to achieve this dual-beam capability with adequate antenna gain (20 dBi) and sidelobe level (-14 dB). Both radar arrays have been flight tested on aircraft with excellent antenna performance demonstrated.

  17. Interferometric Synthetic Aperture Microscopy: Computed Imaging for Scanned Coherent Microscopy

    PubMed Central

    Davis, Brynmor. J.; Marks, Daniel. L.; Ralston, Tyler. S.; Carney, P. Scott; Boppart, Stephen. A.

    2008-01-01

    Three-dimensional image formation in microscopy is greatly enhanced by the use of computed imaging techniques. In particular, Interferometric Synthetic Aperture Microscopy (ISAM) allows the removal of out-of-focus blur in broadband, coherent microscopy. Earlier methods, such as optical coherence tomography (OCT), utilize interferometric ranging, but do not apply computed imaging methods and therefore must scan the focal depth to acquire extended volumetric images. ISAM removes the need to scan the focus by allowing volumetric image reconstruction from data collected at a single focal depth. ISAM signal processing techniques are similar to the Fourier migration methods of seismology and the Fourier reconstruction methods of Synthetic Aperture Radar (SAR). In this article ISAM is described and the close ties between ISAM and SAR are explored. ISAM and a simple strip-map SAR system are placed in a common mathematical framework and compared to OCT and radar respectively. This article is intended to serve as a review of ISAM, and will be especially useful to readers with a background in SAR. PMID:20948975

  18. Interferometric Synthetic Aperture Microscopy: Computed Imaging for Scanned Coherent Microscopy.

    PubMed

    Davis, Brynmor J; Marks, Daniel L; Ralston, Tyler S; Carney, P Scott; Boppart, Stephen A

    2008-06-01

    Three-dimensional image formation in microscopy is greatly enhanced by the use of computed imaging techniques. In particular, Interferometric Synthetic Aperture Microscopy (ISAM) allows the removal of out-of-focus blur in broadband, coherent microscopy. Earlier methods, such as optical coherence tomography (OCT), utilize interferometric ranging, but do not apply computed imaging methods and therefore must scan the focal depth to acquire extended volumetric images. ISAM removes the need to scan the focus by allowing volumetric image reconstruction from data collected at a single focal depth. ISAM signal processing techniques are similar to the Fourier migration methods of seismology and the Fourier reconstruction methods of Synthetic Aperture Radar (SAR). In this article ISAM is described and the close ties between ISAM and SAR are explored. ISAM and a simple strip-map SAR system are placed in a common mathematical framework and compared to OCT and radar respectively. This article is intended to serve as a review of ISAM, and will be especially useful to readers with a background in SAR.

  19. Practical Issues Related to the Interferometric Imaging of Geosats

    NASA Astrophysics Data System (ADS)

    Schmitt, H.; Restaino, S.; Mozurkewich, D.; Mason, J.; Bock, K.; Dank, J.; Armstrong, J. T.; Baines, E.; Feller, G.

    2014-09-01

    Imaging geostationary satellites from the ground is an important Space Situational Awareness diagnostic tool that will require the use of optical interferometry. We developed a series of imaging and data quality simulations that allow us to investigate issues related to the interferometric imaging of such targets. We will discuss the number of baselines and sampling density needed to achieve different resolutions. We will also discuss some issues that are specific to the problem of imaging geosats, such as the size of the target relative to the resolving power of a single telescope in the interferometer, the precision needed in order to determine and correct for different sources of delay (atmospheric turbulence, telescope and target motion), and retrieve phase information from multiple baselines. The results presented here will be important to guide the design of future optical interferometers dedicated to the imaging of geosats.

  20. Interferometric system for precision imaging of vibrating structures

    NASA Technical Reports Server (NTRS)

    Gutierrez, Roman C. (Inventor); Shcheglov, Kirill V. (Inventor); Tang, Tony (Inventor)

    2001-01-01

    An optical profiler is modified in a way which allows it to image a MEMS device at various points during the movement of the MEMS device. The light source is synchronized with a desired movement of the MEMS device. The light source produces pulse at each synchronization period. During each pulse, an interferometric measurement is carried out. So long as the pulse is short enough such that the device does not move significantly, a detection of the position of the device can be accurately obtained.

  1. Molecular Histopathology by Spectrally Reconstructed Nonlinear Interferometric Vibrational Imaging

    PubMed Central

    Chowdary, Praveen D.; Jiang, Zhi; Chaney, Eric J.; Benalcazar, Wladimir A.; Marks, Daniel L.; Gruebele, Martin; Boppart, Stephen A.

    2011-01-01

    Sensitive assays for rapid quantitative analysis of histologic sections, resected tissue specimens, or in situ tissue are highly desired for early disease diagnosis. Stained histopathology is the gold standard but remains a subjective practice on processed tissue taking from hours to days. We describe a microscopy technique that obtains a sensitive and accurate color-coded image from intrinsic molecular markers. Spectrally reconstructed nonlinear interferometric vibrational imaging can differentiate cancer versus normal tissue sections with greater than 99% confidence interval in a preclinical rat breast cancer model and define cancer boundaries to ±100 μm with greater than 99% confidence interval, using fresh unstained tissue sections imaged in less than 5 minutes. By optimizing optical sources and beam delivery, this technique can potentially enable real-time point-of-care optical molecular imaging and diagnosis. PMID:21098699

  2. Interferometric and nonlinear-optical spectral-imaging techniques for outer space and live cells

    NASA Astrophysics Data System (ADS)

    Itoh, Kazuyoshi

    2015-12-01

    Multidimensional signals such as the spectral images allow us to have deeper insights into the natures of objects. In this paper the spectral imaging techniques that are based on optical interferometry and nonlinear optics are presented. The interferometric imaging technique is based on the unified theory of Van Cittert-Zernike and Wiener-Khintchine theorems and allows us to retrieve a spectral image of an object in the far zone from the 3D spatial coherence function. The retrieval principle is explained using a very simple object. The promising applications to space interferometers for astronomy that are currently in progress will also be briefly touched on. An interesting extension of interferometric spectral imaging is a 3D and spectral imaging technique that records 4D information of objects where the 3D and spectral information is retrieved from the cross-spectral density function of optical field. The 3D imaging is realized via the numerical inverse propagation of the cross-spectral density. A few techniques suggested recently are introduced. The nonlinear optical technique that utilizes stimulated Raman scattering (SRS) for spectral imaging of biomedical targets is presented lastly. The strong signals of SRS permit us to get vibrational information of molecules in the live cell or tissue in real time. The vibrational information of unstained or unlabeled molecules is crucial especially for medical applications. The 3D information due to the optical nonlinearity is also the attractive feature of SRS spectral microscopy.

  3. Low-cost interferometric TDM technology for dynamic sensing applications

    NASA Astrophysics Data System (ADS)

    Bush, Jeff; Cekorich, Allen

    2004-12-01

    A low-cost design approach for Time Division Multiplexed (TDM) fiber-optic interferometric interrogation of multi-channel sensor arrays is presented. This paper describes the evolutionary design process of the subject design. First, the requisite elements of interferometric interrogation are defined for a single channel sensor. The concept is then extended to multi-channel sensor interrogation implementing a TDM multiplex scheme where "traditional" design elements are utilized. The cost of the traditional TDM interrogator is investigated and concluded to be too high for entry into many markets. A new design approach is presented which significantly reduces the cost for TDM interrogation. This new approach, in accordance with the cost objectives, shows promise to bring this technology to within the threshold of commercial acceptance for a wide range of distributed fiber sensing applications.

  4. Comparison of interferometric spectral imaging techniques near the pupil plane and image plane

    NASA Astrophysics Data System (ADS)

    Itoh, Kazuyoshi; Inoue, Takashi; Ichioka, Yoshiki

    1990-07-01

    We present an analysis of signal to noise ratios of two interferometric techniques for spectral imaging and its experimental verification. One technique makes use of interference signals detected near the pupil plane and the other uses the signals near the image plane. The experiments showed that the latter technique is superior to the former under the normal conditions. 1.

  5. Hyperspectral imaging with in-line interferometric femtosecond stimulated Raman scattering spectroscopy

    NASA Astrophysics Data System (ADS)

    Dobner, Sven; Fallnich, Carsten

    2014-02-01

    We present the hyperspectral imaging capabilities of in-line interferometric femtosecond stimulated Raman scattering. The beneficial features of this method, namely, the improved signal-to-background ratio compared to other applicable broadband stimulated Raman scattering methods and the simple experimental implementation, allow for a rather fast acquisition of three-dimensional raster-scanned hyperspectral data-sets, which is shown for PMMA beads and a lipid droplet in water as a demonstration. A subsequent application of a principle component analysis displays the chemical selectivity of the method.

  6. Hyperspectral imaging with in-line interferometric femtosecond stimulated Raman scattering spectroscopy.

    PubMed

    Dobner, Sven; Fallnich, Carsten

    2014-02-28

    We present the hyperspectral imaging capabilities of in-line interferometric femtosecond stimulated Raman scattering. The beneficial features of this method, namely, the improved signal-to-background ratio compared to other applicable broadband stimulated Raman scattering methods and the simple experimental implementation, allow for a rather fast acquisition of three-dimensional raster-scanned hyperspectral data-sets, which is shown for PMMA beads and a lipid droplet in water as a demonstration. A subsequent application of a principle component analysis displays the chemical selectivity of the method.

  7. Hierarchical model-based interferometric synthetic aperture radar image registration

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Huang, Haifeng; Dong, Zhen; Wu, Manqing

    2014-01-01

    With the rapid development of spaceborne interferometric synthetic aperture radar technology, classical image registration methods are incompetent for high-efficiency and high-accuracy masses of real data processing. Based on this fact, we propose a new method. This method consists of two steps: coarse registration that is realized by cross-correlation algorithm and fine registration that is realized by hierarchical model-based algorithm. Hierarchical model-based algorithm is a high-efficiency optimization algorithm. The key features of this algorithm are a global model that constrains the overall structure of the motion estimated, a local model that is used in the estimation process, and a coarse-to-fine refinement strategy. Experimental results from different kinds of simulated and real data have confirmed that the proposed method is very fast and has high accuracy. Comparing with a conventional cross-correlation method, the proposed method provides markedly improved performance.

  8. Fiber optic interferometric sensors for aerospace applications

    NASA Technical Reports Server (NTRS)

    Cho, Y. C.

    1994-01-01

    This paper addresses two fiber optic sensor development programs in the Photonics Laboratory, NASA Ames Research Center, one in progress and the other being initiated. The ongoing program involves development of advanced acoustic sensors for wind tunnel applications. The new undertaking involves development of a novel sensor technique for studies of aerodynamic transition from laminar to turbulent flow.

  9. Fiber optic interferometric sensors for aerospace applications

    NASA Technical Reports Server (NTRS)

    Cho, Y. C.

    1994-01-01

    This paper addresses two fiber optic sensor development programs in the Photonics Laboratory, NASA Ames Research Center, one in progress and the other being initiated. The ongoing program involves development of advanced acoustic sensors for wind tunnel applications. The new undertaking involves development of a novel sensor technique for studies of aerodynamic transition from laminar to turbulent flow.

  10. Sparse representations and convex optimization as tools for LOFAR radio interferometric imaging

    NASA Astrophysics Data System (ADS)

    Girard, J. N.; Garsden, H.; Starck, J. L.; Corbel, S.; Woiselle, A.; Tasse, C.; McKean, J. P.; Bobin, J.

    2015-08-01

    Compressed sensing theory is slowly making its way to solve more and more astronomical inverse problems. We address here the application of sparse representations, convex optimization and proximal theory to radio interferometric imaging. First, we expose the theory behind interferometric imaging, sparse representations and convex optimization, and second, we illustrate their application with numerical tests with SASIR, an implementation of the FISTA, a Forward-Backward splitting algorithm hosted in a LOFAR imager. Various tests have been conducted in Garsden et al., 2015. The main results are: i) an improved angular resolution (super resolution of a factor ≈ 2) with point sources as compared to CLEAN on the same data, ii) correct photometry measurements on a field of point sources at high dynamic range and iii) the imaging of extended sources with improved fidelity. SASIR provides better reconstructions (five time less residuals) of the extended emission as compared to CLEAN. With the advent of large radiotelescopes, there is scope for improving classical imaging methods with convex optimization methods combined with sparse representations.

  11. Improving the performance of interferometric imaging through the use of disturbance feedforward.

    PubMed

    Böhm, Michael; Glück, Martin; Keck, Alexander; Pott, Jörg-Uwe; Sawodny, Oliver

    2017-05-01

    In this paper, we present a disturbance compensation technique to improve the performance of interferometric imaging for extremely large ground-based telescopes, e.g., the Large Binocular Telescope (LBT), which serves as the application example in this contribution. The most significant disturbance sources at ground-based telescopes are wind-induced mechanical vibrations in the range of 8-60 Hz. Traditionally, their optical effect is eliminated by feedback systems, such as the adaptive optics control loop combined with a fringe tracking system within the interferometric instrument. In this paper, accelerometers are used to measure the vibrations. These measurements are used to estimate the motion of the mirrors, i.e., tip, tilt and piston, with a dynamic estimator. Additional delay compensation methods are presented to cancel sensor network delays and actuator input delays, improving the estimation result even more, particularly at higher frequencies. Because various instruments benefit from the implementation of telescope vibration mitigation, the estimator is implemented as a separate, independent software on the telescope, publishing the estimated values via multicast on the telescope's ethernet. Every client capable of using and correcting the estimated disturbances can subscribe and use these values in a feedforward for its compensation device, e.g., the deformable mirror, the piston mirror of LINC-NIRVANA, or the fast path length corrector of the Large Binocular Telescope Interferometer. This easy-to-use approach eventually leveraged the presented technology for interferometric use at the LBT and now significantly improves the sky coverage, performance, and operational robustness of interferometric imaging on a regular basis.

  12. Interferometric imaging of the 2011-2013 Campi Flegrei unrest

    NASA Astrophysics Data System (ADS)

    De Siena, Luca; Nakahara, Hisashi; Zaccarelli, Lucia; Sammarco, Carmelo; La Rocca, Mario; Bianco, Francesca

    2017-04-01

    After its 1983-84 seismic and deformation crisis, seismologists have recorded very low and clustered seismicity at Campi Flegrei caldera (Italy). Hence, noise interferometry imaging has become the only option to image the present volcano logical state of the volcano. Three-component noise data recorded before, during, and after Campi Flegrei last deformation and geochemical unrest (2011-2013) have thus been processed with up-to-date interferometric imaging workflow based on MSNoise. Noise anisotropy, which strongly affects measurements throughout the caldera at all frequencies, has been accounted for by self-correlation measurements and smoothed by phase weighted stacking and phase-match filtering. The final group-velocity maps show strong low-velocity anomalies at the location of the last Campi Flegrei eruption (1538 A.D.). The main low-velocity anomalies contour Solfatara volcano and follow geomorphological cross-faulting. The comparison with geophysical imaging results obtained during the last seismic unrest at the caldera suggest strong changes in the physical properties of the volcano, particularly in the area of major hydrogeological hazard.

  13. FURTHER EVALUATION OF BOOTSTRAP RESAMPLING AS A TOOL FOR RADIO-INTERFEROMETRIC IMAGING FIDELITY ASSESSMENT

    SciTech Connect

    Kemball, Athol; Mitra, Modhurita; Chiang, H.-F.

    2010-01-15

    We report on a broader evaluation of statistical bootstrap resampling methods as a tool for pixel-level calibration and imaging fidelity assessment in radio interferometry. Pixel-level imaging fidelity assessment is a challenging problem, important for the value it holds in robust scientific interpretation of interferometric images, enhancement of automated pipeline reduction systems needed to broaden the user community for these instruments, and understanding leading-edge direction-dependent calibration and imaging challenges for future telescopes such as the Square Kilometre Array. This new computational approach is now possible because of advances in statistical resampling for data with long-range dependence and the available performance of contemporary high-performance computing resources. We expand our earlier numerical evaluation to span a broader domain subset in simulated image fidelity and source brightness distribution morphologies. As before, we evaluate the statistical performance of the bootstrap resampling methods against direct Monte Carlo simulation. We find that both model-based and subsample bootstrap methods continue to show significant promise for the challenging problem of interferometric imaging fidelity assessment when evaluated over the broader domain subset. We report on their measured statistical performance and guidelines for their use and application in practice. We also examine the performance of the underlying polarization self-calibration algorithm used in this study over a range of parallactic angle coverage.

  14. Applications of interferometrically derived terrain slopes: Normalization of SAR backscatter and the interferometric correlation coefficient

    NASA Technical Reports Server (NTRS)

    Werner, Charles L.; Wegmueller, Urs; Small, David L.; Rosen, Paul A.

    1994-01-01

    Terrain slopes, which can be measured with Synthetic Aperture Radar (SAR) interferometry either from a height map or from the interferometric phase gradient, were used to calculate the local incidence angle and the correct pixel area. Both are required for correct thematic interpretation of SAR data. The interferometric correlation depends on the pixel area projected on a plane perpendicular to the look vector and requires correction for slope effects. Methods for normalization of the backscatter and interferometric correlation for ERS-1 SAR are presented.

  15. Interferometric synthetic aperture radar (InSAR) and its applications to study volcanoes, part 2: InSAR imaging of Alaskan Volcanoes

    USGS Publications Warehouse

    Lu, Zhong; Dzurisin, Daniel; Wicks, Charles W.; Power, John A.

    2006-01-01

    Interferometric synthetic aperture radar (InSAR) is a remote sensing technique which can measure ground surface deformation with sub-centimeter precision and spatial resolution in tens-of-meters over a large region. This paper summarizes our recent InSAR studies of Alaskan volcanoes, associated with both eruptive and non-eruptive activity. It shows that InSAR can improve our understanding of how the Alaskan volcanoes work and enhance our capability to predict future eruptions and the associated hazards. 

  16. PURIFY: a new approach to radio-interferometric imaging

    NASA Astrophysics Data System (ADS)

    Carrillo, R. E.; McEwen, J. D.; Wiaux, Y.

    2014-04-01

    In a recent paper series, the authors have promoted convex optimization algorithms for radio-interferometric imaging in the framework of compressed sensing, which leverages sparsity regularization priors for the associated inverse problem and defines a minimization problem for image reconstruction. This approach was shown, in theory and through simulations in a simple discrete visibility setting, to have the potential to outperform significantly CLEAN and its evolutions. In this work, we leverage the versatility of convex optimization in solving minimization problems to both handle realistic continuous visibilities and offer a highly parallelizable structure paving the way to significant acceleration of the reconstruction and high-dimensional data scalability. The new algorithmic structure promoted relies on the simultaneous-direction method of multipliers (SDMM) and contrasts with the current major-minor cycle structure of CLEAN and its evolutions, which in particular cannot handle the state-of-the-art minimization problems under consideration where neither the regularization term nor the data term are differentiable functions. We release a beta version of an SDMM-based imaging software written in C and dubbed PURIFY (http://basp-group.github.io/purify/) that handles various sparsity priors, including our recent average sparsity approach sparsity averaging reweighted analysis (SARA). We evaluate the performance of different priors through simulations in the continuous visibility setting, confirming the superiority of SARA.

  17. Application of Interferometric Radars to Planetary Geologic Studies

    NASA Technical Reports Server (NTRS)

    Mouginis-Mark, P. J.; Rosen, P.; Freeman, A.

    2005-01-01

    Radar interferometry is rapidly becoming one of the major applications of radar systems in Earth orbit. So far the 2000 flight of the Shuttle Radar Topographic Mission (SRTM) is the only dedicated U.S. radar to be flown for the collection of interferometric data, but enough has been learned from this mission and from the use of foreign partner radars (ERS-1/2, Radarsat, ENIVISAT and JERS-1) for the potential planetary applications of this technique to be identified. A recent workshop was organized by the Jet Propulsion Laboratory and the Southern California Earthquake Center (SCEC), and was held at Oxnard, CA, from October 20th - 22nd, 2004. At this meeting, the major interest was in terrestrial radar systems, but approx. 20 or the approx. 250 attendees also discussed potential applications of interferometric radar for the terrestrial planets. The primary foci were for the detection of planetary water, the search for active tectonism and volcanism and the improved topographic mapping. This abstract provides a summary of these planetary discussions at the Oxnard meeting.

  18. Digital micromirror device as programmable rough particle in interferometric particle imaging.

    PubMed

    Fromager, M; Aït Ameur, K; Brunel, M

    2017-04-20

    The 2D autocorrelation of the projection of an irregular rough particle can be estimated using the analysis of its interferometric out-of-focus image. We report the development of an experimental setup that creates speckle-like patterns generated by "programmable" rough particles of desired-shape. It should become an important tool for the development of new setups, configurations, and algorithms in interferometric particle imaging.

  19. Stacking of large interferometric data sets in the image- and uv-domain - a comparative study

    NASA Astrophysics Data System (ADS)

    Lindroos, L.; Knudsen, K. K.; Vlemmings, W.; Conway, J.; Martí-Vidal, I.

    2015-02-01

    We present a new algorithm for stacking radio interferometric data in the uv-domain. The performance of uv-stacking is compared to the stacking of fully imaged data using simulated Atacama Large Millimeter/submillimeter Array and the Karl G. Jansky Very Large Array (VLA) deep extragalactic surveys. We find that image- and uv-stacking produce similar results, however, uv-stacking is typically the more robust method. An advantage of the uv-stacking algorithm is the availability of uv-data post-stacking, which makes it possible to identify and remove problematic baselines. For deep VLA surveys uv-stacking yields a signal-to-noise ratio that is up to 20 per cent higher than image-stacking. Furthermore, we have investigated stacking of resolved sources with a simulated VLA data set where 1.5 arcsec (10-12 kpc at z ˜ 1-4) sources are stacked. We find that uv-stacking, where a model is fitted directly to the visibilities, significantly improves the accuracy and robustness of the size estimates. While scientific motivation for this work is studying faint, high-z galaxies, the algorithm analysed here would also be applicable in other fields of astronomy. Stacking of radio interferometric data is also expected to play a big role for future surveys with telescopes such as Low-Frequency Array and Square Kilometre Array.

  20. Time-resolved quantitative multiphase interferometric imaging of a highly focused ultrasound pulse

    SciTech Connect

    Souris, Fabien; Grucker, Jules; Dupont-Roc, Jacques; Jacquier, Philippe; Arvengas, Arnaud; Caupin, Frederic

    2010-11-01

    Interferometric imaging is a well-established method to image phase objects by mixing the image wavefront with a reference one on a CCD camera. It has also been applied to fast transient phenomena, mostly through the analysis of single interferograms. It is shown that, for repetitive phenomena, multiphase acquisition brings significant advantages. A 1MHz focused sound field emitted by a hemispherical piezotransducer in water is imaged as an example. Quantitative image analysis provides high resolution sound field profiles. Pressure at focus determined by this method agrees with measurements from a fiber-optic probe hydrophone. This confirms that multiphase interferometric imaging can indeed provide quantitative measurements.

  1. Calibration of Interferometric Envisat/ASAR Image Mode Products

    NASA Astrophysics Data System (ADS)

    Holzner, J.; Eineder, M.; Schättler, B.

    2003-03-01

    Interferometric data processing requires careful calibration and validation of the complex input products. Interferometric calibration comprises geometric and phase accuracy aspects. With respect to geometry, orbit and timing parameter have to be calibrated in order to allow accurate geo-coding and optimal processing of the interferometric products. Phase accuracy of the input complex products is an important prerequisite for the interferometric measurement technique. This paper describes methods for location accuracy determination and reports the preliminary results obtained during the ongoing calibration/ validation phase of ENVISAT/ASAR. The paper includes the first ENVISAT/ASAR interferogram over Berlin, Germany. It was obtained with DLR~@~Ys interferometric processor GENESIS. This interferogram is compared to the result from ERS-2 for the same season of year. In addition, for verification of timing parameters two methods are described in this paper. The conventional method relies on precisely known ground control points (transponders or corner reflectors) and compares predicted and measured position in the slant range co-ordinate system. The new method relies on the precisely known geometry of ERS and a strong target visible in the ERS and ENVISAT/ASAR data. This cross-calibration method only requires a coarse height estimate of the considered target. Both methods are used to derive preliminary results for the location accuracy of ENVISAT/ASAR.

  2. The ZpiM algorithm: a method for interferometric image reconstruction in SAR/SAS.

    PubMed

    Dias, José M B; Leitao, José M N

    2002-01-01

    This paper presents an effective algorithm for absolute phase (not simply modulo-2-pi) estimation from incomplete, noisy and modulo-2pi observations in interferometric aperture radar and sonar (InSAR/InSAS). The adopted framework is also representative of other applications such as optical interferometry, magnetic resonance imaging and diffraction tomography. The Bayesian viewpoint is adopted; the observation density is 2-pi-periodic and accounts for the interferometric pair decorrelation and system noise; the a priori probability of the absolute phase is modeled by a compound Gauss-Markov random field (CGMRF) tailored to piecewise smooth absolute phase images. We propose an iterative scheme for the computation of the maximum a posteriori probability (MAP) absolute phase estimate. Each iteration embodies a discrete optimization step (Z-step), implemented by network programming techniques and an iterative conditional modes (ICM) step (pi-step). Accordingly, the algorithm is termed ZpiM, where the letter M stands for maximization. An important contribution of the paper is the simultaneous implementation of phase unwrapping (inference of the 2pi-multiples) and smoothing (denoising of the observations). This improves considerably the accuracy of the absolute phase estimates compared to methods in which the data is low-pass filtered prior to unwrapping. A set of experimental results, comparing the proposed algorithm with alternative methods, illustrates the effectiveness of our approach.

  3. Non-interferometric quantitative phase imaging of yeast cells

    NASA Astrophysics Data System (ADS)

    Poola, Praveen K.; Pandiyan, Vimal Prabhu; John, Renu

    2015-12-01

    Real-time imaging of live cells is quite difficult without the addition of external contrast agents. Various methods for quantitative phase imaging of living cells have been proposed like digital holographic microscopy and diffraction phase microscopy. In this paper, we report theoretical and experimental results of quantitative phase imaging of live yeast cells with nanometric precision using transport of intensity equations (TIE). We demonstrate nanometric depth sensitivity in imaging live yeast cells using this technique. This technique being noninterferometric, does not need any coherent light sources and images can be captured through a regular bright-field microscope. This real-time imaging technique would deliver the depth or 3-D volume information of cells and is highly promising in real-time digital pathology applications, screening of pathogens and staging of diseases like malaria as it does not need any preprocessing of samples.

  4. Interferometric Reflectance Imaging Sensor (IRIS)—A Platform Technology for Multiplexed Diagnostics and Digital Detection

    PubMed Central

    Avci, Oguzhan; Lortlar Ünlü, Nese; Yalçın Özkumur, Ayça; Ünlü, M. Selim

    2015-01-01

    Over the last decade, the growing need in disease diagnostics has stimulated rapid development of new technologies with unprecedented capabilities. Recent emerging infectious diseases and epidemics have revealed the shortcomings of existing diagnostics tools, and the necessity for further improvements. Optical biosensors can lay the foundations for future generation diagnostics by providing means to detect biomarkers in a highly sensitive, specific, quantitative and multiplexed fashion. Here, we review an optical sensing technology, Interferometric Reflectance Imaging Sensor (IRIS), and the relevant features of this multifunctional platform for quantitative, label-free and dynamic detection. We discuss two distinct modalities for IRIS: (i) low-magnification (ensemble biomolecular mass measurements) and (ii) high-magnification (digital detection of individual nanoparticles) along with their applications, including label-free detection of multiplexed protein chips, measurement of single nucleotide polymorphism, quantification of transcription factor DNA binding, and high sensitivity digital sensing and characterization of nanoparticles and viruses. PMID:26205273

  5. Optimization of grating duty cycle in non-interferometric grating-based X-ray phase contrast imaging

    NASA Astrophysics Data System (ADS)

    Luo, Ronghui; Wu, Zhao; Xiong, Ying; Wei, Chenxi; Zhang, Xiaobo; Hu, Renfang; Wang, Lei; Guo, Liang; Liu, Gang; Tian, Yangchao

    2017-08-01

    Grating-based X-ray phase contrast imaging technology is one of the most potential imaging methods in real applications. It can be classified into two categories: interferometry and non-interferometric imaging. The non-interferometric grating-based X-ray phase contrast imaging (NIGPCI) instrument has a great advantage in the forthcoming commercial applications for the flexible system design and the use of large periodic gratings. The performance of the NIGPCI instrument depends on its angular sensitivity to a great extent. Therefore, good angular sensitivity is mandatory in order to obtain high quality phase-contrast images. Several parameters, such as the X-ray spectrum, the inter-grating distances, and the parameters of the three gratings, influence the angular sensitivity of the imaging system. However, the quantitative relationship between the angular sensitivity and grating duty cycle is unclear. Therefore, this paper is devoted to revealing their internal relation by theoretical deduction and emulation of the imaging process with the theories of linear system and Fourier optics. Furthermore, a quantitative analysis method to optimize the duty cycles of gratings is proposed and its applicability to a general NIGPCI system is verified.

  6. Using dynamic interferometric synthetic aperature radar (InSAR) to image fast-moving surface waves

    DOEpatents

    Vincent, Paul

    2005-06-28

    A new differential technique and system for imaging dynamic (fast moving) surface waves using Dynamic Interferometric Synthetic Aperture Radar (InSAR) is introduced. This differential technique and system can sample the fast-moving surface displacement waves from a plurality of moving platform positions in either a repeat-pass single-antenna or a single-pass mode having a single-antenna dual-phase receiver or having dual physically separate antennas, and reconstruct a plurality of phase differentials from a plurality of platform positions to produce a series of desired interferometric images of the fast moving waves.

  7. Design and calibration of a piezoelectric actuator for interferometric applications

    NASA Astrophysics Data System (ADS)

    Bruno, Luigi; Poggialini, Andrea; Felice, Giuseppina

    2007-12-01

    The present work reports a possible solution for a low-cost piezoelectric actuator available for interferometric applications. In the paper the design, the assembly and the calibration of the actuator are described in detail. The solution adopted consists of a machined stainless steel case deformed by three low-voltage multilayer plumbum zirconate titanate (PZT) ceramic blocks. In the proposed arrangement a three degree of freedom device is obtained, by which a translation and two rotations can be performed. The PZTs are driven by a supply voltage provided by a 16 bit D/A converter directly connected to the parallel port of a personal computer which guarantees a very accurate output. This voltage is applied on each ceramic by means of a variable resistor, by which it is possible to adjust the maximum driving voltage for the single block. This electrical solution allows to match up the strokes of the ceramics in order to obtain a straight expansion of the whole actuator. After the mechanical and electrical set-up of the actuator, a static calibration was carried out by inserting it along one arm of a Michelson speckle interferometer. The calibration procedure had emphasized the hysteresis loop and the non-linearity of the electromechanical behaviour of the actuator.

  8. High-speed quantitative interferometric microscopy based phase imaging cytometer

    NASA Astrophysics Data System (ADS)

    Xue, Liang; Sun, Nan; Yan, Keding; Liu, Fei; Wang, Shouyu

    2014-11-01

    The paper proposed a simple large scale bio-sample phase detecting equipment called gravity driven phase detecting cytometer, which is based on quantitative interferometric microscopy to realize flowing red blood cells phase distribution detection. The method has advantages on high throughput phase detecting and statistical analysis with high detecting speed and in real-time. The statistical characteristics of red blood cells are useful for biological analysis and disease detection. We believe this method is shedding more light on quantitatively measurement of the phase distribution of bio-samples.

  9. MORESANE: MOdel REconstruction by Synthesis-ANalysis Estimators. A sparse deconvolution algorithm for radio interferometric imaging

    NASA Astrophysics Data System (ADS)

    Dabbech, A.; Ferrari, C.; Mary, D.; Slezak, E.; Smirnov, O.; Kenyon, J. S.

    2015-04-01

    Context. Recent years have been seeing huge developments of radio telescopes and a tremendous increase in their capabilities (sensitivity, angular and spectral resolution, field of view, etc.). Such systems make designing more sophisticated techniques mandatory not only for transporting, storing, and processing this new generation of radio interferometric data, but also for restoring the astrophysical information contained in such data. Aims.In this paper we present a new radio deconvolution algorithm named MORESANEand its application to fully realistic simulated data of MeerKAT, one of the SKA precursors. This method has been designed for the difficult case of restoring diffuse astronomical sources that are faint in brightness, complex in morphology, and possibly buried in the dirty beam's side lobes of bright radio sources in the field. Methods.MORESANE is a greedy algorithm that combines complementary types of sparse recovery methods in order to reconstruct the most appropriate sky model from observed radio visibilities. A synthesis approach is used for reconstructing images, in which the synthesis atoms representing the unknown sources are learned using analysis priors. We applied this new deconvolution method to fully realistic simulations of the radio observations of a galaxy cluster and of an HII region in M 31. Results.We show that MORESANE is able to efficiently reconstruct images composed of a wide variety of sources (compact point-like objects, extended tailed radio galaxies, low-surface brightness emission) from radio interferometric data. Comparisons with the state of the art algorithms indicate that MORESANE provides competitive results in terms of both the total flux/surface brightness conservation and fidelity of the reconstructed model. MORESANE seems particularly well suited to recovering diffuse and extended sources, as well as bright and compact radio sources known to be hosted in galaxy clusters.

  10. Rapid interferometric imaging of printed drug laden multilayer structures

    NASA Astrophysics Data System (ADS)

    Sandler, Niklas; Kassamakov, Ivan; Ehlers, Henrik; Genina, Natalja; Ylitalo, Tuomo; Haeggstrom, Edward

    2014-02-01

    The developments in printing technologies allow fabrication of micron-size nano-layered delivery systems to personal specifications. In this study we fabricated layered polymer structures for drug-delivery into a microfluidic channel and aimed to interferometrically assure their topography and adherence to each other. We present a scanning white light interferometer (SWLI) method for quantitative assurance of the topography of the embedded structure. We determined rapidly in non-destructive manner the thickness and roughness of the structures and whether the printed layers containing polymers or/and active pharmaceutical ingredients (API) adhere to each other. This is crucial in order to have predetermined drug release profiles. We also demonstrate non-invasive measurement of a polymer structure in a microfluidic channel. It shown that traceable interferometric 3D microscopy is a viable technique for detailed structural quality assurance of layered drug-delivery systems. The approach can have impact and find use in a much broader setting within and outside life sciences.

  11. Rapid interferometric imaging of printed drug laden multilayer structures

    PubMed Central

    Sandler, Niklas; Kassamakov, Ivan; Ehlers, Henrik; Genina, Natalja; Ylitalo, Tuomo; Haeggstrom, Edward

    2014-01-01

    The developments in printing technologies allow fabrication of micron-size nano-layered delivery systems to personal specifications. In this study we fabricated layered polymer structures for drug-delivery into a microfluidic channel and aimed to interferometrically assure their topography and adherence to each other. We present a scanning white light interferometer (SWLI) method for quantitative assurance of the topography of the embedded structure. We determined rapidly in non-destructive manner the thickness and roughness of the structures and whether the printed layers containing polymers or/and active pharmaceutical ingredients (API) adhere to each other. This is crucial in order to have predetermined drug release profiles. We also demonstrate non-invasive measurement of a polymer structure in a microfluidic channel. It shown that traceable interferometric 3D microscopy is a viable technique for detailed structural quality assurance of layered drug-delivery systems. The approach can have impact and find use in a much broader setting within and outside life sciences. PMID:24503863

  12. Interferometric imaging of the underside of a subducting crust

    NASA Astrophysics Data System (ADS)

    Poliannikov, O. V.; Rondenay, S.; Chen, L.

    2011-12-01

    Seismic interferometry provides tools for redatuming physical data to a source location. Placing a virtual receiver close to a structure of interest has the potential benefit of improving the quality of imaging by increasing the effective aperture and mitigating the effect of velocity uncertainty in the overburden. We consider the problem of estimating the Green's function between two earthquakes located inside a subducting slab using earthquake data recorded at the surface. Our primary focus is to obtain an accurate time-image of the subducting interface. Known techniques, such as classical or source-receiver interferometry, are not directly applicable due to inadequate acquisition geometry. We propose a two-step kinematically correct redatuming procedure that first redatums the data from earthquakes below the subducting interface to the surface via classical interferometry, and then utilizes source-receiver wavefield interferometry to redatum virtual surface seismic data to the location of a particular earthquake event.

  13. Interferometric and optical tests of water window imaging x ray microscopes

    NASA Technical Reports Server (NTRS)

    Johnson, R. Barry

    1993-01-01

    Interferometric tests of Schwarzchild X-ray Microscope are performed to evaluate the optical properties and alignment of the components. Photographic measurements of the spatial resolution, focal properties, and vignetting characteristics of the prototype Water Window Imaging X-ray Microscope are made and analyzed.

  14. Interferometric imaging of crustal structure from wide-angle multicomponent OBS-airgun data

    NASA Astrophysics Data System (ADS)

    Shiraishi, K.; Fujie, G.; Sato, T.; Abe, S.; Asakawa, E.; Kodaira, S.

    2015-12-01

    In wide-angle seismic surveys with ocean bottom seismograph (OBS) and airgun, surface-related multiple reflections and upgoing P-to-S conversions are frequently observed. We applied two interferometric imaging methods to the multicomponent OBS data in order to highly utilize seismic signals for subsurface imaging.First, seismic interferometry (SI) is applied to vertical component in order to obtain reflection profile with multiple reflections. By correlating seismic traces on common receiver records, pseudo seismic data are generated with virtual sources and receivers located on all original shot positions. We adopt the deconvolution SI because source and receiver spectra can be canceled by spectral division. Consequently, gapless reflection images from just below the seafloor to the deeper are obtained.Second, receiver function (RF) imaging is applied to multicomponent OBS data in order to image P-to-S conversion boundary. Though RF is commonly applied to teleseismic data, our purpose is to extract upgoing PS converted waves from wide-angle OBS data. The RF traces are synthesized by deconvolution of radial and vertical components at same OBS location for each shot. Final section obtained by stacking RF traces shows the PS conversion boundaries beneath OBSs. Then, Vp/Vs ratio can be estimated by comparing one-way traveltime delay with two-way traveltime of P wave reflections.We applied these methods to field data sets; (a) 175 km survey in Nankai trough subduction zone using 71 OBSs with from 1 km to 10 km intervals and 878 shots with 200 m interval, and (b) 237 km survey in northwest pacific ocean with almost flat layers before subduction using 25 OBSs with 6km interval and 1188 shots with 200 m interval. In our study, SI imaging with multiple reflections is highly applicable to OBS data even in a complex geological setting, and PS conversion boundary is well imaged by RF imaging and Vp/Vs ratio distribution in sediment is estimated in case of simple structure.

  15. The LINC-NIRVANA Fizeau interferometric imager: final lab integration, first light experiments and challenges

    NASA Astrophysics Data System (ADS)

    Herbst, T. M.; Ragazzoni, R.; Eckart, A.; Weigelt, G.

    2014-07-01

    LINC-NIRVANA (LN) is an innovative Fizeau interferometric imager for the Large Binocular Telescope (LBT). LN uses Multi-Conjugate Adaptive Optics (MCAO) for high-sky-coverage single-eye imagery and interferometric beam combination. The last two years have seen both successes and challenges. On the one hand, final integration is proceeding well in the lab. We also achieved First Light at the LBT with the Pathfinder experiment. On the other hand, funding constraints have forced a significant re-planning of the overall instrument implementation. These laboratory, observatory, and financial "events" provide lessons for builders of complex interferometric instruments on large telescopes. This paper presents our progress and plans for bringing the instrument online at the telescope.

  16. Fiber-optic interferometric acoustic sensors for wind tunnel applications

    NASA Technical Reports Server (NTRS)

    Cho, Y. C.

    1993-01-01

    Progress in developing fiber-optic interferometric sensors for aeroacoustic measurements in wind tunnels, performed under the NASA program, is reported. Preliminary results show that the fiber-optic interferometer sensor array is a powerful instrument for solving complex acoustic measurement problems in wind tunnels, which cannot be resolved with the conventional transducer technique.

  17. Fiber-optic interferometric acoustic sensors for wind tunnel applications

    NASA Technical Reports Server (NTRS)

    Cho, Y. C.

    1993-01-01

    Progress in developing fiber-optic interferometric sensors for aeroacoustic measurements in wind tunnels, performed under the NASA program, is reported. Preliminary results show that the fiber-optic interferometer sensor array is a powerful instrument for solving complex acoustic measurement problems in wind tunnels, which cannot be resolved with the conventional transducer technique.

  18. Noise Removal in Interferometric Fringe Patterns: Application to Quantitative Stress Determination Using Speckle Interferometry

    NASA Astrophysics Data System (ADS)

    Diallo, M.; Rumzan, I.; Schmitt, D. R.

    2001-12-01

    Dual beam " Electronic speckle Interferometry" (EPSI) is used to record stress-relief displacements induced by the drilling of blind holes into prestressed materials. Interpretation of the resulting interferograms in term of stress magnitude can be achieved by iterative least squares minimization approach that uses the positions of fringes minima and maxima. An automated picking of these extrema can often be difficult because of superimposed noise that degrade the data quality. To improve the accuracy subsequent fringe positions picking, we apply a nonlinear image filtering technique based on inhomogeneous diffusion to remove the noise and smooth the extrema. In this technique, the image is represented as a surface in three-space and the inhomogeneous diffusion is based on analogy to the heat diffusion with the particularity that the conduction coefficient, taken as the inverse of the surface gradient is spatially variant. The rate of the surface diffusion is only dependent on the average value of the normal curvature in any two orthogonal directions and not on its magnitude thus allowing preservation of image structure. The noise removal process is achieved through averaging of its divergent direction. This averaging preserves "clean" image structures as their direction is nondivergent. Application of this technique on both synthetic and experimental data provided satisfactory results. Although our application focuses on the determination of mechanical parameters, the method could be directly applied to assist the interpretation of SAR interferometric fringe patterns or in reducing the noise in otherwise coherent seismic images. >http://www-geo.phys.ualberta.ca/ ~irumzan

  19. Simultaneous interferometric in-focus and out-of-focus imaging of ice crystals

    NASA Astrophysics Data System (ADS)

    Kielar, Justin Jacquot; Lemaitre, Pascal; Gobin, Carole; Yingchun, Wu; Porcheron, Emmanuel; Coetmellec, Sébastien; Grehan, Gérard; Brunel, Marc

    2016-08-01

    Using a freezing column, dendrite-like ice crystals are generated and characterized simultaneously using in-focus imaging and interferometric out-of-focus imaging. This simultaneous analysis allows a validation of size measurements made from the analysis of the 2D-autocorrelation of speckle-like interferometric out-of-focus patterns of ice crystals. Measurements of the same particles by in-focus and out-of-focus techniques are in good agreement for 75% of the particles tested. Simulations of out-of-focus patterns are in very good agreement with experimental images. The analysis of the 2D-Fourier transform of the speckle-like patterns confirms that it is possible to evaluate the 2D-autocorrelation of the global shape of the particle (i.e. its 2D-projection on the plane of the CCD sensor).

  20. Pulse shaping strategies for nonlinear interferometric vibrational imaging optimized for biomolecular imaging.

    PubMed

    Marks, Daniel L; Vinegoni, Claudio; Bredfeldt, Jeremy S; Boppart, Stephen A

    2004-01-01

    Nonlinear interferometric vibrational imaging (NIVI) measures the temporal cross-correlation of anti-Stokes radiation from coherent anti-Stokes Raman scattering (CARS) processes to achieve increased sensitivity, stray light rejection, and nonresonant background rejection. Because the intensity of CARS radiation is proportional to the square of the molecular density of a target resonance, it is critical to maximize the recoverable signal for a given illumination level. Especially if one desires to measure several resonances, there can be a sensitivity as well as a speed advantage to measuring them simultaneously rather than serially. We discuss the methods of sample excitation that NIVI allows and their potential sensitivity advantages, as well as present experimental results demonstrating Raman signal recovery using these pulse sequences.

  1. High-Speed Nonlinear Interferometric Vibrational Imaging of Biological Tissue With Comparison to Raman Microscopy

    PubMed Central

    Benalcazar, Wladimir A.; Chowdary, Praveen D.; Jiang, Zhi; Marks, Daniel L.; Chaney, Eric J.; Gruebele, Martin; Boppart, Stephen A.

    2011-01-01

    Vibrational contrast imaging of the distribution of complex biological molecules requires the use of techniques that provide broadband spectra with sufficient resolution. Coherent anti-Stokes Raman scattering (CARS) microscopy is currently limited in meeting these requirements due to the presence of a nonresonant background and its inability to target multiple resonances simultaneously. We present nonlinear interferometric vibrational imaging (NIVI), a technique based on CARS that uses femtosecond pump and Stokes pulses to retrieve broadband vibrational spectra over 200 cm–1 (full-width at half maximum). By chirping the pump and performing spectral interferometric detection, the anti-Stokes pulses are resolved in time. This phase-sensitive detection allows suppression of not only the nonresonant background, but also of the real part of the nonlinear susceptibility χ(3), improving the spectral resolution and features to make them comparable to those acquired with spontaneous Raman microscopy, as shown for a material sample and mammary tissue. PMID:22058432

  2. High-Speed Nonlinear Interferometric Vibrational Imaging of Biological Tissue With Comparison to Raman Microscopy.

    PubMed

    Benalcazar, Wladimir A; Chowdary, Praveen D; Jiang, Zhi; Marks, Daniel L; Chaney, Eric J; Gruebele, Martin; Boppart, Stephen A

    2009-12-04

    Vibrational contrast imaging of the distribution of complex biological molecules requires the use of techniques that provide broadband spectra with sufficient resolution. Coherent anti-Stokes Raman scattering (CARS) microscopy is currently limited in meeting these requirements due to the presence of a nonresonant background and its inability to target multiple resonances simultaneously. We present nonlinear interferometric vibrational imaging (NIVI), a technique based on CARS that uses femtosecond pump and Stokes pulses to retrieve broadband vibrational spectra over 200 cm(-1) (full-width at half maximum). By chirping the pump and performing spectral interferometric detection, the anti-Stokes pulses are resolved in time. This phase-sensitive detection allows suppression of not only the nonresonant background, but also of the real part of the nonlinear susceptibility χ((3)), improving the spectral resolution and features to make them comparable to those acquired with spontaneous Raman microscopy, as shown for a material sample and mammary tissue.

  3. Interferometric aperture synthesis for next generation passive millimetre wave imagers

    NASA Astrophysics Data System (ADS)

    Salmon, Neil A.; Wilkinson, Peter; Taylor, Chris

    2012-10-01

    This paper discusses the phase effects in the near-field associated with aperture synthesis imaging. The results explain why in some regions of the near-field it is possible to use Fourier transform techniques on a visibility function to create images. However, to generate images deep inside the near-field alternative processing techniques such as the G-matrix method are required. Algorithms based on this technique are used to process imagery from a proof of concept 22 GHz aperture synthesis imager [1]. Techniques for generating synthetic cross-correlations for the aperture synthesis technique are introduced and these are then validated using the image creation algorithms and real data from the proof of concept imager. Using these data the phenomenon of aliasing is explored. The simulation code is then used to illustrate how the effects of aliasing may be minimised by randomising the locations of the antennas over the aperture. The simulation tool is used to show how in the near field the technique can provide a range resolution in 3D imaging of a couple of millimetres when operating with a wavelength of 13 mm. Moving to illustrate the quality of images generated by a next generation aperture synthesis imagers, the software is extended to systems with hundreds of receiver channels.

  4. Stochastic Optics: A Scattering Mitigation Framework for Radio Interferometric Imaging

    NASA Astrophysics Data System (ADS)

    Johnson, Michael D.

    2016-12-01

    Just as turbulence in the Earth’s atmosphere can severely limit the angular resolution of optical telescopes, turbulence in the ionized interstellar medium fundamentally limits the resolution of radio telescopes. We present a scattering mitigation framework for radio imaging with very long baseline interferometry (VLBI) that partially overcomes this limitation. Our framework, “stochastic optics,” derives from a simplification of strong interstellar scattering to separate small-scale (“diffractive”) effects from large-scale (“refractive”) effects, thereby separating deterministic and random contributions to the scattering. Stochastic optics extends traditional synthesis imaging by simultaneously reconstructing an unscattered image and its refractive perturbations. Its advantages over direct imaging come from utilizing the many deterministic properties of the scattering—such as the time-averaged “blurring,” polarization independence, and the deterministic evolution in frequency and time—while still accounting for the stochastic image distortions on large scales. These distortions are identified in the image reconstructions through regularization by their time-averaged power spectrum. Using synthetic data, we show that this framework effectively removes the blurring from diffractive scattering while reducing the spurious image features from refractive scattering. Stochastic optics can provide significant improvements over existing scattering mitigation strategies and is especially promising for imaging the Galactic Center supermassive black hole, Sagittarius A*, with the Global mm-VLBI Array and with the Event Horizon Telescope.

  5. Interferometric imaging of geostationary satellites: signal-to-noise considerations

    NASA Astrophysics Data System (ADS)

    Jorgensen, A. M.; Schmitt, H.; Mozurkewich, D.; Armstrong, J. T.; Restaino, S.; Hindsley, R.

    2012-07-01

    Geostationary satellites are generally too small to image at high resolution with conventional single-dish tele- scopes. An alternative to a 100+ m diameter telescope is to use an optical/infrared interferometer consisting of multiple smaller telescopes in an array configuration. In this paper we focus on what is required to achieve the required signal-to-noise ratio to image. We will look at the signal-to-noise ratio required to track fringes on satellites on multiple baselines, a pre-requisite to imaging.We will also look at how to achieve the required signal- to-noise required for image reconstruction. We compare these performance specifications to the performance of existing interferometers as well as that of a new interferometer concept optimized for satellite imaging.

  6. A Fourier dimensionality reduction model for big data interferometric imaging

    NASA Astrophysics Data System (ADS)

    Vijay Kartik, S.; Carrillo, Rafael E.; Thiran, Jean-Philippe; Wiaux, Yves

    2017-06-01

    Data dimensionality reduction in radio interferometry can provide savings of computational resources for image reconstruction through reduced memory footprints and lighter computations per iteration, which is important for the scalability of imaging methods to the big data setting of the next-generation telescopes. This article sheds new light on dimensionality reduction from the perspective of the compressed sensing theory and studies its interplay with imaging algorithms designed in the context of convex optimization. We propose a post-gridding linear data embedding to the space spanned by the left singular vectors of the measurement operator, providing a dimensionality reduction below image size. This embedding preserves the null space of the measurement operator and hence its sampling properties are also preserved in light of the compressed sensing theory. We show that this can be approximated by first computing the dirty image and then applying a weighted subsampled discrete Fourier transform to obtain the final reduced data vector. This Fourier dimensionality reduction model ensures a fast implementation of the full measurement operator, essential for any iterative image reconstruction method. The proposed reduction also preserves the independent and identically distributed Gaussian properties of the original measurement noise. For convex optimization-based imaging algorithms, this is key to justify the use of the standard ℓ2-norm as the data fidelity term. Our simulations confirm that this dimensionality reduction approach can be leveraged by convex optimization algorithms with no loss in imaging quality relative to reconstructing the image from the complete visibility data set. Reconstruction results in simulation settings with no direction dependent effects or calibration errors show promising performance of the proposed dimensionality reduction. Further tests on real data are planned as an extension of the current work. matlab code implementing the

  7. An interferometric imaging test bench: The densified pupil concept applied to the VLTI.

    NASA Astrophysics Data System (ADS)

    Patru, Fabien; Mourard, Denis; Lardière, Olivier; Spang, Alain; Clausse, Jean-Michel; Bresson, Yves; Lagarde, Stéphane

    2004-12-01

    The purpose of this poster is to present a test bench that we are developing at Observatoire de la Cote d'Azut to study the performances of interferometric imaging systems. The goal is to study the densified pupil concept in different configurations of the VLTI. This work is linked to the next generation instrument VIDA (VLTI Imaging with a Densified Array). This bench is used to specify the technical requirements like tip-tilt correction and cophasing. We will compare the imaging performances of the aperture synthesis, Fizeau and densified pupils configuration.

  8. Interferometric Imaging of Geostationary Satellites: Signal-to-Noise Considerations

    DTIC Science & Technology

    2011-09-01

    and the extent to which they cover the necessary portions of the UV plane . Once the photon counting noise becomes smaller than the UV coverage noise, ad...satellites,” in Proc. SPIE 4091, Imaging Technology and Telescopes, J. W. Bilbro, J. B. Breckinridge, R. A. Carreras , S. R. Czyzak, M. J. Eckart, R. D...SPIE 4091, Imaging Technology and Telescopes, J. W. Bilbro, J. B. Breckinridge, R. A. Carreras , S. R. Czyzak, M. J. Eckart, R. D. Fiete, and P. S

  9. Optical buffer films for high-speed interferometric imaging

    NASA Astrophysics Data System (ADS)

    Lysogorski, Charles D.

    1995-02-01

    To understand wind tunnel flow-field turbulence, it is necessary to understand how high speed (kHz) transient events develop in time. The framing rates necessary to record such imagery are too high for conventional video camera systems to be used. While high-speed, film-based cameras (e.g. Cordin drum film recorders) have sufficient spatial resolution and framing rates, analyzing the data acquired with these cameras is time consuming, possibly taking days to process and digitize the film images. These limitations in existing digital imaging technologies, and pulsed flow-field illumination systems have prevented digital movies of phenomena in turbulent and unstable flow-field regions to be made with sufficient spatial and temporal resolution. To address this need, I am presenting two techniques which can record data onto an intermediate optical buffer with the desired temporal and spatial resolution. These optical buffers incorporate real-time erasable recording film which consist of a phosphor or bacteriorhodopsin (BR) that would be used to temporarily store the images which were recorded at kHz rates. These images are then reconstructed and digitized at standard video rates, and stored on an optical disk. The primary advantage of this technique is in the ability to record images at extremely fast rates (60 kHz or faster) and then digitize the images at standard video recording rates.

  10. Three-dimensional interferometric ISAR imaging for target scattering diagnosis and modeling.

    PubMed

    Xu, X; Narayanan, R M

    2001-01-01

    Two-dimensional (2-D) inverse synthetic aperture radar (ISAR) imaging has been widely used in target scattering diagnosis, modeling and target identification. A major shortcoming is that a 2-D ISAR image cannot provide information on the relative altitude of each scattering center on the target. In this paper, we present an interferometric inverse synthetic aperture radar (IF-ISAR) image processing technique for three-dimensional (3-D) target altitude image formation. The 2-D ISAR images are obtained from the signature data acquired as a function of frequency and azimuthal angle. A 3-D IF-ISAR altitude image can then be derived from two 2-D images reconstructed from the measurements by antennas at different altitudes. 3-D altitude image formation examples from both indoor and outdoor test range data are demonstrated on complex radar targets.

  11. Perturbation methods in optics: application to the interferometric measurement of surfaces.

    PubMed

    Garbusi, Eugenio; Osten, Wolfgang

    2009-12-01

    Manufacturing and misalignment errors are present in every optical system. Usually these errors lead to intolerable wavefront deviations and system inaccuracies if they are not characterized and taken into consideration. In the interferometric measurement of surfaces, the characterization of the interferometer aberrations plays a central role, since unknown phase contributions lead to an erroneous assessment of the test surface and therefore an incorrect estimation of the performance of an optical system. In this work, we present a method for the interferometric characterization of surfaces based on the principles of Hamilton's characteristic functions and perturbation theory. The application of the proposed method to an interferometer for the measurement of aspherical surfaces is shown.

  12. An overview of interferometric metrology and NDT techniques and applications for the aerospace industry

    NASA Astrophysics Data System (ADS)

    Georges, Marc P.; Thizy, Cédric; Languy, Fabian; Vandenrijt, Jean-François

    2016-08-01

    We review some full-field interferometric techniques which have been successfully applied in different applications related to the aerospace industry. The first part of the paper concerns the long-wave infrared (LWIR) digital holographic interferometry which allows the measurement large displacements that occur when space structures undergo large temperature excursions. A second part of the paper concerns different developments in interferometric nondestructive testing (NDT) techniques intended to improve their usability in aerospace industrial environments. Among others, we discuss LWIR speckle interferometry for simultaneous deformation and temperature variation measurements and new post-processing techniques applied to shearography for an easier detection of flaws in composite structures.

  13. Interferometric imaging of the underside of a subducting crust

    NASA Astrophysics Data System (ADS)

    Poliannikov, Oleg V.; Rondenay, Stéphane; Chen, Ling

    2012-04-01

    Seismic interferometry provides tools for redatuming physical data to a new source location. Turning a source, located close to a structure of interest, into a virtual receiver has the potential benefit of improving the quality of imaging by increasing the effective aperture and mitigating the effect of velocity uncertainty in the overburden. Here, we consider the problem of estimating the Green's function between two earthquakes located inside a subducting slab using earthquake data recorded at the surface. Our primary focus is to obtain an accurate time-image of the subducting interface. We propose a novel two-step kinematically correct redatuming procedure that first redatums the data from earthquakes below the subducting interface to the surface via classical interferometry, and then utilizes source-receiver wavefield interferometry to redatum virtual surface seismic data to the location of a particular earthquake event.

  14. A regularized tri-linear approach for optical interferometric imaging

    NASA Astrophysics Data System (ADS)

    Birdi, Jasleen; Repetti, Audrey; Wiaux, Yves

    2017-06-01

    In the context of optical interferometry, only undersampled power spectrum and bispectrum data are accessible. It poses an ill-posed inverse problem for image recovery. Recently, a tri-linear model was proposed for monochromatic imaging, leading to an alternated minimization problem. In that work, only a positivity constraint was considered, and the problem was solved by an approximated Gauss-Seidel method. In this paper, we propose to improve the approach on three fundamental aspects. First, we define the estimated image as a solution of a regularized minimization problem, promoting sparsity in a fixed dictionary using either an ℓ1 or a (re)weighted-ℓ1 regularization term. Secondly, we solve the resultant non-convex minimization problem using a block-coordinate forward-backward algorithm. This algorithm is able to deal both with smooth and non-smooth functions, and benefits from convergence guarantees even in a non-convex context. Finally, we generalize our model and algorithm to the hyperspectral case, promoting a joint sparsity prior through an ℓ2,1 regularization term. We present simulation results, both for monochromatic and hyperspectral cases, to validate the proposed approach.

  15. Optical probing of exploding wires using schlieren and interferometric imaging.

    NASA Astrophysics Data System (ADS)

    Romanova, V. M.; Pikuz, S. A.; Shelkovenko, T. A.; Hu, Min; Sinars, D. B.; Kusse, B. R.; Dimant, Ya. S.; Greenly, J. B.; Hummer, D. A.

    1999-11-01

    Optical diagnostics using an Nd:YAG laser (l=532 nm) were used to probe exploding fine wires (7.5-20 mm initial diameter) driven by a sinusoidal 4.5/,kA current pulse (350 ns risetime). Phase transitions from vapor to plasma have been directly observed during the explosion process of various wire materials (Al, Au, etc.). Three simultaneous schlieren channels and 1--3 interferometry channels were used. For some experiments, the schlieren channels were made up of a bright-field iris, a dark-field knife edge, and a dark-field strip block. For other experiments, three bright-field images were made at 10 ns intervals. Interferometry was performed using a new astigmatism-free shearing interferometer based on a double-prism air wedge. The images were made with a 4 ns exposure time at 50--2000 ns after the start of the wire current. Simultaneous X-ray backlighting [1] of the wires enabled reliable interpretation of the optical images, and with a step wedge [2] was used to measure the ion density. Combining the ion density and electron density measurements allowed us to estimate the ionization state of the exploded wire. 1. T.A.Shelkovenko, S.A.Pikuz, A.R.Mingaleev, D.A.Hammer, Rev. Sci. Instrum., 70, 667 (1999). 2. S.A.Pikuz, T.A.Shelkovenko, A.R.Mingaleev, H.Neves, D.A.Hammer, Phys. Plasmas (in press).

  16. Image processing automatic interferometric calibration system for line scales

    NASA Astrophysics Data System (ADS)

    Gonzalez, Hector; Galvan, Carlos; Muñoz, J. A.

    2003-11-01

    An automatic calibration bench to calibrate line scales up to three meters has been developed at the Centro Nacional de Metrologia. It incorporates an heterodyne laser interferometer to follow the position of a carriage that support a microscope with a CCD camera. The images are processed using a novel robust algorithm to determine the center of each line. The carriage travels along guide ways and is commanded by a computer that controls the servomotor that moves it, allowing to complete the calibration automatically. The measurement and control software developed uses an image processing algorithm based on Gabor filters and robust statistics to discriminate between lines and unwanted features that may exist such as stain, scratches, rust, etc. It then calculates the absolute position of each line by coupling the reading of the carriage position given by the interferometer and the centerline position of the line in the image. Additionally, the software corrects the laser readings for ambient condition variations and controls the progress of the carriage. The mechanical design consists of a stiff bench with guide ways on which the carriage travels. Although the carriage travels in non-kinematic guide ways, the microscope and CCD camera sit on a plate that is kinematically supported. The movement is provided by a servomotor and transmitted by means of a screw. Uncertainty is expected to be between 3 and 10 um which is common to other similar systems. The gross advantage is the ability to calibrate automatically and discriminate defects on the scale.

  17. Imaging and interferometric analysis of protein crystal growth

    NASA Astrophysics Data System (ADS)

    Raghunandan, Ranjini; Gupta, Anamika Sethia; Muralidhar, K.

    2008-04-01

    Protein crystals are grown under controlled temperature, concentration and vapor pressure conditions, usually by vapor diffusion, liquid-liquid diffusion and dialysis techniques. The present study examines the effects of protein concentration, drop size and reservoir height on the crystal growth of Hen Egg White Lysozyme (HEWL). Crystals are grown by the hanging drop vapor diffusion method using Modular VDX TM Plates. Due to the vapor pressure difference created between the protein drop and the reservoir, evaporation takes place till equilibrium is attained. Crystal formation takes place after a certain level of supersaturation is attained when the protein precipitates out in crystalline form. The observations revealed that the growth is faster for higher lysozyme concentration, smaller drop sizes and larger reservoir heights. The morphology of the crystals is viewed during the growth process using stereomicroscope. The number of crystals formed is the maximum for higher concentrations, drop sizes and reservoir heights. When the number of crystals formed is less, the size of the crystals is comparatively larger. The effect of evaporation of water vapor from the protein drop into the reservoir is studied using Mach-Zehnder interferometry. The recorded interferograms and shadowgraph images indicate the diffusion of condensed water into the reservoir. The radius of the drop is determined using the shadowgraph images of the growth process. The radius decreases with evaporation and the rate of decrease of radius is highest for higher protein concentrations, smaller drop sizes and larger reservoir heights.

  18. Interferometric time-stretch microscopy for ultrafast quantitative cellular and tissue imaging at 1 μm

    NASA Astrophysics Data System (ADS)

    Lau, Andy K. S.; Wong, Terence T. W.; Ho, Kenneth K. Y.; Tang, Matthew T. H.; Chan, Antony C. S.; Wei, Xiaoming; Lam, Edmund Y.; Shum, Ho Cheung; Wong, Kenneth K. Y.; Tsia, Kevin K.

    2014-07-01

    Quantitative phase imaging (QPI) has been proven to be a powerful tool for label-free characterization of biological specimens. However, the imaging speed, largely limited by the image sensor technology, impedes its utility in applications where high-throughput screening and efficient big-data analysis are mandated. We here demonstrate interferometric time-stretch (iTS) microscopy for delivering ultrafast quantitative phase cellular and tissue imaging at an imaging line-scan rate >20 MHz-orders-of-magnitude faster than conventional QPI. Enabling an efficient time-stretch operation in the 1-μm wavelength window, we present an iTS microscope system for practical ultrafast QPI of fixed cells and tissue sections, as well as ultrafast flowing cells (at a flow speed of up to 8 m/s). To the best of our knowledge, this is the first time that time-stretch imaging could reveal quantitative morphological information of cells and tissues with nanometer precision. As many parameters can be further extracted from the phase and can serve as the intrinsic biomarkers for disease diagnosis, iTS microscopy could find its niche in high-throughput and high-content cellular assays (e.g., imaging flow cytometry) as well as tissue refractometric imaging (e.g., whole-slide imaging for digital pathology).

  19. 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.

  20. An interferometric imaging test bench: the densified pupil concept applied to the VLTI

    NASA Astrophysics Data System (ADS)

    Patru, Fabien; Mourard, Denis; Lardiere, Olivier; Spang, Alain; Clausse, Jean-Michel; Antonelli, Pierre; Bresson, Yves; Lagarde, Stephane

    2004-10-01

    We describe a test bench designed to study the performances of interferometric imaging systems. The main goal is to study the densified pupil concept in the framework of the VLTI. This work is linked to the proposition of a second generation instrument called VIDA (VLTI Imaging with a Densified Array). This bench aims at comparing the imaging performances of the aperture synthesis, Fizeau and densified pupils beam combination schemes and at specifying the technical requirements like cophasing and tip-tilt correction. A Fizeau assembly, using a multi-apertures mask and associated with a wavefront sensor, has been designed. It allows to measure the differential piston between sub-apertures and to link them to the characteristics of the image recovered. A densified assembly is under study by using reflective surfaces or optical fibers to carry the beams and to densify the pupils before the combination.

  1. Impact of focusing of Ground Based SAR data on the quality of interferometric SAR applications

    NASA Astrophysics Data System (ADS)

    Zonno, Mariantonietta; Mascolo, Luigi; Guccione, Pietro; Nico, Giovanni; Di Pasquale, Andrea

    2014-10-01

    A Ground-Based Synthetic Aperture Radar (GB-SAR) is nowadays employed in several applications. The processing of ground-based, space and airborne SAR data relies on the same physical principles. Nevertheless specific algorithms for the focusing of data acquired by GB-SAR system have been proposed in literature. In this work the impact of the main focusing methods on the interferometric phase dispersion and on the coherence has been studied by employing a real dataset obtained by carrying out an experiment. Several acquisitions of a scene with a corner reflector mounted on a micrometric screw have been made; before some acquisitions the micrometric screw has been displaced of few millimetres in the Line-of-Sight direction. The images have been first focused by using two different algorithms and correspondently, two different sets of interferograms have been generated. The mean and standard deviation of the phase values in correspondence of the corner reflector have been compared to those obtained by knowing the real displacement of the micrometric screw. The mean phase and its dispersion and the coherence values for each focusing algorithm have been quantified and both the precision and the accuracy of the interferometic phase measurements obtained by using the two different focusing methods have been assessed.

  2. Improving image quality in intensity-interferometric spectral-domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Shirai, Tomohiro

    2016-07-01

    Intensity-interferometric spectral-domain optical coherence tomography (I-SD-OCT), devised recently as a classical analog of quantum OCT, enables axially scanless cross-sectional imaging with an immunity to group-velocity dispersion and a factor-of-\\sqrt{2} resolution improvement. However, unwanted artifacts inevitably emerge in the resultant image. In this paper, it is demonstrated theoretically and experimentally that such artifacts can be reduced without any difficulty by means of either a mechanical displacement of the detector for capturing spectral intensity patterns or a numerical displacement of the spectral intensity patterns stored in a computer. Furthermore, it is proved that the I-SD-OCT signal can be extracted from the conventional SD-OCT setup under a certain condition. These two features serve to improve the image quality in I-SD-OCT.

  3. Interferometric Remapped Array Nulling

    NASA Astrophysics Data System (ADS)

    Vakili, F.; Aristidi, E.; Abe, L.; Lopez, B.

    2004-07-01

    This paper describes a method of beam-combination in the so-called hypertelescope imaging technique recently introduced by Labeyrie in optical interferometry. The method we propose is an alternative to the Michelson pupil reconfiguration that suffers from the loss of the classical object-image convolution relation. From elementary theory of Fourier optics we demonstrate that this problem can be solved by reconfiguring images instead of pupils. Imaging is performed in a combined pupil-plane where the point-source intensity distribution (PSID by comparison to the more commonly quoted point-spread function, PSF) tends towards a pseudo Airy disc for a sufficiently large number of telescopes. Our method is applicable to snap-shot imaging of extended sources with a field limited to the Airy pattern of single telescopes operated in a co-phased multi-aperture interferometric array. It thus allows to apply conveniently pupil plane coronagraphy. Our technique called Interferometric Remapped Array Nulling (IRAN) is particularly suitable for high dynamic imaging of extra-solar planetary companions or extra-galactic objects where long baseline interferometry would closely probe the central regions of AGNs for instance. We also discuss the application of IRAN to improve the performances of imaging and/or nulling interferometers like the full-fledged VLTI array or the DARWIN space-borne mission.

  4. Very Long Baseline Interferometry (VLBI) earth physics. [application to radio astronomy and interferometric earth surveys

    NASA Technical Reports Server (NTRS)

    Macdoran, P. F.

    1972-01-01

    The characteristics of the Michelson/Pease stellar interferometer are discussed. An analog of the interferometer using radio waves is described. The use of a conventional hard-wired interferometer with very long base line interferometry (VLBI) is analyzed. Mathematical models are developed to analyze the VLBI techniques. A summary of VLBI geodetic experiments is tabulated. The concept and application of the astronomical radio interferometric earth surveys (ARIES) are reported. A schematic diagram of ARIES implementation is provided.

  5. Very Long Baseline Interferometry (VLBI) earth physics. [application to radio astronomy and interferometric earth surveys

    NASA Technical Reports Server (NTRS)

    Macdoran, P. F.

    1972-01-01

    The characteristics of the Michelson/Pease stellar interferometer are discussed. An analog of the interferometer using radio waves is described. The use of a conventional hard-wired interferometer with very long base line interferometry (VLBI) is analyzed. Mathematical models are developed to analyze the VLBI techniques. A summary of VLBI geodetic experiments is tabulated. The concept and application of the astronomical radio interferometric earth surveys (ARIES) are reported. A schematic diagram of ARIES implementation is provided.

  6. Interferometric direct imaging properties of a BIGRE-DAM device in laboratory

    NASA Astrophysics Data System (ADS)

    Patru, Fabien; Antichi, Jacopo; Rabou, Patrick; Giro, Enrico; Farinato, Jacopo; Gratton, Raffaele; Vassallo, Daniele; Verinaud, Christophe; Mourard, Denis; Girard, Julien

    2016-08-01

    DAM (Discretized Aperture Mapping) is an original optical concept able to improve the performance in high angular resolution and high contrast imaging by the present class of large telescopes equipped with adaptive optics. By discretizing the entrance pupil of a large telescope into an array of many coherent sub-apertures, DAM provides unique imaging and filtering properties by means of spatial filtering and interferometric techniques. DAM can be achieved by means of single-mode fibers, integrated optic waveguides, pinholes, or simply with an innovative BIGRE optical device. BIGRE is formed of an afocal double micro-lenses array. In addition to the pupil discretization process by spatial filtering, BIGRE can also provide two other optical processes: the pupil densification or the pupil dilution. DAD (Discretized Aperture Densification) increase the sub-aperture sizes and is suitable to a hypertelescope, whereas DADI (Discretized Aperture Dilution Interferometry) reduces the sub-aperture sizes and turns a large telescope into a Fizeau interferometer. This paper deals with the first in-lab experiment at visible wavelength of BIGRE devices for the three configurations above. We study the point spread function (PSF) when observing a point-like object located either on-axis or at various off-axis positions across the field of view. Both interferometric and diffractive effects are described. The experimental measurements are in good agreement with the BIGRE theory. It results that BIGRE fulfils the requirements to carry out spatially filtered pupil discretization (DAM), with possible densification (DAD) or dilution (DADI).

  7. Monitoring water level using Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) images

    NASA Astrophysics Data System (ADS)

    Stavroulaki, Eleni; Alexakis, Dimitrios D.; Tsanis, Ioannis K.

    2017-04-01

    Interferometric Synthetic Aperture Radar (SAR) methodology can successfully detect phase variations related to water level changes and produce corresponding water level maps. Two lakes located in Western Crete, Greece, namely Lake Kournas and Lake Agia were used as case studies to study water level change with means of SAR interferometry. The change of the water surface in the lake is examined over a period of two years, 2015-2016 using Sentinel 1 IW mode images and in situ water level data. Initially, all the SAR images were preprocessed in terms of atmospheric and radiometric corrections. Various interferograms were developed to study the multi-temporal regime of water level in both lakes. Optical satellite sensor data (Landsat 8) were used to study the vegetation regime and how this affect the interferogram processing. The results denoted the fact that the combination of SAR backscattering intensity and unwrapped phase water level data can provide additional insight into hydrological state. It is also shown that integrated analysis of the backscattering mechanism and interferometric characteristics can considerably enhance the reliability of the water-level retrieval scheme and optimize the capture of hydrological patterns spatial distribution. Keywords: Sentinel-1, interferogram, water level, Backscattering

  8. Nonlinear interferometric vibrational imaging for fast label-free visualization of molecular domains in skin

    PubMed Central

    Benalcazar, Wladimir A.

    2011-01-01

    The most prevalent molecular constituents of skin are spatially mapped by the use of nonlinear interferometric vibrational imaging, a coherent anti-Stokes Raman scattering (CARS)-based technique. Raman-like profiles over the range from 2,800 to 3,000 cm−1 are acquired by means of completely suppressing the non-resonant background, allowing the generation of images based on the molecule-specific spectral profiles over the probed region with high spatial resolution. A simple algorithm that maps spectral content to color allows the visualization of histology in a manner analogous to that obtained with more conventional staining procedures (e.g., hematoxylin-eosin), but faster and with the benefit of having access to localized spectra, which could further enhance the potential for diagnosis of diseases, especially during the early stages of development. PMID:21465094

  9. Nonlinear interferometric vibrational imaging for fast label-free visualization of molecular domains in skin.

    PubMed

    Benalcazar, Wladimir A; Boppart, Stephen A

    2011-07-01

    The most prevalent molecular constituents of skin are spatially mapped by the use of nonlinear interferometric vibrational imaging, a coherent anti-Stokes Raman scattering (CARS)-based technique. Raman-like profiles over the range from 2,800 to 3,000 cm(-1) are acquired by means of completely suppressing the non-resonant background, allowing the generation of images based on the molecule-specific spectral profiles over the probed region with high spatial resolution. A simple algorithm that maps spectral content to color allows the visualization of histology in a manner analogous to that obtained with more conventional staining procedures (e.g., hematoxylin-eosin), but faster and with the benefit of having access to localized spectra, which could further enhance the potential for diagnosis of diseases, especially during the early stages of development.

  10. THE AzTEC/SMA INTERFEROMETRIC IMAGING SURVEY OF SUBMILLIMETER-SELECTED HIGH-REDSHIFT GALAXIES

    SciTech Connect

    Younger, Joshua D.; Fazio, Giovanni G.; Huang Jiasheng; Ashby, Matthew L. N.; Gurwell, Mark A.; Petitpas, Glen R.; Wilner, David J.; Yun, Min S.; Wilson, Grant W.; Scott, Kimberly S.; Austermann, Jason; Perera, Thushara; Peck, Alison B.; Hughes, David H.; Aretxaga, Itziar; Kim, Sungeun; Lowenthal, James D.

    2009-10-10

    We present results from a continuing interferometric survey of high-redshift submillimeter galaxies (SMGs) with the Submillimeter Array, including high-resolution (beam size approx2 arcsec) imaging of eight additional AzTEC 1.1 mm selected sources in the COSMOS field, for which we obtain six reliable (peak signal-to-noise ratio (S/N) >5 or peak S/N >4 with multiwavelength counterparts within the beam) and two moderate significance (peak S/N >4) detections. When combined with previous detections, this yields an unbiased sample of millimeter-selected SMGs with complete interferometric follow up. With this sample in hand, we (1) empirically confirm the radio-submillimeter association, (2) examine the submillimeter morphology-including the nature of SMGs with multiple radio counterparts and constraints on the physical scale of the far infrared-of the sample, and (3) find additional evidence for a population of extremely luminous, radio-dim SMGs that peaks at higher redshift than previous, radio-selected samples. In particular, the presence of such a population of high-redshift sources has important consequences for models of galaxy formation-which struggle to account for such objects even under liberal assumptions-and dust production models given the limited time since the big bang.

  11. Image registration of interferometric inverse synthetic aperture radar imaging system based on joint respective window sampling and modified motion compensation

    NASA Astrophysics Data System (ADS)

    Tian, Biao; Shi, Si; Liu, Yang; Xu, Shiyou; Chen, Zengping

    2015-01-01

    We propose a new image registration method based on joint respective window sampling (RWS) and modified motion compensation (MMC) in an interferometric inverse synthetic aperture radar (InISAR) imaging system using two antennas. The causation and quantitative analysis of the offset between two ISAR images of different antennas along the baseline are analyzed. In the proposed method, the RWS method, according to the measured distance between the target and different antennas, compensates the offset in the range direction. The MMC method is adopted to eliminate the offset in the Doppler direction. Simulation results demonstrate that the offset between the two ISAR images can be compensated effectively, consequently achieving a high-quality three-dimensional InISAR image.

  12. Smear Fitting: A New Method of Obtaining Images From Interferometric Data

    NASA Astrophysics Data System (ADS)

    Reid, Robert

    A new method is presented for producing images from incompletely sampled interferometric data. The method, "smear fitting", models the source with a set of basis functions and then convolves each component with an elliptical Gaussian to account for the uncertainty in its shape and location. This produces much sharper resolution for high signal to noise components than CLEAN without harm to low signal to noise features. It also lends itself to using data from multiple polarizations and/or frequencies to obtain an optimum set of images. Physical insight can also be incorporated by changing the choice of basis function(s). Smear fitting does not require reweighting or even gridding of the data in the production and display of the model, preserving all of the information in the data both in terms of sensitivity and resolution. It is compared to other methods of producing images in radio interferometry. The comparisons are amply illustrated with both real and simulated data. Smear fitting is found to have sharper resolution than CLEAN, without striping or gridding errors. Although it is similar in principle to maximum entropy deconvolution, by using fewer degrees of freedom it avoids "ringing" artefacts around sharp features embedded in smooth emission. Its processing time is competitive with the other methods and best for objects that require many pixels but can be modeled with relatively few components, such as a set of sharp features superimposed on a smoothly varying background. Two problems of fitting Gaussians to interferometric data are discussed and solved. These improvements in model fitting made it possible to automate smear fitting, and the details of the process are explained. Smear fitting is applied to study the precession of extragalactic radio jets and measure the thickness of the planetary nebula Vy 2-2, and results from those studies are given.

  13. Imaging the noncentrosymmetric structural organization of tendon with Interferometric Second Harmonic Generation microscopy.

    PubMed

    Rivard, Maxime; Popov, Konstantin; Couture, Charles-André; Laliberté, Mathieu; Bertrand-Grenier, Antony; Martin, François; Pépin, Henri; Pfeffer, Christian P; Brown, Cameron; Ramunno, Lora; Légaré, François

    2014-08-01

    We report the imaging of tendon with Interferometric Second Harmonic Generation microscopy. We observe that the noncentrosymmetric structural organization can be maintained along the fibrillar axis over more than 150 μm, while in the transverse direction it is ∼1-15 μm. Those results are explained by modeling tendon as a heterogeneous distribution of noncentrosymmetric nano-cylinders (collagen fibrils) oriented along the fibrillar axis. The preservation of the noncentrosymmetric structural organization over multiple tens of microns reveals that tendon is made of domains in which the ratio between fibrils with positive and negative polarity is unbalanced. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Contextual filtering method applied to sub-bands of interferometric image decomposition

    NASA Astrophysics Data System (ADS)

    Belhadj-Aissa, S.; Hocine, F.; Boughacha, M. S.; Belhadj-Aissa, M.

    2016-10-01

    The precision and accuracy of Digital elevation model and deformation measurement, from SAR interferometry (InSAR/DInSAR) depend mainly on the quality of the interferogram. However, the phase noise, which is mainly due to decorrelation between the images and the speckle, makes the step of phase unwrapping most delicate. In this paper, we propose a filtering method that combines the techniques of decomposition into sub-bands and nonlinear local weights. The Spectral / Contextual filter that we propose, inspired from to Goldstein filter is applied to the sub-bands from the wavelet decomposition. To validate the results, we applied to interferometric products tandem pair ERS1/ERS2 taken in the region of Algiers Algeria.

  15. Robust interferometric imaging via prior-less phase recovery: redundant spacing calibration with generalized-closure phases

    NASA Astrophysics Data System (ADS)

    Kurien, Binoy G.; Ashcom, Jonathan B.; Shah, Vinay N.; Rachlin, Yaron; Tarokh, Vahid

    2017-01-01

    Atmospheric turbulence presents a fundamental challenge to Fourier phase recovery in optical interferometry. Typical reconstruction algorithms employ Bayesian inference techniques which rely on prior knowledge of the scene under observation. In contrast, redundant spacing calibration (RSC) algorithms employ redundancy in the baselines of the interferometric array to directly expose the contribution of turbulence, thereby enabling phase recovery for targets of arbitrary and unknown complexity. Traditionally RSC algorithms have been applied directly to single-exposure measurements, which are reliable only at high photon flux in general. In scenarios of low photon flux, such as those arising in the observation of dim objects in space, one must instead rely on time-averaged, atmosphere-invariant quantities such as the bispectrum. In this paper, we develop a novel RSC-based algorithm for prior-less phase recovery in which we generalize the bispectrum to higher order atmosphere-invariants (n-spectra) for improved sensitivity. We provide a strategy for selection of a high-signal-to-noise ratio set of n-spectra using the graph-theoretic notion of the minimum cycle basis. We also discuss a key property of this set (wrap-invariance), which then enables reliable application of standard linear estimation techniques to recover the Fourier phases from the 2π-wrapped n-spectra phases. For validation, we analyse the expected shot-noise-limited performance of our algorithm for both pairwise and Fizeau interferometric architectures, and corroborate this analysis with simulation results showing performance near an atmosphere-oracle Cramer-Rao bound. Lastly, we apply techniques from the field of compressed sensing to perform image reconstruction from the estimated complex visibilities.

  16. Scalable splitting algorithms for big-data interferometric imaging in the SKA era

    NASA Astrophysics Data System (ADS)

    Onose, Alexandru; Carrillo, Rafael E.; Repetti, Audrey; McEwen, Jason D.; Thiran, Jean-Philippe; Pesquet, Jean-Christophe; Wiaux, Yves

    2016-11-01

    In the context of next-generation radio telescopes, like the Square Kilometre Array (SKA), the efficient processing of large-scale data sets is extremely important. Convex optimization tasks under the compressive sensing framework have recently emerged and provide both enhanced image reconstruction quality and scalability to increasingly larger data sets. We focus herein mainly on scalability and propose two new convex optimization algorithmic structures able to solve the convex optimization tasks arising in radio-interferometric imaging. They rely on proximal splitting and forward-backward iterations and can be seen, by analogy, with the CLEAN major-minor cycle, as running sophisticated CLEAN-like iterations in parallel in multiple data, prior, and image spaces. Both methods support any convex regularization function, in particular, the well-studied ℓ1 priors promoting image sparsity in an adequate domain. Tailored for big-data, they employ parallel and distributed computations to achieve scalability, in terms of memory and computational requirements. One of them also exploits randomization, over data blocks at each iteration, offering further flexibility. We present simulation results showing the feasibility of the proposed methods as well as their advantages compared to state-of-the-art algorithmic solvers. Our MATLAB code is available online on GitHub.

  17. Chemical imaging by single pulse interferometric coherent anti-stokes Raman scattering microscopy.

    PubMed

    Lim, Sang-Hyun; Caster, Allison G; Nicolet, Olivier; Leone, Stephen R

    2006-03-23

    A single pulse interferometric coherent anti-Stokes Raman (CARS) spectroscopy method is used to obtain broadband CARS spectra and microscopy images of liquid and polymer samples. The pump, Stokes, and probe pulses are all selected inside a single broadband ultrafast pulse by a phase- and polarization-controlled pulse shaping technique and used to generate two spectral interference CARS signals simultaneously. The normalized difference of these two signals provides an amplified background-free broadband resonant CARS spectrum over the 400-1500 cm(-1) range with 35 cm(-1) spectral resolution. Chemically selective microscopy images of multicomponent polymer and liquid samples are investigated with this new CARS method. Multiplex CARS spectra at 10,000 spatial points are measured within a few minutes, and used to construct chemically selective microscopy images with a spatial resolution of 400 nm. The spectral bandwidth limits, sensitivity, homodyne amplification advantages, spatial resolution, depolarization, chromatic aberration, and chemical imaging aspects of this new technique are discussed in detail.

  18. Discretized aperture mapping with a micro-lenses array for interferometric direct imaging

    NASA Astrophysics Data System (ADS)

    Patru, Fabien; Antichi, Jacopo; Mawet, Dimitri; Jolissaint, Laurent; Carbillet, Marcel; Milli, Julien; Girard, Julien; Rabou, Patrick; Giro, Enrico; Mourard, Denis

    2014-08-01

    Discretized Aperture Mapping (DAM) appears as an original filtering technique easy to play with existing adaptive optics (AO) systems. In its essential DAM operates as an optical passive filter removing part of the phase residuals in the wavefront without introducing any difficult-to-align component in the Fourier conjugate of the entrance pupil plane. DAM reveals as a new interferometric technique combined with spatial filtering allowing direct imaging over a narrow field of view (FOV). In fact, the entrance pupil of a single telescope is divided into many sub-pupils so that the residual phase in each sub-pupil is filtered up to the DAM cut-off frequency. DAM enables to smooth the small scale wavefront defects which correspond to high spatial frequencies in the pupil plane and to low angular frequencies in the image plane. Close to the AO Nyquist frequency, such pupil plane spatial frequencies are not well measured by the wavefront sensor (WFS) due to aliasing. Once bigger than the AO Nyquist frequency, they are no more measured by the WFS due to the fitting limit responsible for the narrow AO FOV. The corresponding image plane angular frequencies are not transmitted by DAM and are useless to image small FOVs, as stated by interferometry. That is why AO and DAM are complementary assuming that the DAM cut-off frequency is equal to the AO Nyquist frequency. Here we describe the imaging capabilities when DAM is placed downstream an AO system, over a convenient pupil which precedes the scientific detector. We show firstly that the imaging properties are preserved on a narrow FOV allowing direct imaging throughout interferometry. Then we show how the residual pupil plane spatial frequencies bigger than the AO Nyquist one are filtered out, as well as the residual halo in the image is dimmed.

  19. Seeing Stars Like Never Before: A Multi-Year Interferometric Imaging Study of Red Supergiants in the H-Band.

    NASA Astrophysics Data System (ADS)

    Norris, Ryan P.; Baron, Fabien

    2017-01-01

    As some of the largest stars, red supergiants (RSG) are ideal candidates for interferometric imaging. 3D radiative hydrodynamic (RHD) models suggest that RSG have large convection cells with lifetimes on the order of 1000s of days. Many imaging projects have hinted at the existence of these features but, until recently, we have lacked the angular resolution to directly compare models to observations. In this presentation, we discuss early results from a multi-year survey of red supergiants using the Michigan InfraRed Combinber (MIRC) on the Center for High Angular Resolution Astronomy (CHARA Array), which has a maximum baseline of 330 m. We will present H-band images of RSG spanning several years developed using a new machine learning based image reconstruction tool for interferometric data. We will also present fundamental parameters for the targets, and discuss the implications of these results on 1D model atmospheres and 3D RHD models of RSG.

  20. Discret aperture mapping with a micro-lenses array for interferometric direct imaging

    NASA Astrophysics Data System (ADS)

    Patru, Fabien; Antichi, Jacopo; Rabou, Patrick; Giro, Enrico; Mawet, Dimitri; Milli, Julien; Girard, Julien; Carbillet, Marcel; Mourard, Denis

    2013-12-01

    A challenging study for high resolution and high-contrast imaging is the detection and the characterization of planets in the habitable zone. The problem of detection in imaging is due to both the contrast ratio and the tiny separation between the hosting star and the exoplanet. Certainly, many techniques in high-contrast imaging will have to be optimized simultaneously to enhance the detection treshold and to probe the candidates for life. In this context, the objective is to demonstrate the technical faisability and to get scientific returns with a new concept called Discret Aperture Mapping or DAM (Patru et al. 2011). DAM is a new interferometric technique allowing high contrast imaging over a narrow field of view imaged by the present class of mono-pupil telescopes equipped with adaptive optics (AO). DAM consists in mapping the telescope pupil to provide a correct sampling of the spatial frequency content of the telescope. DAM can be realized by an afocal double lenslet array array (BIGRE-DAM, Antichi et al. 2011), or by a single-mode fiber combiner (Fibered-DAM, Patru et al. 2008). The spatial filtering used in interferometry allows to subdivide the entrance pupil of a large telescope into many coherent sub-pupils, so that the intra-sub-pupil residual phase is averaged out. On the other side, frequencies higher than the deformable mirror sampling one are not corected by AO impling aliasing effect and a strong impact of Fresnel propagation on the compensated wavefront up to the final focus (Antichi et al. 2010). DAM is then a high frequency optical filter able to remove part of the AO residuals and to remove most of the halo in the image. It may improve the contrast limit to explore the inner region of new stellar systems (disk, exoplanet). We show here first simulation results on the DAM concept.

  1. Plastic mine detecting radar system using complex-valued self-organizing map that deals with multiple-frequency interferometric images.

    PubMed

    Hara, Takahiro; Hirose, Akira

    2004-01-01

    Ground penetrating radars (GPR's) have been often applied to underground object imaging. However, conventional radar systems do not work sufficiently to detect anti-personnel plastic landmines. We propose a novel radar imaging system, which processes adaptively interferometric front-end data obtained at multiple-frequency points. The system deals with interferometric images using complex-valued self-organizing map (C-SOM). We demonstrate a successful visualization of a plastic mine buried near the ground surface.

  2. Forest height estimation from mountain forest areas using general model-based decomposition for polarimetric interferometric synthetic aperture radar images

    NASA Astrophysics Data System (ADS)

    Minh, Nghia Pham; Zou, Bin; Cai, Hongjun; Wang, Chengyi

    2014-01-01

    The estimation of forest parameters over mountain forest areas using polarimetric interferometric synthetic aperture radar (PolInSAR) images is one of the greatest interests in remote sensing applications. For mountain forest areas, scattering mechanisms are strongly affected by the ground topography variations. Most of the previous studies in modeling microwave backscattering signatures of forest area have been carried out over relatively flat areas. Therefore, a new algorithm for the forest height estimation from mountain forest areas using the general model-based decomposition (GMBD) for PolInSAR image is proposed. This algorithm enables the retrieval of not only the forest parameters, but also the magnitude associated with each mechanism. In addition, general double- and single-bounce scattering models are proposed to fit for the cross-polarization and off-diagonal term by separating their independent orientation angle, which remains unachieved in the previous model-based decompositions. The efficiency of the proposed approach is demonstrated with simulated data from PolSARProSim software and ALOS-PALSAR spaceborne PolInSAR datasets over the Kalimantan areas, Indonesia. Experimental results indicate that forest height could be effectively estimated by GMBD.

  3. VLTI/AMBER spectro-interferometric imaging of VX Sagittarii's inhomogenous outer atmosphere

    NASA Astrophysics Data System (ADS)

    Chiavassa, A.; Lacour, S.; Millour, F.; Driebe, T.; Wittkowski, M.; Plez, B.; Thiébaut, E.; Josselin, E.; Freytag, B.; Scholz, M.; Haubois, X.

    2010-02-01

    Aims: We aim to explore the photosphere of the very cool late-type star VX Sgr and in particular the characterization of molecular layers above the continuum forming photosphere. Methods: We obtained interferometric observations with the VLTI/AMBER interferometer using the fringe tracker FINITO in the spectral domain 1.45-2.50 μm with a spectral resolution of ≈35 and baselines ranging from 15 to 88 m. We performed independent image reconstruction for different wavelength bins and fit the interferometric data with a geometrical toy model. We also compared the data to 1D dynamical models of Miras atmosphere and to 3D hydrodynamical simulations of red supergiant (RSG) and asymptotic giant branch (AGB) stars. Results: Reconstructed images and visibilities show a strong wavelength dependence. The H-band images display two bright spots whose positions are confirmed by the geometrical toy model. The inhomogeneities are qualitatively predicted by 3D simulations. At ≈2.00 μm and in the region 2.35-2.50 μm, the photosphere appears extended and the radius is larger than in the H band. In this spectral region, the geometrical toy model locates a third bright spot outside the photosphere that can be a feature of the molecular layers. The wavelength dependence of the visibility can be qualitatively explained by 1D dynamical models of Mira atmospheres. The best-fitting photospheric models show a good match with the observed visibilities and give a photospheric diameter of Theta=8.82 ± 0.50 mas. The H2O molecule seems to be the dominant absorber in the molecular layers. Conclusions: We show that the atmosphere of VX Sgr seems to resemble Mira/AGB star model atmospheres more closely than do RSG model atmospheres. In particular, we see molecular (water) layers that are typical of Mira stars. Based on the observations made with VLTI-ESO Paranal, Chile under the programs IDs 081.D-0005(A, B, C, D, E, F, G, H).

  4. IRAN: interferometric remapped array nulling

    NASA Astrophysics Data System (ADS)

    Aristidi, Eric; Vakili, Farrokh; Abe, Lyu; Belu, Adrian; Lopez, Bruno; Lanteri, Henri; Schutz, A.; Menut, Jean-Luc

    2004-10-01

    This paper describes a method of beam-combination in the so-called hypertelescope imaging technique recently introduced by Labeyrie in optical interferometry. The method we propose is an alternative to the Michelson pupil reconfiguration that suffers from the loss of the classical object-image convolution relation. From elementary theory of Fourier optics we demonstrate that this problem can be solved by observing in a combined pupil plane instead of an image plane. The point-source intensity distribution (PSID) of this interferometric "image" tends towards a psuedo Airy disc (similar to that of a giant monolithic telescope) for a sufficiently large number of telescopes. Our method is applicable to snap-shot imaging of extended sources with a field comparable to the Airy pattern of single telescopes operated in a co-phased multi-aperture interferometric array. It thus allows to apply conveniently pupil plane coronagraphy. Our technique called Interferometric Remapped Array Nulling (IRAN) is particularly suitable for high dynamic imaging of extra-solar planetary companions, circumstellar nebulosities or extra-galactic objects where long baseline interferometry would closely probe the central regions of AGNs for instance.

  5. Direct Imaging and Interferometric Followup of Our Closest Low-Mass Stellar Neighbors

    NASA Astrophysics Data System (ADS)

    Girard, J.

    2014-04-01

    Luhman 16 AB is a L/T brown dwarf binary system at only 2 pc from us. Discovered a year ago thanks to WISE (Luhman 2013), it has already been extensively studied (spectral types, variability, cloud map, etc. a total of 8 refereed publications). In this contribution I tackle the possibility of following up such target with the state of the art high contrast imaging and interferometric techniques. Though the system isn't young, it is so close and its components have mild effective temperature that we can probe for planetary-mass companions down to solar system scales. I will present results from our deep NACO L'-band search and expose our strategy and attempt with VLTI/PIONIER H-band (four 8m telescopes) to reach the habitable zone (~0.005 AU) and provide direct upper limits on the diameter of both Luhman A and B. Finally I will discuss the possibility of tackling such objects with the coming generation of high contrast imagers.

  6. Influence of sample pool on interference pattern in defocused interferometric particle imaging

    NASA Astrophysics Data System (ADS)

    Zhang, Hongxia; Zhou, Ye; Liu, Jing; Jia, Dagong; Liu, Tiegen

    2017-04-01

    Particles widely exist in various fields. In practical experiments, sometimes it is necessary to dissolve particles in water in a sample pool. This article proposes two typical layouts of the sample pool in defocused interferometric particle imaging (IPI). Layout I is the sample pool surface perpendicular to the incident light and layout II is the sample pool surface perpendicular to the scattered light. For layout I, the scattered light of the particles does not keep symmetric at the meridional and sagittal planes after being refracted by the sample pool surface, and elliptical interference patterns are formed at the defocused IPI image plane. But for layout II, the scattered light keeps symmetric after being refracted, and circular interference patterns are formed. Aimed at the two sample pool layouts, the ray-tracing software ZEMAX was used to simulate the spot shape of particles at different defocus distances. Furthermore, its effect on the ellipticity of the interference pattern with the tilt angle of the sample pool is analyzed. The relative error of the axis ratio for layout I does not exceed 9.2% at different defocus distances. The experimental results have good agreement with the theoretical analyses, and it indicates that layout II is more reasonable for the IPI system.

  7. Advanced Interferometric Synthetic Aperture Imaging Radar (InSAR) for Dune Mapping

    NASA Astrophysics Data System (ADS)

    Havivi, Shiran; Amir, Doron; Schvartzman, Ilan; August, Yitzhak; Mamman, Shimrit; Rotman, Stanely R.; Blumberg, Dan G.

    2016-04-01

    Aeolian morphologies are formed in the presence of sufficient wind energy and available lose particles. These processes occur naturally or are further enhanced or reduced by human intervention. The dimensions of change are dependent primarily on the wind energy and surface properties. Since the 1970s, remote sensing imagery, both optical and radar, have been used for documentation and interpretation of the geomorphologic changes of sand dunes. Remote sensing studies of aeolian morphologies is mostly useful to document major changes, yet, subtle changes, occurring in a period of days or months in scales of centimeters, are very difficult to detect in imagery. Interferometric Synthetic Aperture Radar (InSAR) is an imaging technique for measuring Earth's surface topography and deformation. InSAR images are produced by measuring the radar phase difference between two separated antennas that view the same surface area. Classical InSAR is based on high coherence between two or more images. The output (interferogram) can show subtle changes with an accuracy of several millimeters to centimeters. Very little work has been done on measuring or identifying the changes in dunes using InSAR methods. The reason is that dunes tend to be less coherent than firm, stable, surfaces. This work aims to demonstrate how interferometric decorrelation can be used for identifying dune instability. We hypothesize and demonstrate that the loss of radar coherence over time on dunes can be used as an indication of the dune's instability. When SAR images are acquired at sufficiently close intervals one can measure the time it takes to lose coherence and associate this time with geomorphic stability. To achieve our goals, the coherence change detection method was used, in order to identify dune stability or instability and the dune activity level. The Nitzanim-Ashdod coastal dunes along the Mediterranean, 40 km south of Tel-Aviv, Israel, were chosen as a case study. The dunes in this area are of

  8. Diffractive optical variable image devices generated by maskless interferometric lithography for optical security

    NASA Astrophysics Data System (ADS)

    Cabral, Alexandre; Rebordão, José M.

    2011-05-01

    In optical security (protection against forgery and counterfeit of products and documents) the problem is not exact reproduction but the production of something sufficiently similar to the original. Currently, Diffractive Optically Variable Image Devices (DOVID), that create dynamic chromatic effects which may be easily recognized but are difficult to reproduce, are often used to protect important products and documents. Well known examples of DOVID for security are 3D or 2D/3D holograms in identity documents and credit cards. Others are composed of shapes with different types of microstructures yielding by diffraction to chromatic dynamic effects. A maskless interferometric lithography technique to generate DOVIDs for optical security is presented and compared to traditional techniques. The approach can be considered as a self-masking focused holography on planes tilted with respect to the reference optical axes of the system, and is based on the Scheimpflug and Hinge rules. No physical masks are needed to ensure optimum exposure of the photosensitive film. The system built to demonstrate the technique relies on the digital mirrors device MOEMS technology from Texas Instruments' Digital Light Processing. The technique is linear on the number of specified colors and does not depend either on the area of the device or the number of pixels, factors that drive the complexity of dot-matrix based systems. The results confirmed the technique innovation and capabilities in the creation of diffractive optical elements for security against counterfeiting and forgery.

  9. Computer simulations of interferometric imaging with the VLT Interferometer and the AMBER instrument

    NASA Astrophysics Data System (ADS)

    Bloecker, Thomas; Hofmann, Karl-Heinz; Przygodda, Frank; Weigelt, Gerd

    2000-07-01

    We present computer simulations of interferometric imaging with the VLT interferometer and the AMBER instrument. These simulations include both the astrophysical modeling of a stellar object by radiative transfer calculations and the simulation of light propagation from the object to the detector (through atmosphere, telescopes, and the AMBER instrument), simulation of photon noise and detector read- out noise, and finally data processing of the interferograms. The results show the dependence of the visibility error bars on the following observational parameters: different seeing during the observation of object and reference star (Fried parameters r0,object equals 2.4 m, r0,ref. equals 2.5 m), different residual tip- tilt error ((delta) tt,object equals 2% of the Airy disk diameter, (delta) tt,ref. equals 0.1%), and object brightness (Kobject equals 3.5 mag and 11 mag, Kref. equals 3.5 mag). Exemplarily, we focus on stars in late stages of stellar evolution and study one of its key objects, the dusty supergiant IRC + 10420 that is rapidly evolving on human timescales. We show computer simulations of VLTI interferometry of IRC + 10420 with two ATs (wide-field mode, i.e. without fiber optics spatial filters) and discuss whether the visibility accuracy is sufficient to distinguish between different theoretical model predictions.

  10. Non-convex optimization for self-calibration of direction-dependent effects in radio interferometric imaging

    NASA Astrophysics Data System (ADS)

    Repetti, Audrey; Birdi, Jasleen; Dabbech, Arwa; Wiaux, Yves

    2017-10-01

    Radio interferometric imaging aims to estimate an unknown sky intensity image from degraded observations, acquired through an antenna array. In the theoretical case of a perfectly calibrated array, it has been shown that solving the corresponding imaging problem by iterative algorithms based on convex optimization and compressive sensing theory can be competitive with classical algorithms such as clean. However, in practice, antenna-based gains are unknown and have to be calibrated. Future radio telescopes, such as the Square Kilometre Array, aim at improving imaging resolution and sensitivity by orders of magnitude. At this precision level, the direction-dependency of the gains must be accounted for, and radio interferometric imaging can be understood as a blind deconvolution problem. In this context, the underlying minimization problem is non-convex, and adapted techniques have to be designed. In this work, leveraging recent developments in non-convex optimization, we propose the first joint calibration and imaging method in radio interferometry, with proven convergence guarantees. Our approach, based on a block-coordinate forward-backward algorithm, jointly accounts for visibilities and suitable priors on both the image and the direction-dependent effects (DDEs). As demonstrated in recent works, sparsity remains the prior of choice for the image, while DDEs are modelled as smooth functions of the sky, i.e. spatially band-limited. Finally, we show through simulations the efficiency of our method, for the reconstruction of both images of point sources and complex extended sources. matlab code is available on GitHub.

  11. High-sensitivity ultrasound interferometric single-mode polymer optical fiber sensors for biomedical applications.

    PubMed

    Gallego, Daniel; Lamela, Horacio

    2009-06-15

    This work describes the results of ultrasonic wideband sensors based on single-mode polymer optical fibers that may be used for biomedical applications. We have compared the ultrasonic sensitivities of two Mach-Zehnder interferometric intrinsic optical fiber sensors. One is based on a single-mode polymethylmethacrylate optical fiber and the second on single-mode silica optical fiber, both operating at 632.8 nm. At a frequency of 1 MHz these sensitivities are 13.1 and 0.85 mrad/kPa, respectively. The ultrasonic phase sensitivity of the polymer optical fiber is more than 12 times larger than that from the fused silica fiber in the 1-5 MHz range.

  12. Multi-Frequency Synthesis - a New Technique in Radio Interferometric Imaging

    NASA Astrophysics Data System (ADS)

    Conway, J. E.; Cornwell, T. J.; Wilkinson, P. N.

    1990-10-01

    We describe an extension to aperture synthesis, multi-frequency synthesis or MFS, whose principal goal is to allow high-quality radio images to be obtained from spars interferometric arrays. The idea is to use data from a relatively narrow range of frequencies (typically +/- 10 per cent) to produce a major improvement in the aperture-plane coverage of an array. From these data one can reconstruct an image at a single reference frequency in which the 'reconstruction errors', which normally occur as a result of large 'holes' in the aperture plane, are much reduced. The obvious problem to -be overcome is that the source brightness distribution is slightly different at each frequency. We analyse the 'spectral errors' introduced into the reconstructed image by this frequency-dependent structure. For a +/- 1 2.5 per cent range of frequencies we show that typically, spectral errors will be below the thermal noise level provided that the ratio of the peak brightness (excluding any compact component such as a radio core) to rms noise is less than a thousand-to-one, Unresolved features can be identified easily and effectively removed from the data a each frequency and hence they need not be a source of spectral errors. When this spectral errors are above the noise they can be recognized and removed by an extension to the well-established CLEAN deconvolution methodi We call the new method 'double deconvolution', or DD, and demonstrate its effectiveness 0 simulated data. The primary motivation beyond narrow-band MFS observations is to produce improved intensity images, rather than to determine spectral index distributions. Although the DD algorithm effectively estimates the spectral index distribution in the course of removing spectral effects, these estimates will be crude and not generally of astrophysical use. We briefly consider the practical problems involved in making MFS observations and conclude that the major limiting factor is likely to be radio

  13. Simultaneous 3D location and size measurement of bubbles and sand particles in a flow using interferometric particle imaging.

    PubMed

    Ouldarbi, L; Pérret, G; Lemaitre, P; Porcheron, E; Coëtmellec, S; Gréhan, G; Lebrun, D; Brunel, M

    2015-09-01

    We present a system to characterize a triphasic flow in a 3D volume (air bubbles and solid irregular particles in water) using only one CCD sensor. A cylindrical interferometric out-of-focus imaging setup is used to determine simultaneously the 3D position and the size of bubbles and irregular sand particles in a flow. The 3D position of the particles is deduced from the ellipticity of their out-of-focus image. The size of bubbles is deduced from analysis of interference fringes. The characteristics of irregular sand particles are obtained from analysis of their speckle-like pattern. Experiments are confirmed by simulations.

  14. IRAN: Interferometric Remapped Array Nulling

    NASA Astrophysics Data System (ADS)

    Aristidi, E.; Vakili, F.; Schutz, A.; Lanteri, H.; Abe, L.; Belu, A.; Gori, P. M.; Lardière, O.; Lopez, B.; Menut, J. L.; Patru, F.

    IRAN is a method of beam-combination in the hypertelescope imaging technique recently introduced by Labeyrie in optical interferometry. We propose to observe the interferometric image in the pupil plane, performing multi-axial pupil plane interferometry. Imaging is performed in a combined pupil-plane where the point-source intensity distribution (PSID) tends towards a pseudo Airy disc for a sufficiently large number of telescopes. The image is concentrated into the limited support of the output pupil of the individual telescopes, in which the object-image convolution relation is conserved. Specific deconvolution algorithms have been developped for IRAN hypertelescope imagery, based upon Lucy-like iterative techniques. We show that the classical (image plane) and IRAN (pupil plane) hypertelescope imaging techniques are equivalent if one uses optical fibers for beam transportation. An application to the VLT/VIDA concept is presented.

  15. Applications of computer-generated holograms for interferometric measurement of large aspheric optics

    NASA Astrophysics Data System (ADS)

    Burge, James H.

    1995-08-01

    Interferometric optical testing using computer-generated holograms (CGH's) has proven to give highly accurate measurements of aspheric surfaces. New applications of CGH interferometry were developed to support the fabrication of the large, steep mirrors required by the next generation ground-based telescopes. A new test to certify null correctors was designed and implemented that uses small CGH's fabricated onto flat surfaces. This test solves the difficult problem of verifying the accuracy of the null correctors that are used for measuring primary mirrors. Several new techniques for hologram fabrication have been explored for this application. A second new use of CGH's was developed for measuring convex secondary mirrors using test plates with holograms fabricated onto concave spherical reference surfaces. This test provides efficient and accurate measurement of large aspheric convex mirrors. A polar coordinate laser writing machine was built for fabricating these patterns onto curved optical surfaces up to 1.8 meters in diameter and as fast as f/1. These powerful new techniques have been implemented and optimized at the Steward Observatory Mirror Laboratory to guide mirror polishing for large telescope projects. They can also be readily applied for measuring small aspheres to high accuracy.

  16. An interferometric radar for displacement measurement and its application in civil engineering structures

    NASA Astrophysics Data System (ADS)

    Su, D.; Nagayama, T.; Sun, Z.; Fujino, Y.

    2012-04-01

    Recent progress in radar techniques and systems has led to the development of a microwave interferometer, potentially suitable for non-contact displacement monitoring of civil engineering structures. This paper describes a new interferometric radar system, named IBIS-S, which is possible to measure the static or dynamic displacement at multiple points of structures simultaneously with high accuracy. In this paper, the technical characteristics and specification of the radar system is described. Subsequently, the actual displacement sensitivity of the equipment is illustrated using the laboratory tests with random motion upon a shake table. Finally the applications of the radar system to the measurement on a cable-stayed bridge and a prestressed concrete bridge are presented and discussed. Results show that the new system is an accurate and effective method to measure displacements of multiple targets of structures. It should be noted that the current system can only measure the vibration of the target position along the sensor's line of sight. Hence, proper caution should be taken when designing the sensor posture and prior knowledge of the direction of motion is necessary.

  17. Tunable coherent radiation at soft X-ray wavelengths: Generation and interferometric applications

    SciTech Connect

    Rosfjord, Kristine Marie

    2004-01-01

    The availability of high power, spectrally and spatially coherent soft x-rays (SXR) would facilitate a wide variety of experiments as this energy region covers the primary resonances of many magnetic and biological materials. Specifically, there are the carbon and oxygen K-edges that are critical for biological imaging in the water window and the L-edges of iron, nickel, and cobalt for which imaging and scattering studies can be performed. A new coherent soft X-ray branchline at the Advanced Light Source has begun operation (beamline 12.0.2). Using the third harmonic from an 8 cm period undulator, this branch delivers coherent soft x-rays with photon energies ranging from 200eV to 1keV. This branchline is composed of two sub-branches one at 14X demagnification and the other 8X demagnification. The former is optimized for use at 500eV and the latter at 800eV. Here the expected power from the third harmonic of this undulator and the beamline design and characterization is presented. The characterization includes measurements on available photon flux as well as a series of double pinhole experiments to determine the coherence factor with respect to transverse distance. The first high quality Airy patterns at SXR wavelengths are created with this new beamline. The operation of this new beamline allows for interferometry to be performed in the SXR region. Here an interferometric experiment designed to directly determine the index of refraction of a material under test is performed. Measurements are first made in the EUV region using an established beamline (beamline12.0.1) to measure silicon, ruthenium and tantalum silicon nitride. This work is then extended to the SXR region using beamline 12.0.2 to test chromium and vanadium.

  18. Development of a folded compact range and its application in performing coherent change detection and interferometric ISAR measurement

    SciTech Connect

    Sorensen, K.W.; Zittel, D.H.; Littlejohn, J.H.

    1996-09-01

    A folded compact range configuration has been developed at the Sandia National Laboratories` compact range antenna and radar cross section measurement facility as a means of performing indoor, environmentally controlled far-field simulations of synthetic aperture radar (SAR) measurements of distributed target samples (i.e. gravel, sand, etc.). In particular, the folded compact range configuration has been used to perform both highly sensitive coherent change detection (CCD) measurements and interferometric inverse synthetic aperture radar (IFSAR) measurements, which, in addition to the two-dimensional spatial resolution afforded by typical interferometric SAR (ISAR) processing, provides resolution of the relative height of targets with accuracies on the order of a wavelength. This paper describes the development of the folded compact range, as well as the coherent change detection and interferometric measurements that have been made with the system. The measurement have been very successful, and have demonstrated not only the viability of the folded compact range concept in simulating SAR CCD and IFSAR measurements, but also its usefulness as a tool in the research and development of SAR CCD and IFSAR image generation and measurement methodologies.

  19. High-resolution interferometric radar images of equatorial spread F scattering structures using Capon's method

    NASA Astrophysics Data System (ADS)

    Zewdie, G. K.; Rodrigues, F. S.; Paula, E. R.

    2015-12-01

    Coherent backscatter radar imaging techniques use measurements made by multiple antenna baselines (visibility estimates) to infer the spatial distribution of the scatterers (brightness function) responsible for the observed echoes. It has been proposed that the Capon method for spectral estimation can be used for high-resolution estimation of the brightness distribution. We investigate the application of the Capon method to measurements made by a small (7-baseline) 30 MHz ionospheric coherent backscatter radar interferometer in Sao Luis, Brazil. The longest baseline of the interferometer is only 15 times the wavelength of radar signal (10 m), and the ionospheric radar soundings have been made using only 4-8 kW transmitters. Nevertheless, we have been able to obtain high-resolution (kilometric scales in the zonal direction) images of scattering structures during equatorial spread F (ESF) events over a wide field of view (+/- 10 degrees off zenith). We will present numerical simulations demonstrating the performance of the technique for the Sao Luis radar setup as well as results of the Capon technique applied to actual measurements. We will discuss the behavior of the ESF scattering structures as seen in the Capon images. The high-resolution images can assist our interpretation of plasma instabilities in the equatorial ionosphere and serve to test our ability to model the behavior of ionospheric irregularities during space weather events such as those associated with ESF.

  20. Sparse interferometric millimeter-wave array for centimeter-level 100-m standoff imaging

    NASA Astrophysics Data System (ADS)

    Suen, Jonathan Y.; Lubin, Philip M.; Solomon, Steven L.; Ginn, Robert P.

    2013-05-01

    We present work on the development of a long range standoff concealed weapons detection system capable of imaging under very heavy clothing at distances exceeding 100 m with a cm resolution. The system is based off a combination of phased array technologies used in radio astronomy and SAR radar by using a coherent, multi-frequency reconstruction algorithm which can run at up to 1000 Hz frame rates and high SNR with a multi-tone transceiver. We show the flexible design space of our system as well as algorithm development, predicted system performance and impairments, and simulated reconstructed images. The system can be used for a variety of purposes including portal applications, crowd scanning and tactical situations. Additional uses include seeing through dust and fog.

  1. Detection and evaluation of droplet and bubble fringe patterns in images of planar interferometric measurement techniques using the wavelet transform

    NASA Astrophysics Data System (ADS)

    Hardalupas, Y.; Taylor, A. M. K. P.; Zarogoulidis, K.

    2014-08-01

    The acquired images of interferometric particle sizing techniques are characterized by intense fringe pattern overlapping in dense droplet and bubble areas, which hinders the image processing process and subsequent information extraction. Methods employed, such as thresholding and the Hough transform and template cross-correlation, exhibit weaknesses when processing such dense areas of interest. We investigate the viability of applying the wavelet transform (WT) for the detection of the fringe pattern centers and the evaluation of the particle size. We present the basics of the WT using the Mexican hat, which exhibits excellent localization properties and present two different alternatives routes in detecting the fringe patterns in the compressed and uncompressed fringe pattern cases. We found that in comparison to the most reported methods for image evaluation, such as intensity thresholding and plain cross-correlation, the WT is a very efficient tool for detecting the patterns, even in images with high-number fringe pattern areas. The usage of the WT for the sizing of the imaged droplets and bubbles is also examined, in comparison to the Fast Fourier Transform (FFT).

  2. Interferometric Remapped Array Nulling

    NASA Astrophysics Data System (ADS)

    Abe, L.; Aristidi, E.; Vakili, F.; Domiciano, A.

    We present an interferometric beam recombination technique which allows achromatic and direct true imaging of targets at very high angular resolution. This technique intrinsically overcomes the main problems of Labeyrie's hypertelescope design, and can be used in a nulling configuration. It is thus particularly well suited for high contrast imaging in the context of exo-planet search and characterization especially for future space-borne arrays. We present the concept on a formal basis, and discuss its instrumental implementation.

  3. Interferometric Dynamic Measurement: Techniques Based on High-Speed Imaging or a Single Photodetector

    PubMed Central

    Fu, Yu; Pedrini, Giancarlo

    2014-01-01

    In recent years, optical interferometry-based techniques have been widely used to perform noncontact measurement of dynamic deformation in different industrial areas. In these applications, various physical quantities need to be measured in any instant and the Nyquist sampling theorem has to be satisfied along the time axis on each measurement point. Two types of techniques were developed for such measurements: one is based on high-speed cameras and the other uses a single photodetector. The limitation of the measurement range along the time axis in camera-based technology is mainly due to the low capturing rate, while the photodetector-based technology can only do the measurement on a single point. In this paper, several aspects of these two technologies are discussed. For the camera-based interferometry, the discussion includes the introduction of the carrier, the processing of the recorded images, the phase extraction algorithms in various domains, and how to increase the temporal measurement range by using multiwavelength techniques. For the detector-based interferometry, the discussion mainly focuses on the single-point and multipoint laser Doppler vibrometers and their applications for measurement under extreme conditions. The results show the effort done by researchers for the improvement of the measurement capabilities using interferometry-based techniques to cover the requirements needed for the industrial applications. PMID:24963503

  4. Stellar Rotation and Proto-Planetary Disks: What Interferometric Imaging and High Cadence Photometry Can Tell Us

    NASA Astrophysics Data System (ADS)

    Parks, James; White, R. J.; Plavchan, P.; Monnier, J. D.; Baron, F.; Henry, G. W.; Kloppenborg, B. K.; Che, X.; Schaefer, G.; Zhao, M.; Jones, J.; Pedretti, E.; Thureau, N.; ten Brummelaar, T.; Farrington, C. D.; McAlister, H. A.; Sturmann, J.; Sturmann, L.; Turner, N. H.; Ridgway, S. T.

    2013-01-01

    Presented are the results of a dissertation project. We present the first interferometric images of cool starspots on the magnetically active giant lambda Andromeda (Lam And). The 12 images span various rotational phases in 2010 and 2011, which allow us to directly characterize the starspot's temperature, location and size. Stellar rotation can be identified in the 6 images from 2011 that comprise ~40% of one rotation of Lam And. In a complementary starspot study, we highlight results of a 3 year near-IR photometric monitoring of young stars in the rho Ophiuchus star-forming region based on 2MASS calibration field observations. Of 101 variable stars identified, 32 exhibit periodic variability. For 6 variable stars, two different physical mechanisms are believed to be operating concurrently. The variability of 3 of these stars is believed to be caused by periodic occulations of spotted star, potentially sustained or driven by a proto-planet or a warped disk, at or near the co-rotation radius.

  5. Observing the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA): High-Resolution Interferometric Imaging

    NASA Astrophysics Data System (ADS)

    Shimojo, M.; Bastian, T. S.; Hales, A. S.; White, S. M.; Iwai, K.; Hills, R. E.; Hirota, A.; Phillips, N. M.; Sawada, T.; Yagoubov, P.; Siringo, G.; Asayama, S.; Sugimoto, M.; Brajša, R.; Skokić, I.; Bárta, M.; Kim, S.; de Gregorio-Monsalvo, I.; Corder, S. A.; Hudson, H. S.; Wedemeyer, S.; Gary, D. E.; De Pontieu, B.; Loukitcheva, M.; Fleishman, G. D.; Chen, B.; Kobelski, A.; Yan, Y.

    2017-07-01

    Observations of the Sun at millimeter and submillimeter wavelengths offer a unique probe into the structure, dynamics, and heating of the chromosphere; the structure of sunspots; the formation and eruption of prominences and filaments; and energetic phenomena such as jets and flares. High-resolution observations of the Sun at millimeter and submillimeter wavelengths are challenging due to the intense, extended, low-contrast, and dynamic nature of emission from the quiet Sun, and the extremely intense and variable nature of emissions associated with energetic phenomena. The Atacama Large Millimeter/submillimeter Array (ALMA) was designed with solar observations in mind. The requirements for solar observations are significantly different from observations of sidereal sources and special measures are necessary to successfully carry out this type of observations. We describe the commissioning efforts that enable the use of two frequency bands, the 3-mm band (Band 3) and the 1.25-mm band (Band 6), for continuum interferometric-imaging observations of the Sun with ALMA. Examples of high-resolution synthesized images obtained using the newly commissioned modes during the solar-commissioning campaign held in December 2015 are presented. Although only 30 of the eventual 66 ALMA antennas were used for the campaign, the solar images synthesized from the ALMA commissioning data reveal new features of the solar atmosphere that demonstrate the potential power of ALMA solar observations. The ongoing expansion of ALMA and solar-commissioning efforts will continue to enable new and unique solar observing capabilities.

  6. Rotation and translation registration of bandlimited interferometric images using a chirp z-transform

    NASA Astrophysics Data System (ADS)

    Iacchetta, Alexander S.; Fienup, James R.; Leisawitz, David T.

    2016-07-01

    Image reconstruction algorithms for wide-field spatio-spectral interferometry require knowledge of registration parameters associated with low-resolution image measurements at various baseline orientations, such that the images can be registered to within the fine resolution of the final desired image. We have developed an image registration procedure that combines a nonlinear optimization algorithm with the sub-pixel precision of chirp z-transform resampling, particularly for rotation and translation, of bandlimited images with non-radially symmetric aberrations. We show the accuracy of this image registration technique on simulated images that have a complexity comparable to scenes observed experimentally with NASA's wide-field imaging interferometry testbed. Registration to within a tenth of a pixel for translation and within three arcminutes for rotation is demonstrated at the largest simulated noise levels.

  7. Using Regional GPS Network Atmospheric Models for Mitigating Errors in Interferometric Synthetic Aperture Radar (InSAR) Images

    NASA Astrophysics Data System (ADS)

    Reuveni, Y.; Bock, Y.; Tong, X.; Moore, A. W.

    2015-12-01

    Interferometric Synthetic Aperture Radar (InSAR) measurements provide valuable information for obtaining Earth surface deformation and topography at high spatial resolution for crustal deformation studies. Similar to Global Positioning System (GPS), InSAR phase measurements are affected by the Earth's ionospheric and tropospheric layers as the electromagnetic signals significantly refract while propagating through the different layers. While electromagnetic signals propagating through the neutral atmosphere are affected primarily by the pressure, temperature, and water vapor content of atmospheric gases, the propagation through the ionosphere is mainly affected by the number of free electrons along the signal path. Here, we present the use of dense regional GPS networks for extracting tropospheric zenith delays and ionospheric Total Electron Content (TEC) maps in order to reduce the noise levels in the phase measurement of the InSAR images. The results show significant reduction in the RMS values when simultaneously combining the two corrections, both at short time periods where no surface deformation is expected, and at longer periods, where imaging of crustal deformation, such as the ground subsidence and aseismic fault creep, is enhanced.

  8. The Space Infrared Interferometric Telescope (SPIRIT): High-resolution Imaging and Spectroscopy in the Far-infrared

    NASA Technical Reports Server (NTRS)

    Leisawitz, D,; Baker, G.; Barger, A.; Benford, D.; Blain, A; Boyle, R.; Broderick, R.; Budinoff, J.; Carpenter, J.; Caverly, R.; Chen, P.; Cooley, S.; Cottingham, C.; Crooke, J.; DiPietro, D.; Femiano, M.; Ferrer, A.; Fischer, J.; Gardner, J.; Hallock, L.; Harris, K.; Hartman, K.; Harwit, M.; Hillenbrand, L.; Hyde, T.

    2007-01-01

    We report results of a recently-completed study of SPIRIT, a candidate NASA Origins Probe. SPIRIT is a spatial and spectral interferometer with an operating wavelength range 25 - 400 microns. SPIRIT will provide sub-arcsecond resolution images and spectra with resolution R = 3000 in a 1 arcmin field of view to accomplish three primary scientific objectives: (1) Learn how planetary systems form from protostellar disks, and how they acquire their chemical organization; (2) Characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets form, and why some planets are ice giants and others are rocky; and (3) Learn how high-redshift galaxies formed and merged to form the present-day population of galaxies. Observations with SPIRIT will be complementary to those of the James Webb Space Telescope and the ground-based Atacama Large Millimeter Array. All three observatories could be operational contemporaneously. SPIRIT will pave the way to the 1 km maximum baseline interferometer known as the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS). In addition to the SPIRIT mission concept, this talk will emphasize the importance of dense u-v plane coverage and describe some of the practical considerations associated with alternative interferometric baseline sampling schemes.

  9. The Space Infrared Interferometric Telescope (SPIRIT): High-resolution Imaging and Spectroscopy in the Far-infrared

    NASA Technical Reports Server (NTRS)

    Leisawitz, D,; Baker, G.; Barger, A.; Benford, D.; Blain, A; Boyle, R.; Broderick, R.; Budinoff, J.; Carpenter, J.; Caverly, R.; hide

    2007-01-01

    We report results of a recently-completed study of SPIRIT, a candidate NASA Origins Probe. SPIRIT is a spatial and spectral interferometer with an operating wavelength range 25 - 400 microns. SPIRIT will provide sub-arcsecond resolution images and spectra with resolution R = 3000 in a 1 arcmin field of view to accomplish three primary scientific objectives: (1) Learn how planetary systems form from protostellar disks, and how they acquire their chemical organization; (2) Characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets form, and why some planets are ice giants and others are rocky; and (3) Learn how high-redshift galaxies formed and merged to form the present-day population of galaxies. Observations with SPIRIT will be complementary to those of the James Webb Space Telescope and the ground-based Atacama Large Millimeter Array. All three observatories could be operational contemporaneously. SPIRIT will pave the way to the 1 km maximum baseline interferometer known as the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS). In addition to the SPIRIT mission concept, this talk will emphasize the importance of dense u-v plane coverage and describe some of the practical considerations associated with alternative interferometric baseline sampling schemes.

  10. Optimization of Positioning of Interferometric Array Antennas Using Division Algorithm for Radio Astronomy Applications

    NASA Astrophysics Data System (ADS)

    Kiehbadroudinezhad, Shahideh; Valente, Daniela; Cada, Michael; Kamariah Noordin, Nor; Shahabi, Adib

    2017-10-01

    The Square Kilometre Array (SKA) ushers in the new generation of large radio telescopes that will work at wavelengths between meters and centimeters. In order to competitively design interferometric antenna arrays such as SKA, it is crucial to focus on the optimization of system performance. In this paper, we contribute to the solution by introducing a new optimization algorithm called Division Algorithm (DA). This algorithm finds the optimal positions of antennas to simultaneously maximize u–v coverage and decrease sidelobe level (SLL). The DA is able to optimize the configuration of the interferometric array in both snapshot and Earth rotation synthesis observations. To demonstrate its efficiency, the DA is applied to configure an optimum 30-element array for the Giant Metrewave Radio Telescope. The proposed algorithm is able to improve the overlapped samples parameter by about 4% and the unsampled cells parameter by about 12%, at snapshot observation, compared to the Genetic Algorithm (GA). DA is able to improve these two parameters for a 6-hr tracking observation as well. Finally, the proposed algorithm is compared with the GA for different source declination. Results show that the DA is able to decrease the SLL better than the GA.

  11. "Phase-Enhanced" 3D Snapshot ISAR Imaging and Interferometric SAR

    DTIC Science & Technology

    2009-12-28

    document when it is no longer needed. Massachusetts Institute of Technology Lincoln Laboratory ttPhase-Lnhanced,, 3D Snapshot ISAR Imaging and...inverse synthetie aperture radar ( ISAR ) images based on recent developments in high resolution spectral estimation theory. Because this technique requires...the radar sensor. This report develops a framework based on 3D snapshot imaging of sparse angle sectors of ISAR data, extending these results to 3D

  12. Application of a white-light interferometric measuring system as co-phasing the segmented primary mirrors of the high-aperture telescope

    NASA Astrophysics Data System (ADS)

    Song, Helun; Li, Huaqiang; Xian, Hao; Huang, Jian; Wang, Shengqian; Jiang, Wenhan

    2008-03-01

    For the optical system of the telescope, with the increase in telescope size, the manufacture of monolithic primary becomes increasingly difficult. Instead, the use of segmented mirrors, where many individual mirrors (the segments) work together to provide an image quality and an aperture equivalent to that of a large monolithic mirror, is considered a more appropriate strategy. But with the introduction of the large telescope mirror comprised of many individual segments, the problem of insuring a smooth continuous mirror surface (co-phased mirrors) becomes critical. One of the main problems is the measurement of the vertical displacement between the individual segments (piston error), for such mirrors, the segment vertical misalignment (piston error) between the segments must be reduced to a small fraction of the wavelength (<100nm) of the incoming light. The measurements become especially complicated when the piston error is in order of wavelength fractions. To meet the performance capabilities, a novel method for phasing the segmented mirrors optics system is described. The phasing method is based on a high-aperture Michelson interferometer. The use of an interferometric technique allows the measuring of segment misalignment during the daytime with high accuracy, which is a major design guideline. The innovation introduced in the optical design of the interferometer is the simultaneous use of monochromatic light and multiwavelength combination white-light source in a direct method for improving the central fringe identification in the white-light interferometric phasing system. With theoretic analysis, we find that this multiwavelength combination technique can greatly increase the visibility difference between the central fringe and its adjacent side fringes, and thus it offers an increased signal resolution. So make the central fringe identification become easier, and enhance the measure precision of the segment phasing error. Consequently, it is suitable for

  13. Interferometric Synthetic Aperture Radar Imaging of Ocean Surface Currents and Wavefields

    DTIC Science & Technology

    1990-06-01

    demonstrated. INSAR consists of a single conventional SAR augmented by an additional receiving antenna. The phase difference between the corresponding SAR image...receiving antenna. The phase difference between the correspond- ing SAR image scenes observed by the antennas provides an interferogram that is...Azimuthal Resolution ....................... 18 2. Phase History (stationary point target) ............. 19 3. Coherent Integration Time

  14. Interferometric hard x-ray phase contrast imaging at 204 nm grating period

    SciTech Connect

    Wen Han; Gomella, Andrew A.; Miao, Houxun; Lynch, Susanna K.; Wolfe, Douglas E.; Xiao Xianghui; Liu Chian; Morgan, Nicole

    2013-01-15

    We report on hard x-ray phase contrast imaging experiments using a grating interferometer of approximately 1/10th the grating period achieved in previous studies. We designed the gratings as a staircase array of multilayer stacks which are fabricated in a single thin film deposition process. We performed the experiments at 19 keV x-ray energy and 0.8 {mu}m pixel resolution. The small grating period resulted in clear separation of different diffraction orders and multiple images on the detector. A slitted beam was used to remove overlap of the images from the different diffraction orders. The phase contrast images showed detailed features as small as 10 {mu}m, and demonstrated the feasibility of high resolution x-ray phase contrast imaging with nanometer scale gratings.

  15. Interferometric hard x-ray phase contrast imaging at 204 nm grating period

    NASA Astrophysics Data System (ADS)

    Wen, Han; Wolfe, Douglas E.; Gomella, Andrew A.; Miao, Houxun; Xiao, Xianghui; Liu, Chian; Lynch, Susanna K.; Morgan, Nicole

    2013-01-01

    We report on hard x-ray phase contrast imaging experiments using a grating interferometer of approximately 1/10th the grating period achieved in previous studies. We designed the gratings as a staircase array of multilayer stacks which are fabricated in a single thin film deposition process. We performed the experiments at 19 keV x-ray energy and 0.8 μm pixel resolution. The small grating period resulted in clear separation of different diffraction orders and multiple images on the detector. A slitted beam was used to remove overlap of the images from the different diffraction orders. The phase contrast images showed detailed features as small as 10 μm, and demonstrated the feasibility of high resolution x-ray phase contrast imaging with nanometer scale gratings.

  16. Interferometric hard x-ray phase contrast imaging at 204 nm grating period.

    PubMed

    Wen, Han; Wolfe, Douglas E; Gomella, Andrew A; Miao, Houxun; Xiao, Xianghui; Liu, Chian; Lynch, Susanna K; Morgan, Nicole

    2013-01-01

    We report on hard x-ray phase contrast imaging experiments using a grating interferometer of approximately 1/10th the grating period achieved in previous studies. We designed the gratings as a staircase array of multilayer stacks which are fabricated in a single thin film deposition process. We performed the experiments at 19 keV x-ray energy and 0.8 μm pixel resolution. The small grating period resulted in clear separation of different diffraction orders and multiple images on the detector. A slitted beam was used to remove overlap of the images from the different diffraction orders. The phase contrast images showed detailed features as small as 10 μm, and demonstrated the feasibility of high resolution x-ray phase contrast imaging with nanometer scale gratings.

  17. The VLT Interferometer and its AMBER Instrument: Simulations of Interferometric Imaging in the Wide-Field Mode

    NASA Astrophysics Data System (ADS)

    Blöcker, T.; Hofmann, K.-H.; Przygodda, F.; Weigelt, G.

    We present computer simulations of interferometric imaging with the VLT interferometer and the AMBER instrument. These simulations include both the astrophysical modelling of a stellar object by radiative transfer calculations and the simulation of light propagation from the object to the detector (through atmosphere, telescopes, and the AMBER instrument), simulation of photon noise and detector read-out noise, and finally data processing of the interferograms. The results show the dependence of the visibility error bars on the following observational parameters: different seeing during the observation of object and reference star (Fried parameters r0,object and r0,ref. ranging between 0.9 m and 1.2 m), different residual tip-tilt error (δtt,object and δtt,ref. ranging between 0.1% and 20% of the Airy disk diameter), and object brightness (Kobject=3.5 mag to 13 mag, Kref.=3.5 mag). Exemplarily, we focus on stars in late stages of stellar evolution and study one of its key objects, the dusty supergiant IRC +10 420 that is rapidly evolving on human timescales. We show computer simulations of VLT interferometry of IRC +10 420 with two ATs (wide-field mode, i.e. without fiber optics spatial filters) and discuss whether the visibility accuracy is sufficient to distinguish between different theoretical model predictions.

  18. Active control of a balanced two-stage pendulum vibration isolation system and its application to laser interferometric gravity wave detectors

    SciTech Connect

    Veitch, P.J.; Robertson, N.A.; Cantley, C.A.; Hough, J. )

    1993-05-01

    The investigation of the servo control of the position of the bottom mass in a balanced two-stage pendulum vibration isolation system is reported. Experimental results for a simple prototype system and predictions based on a model presented in this paper are in good agreement. The application of such a system to a high-sensitivity laser interferometric gravity wave detector is discussed.

  19. Design of a dynamic biofilm imaging cell for white-light interferometric microscopy

    DOE PAGES

    Larimer, Curtis; Brann, Michelle; Suter, Jonathan D.; ...

    2017-05-10

    In microbiology research there is a strong need for next generation imaging and sensing instrumentation that will enable minimally invasive and label-free investigation of soft, hydrated structures such as in bacterial biofilms. White light interferometry (WLI) can provide high resolution images of surface topology without the use of fluorescent labels but is not typically used to image biofilms because there is insufficient refractive index contrast to induce reflection from the biofilm’s interface. The soft structure and water-like bulk properties of hydrated biofilms make them difficult to characterize in situ, especially in a non-destructive manner. In this report, we build onmore » our prior description of static biofilm imaging and describe the design of a dynamic imaging flow cell that enables monitoring the thickness and topology of live biofilms over time using a WLI microscope. The microfluidic system is specifically designed to create a reflective interface on the surface of biofilms while minimizing disruption of fragile structures. The imaging cell was also designed to accommodate limitations imposed by the depth of focus of the microscope’s objective lens. Example images of live biofilm samples are shown in order to illustrate the ability of the flow cell and WLI instrument to 1) support bacterial growth and biofilm development, 2) image biofilm structure that reflects growth in flow conditions, and 3) monitor biofilm development over time non-destructively. In future work, the apparatus described here will enable surface metrology measurements (roughness, surface area, etc.) of biofilms and may be used to observe changes in biofilm structure in response to changes in environmental conditions (e.g., flow velocity, availability of nutrients, and presence of biocides). Furthermore, this development will open new opportunities for the use of WLI in bioimaging.« less

  20. Speckle interferometric images of (216) Kleopatra from the Keck I Telescope

    NASA Astrophysics Data System (ADS)

    Hammergren, M.; Macintosh, B.; Gibbard, S.; Gavel, D.

    2000-10-01

    We present 0.05-arcsecond resolution near-IR images of the unusual main belt asteroid (216) Kleopatra, obtained via speckle interferometry with the 10-m Keck-I telescope in November 1999. The time series of 22 images cover nearly a full rotation, and clearly resolve the asteroid. The images reveal it to be a single, highly-elongated, dumbbell-shaped body, oriented about 30 degrees from pole-on during the time of our observations. We have performed Hapke photometric modeling of the asteroid's surface, and have constructed a three-dimensional shape model. The shape we have derived for this asteroid is nearly identical to the radar delay-Doppler reconstructions of Ostro et al. (Science 288, 836). While the Ostro et al. observations permit a higher spatial resolution in their modeling, our observations have the virtue of being real spatial images, thus providing independent confirmation of their shape model. Our shape model is also consistent with the stellar occultation results of Dunham (Sky and Telescope 83, 73) and pre-COSTAR HST images reported by Storrs et al. (Icarus 137, 260). Our images also allow us to search for albedo and color variations across the asteroid; no significant heterogeneity is seen. This research was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under contract W-7405-ENG-48.

  1. Interferometric microscopy of silicon photonic devices

    NASA Astrophysics Data System (ADS)

    Rabinovich, William S.; Mahon, Rita; Goetz, Peter G.; Pruessner, Marcel; Ferraro, Mike S.; Park, Doe; Fleet, Erin; DePrenger, Michael J.

    2015-02-01

    Silicon photonics provides the ability to construct complex photonic circuits that act on the amplitude and phase of multiple optical channels. Many applications of silicon photonics depend on maintenance of optical coherence among the various waveguides and structures on the chip. Other applications can depend on the modal structures of the waveguides. All these application require the ability to characterize the amplitude and phase of individual optical channels. Fourier imaging with high numerical aperture microscope objectives has been used to image the intensity of individual channels of photonic structures in both real and Fourier space. In other work, holographic imaging of multimode fibers has allowed modal decomposition. In this work we use interferometric microscopy to image the amplitude and phase of a variety of silicon photonic structures. These include a multimode interference splitter and a multimode waveguide under various excitation conditions.

  2. Imaging the bipolarity of myosin filaments with Interferometric Second Harmonic Generation microscopy.

    PubMed

    Rivard, Maxime; Couture, Charles-André; Miri, Amir K; Laliberté, Mathieu; Bertrand-Grenier, Antony; Mongeau, Luc; Légaré, François

    2013-01-01

    We report that combining interferometry with Second Harmonic Generation (SHG) microscopy provides valuable information about the relative orientation of noncentrosymmetric structures composing tissues. This is confirmed through the imaging of rat medial gastrocnemius muscle. The inteferometric Second Harmonic Generation (ISHG) images reveal that each side of the myosin filaments composing the A band of the sarcomere generates π phase shifted SHG signal which implies that the myosin proteins at each end of the filaments are oriented in opposite directions. This highlights the bipolar structural organization of the myosin filaments and shows that muscles can be considered as a periodically poled biological structure.

  3. High-resolution coherent backscatter interferometric radar images of equatorial spread F using Capon's method

    NASA Astrophysics Data System (ADS)

    Rodrigues, Fabiano S.; de Paula, Eurico R.; Zewdie, Gebreab K.

    2017-03-01

    We present results of Capon's method for estimation of in-beam images of ionospheric scattering structures observed by a small, low-power coherent backscatter interferometer. The radar interferometer operated in the equatorial site of São Luís, Brazil (2.59° S, 44.21° W, -2.35° dip latitude). We show numerical simulations that evaluate the performance of the Capon method for typical F region measurement conditions. Numerical simulations show that, despite the short baselines of the São Luís radar, the Capon technique is capable of distinguishing localized features with kilometric scale sizes (in the zonal direction) at F region heights. Following the simulations, we applied the Capon algorithm to actual measurements made by the São Luís interferometer during a typical equatorial spread F (ESF) event. As indicated by the simulations, the Capon method produced images that were better resolved than those produced by the Fourier method. The Capon images show narrow (a few kilometers wide) scattering channels associated with ESF plumes and scattering regions spaced by only a few tens of kilometers in the zonal direction. The images are also capable of resolving bifurcations and the C shape of scattering structures.

  4. Interferometric examination of the vibration modes on stretchable plastic membrane imaging mirrors

    NASA Astrophysics Data System (ADS)

    Waddell, Peter; Stickland, Mathew; Mason, Steven; McKay, Stuart; Mair, Leslie S.

    1996-12-01

    The paper describes a simple interferometer which has been used to visualize the airborne noise induced, low frequency, very small amplitude, vibrations on thin plastic membrane mirrors. Plastic membrane concave imaging mirrors are the patented invention of the first named author and have been the subject of papers since 1983. The mirrors have already been used for inexpensive large aperture flow visualization systems and the transfer of images in holography. The mirrors are being used currently for high definition, natural color large aperture stereoscopy and self focused real imaging with no spectator glasses, i.e., 3D imaging systems. As the mirror diameter increases for the same type and thickness of membrane material then the fundamental resonant frequency decreases. For very large diameters the mirrors become susceptible to aerial noise of a few Hertz, this being equal to the fundamental resonant frequency. For the small mirror tested for this paper, the fundamental resonance was approximately 600 Hz. The mirror was, however, continually vibrating due to aerial room noise frequencies of between 1 Hz and 20 Hz. No proper nodal patterns can be seen, these only occur at frequencies above the fundamental. The vibrations are extremely small, requiring an interferometer to visualize and record amplitude and frequency. The vibration energy can be destroyed by several techniques. The mirrors have already been used for long exposure white light reflection holograms, effectively no vibrations at all on the mirror surface, achieved by destroying the vibration energy.

  5. Systematic study of synthetic aperture processing in interferometric three-dimensional imaging spectrometry

    NASA Astrophysics Data System (ADS)

    Obara, Masaki; Yoshimori, Kyu

    2017-02-01

    We have recently proposed a method of obtaining many spectral components of complex holograms under incoherent illumination. This method is based on the measurement of five-dimensional interferograms and signal processing including synthetic aperture processing. In this paper, we report the relationship between the selection rules used for synthetic aperture processing and the generated volume interferograms. As a result of our systematic study, we find six types of selection rule and generate volume interferograms that are the most important and basic. We discuss the benefits of using each selection rule and the three-dimensional (3D) imaging properties of retrieval imaging obtained from these volume interferograms. A new noise reduction method based on these six types of selection rules is also proposed.

  6. High-resolution interferometric imaging of stress propagation in pediatric and adult skulls

    NASA Astrophysics Data System (ADS)

    Conerty, Michelle D.; Castracane, James; Clow, Lawrence P., Jr.; Koltai, Peter J.; Mouzakes, Jason

    1997-05-01

    Variations based on bone growth and development make stress and fracture propagation differ greatly in pediatric skulls as compared to adult skulls. Differentiating the stress propagation between the pediatric and adult skulls can improve diagnostic prediction when presented with direct frontal impact on a pediatric skull, a fairly common occurrence in the clinical environment. Critical diagnostic information can be learned from an in depth study of stress propagation as a function of impact force at critical locations on the periorbital region of the human skull. The Division of Pediatric Otolaryngology at Albany Medical College and InterScience, Inc. are utilizing electronic speckle pattern interferometry detection (ESPI) and high resolution imaging to evaluate and compare stress propagation in pediatric and adult skulls. A dual detection ESPI system was developed which integrates a medium resolution (2/3') CCD capable of real-time image processing, with a high resolution, megapixel detector capable of limited real time acquisition and image processing in software. Options to allow for high speed detection include integrating a custom, high performance image intensifier with the megapixel detector leg to be used as a high speed gate. The dual optical layout will allow for continuous and pulsed ESPI evaluation of calibrated impacts at specific landmarks on the skull. The goal of this work is to produce a full quantitative analysis of the stress propagation in pediatric versus adult skulls for a better understanding of bone dynamics. The work presented below concentrates on the development of the dual detection ESPI system and initial results achieved with an adult cadaver skull.

  7. Three-dimensional interferometric inverse synthetic aperture radar imaging of maneuvering target based on the joint cross modified Wigner-Ville distribution

    NASA Astrophysics Data System (ADS)

    Lv, Qian; Su, Tao; Zheng, Jibin; Zhang, Jiancheng

    2016-01-01

    Inverse synthetic aperture radar (ISAR) can achieve high-resolution two-dimensional images of maneuvering targets. However, due to the indeterminate relative motion between radar and target, ISAR imaging does not provide the three-dimensional (3-D) position information of a target and suffers from great difficulty in target recognition. To tackle this issue, a 3-D interferometric ISAR (InISAR) imaging algorithm based on the joint cross modified Wigner-Ville distribution (MWVD) is presented to form 3-D images of maneuvering targets. First, we form two orthogonal interferometric baselines with three receiving antennas to establish an InISAR imaging system. Second, after the uniform range alignment and phase adjustment, the joint cross MWVD is used for all range cell of each antenna pair to generate the separation of the scatterer as well as preserve the phase that contains position information of the scatterer. At last, the 3-D images of the target can be directly reconstructed from the distribution. Simulation results demonstrate the validity of the proposal.

  8. Study of a passive companion microsatellite to the SAOCOM-1B satellite of Argentina, for bistatic and interferometric SAR applications

    NASA Astrophysics Data System (ADS)

    Barbier, Christian; Derauw, Dominique; Orban, Anne; Davidson, Malcolm W. J.

    2014-10-01

    We report the results of a preparatory study aimed at exploring candidate applications that could benefit from a passive micro-satellite accompanying the L-band SAOCOM-1B satellite of Argentina, and to carry out a limited demonstration, based on data acquired during ESA airborne campaigns, of selected applications. In a first step of the study, the potential applications were identified and prioritized based on the mission context and strategic applications, scientific need, and feasibility. The next step of the study was to carry out some demonstrations using data sets acquired during the BioSAR 2007-2009, TropiSAR 2009 and IceSAR 2007 campaigns. A P-band InSAR digital elevation model was generated from BioSAR 2007 data. Time-series of interferometric coherence maps were obtained as a tool for change detection and monitoring. PolInSAR processing was carried out on BioSAR 2007 and IceSAR data.

  9. Computer simulations of interferometric imaging with the Very Large Telescope Interferometer and its Astronomical Multibeam Recombiner instrument

    NASA Astrophysics Data System (ADS)

    Przygodda, Frank; Bloecker, Thomas; Hofmann, Karl-Heinz; Weigelt, Gerd

    2001-05-01

    We present computer simulations of interferometric imaging with the Very Large Telescope Interferometer (VLTI) of the European Southern Observatory and the Astronomical Multibeam Recombiner (AMBER) phase-closure instrument. These simulations include both the astrophysical modeling of a stellar object by radiative-transfer calculations and the simulation of light propagation from the object to the detector (through atmosphere, telescopes, and the AMBER instrument), simulation of photon noise and detector readout noise, and finally data processing of the interferograms. The results show the dependence of the visibility error bars on the following observational parameters: different seeing during the observation of object and reference star (Fried parameters r0,object and r0,ref ranging between 0.9 and 1.2 m), different residual tip-tilt error ((delta) tt,object and (delta) tt,ref ranging between 0.1% and 20% of the Airy-disk diameter), and object brightness (Kobject equals 0.7 to 10.2 mag, Kref equals 0.7 mag). As an example, we focus on stars in late stages of stellar evolution and study one of the key objects of that kind, the dusty super-giant IRC + 10420, which is rapidly evolving on human time scales. We show computer simulations of VLT interferometer (visibility and phase-closure measurements) of IRC + 10420 with two and three auxiliary telescopes (in AMBER wide-field mode, i.e., without fiber optic spatial filters) and discuss whether the visibility accuracy is sufficient to distinguish between different theoretical model predictions.

  10. WIDE-FIELD WIDE-BAND INTERFEROMETRIC IMAGING: THE WB A-PROJECTION AND HYBRID ALGORITHMS

    SciTech Connect

    Bhatnagar, S.; Rau, U.; Golap, K. E-mail: rurvashi@nrao.edu

    2013-06-20

    Variations of the antenna primary beam (PB) pattern as a function of time, frequency, and polarization form one of the dominant direction-dependent effects at most radio frequency bands. These gains may also vary from antenna to antenna. The A-Projection algorithm, published earlier, accounts for the effects of the narrow-band antenna PB in full polarization. In this paper, we present the wide-band A-Projection algorithm (WB A-Projection) to include the effects of wide bandwidth in the A-term itself and show that the resulting algorithm simultaneously corrects for the time, frequency, and polarization dependence of the PB. We discuss the combination of the WB A-Projection and the multi-term multi-frequency synthesis (MT-MFS) algorithm for simultaneous mapping of the sky brightness distribution and the spectral index distribution across a wide field of view. We also discuss the use of the narrow-band A-Projection algorithm in hybrid imaging schemes that account for the frequency dependence of the PB in the image domain.

  11. Wide-field wide-band Interferometric Imaging: The WB A-Projection and Hybrid Algorithms

    NASA Astrophysics Data System (ADS)

    Bhatnagar, S.; Rau, U.; Golap, K.

    2013-06-01

    Variations of the antenna primary beam (PB) pattern as a function of time, frequency, and polarization form one of the dominant direction-dependent effects at most radio frequency bands. These gains may also vary from antenna to antenna. The A-Projection algorithm, published earlier, accounts for the effects of the narrow-band antenna PB in full polarization. In this paper, we present the wide-band A-Projection algorithm (WB A-Projection) to include the effects of wide bandwidth in the A-term itself and show that the resulting algorithm simultaneously corrects for the time, frequency, and polarization dependence of the PB. We discuss the combination of the WB A-Projection and the multi-term multi-frequency synthesis (MT-MFS) algorithm for simultaneous mapping of the sky brightness distribution and the spectral index distribution across a wide field of view. We also discuss the use of the narrow-band A-Projection algorithm in hybrid imaging schemes that account for the frequency dependence of the PB in the image domain.

  12. Resist evauation at 50 nm in the EUV using interferometric spatial-frequency-doubled imaging

    NASA Astrophysics Data System (ADS)

    Shumway, Michael D.; Naulleau, Patrick P.; Goldberg, Kenneth A.; Snow, Eric L.; Bokor, Jeffrey

    2003-06-01

    By using a spatial frequency doubling method, our 10x Schwarzschild optic can print high-contrast features at 50 nm with low line-edge roughness (LER). In this paper, we also present new techniques for evaluating photoresist at EUV wavelengths using our system. One method is used to determine the ultimate resolution of a resist through linewidth vs. dose measurements. Another is to investigate line-edge roughness properties by varying the aerial image contrast of a pattern. A novel filtering method is proposed that would allow multiple contrasts to be printed in a single exposure. This is achieved by varying the duty cycle and line/space transmission levels of the object grating. Since this is a single exposure technique it would allow for mroe controlled contrast tests when evaluating resists.

  13. Real Time Optical Interferometric Image Addition and Subtraction by Wave Polarization.

    DTIC Science & Technology

    1981-10-15

    anal’ vs is of thei r experimental res u Its w-,i th reg: od to th)e var-ious opti cal components such as the lens and 1Wol lastor nri sm,. havo been...lens C. It was found that the ;.O iznrs F. ind P,, ...ore no! required. In that case, each input irane I t’V,( .) 1Vll v seurated images at the output...ti u sd n t - r a 7C I Ia t -!On , h2 6nIf 32 .3 nmii; t he i (-k tie s s o ft the i-e 1as t o 1 1;1 1110 ~ mjlfe cf the Wol laston nri -mi

  14. An accelerated splitting algorithm for radio-interferometric imaging: when natural and uniform weighting meet

    NASA Astrophysics Data System (ADS)

    Onose, Alexandru; Dabbech, Arwa; Wiaux, Yves

    2017-07-01

    Next-generation radio interferometers, like the Square Kilometre Array, will acquire large amounts of data with the goal of improving the size and sensitivity of the reconstructed images by orders of magnitude. The efficient processing of large-scale data sets is of great importance. We propose an acceleration strategy for a recently proposed primal-dual distributed algorithm. A preconditioning approach can incorporate into the algorithmic structure both the sampling density of the measured visibilities and the noise statistics. Using the sampling density information greatly accelerates the convergence speed, especially for highly non-uniform sampling patterns, while relying on the correct noise statistics optimizes the sensitivity of the reconstruction. In connection to clean, our approach can be seen as including in the same algorithmic structure both natural and uniform weighting, thereby simultaneously optimizing both the resolution and the sensitivity. The method relies on a new non-Euclidean proximity operator for the data fidelity term, that generalizes the projection on to the ℓ2 ball where the noise lives for naturally weighted data, to the projection on to a generalized ellipsoid incorporating sampling density information through uniform weighting. Importantly, this non-Euclidean modification is only an acceleration strategy to solve the convex imaging problem with data fidelity dictated only by noise statistics. We show through simulations with realistic sampling patterns the acceleration obtained using the preconditioning. We also investigate the algorithm performance for the reconstruction of the 3C129 radio galaxy from real visibilities and compare with multiscale clean, showing better sensitivity and resolution. Our matlab code is available online on GitHub.

  15. Low-Coherence Interferometric Fiber-Optic Sensors with Potential Applications as Biosensors

    PubMed Central

    Hirsch, Marzena; Majchrowicz, Daria; Wierzba, Paweł; Weber, Matthieu; Bechelany, Mikhael; Jędrzejewska-Szczerska, Małgorzata

    2017-01-01

    Fiber-optic Fabry-Pérot interferometers (FPI) can be applied as optical sensors, and excellent measurement sensitivity can be obtained by fine-tuning the interferometer design. In this work, we evaluate the ability of selected dielectric thin films to optimize the reflectivity of the Fabry-Pérot cavity. The spectral reflectance and transmittance of dielectric films made of titanium dioxide (TiO2) and aluminum oxide (Al2O3) with thicknesses from 30 to 220 nm have been evaluated numerically and compared. TiO2 films were found to be the most promising candidates for the tuning of FPI reflectivity. In order to verify and illustrate the results of modelling, TiO2 films with the thickness of 80 nm have been deposited on the tip of a single-mode optical fiber by atomic layer deposition (ALD). The thickness, the structure, and the chemical properties of the films have been determined. The ability of the selected TiO2 films to modify the reflectivity of the Fabry-Pérot cavity, to provide protection of the fibers from aggressive environments, and to create multi-cavity interferometric sensors in FPI has then been studied. The presented sensor exhibits an ability to measure refractive index in the range close to that of silica glass fiber, where sensors without reflective films do not work, as was demonstrated by the measurement of the refractive index of benzene. This opens up the prospects of applying the investigated sensor in biosensing, which we confirmed by measuring the refractive index of hemoglobin and glucose. PMID:28134855

  16. Low-Coherence Interferometric Fiber-Optic Sensors with Potential Applications as Biosensors.

    PubMed

    Hirsch, Marzena; Majchrowicz, Daria; Wierzba, Paweł; Weber, Matthieu; Bechelany, Mikhael; Jędrzejewska-Szczerska, Małgorzata

    2017-01-28

    Fiber-optic Fabry-Pérot interferometers (FPI) can be applied as optical sensors, and excellent measurement sensitivity can be obtained by fine-tuning the interferometer design. In this work, we evaluate the ability of selected dielectric thin films to optimize the reflectivity of the Fabry-Pérot cavity. The spectral reflectance and transmittance of dielectric films made of titanium dioxide (TiO₂) and aluminum oxide (Al₂O₃) with thicknesses from 30 to 220 nm have been evaluated numerically and compared. TiO₂ films were found to be the most promising candidates for the tuning of FPI reflectivity. In order to verify and illustrate the results of modelling, TiO₂ films with the thickness of 80 nm have been deposited on the tip of a single-mode optical fiber by atomic layer deposition (ALD). The thickness, the structure, and the chemical properties of the films have been determined. The ability of the selected TiO₂ films to modify the reflectivity of the Fabry-Pérot cavity, to provide protection of the fibers from aggressive environments, and to create multi-cavity interferometric sensors in FPI has then been studied. The presented sensor exhibits an ability to measure refractive index in the range close to that of silica glass fiber, where sensors without reflective films do not work, as was demonstrated by the measurement of the refractive index of benzene. This opens up the prospects of applying the investigated sensor in biosensing, which we confirmed by measuring the refractive index of hemoglobin and glucose.

  17. Applications of Radar Interferometric Techniques to Assess Natural Hazards and their Controlling Factors

    NASA Astrophysics Data System (ADS)

    Sultan, M.; Becker, R.; Gebremichael, E.; Othman, A.; Emil, M.; Ahmed, M.; Elkadiri, R.; Pankratz, H. G.; Chouinard, K.

    2015-12-01

    Radar interferometric techniques including Persistent Scatterer (PS), Small BAseline Subset (SBAS), and two and three pass (differential interferometry) methods were applied to Synthetic Aperture Radar (SAR) datasets. These include the European Space Agency (ESA) ERS-1, ERS-2, Environmental satellite (Envisat), and Phased Array type L-band Synthetic Aperture Radar (PALSAR) to conduct the following: (1) map the spatial distribution of land deformation associated with a wide range of geologic settings, (2) quantify the rates of the observed land deformation, and (3) identify the factors controlling the observed deformation. The research topics/areas include: (1) subsidence associated with sediment compaction in a Delta setting (Nile Delta, Egypt), (2) deformation in a rifting setting (Red Sea rifting along the Red Sea coastal zone and proximal basement outcrops in Egypt and Saudi Arabia), (3) deformation associated with salt dome intrusion and the dissolution of sabkha deposits (Jazan area in Saudi Arabia), (4) mass transport associated with debris flows (Jazan area in Saudi Arabia), and (5) deformation preceding, contemporaneous with, or following large earthquakes (in Nepal; magnitude: 7.8; date: April, 25, 2015) and medium earthquakes (in Harrat Lunayyir volcanic field, central Saudi Arabia; magnitude: 5.7; date: May 19, 2009). The identification of the factor(s) controlling the observed deformation was attained through spatial correlation of extracted radar velocities with relevant temporal and static ground based and remotely sensed geological and cultural data sets (e.g., lithology, structure, precipitation, land use, and earthquake location, magnitude, and focal mechanism) in a Geographical Information System (GIS) environment.

  18. Spatial and Temporal Characteristics of Land Deformation in Northern Saudi Arabia: Inferences from Radar Interferometric Applications

    NASA Astrophysics Data System (ADS)

    Othman, A.; Sultan, M.; Gebremichael, E.; Sefry, S.; Yanar, R.; Alharbi, H.; Albalawi, S.; Emil, M. K.; Pankratz, H. G.

    2016-12-01

    Over the past two decades, land deformation phenomena and related losses in public and private property were reported from the northern part of the Kingdom of Saudi Arabia in Al Jowf region (100,212 km²; from lat: 29.25°N to 30.90°N, from long: 37.60°E to 40.70°E). We applied an integrated approach (geotechnical, geology, remote sensing, geodesy, hydrogeology, and GIS) to identify areas affected by these phenomena, quantify the nature and magnitude of deformation, investigate the factors controlling the deformation, and recommend solutions for these problems. We applied a three-fold approach in three different areas (Alisawiyah, Wadi Alsarhan, and Sakaka areas) to accomplish the following: (1) assess the spatial distribution of land deformation and quantify deformation rates using InSAR methods Persistent Scatterer Interferometry (PSI) and Small BAseline Subsets (SBAS); (2) generate a GIS database to encompass all relevant data and derived products (e.g., remote sensing, geology, geotechnical, GPS, groundwater extraction rates, distribution of urban areas, etc.), and (3) correlate findings from the InSAR exercise with relevant spatial and temporal datasets in search of causal effects. Findings revealed the following: (1) high and consistent subsidence rates (5 to 13 mm/yr) from multiple interferometric techniques; (2) subsided areas correlated largely with the distribution of irrigated agricultural land over alluvial and unconfined aquifers (e.g., Tawil and Jauf aquifers), areas characterized by high and a progressive increase in groundwater extraction (1.2 bcm/yr) as evidenced from the satellite-based temporal distribution of irrigated lands (area irrigated lands: 1998: 37,737 ha; 2013: 70,869 ha); (3) high subsidence rates ( 8 mm/yr) were also detected over urban areas (e.g., Sakaka, Dumat Aljandal, and Tubarjal ), subsidence being caused by disposal of wastewater in the subsurface leading to rise in water tables, dissolution of substrate rocks/sediments (e

  19. Interferometric star tracking.

    PubMed

    Decou, A B

    1974-02-01

    A new star-tracking technique based on interferometry is described and analyzed in detail. A heuristic comparison is made with traditional star-tracking methods that demonstrates several advantages in the interferometric approach for very high accuracy systems. A detailed error analysis is performed on several versions of the system that use all solid-state detection. One such system is shown to have a potential accuracy of +/-0.01 sec of arc using a small optical system and state-of-the-art components. Applications of the new system in large orbiting astronomical observatories and deep space laser communications systems are also discussed.

  20. Millimeter-wave interferometric SAR and polarimetry

    NASA Astrophysics Data System (ADS)

    Boehmsdorff, Stephan; Essen, Helmut; Schimpf, Hartmuf; Wahlen, Alfred

    1998-07-01

    Using synthetic aperture radars with appropriate signal processing algorithms is a recognized technique for remote sensing applications. A wide spectrum of radar frequencies is used and a high degree of sophistication implies polarimetric and further multichannel approaches. Each frequency band used, exhibits special sensitivities to features of the earth's surface or man-made targets. This is mostly due to the coupling of the electromagnetic waves to backscattering geometries which are related to the radarwavelength. A part of the spectrum which has been covered not very intensely is the millimeterwave region. This may be mostly due to the relatively high atmospheric absorption at millimeterwaves which obstructs the use of such sensors for long range applications. On the other hand for military applications IR-imaging sensors are widely used which suffer even more from adverse transmission properties of the atmosphere. Application of multichannel techniques as polarimetry, multifrequency techniques and interferometry are also done with more ease due to compactness of the hardware and simplicity of processing. As there exist no data which would allow to investigate the potential of multifrequency polarimetric and interferometric mmW-SAR the Millimeterwave Experimental Multifrequency Polarimetric High Resolution Interferometric Imaging System was installed into an aircraft C-160 `Transall' to gather respective data over different land scenarios. The off-line evaluation of the radar data starts with off-line track, calibration and reformatting procedures. Afterwards synthetic aperture processing is applied to these data to generate radar images for co- and cross-polarization at 35 GHz and 94 GHz. As already mentioned above, SAR-processing at millimeterwavelengths requires a considerable lower amount of sophistication in comparison with algorithms applied at lower radar-frequencies. This can mainly be attributed to the short aperture length at mm-wave frequencies

  1. Interferometric phase microscopy of red blood cells

    NASA Astrophysics Data System (ADS)

    Xue, Liang; Sun, Nan; Tang, Xian; Wang, Yin; Wang, Shouyu

    2013-12-01

    Quantitative phase imaging of cells with high accuracy in a completely noninvasive manner is a challenging task. To provide a proper solution to this important need, interferometric phase microscopy is described which relies on the off-axis interferometry, confocal microscopy and high-speed image capture technology. Phase retrieval from the single interferogram is done by algorithms based on the fast Fourier transform, traditional Hilbert transform and two-step Hilbert transform, respectively. Furthermore, a phase aberrations compensation approach is applied to correct the phase distribution of the red blood cells obtained via the three methods mentioned before without the pre-known knowledge for removing the wave front curvature introduced by the microscope objectives, off-axis imaging, etc., which otherwise hinders the phase reconstruction. The improved results reveal the better inner structures of the red blood cells. The development of quantitative phase imaging technique is shedding light on their future directions and applications for basic and clinical research.

  2. Nonlinear interferometric vibrational imaging

    NASA Technical Reports Server (NTRS)

    Boppart, Stephen A. (Inventor); Marks, Daniel L. (Inventor)

    2009-01-01

    A method of examining a sample, which includes: exposing a reference to a first set of electromagnetic radiation, to form a second set of electromagnetic radiation scattered from the reference; exposing a sample to a third set of electromagnetic radiation to form a fourth set of electromagnetic radiation scattered from the sample; and interfering the second set of electromagnetic radiation and the fourth set of electromagnetic radiation. The first set and the third set of electromagnetic radiation are generated from a source; at least a portion of the second set of electromagnetic radiation is of a frequency different from that of the first set of electromagnetic radiation; and at least a portion of the fourth set of electromagnetic radiation is of a frequency different from that of the third set of electromagnetic radiation.

  3. Interferometric Fiber Optic Sensors

    PubMed Central

    Lee, Byeong Ha; Kim, Young Ho; Park, Kwan Seob; Eom, Joo Beom; Kim, Myoung Jin; Rho, Byung Sup; Choi, Hae Young

    2012-01-01

    Fiber optic interferometers to sense various physical parameters including temperature, strain, pressure, and refractive index have been widely investigated. They can be categorized into four types: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac. In this paper, each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields. Some specific examples of recently reported interferometeric sensor technologies are presented in detail to show their large potential in practical applications. Some of the simple to fabricate but exceedingly effective Fabry-Perot interferometers, implemented in both extrinsic and intrinsic structures, are discussed. Also, a wide variety of Mach-Zehnder and Michelson interferometric sensors based on photonic crystal fibers are introduced along with their remarkable sensing performances. Finally, the simultaneous multi-parameter sensing capability of a pair of long period fiber grating (LPG) is presented in two types of structures; one is the Mach-Zehnder interferometer formed in a double cladding fiber and the other is the highly sensitive Sagnac interferometer cascaded with an LPG pair. PMID:22736961

  4. Interferometric fiber optic sensors.

    PubMed

    Lee, Byeong Ha; Kim, Young Ho; Park, Kwan Seob; Eom, Joo Beom; Kim, Myoung Jin; Rho, Byung Sup; Choi, Hae Young

    2012-01-01

    Fiber optic interferometers to sense various physical parameters including temperature, strain, pressure, and refractive index have been widely investigated. They can be categorized into four types: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac. In this paper, each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields. Some specific examples of recently reported interferometeric sensor technologies are presented in detail to show their large potential in practical applications. Some of the simple to fabricate but exceedingly effective Fabry-Perot interferometers, implemented in both extrinsic and intrinsic structures, are discussed. Also, a wide variety of Mach-Zehnder and Michelson interferometric sensors based on photonic crystal fibers are introduced along with their remarkable sensing performances. Finally, the simultaneous multi-parameter sensing capability of a pair of long period fiber grating (LPG) is presented in two types of structures; one is the Mach-Zehnder interferometer formed in a double cladding fiber and the other is the highly sensitive Sagnac interferometer cascaded with an LPG pair.

  5. Radar Interferometric Applications for a Better Understanding of the Distribution, Controlling Factors, and Precursors of Large Earthquakes in Turkey

    NASA Astrophysics Data System (ADS)

    Emil, M.; Sultan, M.; Fawzy, D. E.; Ahmed, M. E.; Chouinard, K.

    2012-12-01

    We are analyzing ERS-1 and ERS-2 and ENVISAT data to measure the spatial and temporal variations in three tectonically active areas near Izmit, Duzce and Van provinces in Turkey. We are using ERS-1 and ERS-2 data sets, which provide a longer time period of coverage (1992 to 2001). In addition, we will extend this forward to the present with ENVISAT radar data. The proposed activities can potentially provide predictive tools that can identify precursors to earthquakes and hence develop procedures to identify areas at risk. We are using radar interferometric techniques that have the ability of detecting deformation on the order of millimeters in scale over relatively large areas. We are applying the persistent scatterer and the small baseline subset (SBAS) techniques. A four fold exercise is being conducted: (1) extraction of land deformation rates and patterns from radar interferometry, (2) comparison and calibration of extracted rates to those extracted from existing geodetic ground stations, (3) identification of the natural factors (e.g., displacement along one or more faults) that are largely responsible for the observed deformation patterns, (4) utilizing the extracted deformation rates and/or patterns to identify areas prone to earthquake development in the near future, and (5) utilizing the extracted deformation rates or patterns to identify the areal extent of the domains affected by the earthquakes and the magnitude of the deformation following the earthquakes. The conditions in Turkey are typical of many of the world's areas that are witnessing continent to continent collisions. To date, applications similar to those advocated here for the assessment of ongoing land deformation in such areas and for identifying and characterizing land deformation as potential precursors to earthquakes have not been fully explored. Thus, the broader impact of this work lies in a successful demonstration of the advocated procedures in the study area which will invite similar

  6. New compact-design interferometer-based spectral imaging system for biomedical applications

    NASA Astrophysics Data System (ADS)

    Lavi, Mosik; Milman, Uri; Cabib, Dario; Garini, Yuval; Gil, Amir; Juta, Ton; Adel, Michael E.

    1998-06-01

    A common path interferometric element introduced in the optical path of an imaging device is a well documented method to perform multidimensional spectroscopy. Recent design modifications however have provided significant improvements including enhanced spectral resolution and optical throughput, reduced acquisition time, as well as reduced instrument weight and volume. The new design will be reviewed in addition to its impact on three applications: spectral karyotyping, spectral imaging of the human ocular fundus and remote sensing of water reservoirs.

  7. Performance modeling of a passive interferometric millimeter-wave sensor

    NASA Astrophysics Data System (ADS)

    Jacobs, Eddie L.; Furxhi, Orges

    2009-05-01

    This paper describes the modeling of human task performance using a passive interferometric millimeter wave (MMW) imaging sensor. The model is based on a previous model developed for concealed weapon identification using an active terahertz imager. Both models leverage the task performance modeling approach developed by the US Army Night Vision and Electronic Sensors Directorate. Key developments for this model include modeling of the effects of an interferometric antenna array, including sparse arrays, and a novel optical upconversion and processing stage being developed by the University of Delaware. Sparse interferometric arrays do not fully sample the spatial frequency extent of the image and as a result, can have degraded spatial frequency response over a fully populated array. The spatial frequency response of the sparse array can have a dramatic effect on image quality. Image quality is empirically related to task performance through the use of perception experiments. Possible applications of this model include system trade studies, concealed weapon identification, and navigation in fog and brown out conditions.

  8. Techniques and Tools for Estimating Ionospheric Effects in Interferometric and Polarimetric SAR Data

    NASA Technical Reports Server (NTRS)

    Rosen, P.; Lavalle, M.; Pi, X.; Buckley, S.; Szeliga, W.; Zebker, H.; Gurrola, E.

    2011-01-01

    The InSAR Scientific Computing Environment (ISCE) is a flexible, extensible software tool designed for the end-to-end processing and analysis of synthetic aperture radar data. ISCE inherits the core of the ROI_PAC interferometric tool, but contains improvements at all levels of the radar processing chain, including a modular and extensible architecture, new focusing approach, better geocoding of the data, handling of multi-polarization data, radiometric calibration, and estimation and correction of ionospheric effects. In this paper we describe the characteristics of ISCE with emphasis on the ionospheric modules. To detect ionospheric anomalies, ISCE implements the Faraday rotation method using quadpolarimetric images, and the split-spectrum technique using interferometric single-, dual- and quad-polarimetric images. The ability to generate co-registered time series of quad-polarimetric images makes ISCE also an ideal tool to be used for polarimetric-interferometric radar applications.

  9. Techniques and Tools for Estimating Ionospheric Effects in Interferometric and Polarimetric SAR Data

    NASA Technical Reports Server (NTRS)

    Rosen, P.; Lavalle, M.; Pi, X.; Buckley, S.; Szeliga, W.; Zebker, H.; Gurrola, E.

    2011-01-01

    The InSAR Scientific Computing Environment (ISCE) is a flexible, extensible software tool designed for the end-to-end processing and analysis of synthetic aperture radar data. ISCE inherits the core of the ROI_PAC interferometric tool, but contains improvements at all levels of the radar processing chain, including a modular and extensible architecture, new focusing approach, better geocoding of the data, handling of multi-polarization data, radiometric calibration, and estimation and correction of ionospheric effects. In this paper we describe the characteristics of ISCE with emphasis on the ionospheric modules. To detect ionospheric anomalies, ISCE implements the Faraday rotation method using quadpolarimetric images, and the split-spectrum technique using interferometric single-, dual- and quad-polarimetric images. The ability to generate co-registered time series of quad-polarimetric images makes ISCE also an ideal tool to be used for polarimetric-interferometric radar applications.

  10. Twin core photonic crystal fiber for in-line Mach-Zehnder interferometric sensing applications.

    PubMed

    Kim, Bongkyun; Kim, Tae-Hoon; Cui, Long; Chung, Youngjoo

    2009-08-31

    We will discuss fabrication of twin core photonic crystal fiber (TC-PCF) using the stack-and-draw method and its application for in-line Mach-Zehnder interferometers. The small difference in the effective indexes of the two core modes leads to interference fringes and the birefringence of the twin cores results in polarization-dependent fringe spacing. The strain sensitivity was negative and wavelength-dependent. A novel intensity-based bend sensor is also demonstrated with bend-induced spatial fringe shift. High air filling fraction of fabricated TC-PCF cladding provides immunity to bend-induced intensity fluctuation.

  11. Application of Polarimetric-Interferometric Phase Coherence Optimization (PIPCO) Procedure to SIR-C/X-SAR Tien-Shan Tracks 122.20(94 Oct. 08)/154.20(94 Oct. 09) Repeat-Orbit C/L-Band Pol-D-InSAR Imag

    NASA Technical Reports Server (NTRS)

    Boerner, W. M.; Mott, H.; Verdi, J.; Darizhapov, D.; Dorjiev, B.; Tsybjito, T.; Korsunov, V.; Tatchkov, G.; Bashkuyev, Y.; Cloude, S.; hide

    1998-01-01

    During the past decade, Radar Polarimetry has established itself as a mature science and advanced technology in high resolution POL-SAR imaging, image target characterization and selective image feature extraction.

  12. Application of Polarimetric-Interferometric Phase Coherence Optimization (PIPCO) Procedure to SIR-C/X-SAR Tien-Shan Tracks 122.20(94 Oct. 08)/154.20(94 Oct. 09) Repeat-Orbit C/L-Band Pol-D-InSAR Imag

    NASA Technical Reports Server (NTRS)

    Boerner, W. M.; Mott, H.; Verdi, J.; Darizhapov, D.; Dorjiev, B.; Tsybjito, T.; Korsunov, V.; Tatchkov, G.; Bashkuyev, Y.; Cloude, S.; Papathanassiou, K.; Pottier, E.; Lee, J.; Ainsworth, T.; Schuler, D.; Grandi, G.; Rosen, P.; Peltzer, G.

    1998-01-01

    During the past decade, Radar Polarimetry has established itself as a mature science and advanced technology in high resolution POL-SAR imaging, image target characterization and selective image feature extraction.

  13. Combined optical micromanipulation and interferometric topography (COMMIT)

    PubMed Central

    Sarshar, Mohammad; Lu, Thompson; Anvari, Bahman

    2016-01-01

    Optical tweezers have emerged as a prominent light-based tool for pico-Newton (pN) force microscopy in mechanobiological studies. However, the efficacy of optical tweezers are limited in applications where concurrent metrology of the nano-sized structures under interrogation is essential to the quantitative analysis of its mechanical properties and various mechanotransduction events. We have developed an all-optical platform delivering pN force resolution in parallel with nano-scale structural imaging of the biological sample by combining optical tweezers with interferometric quantitative phase microscopy. These capabilities allow real-time micromanipulation and label-free measurement of sample’s nanostructures and nanomechanical responses, opening avenues to a wide range of new research possibilities and applications in biology. PMID:27446661

  14. Interferometric synthetic aperture radar (InSAR) and its applications to study volcanoes, part 1: Principles of InSAR

    USGS Publications Warehouse

    Lu, Zhong; Zhang, Jixian; Zhang, Yonghong

    2006-01-01

    Interferometric synthetic aperture radar is an ability to measure the surface deformation of remote sensing technology, in a huge area, its deformation measurement with sub-centimeter accuracy, and spatial resolution in the tens of meters or less. In this paper, the basic theory of InSAR technology is reviewed, its working principle is clarified, and the related problems of surface deformation measurement using InSAR technology are discussed.

  15. Interferometric phase-contrast X-ray CT imaging of VX2 rabbit cancer at 35keV X-ray energy

    SciTech Connect

    Takeda, Tohoru; Wu Jin; Tsuchiya, Yoshinori; Lwin, Thet-Thet; Itai, Yuji; Yoneyama, Akio; Hyodo, Kazuyuki

    2004-05-12

    Imaging of large objects at 17.7-keV low x-ray energy causes huge x-ray exposure to the objects even using interferometric phase-contrast x-ray CT (PCCT). Thus, we tried to obtain PCCT images at high x-ray energy of 35keV and examined the image quality using a formalin-fixed VX2 rabbit cancer specimen with 15-mm in diameter. The PCCT system consisted of an asymmetrically cut silicon (220) crystal, a monolithic x-ray interferometer, a phase-shifter, an object cell and an x-ray CCD camera. The PCCT at 35 keV clearly visualized various inner structures of VX2 rabbit cancer such as necrosis, cancer, the surrounding tumor vessels, and normal liver tissue. Besides, image-contrast was not degraded significantly. These results suggest that the PCCT at 35 KeV is sufficient to clearly depict the histopathological morphology of VX2 rabbit cancer specimen.

  16. Interferometric synthetic aperture microscopy

    PubMed Central

    Ralston, Tyler S.; Marks, Daniel L.; Carney, P. Scott; Boppart, Stephen A.

    2014-01-01

    State-of-the-art methods in high-resolution three-dimensional optical microscopy require that the focus be scanned through the entire region of interest. However, an analysis of the physics of the light–sample interaction reveals that the Fourier-space coverage is independent of depth. Here we show that, by solving the inverse scattering problem for interference microscopy, computed reconstruction yields volumes with a resolution in all planes that is equivalent to the resolution achieved only at the focal plane for conventional high-resolution microscopy. In short, the entire illuminated volume has spatially invariant resolution, thus eliminating the compromise between resolution and depth of field. We describe and demonstrate a novel computational image-formation technique called interferometric synthetic aperture microscopy (ISAM). ISAM has the potential to broadly impact real-time three-dimensional microscopy and analysis in the fields of cell and tumour biology, as well as in clinical diagnosis where in vivo imaging is preferable to biopsy. PMID:25635181

  17. Performance of the restoration of interferometric images from the Large Binocular Telescope: the effects of angular coverage and partial adaptive optics correction

    NASA Astrophysics Data System (ADS)

    Carbillet, Marcel; Correia, Serge; Boccacci, Patrizia; Bertero, Mario

    2003-02-01

    This presentation reports the status of our study concerning the imaging properties of the Large Binocular Telescope (LBT) interferometer, and namely the effect of limited angular coverage and partial adaptive optics (AO) correction. The limitation in angular coverage, together with the correlated problem of angular smearing due to time-averaging of the interferometric images, is investigated for relevant cases depending on the declination of the observed object. Results are encouraging even in case of incomplete coverage. Partial AO-correction can result in a wide range of image quality, but can also create significant differences within a same field-of-view, especially between a suitable reference star to be used for post-observation multiple deconvolution and the observed object. Our study deals with both the problem of space-variance of the AO-corrected point-spread function, and that of global quality of the AO-correction. Uniformity, rather than global quality, is found to be the key-problem. After considering the single-conjugate AO case, we reach to some conclusions for the more interesting, and actually wide-field, case implying multi-conjugate AO. The whole study is performed on different types of object, from binary stars to diffuse objects, and a combined one with a high-dynamic range.

  18. Application and Evaluation of ALOS PALSAR Data for Monitoring of Mining Induced Surface Deformations Using Interferometric Techniques

    NASA Astrophysics Data System (ADS)

    Walter, Diana; Wegmuller, Urs; Spreckels, Volker; Busch, Wolfgang

    2008-11-01

    The main objective of the projects "Determination of ground motions in mining areas by interferometric analyses of ALOS data" (ALOS ADEN 3576, ESA) and "Monitoring of mining induced surface deformation" (ALOS-RA-094, JAXA) is to evaluate PALSAR data for surface deformation monitoring, using interferometric techniques. We present monitoring results of surface movements for an active hard coal colliery of the German hard coal mining company RAG Deutsche Steinkohle (RAG). Underground mining activities lead to ground movements at the surface with maximum subsidence rates of about 10cm per month for the test site. In these projects the L-band sensor clearly demonstrates the good potential for deformation monitoring in active mining areas, especially in rural areas. In comparison to C-band sensors we clearly observe advantages in resolving the high deformation gradients that are present in this area and we achieve a more complete spatial coverage than with C-band. Extensive validation data based on levelling data and GPS measurements are available within RAǴs GIS based database "GeoMon" and thus enable an adequate analysis of the quality of the interferometric results. Previous analyses confirm the good accuracy of PALSAR data for deformation monitoring in mining areas. Furthermore, we present results of special investigations like precision geocoding of PALSAR data and corner reflector analysis. At present only DInSAR results are obtained due to the currently available number of PALSAR scenes. For the future we plan to also apply Persistent Scatterer Interferometry (PSI) using longer series of PALSAR data.

  19. Interferometric Plasmonic Lensing with Nanohole Arrays.

    PubMed

    Gong, Yu; Joly, Alan G; El-Khoury, Patrick Z; Hess, Wayne P

    2014-12-18

    Nonlinear photoemission electron microscopy (PEEM) of nanohole arrays in gold films is used to map propagating surface plasmons (PSPs) launched from lithographically patterned structures. Strong near-field photoemission patterns are observed in the PEEM images, recorded following low angle of incidence irradiation of nanohole arrays with sub-15 fs laser pulses centered at 780 nm. The recorded photoemission patterns are attributed to constructive and destructive interference between PSPs launched from the individual nanoholes which comprise the array. By exploiting the wave nature of PSPs, we demonstrate how varying the array geometry (hole diameter, pitch, and number of rows/columns) ultimately yields intense localized photoemission. Through a combination of PEEM experiments and finite-difference time-domain simulations, we identify the optimal array geometry for efficient light coupling and interferometric plasmonic lensing. We show a preliminary application of inteferometric plasmonic lensing by enhancing the photoemission from the vertex of a gold triangle using a nanohole array.

  20. Interferometric Plasmonic Lensing with Nanohole Arrays

    SciTech Connect

    Gong, Yu; Joly, Alan G.; El-Khoury, Patrick Z.; Hess, Wayne P.

    2014-12-18

    Nonlinear photoemission electron microscopy (PEEM) of nanohole arrays in gold films maps propagating surface plasmons (PSPs) launched from lithographically patterned structures. Strong near field photoemission patterns are observed in the PEEM images, recorded following low angle of incidence irradiation of nanohole arrays with sub-15 fs laser pulses centered at 780 nm. The recorded photoemission patterns are attributed to constructive and destructive interferences between PSPs launched from the individual nanoholes which comprise the array. By exploiting the wave nature of PSPs, we demonstrate how varying the array geometry (hole diameter, pitch, and number of rows/columns) ultimately yields intense localized photoemission. Through a combination of PEEM and finite-difference time-domain simulations, we identify the optimal array geometry for efficient light coupling and interferometric plasmonic lensing. We show a preliminary application of inteferometric plasmonic lensing by enhancing the photoemission from the vertex of a gold triangle using nanohole array.

  1. An Automated Mapping Processor using C-Band Interferometric SAR Data

    NASA Technical Reports Server (NTRS)

    Rodriguez, E.; Michel, T. R.; Martin, J. M.; Houshmand, B.

    1996-01-01

    We describe a processor which has been implemented to generate map products starting from C-band interferometric data. The first stage of the processor consists of the conventional interferometric synthetic aperture radar (SAR) processing producing a digital elevation model (DEM) and a SAR brightness image in sensor coordinates. In the second stage of processing, a land use classification map is obtained by using the DEM, brightness, and interferometric correlation layers. Auxiliary layers which include a drainage layer, a height gradient layer, a height error layer, an estimated penetration layer, and a shaded relief layer are also computed. In the final step, all UTM collocated layers are combined in a geographical information system (GIS) which allows for both hard copy map products and digital applications.

  2. An Automated Mapping Processor Using C-Band Interferometric SAR Data

    NASA Technical Reports Server (NTRS)

    Rodriguez, E.; Michel, T. R.; Martin, J. M.; Houshmand, B.

    1996-01-01

    We present the description of a processor which has been implemented to generate map products starting from C-band interferometric data. The first stage of the processor consists of the conventional interferometric SAR processing producing a Digital Elevation Model (DEMs) and a SAR brightness image in sensor coordinates. In the second stage of processing, a land use classification map is obtained by using the DEM, brightness, and interferometric correlation layers. Auxiliary layers which include a drainage layer, a height gradient layer, a height error layer, an estimated penetration layer, and a shaded relief layer are also computed. In the final step, all UTM collocated layers are combined in a GIS system which allows for both hard copy map products and for digital applications.

  3. Near-Infrared Interferometric Images of the Solar System Sized Disk Surrounding the Herbig Ae/Be Star MWC 349A

    NASA Technical Reports Server (NTRS)

    Danchi, W.C.; Tuthill, P. G.; Monnier, J. D.; Fisher, Richard (Technical Monitor)

    2000-01-01

    We present images of the Herbig Ae/Be star MWC 349A at 1.65 and 2.27, and 3.08 micrometers, reconstructed from complex visibility data obtained with an aperture masking interferometric technique on the Keck I telescope. These images have an approximately elliptical shape, and are consistent with the expected shape of a nearly edge-on Keplerian disk. Visibility data were fitted with uniform ellipses with major axes 36 +/- 2, 47 +/- 2, and 62 +/- 1 mas, respectively. The axial ratio of the ellipses is approximately 0.5 +/- 0.1, and the major axis is at a position angle of 100 +/- 3 degrees, consistent with the position angle of the dark lane observed previously in the Very Large Array (VLA) radio continuum maps at 8 and 22 GHz, perpendicular to the symmetry axis of the bipolar lobes of H66(alpha) recombination line emission, and consistent with positions of the recombination line maser spots at 1.3 mm. At an assumed distance of 1.2 kpc, the linear sizes of the disk are 44 and 57 AU at 1.65 and 2.2 micrometers, respectively. The disk is the presumed source of ionized material in the bipolar outflow and ultracompact HII region around the star.

  4. Line-of-Sight Observables Algorithms for the Helioseismic and Magnetic Imager (HMI) Instrument Tested with Interferometric Bidimensional Spectrometer (IBIS) Observations

    NASA Astrophysics Data System (ADS)

    Couvidat, Sébastien; Rajaguru, S. P.; Wachter, Richard; Sankarasubramanian, K.; Schou, Jesper; Scherrer, Philip H.

    2012-05-01

    The Helioseismic and Magnetic Imager (HMI) instrument onboard the Solar Dynamics Observatory produces line-of-sight (LOS) observables (Doppler velocity, magnetic-field strength, Fe i line width, line depth, and continuum intensity) as well as vector magnetic-field maps at the solar surface. The accuracy of LOS observables is dependent on the algorithm used to translate a sequence of HMI filtergrams into the corresponding observables. Using one hour of high-cadence imaging spectropolarimetric observations of a sunspot in the Fe i line at 6173 Å through the Interferometric Bidimensional Spectrometer installed at the Dunn Solar Telescope, and the Milne-Eddington inversion of the corresponding Stokes vectors, we test the accuracy of the observables algorithm currently implemented in the HMI data-analysis pipeline: the MDI-like algorithm. In an attempt to improve the accuracy of HMI observables, we also compare this algorithm to others that may be implemented in the future: a least-squares fit with a Gaussian profile, a least-squares fit with a Voigt profile, and the use of second Fourier coefficients in the MDI-like algorithm.

  5. Imaging and chemical surface analysis of biomolecular functionalization of monolithically integrated on silicon Mach-Zehnder interferometric immunosensors

    NASA Astrophysics Data System (ADS)

    Gajos, Katarzyna; Angelopoulou, Michailia; Petrou, Panagiota; Awsiuk, Kamil; Kakabakos, Sotirios; Haasnoot, Willem; Bernasik, Andrzej; Rysz, Jakub; Marzec, Mateusz M.; Misiakos, Konstantinos; Raptis, Ioannis; Budkowski, Andrzej

    2016-11-01

    Time-of-flight secondary ion mass spectrometry (imaging, micro-analysis) has been employed to evaluate biofunctionalization of the sensing arm areas of Mach-Zehnder interferometers monolithically integrated on silicon chips for the immunochemical (competitive) detection of bovine κ-casein in goat milk. Biosensor surfaces are examined after: modification with (3-aminopropyl)triethoxysilane, application of multiple overlapping spots of κ-casein solutions, blocking with 100-times diluted goat milk, and reaction with monoclonal mouse anti-κ-casein antibodies in blocking solution. The areas spotted with κ-casein solutions of different concentrations are examined and optimum concentration providing homogeneous coverage is determined. Coverage of biosensor surfaces with biomolecules after each of the sequential steps employed in immunodetection is also evaluated with TOF-SIMS, supplemented by Atomic force microscopy and X-ray photoelectron spectroscopy. Uniform molecular distributions are observed on the sensing arm areas after spotting with optimum κ-casein concentration, blocking and immunoreaction. The corresponding biomolecular compositions are determined with a Principal Component Analysis that distinguished between protein amino acids and milk glycerides, as well as between amino acids characteristic for Mabs and κ-casein, respectively. Use of the optimum conditions (κ-casein concentration) for functionalization of chips with arrays of ten Mach-Zehnder interferometers provided on-chips assays with dramatically improved both intra-chip response repeatability and assay detection sensitivity.

  6. The Space Infrared Interferometric Telescope (SPIRIT): High-Resolution Imaging and Spectroscopy in the Far-Infrared (Preprint)

    DTIC Science & Technology

    2007-01-01

    characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets of different...characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets of different types form...composition; (2) characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets of

  7. Superresolved spatially multiplexed interferometric microscopy.

    PubMed

    Picazo-Bueno, José Ángel; Zalevsky, Zeev; García, Javier; Micó, Vicente

    2017-03-01

    Superresolution capability by angular and time multiplexing is implemented onto a regular microscope. The technique, named superresolved spatially multiplexed interferometric microscopy (S2MIM), follows our previously reported SMIM technique [Opt. Express22, 14929 (2014)OPEXFF1094-408710.1364/OE.22.014929, J. Biomed. Opt.21, 106007 (2016)JBOPFO1083-366810.1117/1.JBO.21.10.106007] improved with superresolved imaging. All together, S2MIM updates a commercially available non-holographic microscope into a superresolved holographic one. Validation is presented for an Olympus BX-60 upright microscope with resolution test targets.

  8. Improved Interferometric Photorefractive Optical Processor

    NASA Technical Reports Server (NTRS)

    Cheng, Li-Jen; Liu, Tsuen-Hsi

    1991-01-01

    Processing speed increased substantially. Improved optical interferometric image-processing scheme based on four-wave mixing via photorefractive effect in GaAs or InP. Gives rise to index-of-refraction gratings acting as phase-conjugate mirrors: interactions among four input beams generate wave-front-reversed replicas of two of these beams. Each phase-conjugate beam travels precisely back along path of corresponding input beam, regardless of angle of incidence. Any distortions introduced into input beam during forward propagation removed from phase-conjugate beam during backward propagation.

  9. Applications of Molecular Imaging

    PubMed Central

    Galbán, Craig; Galbán, Stefanie; Van Dort, Marcian; Luker, Gary D.; Bhojani, Mahaveer S.; Rehemtualla, Alnawaz; Ross, Brian D.

    2015-01-01

    Today molecular imaging technologies play a central role in clinical oncology. The use of imaging techniques in early cancer detection, treatment response and new therapy development is steadily growing and has already significantly impacted clinical management of cancer. In this chapter we will overview three different molecular imaging technologies used for the understanding of disease biomarkers, drug development, or monitoring therapeutic outcome. They are (1) optical imaging (bioluminescence and fluorescence imaging) (2) magnetic resonance imaging (MRI), and (3) nuclear imaging (e.g, single photon emission computed tomography (SPECT) and positron emission tomography (PET)). We will review the use of molecular reporters of biological processes (e.g. apoptosis and protein kinase activity) for high throughput drug screening and new cancer therapies, diffusion MRI as a biomarker for early treatment response and PET and SPECT radioligands in oncology. PMID:21075334

  10. Photoacoustic microtomography using optical interferometric detection

    NASA Astrophysics Data System (ADS)

    Nuster, Robert; Holotta, Markus; Kremser, Christian; Grossauer, Harald; Burgholzer, Peter; Paltauf, Günther

    2010-03-01

    A device for three-dimensional (3-D) photoacoustic tomography with resolution in the range of tens of micrometers is presented that uses a light beam for interferometric detection of acoustic waves. Reconstruction of the 3-D initial pressure distribution from the signals representing line integrals of the acoustic field is a two-step process. It uses an inversion of 2-D wave propagation to obtain line projections of the initial pressure distribution and the inverse Radon transform. The light beam, propagating freely in a water bath, is scanned either in an arc- or box-shaped curve around the object. Simulations are performed to compare the two scanning procedures. The projection images are obtained either using the filtered back projection algorithm for the π-arc scanning mode or the frequency domain algorithm for the box scanning mode. While the former algorithm provides slightly better image quality, the latter is about 20 times faster. The ability of the photoacoustic tomography device to create 3-D images with constant resolution throughout the reconstruction volume is demonstrated experimentally using a human hair phantom. These measurements revealed a 3-D resolution below 100 μm. In a second experiment, 3-D imaging of an isolated mouse heart is demonstrated to show the applicability for preclinical and biological research.

  11. Robust high-contrast companion detection from interferometric observations. The CANDID algorithm and an application to six binary Cepheids

    NASA Astrophysics Data System (ADS)

    Gallenne, A.; Mérand, A.; Kervella, P.; Monnier, J. D.; Schaefer, G. H.; Baron, F.; Breitfelder, J.; Le Bouquin, J. B.; Roettenbacher, R. M.; Gieren, W.; Pietrzyński, G.; McAlister, H.; ten Brummelaar, T.; Sturmann, J.; Sturmann, L.; Turner, N.; Ridgway, S.; Kraus, S.

    2015-07-01

    Context. Long-baseline interferometry is an important technique to spatially resolve binary or multiple systems in close orbits. By combining several telescopes together and spectrally dispersing the light, it is possible to detect faint components around bright stars in a few hours of observations. Aims: We provide a rigorous and detailed method to search for high-contrast companions around stars, determine the detection level, and estimate the dynamic range from interferometric observations. Methods: We developed the code CANDID (Companion Analysis and Non-Detection in Interferometric Data), a set of Python tools that allows us to search systematically for point-source, high-contrast companions and estimate the detection limit using all interferometric observables, i.e., the squared visibilities, closure phases and bispectrum amplitudes. The search procedure is made on a N × N grid of fit, whose minimum needed resolution is estimated a posteriori. It includes a tool to estimate the detection level of the companion in the number of sigmas. The code CANDID also incorporates a robust method to set a 3σ detection limit on the flux ratio, which is based on an analytical injection of a fake companion at each point in the grid. Our injection method also allows us to analytically remove a detected component to 1) search for a second companion; and 2) set an unbiased detection limit. Results: We used CANDID to search for the companions around the binary Cepheids V1334 Cyg, AX Cir, RT Aur, AW Per, SU Cas, and T Vul. First, we showed that our previous discoveries of the components orbiting V1334 Cyg and AX Cir were detected at >25σ and >13σ, respectively. The astrometric positions and flux ratios provided by CANDID for these two stars are in good agreement with our previously published values. The companion around AW Per is detected at more than 15σ with a flux ratio of f = 1.22 ± 0.30%, and it is located at ρ = 32.16 ± 0.29 mas and PA = 67.1 ± 0.3°. We made a

  12. Identifying and discriminating phase transitions along decaying shocks with line imaging Doppler interferometric velocimetry and streaked optical pyrometry

    SciTech Connect

    Millot, Marius

    2016-01-15

    Ultrafast line-imaging velocity interferometer system for any reflector and streaked optical pyrometry are now commonly used to obtain high precision equation of state and electronic transport data under dynamic compression at major high energy density science facilities. We describe a simple way to improve distinguishing phase transformation signatures from other signals when monitoring decaying shock waves. The line-imaging capability of these optical diagnostics offers additional supporting evidence to the assignment of particular anomalies—such as plateaus or reversals—to the occurrence of a phase transition along the Hugoniot. We illustrate the discussion with two example datasets collected during laser driven shock compression of quartz and stishovite.

  13. Identifying and discriminating phase transitions along decaying shocks with line imaging Doppler interferometric velocimetry and streaked optical pyrometry

    NASA Astrophysics Data System (ADS)

    Millot, Marius

    2016-01-01

    Ultrafast line-imaging velocity interferometer system for any reflector and streaked optical pyrometry are now commonly used to obtain high precision equation of state and electronic transport data under dynamic compression at major high energy density science facilities. We describe a simple way to improve distinguishing phase transformation signatures from other signals when monitoring decaying shock waves. The line-imaging capability of these optical diagnostics offers additional supporting evidence to the assignment of particular anomalies—such as plateaus or reversals—to the occurrence of a phase transition along the Hugoniot. We illustrate the discussion with two example datasets collected during laser driven shock compression of quartz and stishovite.

  14. Advances in the development of a Mach-Zehnder interferometric Doppler imager for seismology of giant planets

    NASA Astrophysics Data System (ADS)

    Gonçalves, Ivan; Schmider, François-Xavier; Bresson, Yves; Dejonghe, Julien; Preis, Olivier; Robbe-Dubois, Sylvie; Appourchaux, Thierry; Boumier, Patrick; Leclec'h, Jean-Christophe; Morinaud, Gilles; Gaulme, Patrick; Jackiewicz, Jason

    2016-08-01

    The measurements of radial velocity fields on planets with a Doppler Spectro-Imager allow the study of atmospheric dynamics of giant planets and the detection of their acoustic oscillations. The frequencies of these oscillations lead to the determination of the internal structure by asteroseismology. A new imaging tachometer, based on a Mach-Zehnder interferometer, has been developed to monitor the Doppler shift of solar lines reflected at the surface of the planets. We present the principle of this instrument. A prototype was designed and built, following the specifications of a future space mission. The performance of the prototype, both at the laboratory and on the sky, is presented here.

  15. Robust snapshot interferometric spectropolarimetry.

    PubMed

    Kim, Daesuk; Seo, Yoonho; Yoon, Yonghee; Dembele, Vamara; Yoon, Jae Woong; Lee, Kyu Jin; Magnusson, Robert

    2016-05-15

    This Letter describes a Stokes vector measurement method based on a snapshot interferometric common-path spectropolarimeter. The proposed scheme, which employs an interferometric polarization-modulation module, can extract the spectral polarimetric parameters Ψ(k) and Δ(k) of a transmissive anisotropic object by which an accurate Stokes vector can be calculated in the spectral domain. It is inherently strongly robust to the object 3D pose variation, since it is designed distinctly so that the measured object can be placed outside of the interferometric module. Experiments are conducted to verify the feasibility of the proposed system. The proposed snapshot scheme enables us to extract the spectral Stokes vector of a transmissive anisotropic object within tens of msec with high accuracy.

  16. Application-driven computational imaging

    NASA Astrophysics Data System (ADS)

    McCloskey, Scott

    2016-05-01

    This paper addresses how the image processing steps involved in computational imaging can be adapted to specific image-based recognition tasks, and how significant reductions in computational complexity can be achieved by leveraging the recognition algorithm's robustness to defocus, poor exposure, and the like. Unlike aesthetic applications of computational imaging, recognition systems need not produce the best possible image quality, but instead need only satisfy certain quality thresholds that allow for reliable recognition. The paper specifically addresses light field processing for barcode scanning, and presents three optimizations which bring light field processing within the complexity limits of low-powered embedded processors.

  17. Polarization-sensitive interferometric synthetic aperture microscopy

    PubMed Central

    South, Fredrick A.; Liu, Yuan-Zhi; Xu, Yang; Shemonski, Nathan D.; Carney, P. Scott; Boppart, Stephen A.

    2015-01-01

    Three-dimensional optical microscopy suffers from the well-known compromise between transverse resolution and depth-of-field. This is true for both structural imaging methods and their functional extensions. Interferometric synthetic aperture microscopy (ISAM) is a solution to the 3D coherent microscopy inverse problem that provides depth-independent transverse resolution. We demonstrate the extension of ISAM to polarization sensitive imaging, termed polarization-sensitive interferometric synthetic aperture microscopy (PS-ISAM). This technique is the first functionalization of the ISAM method and provides improved depth-of-field for polarization-sensitive imaging. The basic assumptions of polarization-sensitive imaging are explored, and refocusing of birefringent structures is experimentally demonstrated. PS-ISAM enables high-resolution volumetric imaging of birefringent materials and tissue. PMID:26648593

  18. Delay-Doppler and Radar-Interferometric Imaging of the Near-Earth Asteroid 2008 EV5

    NASA Astrophysics Data System (ADS)

    Busch, Michael W.; Kulkarni, S. R.; Ostro, S. J.; Brisken, W.; Benner, L. A. M.; Nolan, M. C.; Giorgini, J. D.; Brozovic, M.; Magri, C.

    2009-09-01

    Very-Long-Baseline Interferometry (VLBI) provides the highest angular resolution of any astronomical imaging technique. VLBI-radar plane-of-sky imaging of near-Earth asteroids can provide astrometry, relative orbits of binaries, unambiguous shapes, and maps of surface properties well beyond conventional delay-Doppler imaging, for a subset of Arecibo radar targets. 2008 EV5 was discovered by the Mt. Lemmon Survey on Mar 4 2008, and approached to within 8.4 lunar distances on 2008 Dec 23. We observed it with delay-Doppler imaging at Goldstone during 2008 Dec 16-23 and at Arecibo during Dec 23-27. On Dec 23 & 24, we also observed with Arecibo CW transmissions and the VLBA and Green Bank receiving. The delay-Doppler data provide 7.5-m spatial resolution, showing that EV5 is a roughly 450 m spheroid, with a slight equatorial ridge and a prominent concavity (150-200 m across). However, the delay-Doppler data alone provide two mirror solutions for the asteroid's pole direction. The two pole directions predict opposite Yarkovsky accelerations, producing a several million kilometer offset in the asteroid's trajectory by 2170. The VLBA+GBT plane-of-sky images have 100 m resolution. We are currently combining the delay-Doppler and VLBI data and will report our results. This material is based partially on work supported by NASA's Science Mission Directorate Research and Analysis Programs. The VLBA is operated by Associated Universities for the NSF. Arecibo Observatory is run by Cornell for the NSF. M.W.B. was supported by the Hertz Foundation.

  19. Interferometric modulator with phase-modulating and cavity-modulating components (IMPACC) for high linearity microwave applications: technology review

    NASA Astrophysics Data System (ADS)

    Madamopoulos, N.; Dingel, B.; Prescod, A.

    2013-06-01

    In this invited paper, we review the theoretical model and performance of an Interferometric Modulator with Phase modulating And Cavity-modulating Components (IMPACC). IMPACC has the highest reported SFDR (e.g., 132 dB-Hz) and offers additional advantages compared to other Mach-Zehnder Interferometer (MZI) based electro-optic modulators (e.g., MZI, ring-assisted MZI or RAMZI). The modulator is based on a unique combination of a RF driven phase-modulator (PM) and a ring resonator (RR) within a MZI interferometer. Both the PM and RR in the IMPACC are simultaneously driven by a RF signal of the same frequency, but not necessarily the same amplitude and phase. Here, we summarize the non-ideal and oftentimes detrimental effects such as: (1) RF bandwidth limitation due to free spectral range (FSR) of the RR, (2) RR waveguide loss, (3) deviation of RR coupling ratio from the ideal value, and (4) unbalanced MZ splitter/coupler on the performance of both IMPACC and RAMZI. We show that proper choice of RF power split ratio and RF phase for IMPACC compensate these negative effects and recover IMPACC's ideal performance. Unlike RAMZI, this translates to higher device tolerance, added manufacturing flexibility, and superior modulator performance.

  20. Efficient correction for both direction-dependent and baseline-dependent effects in interferometric imaging: An A-stacking framework

    NASA Astrophysics Data System (ADS)

    Young, A.; Wijnholds, S. J.; Carozzi, T. D.; Maaskant, R.; Ivashina, M. V.; Davidson, D. B.

    2015-05-01

    A general framework is presented for modeling direction-dependent effects that are also baseline-dependent, as part of the calibration and imaging process. Within this framework such effects are represented as a parametric linear model in which basis functions account for direction dependence, whereas expansion coefficients account for the baseline dependence. This separation enables the use of a multiple fast Fourier transform-based implementation of the forward calculation (sky to visibility) in a manner similar to the W-stacking solution for non-coplanar baselines, and offers a potential improvement in computational efficiency in scenarios where the gridding operation in a convolution-based approach to direction-dependent effects may be too costly. Two novel imaging approaches that are possible within this framework are also presented.

  1. Spectral imaging: principles and applications.

    PubMed

    Garini, Yuval; Young, Ian T; McNamara, George

    2006-08-01

    Spectral imaging extends the capabilities of biological and clinical studies to simultaneously study multiple features such as organelles and proteins qualitatively and quantitatively. Spectral imaging combines two well-known scientific methodologies, namely spectroscopy and imaging, to provide a new advantageous tool. The need to measure the spectrum at each point of the image requires combining dispersive optics with the more common imaging equipment, and introduces constrains as well. The principles of spectral imaging and a few representative applications are described. Spectral imaging analysis is necessary because the complex data structure cannot be analyzed visually. A few of the algorithms are discussed with emphasis on the usage for different experimental modes (fluorescence and bright field). Finally, spectral imaging, like any method, should be evaluated in light of its advantages to specific applications, a selection of which is described. Spectral imaging is a relatively new technique and its full potential is yet to be exploited. Nevertheless, several applications have already shown its potential. (c) 2006 International Society for Analytical Cytology.

  2. The Fringe-Imaging Skin Friction Technique PC Application User's Manual

    NASA Technical Reports Server (NTRS)

    Zilliac, Gregory G.

    1999-01-01

    A personal computer application (CXWIN4G) has been written which greatly simplifies the task of extracting skin friction measurements from interferograms of oil flows on the surface of wind tunnel models. Images are first calibrated, using a novel approach to one-camera photogrammetry, to obtain accurate spatial information on surfaces with curvature. As part of the image calibration process, an auxiliary file containing the wind tunnel model geometry is used in conjunction with a two-dimensional direct linear transformation to relate the image plane to the physical (model) coordinates. The application then applies a nonlinear regression model to accurately determine the fringe spacing from interferometric intensity records as required by the Fringe Imaging Skin Friction (FISF) technique. The skin friction is found through application of a simple expression that makes use of lubrication theory to relate fringe spacing to skin friction.

  3. Coherence versus interferometric resolution

    SciTech Connect

    Luis, Alfredo

    2010-06-15

    We examine the relation between second-order coherence and resolution in the interferometric detection of phase shifts. While for classical thermal light resolution and second-order coherence are synonymous, we show that for quantum light beams reaching optimum precision second-order coherence and resolution become antithetical.

  4. Interferometric investigations with the S1 constellation: an application to the Vesuvius/Campi Flegrei volcanic test site

    NASA Astrophysics Data System (ADS)

    Borgstrom, Sven; Del Gaudio, Carlo; De Martino, Prospero; Siniscalchi, Valeria; Prats-Iraola, Pau; Nannini, Matteo; Yague-Martinez, Nestor; Pinheiro, Muriel; Kim, Jun-Su; Vecchioli, Francesco; Minati, Federico; Costantini, Mario; Foumelis, Michael; Desnos, Yves-Louis

    2017-04-01

    The contribution focuses on the current status of the ESA study entitled "INSARAP Sentinel-1 Constellation Study" and investigates the interferometric performance of the S1A/S1B units. In particular, we refer to the Vesuvius/Campi Flegrei (Southern Italy) volcanic test site, where the continuous inflation (about 35 cm from 2011 to date) and the huge availability of ground-based geodetic data (continuous GPS - cGPS - leveling, tiltmetric, gravimetric, etc.) from the INGV-Osservatorio Vesuviano monitoring networks have allowed to get a clear deformation signal, besides the comparison between S1A/S1B and geodetic data. In this regard, the integration between InSAR and geodetic measurements is crucial for a continuous and extended monitoring of such an active volcanic area, as InSAR investigations allow to get an information on wide areas, whereas permanent networks (e.g., cGPS), allow to provide a continuous information complementing InSAR, which is limited by its revisiting time. Comparisons between S1 constellation data and geodetic measurements, with a particular focus on cGPS, will be presented, exploiting both LOS and inverted (E-W and vertical inversion) InSAR data starting from October, 2014. In addition, as a next step we are planning to model the deformation source of the area by exploiting the S1 time series results. Ultimately, very encouraging results suggest for a continuation of this activity also for the future, showing the great potential of S1 constellation data for monitoring active volcanic areas and, in general, to retrieve a very high quality deformation signal.

  5. Application of the Seismic Interferometric Method to Image Lithospheric Structure of the Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Kim, Ki Young; Park, Iseul; Byun, Joongmoo

    2017-04-01

    To delineate the lithospheric structure of the southern part of the Korean peninsula, the seismic interferometry method was applied to the crustal refraction data recorded in 2002. The seismic signals were generated by detonating 1000 and 500 kg explosives in drill holes on a 294-km WNW-ESE profile, and recorded by 2-Hz portable seismometers at a nominal interval of 1.5 km. Seismic interferometry was applied to extract the reflected-wave Green's functions from the coarsely-spaced crustal data. Cross-correlation of each pair of seismic traces yielded 195 virtual shot gathers for each real shot. Autocorrelation functions of source signatures were then removed by zero-phase deconvolution of the virtual data. Finally, conventional seismic reflection processing techniques of gain recovery, band-pass filtering, normal moveout correction, muting, common-midpoint stacking, predictive deconvolution, and migration were applied. The preliminary reflection section indicates very complex geologic structures, including many inclined shear zones.

  6. Real-time interferometric synthetic aperture microscopy

    PubMed Central

    Ralston, Tyler S.; Marks, Daniel L.; Carney, P. Scott; Boppart, Stephen A.

    2010-01-01

    An interferometric synthetic aperture microscopy (ISAM) system design with real-time 2D cross-sectional processing is described in detail. The system can acquire, process, and display the ISAM reconstructed images at frame rates of 2.25 frames per second for 512 × 1024 pixel images. This system provides quantitatively meaningful structural information from previously indistinguishable scattering intensities and provides proof of feasibility for future real-time ISAM systems. PMID:18542337

  7. Pediatric electrocardiographic imaging applications.

    PubMed

    Silva, Jennifer N A

    2015-03-01

    Noninvasive electrocardiographic imaging (ECGI) has been used in pediatric and congenital heart patients to better understand their electrophysiologic substrates. In this article we focus on the 4 subjects related to pediatric ECGI: (1) ECGI in patients with congenital heart disease and Wolff–Parkinson–White syndrome, (2) ECGI in patients with hypertrophic cardiomyopathy and preexcitation, (3) ECGI in pediatric patients with Wolff–Parkinson–White syndrome, and (4) ECGI for pediatric cardiac resynchronization therapy.

  8. Interferometric biochemical and chemical sensors

    NASA Astrophysics Data System (ADS)

    Gauglitz, Guenter; Brecht, Andreas; Kraus, Gerolf

    1995-09-01

    Interferometric principles have gained wide acceptance in the field of chemical and biochemical sensing. Reflectometric interference spectrometry sensors using white light multiple reflections at thin layers, structures of polymers, or monolayers of biochemicals are discussed in a survey. These are compared to other techniques, especially methods using surface plasmon resonance and grating couplers. Applications in the area of environmental monitoring in public safety are given, demonstrating the results for halogenated hydrocarbons in air and water as well as pesticides in ground water. Calibration curves, limits of decision, of detection, and of determination are specified and discussed with respect to EU limits. The application of multivariate data analysis is considered including artificial neuronal networks for multisensor systems and referencing in the case of gas sensors.

  9. Industrial Applications of Image Processing

    NASA Astrophysics Data System (ADS)

    Ciora, Radu Adrian; Simion, Carmen Mihaela

    2014-11-01

    The recent advances in sensors quality and processing power provide us with excellent tools for designing more complex image processing and pattern recognition tasks. In this paper we review the existing applications of image processing and pattern recognition in industrial engineering. First we define the role of vision in an industrial. Then a dissemination of some image processing techniques, feature extraction, object recognition and industrial robotic guidance is presented. Moreover, examples of implementations of such techniques in industry are presented. Such implementations include automated visual inspection, process control, part identification, robots control. Finally, we present some conclusions regarding the investigated topics and directions for future investigation

  10. Industrial Applications of Terahertz Imaging

    NASA Astrophysics Data System (ADS)

    Zeitler, J. Axel; Shen, Yao-Chun

    This chapter gives a concise overview of potential industrial applications for terahertz imaging that have been reported over the past decade with a discussion of the major advantages and limitations of each approach. In the second half of the chapter we discuss in more detail how terahertz imaging can be used to investigate the microstructure of pharmaceutical dosage forms. A particular focus in this context is the nondestructive measurement of the coating thickness of polymer coated tablets, both by means of high resolution offline imaging in research and development as well as for in-line quality control during production.

  11. Precision Interferometric Dilatometer

    DTIC Science & Technology

    2013-05-23

    reference mirrors on a ULE glass or Zerodur block in a thermally insulated - part of the system. Since the BIP, (or B2P2) paths are in air, mounting...into the vacuum chamber. The reference mirror support (e.g., Zerodur ) is shielded from temperature excursion, and a conservative error is ALu - aL... Mirror (1000 V B 15 pm motion)s............s.. 24 10. Interferometric Counter Output vs. Voltage Applied to PZT-Driven Mirror (fine scale

  12. Detection of Fast Transients with Radio Interferometric Arrays

    NASA Astrophysics Data System (ADS)

    Bhat, N. D. R.; Chengalur, J. N.; Cox, P. J.; Gupta, Y.; Prasad, J.; Roy, J.; Bailes, M.; Burke-Spolaor, S.; Kudale, S. S.; van Straten, W.

    2013-05-01

    Next-generation radio arrays, including the Square Kilometre Array (SKA) and its pathfinders, will open up new avenues for exciting transient science at radio wavelengths. Their innovative designs, comprising a large number of small elements, pose several challenges in digital processing and optimal observing strategies. The Giant Metre-wave Radio Telescope (GMRT) presents an excellent test-bed for developing and validating suitable observing modes and strategies for transient experiments with future arrays. Here we describe the first phase of the ongoing development of a transient detection system for GMRT that is planned to eventually function in a commensal mode with other observing programs. It capitalizes on the GMRT's interferometric and sub-array capabilities, and the versatility of a new software backend. We outline considerations in the plan and design of transient exploration programs with interferometric arrays, and describe a pilot survey that was undertaken to aid in the development of algorithms and associated analysis software. This survey was conducted at 325 and 610 MHz, and covered 360 deg2 of the sky with short dwell times. It provides large volumes of real data that can be used to test the efficacies of various algorithms and observing strategies applicable for transient detection. We present examples that illustrate the methodologies of detecting short-duration transients, including the use of sub-arrays for higher resilience to spurious events of terrestrial origin, localization of candidate events via imaging, and the use of a phased array for improved signal detection and confirmation. In addition to demonstrating applications of interferometric arrays for fast transient exploration, our efforts mark important steps in the roadmap toward SKA-era science.

  13. DETECTION OF FAST TRANSIENTS WITH RADIO INTERFEROMETRIC ARRAYS

    SciTech Connect

    Bhat, N. D. R.; Chengalur, J. N.; Gupta, Y.; Prasad, J.; Roy, J.; Kudale, S. S.; Cox, P. J.; Bailes, M.; Burke-Spolaor, S.; Van Straten, W.

    2013-05-01

    Next-generation radio arrays, including the Square Kilometre Array (SKA) and its pathfinders, will open up new avenues for exciting transient science at radio wavelengths. Their innovative designs, comprising a large number of small elements, pose several challenges in digital processing and optimal observing strategies. The Giant Metre-wave Radio Telescope (GMRT) presents an excellent test-bed for developing and validating suitable observing modes and strategies for transient experiments with future arrays. Here we describe the first phase of the ongoing development of a transient detection system for GMRT that is planned to eventually function in a commensal mode with other observing programs. It capitalizes on the GMRT's interferometric and sub-array capabilities, and the versatility of a new software backend. We outline considerations in the plan and design of transient exploration programs with interferometric arrays, and describe a pilot survey that was undertaken to aid in the development of algorithms and associated analysis software. This survey was conducted at 325 and 610 MHz, and covered 360 deg{sup 2} of the sky with short dwell times. It provides large volumes of real data that can be used to test the efficacies of various algorithms and observing strategies applicable for transient detection. We present examples that illustrate the methodologies of detecting short-duration transients, including the use of sub-arrays for higher resilience to spurious events of terrestrial origin, localization of candidate events via imaging, and the use of a phased array for improved signal detection and confirmation. In addition to demonstrating applications of interferometric arrays for fast transient exploration, our efforts mark important steps in the roadmap toward SKA-era science.

  14. Siderophores for molecular imaging applications.

    PubMed

    Petrik, Milos; Zhai, Chuangyan; Haas, Hubertus; Decristoforo, Clemens

    2017-01-01

    This review covers publications on siderophores applied for molecular imaging applications, mainly for radionuclide-based imaging. Siderophores are low molecular weight chelators produced by bacteria and fungi to scavenge essential iron. Research on these molecules has a continuing history over the past 50 years. Many biomedical applications have been developed, most prominently the use of the siderophore desferrioxamine (DFO) to tackle iron overload related diseases. Recent research described the upregulation of siderophore production and transport systems during infection. Replacing iron in siderophores by radionuclides, the most prominent Ga-68 for PET, opens approaches for targeted imaging of infection; the proof of principle has been reported for fungal infections using (68)Ga-triacetylfusarinine C (TAFC). Additionally, fluorescent siderophores and therapeutic conjugates have been described and may be translated to optical imaging and theranostic applications. Siderophores have also been applied as bifunctional chelators, initially DFO as chelator for Ga-67 and more recently for Zr-89 where it has become the standard chelator in Immuno-PET. Improved DFO constructs and bifunctional chelators based on cyclic siderophores have recently been developed for Ga-68 and Zr-89 and show promising properties for radiopharmaceutical development in PET. A huge potential from basic biomedical research on siderophores still awaits to be utilized for clinical and translational imaging.

  15. Fast interferometric second harmonic generation microscopy

    PubMed Central

    Bancelin, Stéphane; Couture, Charles-André; Légaré, Katherine; Pinsard, Maxime; Rivard, Maxime; Brown, Cameron; Légaré, François

    2016-01-01

    We report the implementation of fast Interferometric Second Harmonic Generation (I-SHG) microscopy to study the polarity of non-centrosymmetric structures in biological tissues. Using a sample quartz plate, we calibrate the spatially varying phase shift introduced by the laser scanning system. Compensating this phase shift allows us to retrieve the correct phase distribution in periodically poled lithium niobate, used as a model sample. Finally, we used fast interferometric second harmonic generation microscopy to acquire phase images in tendon. Our results show that the method exposed here, using a laser scanning system, allows to recover the polarity of collagen fibrils, similarly to standard I-SHG (using a sample scanning system), but with an imaging time about 40 times shorter. PMID:26977349

  16. Derivation of terrain slope from SAR interferometric phase gradient

    NASA Technical Reports Server (NTRS)

    Wegmueller, Urs; Werner, Charles L.; Rosen, Paul A.

    1994-01-01

    The relationship between the gradient of the interferometric phase and the terrain slope, which, it is thought, would allow a derivation of the terrain slopes without phase unwrapping, is presented. A linear relationship between the interferometric phase gradient and the terrain slopes was found. A quantitative error analysis showed that only very small errors are introduced by these approximations for orbital Synthetic Aperture Radar (SAR) geometries. An example of a slope map for repeat pass interferometry from ERS-1 SAR data is given. A number of direct and indirect applications of the terrain slope are indicated: erosion and avalanche hazard studies, radiometric calibration of SAR data, and normalization of the interferometric correlation coefficient.

  17. Multifocal interferometric synthetic aperture microscopy

    PubMed Central

    Xu, Yang; Chng, Xiong Kai Benjamin; Adie, Steven G.; Boppart, Stephen A.; Scott Carney, P.

    2014-01-01

    There is an inherent trade-off between transverse resolution and depth of field (DOF) in optical coherence tomography (OCT) which becomes a limiting factor for certain applications. Multifocal OCT and interferometric synthetic aperture microscopy (ISAM) each provide a distinct solution to the trade-off through modification to the experiment or via post-processing, respectively. In this paper, we have solved the inverse problem of multifocal OCT and present a general algorithm for combining multiple ISAM datasets. Multifocal ISAM (MISAM) uses a regularized combination of the resampled datasets to bring advantages of both multifocal OCT and ISAM to achieve optimal transverse resolution, extended effective DOF and improved signal-to-noise ratio. We present theory, simulation and experimental results. PMID:24977909

  18. Image wavelet decomposition and applications

    NASA Technical Reports Server (NTRS)

    Treil, N.; Mallat, S.; Bajcsy, R.

    1989-01-01

    The general problem of computer vision has been investigated for more that 20 years and is still one of the most challenging fields in artificial intelligence. Indeed, taking a look at the human visual system can give us an idea of the complexity of any solution to the problem of visual recognition. This general task can be decomposed into a whole hierarchy of problems ranging from pixel processing to high level segmentation and complex objects recognition. Contrasting an image at different representations provides useful information such as edges. An example of low level signal and image processing using the theory of wavelets is introduced which provides the basis for multiresolution representation. Like the human brain, we use a multiorientation process which detects features independently in different orientation sectors. So, images of the same orientation but of different resolutions are contrasted to gather information about an image. An interesting image representation using energy zero crossings is developed. This representation is shown to be experimentally complete and leads to some higher level applications such as edge and corner finding, which in turn provides two basic steps to image segmentation. The possibilities of feedback between different levels of processing are also discussed.

  19. Computational adaptive optics for broadband optical interferometric tomography of biological tissue

    NASA Astrophysics Data System (ADS)

    Boppart, Stephen A.

    2015-03-01

    High-resolution real-time tomography of biological tissues is important for many areas of biological investigations and medical applications. Cellular level optical tomography, however, has been challenging because of the compromise between transverse imaging resolution and depth-of-field, the system and sample aberrations that may be present, and the low imaging sensitivity deep in scattering tissues. The use of computed optical imaging techniques has the potential to address several of these long-standing limitations and challenges. Two related techniques are interferometric synthetic aperture microscopy (ISAM) and computational adaptive optics (CAO). Through three-dimensional Fourierdomain resampling, in combination with high-speed OCT, ISAM can be used to achieve high-resolution in vivo tomography with enhanced depth sensitivity over a depth-of-field extended by more than an order-of-magnitude, in realtime. Subsequently, aberration correction with CAO can be performed in a tomogram, rather than to the optical beam of a broadband optical interferometry system. Based on principles of Fourier optics, aberration correction with CAO is performed on a virtual pupil using Zernike polynomials, offering the potential to augment or even replace the more complicated and expensive adaptive optics hardware with algorithms implemented on a standard desktop computer. Interferometric tomographic reconstructions are characterized with tissue phantoms containing sub-resolution scattering particles, and in both ex vivo and in vivo biological tissue. This review will collectively establish the foundation for high-speed volumetric cellular-level optical interferometric tomography in living tissues.

  20. Image reconstruction in optical interferometry: application to the inner regions of protoplanetary disks.

    NASA Astrophysics Data System (ADS)

    Renard, Stephanie

    2010-11-01

    Planets are believed to form in disks of gas and dust detected around newly born stars. The study of such circumstellar disks is necessary to understand how the planets form and the origin of our solar system. At the distance of the closest star forming regions, the observation of the disk at distances ranging from 0.1 to 10 AUs corresponds to milli-arcsecond spatial scales. Infrared interferometry is a suitable tool to achieve such spatial scales and to conduct observations of the close environment of such disks. However, an interferometer does not provide a direct image of the observed object. The data obtained so far consist of a small number of measurements which can only constrain theoretical models. With the advent of recent multi-aperture interferometers, the interferometric data can be used to reconstruct images independently of any parametric model, as is routinely done in the radio frequency range. The goal of the present work is to apply the image reconstruction technique to near-infrared interferometric data of young stellar objects. Firstly, a systematic study of the image reconstruction method is done on the MiRA algorithm and practical rules for the users are derived from the tests. Moreover, the study demonstrates that the (u; v) coverage is more critical than the signal-to-noise ratio in the image reconstruction context. Secondly, the method is applied on an Herbig Ae star, MWC275, leading to the first image of a complex young stellar object. Due to the sparseness of the (u; v) coverage, an unambiguous image easy to interpret cannot be derived, even if optimal parameters are used. A methodology, using a model of the observed object, is necessary to not over-interpret the structures in the reconstructed image. Finally, the technique is applied to other young stellar objects. The new applications affirm the interest of the image reconstruction method to analyze the data, but confirm also that the images have to be interpreted carefully.

  1. Clinical applications in molecular imaging.

    PubMed

    Heneweer, Carola; Grimm, Jan

    2011-02-01

    Molecular imaging is aimed at the noninvasive in vivo characterization and measurement of processes at a cellular and molecular level with clinical imaging methods. Contrast agents are constructed to target markers that are specific either for certain diseases or for functional states of specialized tissues. Efforts are currently focused mainly on processes involved in angiogenesis, inflammation, and apoptosis. Cell tracking is performed for diagnostic purposes as well as for monitoring of novel cell therapies. Visualization of these processes would provide more precise information about disease expansion as well as treatment response, and could lead to a more individualized therapy for patients. Many attempts have shown promising results in preclinical studies; however, translation into the clinic remains a challenge. This applies especially to paediatrics because of more stringent safety concerns and the low prevalence of individual diseases. The most promising modalities for clinical translation are nuclear medicine methods (positron emission tomography [PET] and single photon emission CT [SPECT]) due to their high sensitivity, which allows concentrations below biological activity. However, special dose consideration is required for any application of ionizing radiation especially in children. While very little has been published on molecular imaging in a paediatric patient population beyond fluorodeoxyglucose (FDG)-PET and metaiodobenzylguanidine (MIBG) tracers, this review will attempt to discuss approaches that we believe have promise for paediatric imaging. These will include agents that already reached clinical trials as well as preclinical developments with high potential for clinical application.

  2. Application of Diffraction Enhanced Imaging to Medical Imaging

    DTIC Science & Technology

    2001-06-01

    to mammography and other areas of medical imaging . Prof. Chapman is a co-developer of the technique and intends to determine the applicability of... medical imaging . This award has allowed Prof. Chapman to: 1) explore the potential application of Diffraction Enhanced Imaging to mammography, 2...cancer research, and medical imaging , 4) explore the possibility of developing a dedicated imaging program at the Advanced Photon Source, with the

  3. Multipulse interferometric frequency-resolved optical gating

    SciTech Connect

    Siders, C.W.; Siders, J.L.W.; Omenetto, F.G.; Taylor, A.J.

    1999-04-01

    The authors review multipulse interferometric frequency-resolved optical gating (MI-FROG) as a technique, uniquely suited for pump-probe coherent spectroscopy using amplified visible and near-infrared short-pulse systems and/or emissive targets, for time-resolving ultrafast phase shifts and intensity changes. Application of polarization-gate MI-FROG to the study of ultrafast ionization in gases is presented.

  4. (Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. II. The spatial extent of the radio-emitting regions

    NASA Astrophysics Data System (ADS)

    Miettinen, O.; Novak, M.; Smolčić, V.; Schinnerer, E.; Sargent, M.; Murphy, E. J.; Aravena, M.; Bondi, M.; Carilli, C. L.; Karim, A.; Salvato, M.; Zamorani, G.

    2015-12-01

    Radio emission at centimetre wavelengths from highly star-forming galaxies, like submillimetre galaxies (SMGs), is dominated by synchrotron radiation arising from supernova activity. Hence, radio continuum imaging has the potential to determine the spatial extent of star formation in these types of galaxies. Using deep, high-resolution (1σ = 2.3 μJy beam-1; 0.75 arcsec) centimetre radio-continuum observations taken by the Karl G. Jansky Very Large Array (VLA)-COSMOS 3 GHz Large Project, we studied the radio-emitting sizes of a flux-limited sample of SMGs in the COSMOS field. The target SMGs were originally discovered in a 1.1 mm continuum survey carried out with the AzTEC bolometer, and followed up with higher resolution interferometric (sub)millimetre continuum observations. Of the 39 SMGs studied here, 3 GHz emission was detected towards 18 of them (~46 ± 11%) with signal-to-noise ratios in the range of S/N = 4.2-37.4. Towards four SMGs (AzTEC2, 5, 8, and 11), we detected two separate 3 GHz sources with projected separations of ~1''&dotbelow;5-6''&dotbelow;6, but they might be physically related in only one or two cases (AzTEC2 and 11). Using two-dimensional elliptical Gaussian fits, we derived a median deconvolved major axis FWHM size of 0''&dotbelow;54±0''&dotbelow;11 for our 18 SMGs detected at 3 GHz. For the 15 SMGs with known redshift we derived a median linear major axis FWHM of 4.2 ± 0.9 kpc. No clear correlation was found between the radio-emitting size and the 3 GHz or submm flux density, or the redshift of the SMG. However, there is a hint of larger radio sizes at z ~ 2.5-5 compared to lower redshifts. The sizes we derived are consistent with previous SMG sizes measured at 1.4 GHz and in mid-J CO emission, but significantly larger than those seen in the (sub)mm continuum emission (typically probing the rest-frame far-infrared with median FWHM sizes of only ~1.5-2.5 kpc). One possible scenario is that SMGs have i) an extended gas component with a

  5. Quantitative interferometric microscopic flow cytometer with expanded principal component analysis method

    NASA Astrophysics Data System (ADS)

    Wang, Shouyu; Jin, Ying; Yan, Keding; Xue, Liang; Liu, Fei; Li, Zhenhua

    2014-11-01

    Quantitative interferometric microscopy is used in biological and medical fields and a wealth of applications are proposed in order to detect different kinds of biological samples. Here, we develop a phase detecting cytometer based on quantitative interferometric microscopy with expanded principal component analysis phase retrieval method to obtain phase distributions of red blood cells with a spatial resolution ~1.5 μm. Since expanded principal component analysis method is a time-domain phase retrieval algorithm, it could avoid disadvantages of traditional frequency-domain algorithms. Additionally, the phase retrieval method realizes high-speed phase imaging from multiple microscopic interferograms captured by CCD camera when the biological cells are scanned in the field of view. We believe this method can be a powerful tool to quantitatively measure the phase distributions of different biological samples in biological and medical fields.

  6. TE/TM Simulations of Interferometric Measurements

    NASA Technical Reports Server (NTRS)

    Houshmand, Bijan

    2000-01-01

    Interferometric synthetic aperture radar (IFSAR) measurements at X-, C-, L-, and P-band are used to derive ground topography at meter level resolution. Interpretation of the derived topography requires attention due to the complex interaction of the radar signal with ground cover. The presence of penetrable surfaces such as vegetation, and tree canopies poses a challenge since the depth of penetration depends on a number of parameters such as the operating radar frequency, polarization, incident angle, as well as terrain structure. The dependence of the reconstructed topography on polarization may lead to the characterization of the ground cover. Simulation of interferometric measurements is useful for interpretation of the derived topography (B. Houshmand, Proceedings of URSI, 314, 1997). In this talk , time domain simulations for interferometric measurement for TE- and TM- polarization are presented. Time domain simulation includes the effects of the surface material property as well geometry comparable the radar signal wavelength (B. Houshmand, Proceedings of the URSI, 25, 1998). The IFSAR simulation is carried out in two steps. First, the forward scattering data is generated based on full wave analysis. Next, the electromagnetic information is inverted to generate surface topography. This inversion is based on the well known IFSAR processing technique which is composed of signal compression, and formation of an interferogram. The full wave forward scattering data is generated by the scattered-field formulation of the FDTD algorithm. The simulation is carried out by exciting the computational domain by a radar signal. The scattered field is then computed and translated to the receiving interferometric antennas using the time-domain Huygen's principle. The inversion process starts by compressing the time-domain data. The range compressed data from both receivers are then coregistered to form an interferogram. The resulting interferogram is then related to the

  7. Satellite SAR interferometric techniques applied to emergency mapping

    NASA Astrophysics Data System (ADS)

    Stefanova Vassileva, Magdalena; Riccardi, Paolo; Lecci, Daniele; Giulio Tonolo, Fabio; Boccardo Boccardo, Piero; Chiesa, Giuliana; Angeluccetti, Irene

    2017-04-01

    This paper aim to investigate the capabilities of the currently available SAR interferometric algorithms in the field of emergency mapping. Several tests have been performed exploiting the Copernicus Sentinel-1 data using the COTS software ENVI/SARscape 5.3. Emergency Mapping can be defined as "creation of maps, geo-information products and spatial analyses dedicated to providing situational awareness emergency management and immediate crisis information for response by means of extraction of reference (pre-event) and crisis (post-event) geographic information/data from satellite or aerial imagery". The conventional differential SAR interferometric technique (DInSAR) and the two currently available multi-temporal SAR interferometric approaches, i.e. Permanent Scatterer Interferometry (PSI) and Small BAseline Subset (SBAS), have been applied to provide crisis information useful for the emergency management activities. Depending on the considered Emergency Management phase, it may be distinguished between rapid mapping, i.e. fast provision of geospatial data regarding the area affected for the immediate emergency response, and monitoring mapping, i.e. detection of phenomena for risk prevention and mitigation activities. In order to evaluate the potential and limitations of the aforementioned SAR interferometric approaches for the specific rapid and monitoring mapping application, five main factors have been taken into account: crisis information extracted, input data required, processing time and expected accuracy. The results highlight that DInSAR has the capacity to delineate areas affected by large and sudden deformations and fulfills most of the immediate response requirements. The main limiting factor of interferometry is the availability of suitable SAR acquisition immediately after the event (e.g. Sentinel-1 mission characterized by 6-day revisiting time may not always satisfy the immediate emergency request). PSI and SBAS techniques are suitable to produce

  8. Shuttle Imaging Radar - Geologic applications

    NASA Technical Reports Server (NTRS)

    Macdonald, H.; Bridges, L.; Waite, W.; Kaupp, V.

    1982-01-01

    The Space Shuttle, on its second flight (November 12, 1981), carried the first science and applications payload which provided an early demonstration of Shuttle's research capabilities. One of the experiments, the Shuttle Imaging Radar-A (SIR-A), had as a prime objective to evaluate the capability of spaceborne imaging radars as a tool for geologic exploration. The results of the experiment will help determine the value of using the combination of space radar and Landsat imagery for improved geologic analysis and mapping. Preliminary analysis of the Shuttle radar imagery with Seasat and Landsat imagery from similar areas provides evidence that spaceborne radars can significantly complement Landsat interpretation, and vastly improve geologic reconnaissance mapping in those areas of the world that are relatively unmapped because of perpetual cloud cover.

  9. Terahertz imaging: applications and perspectives.

    PubMed

    Jansen, Christian; Wietzke, Steffen; Peters, Ole; Scheller, Maik; Vieweg, Nico; Salhi, Mohammed; Krumbholz, Norman; Jördens, Christian; Hochrein, Thomas; Koch, Martin

    2010-07-01

    Terahertz (THz) spectroscopy, and especially THz imaging, holds large potential in the field of nondestructive, contact-free testing. The ongoing advances in the development of THz systems, as well as the appearance of the first related commercial products, indicate that large-scale market introduction of THz systems is rapidly approaching. We review selected industrial applications for THz systems, comprising inline monitoring of compounding processes, plastic weld joint inspection, birefringence analysis of fiber-reinforced components, water distribution monitoring in polymers and plants, as well as quality inspection of food products employing both continuous wave and pulsed THz systems.

  10. Planning applications in image analysis

    NASA Technical Reports Server (NTRS)

    Boddy, Mark; White, Jim; Goldman, Robert; Short, Nick, Jr.

    1994-01-01

    We describe two interim results from an ongoing effort to automate the acquisition, analysis, archiving, and distribution of satellite earth science data. Both results are applications of Artificial Intelligence planning research to the automatic generation of processing steps for image analysis tasks. First, we have constructed a linear conditional planner (CPed), used to generate conditional processing plans. Second, we have extended an existing hierarchical planning system to make use of durations, resources, and deadlines, thus supporting the automatic generation of processing steps in time and resource-constrained environments.

  11. Bayes classification of interferometric TOPSAR data

    NASA Technical Reports Server (NTRS)

    Michel, T. R.; Rodriguez, E.; Houshmand, B.; Carande, R.

    1995-01-01

    We report the Bayes classification of terrain types at different sites using airborne interferometric synthetic aperture radar (INSAR) data. A Gaussian maximum likelihood classifier was applied on multidimensional observations derived from the SAR intensity, the terrain elevation model, and the magnitude of the interferometric correlation. Training sets for forested, urban, agricultural, or bare areas were obtained either by selecting samples with known ground truth, or by k-means clustering of random sets of samples uniformly distributed across all sites, and subsequent assignments of these clusters using ground truth. The accuracy of the classifier was used to optimize the discriminating efficiency of the set of features that was chosen. The most important features include the SAR intensity, a canopy penetration depth model, and the terrain slope. We demonstrate the classifier's performance across sites using a unique set of training classes for the four main terrain categories. The scenes examined include San Francisco (CA) (predominantly urban and water), Mount Adams (WA) (forested with clear cuts), Pasadena (CA) (urban with mountains), and Antioch Hills (CA) (water, swamps, fields). Issues related to the effects of image calibration and the robustness of the classification to calibration errors are explored. The relative performance of single polarization Interferometric data classification is contrasted against classification schemes based on polarimetric SAR data.

  12. Nonclassical light in interferometric measurements

    NASA Technical Reports Server (NTRS)

    Ansari, N. A.; Difiore, L.; Romano, R.; Solimeno, S.; Zaccaria, F.; Manko, Margarita A.; Manko, Vladimir I.

    1995-01-01

    It is shown that the even and odd coherent light and other nonclassical states of light like superposition of coherent states with different phases may replace the squeezed light in an interferometric gravitational wave detector to increase its sensitivity.

  13. Hyperspectral imaging and its applications

    NASA Astrophysics Data System (ADS)

    Serranti, S.; Bonifazi, G.

    2016-04-01

    Hyperspectral imaging (HSI) is an emerging technique that combines the imaging properties of a digital camera with the spectroscopic properties of a spectrometer able to detect the spectral attributes of each pixel in an image. For these characteristics, HSI allows to qualitatively and quantitatively evaluate the effects of the interactions of light with organic and/or inorganic materials. The results of this interaction are usually displayed as a spectral signature characterized by a sequence of energy values, in a pre-defined wavelength interval, for each of the investigated/collected wavelength. Following this approach, it is thus possible to collect, in a fast and reliable way, spectral information that are strictly linked to chemical-physical characteristics of the investigated materials and/or products. Considering that in an hyperspectral image the spectrum of each pixel can be analyzed, HSI can be considered as one of the best nondestructive technology allowing to perform the most accurate and detailed information extraction. HSI can be applied in different wavelength fields, the most common are the visible (VIS: 400-700 nm), the near infrared (NIR: 1000-1700 nm) and the short wave infrared (SWIR: 1000-2500 nm). It can be applied for inspections from micro- to macro-scale, up to remote sensing. HSI produces a large amount of information due to the great number of continuous collected spectral bands. Such an approach, when successful, is quite challenging being usually reliable, robust and characterized by lower costs, if compared with those usually associated to commonly applied analytical off-line and/or on-line analytical approaches. More and more applications have been thus developed and tested, in these last years, especially in food inspection, with a large range of investigated products, such as fruits and vegetables, meat, fish, eggs and cereals, but also in medicine and pharmaceutical sector, in cultural heritage, in material characterization and in

  14. Interferometric synthetic aperture radar terrain elevation mapping from multiple observations

    SciTech Connect

    Ghiglia, D.C.; Wahl, D.E.

    1994-07-01

    All prior interferometric SAR imaging experiments to date dealt with pairwise processing. Simultaneous image collections from two antenna systems or two-pass single antenna collections are processed as interferometric pairs to extract corresponding pixel by pixel phase differences which encode terrain elevation height. The phase differences are wrapped values which must be unwrapped and scaled to yield terrain height. We propose two major classes of techniques that hold promise for robust multibaseline (multiple pair) interferometric SAR terrain elevation mapping. The first builds on the capability of a recently published method for robust weighted and unweighted least-squares phase unwrapping, while the second attacks the problem directly in a maximum likelihood (ML) formulation. We will provide several examples (actual and simulated SAR imagery) that illustrate the advantages and disadvantages of each method.

  15. Electromagnetic Imaging Methods for Nondestructive Evaluation Applications

    PubMed Central

    Deng, Yiming; Liu, Xin

    2011-01-01

    Electromagnetic nondestructive tests are important and widely used within the field of nondestructive evaluation (NDE). The recent advances in sensing technology, hardware and software development dedicated to imaging and image processing, and material sciences have greatly expanded the application fields, sophisticated the systems design and made the potential of electromagnetic NDE imaging seemingly unlimited. This review provides a comprehensive summary of research works on electromagnetic imaging methods for NDE applications, followed by the summary and discussions on future directions. PMID:22247693

  16. Electromagnetic imaging methods for nondestructive evaluation applications.

    PubMed

    Deng, Yiming; Liu, Xin

    2011-01-01

    Electromagnetic nondestructive tests are important and widely used within the field of nondestructive evaluation (NDE). The recent advances in sensing technology, hardware and software development dedicated to imaging and image processing, and material sciences have greatly expanded the application fields, sophisticated the systems design and made the potential of electromagnetic NDE imaging seemingly unlimited. This review provides a comprehensive summary of research works on electromagnetic imaging methods for NDE applications, followed by the summary and discussions on future directions.

  17. Perceptual Based Image Fusion with Applications to Hyperspectral Image Data.

    DTIC Science & Technology

    1994-12-01

    spectral bands from the AVIRIS hyperspectral sensor will be evaluated. 1.4 Approach/ Thesis Organization Chapter one described data processing problems...Based Image Fusion with Applications to Hyperspectral Image Data THESIS A o .:or \\Terry Allen Wilson NTS _ Captain, USAF DTIC Tf-, LI Unannou!c<ej LI...Applications to Hyperspectral Image Data THESIS Presented to the Faculty of the Graduate School of Engineering of the Air Force Institute of

  18. Interferometric spectropolarimetry: alternate experimental methods.

    PubMed

    Fymat, A L

    1972-10-01

    Three alternate methods of obtaining spectra of the intensity and state of polarization of light are proposed. The methods make use of a two-beam amplitude division interferometer using the technique of Fourier spectroscopy. They can be applied to either emerging beam, source beam, or detector beam r to both. They do not require the presence of polarizers in the arms of the instrument. In one method (Method 2) a single analyzer is used in front of the detector with three successive orientations of its transmission axis azimuth (0 degrees , 45 degrees , 90 degrees ). In another method (Method 3) a (linear) polarizer assuming the same set of orientations is placed in the incident beam. A third method (Method 4), a hybrid of the former two methods, makes use of both a polarizer and an analyzer in the locations indicated. The latter method presents itself three alternate possibilities. Method 2 permits the determination of all four Stokes parameters of polarization, whereas Methods 3 and 4 cannot yield the ellipticity parameter. All methods require the recording of three interferograms. However, two interferograms can provide the intensity and degree of polarization in any of the methods described. The theory of our earlier method (Method 1, Fymat and Abhyankar, 1970) is also established more rigorously concerning the proposed interferometric arrangements, the applicability of the method to the source beam, and the possibility of deriving the orientation of the plane of polarization and the ellipticity from a single interferogram.

  19. uvmcmcfit: Parametric models to interferometric data fitter

    NASA Astrophysics Data System (ADS)

    Bussmann, Shane; Leung, Tsz Kuk (Daisy); Conley, Alexander

    2016-06-01

    Uvmcmcfit fits parametric models to interferometric data. It is ideally suited to extract the maximum amount of information from marginally resolved observations with interferometers like the Atacama Large Millimeter Array (ALMA), Submillimeter Array (SMA), and Plateau de Bure Interferometer (PdBI). uvmcmcfit uses emcee (ascl:1303.002) to do Markov Chain Monte Carlo (MCMC) and can measure the goodness of fit from visibilities rather than deconvolved images, an advantage when there is strong gravitational lensing and in other situations. uvmcmcfit includes a pure-Python adaptation of Miriad’s (ascl:1106.007) uvmodel task to generate simulated visibilities given observed visibilities and a model image and a simple ray-tracing routine that allows it to account for both strongly lensed systems (where multiple images of the lensed galaxy are detected) and weakly lensed systems (where only a single image of the lensed galaxy is detected).

  20. An extensible imaging platform for optical imaging applications

    NASA Astrophysics Data System (ADS)

    Paladini, Gianluca; Azar, Fred S.

    2009-02-01

    The National Institutes of Health (NIH) has recently developed an extensible imaging platform (XIP), a new open-source software development platform. XIP can be used to rapidly develop imaging applications designed to meet the needs of the optical imaging community. XIP is a state-of-the-art set of visual 'drag and drop' programming tools and associated libraries for rapid prototyping and application development. The tools include modules tailored for medical imaging, many of which are GPU hardware accelerated. They also provide a friendlier environment for utilizing popular toolkits such as ITK and VTK, and enable the visualization and processing of optical imaging data and standard DICOM data. XIP has built-in functionality for multidimensional data visualization and processing, and enables the development of independently optimized and re-usable software modules, which can be seamlessly added and interconnected to build advanced applications. XIP applications can run "stand alone", including in client/server mode for remote access. XIP also supports the DICOM WG23 "Application Hosting" standard, which will enable plug-in XIP applications to run on any DICOM host workstation. Such interoperability will enable the optical imaging community to develop and deploy modular applications across all academic/clinical/industry partners with WG23 compliant imaging workstations.

  1. A geometry-based image search engine for advanced RADARSAT-1/2 GIS applications

    NASA Astrophysics Data System (ADS)

    Kotamraju, Vinay; Rabus, Bernhard; Busler, Jennifer

    2012-06-01

    Space-borne Synthetic Aperture Radar (SAR) sensors, such as RADARSAT-1 and -2, enable a multitude of defense and security applications owing to their unique capabilities of cloud penetration, day/night imaging and multi-polarization imaging. As a result, advanced SAR image time series exploitation techniques such as Interferometric SAR (InSAR) and Radargrammetry are now routinely used in applications such as underground tunnel monitoring, infrastructure monitoring and DEM generation. Imaging geometry, as determined by the satellite orbit and imaged terrain, plays a critical role in the success of such techniques. This paper describes the architecture and the current status of development of a geometry-based search engine that allows the search and visualization of archived and future RADARSAT-1 and -2 images appropriate for a variety of advanced SAR techniques and applications. Key features of the search engine's scalable architecture include (a) Interactive GIS-based visualization of the search results; (b) A client-server architecture for online access that produces up-to-date searches of the archive images and that can, in future, be extended to acquisition planning; (c) A techniquespecific search mode, wherein an expert user explicitly sets search parameters to find appropriate images for advanced SAR techniques such as InSAR and Radargrammetry; (d) A future application-specific search mode, wherein all search parameters implicitly default to preset values according to the application of choice such as tunnel monitoring, DEM generation and deformation mapping; (f) Accurate baseline calculations for InSAR searches, and, optimum beam configuration for Radargrammetric searches; (g) Simulated quick look images and technique-specific sensitivity maps in the future.

  2. Interferometric radar measurements

    NASA Astrophysics Data System (ADS)

    Smith, Ronald A.; Shipman, Mark; Holder, E. J.; Williams, James K.

    2002-08-01

    The United States Army Space and Missile Defense Command (USASMDC) has interest in a technology demonstration that capitalizes on investment in fire control and smart interceptor technologies that have matured beyond basic research. The concept SWORD (Short range missile defense With Optimized Radar Distribution) consists of a novel approach utilizing a missile interceptor and interferometric fire control radar. A hit-to-kill, closed-loop, command guidance scheme is planned that takes advantage of extremely accurate target and interceptor state vectors derived via the fire control radar. The fire control system has the capability to detect, track, and classify multiple threats in a tactical regime as well as simultaneously provide command guidance updates to multiple missile interceptors. The missile interceptor offers a cost reduction potential as well as an enhancement to the kinematics range and lethality over existing SHORAD systems. Additionally, the Radio Frequency (RF) guidance scheme offers increased battlefield weather performance. The Air Defense (AD) community, responding to current threat capabilities and trends, has identified an urgent need to have a capability to counter proliferated, low cost threats with a low cost-per-kill weapon system. The SWORD system will offer a solution that meets this need. The SWORD critical technologies will be identified including a detailed description of each. Validated test results and basic principles of operation will be presented to prove the merit of past investments. The Deputy Assistant Secretary of the Army for Research and Technology (DAS(R&T) has a three- year Science and Technology Program to evaluate the errors and proposed mitigation techniques associated with target spectral dispersion and range gate straddle. Preliminary bench-top experiment results will be presented in this paper.

  3. Molecular imaging applications for immunology.

    PubMed

    Hildebrandt, Isabel Junie; Gambhir, Sanjiv Sam

    2004-05-01

    The use of multimodality molecular imaging has recently facilitated the study of molecular and cellular events in living subjects in a noninvasive and repetitive manner to improve the diagnostic capability of traditional assays. The noninvasive imaging modalities utilized for both small animal and human imaging include positron emission tomography (PET), single photon emission computed tomography (SPECT), magnetic resonance imaging (MRI), ultrasound, and computed tomography (CT). Techniques specific to small-animal imaging include bioluminescent imaging (BIm) and fluorescent imaging (FIm). Molecular imaging permits the study of events within cells, the examination of cell trafficking patterns that relate to inflammatory diseases and metastases, and the ability to rapidly screen new drug treatments for distribution and effectiveness. In this paper, we will review the current field of molecular imaging assays (especially those utilizing PET and BIm modalities) and examine how they might impact animal models and human disease in the field of clinical immunology.

  4. Imaging Strategies for Tissue Engineering Applications

    PubMed Central

    Nam, Seung Yun; Ricles, Laura M.; Suggs, Laura J.

    2015-01-01

    Tissue engineering has evolved with multifaceted research being conducted using advanced technologies, and it is progressing toward clinical applications. As tissue engineering technology significantly advances, it proceeds toward increasing sophistication, including nanoscale strategies for material construction and synergetic methods for combining with cells, growth factors, or other macromolecules. Therefore, to assess advanced tissue-engineered constructs, tissue engineers need versatile imaging methods capable of monitoring not only morphological but also functional and molecular information. However, there is no single imaging modality that is suitable for all tissue-engineered constructs. Each imaging method has its own range of applications and provides information based on the specific properties of the imaging technique. Therefore, according to the requirements of the tissue engineering studies, the most appropriate tool should be selected among a variety of imaging modalities. The goal of this review article is to describe available biomedical imaging methods to assess tissue engineering applications and to provide tissue engineers with criteria and insights for determining the best imaging strategies. Commonly used biomedical imaging modalities, including X-ray and computed tomography, positron emission tomography and single photon emission computed tomography, magnetic resonance imaging, ultrasound imaging, optical imaging, and emerging techniques and multimodal imaging, will be discussed, focusing on the latest trends of their applications in recent tissue engineering studies. PMID:25012069

  5. Imaging strategies for tissue engineering applications.

    PubMed

    Nam, Seung Yun; Ricles, Laura M; Suggs, Laura J; Emelianov, Stanislav Y

    2015-02-01

    Tissue engineering has evolved with multifaceted research being conducted using advanced technologies, and it is progressing toward clinical applications. As tissue engineering technology significantly advances, it proceeds toward increasing sophistication, including nanoscale strategies for material construction and synergetic methods for combining with cells, growth factors, or other macromolecules. Therefore, to assess advanced tissue-engineered constructs, tissue engineers need versatile imaging methods capable of monitoring not only morphological but also functional and molecular information. However, there is no single imaging modality that is suitable for all tissue-engineered constructs. Each imaging method has its own range of applications and provides information based on the specific properties of the imaging technique. Therefore, according to the requirements of the tissue engineering studies, the most appropriate tool should be selected among a variety of imaging modalities. The goal of this review article is to describe available biomedical imaging methods to assess tissue engineering applications and to provide tissue engineers with criteria and insights for determining the best imaging strategies. Commonly used biomedical imaging modalities, including X-ray and computed tomography, positron emission tomography and single photon emission computed tomography, magnetic resonance imaging, ultrasound imaging, optical imaging, and emerging techniques and multimodal imaging, will be discussed, focusing on the latest trends of their applications in recent tissue engineering studies.

  6. Brain Imaging: Applications in Psychiatry.

    ERIC Educational Resources Information Center

    Andreasen, Nancy C.

    1988-01-01

    Discusses various brain imaging techniques, including computed tomography, magnetic resonance imaging, measurement of regional cerebral blood flow, single photo emission tomography, and position emission tomography. Describes the uses of these techniques in helping to understand brain functioning. (TW)

  7. Brain Imaging: Applications in Psychiatry.

    ERIC Educational Resources Information Center

    Andreasen, Nancy C.

    1988-01-01

    Discusses various brain imaging techniques, including computed tomography, magnetic resonance imaging, measurement of regional cerebral blood flow, single photo emission tomography, and position emission tomography. Describes the uses of these techniques in helping to understand brain functioning. (TW)

  8. Applications of condensed dynamic images

    SciTech Connect

    Klein, H.A.

    1986-03-01

    In appropriate cases, information from a dynamic series of nuclear images may be condensed into a single image with one spatial and one temporal dimension. A useful elaboration of the method consists of the masking out of undesired spatial regions. The versatility of such condensed dynamic images is illustrated by examples derived from gastroesophageal and pulmonary studies. Advantages of the method include obviating the need to examine and comprehend multiple images as well as enabling economical archiving of image data. Its diagnostic potential is particularly evident in esophageal transit and infant gastroesophageal reflux studies.

  9. Digital imaging and video: principles and applications.

    PubMed

    Rosen, Andrew L; Hausman, Michael

    2003-01-01

    Digital imaging has provided orthopaedic surgeons with new, powerful tools that offer a multitude of applications. Already integral to several common medical devices, digital images can be used for case documentation and presentation as well as for diagnostic and surgical patient care information. Educational presentation has been transformed by the use of computers and digital projectors. Understanding the basic foundations of digital imaging technology is important for effectively creating digital images, videos, and presentations.

  10. Principles and clinical applications of image analysis.

    PubMed

    Kisner, H J

    1988-12-01

    Image processing has traveled to the lunar surface and back, finding its way into the clinical laboratory. Advances in digital computers have improved the technology of image analysis, resulting in a wide variety of medical applications. Offering improvements in turnaround time, standardized systems, increased precision, and walkaway automation, digital image analysis has likely found a permanent home as a diagnostic aid in the interpretation of microscopic as well as macroscopic laboratory images.

  11. Computerized interferometric surface measurements [Invited].

    PubMed

    Wyant, James C

    2013-01-01

    The addition of electronics, computers, and software to interferometry has enabled enormous improvements in optical metrology. This paper discusses four areas in which computerized interferometric measurement improvements have been made in the measurement of surface shape and surface roughness: (a) The use of computer-generated holograms for the testing of aspheric optics, (b) phase-shifting interferometry for getting interferometric data into a computer so the data can be analyzed, (c) computerized interference microscopes, including multiple-wavelength and coherence scanning, for the precision measurement of surface microstructure, and (d) vibration-insensitive dynamic interferometers for enabling precise measurements in noncontrolled environments.

  12. Mobile radio interferometric geodetic systems

    NASA Technical Reports Server (NTRS)

    Macdoran, P. F.; Niell, A. E.; Ong, K. M.; Resch, G. M.; Morabito, D. D.; Claflin, E. S.; Lockhart, T. G.

    1978-01-01

    Operation of the Astronomical Radio Interferometric Earth Surveying (ARIES) in a proof of concept mode is discussed. Accuracy demonstrations over a short baseline, a 180 km baseline, and a 380 km baseline are documented. Use of ARIES in the Sea Slope Experiment of the National Geodetic Survey to study the apparent differences between oceanographic and geodetic leveling determinations of the sea surface along the Pacific Coast is described. Intergration of the NAVSTAR Global Positioning System and a concept called SERIES (Satellite Emission Radio Interferometric Earth Surveying) is briefly reviewed.

  13. New applications of Spectral Edge image fusion

    NASA Astrophysics Data System (ADS)

    Hayes, Alex E.; Montagna, Roberto; Finlayson, Graham D.

    2016-05-01

    In this paper, we present new applications of the Spectral Edge image fusion method. The Spectral Edge image fusion algorithm creates a result which combines details from any number of multispectral input images with natural color information from a visible spectrum image. Spectral Edge image fusion is a derivative-based technique, which creates an output fused image with gradients which are an ideal combination of those of the multispectral input images and the input visible color image. This produces both maximum detail and natural colors. We present two new applications of Spectral Edge image fusion. Firstly, we fuse RGB-NIR information from a sensor with a modified Bayer pattern, which captures visible and near-infrared image information on a single CCD. We also present an example of RGB-thermal image fusion, using a thermal camera attached to a smartphone, which captures both visible and low-resolution thermal images. These new results may be useful for computational photography and surveillance applications.

  14. New formulation for interferometric synthetic aperture radar for terrain mapping

    SciTech Connect

    Jakowatz, C.V. Jr.; Wahl, D.E.; Eichel, P.H.; Thompson, P.A.

    1994-04-01

    The subject of interferometric synthetic aperture radar (IFSAR) for high-accuracy terrain elevation mapping continues to gain importance in the arena of radar signal processing. Applications to problems in precision terrain-aided guidance and automatic target recognition, as well as a variety of civil applications, are being studied by a number of researchers. Not unlike many other areas of SAR processing, the subject of IFSAR can at first glance appear to be somewhat mysterious. In this paper we show how the mathematics of IFSAR for terrain elevation mapping using a pair of spotlight mode SAR collections can be derived in a very straightforward manner. Here, we employ an approach that relies entirely on three-dimensional Fourier transforms, and utilizes no reference to range equations or Doppler concepts. The result is a simplified explanation of the fundamentals of interferometry, including an easily-seen link between image domain phase difference and terrain elevation height. The derivation builds upon previous work by the authors in which a framework for spotlight mode SAR image formation based on an analogy to three-dimensional computerized axial tomography (CAT) was developed. After outlining the major steps in the mathematics, we show how a computer simulator which utilizes three-dimensional Fourier transforms can be constructed that demonstrates all of the major aspects of IFSAR from spotlight mode collections.

  15. Monitoring Surface Deformation using Polarimetric Ground Based Interferometric Radar

    NASA Astrophysics Data System (ADS)

    Legarsky, J. J.; Gomez, F.; Rosenblad, B.; Loehr, E.; Cherukumilli, S.; Deng, H.; Held, B.; Jenkins, W.

    2012-12-01

    Surface deformation monitoring using ground based interferometric radar (GBIR) measurements may be desirable for a number of applications in the earth sciences. The University of Missouri (MU) research team has ongoing efforts to use the MU GBIR for monitoring surface deformation at a number of sites. Measurements have been collected at sites requiring access by various transportation means such as using off-road vehicle, hiking, and helicopter. Once on site, initial setup takes about 10 minutes. After setup, an image may be acquired by azimuth scan about every 20 seconds. The highly portable system lends itself to rapid deployment in remote environments and repeat survey sites. The MU GBIR's high portability and fast imaging capabilities allow rapid surveying and long-term surveying potential of surface deformation. Imagery may be formed in near real time for initial quick looks. After data collection, imagery data may be further enhanced by radiometric calibration, polarimetric calibration, and time-series analysis. Imaging may be acquired at the electromagnetic spectral bands of C-band and Ku-band. Prior demonstration of millimeter and better sensitivity to deformation over the course of a day of data collects has been performed using the MU GBIR. In addition, the MU GBIR can be removed and re-positioned at the same point with geodetic-grade precision for repeat surveys. Study results and additional development progress will be presented. This project is sponsored by a grant from the National Science Foundation.

  16. State-of-art pulsar studies using interferometric arrays

    NASA Astrophysics Data System (ADS)

    Roy, Jayanta

    The new flexible and powerful software back-end (GSB) opens up the possibility of new regimes of pulsar studies with interferometric arrays like the GMRT, as exemplified by two unique techniques - a gating correlator for millisecond pulsars (MSPs) and a multi-pixel beamformer. We have developed a coherently dedispersed MSP gating correlator at the GMRT motivated by the requirement of localising the newly discovered faint Fermi MSPs. This imaging technique uses the dedispersed visibility data folded with period, acceleration and jerk. We could localise the tighter and fainter binary MSPs in the ON-OFF image plane, even outside the HPBW of GMRT. This tool enables study of unique aspects of MSP population (also pulsars in general) using present and up-coming interferometric arrays (LEAP, ASKAP, MeerKAT, SKA etc). Study the off-pulse emission from the gamma-ray selected MSPs using the MSP gating imaging technique can provide additional constrain on the emission region in pulsar magnetosphere. Moreover, proper motion study of the fainter pulsars is highly benefited from the sensitivity enhancement on the gated image plane. We have also developed a multi-pixel beamformer technique, which is able to look for pulsations much more efficiently over a larger solid angle. This efficient technique combines the enhanced sensitivity of a coherent array beamformer with the wide field-of-view seen by an incoherent array beamformer. I will present a special application of this technique, where we use continuum imaging followed by the multi-pixel beamformer to obtain the precise locations of newly discovered MSPs with the GMRT. Accurate positions measured with single observations enable highly sensitive follow-up studies using coherent array beamformer and rapid follow up at higher radio frequencies and other wavelengths. Normally, such accurate positions can only be obtained from a long-term pulsar timing program. The multi-pixel beamformer technique can also be used for highly

  17. Terahertz Imaging and Security Applications

    NASA Astrophysics Data System (ADS)

    Grossman, Erich

    2005-03-01

    Imaging at millimeter-wave and terahertz frequencies could vastly improve the security of personnel checkpoints, because of the penetration through clothing and spatial resolution available in this spectral range. Since 9/11, the social need for improved checkpoint screening has been obvious and great. However, although efforts to develop such imagers had been underway for many years before that, practical low-cost systems, analogous to IR uncooled imagers, still don't exist. An emphasis on purely passive imaging places very stringent sensitivity requirements on such imagers. A number of long-term efforts, which I briefly mention, are underway to improve the sensitivity of such passive imagers. However, most of the emphasis in our program is on active imaging. With this approach, much simpler and lower-cost detectors, such as (uncooled) antenna-coupled microbolometers can be used, at the expense of incorporating slightly more complex optics and illumination components. I discuss several tradeoffs presented in the design of active imaging systems for the 100 to 1000 GHz frequency range, describe how we have addressed them in the design of a scanning, 95 GHz, bolometer-based imager for concealed weapons detection that is nearing completion, and describe how the system architecture can be modified to scale the operating frequency to the 650 GHz atmospheric window. Co-authors: Arttu Luukanen and Aaron Miller

  18. Recent Applications of Neutron Imaging Methods

    NASA Astrophysics Data System (ADS)

    Lehmann, E.; Mannes, D.; Kaestner, A.; Grünzweig, C.

    The methodical progress in the field of neutron imaging is visible in general but on different levels in the particular labs. Consequently, the access to most suitable beam ports, the usage of advanced imaging detector systems and the professional image processing made the technique competitive to other non-destructive tools like X-ray imaging. Based on this performance gain and by new methodical approaches several new application fields came up - in addition to the already established ones. Accordingly, new image data are now mostly in the third dimension available in the format of tomography volumes. The radiography mode is still the basis of neutron imaging, but the extracted information from superimposed image data (like for a grating interferometer) enables completely new insights. In the consequence, many new applications were created.

  19. Petrophysical applications of NMR imaging

    SciTech Connect

    Rothwell, W.P.; Vinegar, H.J.

    1985-12-01

    A system for obtaining high-resolution NMR images of oil field cores is described. Separate proton density and T/sub 2/ relaxation images are obtained to distinguish spatial variations of fluid-filled porosity and the physical nature of the pores. Results are presented for typical sandstones.

  20. Two-Wavelength Interferometric Keratometer

    NASA Technical Reports Server (NTRS)

    Hochberg, Eric; Page, Norman

    1991-01-01

    Proposed interferometric keratometer measures shapes of corneas without touching them. Used to test strongly aspherical optics. Resembling present commercial lens-testing interferometers, generates interferograms representative of deviation of surfaces under test from sphericity. Such interferograms used to generate contour maps of surfaces. Measures corneal topography to diameters as large as 12 mm.

  1. Passive terahertz imaging for security application

    NASA Astrophysics Data System (ADS)

    Guo, Lan-tao; Deng, Chao; Zhao, Yuan-meng; Zhang, Cun-lin

    2013-08-01

    The passive detection is safe for passengers and operators as no radiation. Therefore, passive terahertz (THz) imaging can be applied to human body security check. Imaging in the THz band offers the unique property of being able to identify object through a range of materials. Therefore passive THz imaging is meaningful for security applications. This attribute has always been of interest to both the civil and military marks with applications. We took advantage of a single THz detector and a trihedral scanning mirror to propose another passive THz beam scanning imaging method. This method overcame the deficiencies of the serious decline in image quality due to the movement of the focused mirror. We exploited a THz scanning mirror with a trihedral scanning mirror and an ellipsoidal mirror to streamline the structure of the system and increase the scanning speed. Then the passive THz beam scanning imaging system was developed based on this method. The parameters were set as follows: the best imaging distance was 1.7m, the image height was 2m, the image width was 1m, the minimum imaging time of per frame was 8s, and the minimum resolution was 4cm. We imaged humans with different objects hidden under their clothes, such as fruit knife, belt buckle, mobile phone, screwdriver, bus cards, keys and other items. All the tested stuffs could be detected and recognized from the image.

  2. Graph theory for analyzing pair-wise data: application to geophysical model parameters estimated from interferometric synthetic aperture radar data at Okmok volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Reinisch, Elena C.; Cardiff, Michael; Feigl, Kurt L.

    2017-01-01

    Graph theory is useful for analyzing time-dependent model parameters estimated from interferometric synthetic aperture radar (InSAR) data in the temporal domain. Plotting acquisition dates (epochs) as vertices and pair-wise interferometric combinations as edges defines an incidence graph. The edge-vertex incidence matrix and the normalized edge Laplacian matrix are factors in the covariance matrix for the pair-wise data. Using empirical measures of residual scatter in the pair-wise observations, we estimate the relative variance at each epoch by inverting the covariance of the pair-wise data. We evaluate the rank deficiency of the corresponding least-squares problem via the edge-vertex incidence matrix. We implement our method in a MATLAB software package called GraphTreeTA available on GitHub (https://github.com/feigl/gipht). We apply temporal adjustment to the data set described in Lu et al. (Geophys Res Solid Earth 110, 2005) at Okmok volcano, Alaska, which erupted most recently in 1997 and 2008. The data set contains 44 differential volumetric changes and uncertainties estimated from interferograms between 1997 and 2004. Estimates show that approximately half of the magma volume lost during the 1997 eruption was recovered by the summer of 2003. Between June 2002 and September 2003, the estimated rate of volumetric increase is (6.2 ± 0.6) × 10^6 m^3/year . Our preferred model provides a reasonable fit that is compatible with viscoelastic relaxation in the five years following the 1997 eruption. Although we demonstrate the approach using volumetric rates of change, our formulation in terms of incidence graphs applies to any quantity derived from pair-wise differences, such as range change, range gradient, or atmospheric delay.

  3. Image registration for luminescent paint applications

    NASA Technical Reports Server (NTRS)

    Bell, James H.; Mclachlan, Blair G.

    1993-01-01

    The use of pressure sensitive luminescent paints is a viable technique for the measurement of surface pressure on wind tunnel models. This technique requires data reduction of images obtained under known as well as test conditions and spatial transformation of the images. A general transform which registers images to subpixel accuracy is presented and the general characteristics of transforms for image registration and their derivation are discussed. Image resection and its applications are described. The mapping of pressure data to the three dimensional model surface for small wind tunnel models to a spatial accuracy of 0.5 percent of the model length is demonstrated.

  4. Medical applications of microwave imaging.

    PubMed

    Wang, Zhao; Lim, Eng Gee; Tang, Yujun; Leach, Mark

    2014-01-01

    Ultrawide band (UWB) microwave imaging is a promising method for the detection of early stage breast cancer, based on the large contrast in electrical parameters between malignant tumour tissue and the surrounding normal breast-tissue. In this paper, the detection and imaging of a malignant tumour are performed through a tomographic based microwave system and signal processing. Simulations of the proposed system are performed and postimage processing is presented. Signal processing involves the extraction of tumour information from background information and then image reconstruction through the confocal method delay-and-sum algorithms. Ultimately, the revision of time-delay and the superposition of more tumour signals are applied to improve accuracy.

  5. CMOS imager for pointing and tracking applications

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata (Inventor); Sun, Chao (Inventor); Yang, Guang (Inventor); Heynssens, Julie B. (Inventor)

    2006-01-01

    Systems and techniques to realize pointing and tracking applications with CMOS imaging devices. In general, in one implementation, the technique includes: sampling multiple rows and multiple columns of an active pixel sensor array into a memory array (e.g., an on-chip memory array), and reading out the multiple rows and multiple columns sampled in the memory array to provide image data with reduced motion artifact. Various operation modes may be provided, including TDS, CDS, CQS, a tracking mode to read out multiple windows, and/or a mode employing a sample-first-read-later readout scheme. The tracking mode can take advantage of a diagonal switch array. The diagonal switch array, the active pixel sensor array and the memory array can be integrated onto a single imager chip with a controller. This imager device can be part of a larger imaging system for both space-based applications and terrestrial applications.

  6. Small pixel uncooled imaging FPAs and applications

    NASA Astrophysics Data System (ADS)

    Blackwell, Richard; Franks, Glen; Lacroix, Daniel; Hyland, Sandra; Murphy, Robert

    2010-04-01

    BAE Systems continues to make dramatic progress in uncooled microbolometer sensors and applications. This paper will review the latest advancements in microbolometer technology at BAE Systems, including the development status of 17 micrometer pixel pitch detectors and imaging modules which are entering production and will be finding their way into BAE Systems products and applications. Benefits include increased die per wafer and potential benefits to SWAP for many applications. Applications include thermal weapons sights, thermal imaging modules for remote weapon stations, vehicle situational awareness sensors and mast/pole mounted sensors.

  7. Advances in scintillators for medical imaging applications

    NASA Astrophysics Data System (ADS)

    van Loef, Edgar V.; Shah, Kanai S.

    2014-09-01

    A review is presented of some recent work in the field of inorganic scintillator research for medical imaging applications, in particular scintillation detectors for Single-Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET).

  8. Image informatics in systems biology applications

    NASA Astrophysics Data System (ADS)

    Wong, Stephen T. C.

    2005-02-01

    Digital optical microscopy, coupled with parallel processing and a large arsenal of labeling techniques, offers tremendous values to localize, identify, and characterize cells and molecules. This generates many image informatics challenges in requiring new algorithms and tools to extract, classify, correlate, and model image features and content from massive amounts of cellular and molecular images acquired. Image informatics aims to fill this gap. Coupling automated microscopy and image analysis with biostatistical and data mining techniques to provide a system biologic approach in studying the cells, the basic unit of life, potentially leads to many exciting applications in life and health sciences. In this presentation, we describe certain new system biology applications enabled by image informatics technology.

  9. NMR imaging techniques and applications: A review

    NASA Astrophysics Data System (ADS)

    Bottomley, Paul A.

    1982-09-01

    Over the past ten years, a variety of techniques have been proposed and demonstrated that enable the spatial discrimination and mapping of nuclear-magnetic-resonance (NMR) signals in heterogeneous objects. These NMR imaging techniques are currently finding useful application in clinical medicine and physiological chemistry, where their noninvasive, apparently hazard-free nature, and the sensitivity of the NMR signal to the state of biological tissue, are key advantages. This article reviews the historical development, the conceptual basis, and the applications of the various NMR imaging techniques. Qualitative descriptions and illustrations of each technique and an outline of imaging instrumentation are provided. Proton NMR imaging, in medicine, of pathological states such as cancer, imaging of relaxation time, chemical shift and flow parameters, imaging of nuclei other than hydrogen, and potential hazards are discussed and demonstrated with examples.

  10. Secure space-to-space interferometric communications and its nexus to the physics of quantum entanglement

    NASA Astrophysics Data System (ADS)

    Duarte, F. J.

    2016-12-01

    The history of the probability amplitude equation |ψ>=(|x ,y >-|y ,x >) applicable to quanta pairs, propagating in different directions with entangled polarizations, is reviewed and traced back to the 1947-1949 period. The interferometric Dirac foundations common to |ψ>=(|x ,y >-|y ,x >) and the generalized N-slit interferometric equation, for indistinguishable quanta, are also described. The results from a series of experiments on N-slit laser interferometers, with intra interferometric propagation paths up to 527 m, are reviewed. Particular attention is given to explain the generation of interferometric characters, for secure space-to-space communications, which immediately collapse on attempts of interception. The design of a low divergence N-slit laser interferometer for low Earth orbit-low Earth orbit (LEO-LEO), and LEO-geostationary Earth orbit (LEO-GEO), secure interferometric communications is described and a weight assessment is provided.

  11. Interferometric synthetic aperture radar imagery of the Gulf Stream

    NASA Technical Reports Server (NTRS)

    Ainsworth, T. L.; Cannella, M. E.; Jansen, R. W.; Chubb, S. R.; Carande, R. E.; Foley, E. W.; Goldstein, R. M.; Valenzuela, G. R.

    1993-01-01

    The advent of interferometric synthetic aperture radar (INSAR) imagery brought to the ocean remote sensing field techniques used in radio astronomy. Whilst details of the interferometry differ between the two fields, the basic idea is the same: Use the phase information arising from positional differences of the radar receivers and/or transmitters to probe remote structures. The interferometric image is formed from two complex synthetic aperture radar (SAR) images. These two images are of the same area but separated in time. Typically the time between these images is very short -- approximately 50 msec for the L-band AIRSAR (Airborne SAR). During this short period the radar scatterers on the ocean surface do not have time to significantly decorrelate. Hence the two SAR images will have the same amplitude, since both obtain the radar backscatter from essentially the same object. Although the ocean surface structure does not significantly decorrelate in 50 msec, surface features do have time to move. It is precisely the translation of scattering features across the ocean surface which gives rise to phase differences between the two SAR images. This phase difference is directly proportional to the range velocity of surface scatterers. The constant of proportionality is dependent upon the interferometric mode of operation.

  12. Industrial applications of process imaging and image processing

    NASA Astrophysics Data System (ADS)

    Scott, David M.; Sunshine, Gregg; Rosen, Lou; Jochen, Ed

    2001-02-01

    Process imaging is the art of visualizing events inside closed industrial processes. Image processing is the art of mathematically manipulating digitized images to extract quantitative information about such processes. Ongoing advances in camera and computer technology have made it feasible to apply these abilities to measurement needs in the chemical industry. To illustrate the point, this paper describes several applications developed at DuPont, where a variety of measurements are based on in-line, at-line, and off-line imaging. Application areas include compounding, melt extrusion, crystallization, granulation, media milling, and particle characterization. Polymer compounded with glass fiber is evaluated by a patented radioscopic (real-time X-ray imaging) technique to measure concentration and dispersion uniformity of the glass. Contamination detection in molten polymer (important for extruder operations) is provided by both proprietary and commercial on-line systems. Crystallization in production reactors is monitored using in-line probes and flow cells. Granulation is controlled by at-line measurements of granule size obtained from image processing. Tomographic imaging provides feedback for improved operation of media mills. Finally, particle characterization is provided by a robotic system that measures individual size and shape for thousands of particles without human supervision. Most of these measurements could not be accomplished with other (non-imaging) techniques.

  13. Image processing applications in NDE

    SciTech Connect

    Morris, R.A.

    1980-01-01

    Nondestructive examination (NDE) can be defined as a technique or collection of techniques that permits one to determine some property of a material or object without damaging the object. There are a large number of such techniques and most of them use visual imaging in one form or another. They vary from holographic interferometry where displacements under stress are measured to the visual inspection of an objects surface to detect cracks after penetrant has been applied. The use of image processing techniques on the images produced by NDE is relatively new and can be divided into three general categories: classical image enhancement; mensuration techniques; and quantitative sensitometry. An example is discussed of how image processing techniques are used to nondestructively and destructively test the product throughout its life cycle. The product that will be followed is the microballoon target used in the laser fusion program. The laser target is a small (50 to 100 ..mu..m - dia) glass sphere with typical wall thickness of 0.5 to 6 ..mu..m. The sphere may be used as is or may be given a number of coatings of any number of materials. The beads are mass produced by the millions and the first nondestructive test is to separate the obviously bad beads (broken or incomplete) from the good ones. After this has been done, the good beads must be inspected for spherocity and wall thickness uniformity. The microradiography of the glass, uncoated bead is performed on a specially designed low-energy x-ray machine. The beads are mounted in a special jig and placed on a Kodak high resolution plate in a vacuum chamber that contains the x-ray source. The x-ray image is made with an energy less that 2 keV and the resulting images are then inspected at a magnification of 500 to 1000X. Some typical results are presented.

  14. Prior image constrained image reconstruction in emerging computed tomography applications

    NASA Astrophysics Data System (ADS)

    Brunner, Stephen T.

    Advances have been made in computed tomography (CT), especially in the past five years, by incorporating prior images into the image reconstruction process. In this dissertation, we investigate prior image constrained image reconstruction in three emerging CT applications: dual-energy CT, multi-energy photon-counting CT, and cone-beam CT in image-guided radiation therapy. First, we investigate the application of Prior Image Constrained Compressed Sensing (PICCS) in dual-energy CT, which has been called "one of the hottest research areas in CT." Phantom and animal studies are conducted using a state-of-the-art 64-slice GE Discovery 750 HD CT scanner to investigate the extent to which PICCS can enable radiation dose reduction in material density and virtual monochromatic imaging. Second, we extend the application of PICCS from dual-energy CT to multi-energy photon-counting CT, which has been called "one of the 12 topics in CT to be critical in the next decade." Numerical simulations are conducted to generate multiple energy bin images for a photon-counting CT acquisition and to investigate the extent to which PICCS can enable radiation dose efficiency improvement. Third, we investigate the performance of a newly proposed prior image constrained scatter correction technique to correct scatter-induced shading artifacts in cone-beam CT, which, when used in image-guided radiation therapy procedures, can assist in patient localization, and potentially, dose verification and adaptive radiation therapy. Phantom studies are conducted using a Varian 2100 EX system with an on-board imager to investigate the extent to which the prior image constrained scatter correction technique can mitigate scatter-induced shading artifacts in cone-beam CT. Results show that these prior image constrained image reconstruction techniques can reduce radiation dose in dual-energy CT by 50% in phantom and animal studies in material density and virtual monochromatic imaging, can lead to radiation

  15. CMOS Image Sensors for High Speed Applications.

    PubMed

    El-Desouki, Munir; Deen, M Jamal; Fang, Qiyin; Liu, Louis; Tse, Frances; Armstrong, David

    2009-01-01

    Recent advances in deep submicron CMOS technologies and improved pixel designs have enabled CMOS-based imagers to surpass charge-coupled devices (CCD) imaging technology for mainstream applications. The parallel outputs that CMOS imagers can offer, in addition to complete camera-on-a-chip solutions due to being fabricated in standard CMOS technologies, result in compelling advantages in speed and system throughput. Since there is a practical limit on the minimum pixel size (4∼5 μm) due to limitations in the optics, CMOS technology scaling can allow for an increased number of transistors to be integrated into the pixel to improve both detection and signal processing. Such smart pixels truly show the potential of CMOS technology for imaging applications allowing CMOS imagers to achieve the image quality and global shuttering performance necessary to meet the demands of ultrahigh-speed applications. In this paper, a review of CMOS-based high-speed imager design is presented and the various implementations that target ultrahigh-speed imaging are described. This work also discusses the design, layout and simulation results of an ultrahigh acquisition rate CMOS active-pixel sensor imager that can take 8 frames at a rate of more than a billion frames per second (fps).

  16. Balloon-based interferometric techniques

    NASA Technical Reports Server (NTRS)

    Rees, David

    1985-01-01

    A balloon-borne triple-etalon Fabry-Perot Interferometer, observing the Doppler shifts of absorption lines caused by molecular oxygen and water vapor in the far red/near infrared spectrum of backscattered sunlight, has been used to evaluate a passive spaceborne remote sensing technique for measuring winds in the troposphere and stratosphere. There have been two successful high altitude balloon flights of the prototype UCL instrument from the National Scientific Balloon Facility at Palestine, TE (May 80, Oct. 83). The results from these flights have demonstrated that an interferometer with adequate resolution, stability and sensitivity can be built. The wind data are of comparable quality to those obtained from operational techniques (balloon and rocket sonde, cloud-top drift analysis, and from the gradient wind analysis of satellite radiance measurements). However, the interferometric data can provide a regular global grid, over a height range from 5 to 50 km in regions of clear air. Between the middle troposphere (5 km) and the upper stratosphere (40 to 50 km), an optimized instrument can make wind measurements over the daylit hemisphere with an accuracy of about 3 to 5 m/sec (2 sigma). It is possible to obtain full height profiles between altitudes of 5 and 50 km, with 4 km height resolution, and a spatial resolution of about 200 km, along the orbit track. Below an altitude of about 10 km, Fraunhofer lines of solar origin are possible targets of the Doppler wind analysis. Above an altitude of 50 km, the weakness of the backscattered solar spectrum (decreasing air density) is coupled with the low absorption crosssection of all atmospheric species in the spectral region up to 800 nm (where imaging photon detectors can be used), causing the along-the-track resolution (or error) to increase beyond values useful for operational purposes. Within the region of optimum performance (5 to 50 km), however, the technique is a valuable potential complement to existing wind

  17. Computer image processing: Geologic applications

    NASA Technical Reports Server (NTRS)

    Abrams, M. J.

    1978-01-01

    Computer image processing of digital data was performed to support several geological studies. The specific goals were to: (1) relate the mineral content to the spectral reflectance of certain geologic materials, (2) determine the influence of environmental factors, such as atmosphere and vegetation, and (3) improve image processing techniques. For detection of spectral differences related to mineralogy, the technique of band ratioing was found to be the most useful. The influence of atmospheric scattering and methods to correct for the scattering were also studied. Two techniques were used to correct for atmospheric effects: (1) dark object subtraction, (2) normalization of use of ground spectral measurements. Of the two, the first technique proved to be the most successful for removing the effects of atmospheric scattering. A digital mosaic was produced from two side-lapping LANDSAT frames. The advantages were that the same enhancement algorithm can be applied to both frames, and there is no seam where the two images are joined.

  18. Medical Applications of Microwave Imaging

    PubMed Central

    Wang, Zhao; Lim, Eng Gee; Tang, Yujun

    2014-01-01

    Ultrawide band (UWB) microwave imaging is a promising method for the detection of early stage breast cancer, based on the large contrast in electrical parameters between malignant tumour tissue and the surrounding normal breast-tissue. In this paper, the detection and imaging of a malignant tumour are performed through a tomographic based microwave system and signal processing. Simulations of the proposed system are performed and postimage processing is presented. Signal processing involves the extraction of tumour information from background information and then image reconstruction through the confocal method delay-and-sum algorithms. Ultimately, the revision of time-delay and the superposition of more tumour signals are applied to improve accuracy. PMID:25379515

  19. (Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. I. Multiwavelength identifications and redshift distribution

    NASA Astrophysics Data System (ADS)

    Miettinen, O.; Smolčić, V.; Novak, M.; Aravena, M.; Karim, A.; Masters, D.; Riechers, D. A.; Bussmann, R. S.; McCracken, H. J.; Ilbert, O.; Bertoldi, F.; Capak, P.; Feruglio, C.; Halliday, C.; Kartaltepe, J. S.; Navarrete, F.; Salvato, M.; Sanders, D.; Schinnerer, E.; Sheth, K.

    2015-05-01

    We used the Plateau de Bure Interferometer (PdBI) to map a sample of 15 submillimetre galaxies (SMGs) in the COSMOS field at the wavelength of 1.3 mm. The target SMGs were originally discovered in the James Clerk Maxwell Telescope (JCMT)/AzTEC 1.1 mm continuum survey at S/N1.1 mm = 4-4.5. This paper presents, for the first time, interferometric millimetre-wavelength observations of these sources. The angular resolution of our observations, 1''&dotbelow;8, allowed us to accurately determine the positions of the target SMGs. Using a detection threshold of S/N1.3 mm> 4.5 regardless of multiwavelength counterpart association, and 4

  20. System for absolute measurements by interferometric sensors

    NASA Astrophysics Data System (ADS)

    Norton, Douglas A.

    1993-03-01

    The most common problem of interferometric sensors is their inability to measure absolute path imbalance. Presented in this paper is a signal processing system that gives absolute, unambiguous reading of optical path difference for almost any style of interferometric sensor. Key components are a wide band (incoherent) optical source, a polychromator, and FFT electronics. Advantages include no moving parts in the signal processor, no active components at the sensor location, and the use of standard single mode fiber for sensor illumination and signal transmission. Actual absolute path imbalance of the interferometer is determined without using fringe counting or other inferential techniques. The polychromator extracts the interference information that occurs at each discrete wavelength within the spectral band of the optical source. The signal processing consists of analog and digital filtering, Fast Fourier analysis, and a peak detection and interpolation algorithm. This system was originally designed for use in a remote pressure sensing application that employed a totally passive fiber optic interferometer. A performance qualification was made using a Fabry-Perot interferometer and a commercially available laser interferometer to measure the reference displacement.

  1. Interferometric label-free biomolecular detection system

    NASA Astrophysics Data System (ADS)

    Hradetzky, David; Mueller, Claas; Reinecke, Holger

    2006-07-01

    This work presents a simple evanescent wave sensing system based on an interferometric approach, suitable to meet the requirements of label-free sensor systems for detecting biomolecular interactions. It represents a basic concept towards label-free detection systems in various applications. The basic objectives of transducers for evanescent wave sensing are discussed. An optical detection system based on a interferometric approach using Young's double slit configuration is discussed, set-up and characterized. With refractometric measurements of various sucrose dilutions, the performance of the pure optical set-up is evaluated. A mean resolution of the effective refractive index of 3\\sigma (\\overline {\\Delta n}_{\\mathrm {eff}})=0.9 \\times 10^{-6} without averaging was obtained and a reproducibility below σr(neff) = 0.1 × 10-6 was achieved. Furthermore basic experiments were carried out, for proofing the concept's suitability as a highly sensitive biosensor by detecting the hybridization of 21-mer DNA with an immobilized counterpart on the surface.

  2. ENVIRONMENTAL APPLICATIONS OF SPECTRAL IMAGING

    EPA Science Inventory

    The utility of remote sensing using spectral imaging is just being realized through the investigation to a wide variety of environmental issues. Improved spectral and spatial resolution is very important to the detection of effects once regarded as unobservable. A current researc...

  3. A simple image display application for windows.

    PubMed

    Conrad, G R

    1997-08-01

    The purpose of this project was to develop a simple application for displaying low-to-moderate resolution digital images under the Windows operating environment. The display of scintigraphic images was of special interest, and for this reason the program was designed to show sequences of images and to account for broad ranges of pixel values. In order to function under a variety of Windows versions, the program was developed using the 16-bit Microsoft C +2 compiler and targeted for Windows 3.1 enhanced. It was tested with Trionix images for nuclear medicine and Siemens for computed tomography (CT) and magnetic resonance (MR). The resulting application, called SID, successfully read Magnetom, Somatom, Trionix, and Interfile images of dimension 512 or less on Intel-based Windows PCs with 256 color SVGA-compatible (Super Video Graphics Adapters) video hardware. Early applications of the program included remote monitoring of image studies, resident review of teaching cases, review of research images, and preparation of educational materials. This article describes the features, operation, and potential applications of SID.

  4. Fundamentals and applications of magnetic particle imaging.

    PubMed

    Borgert, Jörn; Schmidt, Joachim D; Schmale, Ingo; Rahmer, Jürgen; Bontus, Claas; Gleich, Bernhard; David, Bernd; Eckart, Rainer; Woywode, Oliver; Weizenecker, Jürgen; Schnorr, Jörg; Taupitz, Matthias; Haegele, Julian; Vogt, Florian M; Barkhausen, Jörg

    2012-01-01

    Magnetic particle imaging (MPI) is a new medical imaging technique which performs a direct measurement of magnetic nanoparticles, also known as superparamagnetic iron oxide. MPI can acquire quantitative images of the local distribution of the magnetic material with high spatial and temporal resolution. Its sensitivity is well above that of other methods used for the detection and quantification of magnetic materials, for example, magnetic resonance imaging. On the basis of an intravenous injection of magnetic particles, MPI has the potential to play an important role in medical application areas such as cardiovascular, oncology, and also in exploratory fields such as cell labeling and tracking. Here, we present an introduction to the basic function principle of MPI, together with an estimation of the spatial resolution and the detection limit. Furthermore, the above-mentioned medical applications are discussed with respect to an applicability of MPI.

  5. Intelligent imaging systems for automotive applications

    NASA Astrophysics Data System (ADS)

    Thompson, Chris; Huang, Yingping; Fu, Shan

    2004-03-01

    In common with many other application areas, visual signals are becoming an increasingly important information source for many automotive applications. For several years CCD cameras have been used as research tools for a range of automotive applications. Infrared cameras, RADAR and LIDAR are other types of imaging sensors that have also been widely investigated for use in cars. This paper will describe work in this field performed in C2VIP over the last decade - starting with Night Vision Systems and looking at various other Advanced Driver Assistance Systems. Emerging from this experience, we make the following observations which are crucial for "intelligent" imaging systems: 1. Careful arrangement of sensor array. 2. Dynamic-Self-Calibration. 3. Networking and processing. 4. Fusion with other imaging sensors, both at the image level and the feature level, provides much more flexibility and reliability in complex situations. We will discuss how these problems can be addressed and what are the outstanding issues.

  6. Machine learning applications in cell image analysis.

    PubMed

    Kan, Andrey

    2017-04-04

    Machine learning (ML) refers to a set of automatic pattern recognition methods that have been successfully applied across various problem domains, including biomedical image analysis. This review focuses on ML applications for image analysis in light microscopy experiments with typical tasks of segmenting and tracking individual cells, and modelling of reconstructed lineage trees. After describing a typical image analysis pipeline and highlighting challenges of automatic analysis (for example, variability in cell morphology, tracking in presence of clutters) this review gives a brief historical outlook of ML, followed by basic concepts and definitions required for understanding examples. This article then presents several example applications at various image processing stages, including the use of supervised learning methods for improving cell segmentation, and the application of active learning for tracking. The review concludes with remarks on parameter setting and future directions.Immunology and Cell Biology advance online publication, 4 April 2017; doi:10.1038/icb.2017.16.

  7. Passive millimeter-wave camera with interferometric processing

    NASA Astrophysics Data System (ADS)

    Nohmi, Hitoshi; Ohnishi, Seiki; Kujubu, Osamu

    2006-05-01

    A proto-type passive millimeter-wave (MMW) camera with interferometric processing has been developed. The purpose is to confirm the feasibility of the interferometric MMW camera and to study the characteristics of MMW images. In this paper, the principle and the feature of the interferometric MMW camera is described. Also, the hardware configuration and the image processing algorithm are presented. This proto-type camera is comprised of the minimum configuration as an interferometric imager which consists of two sets of a W-band front end with a horn antenna, a receiver, and an A/D converter, a high-speed processing hardware, and a computer. The position of these two antennas with W-band front-end moves on the precision linear slider in horizontal and vertical axis. The coherently amplified two channel signals are digitized and processed in the hardware processor. The process is comprised of phase error compensation, correlation of all combination of each axis data, and integration to improve the signal to noise ratio. The computer input the integrated data to make an image by matched filter processing. The integration time is from 1mS to 10S depending on required integration gain. The maximum synthesized antenna aperture size is 1m for horizontal axis and 50cm for vertical axis. Because it takes certain time to receive by the moving antennas, only the targets without motion are imaged by this proto-type camera. The processed images will be shown. Also, future plan for a real-time camera using this technique is presented.

  8. Pediatric Electrocardiographic Imaging (ECGI) Applications

    PubMed Central

    Silva, Jennifer N. A.

    2014-01-01

    Summary Noninvasive electrocardiographic imaging (ECGI) has been used in pediatric and congenital heart patients to better understand their electrophysiologic substrates. In this article we focus on the 4 subjects related to pediatric ECGI: 1) ECGI in patients with congenital heart disease and Wolff-Parkinson-White syndrome, 2) ECGI in patients with hypertrophic cardiomyopathy and pre-excitation, 3) ECGI in pediatric patients with Wolff-Parkinson-White syndrome, and 4) ECGI for pediatric cardiac resynchronization therapy. PMID:25722754

  9. True 3d Images and Their Applications

    NASA Astrophysics Data System (ADS)

    Wang, Z.; wang@hzgeospace., zheng.

    2012-07-01

    A true 3D image is a geo-referenced image. Besides having its radiometric information, it also has true 3Dground coordinates XYZ for every pixels of it. For a true 3D image, especially a true 3D oblique image, it has true 3D coordinates not only for building roofs and/or open grounds, but also for all other visible objects on the ground, such as visible building walls/windows and even trees. The true 3D image breaks the 2D barrier of the traditional orthophotos by introducing the third dimension (elevation) into the image. From a true 3D image, for example, people will not only be able to read a building's location (XY), but also its height (Z). true 3D images will fundamentally change, if not revolutionize, the way people display, look, extract, use, and represent the geospatial information from imagery. In many areas, true 3D images can make profound impacts on the ways of how geospatial information is represented, how true 3D ground modeling is performed, and how the real world scenes are presented. This paper first gives a definition and description of a true 3D image and followed by a brief review of what key advancements of geospatial technologies have made the creation of true 3D images possible. Next, the paper introduces what a true 3D image is made of. Then, the paper discusses some possible contributions and impacts the true 3D images can make to geospatial information fields. At the end, the paper presents a list of the benefits of having and using true 3D images and the applications of true 3D images in a couple of 3D city modeling projects.

  10. The Space Infrared Interferometric Telescope (SPIRIT)

    NASA Technical Reports Server (NTRS)

    Leisawitz, David T.

    2014-01-01

    The far-infrared astrophysics community is eager to follow up Spitzer and Herschel observations with sensitive, high-resolution imaging and spectroscopy, for such measurements are needed to understand merger-driven star formation and chemical enrichment in galaxies, star and planetary system formation, and the development and prevalence of water-bearing planets. The Space Infrared Interferometric Telescope (SPIRIT) is a wide field-of-view space-based spatio-spectral interferometer designed to operate in the 25 to 400 micron wavelength range. This talk will summarize the SPIRIT mission concept, with a focus on the science that motivates it and the technology that enables it. Without mentioning SPIRIT by name, the astrophysics community through the NASA Astrophysics Roadmap Committee recently recommended this mission as the first in a series of space-based interferometers. Data from a laboratory testbed interferometer will be used to illustrate how the spatio-spectral interferometry technique works.

  11. Sensitivity errors in interferometric deformation metrology.

    PubMed

    Farrant, David I; Petzing, Jon N

    2003-10-01

    Interferometric measurement techniques such as holographic interferometry and electronic speckle-pattern interferometry are valuable for measuring the deformation of objects. Conventional theoretical models of deformation measurement assume collimated illumination and telecentric imaging, which are usually only practical for small objects. Large objects often require divergent illumination, for which the models are valid only when the object is planar, and then only in the paraxial region. We present an analysis and discussion of the three-dimensional systematic sensitivity errors for both in-plane and out-of-plane interferometer configurations, where it is shown that the errors can be significant. A dimensionless approach is adopted to make the analysis generic and hence scalable to a system of any size.

  12. Simultaneous CARS and Interferometric Rayleigh Scattering

    NASA Technical Reports Server (NTRS)

    Bivolaru, Daniel; Danehy, Paul M.; Grinstead, Keith D., Jr.; Tedder, Sarah; Cutler, Andrew D.

    2006-01-01

    This paper reports for the first time the combination of a dual-pump coherent anti-Stokes Raman scattering system with an interferometric Rayleigh scattering system (CARS - IRS) to provide time-resolved simultaneous measurement of multiple properties in combustion flows. The system uses spectrally narrow green (seeded Nd:YAG at 532 nm) and yellow (552.9 nm) pump beams and a spectrally-broad red (607 nm) beam as the Stokes beam. A spectrometer and a planar Fabry-Perot interferometer used in the imaging mode are used to record the spectrally broad CARS spectra and the spontaneous Rayleigh scattering spectra, respectively. Time-resolved simultaneous measurement of temperature, absolute mole fractions of N2, O2, and H2, and two components of velocity in a Hencken burner flame were performed to demonstrate the technique.

  13. Radar Interferometric Observations of Destabilized Rockglaciers

    NASA Astrophysics Data System (ADS)

    Strozzi, Tazio; Delaloye, Reynald; Raetzo, Hugo; Wegmuller, Urs

    2010-03-01

    Analysis of ERS-1/2 Tandem SAR interferograms for inventorying mass wasting in the periglacial belt of the Valais Alps (Switzerland) has evidenced - what was not expected before - that at least 10 rockglaciers were affected by very rapid movements of about 1 cm/day in 1995-1999. Currently, the detection of the state of activity of these very rapidly moving rockglaciers is hardly feasible with satellite SAR data, because of signal decorrelation after the 35, 46 and 11 days repeat intervals of the ENVISAT, ALOS and TerraSAR-X satellites, respectively. The role of space-borne radar interferometry as an element in a warning system is thus insignificant for these very rapid landslides, but an in- situ radar imaging system can overcome some of the limitations of satellite systems. In this contribution we present results from terrestrial radar interferometric measurements of two destabilized rockglaciers performed in August 2009.

  14. (Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. IV. Physical properties derived from spectral energy distributions

    NASA Astrophysics Data System (ADS)

    Miettinen, O.; Delvecchio, I.; Smolčić, V.; Novak, M.; Aravena, M.; Karim, A.; Murphy, E. J.; Schinnerer, E.; Capak, P.; Ilbert, O.; Intema, H. T.; Laigle, C.; McCracken, H. J.

    2017-01-01

    Context. Submillimetre galaxies (SMGs) in the early Universe are potential antecedents of the most massive galaxies we see in the present-day Universe. An important step towards quantifying this galactic evolutionary connection is to investigate the fundamental physical properties of SMGs, such as their stellar mass content (M⋆) and star formation rate (SFR). Aims: We attempt to characterise the physical nature of a 1.1 mm selected, flux-limited, and interferometrically followed up sample of SMGs in the COSMOS field. Methods: We used the latest release of the MAGPHYS code to fit the multiwavelength (UV to radio) spectral energy distributions (SEDs) of 16 of the target SMGs, which lie at redshifts z ≃ 1.6-5.3. We also constructed the pure radio SEDs of our SMGs using three different radio bands (325 MHz, 1.4 GHz, and 3 GHz). Moreover, since two SMGs in our sample, AzTEC 1 and AzTEC 3, benefit from previous 12C16O line observations, we studied their properties in more detail. Results: The median and 16th-84th percentile ranges of M⋆, infrared (8-1000 μm) luminosity (LIR), SFR, dust temperature (Tdust), and dust mass (Mdust) were derived to be log (M⋆/M⊙) = 10.96+ 0.34-0.19, log (LIR/L⊙) = 12.93+ 0.09-0.19, SFR = 856+ 191-310M⊙ yr-1, Tdust = 40.6+ 7.5-8.1 K, and log (Mdust/M⊙) = 9.17+ 0.03-0.33, respectively. We found that 63% of our target SMGs lie above the galaxy main sequence by more than a factor of 3 and, hence, are starbursts. The 3 GHz radio sizes we have previously measured for the target SMGs were compared with the present M⋆ estimates, and we found that the z> 3 SMGs are fairly consistent with the mass-size relationship of z 2 compact, quiescent galaxies (cQGs). The median radio spectral index is found to be α = -0.77+ 0.28-0.42. The median IR-radio correlation parameter is found to be q = 2.27+ 0.27-0.13, which is lower than was measured locally (median q = 2.64). The gas-to-dust mass ratio for AzTEC 1 is derived to be δgdr = 90+ 23

  15. Interferometric field of view measurements at the VLTI

    NASA Astrophysics Data System (ADS)

    Hummel, Christian A.; Le Bouquin, Jean-Baptiste; Merand, Antoine

    2016-07-01

    In August 2014 we performed technical observations at the VLTI with the AMBER and PIONIER beam combiners to measure the interferometric field of view (FOV). As targets we included binaries with component separations between 100 and 300 mas, for which orbits and/or interferometric speckle measurements are available from the Washington Double Star databases or from the literature. The analysis included effects such as bandwidth and time smearing of the interferograms, and photometric attenuation due to the seeing and image quality based on a new formalism of the ESO Exposure Time Calculators. We also consulted the literature for results of interferometric surveys such as the SMASH survey.1 to estimate the effective FOV for these instruments. Based on our analysis, we conclude that emission outside a FOV diameter of 160 mas will be significantly suppressed if not completely invisible. These results provide important information as to the size of the source structure to be included when modeling interferometric data obtained with these instruments.

  16. Interferometric optical tweezers

    NASA Astrophysics Data System (ADS)

    Chiou, Arthur E.; Wang, Wen; Sonek, Greg J.; Hong, John; Berns, M. W.

    1997-02-01

    We report the first experimental demonstration of an optical trap that uses interference fringes for the trapping and micro-manipulation of microscopic objects. The finges can be generated either by two-beam interference or by projecting a reduced image of a Ronchi ruling on the sample plane. Polystyrene beads of a few microns in diameter can be trapped and held in a bright region of a set of interference fringes and subsequently moved to a designated position by sweeping the fringes across the field of view. The potential advantages of extending this technique to the trapping of rod-shaped samples and for independent micro-manipulation of two or more particles are discussed.

  17. Spectral modulation interferometry for quantitative phase imaging

    PubMed Central

    Shang, Ruibo; Chen, Shichao; Li, Chengshuai; Zhu, Yizheng

    2015-01-01

    We propose a spectral-domain interferometric technique, termed spectral modulation interferometry (SMI), and present its application to high-sensitivity, high-speed, and speckle-free quantitative phase imaging. In SMI, one-dimensional complex field of an object is interferometrically modulated onto a broadband spectrum. Full-field phase and intensity images are obtained by scanning along the orthogonal direction. SMI integrates the high sensitivity of spectral-domain interferometry with the high speed of spectral modulation to quantify fast phase dynamics, and its dispersive and confocal nature eliminates laser speckles. The principle and implementation of SMI are discussed. Its performance is evaluated using static and dynamic objects. PMID:25780737

  18. Application Of Mathematical Morphology To FLIR Images

    NASA Astrophysics Data System (ADS)

    Richardson, Craig H.; Schafer, Ronald W.

    1987-10-01

    This paper presents an application of morphological systems to the problem of locating man-made objects in Forward Looking Infra Red I FUR) images. The FUR images, consist of compact light concentrated heat) regions corresponding to the object with a darker (cooler) background with some light distractions such as trees, or a forest. The images generally have poor contrast because of the nature of heat sensitive imagery. The goal of this research is to isolate the object (when present) from its background and to provide its exact loca tion within the imaging window. The research focuses upon the selection of the morphological operations, the choice of the shape and size of the structuring elements and the sequence in which the operations are applied. Preliminary experimental results indicate that morphological transformations may be well suited for this application. The compact light areas representing man-made objects are readily separated from the larger light ridges representing trees, or forests.

  19. Pharmaceutical applications of non-linear imaging.

    PubMed

    Strachan, Clare J; Windbergs, Maike; Offerhaus, Herman L

    2011-09-30

    Non-linear optics encompasses a range of optical phenomena, including two- and three-photon fluorescence, second harmonic generation (SHG), sum frequency generation (SFG), difference frequency generation (DFG), third harmonic generation (THG), coherent anti-Stokes Raman scattering (CARS), and stimulated Raman scattering (SRS). The combined advantages of using these phenomena for imaging complex pharmaceutical systems include chemical and structural specificities, high optical spatial and temporal resolutions, no requirement for labels, and the ability to image in an aqueous environment. These features make such imaging well suited for a wide range of pharmaceutical and biopharmaceutical investigations, including material and dosage form characterisation, dosage form digestion and drug release, and drug and nanoparticle distribution in tissues and within live cells. In this review, non-linear optical phenomena used in imaging will be introduced, together with their advantages and disadvantages in the pharmaceutical context. Research on pharmaceutical and biopharmaceutical applications is discussed, and potential future applications of the technology are considered.

  20. Laser interferometric investigations of pulsatile choroidal blood flow: review and new results on the validity of the technique

    NASA Astrophysics Data System (ADS)

    Schmetterer, Leopold F.; Wolzt, M.

    1998-07-01

    A short overview of currently available ocular blood flow techniques is given. We have recently introduced a laser interferometric technique for the measurement of ocular fundus pulsation. The eye is illuminated by a single mode laser beam which is reflected at the anterior corneal surface and the fundus. The two re-emitted waves produce interference fringes from which distance changes between cornea and retina during the cardiac cycle can be calculated. These rhythmic changes in corneo-retinal distance are caused by the arterial pulsatile inflow of blood, which increases the ocular volume. The fundus pulsation amplitude (FPA) is the maximum distance change between cornea and retina during the cardiac cycle and is taken as a relative measure of pulsatile choroidal blood flow. The high reproducibility and the high sensitivity of the method are discussed. In addition, the present article reviews comparative measurement with other techniques for the assessment of choroidal blood flow, which validates the method. Furthermore, we present new data on a comparison of color Doppler imaging in the posterior ciliary arteries and laser interferometric measurement of FPA. Applications of laser interferometric measurement of FPA to study the physiology, the pharmacology, and the pathophysiology of the choroidal circulation are reviewed. In conclusion, FPA can be taken as a relative measure of pulsatile choroidal blood flow. The technique is particularly suitable for pharmacodynamic studies.

  1. Raman chemical imaging: Development and applications

    NASA Astrophysics Data System (ADS)

    Schaeberle, Michael D.

    Recent advances in electronically tunable filters, such as acousto-optic tunable filters (AOTF) and liquid crystal tunable filters (LCTF), combined with multispectral image processing strategies make Raman chemical imaging a powerful technique for the routine analysis of material chemical architecture. Raman chemical imaging combines Raman spectroscopy and digital imaging technology to assess material molecular composition and structure. Raman spectroscopy probes molecular composition and structure without being destructive to the sample. The spectrum for an analyte within even a complex host matrix is harnessed to generate unique contrast intrinsic to the analyte species without the use of stains, dyes, or contrast agents. This thesis provides a brief introduction to the field of Raman chemical imaging by describing the major methods employed. The research presented here focuses on wide field Raman imaging in conjunction with electronically tunable filters, and therefore a general methodology for performing Raman chemical imaging analysis of unknown samples is described. The AOTF and LCTF Raman chemical imaging microscopes developed during this research are also presented. The general operating principles of the AOTF and the LCTF are briefly discussed along with their specific implementation within the microscope based imaging systems. Raman chemical imaging represents an efficient, widely applicable approach for understanding the relationship between material molecular architecture and material function, which is central to the engineering of advanced materials. AOTF Raman chemical imaging has been employed in the visualization of the architecture of polypropylene and polyurethane blended polymers. High fidelity Raman images were and domains in the 3-5 mum ranges were differentiated. The AOTF Raman chemical imaging microscope has also been applied to the histopathological characterization of human breast tissue. A foreign polymer inclusion in the tissue was

  2. ICG fluorescence imaging and its medical applications

    NASA Astrophysics Data System (ADS)

    Miwa, Mitsuharu; Shikayama, Takahiro

    2008-12-01

    This paper presents a novel optical angiography system, and introduces its medical applications. We developed the optical enhanced imaging system which can observe the blood and lymphatic vessels as the Indocyanine green (ICG) fluorescence image. The imaging system consists of 760nm light emitted diode (LED) as excite light, CCD camera as a detector, a high-pass optical filter in front of the CCD and video processing system. The advantage of ICG fluorescence method is safe (radiation free), high sensitive, real time monitoring of blood and/or lymphatic flow, small size, easy to operate and cost effective compared to conventional X-ray angiography or scintigraphy. We have applied this method to several clinical applications such as breast cancer sentinel lymph node (SLN) navigation, lymph edema diagnostic and identification of liver segmentation. In each application, ICG fluorescence method shows useful result. It's indicated that this method is promising technique as optical angiography.

  3. rtpipe: Searching for Fast Radio Transients in Interferometric Data

    NASA Astrophysics Data System (ADS)

    Law, Casey J.

    2017-06-01

    rtpipe (real-time pipeline) analyzes radio interferometric data with an emphasis on searching for transient or variable astrophysical sources. The package combines single-dish concepts such as dedispersion and filters with interferometric concepts, including images and the uv-plane. In contrast to time-domain data recorded with large single-dish telescopes, visibilities from interferometers can precisely localize sources anywhere in the entire field of view. rtpipe opens interferometers to the study of fast transient sky, including sources like pulsars, stellar flares, rotating radio transients, and fast radio bursts. Key portions of the search pipeline, such as image generation and dedispersion, have been accelerated. That, in combination with its multi-threaded, multi-node design, makes rtpipe capable of searching millisecond timescale data in real time on small compute clusters.

  4. Application of numerical methods to elasticity imaging.

    PubMed

    Castaneda, Benjamin; Ormachea, Juvenal; Rodríguez, Paul; Parker, Kevin J

    2013-03-01

    Elasticity imaging can be understood as the intersection of the study of biomechanical properties, imaging sciences, and physics. It was mainly motivated by the fact that pathological tissue presents an increased stiffness when compared to surrounding normal tissue. In the last two decades, research on elasticity imaging has been an international and interdisciplinary pursuit aiming to map the viscoelastic properties of tissue in order to provide clinically useful information. As a result, several modalities of elasticity imaging, mostly based on ultrasound but also on magnetic resonance imaging and optical coherence tomography, have been proposed and applied to a number of clinical applications: cancer diagnosis (prostate, breast, liver), hepatic cirrhosis, renal disease, thyroiditis, arterial plaque evaluation, wall stiffness in arteries, evaluation of thrombosis in veins, and many others. In this context, numerical methods are applied to solve forward and inverse problems implicit in the algorithms in order to estimate viscoelastic linear and nonlinear parameters, especially for quantitative elasticity imaging modalities. In this work, an introduction to elasticity imaging modalities is presented. The working principle of qualitative modalities (sonoelasticity, strain elastography, acoustic radiation force impulse) and quantitative modalities (Crawling Waves Sonoelastography, Spatially Modulated Ultrasound Radiation Force (SMURF), Supersonic Imaging) will be explained. Subsequently, the areas in which numerical methods can be applied to elasticity imaging are highlighted and discussed. Finally, we present a detailed example of applying total variation and AM-FM techniques to the estimation of elasticity.

  5. Single-exposure super-resolved interferometric microscopy by RGB multiplexing in lensless configuration

    NASA Astrophysics Data System (ADS)

    Granero, Luis; Ferreira, Carlos; Zalevsky, Zeev; García, Javier; Micó, Vicente

    2016-07-01

    Single-Exposure Super-Resolved Interferometric Microscopy (SESRIM) reports on a way to achieve one-dimensional (1-D) superresolved imaging in digital holographic microscopy (DHM) by a single illumination shot and digital recording. SESRIM provides color-coded angular multiplexing of the accessible sample's range of spatial frequencies and it allows their recording in a single CCD (color or monochrome) snapshot by adding 3 RGB coherent reference beams at the output plane. In this manuscript, we extend the applicability of SESRIM to the field of digital in-line holographic microscopy (DIHM), that is, working without lenses. As consequence of the in-line configuration, an additional restriction concerning the object field of view (FOV) must be imposed to the technique. Experimental results are reported for both a synthetic object (USAF resolution test target) and a biological sample (swine sperm sample) validating this new kind of superresolution imaging method named as lensless SESRIM (L-SESRIM).

  6. Scattered Radiation Emission Imaging: Principles and Applications

    PubMed Central

    Nguyen, M. K.; Truong, T. T.; Morvidone, M.; Zaidi, H.

    2011-01-01

    Imaging processes built on the Compton scattering effect have been under continuing investigation since it was first suggested in the 50s. However, despite many innovative contributions, there are still formidable theoretical and technical challenges to overcome. In this paper, we review the state-of-the-art principles of the so-called scattered radiation emission imaging. Basically, it consists of using the cleverly collected scattered radiation from a radiating object to reconstruct its inner structure. Image formation is based on the mathematical concept of compounded conical projection. It entails a Radon transform defined on circular cone surfaces in order to express the scattered radiation flux density on a detecting pixel. We discuss in particular invertible cases of such conical Radon transforms which form a mathematical basis for image reconstruction methods. Numerical simulations performed in two and three space dimensions speak in favor of the viability of this imaging principle and its potential applications in various fields. PMID:21747823

  7. Reflectometric measurement of plasma imaging and applications

    NASA Astrophysics Data System (ADS)

    Mase, A.; Ito, N.; Oda, M.; Komada, Y.; Nagae, D.; Zhang, D.; Kogi, Y.; Tobimatsu, S.; Maruyama, T.; Shimazu, H.; Sakata, E.; Sakai, F.; Kuwahara, D.; Yoshinaga, T.; Tokuzawa, T.; Nagayama, Y.; Kawahata, K.; Yamaguchi, S.; Tsuji-Iio, S.; Domier, C. W.; Luhmann, N. C., Jr.; Park, H. K.; Yun, G.; Lee, W.; Padhi, S.; Kim, K. W.

    2012-01-01

    Progress in microwave and millimeter-wave technologies has made possible advanced diagnostics for application to various fields, such as, plasma diagnostics, radio astronomy, alien substance detection, airborne and spaceborne imaging radars called as synthetic aperture radars, living body measurements. Transmission, reflection, scattering, and radiation processes of electromagnetic waves are utilized as diagnostic tools. In this report we focus on the reflectometric measurements and applications to biological signals (vital signal detection and breast cancer detection) as well as plasma diagnostics, specifically by use of imaging technique and ultra-wideband radar technique.

  8. Spaceborne imaging radar - Geologic and oceanographic applications

    NASA Technical Reports Server (NTRS)

    Elachi, C.

    1980-01-01

    Synoptic, large-area radar images of the earth's land and ocean surface, obtained from the Seasat orbiting spacecraft, show the potential for geologic mapping and for monitoring of ocean surface patterns. Structural and topographic features such as lineaments, anticlines, folds and domes, drainage patterns, stratification, and roughness units can be mapped. Ocean surface waves, internal waves, current boundaries, and large-scale eddies have been observed in numerous images taken by the Seasat imaging radar. This article gives an illustrated overview of these applications.

  9. UVMULTIFIT: A versatile tool for fitting astronomical radio interferometric data

    NASA Astrophysics Data System (ADS)

    Martí-Vidal, I.; Vlemmings, W. H. T.; Muller, S.; Casey, S.

    2014-03-01

    Context. The analysis of astronomical interferometric data is often performed on the images obtained after deconvolving the interferometer's point spread function. This strategy can be understood (especially for cases of sparse arrays) as fitting models to models, since the deconvolved images are already non-unique model representations of the actual data (i.e., the visibilities). Indeed, the interferometric images may be affected by visibility gridding, weighting schemes (e.g., natural vs. uniform), and the particulars of the (non-linear) deconvolution algorithms. Fitting models to the direct interferometric observables (i.e., the visibilities) is preferable in the cases of simple (analytical) sky intensity distributions. Aims: We present UVMULTIFIT, a versatile library for fitting visibility data, implemented in a Python-based framework. Our software is currently based on the CASA package, but can be easily adapted to other analysis packages, provided they have a Python API. Methods: The user can simultaneously fit an indefinite number of source components to the data, each of which depend on any algebraic combination of fitting parameters. Fits to individual spectral-line channels or simultaneous fits to all frequency channels are allowed. Results: We have tested the software with synthetic data and with real observations. In some cases (e.g., sources with sizes smaller than the diffraction limit of the interferometer), the results from the fit to the visibilities (e.g., spectra of close by sources) are far superior to the output obtained from the mere analysis of the deconvolved images. Conclusions: UVMULTIFIT is a powerful improvement of existing tasks to extract the maximum amount of information from visibility data, especially in cases close to the sensitivity/resolution limits of interferometric observations.

  10. Microstructured optical fiber interferometric breathing sensor

    NASA Astrophysics Data System (ADS)

    Favero, Fernando C.; Villatoro, Joel; Pruneri, Valerio

    2012-03-01

    In this paper a simple photonic crystal fiber (PCF) interferometric breathing sensor is introduced. The interferometer consists of a section of PCF fusion spliced at the distal end of a standard telecommunications optical fiber. Two collapsed regions in the PCF caused by the splicing process allow the excitation and recombination of a core and a cladding PCF mode. As a result, the reflection spectrum of the device exhibits a sinusoidal interference pattern that instantly shifts when water molecules, present in exhaled air, are adsorbed on or desorbed from the PCF surface. The device can be used to monitor a person's breathing whatever the respiration rate. The device here proposed could be particularly important in applications where electronic sensors fail or are not recommended. It may also be useful in the evaluation of a person's health and even in the diagnosis and study of the progression of serious illnesses such as sleep apnea syndrome.

  11. Application of image guidance in pituitary surgery

    PubMed Central

    de Lara, Danielle; Filho, Leo F. S. Ditzel; Prevedello, Daniel M.; Otto, Bradley A.; Carrau, Ricardo L.

    2012-01-01

    Background: Surgical treatment of pituitary pathologies has evolved along the years, adding safety and decreasing morbidity related to the procedure. Advances in the field of radiology, coupled with stereotactic technology and computer modeling, have culminated in the contemporary and widespread use of image guidance systems, as we know them today. Image guidance navigation has become a frequently used technology that provides continuous three-dimensional information for the accurate performance of neurosurgical procedures. We present a discussion about the application of image guidance in pituitary surgeries. Methods: Major indications for image guidance neuronavigation application in pituitary surgery are presented and demonstrated with illustrative cases. Limitations of this technology are also presented. Results: Patients presenting a history of previous transsphenoidal surgeries, anatomical variances of the sphenoid sinus, tumors with a close relation to the internal carotid arteries, and extrasellar tumors are the most important indications for image guidance in pituitary surgeries. The high cost of the equipment, increased time of surgery due to setup time, and registration and the need of specific training for the operating room personnel could be pointed as limitations of this technology. Conclusion: Intraoperative image guidance systems provide real-time images, increasing surgical accuracy and enabling safe, minimally invasive interventions. However, the use of intraoperative navigation is not a replacement for surgical experience and a systematic knowledge of regional anatomy. It must be recognized as a tool by which the neurosurgeon can reduce the risk associated with surgical approach and treatment of pituitary pathologies. PMID:22826819

  12. Characterizing Levees using Polarimetric and Interferometric Synthetic Aperture Radar Imagery

    NASA Astrophysics Data System (ADS)

    Dabbiru, L.; Aanstoos, J. V.; Mahrooghy, M.; Gokaraju, B.; Nobrega, R. A.; Younan, N. H.

    2011-12-01

    Monitoring the physical condition of levees is vital in order to protect them from flooding. The dynamics of subsurface water events can cause damage on levee structures which could lead to slough slides, sand boils or through seepage. Synthetic Aperture Radar (SAR) technology, due to its high spatial resolution and soil penetration capability, is a good choice to identify such problem areas so that they can be treated to avoid possible catastrophic failure. The radar polarimetric and interferometric data is capable of identifying variations in soil properties of the areas which might cause levee failure. The study area encompasses portion of levees of the lower Mississippi river in the United States. The methodology of this research is mainly categorized into two streams: 1) polarimetric data analysis and classification, and 2) interferometric analysis. Two sources of SAR imagery are used: a) quad-polarized, L-band data from Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) for polarimetric classification, and b) high resolution dual-polarized Terrasar-X data for interferometric analysis. NASA's UAVSAR imagery acquired between 2009 and 2011 are used for the analysis. The polarimetric classification is performed based on the decomposition parameters: entropy (H), anisotropy (A) and alpha (α) and the results detected slough slides on the levees and potential future slides. In the interferometric approach, the Terrasar-X SAR images acquired at different times in the year 2011 are combined into pairs to exploit the phase difference of the signals. The interferometric information is used to find evidence of potential small-scale deformations which could be pre-cursors to levee failure.

  13. Reconsidering the advantages of the three-dimensional representation of the interferometric transform for imaging with non-coplanar baselines and wide fields of view

    NASA Astrophysics Data System (ADS)

    Smith, D. M. P.; Young, A.; Davidson, D. B.

    2017-07-01

    Radio telescopes with baselines that span thousands of kilometres and with fields of view that span tens of degrees have been recently deployed, such as the Low Frequency Array, and are currently being developed, such as the Square Kilometre Array. Additionally, there are proposals for space-based instruments with all-sky imaging capabilities, such as the Orbiting Low Frequency Array. Such telescopes produce observations with three-dimensional visibility distributions and curved image domains. In most work to date, the visibility distribution has been converted to a planar form to compute the brightness map using a two-dimensional Fourier transform. The celestial sphere is faceted in order to counter pixel distortion at wide angles, with each such facet requiring a unique planar form of the visibility distribution. Under the above conditions, the computational and storage complexities of this approach can become excessive. On the other hand, when using the direct Fourier transform approach, which maintains the three-dimensional shapes of the visibility distribution and celestial sphere, the non-coplanar visibility component requires no special attention. Furthermore, as the celestial samples are placed directly on the curved surface of the celestial sphere, pixel distortion at wide angles is avoided. In this paper, a number of examples illustrate that under these conditions (very long baselines and very wide fields of view) the costs of the direct Fourier transform may be comparable to (or even lower than) methods that utilise the two-dimensional fast Fourier transform.

  14. Imaging In focus: Reflected light imaging: Techniques and applications.

    PubMed

    Guggenheim, Emily J; Lynch, Iseult; Rappoport, Joshua Z

    2017-02-01

    Reflectance imaging is a broad term that describes the formation of images by the detection of illumination light that is back-scattered from reflective features within a sample. Reflectance imaging can be performed in a variety of different configurations, such as confocal, oblique angle illumination, structured illumination, interferometry and total internal reflectance, permitting a plethora of biomedical applications. Reflectance imaging has proven indispensable for critical investigations into the safety and understanding of biomedically and environmentally relevant nano-materials, an area of high priority and investment. The non-destructive in vivo imaging ability of reflectance techniques permits alternative diagnostic strategies that may eventually facilitate the eradication of some invasive biopsy procedures. Reflectance can also provide additional structural information and clarity necessary in fluorescent based in vivo studies. Near-coverslip interrogation techniques, such as reflectance interferometry and total internal reflection, have provided a label free means to investigate cell-surface contacts, cell motility and vesicle trafficking in vivo and in vitro. Other key advances include the ability to acquire superresolution reflectance images providing increased spatial resolution.

  15. Imaging systems and applications: introduction to the feature.

    PubMed

    Imai, Francisco H; Linne von Berg, Dale C; Skauli, Torbjørn; Tominaga, Shoji; Zalevsky, Zeev

    2014-05-01

    Imaging systems have numerous applications in industrial, military, consumer, and medical settings. Assembling a complete imaging system requires the integration of optics, sensing, image processing, and display rendering. This issue features original research ranging from design of stimuli for human perception, optics applications, and image enhancement to novel imaging modalities in both color and infrared spectral imaging, gigapixel imaging as well as a systems perspective to imaging.

  16. Passive millimeter-wave camera with interferometric processing

    NASA Astrophysics Data System (ADS)

    Nohmi, Hitoshi; Ohnishi, Seiki; Kujubu, Osamu

    2007-04-01

    A proto-type passive millimeter-wave (MMW) camera with interferometric processing has been developed and evaluated to confirm the feasibility of the interferometric MMW camera and to study the characteristics of MMW images. This proto-type camera is comprised of the minimum configuration as an interferometric imager which consists of two sets of a W-band receiver with a horn antenna, and a digital processing unit. The position of these two antennas with W-band front-end moves on the precision linear slider in horizontal and vertical axis. The coherently amplified two channel signals are digitized and processed in the hardware processor. The process is comprised of correlation of all combination of each axis data, and integration to improve the signal to noise ratio. The integrated data is processed to make an image by matched filter processing. The integration time is from 1mS to 10S depending on required integration gain. The maximum synthesized antenna aperture size is 1m for horizontal axis and 50cm for vertical axis. In this paper, the evaluation of the proto-type P-MMW camera is descried. After the evaluation, some improvement was scheduled and conducted. Also, future plan for a real-time camera using this technique is presented .

  17. The application of interferometry to optical astronomical imaging.

    PubMed

    Baldwin, John E; Haniff, Christopher A

    2002-05-15

    In the first part of this review we survey the role optical/infrared interferometry now plays in ground-based astronomy. We discuss in turn the origins of astronomical interferometry, the motivation for its development, the techniques of its implementation, examples of its astronomical significance, and the limitations of the current generation of interferometric arrays. The second part focuses on the prospects for ground-based astronomical imaging interferometry over the near to mid-term (i.e. 10 years) at optical and near-infrared wavelengths. An assessment is made of the astronomical and technical factors which determine the optimal designs for imaging arrays. An analysis based on scientific capability, technical feasibility and cost argues for an array of large numbers of moderate-sized (2 m class) telescopes rather than one comprising a small number of much larger collectors.

  18. Spatially multiplexed interferometric microscopy with partially coherent illumination

    NASA Astrophysics Data System (ADS)

    Picazo-Bueno, José Ángel; Zalevsky, Zeev; García, Javier; Ferreira, Carlos; Micó, Vicente

    2016-10-01

    We have recently reported on a simple, low cost, and highly stable way to convert a standard microscope into a holographic one [Opt. Express 22, 14929 (2014)]. The method, named spatially multiplexed interferometric microscopy (SMIM), proposes an off-axis holographic architecture implemented onto a regular (nonholographic) microscope with minimum modifications: the use of coherent illumination and a properly placed and selected one-dimensional diffraction grating. In this contribution, we report on the implementation of partially (temporally reduced) coherent illumination in SMIM as a way to improve quantitative phase imaging. The use of low coherence sources forces the application of phase shifting algorithm instead of off-axis holographic recording to recover the sample's phase information but improves phase reconstruction due to coherence noise reduction. In addition, a less restrictive field of view limitation (1/2) is implemented in comparison with our previously reported scheme (1/3). The proposed modification is experimentally validated in a regular Olympus BX-60 upright microscope considering a wide range of samples (resolution test, microbeads, swine sperm cells, red blood cells, and prostate cancer cells).

  19. Full surface interferometric testing of grazing incidence mirrors

    NASA Astrophysics Data System (ADS)

    Remo, John L.

    1990-02-01

    This contract demonstrated the proof-of-principle of the Full Surface Interferometric Scanner (FSIS), an instrument which can rapidly and reliably measure both the full surface figure as well as the macroroughness of grazing incidence optics. The FSIS has the potential to fill the need of SDIO to characterize and qualify the necessary off-axis aspherical mirror technology that will be used for weapon pointing, beam control, and beam propagation through several environments and countermeasures. This instrument design is based on the use of normal incidence, sub-aperture interferometry and wavefront shearing interferometry which surmounts many of the problems encountered by other (e.g., long trace profilers) techniques. This new system, the FSIS, for which we have developed a breadboard system which makes novel use of three sequential operations: sub-aperture slope measurement, wavefront integration, and surface profile synthesis. It appears that the FSIS will find application in X ray and UV high resolution lithography, medical imaging, astronomy, physics, microbiology, and industrial (surface) quality control.

  20. Digital imaging applications in anatomic pathology.

    PubMed

    Leong, F Joel W-M; Leong, Anthony S-Y

    2003-03-01

    Digital imaging has progressed at a rapid rate and is likely to eventually replace chemical photography in most areas of professional and amateur digital image acquisition. In pathology, digital microscopy has implications beyond that of taking a photograph. The arguments for adopting this new medium are compelling, and given similar developments in other areas of pathology and radiologic imaging, acceptance of the digital medium should be viewed as a component of the technological evolution of the laboratory. A digital image may be stored, replicated, catalogued, employed for educational purposes, transmitted for further interpretation (telepathology), analyzed for salient features (medical vision/image analysis), or form part of a wider digital healthcare strategy. Despite advances in digital camera technology, good image acquisition still requires good microscope optics and the correct calibration of all system components, something which many neglect. The future of digital imaging in pathology is very promising and new applications in the fields of automated quantification and interpretation are likely to have profound long-term influence on the practice of anatomic pathology. This paper discusses the state of the art of digital imaging in anatomic pathology.

  1. Interferometric optical vortex array generator

    SciTech Connect

    Vyas, Sunil; Senthilkumaran, P

    2007-05-20

    Two new interferometric configurations for optical vortex array generation are presented.These interferometers are different from the conventional interferometers in that they are capable of producing a large number of isolated zeros of intensity, and all of them contain optical vortices. Simulation and theory for optical vortex array generation using three-plane-wave interference is presented. The vortex dipole array produced this way is noninteracting, as there are no attraction or repulsion forces between them, leading to annihilation or creation of vortex pairs.

  2. Interferometric optical vortex array generator.

    PubMed

    Vyas, Sunil; Senthilkumaran, P

    2007-05-20

    Two new interferometric configurations for optical vortex array generation are presented. These interferometers are different from the conventional interferometers in that they are capable of producing a large number of isolated zeros of intensity, and all of them contain optical vortices. Simulation and theory for optical vortex array generation using three-plane-wave interference is presented. The vortex dipole array produced this way is noninteracting, as there are no attraction or repulsion forces between them, leading to annihilation or creation of vortex pairs.

  3. Fundus autofluorescence applications in retinal imaging.

    PubMed

    Gabai, Andrea; Veritti, Daniele; Lanzetta, Paolo

    2015-05-01

    Fundus autofluorescence (FAF) is a relatively new imaging technique that can be used to study retinal diseases. It provides information on retinal metabolism and health. Several different pathologies can be detected. Peculiar AF alterations can help the clinician to monitor disease progression and to better understand its pathogenesis. In the present article, we review FAF principles and clinical applications.

  4. Fundus autofluorescence applications in retinal imaging

    PubMed Central

    Gabai, Andrea; Veritti, Daniele; Lanzetta, Paolo

    2015-01-01

    Fundus autofluorescence (FAF) is a relatively new imaging technique that can be used to study retinal diseases. It provides information on retinal metabolism and health. Several different pathologies can be detected. Peculiar AF alterations can help the clinician to monitor disease progression and to better understand its pathogenesis. In the present article, we review FAF principles and clinical applications. PMID:26139802

  5. Recent applications of hyperspectral imaging in microbiology.

    PubMed

    Gowen, Aoife A; Feng, Yaoze; Gaston, Edurne; Valdramidis, Vasilis

    2015-05-01

    Hyperspectral chemical imaging (HSI) is a broad term encompassing spatially resolved spectral data obtained through a variety of modalities (e.g. Raman scattering, Fourier transform infrared microscopy, fluorescence and near-infrared chemical imaging). It goes beyond the capabilities of conventional imaging and spectroscopy by obtaining spatially resolved spectra from objects at spatial resolutions varying from the level of single cells up to macroscopic objects (e.g. foods). In tandem with recent developments in instrumentation and sampling protocols, applications of HSI in microbiology have increased rapidly. This article gives a brief overview of the fundamentals of HSI and a comprehensive review of applications of HSI in microbiology over the past 10 years. Technical challenges and future perspectives for these techniques are also discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Interferometric phase reconstruction using simplified coherence network

    NASA Astrophysics Data System (ADS)

    Zhang, Kui; Song, Ruiqing; Wang, Hui; Wu, Di; Wang, Hua

    2016-09-01

    Interferometric time-series analysis techniques, which extend the traditional differential radar interferometry, have demonstrated a strong capability for monitoring ground surface displacement. Such techniques are able to obtain the temporal evolution of ground deformation within millimeter accuracy by using a stack of synthetic aperture radar (SAR) images. In order to minimize decorrelation between stacked SAR images, the phase reconstruction technique has been developed recently. The main idea of this technique is to reform phase observations along a SAR stack by taking advantage of a maximum likelihood estimator which is defined on the coherence matrix estimated from each target. However, the phase value of a coherence matrix element might be considerably biased when its corresponding coherence is low. In this case, it will turn to an outlying sample affecting the corresponding phase reconstruction process. In order to avoid this problem, a new approach is developed in this paper. This approach considers a coherence matrix element to be an arc in a network. A so-called simplified coherence network (SCN) is constructed to decrease the negative impact of outlying samples. Moreover, a pointed iterative strategy is designed to resolve the transformed phase reconstruction problem defined on a SCN. For validation purposes, the proposed method is applied to 29 real SAR images. The results demonstrate that the proposed method has an excellent computational efficiency and could obtain more reliable phase reconstruction solutions compared to the traditional method using phase triangulation algorithm.

  7. Optical fiber interferometric sensors for chemical detection

    SciTech Connect

    Butler, M.A.

    1990-01-01

    Interferometric sensors take advantage of a unique property of light, its macroscopic coherence, which has resulted in extremely sensitive devices for the detection of physical parameters. In this paper I will discuss three new chemical detection mechanisms which utilize optical interferometric techniques. 15 refs., 11 figs.

  8. Acoustic Location of Lightning Using Interferometric Techniques

    NASA Astrophysics Data System (ADS)

    Erives, H.; Arechiga, R. O.; Stock, M.; Lapierre, J. L.; Edens, H. E.; Stringer, A.; Rison, W.; Thomas, R. J.

    2013-12-01

    Acoustic arrays have been used to accurately locate thunder sources in lightning flashes. The acoustic arrays located around the Magdalena mountains of central New Mexico produce locations which compare quite well with source locations provided by the New Mexico Tech Lightning Mapping Array. These arrays utilize 3 outer microphones surrounding a 4th microphone located at the center, The location is computed by band-passing the signal to remove noise, and then computing the cross correlating the outer 3 microphones with respect the center reference microphone. While this method works very well, it works best on signals with high signal to noise ratios; weaker signals are not as well located. Therefore, methods are being explored to improve the location accuracy and detection efficiency of the acoustic location systems. The signal received by acoustic arrays is strikingly similar to th signal received by radio frequency interferometers. Both acoustic location systems and radio frequency interferometers make coherent measurements of a signal arriving at a number of closely spaced antennas. And both acoustic and interferometric systems then correlate these signals between pairs of receivers to determine the direction to the source of the received signal. The primary difference between the two systems is the velocity of propagation of the emission, which is much slower for sound. Therefore, the same frequency based techniques that have been used quite successfully with radio interferometers should be applicable to acoustic based measurements as well. The results presented here are comparisons between the location results obtained with current cross correlation method and techniques developed for radio frequency interferometers applied to acoustic signals. The data were obtained during the summer 2013 storm season using multiple arrays sensitive to both infrasonic frequency and audio frequency acoustic emissions from lightning. Preliminary results show that

  9. General adaptive-neighborhood technique for improving synthetic aperture radar interferometric coherence estimation.

    PubMed

    Vasile, Gabriel; Trouvé, Emmanuel; Ciuc, Mihai; Buzuloiu, Vasile

    2004-08-01

    A new method for filtering the coherence map issued from synthetic aperture radar (SAR) interferometric data is presented. For each pixel of the interferogram, an adaptive neighborhood is determined by a region-growing technique driven by the information provided by the amplitude images. Then pixels in the derived adaptive neighborhood are complex averaged to yield the filtered value of the coherence, after a phase-compensation step is performed. An extension of the algorithm is proposed for polarimetric interferometric SAR images. The proposed method has been applied to both European Remote Sensing (ERS) satellite SAR images and airborne high-resolution polarimetric interferometric SAR images. Both subjective and objective performance analysis, including coherence edge detection, shows that the proposed method provides better results than the standard phase-compensated fixed multilook filter and the Lee adaptive coherence filter.

  10. Lensless single-exposure super-resolved interferometric microscopy

    NASA Astrophysics Data System (ADS)

    Granero, Luis; Ferreira, Carlos; García, Javier; Micó, Vicente

    2013-04-01

    Single Exposure Super Resolved Interferometric Microscopy (SESRIM) has been recently proposed as a way to achieve one dimensional super resolved imaging in digital holographic microscopy. SESRIM uses Red-Green-Blue (RGB) multiplexing for illuminating the sample having different propagation angles for each one of the three illumination wavelengths and it has been experimentally validated considering color (A. Calabuig, V. Mico, J. Garcia, Z. Zalevsky, and C. Ferreira, "Single-exposure super-resolved interferometric microscopy by red-green-blue multiplexing," Opt. Lett. 36, 885-887, 2011) and monochrome (A. Calabuig, J. Garcia, C. Ferreira, Z. Zalevsky, and V. Mico, "Resolution improvement by single-exposure superresolved interferometric microscopy with a monochrome sensor," J. Opt. Soc. Am. A 28, 2346-2358, 2011) digital sensors for holographic recording. In this contribution, we will first review some of the characteristics of the previously reported SESRIM approaches and second, we will present preliminary results for the extension of SESRIM to the field of lensless holographic microscopy. Experimental results are reported validating this new kind of superresolution imaging method named as lensless SESRIM (L-SESRIM).

  11. Uncooled LWIR imaging: applications and market analysis

    NASA Astrophysics Data System (ADS)

    Takasawa, Satomi

    2015-05-01

    The evolution of infrared (IR) imaging sensor technology for defense market has played an important role in developing commercial market, as dual use of the technology has expanded. In particular, technologies of both reduction in pixel pitch and vacuum package have drastically evolved in the area of uncooled Long-Wave IR (LWIR; 8-14 μm wavelength region) imaging sensor, increasing opportunity to create new applications. From the macroscopic point of view, the uncooled LWIR imaging market is divided into two areas. One is a high-end market where uncooled LWIR imaging sensor with sensitivity as close to that of cooled one as possible is required, while the other is a low-end market which is promoted by miniaturization and reduction in price. Especially, in the latter case, approaches towards consumer market have recently appeared, such as applications of uncooled LWIR imaging sensors to night visions for automobiles and smart phones. The appearance of such a kind of commodity surely changes existing business models. Further technological innovation is necessary for creating consumer market, and there will be a room for other companies treating components and materials such as lens materials and getter materials and so on to enter into the consumer market.

  12. Multidimensional imaging of the thorax: practical applications.

    PubMed

    Ravenel, J G; McAdams, H P; Remy-Jardin, M; Remy, J

    2001-10-01

    Over the past decade, faster CT scan times, thinner collimation, and the development of multirow detectors, coupled with the increasing capability of computers to process large amounts of data in short periods of time, have lead to an expansion in the ability to create diagnostically useful two-dimensional (2D) and three-dimensional (3D) images within the thorax. Applications within the thorax include, but are not limited to, evaluation of pulmonary and systemic vasculature, evaluation of the tracheobronchial tree, and delineation of diffuse lung disease. Pulmonary nodule volume and growth can be more accurately predicted, and represents an improvement in the evaluation of the solitary pulmonary nodule. Multiplanar images increase our understanding of thoracic anatomy and can help to guide bronchoscopic procedures. Because there are strengths and weaknesses to all the reconstruction algorithms, the utility of any given technique is dependent on the clinical question to be answered. For instance, although maximum intensity projection imaging (MIP) is helpful in the evaluation of micronodular lung disease, it is of little value in the diagnosis of aortic dissection. As the ability to generate faster and more precise multidimensional images grow, the demand for such imaging is likely to increase. In this review, the authors discuss the various reconstruction techniques available, followed by a discussion of the clinical applications.

  13. System Engineering the Space Infrared Interferometric Telescope (SPIRIT)

    NASA Technical Reports Server (NTRS)

    Hyde, Tristram T.; Leisawitz, David T.; Rinehart, Stephen

    2007-01-01

    The Space Infrared Interferometric Telescope (SPIRIT) was designed to accomplish three scientific objectives: (1) learn how planetary systems form from protostellar disks and how they acquire their inhomogeneous chemical composition; (2) characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets of different types form; and (3) learn how high-redshift galaxies formed and merged to form the present-day population of galaxies. SPIRIT will accomplish these objectives through infrared observations with a two aperture interferometric instrument. This paper gives an overview of SPIRIT design and operation, and how the three design cycle concept study was completed. The error budget for several key performance values allocates tolerances to all contributing factors, and a performance model of the spacecraft plus instrument system demonstrates meeting those allocations with margin.

  14. Quantitative interferometric microscopy cytometer based on regularized optical flow algorithm

    NASA Astrophysics Data System (ADS)

    Xue, Liang; Vargas, Javier; Wang, Shouyu; Li, Zhenhua; Liu, Fei

    2015-09-01

    Cell detections and analysis are important in various fields, such as medical observations and disease diagnoses. In order to analyze the cell parameters as well as observe the samples directly, in this paper, we present an improved quantitative interferometric microscopy cytometer, which can monitor the quantitative phase distributions of bio-samples and realize cellular parameter statistics. The proposed system is able to recover the phase imaging of biological samples in the expanded field of view via a regularized optical flow demodulation algorithm. This algorithm reconstructs the phase distribution with high accuracy with only two interferograms acquired at different time points simplifying the scanning system. Additionally, the method is totally automatic, and therefore it is convenient for establishing a quantitative phase cytometer. Moreover, the phase retrieval approach is robust against noise and background. Excitingly, red blood cells are readily investigated with the quantitative interferometric microscopy cytometer system.

  15. Technology and application advancements of uncooled imagers

    NASA Astrophysics Data System (ADS)

    Norton, Peter W.; Kohin, Margaret

    2005-05-01

    Having delivered over 30,000 uncooled microbolometer based thermal imaging engines, BAE Systems is the world's leading producer. Advancements in technology include the demonstration of broadband microbolometers on a 46 μm pixel pitch which have excellent sensitivity in the MWIR (NETD ~180 mK, 3-5 μm) and LWIR (NETD ~ 15 mK, 8-12 μm) wavebands. Application advancements include the development of a family of thermal weapons sights for the military which will replace current cooled systems with lighter, lower power systems and the introduction of a new generation of handheld and pole mounted thermal imagers for commercial markets.

  16. Acquisition and applications of 3D images

    NASA Astrophysics Data System (ADS)

    Sterian, Paul; Mocanu, Elena

    2007-08-01

    The moiré fringes method and their analysis up to medical and entertainment applications are discussed in this paper. We describe the procedure of capturing 3D images with an Inspeck Camera that is a real-time 3D shape acquisition system based on structured light techniques. The method is a high-resolution one. After processing the images, using computer, we can use the data for creating laser fashionable objects by engraving them with a Q-switched Nd:YAG. In medical field we mention the plastic surgery and the replacement of X-Ray especially in pediatric use.

  17. Image processing applications for geologic mapping

    SciTech Connect

    Abrams, M.; Blusson, A.; Carrere, V.; Nguyen, T.; Rabu, Y.

    1985-03-01

    The use of satellite data, particularly Landsat images, for geologic mapping provides the geologist with a powerful tool. The digital format of these data permits applications of image processing to extract or enhance information useful for mapping purposes. Examples are presented of lithologic classification using texture measures, automatic lineament detection and structural analysis, and use of registered multisource satellite data. In each case, the additional mapping information provided relative to the particular treatment is evaluated. The goal is to provide the geologist with a range of processing techniques adapted to specific mapping problems.

  18. Enhanced resolution in Sar/ISAR imaging using iterative sidelobe apodization.

    PubMed

    Xu, Xiaojian; Narayanan, Ram M

    2005-04-01

    Resolution enhancement techniques in radar imaging have attracted considerable interest in recent years. In this work, we develop an iterative sidelobe apodization technique and investigate its applications to synthetic aperture radar (SAR) and inverse SAR (ISAR) image processing. A modified noninteger Nyquist spatially variant apodization (SVA) formulation is proposed, which is applicable to direct iterative image sidelobe apodization without using computationally intensive upsampling interpolation. A refined iterative sidelobe apodization procedure is then developed for image-resolution enhancement. Examples using this technique demonstrate enhanced image resolution in various applications, including airborne SAR imaging, image processing for three-dimensional interferometric ISAR imaging, and foliage-penetration ultrawideband SAR image processing.

  19. Extended SWIR imaging sensors for hyperspectral imaging applications

    NASA Astrophysics Data System (ADS)

    Weber, A.; Benecke, M.; Wendler, J.; Sieck, A.; Hübner, D.; Figgemeier, H.; Breiter, R.

    2016-05-01

    AIM has developed SWIR modules including FPAs based on liquid phase epitaxy (LPE) grown MCT usable in a wide range of hyperspectral imaging applications. Silicon read-out integrated circuits (ROIC) provide various integration and readout modes including specific functions for spectral imaging applications. An important advantage of MCT based detectors is the tunable band gap. The spectral sensitivity of MCT detectors can be engineered to cover the extended SWIR spectral region up to 2.5μm without compromising in performance. AIM developed the technology to extend the spectral sensitivity of its SWIR modules also into the VIS. This has been successfully demonstrated for 384x288 and 1024x256 FPAs with 24μm pitch. Results are presented in this paper. The FPAs are integrated into compact dewar cooler configurations using different types of coolers, like rotary coolers, AIM's long life split linear cooler MCC030 or extreme long life SF100 Pulse Tube cooler. The SWIR modules include command and control electronics (CCE) which allow easy interfacing using a digital standard interface. The development status and performance results of AIM's latest MCT SWIR modules suitable for hyperspectral systems and applications will be presented.

  20. Rapid Development of Interferometric Software Using MIRIAD and Python

    NASA Astrophysics Data System (ADS)

    Williams, Peter K. G.; Law, Casey J.; Bower, Geoffrey C.

    2012-06-01

    State-of-the-art radio interferometers are complex systems that unleash torrents of data. If current and planned instruments are to routinely meet their performance goals, standard analysis techniques must be significantly improved, becoming simultaneously more sophisticated, more automatic, and more scalable. While there is no shortage of ideas for next-generation algorithms, there is a shortage of development resources, so it is vital that programming environments for interferometric software allow for rapid, flexible development. We present an open-source software package, miriad-python, that provides access to the MIRIAD interferometric reduction system in the Python programming language. The modular design of MIRIAD and the high productivity and accessibility of Python provide an excellent foundation for rapid development of interferometric software. Several other projects with similar goals exist, and we describe them and compare miriad-python with them in detail. Along with an overview of the package design, we present sample code and applications, including the detection of millisecond astrophysical transients, determination and application of nonstandard calibration parameters, interactive data visualization, and a reduction pipeline using a directed acyclic graph dependency model analogous to that of the traditional UNIX tool make. The key aspects of the miriad-python software project are documented. We find that miriad-python provides an extremely effective environment for prototyping new interferometric software, though certain existing packages provide far more infrastructure for some applications. While equivalent software written in compiled languages can be much faster than Python, there are many situations in which execution time is profitably exchanged for speed of development, code readability, accessibility to nonexpert programmers, quick interlinking with foreign software packages, and other virtues of the Python language.

  1. Active gated imaging for automotive safety applications

    NASA Astrophysics Data System (ADS)

    Grauer, Yoav; Sonn, Ezri

    2015-03-01

    The paper presents the Active Gated Imaging System (AGIS), in relation to the automotive field. AGIS is based on a fast gated-camera equipped with a unique Gated-CMOS sensor, and a pulsed Illuminator, synchronized in the time domain to record images of a certain range of interest which are then processed by computer vision real-time algorithms. In recent years we have learned the system parameters which are most beneficial to night-time driving in terms of; field of view, illumination profile, resolution and processing power. AGIS provides also day-time imaging with additional capabilities, which enhances computer vision safety applications. AGIS provides an excellent candidate for camera-based Advanced Driver Assistance Systems (ADAS) and the path for autonomous driving, in the future, based on its outstanding low/high light-level, harsh weather conditions capabilities and 3D potential growth capabilities.

  2. Limiting Factors in Underwater Imaging Applications

    DTIC Science & Technology

    2010-01-14

    Underwater vision and diver visibility is one of the key research nd application topics dating back at least 150 years, when the Secchi disk was believed...1972, pp. 49-55. 16. Goodman J. W., Introduction to Fourier Optics: Roberts & Company Publishers, 2005. 17. Hou W.t et al., "Why does the Secchi ... disk disappear? An imaging perspective." Opt. Express, vol. 15, p. 2791-2802, March 19 2007. 18. Hou W. and Weidemann A., "Diver visibility: why

  3. Polarimetric Hyperspectral Imaging Systems and Applications

    NASA Technical Reports Server (NTRS)

    Cheng, Li-Jen; Mahoney, Colin; Reyes, George; Baw, Clayton La; Li, G. P.

    1996-01-01

    This paper reports activities in the development of AOTF Polarimetric Hyperspectral Imaging (PHI) Systems at JPL along with field observation results for illustrating the technology capabilities and advantages in remote sensing. In addition, the technology was also used to measure thickness distribution and structural imperfections of silicon-on-silicon wafers using white light interference phenomenon for demonstrating the potential in scientific and industrial applications.

  4. Interferometric synthetic aperture radar studies of Alaska volcanoes

    USGS Publications Warehouse

    Lu, Zhiming; Wicks, C.; Power, J.; Dzurisin, D.; Thatcher, W.; Masterlark, Timothy

    2002-01-01

    Interferometric synthetic aperture radar (InSAR) imaging is a recently developed geodetic technique capable of measuring ground-surface deformation with centimeter to subcentimeter vertical precision and spatial resolution of tens-of-meter over a relatively large region (~104 km2). The spatial distribution of surface deformation data, derived from InSAR images, enables the construction of detailed mechanical models to enhance the study of magmatic and tectonic processes associated with volcanoes. This paper summarizes our recent InSAR studies of several Alaska volcanoes, which include Okmok, Akutan, Kiska, Augustine, Westdahl, and Peulik volcanoes.

  5. Process for combining multiple passes of interferometric SAR data

    DOEpatents

    Bickel, Douglas L.; Yocky, David A.; Hensley, Jr., William H.

    2000-11-21

    Interferometric synthetic aperture radar (IFSAR) is a promising technology for a wide variety of military and civilian elevation modeling requirements. IFSAR extends traditional two dimensional SAR processing to three dimensions by utilizing the phase difference between two SAR images taken from different elevation positions to determine an angle of arrival for each pixel in the scene. This angle, together with the two-dimensional location information in the traditional SAR image, can be transformed into geographic coordinates if the position and motion parameters of the antennas are known accurately.

  6. Thermoelectric infrared imaging sensors for automotive applications

    NASA Astrophysics Data System (ADS)

    Hirota, Masaki; Nakajima, Yasushi; Saito, Masanori; Satou, Fuminori; Uchiyama, Makoto

    2004-07-01

    This paper describes three low-cost thermoelectric infrared imaging sensors having a 1,536, 2,304, and 10,800 element thermoelectric focal plane array (FPA) respectively and two experimental automotive application systems. The FPAs are basically fabricated with a conventional IC process and micromachining technologies and have a low cost potential. Among these sensors, the sensor having 2,304 elements provide high responsivity of 5,500 V/W and a very small size with adopting a vacuum-sealed package integrated with a wide-angle ZnS lens. One experimental system incorporated in the Nissan ASV-2 is a blind spot pedestrian warning system that employs four infrared imaging sensors. This system helps alert the driver to the presence of a pedestrian in a blind spot by detecting the infrared radiation emitted from the person"s body. The system can also prevent the vehicle from moving in the direction of the pedestrian. The other is a rearview camera system with an infrared detection function. This system consists of a visible camera and infrared sensors, and it helps alert the driver to the presence of a pedestrian in a rear blind spot. Various issues that will need to be addressed in order to expand the automotive applications of IR imaging sensors in the future are also summarized. This performance is suitable for consumer electronics as well as automotive applications.

  7. Smart pixel camera based signal processing in an interferometric test station for massive parallel inspection of MEMS and MOEMS

    NASA Astrophysics Data System (ADS)

    Styk, Adam; Lambelet, Patrick; Røyset, Arne; Kujawińska, Małgorzata; Gastinger, Kay

    2010-09-01

    The paper presents the electro-optical design of an interferometric inspection system for massive parallel inspection of Micro(Opto)ElectroMechanicalSystems (M(O)EMS). The basic idea is to adapt a micro-optical probing wafer to the M(O)EMS wafer under test. The probing wafer is exchangeable and contains a micro-optical interferometer array: a low coherent interferometer (LCI) array based on a Mirau configuration and a laser interferometer (LI) array based on a Twyman-Green configuration. The interference signals are generated in the micro-optical interferometers and are applied for M(O)EMS shape and deformation measurements by means of LCI and for M(O)EMS vibration analysis (the resonance frequency and spatial mode distribution) by means of LI. Distributed array of 5×5 smart pixel imagers detects the interferometric signals. The signal processing is based on the "on pixel" processing capacity of the smart pixel camera array, which can be utilised for phase shifting, signal demodulation or envelope maximum determination. Each micro-interferometer image is detected by the 140 × 146 pixels sub-array distributed in the imaging plane. In the paper the architecture of cameras with smart-pixel approach are described and their application for massive parallel electrooptical detection and data reduction is discussed. The full data processing paths for laser interferometer and low coherent interferometer are presented.

  8. Applications of superconducting bolometers in security imaging

    NASA Astrophysics Data System (ADS)

    Luukanen, A.; Leivo, M. M.; Rautiainen, A.; Grönholm, M.; Toivanen, H.; Grönberg, L.; Helistö, P.; Mäyrä, A.; Aikio, M.; Grossman, E. N.

    2012-12-01

    Millimeter-wave (MMW) imaging systems are currently undergoing deployment World-wide for airport security screening applications. Security screening through MMW imaging is facilitated by the relatively good transmission of these wavelengths through common clothing materials. Given the long wavelength of operation (frequencies between 20 GHz to ~ 100 GHz, corresponding to wavelengths between 1.5 cm and 3 mm), existing systems are suited for close-range imaging only due to substantial diffraction effects associated with practical aperture diameters. The present and arising security challenges call for systems that are capable of imaging concealed threat items at stand-off ranges beyond 5 meters at near video frame rates, requiring substantial increase in operating frequency in order to achieve useful spatial resolution. The construction of such imaging systems operating at several hundred GHz has been hindered by the lack of submm-wave low-noise amplifiers. In this paper we summarize our efforts in developing a submm-wave video camera which utilizes cryogenic antenna-coupled microbolometers as detectors. Whilst superconducting detectors impose the use of a cryogenic system, we argue that the resulting back-end complexity increase is a favorable trade-off compared to complex and expensive room temperature submm-wave LNAs both in performance and system cost.

  9. Adaptive Optics Retinal Imaging: Emerging Clinical Applications

    PubMed Central

    Godara, Pooja; Dubis, Adam M.; Roorda, Austin; Duncan, Jacque L.; Carroll, Joseph

    2010-01-01

    The human retina is a uniquely accessible tissue. Tools like scanning laser ophthalmoscopy (SLO) and spectral domain optical coherence tomography (SD-OCT) provide clinicians with remarkably clear pictures of the living retina. While the anterior optics of the eye permit such non-invasive visualization of the retina and associated pathology, these same optics induce significant aberrations that in most cases obviate cellular-resolution imaging. Adaptive optics (AO) imaging systems use active optical elements to compensate for aberrations in the optical path between the object and the camera. Applied to the human eye, AO allows direct visualization of individual rod and cone photoreceptor cells, RPE cells, and white blood cells. AO imaging has changed the way vision scientists and ophthalmologists see the retina, helping to clarify our understanding of retinal structure, function, and the etiology of various retinal pathologies. Here we review some of the advances made possible with AO imaging of the human retina, and discuss applications and future prospects for clinical imaging. PMID:21057346

  10. Adaptive optics retinal imaging: emerging clinical applications.

    PubMed

    Godara, Pooja; Dubis, Adam M; Roorda, Austin; Duncan, Jacque L; Carroll, Joseph

    2010-12-01

    The human retina is a uniquely accessible tissue. Tools like scanning laser ophthalmoscopy and spectral domain-optical coherence tomography provide clinicians with remarkably clear pictures of the living retina. Although the anterior optics of the eye permit such non-invasive visualization of the retina and associated pathology, the same optics induce significant aberrations that obviate cellular-resolution imaging in most cases. Adaptive optics (AO) imaging systems use active optical elements to compensate for aberrations in the optical path between the object and the camera. When applied to the human eye, AO allows direct visualization of individual rod and cone photoreceptor cells, retinal pigment epithelium cells, and white blood cells. AO imaging has changed the way vision scientists and ophthalmologists see the retina, helping to clarify our understanding of retinal structure, function, and the etiology of various retinal pathologies. Here, we review some of the advances that were made possible with AO imaging of the human retina and discuss applications and future prospects for clinical imaging.

  11. Interferometric inversion for passive imaging and navigation

    DTIC Science & Technology

    2017-05-01

    1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188...FA9550-15-1-0078 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Demanet, Laurent 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER...platform from geolocated sources. This project aims at quantifying resolution (i.e., the expected length scales of accuracy of this recovery) and the

  12. Solar Interferometric imaging from the Moon

    NASA Astrophysics Data System (ADS)

    Dame, L.; Martic, M.; Porteneuve, J.

    1994-06-01

    We present the concept of a Lunar Interferometer for Solar Physics. In particular we explain the rationale for a compact 2D array and we propose the use of a novel mechanical support structure based on linear mounting rods-these optimizing room and mass issues for transportation to the Moon.

  13. Applications review for a Space Program Imaging Radar (SPIR)

    NASA Technical Reports Server (NTRS)

    Simonett, D. S.

    1976-01-01

    The needs, applications, user support, research, and theoretical studies of imaging radar are reviewed. The applications of radar in water resources, minerals and petroleum exploration, vegetation resources, ocean radar imaging, and cartography are discussed. The advantages of space imaging radar are presented, and it is recommended that imaging radar be placed on the space shuttle.

  14. Adaptive optics simulations for imaging with the Large Binocular Telescope interferometer: a first application

    NASA Astrophysics Data System (ADS)

    Carbillet, Marcel; Correia, Serge; Femenia, Bruno; Riccardi, Armando

    2000-07-01

    In this contribution we present a first application of the ongoing numerical simulations that are carried out in order to study the adaptive optics (AO) correction and the subsequent imaging post-processing when observing with the Large Binocular Telescope (LBT) interferometer. The simulation tool used as a starting point for this study is the software package CAOS 2.0 (Code for Adaptive Optics Systems, version 2.0), for its AO-simulation capabilities and its modular structure. It is used here in order to generate the turbulence-corrupted and subsequently adaptive-optics- corrected interferometric point-spread functions corresponding to the simultaneous observation of both a scientific object and a reference star, for three parallactic angles corresponding to three observation runs during the night. The obtained data are therefore used as the inputs of a multiple deconvolution method planned for imaging with the LBT interferometer. As an example, we have simulated the observation, in the R-band, of a Betelgeuse-like stellar object of 15th magnitude, 30 mas diameter, and with a 3 mas bright spot, under two different conditions of turbulence and AO-correction (leading to Strehl ratios of approximately 0.15 and approximately 0.45, respectively). Final results are found to be very encouraging.

  15. Iterated unscented Kalman filter for phase unwrapping of interferometric fringes.

    PubMed

    Xie, Xianming

    2016-08-22

    A fresh phase unwrapping algorithm based on iterated unscented Kalman filter is proposed to estimate unambiguous unwrapped phase of interferometric fringes. This method is the result of combining an iterated unscented Kalman filter with a robust phase gradient estimator based on amended matrix pencil model, and an efficient quality-guided strategy based on heap sort. The iterated unscented Kalman filter that is one of the most robust methods under the Bayesian theorem frame in non-linear signal processing so far, is applied to perform simultaneously noise suppression and phase unwrapping of interferometric fringes for the first time, which can simplify the complexity and the difficulty of pre-filtering procedure followed by phase unwrapping procedure, and even can remove the pre-filtering procedure. The robust phase gradient estimator is used to efficiently and accurately obtain phase gradient information from interferometric fringes, which is needed for the iterated unscented Kalman filtering phase unwrapping model. The efficient quality-guided strategy is able to ensure that the proposed method fast unwraps wrapped pixels along the path from the high-quality area to the low-quality area of wrapped phase images, which can greatly improve the efficiency of phase unwrapping. Results obtained from synthetic data and real data show that the proposed method can obtain better solutions with an acceptable time consumption, with respect to some of the most used algorithms.

  16. Medical applications of digital image morphing.

    PubMed

    Penska, Keith; Folio, Les; Bunger, Rolf

    2007-09-01

    The authors present a unique medical technical application for illustrating the success and/or failure of the physiological healing process as a dynamically morphed video. Two examples used in this report include the healing of a severely fractured humerus from an explosion in Iraq and the other of dramatic tissue destruction from a poisonous spider bite. For the humerus, several sequential x-rays obtained throughout orthopedic surgical procedures and the healing process were morphed together representing a time-lapsed video of the healing process. The end result is a video that demonstrates the healing process in an animation that radiologists envision and report to other clinicians. For the brown recluse spider bite, a seemingly benign skin lesion transforms into a wide gaping necrotic wound with dramatic appearance within days. This novel technique is not presented for readily apparent clinical advantage, rather, it may have more immediate application in providing treatment options to referring providers and/or patients, as well as educational value of healing or disease progression over time. Image morphing is one of those innovations that is just starting to come into its own. Morphing is an image processing technology that transforms one image into another by generating a series of intermediate synthetic images. It is the same process that Hollywood uses to turn people into animals in movies, for example. The ability to perform morphing, once restricted to high-end graphics workstations, is now widely available for desktop computers. The authors describe how a series of radiographic images were morphed into a short movie clip using readily available software and an average laptop. The resultant video showed the healing process of an open comminuted humerus fracture that helped demonstrate how amazingly the human body heals in a case presentation in a time-lapse fashion.

  17. Target identification and navigation performance modeling of a passive millimeter wave imager.

    PubMed

    Jacobs, Eddie L; Furxhi, Orges

    2010-07-01

    Human task performance using a passive interferometric millimeter wave imaging sensor is modeled using a task performance modeling approach developed by the U.S. Army Night Vision and Electronic Sensors Directorate. The techniques used are illustrated for an imaging system composed of an interferometric antenna array, optical upconversion, and image formation using a shortwave infrared focal plane array. Two tasks, target identification and pilotage, are modeled. The effects of sparse antenna arrays on task performance are considered. Applications of this model include system trade studies for concealed weapon identification, navigation in fog, and brownout conditions.

  18. Principles and clinical applications of strain imaging.

    PubMed

    Govind, Satish C; Kiotsekoglou, Anatoli; Gopal, Aasha S; Brodin, Lars Ake; Ramesh; Saha, Samir K

    2011-01-01

    applications, stronger would be the ground to resolve technical and clinical issues. Strain imaging in its present form cannot win the game alone in this era of multi-modality imaging, but it is almost certain that with continued advancement, tissue Doppler and speckle tracking echocardiography based strain could play a pivotal role in a variety of clinical situations providing much needed incremental information.

  19. Overview and Applications of UAVSAR's Multi-Squint Polarimetric Imaging Mode

    NASA Technical Reports Server (NTRS)

    Scott Hensley; Chen, Curtis; Michel, Thierry; Jones, Cathleen; Chapman, Bruce; Muellerschoen, Ron

    2011-01-01

    NASA's Jet Propulsion Laboratory has developed a reconfigurable polarimetric L-band synthetic aperture radar (SAR), specifically designed to acquire airborne repeat track interferometric (RTI) SAR data for application to monitoring surface deformation and vegetation structure measurements. The system employs a precision autopilot developed by NASA Dryden that allows the plane to fly precise trajectories usually within a 5 m tube. Also required for robust repeat pass applications is the ability to point the antenna in the same direction on repeat passes to a fraction of an azimuth beamwidth (8? for UAVSAR). This precise pointing is achieved using an electronically scanned antenna whose pointing is based on inertial navigation unit (INU) attitude angle data. The radar design is fully polarimetric with an 80 MHz bandwidth (2 m range resolution) and has a greater than 20 km range swath when flying at its nominal altitude of 12500 m. The ability to electronically steer the beam on a pulse-to-pulse basis has allowed a new mode of SAR data acquisition whereby the radar beam is steered to different squint angles on successive pulses thereby simultaneously generating images at multiple squint angles. This mode offers the possibility of generating vector deformation measurements with a single pair of repeat passes and to obtain greater kz diversity for vegetation studies with a reduced number of passes. This paper will present an overview of the mode, discuss its potential for deformation and vegetation, and show some examples using UAVSAR data.

  20. Overview and Applications of UAVSAR's Multi-Squint Polarimetric Imaging Mode

    NASA Technical Reports Server (NTRS)

    Scott Hensley; Chen, Curtis; Michel, Thierry; Jones, Cathleen; Chapman, Bruce; Muellerschoen, Ron

    2011-01-01

    NASA's Jet Propulsion Laboratory has developed a reconfigurable polarimetric L-band synthetic aperture radar (SAR), specifically designed to acquire airborne repeat track interferometric (RTI) SAR data for application to monitoring surface deformation and vegetation structure measurements. The system employs a precision autopilot developed by NASA Dryden that allows the plane to fly precise trajectories usually within a 5 m tube. Also required for robust repeat pass applications is the ability to point the antenna in the same direction on repeat passes to a fraction of an azimuth beamwidth (8? for UAVSAR). This precise pointing is achieved using an electronically scanned antenna whose pointing is based on inertial navigation unit (INU) attitude angle data. The radar design is fully polarimetric with an 80 MHz bandwidth (2 m range resolution) and has a greater than 20 km range swath when flying at its nominal altitude of 12500 m. The ability to electronically steer the beam on a pulse-to-pulse basis has allowed a new mode of SAR data acquisition whereby the radar beam is steered to different squint angles on successive pulses thereby simultaneously generating images at multiple squint angles. This mode offers the possibility of generating vector deformation measurements with a single pair of repeat passes and to obtain greater kz diversity for vegetation studies with a reduced number of passes. This paper will present an overview of the mode, discuss its potential for deformation and vegetation, and show some examples using UAVSAR data.

  1. Applications of scientific imaging in environmental toxicology

    NASA Astrophysics Data System (ADS)

    El-Demerdash, Aref M.

    The national goals of clean air, clean water, and healthy ecosystems are a few of the primary forces that drive the need for better environmental monitoring. As we approach the end of the 1990s, the environmental questions at regional to global scales are being redefined and refined in the light of developments in environmental understanding and technological capability. Research in the use of scientific imaging data for the study of the environment is urgently needed in order to explore the possibilities of utilizing emerging new technologies. The objective of this research proposal is to demonstrate the usability of a wealth of new technology made available in the last decade to providing a better understanding of environmental problems. Research is focused in two imaging techniques macro and micro imaging. Several examples of applications of scientific imaging in research in the field of environmental toxicology were presented. This was achieved on two scales, micro and macro imaging. On the micro level four specific examples were covered. First, the effect of utilizing scanning electron microscopy as an imaging tool in enhancing taxa identification when studying diatoms was presented. Second, scanning electron microscopy combined with energy dispersive x-ray analyzer were demonstrated as a valuable and effective tool for identifying and analyzing household dust samples. Third, electronic autoradiography combined with FT-IR microscopy were used to study the distribution pattern of [14C]-Malathion in rats as a result of dermal exposure. The results of the autoradiography made on skin sections of the application site revealed the presence of [ 14C]-activity in the first region of the skin. These results were evidenced by FT-IR microscopy. The obtained results suggest that the penetration of Malathion into the skin and other tissues is vehicle and dose dependent. The results also suggest the use of FT-IR microscopy imaging for monitoring the disposition of

  2. Tangential Velocity Measurement Using Interferometric MTI Radar

    SciTech Connect

    DOERRY, ARMIN W.; MILESHOSKY, BRIAN P.; BICKEL, DOUGLAS L.

    2002-11-01

    An Interferometric Moving Target Indicator radar can be used to measure the tangential velocity component of a moving target. Multiple baselines, along with the conventional radial velocity measurement, allow estimating the true 3-D velocity vector of a target.

  3. Application of GFP imaging in cancer.

    PubMed

    Hoffman, Robert M

    2015-04-01

    Multicolored proteins have allowed the color-coding of cancer cells growing in vivo and enabled the distinction of host from tumor with single-cell resolution. Non-invasive imaging with fluorescent proteins enabled the dynamics of metastatic cancer to be followed in real time in individual animals. Non-invasive imaging of cancer cells expressing fluorescent proteins has allowed the real-time determination of efficacy of candidate antitumor and antimetastatic agents in mouse models. The use of fluorescent proteins to differentially label cancer cells in the nucleus and cytoplasm can visualize the nuclear-cytoplasmic dynamics of cancer cells in vivo including: mitosis, apoptosis, cell-cycle position, and differential behavior of nucleus and cytoplasm that occurs during cancer-cell deformation and extravasation. Recent applications of the technology described here include linking fluorescent proteins with cell-cycle-specific proteins such that the cells change color from red to green as they transit from G1 to S phases. With the macro- and micro-imaging technologies described here, essentially any in vivo process can be imaged, giving rise to the new field of in vivo cell biology using fluorescent proteins.

  4. Diffusion weighted imaging: Technique and applications

    PubMed Central

    Baliyan, Vinit; Das, Chandan J; Sharma, Raju; Gupta, Arun Kumar

    2016-01-01

    Diffusion weighted imaging (DWI) is a method of signal contrast generation based on the differences in Brownian motion. DWI is a method to evaluate the molecular function and micro-architecture of the human body. DWI signal contrast can be quantified by apparent diffusion coefficient maps and it acts as a tool for treatment response evaluation and assessment of disease progression. Ability to detect and quantify the anisotropy of diffusion leads to a new paradigm called diffusion tensor imaging (DTI). DTI is a tool for assessment of the organs with highly organised fibre structure. DWI forms an integral part of modern state-of-art magnetic resonance imaging and is indispensable in neuroimaging and oncology. DWI is a field that has been undergoing rapid technical evolution and its applications are increasing every day. This review article provides insights in to the evolution of DWI as a new imaging paradigm and provides a summary of current role of DWI in various disease processes. PMID:27721941

  5. Airborne Radar Interferometric Repeat-Pass Processing

    NASA Technical Reports Server (NTRS)

    Hensley, Scott; Michel, Thierry R.; Jones, Cathleen E.; Muellerschoen, Ronald J.; Chapman, Bruce D.; Fore, Alexander; Simard, Marc; Zebker, Howard A.

    2011-01-01

    Earth science research often requires crustal deformation measurements at a variety of time scales, from seconds to decades. Although satellites have been used for repeat-track interferometric (RTI) synthetic-aperture-radar (SAR) mapping for close to 20 years, RTI is much more difficult to implement from an airborne platform owing to the irregular trajectory of the aircraft compared with microwave imaging radar wavelengths. Two basic requirements for robust airborne repeat-pass radar interferometry include the ability to fly the platform to a desired trajectory within a narrow tube and the ability to have the radar beam pointed in a desired direction to a fraction of a beam width. Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) is equipped with a precision auto pilot developed by NASA Dryden that allows the platform, a Gulfstream III, to nominally fly within a 5 m diameter tube and with an electronically scanned antenna to position the radar beam to a fraction of a beam width based on INU (inertial navigation unit) attitude angle measurements.

  6. Demodulating interferometric and FBG sensors in the spectral domain

    NASA Astrophysics Data System (ADS)

    Inaudi, Daniele; Posenato, Daniele; Glisic, Branko; Miller, Jeff; Haber, Todd; Graver, Tom

    2005-05-01

    Long-gauge SOFO sensors have been in use for the last 10 years for the monitoring of civil, geotechnical, oil & Fiber optic sensing systems are increasingly recognized as a very attractive choice for structural health monitoring. Moving form demonstration project to industrial applications requires an integrated approach where the most appropriate technologies are combined to meet the user's requirements. In this context it is often necessary and desirable to combine different sensing technologies in the same project. A bridge-monitoring project might for example require long-gauge interferometric sensors to monitor the concrete deck, interferometric inclinometers for the piles and fiber Bragg grating sensors for the monitoring of the strains in the steel beams and for measuring temperatures. Although fiber optic sensors relying on different technologies can easily be combined at the packaging and cable levels, they often require dedicated instruments to be demodulated. A unified demodulation system would therefore be very attractive. This paper describes a technique relying on the analysis of reflected spectra and allowing the demodulation of interferometric (Michelson or Faby-Perot) sensors and fiber Bragg grating sensors with a single measurement system. It also compares the obtained performance in terms of resolution and dynamic range with the available dedicated systems.

  7. Creation of DICOM--aware applications using ImageJ.

    PubMed

    Barboriak, Daniel P; Padua, Anthony O; York, Gerald E; Macfall, James R

    2005-06-01

    The demand for image-processing software for radiology applications has been increasing, fueled by advancements in both image-acquisition and image-analysis techniques. The utility of existing image-processing software is often limited by cost, lack of flexibility, and/or specific hardware requirements. In particular, many existing packages cannot directly utilize images formatted using the specifications in part 10 of the DICOM standard ("DICOM images"). We show how image analyses can be performed directly on DICOM images by using ImageJ, a free, Java-based image-processing package (http://rsb.info.nih.gov/ij/). We demonstrate how plug-ins written in our laboratory can be used along with the ImageJ macro script language to create flexible, low-cost, multiplatform image-processing applications that can be directed by information contained in the DICOM image header.

  8. Image Algebra Application to Image Measurement and Feature Extraction

    NASA Astrophysics Data System (ADS)

    Ritter, Gerhard X.; Wilson, Joseph N.; Davidson, Jennifer L.

    1989-03-01

    It has been well established that the AFATL (Air Force Armament Technical Laboratory) Image Algebra is capable of expressing all image-to-image transformations [1,2] and that it is ideally suited for parallel image transformations {3,4]. In this paper we show how the algebra can also be applied to compactly express image-to-feature transforms including such sequential image-to-feature transforms as chain coding.

  9. Hyperspectral imaging: future applications in security systems

    NASA Astrophysics Data System (ADS)

    Bürsing, Helge; Gross, Wolfgang

    2017-04-01

    The idea behind hyperspectral imagers (HSI) is to generate an image with hundreds of contiguous narrow channels, the so-called spectral bands. As each material has a specific spectral signature, robust detection and classification of specific materials is now achievable. Spectra can be characterized by narrow features in their signatures that broadband and multispectral cameras cannot resolve. As a result of technical progress, new HSI with higher spatial resolution and better signal-to-noise ratios have been developed. Additionally, it is possible to buy small HSI that weigh less than 1 kg, which opens up new applications in surveillance and monitoring with unmanned aerial systems (UAS). Despite the capabilities of hyperspectral data evaluation, HSI is applied to surprisingly few tasks. This is a result of the sheer amount of recorded data that needs to be analyzed and the complex data pre-processing when the sensors are not used in a controlled environment. Also, extensive research is required to find the most efficient solution for a given task. The goal of this letter is to introduce and compare the different sensor techniques, discuss potential use for applications in civil security and give an outlook of future challenges.

  10. Ultrawideband radar imaging system for biomedical applications

    SciTech Connect

    Jafari, H.M.; Liu, W.; Hranilovic, S.; Deen, M.J.

    2006-05-15

    Ultrawideband (UWB) (3-10 GHz) radar imaging systems offer much promise for biomedical applications such as cancer detection because of their good penetration and resolution characteristics. The underlying principle of UWB cancer detection is a significant contrast in dielectric properties, which is estimated to be greater than 2:1 between normal and cancerous tissue, compared to a few-percent contrast in radiographic density exploited by x rays. This article presents a feasibility study of the UWB imaging of liver cancer tumors, based on the frequency-dependent finite difference time domain method. The reflection, radiation, and scattering properties of UWB pulses as they propagate through the human body are studied. The reflected and back-scattered electromagnetic energies from cancer tumors inside the liver are also investigated. An optimized, ultrawideband antenna was designed for near field operation, allowing for the reduction of the air-skin interface. It will be placed on the fat-liver tissue phantom with a malignant tumor stimulant. By performing an incremental scan over the phantom and removing early time artifacts, including reflection from the antenna ends, images based on the back-scattered signal from the tumor can be constructed. This research is part of our effort to develop a UWB cancer detection system with good detection and localization properties.

  11. A novel application of musculoskeletal ultrasound imaging.

    PubMed

    Eranki, Avinash; Cortes, Nelson; Ferenček, Zrinka Gregurić; Sikdar, Siddhartha

    2013-09-17

    Ultrasound is an attractive modality for imaging muscle and tendon motion during dynamic tasks and can provide a complementary methodological approach for biomechanical studies in a clinical or laboratory setting. Towards this goal, methods for quantification of muscle kinematics from ultrasound imagery are being developed based on image processing. The temporal resolution of these methods is typically not sufficient for highly dynamic tasks, such as drop-landing. We propose a new approach that utilizes a Doppler method for quantifying muscle kinematics. We have developed a novel vector tissue Doppler imaging (vTDI) technique that can be used to measure musculoskeletal contraction velocity, strain and strain rate with sub-millisecond temporal resolution during dynamic activities using ultrasound. The goal of this preliminary study was to investigate the repeatability and potential applicability of the vTDI technique in measuring musculoskeletal velocities during a drop-landing task, in healthy subjects. The vTDI measurements can be performed concurrently with other biomechanical techniques, such as 3D motion capture for joint kinematics and kinetics, electromyography for timing of muscle activation and force plates for ground reaction force. Integration of these complementary techniques could lead to a better understanding of dynamic muscle function and dysfunction underlying the pathogenesis and pathophysiology of musculoskeletal disorders.

  12. A Novel Application of Musculoskeletal Ultrasound Imaging

    PubMed Central

    Eranki, Avinash; Cortes, Nelson; Ferenček, Zrinka Gregurić; Sikdar, Siddhartha

    2013-01-01

    Ultrasound is an attractive modality for imaging muscle and tendon motion during dynamic tasks and can provide a complementary methodological approach for biomechanical studies in a clinical or laboratory setting. Towards this goal, methods for quantification of muscle kinematics from ultrasound imagery are being developed based on image processing. The temporal resolution of these methods is typically not sufficient for highly dynamic tasks, such as drop-landing. We propose a new approach that utilizes a Doppler method for quantifying muscle kinematics. We have developed a novel vector tissue Doppler imaging (vTDI) technique that can be used to measure musculoskeletal contraction velocity, strain and strain rate with sub-millisecond temporal resolution during dynamic activities using ultrasound. The goal of this preliminary study was to investigate the repeatability and potential applicability of the vTDI technique in measuring musculoskeletal velocities during a drop-landing task, in healthy subjects. The vTDI measurements can be performed concurrently with other biomechanical techniques, such as 3D motion capture for joint kinematics and kinetics, electromyography for timing of muscle activation and force plates for ground reaction force. Integration of these complementary techniques could lead to a better understanding of dynamic muscle function and dysfunction underlying the pathogenesis and pathophysiology of musculoskeletal disorders. PMID:24084063

  13. Magnetic resonance imaging: Principles and applications

    SciTech Connect

    Kean, D.; Smith, M.

    1986-01-01

    This text covers the physics underlying magnetic resonance (MR) imaging; pulse sequences; image production; equipment; aspects of clinical imaging; and the imaging of the head and neck, thorax, abdomen and pelvis, and musculoskeletal system; and MR imaging. The book provides about 150 examples of MR images that give an overview of the pathologic conditions imaged. There is a discussion of the physics of MR imaging and also on the spin echo.

  14. Non-interferometric phase retrieval using refractive index manipulation

    NASA Astrophysics Data System (ADS)

    Chen, Chyong-Hua; Hsu, Hsin-Feng; Chen, Hou-Ren; Hsieh, Wen-Feng

    2017-04-01

    We present a novel, inexpensive and non-interferometric technique to retrieve phase images by using a liquid crystal phase shifter without including any physically moving parts. First, we derive a new equation of the intensity-phase relation with respect to the change of refractive index, which is similar to the transport of the intensity equation. The equation indicates that this technique is unneeded to consider the variation of magnifications between optical images. For proof of the concept, we use a liquid crystal mixture MLC 2144 to manufacture a phase shifter and to capture the optical images in a rapid succession by electrically tuning the applied voltage of the phase shifter. Experimental results demonstrate that this technique is capable of reconstructing high-resolution phase images and to realize the thickness profile of a microlens array quantitatively.

  15. Feasibility of coupling Euro50 interferometrically to a Carlina hypertelescope

    NASA Astrophysics Data System (ADS)

    Labeyrie, Antoine

    2004-07-01

    The interferometric coupling of an ELT with a large multi-aperture imaging interferometer can open new areas of science on compact objects. Numerical simulations indeed show that the combined image retains respectively the high luminosity and the high angular resolution of both instruments. The Canarian site envisaged for the Euro-50 is adjacent to the large Caldera de Taburiente crater, a favorable site for an optical and dilute form of the Arecibo radio-telescope. Our preliminary study indicates that the effective aperture size can exceed 1600 m if a balloon or kite is used to carry the focal optics, also receiving a coude beam from the Euro-50 if coupled. In spite of inherent limitations regarding field size and crowding, the 50 micro-arcsecond resolution thus achievable in visible snapshot images is of interest for stellar physics, active galactic nuclei and deep cosmological imaging of remote galaxies.

  16. Non-interferometric phase retrieval using refractive index manipulation

    PubMed Central

    Chen, Chyong-Hua; Hsu, Hsin-Feng; Chen, Hou-Ren; Hsieh, Wen-Feng

    2017-01-01

    We present a novel, inexpensive and non-interferometric technique to retrieve phase images by using a liquid crystal phase shifter without including any physically moving parts. First, we derive a new equation of the intensity-phase relation with respect to the change of refractive index, which is similar to the transport of the intensity equation. The equation indicates that this technique is unneeded to consider the variation of magnifications between optical images. For proof of the concept, we use a liquid crystal mixture MLC 2144 to manufacture a phase shifter and to capture the optical images in a rapid succession by electrically tuning the applied voltage of the phase shifter. Experimental results demonstrate that this technique is capable of reconstructing high-resolution phase images and to realize the thickness profile of a microlens array quantitatively. PMID:28387382

  17. Interferometric, astrometric, and photometric studies of Epsilon Aurigae: Seeing the disk around a distant star

    NASA Astrophysics Data System (ADS)

    Kloppenborg, Brian

    2012-05-01

    Epsilon (epsilon) Aurigae is a binary star system that has baffled astronomers for 170 years. In 1821 it was first noticed that the star system had dimmed by nearly 50%. After many decades of photometric monitoring, the 27.1 year period was finally established in 1903. A few years later, in 1912, Henry Norris Russell published the first analytic methods for binary star analysis. Later application of these formulae came to an interesting conclusion; the system was composed of two stars: the visible F-type supergiant, and an equally massive, but yet photometrically and spectroscopically invisible, companion. Several theories were advanced to explain this low-light to high-mass conundrum, eventually settling on the notion that the companion object is obscured from view by a disk of opaque material. With this topic solved, the debate shifted the evolutionary state of the system. Two scenarios became dominant: the system is either relativity young, and composed of a massive, 15 Mo (solar mass), F-type supergiant and a nearly equally massive main sequence companion inside of the disk; or a much older and significantly less massive, 4 Mo, F-type post-asymptotic giant branch object with a more massive, 6 Mo, companion surrounded by a debris disk. In this dissertation I disentangle the two evolutionary states by comparing the photometric behavior of the F-type star to known supergiant and post-asymptotic giant branch objects; and deriving a dynamical mass for the two components using astrometric, radial velocity, and interferometric data. Along with this, I provide the first interferometric images during the eclipse which prove the 50% dimming is indeed caused by an opaque disk. The first chapter presents the reader with the status quo of epsilon Aurigae research and the topics I wish to address in this dissertation. Chapter two presents an analysis of nearly 30 years of photometry on the system, concluding the star periodically exhibits stable pulsation on 1/3 orbital

  18. Wavemill Product Assessment- Defining Products and Evaluating Potential Performance from a Novel Spaceborne Interferometric SAR

    NASA Astrophysics Data System (ADS)

    Cotton, P. D.; Gommenginger, C.; Martin, A.; Marquez, J.; Burbidge, G.; Quilfen, Y.; Chapron, B.; Reppucci, A.; Buck, C.

    2016-08-01

    Ocean Surface Currents are one of the most important ocean properties for oceanographers and operators in the maritime domain. Improved monitoring of ocean currents is systematically the number one requirement that emerges from any science or end user requirement surveys.Wavemill is a novel hybrid interferometric SAR system first proposed by ESA/ESTEC [Buck, 2005]. It offers the possibility of generating two-dimensional wide swath, high resolution, high precision maps of surface current vectors and ocean topography [Buck et al., 2009]. Based on a single spacecraft, it avoids the difficulties of synchronisation and baseline estimation associated with other interferometric SAR systems based on two or more satellites (e.g. the "cartwheel" or "helix" concept).The Wavemill concept has developed steadily since its first inception in 2005. A number of Wavemill studies in recent years have gradually put together facts and figures to support the case for Wavemill as a possible space-borne mission.The Wavemill Product Assessment study (WaPA) aimed to define the scientific capabilities and limitations of a spaceborne Wavemill instrument in preparation for a possible submission of the Wavemill concept as a candidate Earth Explorer Core mission. The WaPA project team brought together expert scientists and engineers in the field of SAR imaging of ocean currents, and included the National Oceanography Centre (UK), Starlab (Spain), IFREMER (France) and Airbus Defence and Space (UK). Overall project management was provided by Satellite Oceanographic Consultants (UK). The approach taken included:- A review of SAR imaging of ocean currents in along-track interferometric mode to learn from previous experiments and modelling what key phenomena need to be accounted for to determine the true performance of a spaceborne Wavemill system- Validation of proposed Wavemill primary products based on Wavemill airborne proof-of-concept data and numerical simulations to determine the capabilities

  19. Near-infrared spectroscopic tissue imaging for medical applications

    DOEpatents

    Demos, Stavros; Staggs, Michael C.

    2006-12-12

    Near infrared imaging using elastic light scattering and tissue autofluorescence are explored for medical applications. The approach involves imaging using cross-polarized elastic light scattering and tissue autofluorescence in the Near Infra-Red (NIR) coupled with image processing and inter-image operations to differentiate human tissue components.

  20. Near-infrared spectroscopic tissue imaging for medical applications

    DOEpatents

    Demos; Stavros , Staggs; Michael C.

    2006-03-21

    Near infrared imaging using elastic light scattering and tissue autofluorescence are explored for medical applications. The approach involves imaging using cross-polarized elastic light scattering and tissue autofluorescence in the Near Infra-Red (NIR) coupled with image processing and inter-image operations to differentiate human tissue components.

  1. Computational Phase Imaging for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Nguyen, Tan Huu

    laser comes at the expense of speckles, which degrades image quality. Therefore, solutions purely based on physical modeling and computations to remove these artifacts, using white-light illumination, are highly desirable. Here, using physical optics, we develop a theoretical model that accurately explains the effects of partial coherence on image information and phase information. The model is further combined with numerical processing to suppress the artifacts, and recover the correct phase information. The third topic is devoted to applying QPI to clinical applications. Traditionally, stained tissues are used in prostate cancer diagnosis instead. The reason is that tissue samples used in diagnosis are nearly transparent under bright field inspection if unstained. Contrast-enhanced microscopy techniques, e.g., phase contrast microscopy (PC) and differential interference contrast microscopy (DIC), can render visibility of the untagged samples with high throughput. However, since these methods are intensity-based, the contrast of acquired images varies significantly from one imaging facility to another, preventing them from being used in diagnosis. Inheriting the merits of PC, SLIM produces phase maps, which measure the refractive index of label-free samples. However, the maps measured by SLIM are not affected by variation in imaging conditions, e.g., illumination, magnification, etc., allowing consistent imaging results when using SLIM across different clinical institutions. Here, we combine SLIM images with machine learning for automatic diagnosis results for prostate cancer. We focus on two diagnosis problems of automatic Gleason grading and cancer vs. non-cancer diagnosis. Finally, we introduce a new imaging modality, named Gradient Light Interference Microscopy (GLIM), which is able to image through optically thick samples using low spatial coherence illumination. The key benefit of GLIM comes from a large numerical aperture of the condenser, which is 0.55 NA

  2. Estimating and Removing Ionospheric Effects From GESS Interferometric SAR Imagery

    NASA Astrophysics Data System (ADS)

    Freedman, A. P.; Madsen, S. N.

    2002-05-01

    Many users of differential interferometry report image artifacts that cannot be attributed to surface deformation or terrain mismodeling. These artifacts are often ascribed to propagation delays due to the atmosphere or ionosphere. When atmospheric (primarily wet troposphere) delays can be ruled out, the ionosphere is usually blamed for the artifacts. There is rarely sufficient knowledge of the ionosphere at the spatial and temporal scales to prove or refute this assumption, however. In present-day, focused-based processing, large-scale ionospheric effects are typically removed in the baseline correction process before image formation. The large-scale mapping envisioned for the Global Earthquake Satellite System (GESS) precludes the use of baseline correction for removing anything other than physical orbit errors. Thus any effects induced by the ionosphere will be present in full measure. The ionosphere is a dispersive medium and produces several frequency-dependent effects on a radar signal, affecting both the resulting single-channel Synthetic Aperture Radar (SAR) imagery and two-channel interferometric imagery in a number of distinct ways. The signal propagation or group delay slows down the radar pulse relative to free space, while the phase delay advances the phase relative to that of free space. The Faraday rotation alters the polarization of the return signal. One may take advantage of the frequency dependence of the group and phase delays to evaluate the magnitude of the ionospheric total electron count (TEC). Global and large-scale ionospheric fluctuations are associated with solar UV excitation, and are modulated diurnally and seasonally. These can cause propagation delays at L-band of typically 10 to 20 meters, but up to a hundred meters and more in rare instances. Intermediate-scale disturbances (tens to hundreds of kilometers in extent) include traveling ionospheric disturbances (TIDs) and gravity waves induced by a variety of phenomena. These can

  3. Interferometric Rayleigh Scattering Measurement System

    NASA Technical Reports Server (NTRS)

    Bivolaru, Daniel (Inventor); Danehy, Paul M. (Inventor); Lee, Joseph W. (Inventor)

    2008-01-01

    A method and apparatus for performing simultaneous multi-point measurements of multiple velocity components in a gas flow is described. Pulses of laser light are directed to a measurement region of unseeded gas to produce Rayleigh or Mie scattered light in a plurality of directions. The Rayleigh or Mie scattered light is collected from multiple directions and combined in a single collimated light beam. The Rayleigh or Mie scattered light is then mixed together with a reference laser light before it is passed through a single planar Fabry-Perot interferometer for spectral analysis. At the output of the interferometer, a high-sensitivity CCD camera images the interference fringe pattern. This pattern contains the spectral and spatial information from both the Rayleigh scattered light and the reference laser light. Interferogram processing software extracts and analyzes spectral profiles to determine the velocity components of the gas flow at multiple points in the measurement region. The Rayleigh light rejected by the interferometer is recirculated to increase the accuracy and the applicability of the method for measurements at high temperatures without requiring an increase in the laser energy.

  4. Image and video fingerprinting: forensic applications

    NASA Astrophysics Data System (ADS)

    Lefebvre, Frédéric; Chupeau, Bertrand; Massoudi, Ayoub; Diehl, Eric

    2009-02-01

    Fighting movie piracy often requires automatic content identification. The most common technique to achieve this uses watermarking, but not all copyrighted content is watermarked. Video fingerprinting is an efficient alternative solution to identify content, to manage multimedia files in UGC sites or P2P networks and to register pirated copies with master content. When registering by matching copy fingerprints with master ones, a model of distortion can be estimated. In case of in-theater piracy, the model of geometric distortion allows the estimation of the capture location. A step even further is to determine, from passive image analysis only, whether different pirated versions were captured with the same camcorder. In this paper we present three such fingerprinting-based forensic applications: UGC filtering, estimation of capture location and source identification.

  5. Applications of high-resolution remote sensing image data

    NASA Technical Reports Server (NTRS)

    Strome, W. M.; Leckie, D.; Miller, J.; Buxton, R.

    1990-01-01

    There are many situations in which the image resolution of satellite data is insufficient to provide the detail required for resource management and environmental monitoring. This paper will focus on applications of high-resolution (0.4 to 10 m) airborne multispectral and imaging spectrometer data acquired in Canada using the MEIS II multispectral line imager and the PMI imaging spectrometer. Applications discussed will include forestry, mapping, and geobotany.

  6. Advanced MR Imaging in Pediatric Brain Tumors, Clinical Applications.

    PubMed

    Lequin, Maarten; Hendrikse, Jeroen

    2017-02-01

    Advanced MR imaging techniques, such as spectroscopy, perfusion, diffusion, and functional imaging, have improved the diagnosis of brain tumors in children and also play an important role in defining surgical as well as therapeutic responses in these patients. In addition to the anatomic or structural information gained with conventional MR imaging sequences, advanced MR imaging techniques also provide physiologic information about tumor morphology, metabolism, and hemodynamics. This article reviews the physiology, techniques, and clinical applications of diffusion-weighted and diffusion tensor imaging, MR spectroscopy, perfusion MR imaging, susceptibility-weighted imaging, and functional MR imaging in the setting of neuro-oncology.

  7. Autocorrelation artifacts in optical coherence tomography and interferometric synthetic aperture microscopy.

    PubMed

    Davis, Brynmor J; Ralston, Tyler S; Marks, Daniel L; Boppart, Stephen A; Carney, P Scott

    2007-06-01

    Interferometric synthetic aperture microscopy processing of optical coherence tomography data has been shown to allow computational focusing of en face planes that have traditionally been regarded as out of focus. It is shown that this focusing of the image also produces a defocusing effect in autocorrelation artifacts resulting from Fourier-domain data collection. This effect is verified experimentally and through simulation.

  8. Resolving phase ambiguities in the calibration of redundant interferometric arrays: implications for array design

    NASA Astrophysics Data System (ADS)

    Kurien, Binoy G.; Tarokh, Vahid; Rachlin, Yaron; Shah, Vinay N.; Ashcom, Jonathan B.

    2016-10-01

    We provide new results enabling robust interferometric image reconstruction in the presence of unknown aperture piston variation via the technique of redundant spacing calibration (RSC). The RSC technique uses redundant measurements of the same interferometric baseline with different pairs of apertures to reveal the piston variation among these pairs. In both optical and radio interferometry, the presence of phase-wrapping ambiguities in the measurements is a fundamental issue that needs to be addressed for reliable image reconstruction. In this paper, we show that these ambiguities affect recently developed RSC phasor-based reconstruction approaches operating on the complex visibilities, as well as traditional phase-based approaches operating on their logarithm. We also derive new sufficient conditions for an interferometric array to be immune to these ambiguities in the sense that their effect can be rendered benign in image reconstruction. This property, which we call wrap-invariance, has implications for the reliability of imaging via classical three-baseline phase closures as well as generalized closures. We show that wrap-invariance is conferred upon arrays whose interferometric graph satisfies a certain cycle-free condition. For cases in which this condition is not satisfied, a simple algorithm is provided for identifying those graph cycles which prevent its satisfaction. We apply this algorithm to diagnose and correct a member of a pattern family popular in the literature.

  9. A new method for bidimensional analysis of interferometric patterns of liquid films.

    PubMed

    Nogueira, Rui; Vazquez, Rosa; Mata, José Luís; Saramago, Benilde

    2005-06-01

    A new method for bidimensional analysis of interferometric patterns of wetting liquid films obtained with the captive bubble technique is described. This method replaces one-dimensional analysis along various intensity profiles with analysis of one average intensity profile. The advantage is to concentrate the surface characteristics of the whole film image into a single intensity profile.

  10. Modular hyperspectral imager enables multiple research applications

    NASA Astrophysics Data System (ADS)

    Hô, Nicolas; Prel, Florent; Moreau, Louis; Lavoie, Hugo; Bouffard, François; Dubé, Denis; Thériault, Jean-Marc; Vallières, Christian; Roy, Claude

    2012-09-01

    The MR-i spectroradiometer can support a wide range of applications from its architecture suited to multiple configurations. Its modular 4-port FTIR spectroradiometer architecture allows the simultaneous use of two different detector modules, direct or differential input(s) and multiple telescopes. In a given configuration, MR-i can combine a MWIR focal plane array and a LWIR focal plane array to provide an extended spectral range from the two imaging sensors. The two detector array modules are imaging the same scene allowing synchronized pixel-to-pixel spectral range combination. In another configuration, MR-i can combine two identical focal plane arrays with different attenuation factors and two interleaved integration times per detector array. This configuration generates four sets of hyperspectral data cubes with different dynamic ranges that can be combined to produce a single hyperspectral cube with unmatched dynamic range. This configuration is particularly well suited for high-speed, high-dynamic range characterization of targets such as aircrafts, flares, and explosions. In a third configuration, named iCATSI, the spectroradiometer is used in differential input configuration to provide efficient optical background subtraction. The iCATSI configuration features an MCT detectors array with spectral cutoff near 14 µm. This extended spectral range and high sensitivity allows the detection and identification of a wide range of chemicals.

  11. Observing the Sun with micro-interferometric devices: a didactic experiment

    NASA Astrophysics Data System (ADS)

    Defrère, D.; Absil, O.; Hanot, C.; Riaud, P.; Magette, A.; Marion, L.; Wertz, O.; Finet, F.; Steenackers, M.; Habraken, S.; Surdej, A.; Surdej, J.

    2014-04-01

    Measuring the angular diameter of celestial bodies has long been the main purpose of stellar interferometry and was its historical motivation. Nowadays, stellar interferometry is widely used for various other scientific purposes that require very high angular resolution measurements. In terms of angular spatial scales probed, observing distant stars located 10 to 100~pc away with a large hectometric interferometer is equivalent to observing our Sun with a micrometric baseline. Based on this idea, we have manufactured a set of micro-interferometric devices and tested them on the sky. The micro-interferometers consist of a chrome layer deposited on a glass plate that has been drilled by laser lithography to produce micron-sized holes with configurations corresponding to proposed interferometer projects such as CARLINA, ELSA, KEOPS, and OVLA. In this paper, we describe these interferometric devices and present interferometric observations of the Sun made in the framework of Astrophysics lectures being taught at the Liège University. By means of a simple photographic camera placed behind a micro-interferometric device, we observed the Sun and derived its angular size. This experiment provides a very didactic way to easily obtain fringe patterns similar to those that will be obtained with future large imaging arrays. A program written in C also allows to reproduce the various point spread functions and fringe patterns observed with the micro-interferometric devices for different types of sources, including the Sun.

  12. Time frequency requirements for radio interferometric earth physics

    NASA Technical Reports Server (NTRS)

    Thomas, J. B.; Fliegel, H. F.

    1973-01-01

    Two systems of VLBI (Very Long Baseline Interferometry) are now applicable to earth physics: an intercontinental baseline system using antennas of the NASA Deep Space Network, now observing at one-month intervals to determine UTI for spacecraft navigation; and a shorter baseline system called ARIES (Astronomical Radio Interferometric Earth Surveying), to be used to measure crustal movement in California for earthquake hazards estimation. On the basis of experience with the existing DSN system, a careful study has been made to estimate the time and frequency requirements of both the improved intercontinental system and of ARIES. Requirements for the two systems are compared and contrasted.

  13. Satellite emission radio interferometric earth surveying series - GPS geodetic system

    NASA Technical Reports Server (NTRS)

    Macdoran, P. F.

    1979-01-01

    A concept called SERIES (satellite emissions radio interferometric earth surveying) which makes use of GPS (global positioning system) radio transmissions without any satellite modifications, is described. Through the use of very long baseline interferometry (VLBI) and its calibration methods, 0.5 to 3 cm three dimensional baseline accuracy can be achieved over distances of 2 to 200 km respectively, with only 2 hours of on-site data acquisition. Attention is given to such areas as: the radio flux equivalent of GPS transmissions, synthesized delay precision, transmission and frequency subsystem requirements, tropospheric and ionospheric errors. Applications covered include geodesy and seismic tectonics.

  14. Investigation of laser holographic interferometric techniques for structure inspection

    NASA Technical Reports Server (NTRS)

    Chu, W. P.

    1973-01-01

    The application of laser holographic interferometric techniques for nondestructive inspection of material structures commonly used in aerospace works is investigated. Two types of structures, composite plate and solid fuel rocket engine motor casing, were examined. In conducting the experiments, both CW HeNe gas lasers and Q-switched ruby lasers were used as light sources for holographic recording setups. Different stressing schemes were investigated as to their effectiveness in generating maximum deformation at regions of structural weakness such as flaws and disbonds. Experimental results on stressing schemes such as thermal stressing, pressurized stressing, transducer excitation, and mechanical impact are presented and evaluated.

  15. Interferometric background reduction for femtosecond stimulated Raman scattering loss spectroscopy.

    PubMed

    Dobner, Sven; Cleff, Carsten; Fallnich, Carsten; Groß, Petra

    2012-11-07

    We present a purely optical method for background suppression in nonlinear spectroscopy based on linear interferometry. Employing an unbalanced Sagnac interferometer, an unprecedented background reduction of 17  dB over a broad bandwidth of 60  THz (2000  cm(-1)) is achieved and its application to femtosecond stimulated Raman scattering loss spectroscopy is demonstrated. Apart from raising the signal-to-background ratio in the measurement of the Raman intensity spectrum, this interferometric method grants access to the spectral phase of the resonant χ(3) contribution. The spectral phase becomes apparent as a dispersive lineshape and is reproduced numerically with a simple oscillator model.

  16. Development of image mappers for hyperspectral biomedical imaging applications

    PubMed Central

    Kester, Robert T.; Gao, Liang; Tkaczyk, Tomasz S.

    2010-01-01

    A new design and fabrication method is presented for creating large-format (>100 mirror facets) image mappers for a snapshot hyperspectral biomedical imaging system called an image mapping spectrometer (IMS). To verify this approach a 250 facet image mapper with 25 multiple-tilt angles is designed for a compact IMS that groups the 25 subpupils in a 5 × 5 matrix residing within a single collecting objective's pupil. The image mapper is fabricated by precision diamond raster fly cutting using surface-shaped tools. The individual mirror facets have minimal edge eating, tilt errors of <1 mrad, and an average roughness of 5.4 nm. PMID:20357875

  17. Viewpoints on Medical Image Processing: From Science to Application

    PubMed Central

    Deserno (né Lehmann), Thomas M.; Handels, Heinz; Maier-Hein (né Fritzsche), Klaus H.; Mersmann, Sven; Palm, Christoph; Tolxdorff, Thomas; Wagenknecht, Gudrun; Wittenberg, Thomas

    2013-01-01

    Medical image processing provides core innovation for medical imaging. This paper is focused on recent developments from science to applications analyzing the past fifteen years of history of the proceedings of the German annual meeting on medical image processing (BVM). Furthermore, some members of the program committee present their personal points of views: (i) multi-modality for imaging and diagnosis, (ii) analysis of diffusion-weighted imaging, (iii) model-based image analysis, (iv) registration of section images, (v) from images to information in digital endoscopy, and (vi) virtual reality and robotics. Medical imaging and medical image computing is seen as field of rapid development with clear trends to integrated applications in diagnostics, treatment planning and treatment. PMID:24078804

  18. Three-dimensional motion correction using speckle and phase for in vivo computed optical interferometric tomography

    PubMed Central

    Shemonski, Nathan D.; Ahn, Shawn S.; Liu, Yuan-Zhi; South, Fredrick A.; Carney, P. Scott; Boppart, Stephen A.

    2014-01-01

    Over the years, many computed optical interferometric techniques have been developed to perform high-resolution volumetric tomography. By utilizing the phase and amplitude information provided with interferometric detection, post-acquisition corrections for defocus and optical aberrations can be performed. The introduction of the phase, though, can dramatically increase the sensitivity to motion (most prominently along the optical axis). In this paper, we present two algorithms which, together, can correct for motion in all three dimensions with enough accuracy for defocus and aberration correction in computed optical interferometric tomography. The first algorithm utilizes phase differences within the acquired data to correct for motion along the optical axis. The second algorithm utilizes the addition of a speckle tracking system using temporally- and spatially-coherent illumination to measure motion orthogonal to the optical axis. The use of coherent illumination allows for high-contrast speckle patterns even when imaging apparently uniform samples or when highly aberrated beams cannot be avoided. PMID:25574426

  19. Michelson-type all-reflective interferometric autocorrelation in the VUV regime

    NASA Astrophysics Data System (ADS)

    Gebert, T.; Rompotis, D.; Wieland, M.; Karimi, F.; Azima, A.; Drescher, M.

    2014-07-01

    We demonstrate second-order interferometric autocorrelation of a pulse in the vacuum-ultraviolet (VUV) spectral range using an optical arrangement equivalent to a Michelson interferometer. In an all-reflective design, wavefront splitting is realized with two moveable interdigitated reflective gratings forming a diffraction pattern with well separated orders and an intensity distribution depending on the precisely adjustable path-length difference. An imaging time-of-flight spectrometer is able to spatially select ions created by nonlinear two-photon absorption in the focus of the zeroth diffraction order. This arrangement is used to demonstrate interferometric autocorrelation in krypton with femtosecond VUV pulses at 160 nm wavelength. In addition to the pulse duration, which is already accessible with non-collinear intensity autocorrelation, the full interferometric contrast of the presented approach enables us to extract also information on temporal phases.

  20. PAU-SA: a synthetic aperture interferometric radiometer test bed for potential improvements in future missions.

    PubMed

    Ramos-Perez, Isaac; Camps, Adriano; Bosch-Lluis, Xavi; Rodriguez-Alvarez, Nereida; Valencia-Domènech, Enric; Park, Hyuk; Forte, Giuseppe; Vall-Llosera, Merce

    2012-01-01

    The Soil Moisture and Ocean Salinity (SMOS) mission is an Earth Explorer Opportunity mission from the European Space Agency (ESA). Its goal is to produce global maps of soil moisture and ocean salinity using the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS). The purpose of the Passive Advanced Unit Synthetic Aperture (PAU-SA) instrument is to study and test some potential improvements that could eventually be implemented in future missions using interferometric radiometers such as the Geoestacionary Atmosferic Sounder (GAS), the Precipitation and All-weather Temperature and Humidity (PATH) and the Geostationary Interferometric Microwave Sounder (GIMS). Both MIRAS and PAU-SA are Y-shaped arrays with uniformly distributed antennas, but the receiver topology and the processing unit are quite different. The purpose of this work is to identify the elements in the MIRAS's design susceptible of improvement and apply them in the PAU-SA instrument demonstrator, to test them in view of these future interferometric radiometer missions.

  1. Achieving stabilization in interferometric logic operations.

    PubMed

    Zavalin, Andrey I; Shamir, Joseph; Vikram, Chandra S; Caulfield, H John

    2006-01-10

    Interferometric systems with amplitude beam splitters can implement reversible operations that, on detection, become Boolean operators. Being passive, they consume no energy, do not limit the operating bandwidth, and have negligible latency. Unfortunately, conventional interferometric systems are notoriously sensitive to uncontrolled disturbances. Here the use of polarization in a common-path interferometric logic gate with and without polarization beam splitters is explored as an attractive alternative to overcome those difficulties. Two of three device configurations considered offer significant stability and lower drive modulator voltage as advantages over the previous systems. The first experimental tests of such a system are reported. Common-path interferometry lends itself to even more stability and robustness by compatibility with no-air-gap, solid optics.

  2. 3D imaging system for biometric applications

    NASA Astrophysics Data System (ADS)

    Harding, Kevin; Abramovich, Gil; Paruchura, Vijay; Manickam, Swaminathan; Vemury, Arun

    2010-04-01

    There is a growing interest in the use of 3D data for many new applications beyond traditional metrology areas. In particular, using 3D data to obtain shape information of both people and objects for applications ranging from identification to game inputs does not require high degrees of calibration or resolutions in the tens of micron range, but does require a means to quickly and robustly collect data in the millimeter range. Systems using methods such as structured light or stereo have seen wide use in measurements, but due to the use of a triangulation angle, and thus the need for a separated second viewpoint, may not be practical for looking at a subject 10 meters away. Even when working close to a subject, such as capturing hands or fingers, the triangulation angle causes occlusions, shadows, and a physically large system that may get in the way. This paper will describe methods to collect medium resolution 3D data, plus highresolution 2D images, using a line of sight approach. The methods use no moving parts and as such are robust to movement (for portability), reliable, and potentially very fast at capturing 3D data. This paper will describe the optical methods considered, variations on these methods, and present experimental data obtained with the approach.

  3. Perfluorocarbon Compounds: Applications In Diagnostic Imaging

    NASA Astrophysics Data System (ADS)

    Mattrey, Robert F.

    1986-06-01

    Perfluorocarbon compounds (PFC's), well known in industry and of late as synthetic oxygen carriers, have a wide range of significant applications in diagnostic imaging. Their enhancement effect is detectable by ultrasound and magnetic resonance and if radiopaque, such as perfluoroctylbromide (PFOB), by standard radiography and computed tomography (CT). We have utilized PFOB as a CT contrast agent to enhance the blood pool, and as both a CT and an ultrasound contrast agent to enhance the liver, spleen, abscesses, infarctions, and tumors or any tissue where inflammatory cells can be found. PFC's, except for the echogenic enhancement of the vascular space on their first pass to the lung, do not enhance the blood pool on ultrasound. Otherwise, ultrasound applications are similar to those observed for CT. Fluosol, which was available for human trials, is not radiopaque and therefore served as an ultrasound contrast agent. In a preliminary clinical trial, Fluosol produced tumor enhancement in man at 1.6g/kg allowing the visualization of previously missed lesions and liver and spleen enhancement at 2.4g/kg allowing the visualization of previously missed non-enhancing lesions. Perfluorocarbon toxicity seems to be related to the constituents of the emulsion rather than the perfluorocarbon itself. Improvements in the emulsifier and emulsification technology has yielded stable emulsions at high concentrations and low toxicity.

  4. Interferometric sensor for plant fluorescence

    NASA Astrophysics Data System (ADS)

    Georgieva, E.; Heaps, W. S.; Middleton, E. M.; Campbell, P. K. E.; Corp, L. A.

    2009-08-01

    We present preliminary design studies and modeling results for a new system for the assessment of vegetation photosynthetic function, especially carbon uptake. Plant health and carbon uptake efficiency are of key consideration in assessing global productivity, biomass, changes in land cover and carbon dioxide flux. Chlorophyll fluorescence (ChlF) measurements are critical for understanding photosynthetic functioning, plant environmental stress responses and direct assessments of plant health. Plant ChlF occurs predominately in two broad emission bands in the red and infrared regions of the spectrum. Unfortunately, the fluorescence signal from vegetation is much weaker than, and obscured by, the reflected signal. This limitation can be overcome by acquiring ChlF measurements in atmospheric absorption lines. The Interferometric Sensor for Plant Fluorescence (ISPF) will measure plant ChlF using the Fraunhofer Line Discrimination approach. Fabry-Perot (FP) etalons will be used to restrict the measurement to radiation in the Solar Fraunhofer lines (SFL). An advantage of the proposed sensor design is that it will collect measurements using two sets of SFL at the same time. This technique increases the optical throughput producing a larger signal to noise ratio (SNR). The instrument is designed to have two channels for two different spectral regions. Each channel will have two sub-channels, one defined by a prefilter (Reference, Ref) and the other having a tunable FP etalon. The first subchannel (the Ref) will cover a relatively broad spectral range to include at least two Fraunhofer lines but for which the fluorescence signal will represent only a small fraction of total reflected light. The second subchannel will use a FP interferometer to restrict the detected light to include only the selected SFL where the ChlF in-filling is significant. A small change in the fluorescence will then produce an insignificant change in the Ref subchannel but a relatively large change in

  5. Optical Interferometric Parallel Data Processor

    NASA Technical Reports Server (NTRS)

    Breckinridge, J. B.

    1987-01-01

    Image data processed faster than in present electronic systems. Optical parallel-processing system effectively calculates two-dimensional Fourier transforms in time required by light to travel from plane 1 to plane 8. Coherence interferometer at plane 4 splits light into parts that form double image at plane 6 if projection screen placed there.

  6. A backscattered x-ray imager for medical applications

    NASA Astrophysics Data System (ADS)

    Morris, Eric Jude L.; Dibianca, Frank A.; Shukla, Hemant; Gulabani, Daya

    2005-04-01

    Conventional X-ray radiographic systems rely on transmitted photons for the production of images. Backscatter imaging makes use of the more abundant scattered photons for image formation. Specifically, incoherently (Compton) scattered X-ray photons are detected and used for image formation in this modality of medical imaging. However, additional information is obtained when the transmitted X-ray photons are also detected and used. Transmission radiography produces a two-dimensional image of a three dimensional system, therefore image information from a shallower object is often contaminated by image information from underlying objects. Backscattered x-ray imaging largely overcomes this deficiency by imaging depth selectively, which reduces corruption of shallow imaging information by information from deeper objects lying under it. Backscattered x-ray imaging may be particularly useful for examining anatomical structures at shallow depths beneath the skin. Some typical applications for such imaging might be breast imaging, middle ear imaging, imaging of skin melanomas, etc. Previous investigations, by way of theoretical calculations and computational simulations into the feasibility of this kind of imaging have uncovered high-contrast and SNR parameters. Simulations indicate that this method can be used for imaging relatively high-density objects at depths of up to approximately five centimeters below the surface. This paper presents both theoretical and experimental SNR results on this new medical imaging modality.

  7. Phase-stepping interferometric system for capturing instantaneous flow field under harsh environments

    NASA Astrophysics Data System (ADS)

    Burner, Alpheus W.; Yu, Enxi; Cha, Soyoung S.

    2003-04-01

    Interferometric reconstruction of a flow field usually consists of three steps. The first is to record interferograms, the second is to extract phase information from interferograms and the final is for numerical inversion of the phase data. In interferometric flow recording, test section enclosures and opaque models are frequently present, blocking a portion of the probing rays or restricting the view angle of the field to produce a partial data set especially for interferometric tomography. It also involves very harsh environments with external vibrations and disturbances of the ambient air. The ill-posed problem is susceptible to experimental noise and can produce serious distortions in reconstruction. Interferometric reconstruction of flow fields thus needs accurate phase information extraction. The major problem encountered in interferometry is that it is extremely sensitive to external disturbances including the vibration of the optical setup. This is true especially for aerodynamic wind tunnel testing. For successful application of interferometry to experimental fluid mechancis and heat/mass transfer, efficient mechanisms for accurate flow-field recording and information extraction are thus very necessary. In interferometric recording, use of the phase stepping techniques is desirable whenever possible, since they provide the most accuracy. However, they are not applicable under disturbing conditions; that is, under harsh environments. In an effort to provide accurate interferometric data, we device interferogram recording and reduction techniques. They are based on a phase-stepping method: however, applicable to harsh environments including wind tunnel testing. Here we present the governing concepts, investigation results, and application demonstration of our approaches for practical flow measurements. The developed approaches are tested through phoase extraction and 3D reconstruction of an experimental flow field, which is designed for future wind tunnel

  8. Compression of interferometric radio-astronomical data

    NASA Astrophysics Data System (ADS)

    Offringa, A. R.

    2016-11-01

    Context. The volume of radio-astronomical data is a considerable burden in the processing and storing of radio observations that have high time and frequency resolutions and large bandwidths. For future telescopes such as the Square Kilometre Array (SKA), the data volume will be even larger. Aims: Lossy compression of interferometric radio-astronomical data is considered to reduce the volume of visibility data and to speed up processing. Methods: A new compression technique named "Dysco" is introduced that consists of two steps: a normalization step, in which grouped visibilities are normalized to have a similar distribution; and a quantization and encoding step, which rounds values to a given quantization scheme using a dithering scheme. Several non-linear quantization schemes are tested and combined with different methods for normalizing the data. Four data sets with observations from the LOFAR and MWA telescopes are processed with different processing strategies and different combinations of normalization and quantization. The effects of compression are measured in image plane. Results: The noise added by the lossy compression technique acts similarly to normal system noise. The accuracy of Dysco is depending on the signal-to-noise ratio (S/N) of the data: noisy data can be compressed with a smaller loss of image quality. Data with typical correlator time and frequency resolutions can be compressed by a factor of 6.4 for LOFAR and 5.3 for MWA observations with less than 1% added system noise. An implementation of the compression technique is released that provides a Casacore storage manager and allows transparent encoding and decoding. Encoding and decoding is faster than the read/write speed of typical disks. Conclusions: The technique can be used for LOFAR and MWA to reduce the archival space requirements for storing observed data. Data from SKA-low will likely be compressible by the same amount as LOFAR. The same technique can be used to compress data from

  9. Applications of Digital Image Processing 11

    NASA Technical Reports Server (NTRS)

    Cho, Y. -C.

    1988-01-01

    A new technique, digital image velocimetry, is proposed for the measurement of instantaneous velocity fields of time dependent flows. A time sequence of single-exposure images of seed particles are captured with a high-speed camera, and a finite number of the single-exposure images are sampled within a prescribed period in time. The sampled images are then digitized on an image processor, enhanced, and superimposed to construct an image which is equivalent to a multiple exposure image used in both laser speckle velocimetry and particle image velocimetry. The superimposed image and a single-exposure Image are digitally Fourier transformed for extraction of information on the velocity field. A great enhancement of the dynamic range of the velocity measurement is accomplished through the new technique by manipulating the Fourier transform of both the single-exposure image and the superimposed image. Also the direction of the velocity vector is unequivocally determined. With the use of a high-speed video camera, the whole process from image acquisition to velocity determination can be carried out electronically; thus this technique can be developed into a real-time capability.

  10. Application of Uncooled Monolithic Thermoelectric Linear Arrays to Imaging Radiometers

    NASA Astrophysics Data System (ADS)

    Kruse, Paul W.

    Introduction Identification of Incipient Failure of Railcar Wheels Technical Description of the Model IR 1000 Imaging Radiometer Performance of the Model IR 1000 Imaging Radiometer Initial Application Summary Imaging Radiometer for Predictive and Preventive Maintenance Description Operation Specifications Summary References INDEX CONTENTS OF VOLUMES IN THIS SERIES

  11. Application of automatic image analysis in wood science

    Treesearch

    Charles W. McMillin

    1982-01-01

    In this paper I describe an image analysis system and illustrate with examples the application of automatic quantitative measurement to wood science. Automatic image analysis, a powerful and relatively new technology, uses optical, video, electronic, and computer components to rapidly derive information from images with minimal operator interaction. Such instruments...

  12. Applications of extreme ultraviolet compact lasers to nanopatterning and high resolution holographic imaging

    NASA Astrophysics Data System (ADS)

    Wachulak, Przemyslaw Wojciech

    This dissertation describes two applications of extreme ultraviolet light in nanotechnology. Using radiation with a wavelength in the extreme ultraviolet (EUV) range allows to reach scales much smaller than with a conventional visible illumination. The first part of this dissertation describes a series of experiments that allowed the patterning at nanometer scales with sub-100nm resolution. Two types of photoresists (positive tone - PMMA and negative tone - HSQ) were patterned over the areas up to a few mm2 with features as small as 45nm using the interferometric lithography approach, reaching resolution equivalent to the wavelength of the illumination - 46.9nm. For the nanopatterning experiments two types of interferometers were studied in detail: Lloyd's mirror configuration and an amplitude division interferometer. Both approaches are presented and their advantages and drawbacks are discussed. The second part of the dissertation focuses on holographic imaging with ultimate resolution approaching the wavelength of the illumination. Different experiments were performed using Gabor's in-line holographic configuration and its capabilities in the EUV region were discussed. Holographic imaging was performed with different objects: AFM probes, spherical markers and carbon nanotubes. The holograms were stored in a high resolution recording medium - photoresist, digitized with an atomic force microscope and numerically reconstructed using a code based on the Fresnel propagator algorithm achieving in the reconstructed images the ultimate wavelength resolution. The resolution for the carbon nano-tubes images was assessed by two independent measurements: the knife-edge test resulting 45.5nm and an algorithm based on the correlation between the reconstructed image and a set of templates with variable resolution obtained by successive Gaussian filtering. This analysis yielded a resolution ˜46nm. A similar algorithm that allowed for the simultaneous assessment of the

  13. Imaging sigma receptors: applications in drug development.

    PubMed

    Collier, Thomas Lee; Waterhouse, Rikki N; Kassiou, Michael

    2007-01-01

    Sigma receptors have been implicated in a myriad of cellular functions, biological processes and diseases. While the precise biological functions of sigma receptors have not been elucidated, recent work has shed some light on to these enigmatic systems. Sigma receptors have recently been a target of drug development related to psychiatric and neurological disorders. Sigma ligands have also been shown to modulate endothelial cell proliferation and can control angiogenesis which makes them a promising target for oncology applications. Other areas currently being investigated include treatment of gastrointestinal, cardiovascular, endocrine and immune system disorders. Of interest is that the human sigma-1 receptor gene contains a steroid binding component, and several gonadal steroids, including progesterone, testosterone and dehydroepiandrosterone (DHEA), interact with sigma-1 receptors. Of the steroids examined thus far, progesterone binds with the highest affinity to human sigma-1 receptors, with a reported affinity (Ki) as high as 30 nM while the other steroids exhibit lower affinity. For this and other reasons, sigma-1 receptors have been proposed as a link between the central nervous system and the endocrine and reproductive systems. Taken together, the above information highlights an important yet largely unexplored but promising area of research to examine the biological function and therapeutic potential of sigma receptors. This review provides an overview of the current knowledge of these sites with a focus on specific areas where in vivo sigma receptor imaging is currently being investigated.

  14. Note: Near infrared interferometric silicon wafer metrology.

    PubMed

    Choi, M S; Park, H M; Joo, K N

    2016-04-01

    In this investigation, two near infrared (NIR) interferometric techniques for silicon wafer metrology are described and verified with experimental results. Based on the transparent characteristic of NIR light to a silicon wafer, the fiber based spectrally resolved interferometry can measure the optical thickness of the wafer and stitching low coherence scanning interferometry can reconstruct entire surfaces of the wafer.

  15. Interferometric Synthetic Aperture Microwave Radiometers : an Overview

    NASA Technical Reports Server (NTRS)

    Colliander, Andreas; McKague, Darren

    2011-01-01

    This paper describes 1) the progress of the work of the IEEE Geoscience and Remote Sensing Society (GRSS) Instrumentation and Future Technologies Technical Committee (IFT-TC) Microwave Radiometer Working Group and 2) an overview of the development of interferometric synthetic aperture microwave radiometers as an introduction to a dedicated session.

  16. Interferometric Synthetic Aperture Microwave Radiometers : an Overview

    NASA Technical Reports Server (NTRS)

    Colliander, Andreas; McKague, Darren

    2011-01-01

    This paper describes 1) the progress of the work of the IEEE Geoscience and Remote Sensing Society (GRSS) Instrumentation and Future Technologies Technical Committee (IFT-TC) Microwave Radiometer Working Group and 2) an overview of the development of interferometric synthetic aperture microwave radiometers as an introduction to a dedicated session.

  17. Quantum Limits in Interferometric GW Antennas

    NASA Technical Reports Server (NTRS)

    Romano, R.; Barone, F.; Maddalena, P.; Solimeno, S.; Zaccaria, F.; Manko, M. A.; Manko, V. I.

    1996-01-01

    We discuss a model for interferometric GW antennas illuminated by a laser beam and a vacuum squeezed field. The sensitivity of the antenna will depend on the properties of the radiation entering the two ports and on the optical characteristics of the interferometer components, e.g. mirrors, beam-splitter, lenses.

  18. Interferometric study of a machine tool

    NASA Astrophysics Data System (ADS)

    Hoefling, Roland; Vaclavik, Jaroslav; Neigebauer, Reimund

    1996-09-01

    This paper describes the use of a non-destructive optical technique, digital speckle pattern interferometry, for the deformation analysis of a machine tool. An interferometric set-up has been designed and measurements of the milling head deformation have been made on the horizontal single spindle milling machine center.

  19. Detection of weak seismic waves in sea-ground interface by fiber-optic interferometric seismometer

    NASA Astrophysics Data System (ADS)

    Kamenev, O. T.; Petrov, Yu S.; Khiznyak, R. V.; Romashko, R. V.

    2016-08-01

    The possibility of detection of weak seismic waves in sea-ground interface by fiberoptic interferometric seismometer is experimentally demonstrated. High sensitivity of the seismometer to acceleration 10-7 m/s2 is provided by application of original multiturn fiber- optical sensing element. Long term stability of the seismometer operation is provided by feedback control of the interferometer working point.

  20. Ultrasonic NDE for composite materials using embedded fiber-optic interferometric sensors

    NASA Astrophysics Data System (ADS)

    Liu, Kexing; Ferguson, Suzanne M.; Davis, Andrew; McEwen, Keith; Measures, Raymond M.

    1991-04-01

    An interferometric fiber optic sensor using ordinary single-mode fibers is developed to detect elastic strain waves for nondestructive evaluation of composite materials. This fiber sensor has been embedded in both graphite/epoxy and Kevlar/epoxy composite specimens. Applications of the sensor for detection of acoustic emission and laser generated ultrasound are presented. Limitations of the sensor are also discussed.

  1. Polarization phase shifting interferometric technique for phase calibration of a reflective phase spatial light modulator

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Somparna; Sarkar, Sanjukta; Bhattacharya, Kallol; Hazra, Lakshminarayan

    2013-03-01

    Calibration of phase in spatial light modulators is a prerequisite for applications where a prespecified phase distribution needs to be implemented over the surface of the modulator. The present work proposes a full-field polarization phase shifting interferometric technique, based on the Twyman-Green interferometer, for the purpose.

  2. An Innovative Transponder-Based Interferometric Radar for Vibration Measurements

    SciTech Connect

    Coppi, F.; Cerutti, A.; Farina, P.; De Pasquale, G.; Novembrini, G.

    2010-05-28

    Ground-based radar interferometry has recently emerged as an innovative technology of remote sensing, able to accurately measure the static or dynamic displacement of several points of a structure. This technique in the last couple of years has been applied to different types of structures, such as bridges, towers and chimneys. This paper presents a prototype system developed by IDS, originally aimed at measuring the structural vibrations of helicopter rotor blades, based on an interferometric technique and constituted by combination of a radar sensor and a series of transponders installed on the target structure. The main advantages of this solution with respect to conventional interferometric radars, are related to the increased spatial resolution of the system, provided by the possibility to discriminate different transponders installed within the same resolution cell of the radar sensor, and to the reduction of the ambient noise (e.g. multi-path) on the radar measurement. The first feature allows the use of the microwave technology even on target areas with limited dimensions, such as industrial facilities, while the second aspect may extend the use of radar interferometric systems to complex scenarios, where multi-reflections are expected due to the presence of natural targets with high reflectivity to the radar signal. In the paper, the system and its major characteristics are first described; subsequently, application to the measurement of ambient vibration response of a lab set-up is summarized. Then the data acquired on a rotating mock-up are reported and analyzed to identify natural frequencies and mode shapes of the investigated structure.

  3. An Innovative Transponder-Based Interferometric Radar for Vibration Measurements

    NASA Astrophysics Data System (ADS)

    Coppi, F.; Cerutti, A.; Farina, P.; De Pasquale, G.; Novembrini, G.

    2010-05-01

    Ground-based radar interferometry has recently emerged as an innovative technology of remote sensing, able to accurately measure the static or dynamic displacement of several points of a structure. This technique in the last couple of years has been applied to different types of structures, such as bridges, towers and chimneys. This paper presents a prototype system developed by IDS, originally aimed at measuring the structural vibrations of helicopter rotor blades, based on an interferometric technique and constituted by combination of a radar sensor and a series of transponders installed on the target structure. The main advantages of this solution with respect to conventional interferometric radars, are related to the increased spatial resolution of the system, provided by the possibility to discriminate different transponders installed within the same resolution cell of the radar sensor, and to the reduction of the ambient noise (e.g. multi-path) on the radar measurement. The first feature allows the use of the microwave technology even on target areas with limited dimensions, such as industrial facilities, while the second aspect may extend the use of radar interferometric systems to complex scenarios, where multi-reflections are expected due to the presence of natural targets with high reflectivity to the radar signal. In the paper, the system and its major characteristics are first described; subsequently, application to the measurement of ambient vibration response of a lab set-up is summarized. Then the data acquired on a rotating mock-up are reported and analyzed to identify natural frequencies and mode shapes of the investigated structure.

  4. Optical imaging: current applications and future directions.

    PubMed

    Luker, Gary D; Luker, Kathryn E

    2008-01-01

    Optical techniques, such as bioluminescence and fluorescence, are emerging as powerful new modalities for molecular imaging in disease and therapy. Combining innovative molecular biology and chemistry, researchers have developed optical methods for imaging a variety of cellular and molecular processes in vivo, including protein interactions, protein degradation, and protease activity. Whereas optical imaging has been used primarily for research in small-animal models, there are several areas in which optical molecular imaging will translate to clinical medicine. In this review, we summarize recent advances in optical techniques for molecular imaging and the potential impact for clinical medicine.

  5. Damage Assessment Map from Interferometric Coherence

    NASA Astrophysics Data System (ADS)

    Yun, S.; Fielding, E. J.; Simons, M.; Rosen, P. A.; Owen, S. E.; Webb, F.

    2010-12-01

    Large earthquakes cause buildings to collapse, which often claims the lives of many. For example, 2010 Haiti earthquake killed about 230,000 people, with about 280,000 buildings collapsed or severely damaged. When a major earthquake hits an urban area, one of the most critical information for rescue operations is rapid and accurate assessment of building-collapse areas. From a study on 2003 Bam earthquake in Iran, interferometric coherence was proved useful for earthquake damage assessment (Fielding et al., 2005) when similar perpendicular baselines can be found for pre- and coseismic interferometric pairs and when there is little temporal and volume decorrelation. In this study we develop a new algorithm to create a more robust and accurate damage assessment map using interferometric coherence despite different interferometric baselines and with other decorrelation sources. We test the algorithm on a building block that recently underwent demolition, which is a proxy for building collapse due to earthquakes, for new construction in the City of Pasadena, California. The size of the building block is about 150 m E-W and 300 m N-S, and the demolition project started on April 23, 2007 and continued until January 22, 2008. After we process Japanese L-band ALOS PALSAR data with ROI_PAC, an interferometric coherence map that spans the demolition period is registered to a coherence map before the demolition, and the relative bias of the coherence values are removed, then a causality constraint is applied to enhance the change due to demolition. The results show clear change in coherence at the demolition site. We improve the signal-to-noise ratio of the coherence change at the demolition site from 17.3 (for simple difference) to 44.6 (with the new algorithm). The damage assessment map algorithm will become more useful with the emergence of InSAR missions with more frequent data acquisition, such as Sentinel-1 and DESDynI.

  6. Robust image modeling technique with a bioluminescence image segmentation application

    NASA Astrophysics Data System (ADS)

    Zhong, Jianghong; Wang, Ruiping; Tian, Jie

    2009-02-01

    A robust pattern classifier algorithm for the variable symmetric plane model, where the driving noise is a mixture of a Gaussian and an outlier process, is developed. The veracity and high-speed performance of the pattern recognition algorithm is proved. Bioluminescence tomography (BLT) has recently gained wide acceptance in the field of in vivo small animal molecular imaging. So that it is very important for BLT to how to acquire the highprecision region of interest in a bioluminescence image (BLI) in order to decrease loss of the customers because of inaccuracy in quantitative analysis. An algorithm in the mode is developed to improve operation speed, which estimates parameters and original image intensity simultaneously from the noise corrupted image derived from the BLT optical hardware system. The focus pixel value is obtained from the symmetric plane according to a more realistic assumption for the noise sequence in the restored image. The size of neighborhood is adaptive and small. What's more, the classifier function is base on the statistic features. If the qualifications for the classifier are satisfied, the focus pixel intensity is setup as the largest value in the neighborhood.Otherwise, it will be zeros.Finally,pseudo-color is added up to the result of the bioluminescence segmented image. The whole process has been implemented in our 2D BLT optical system platform and the model is proved.

  7. A Interferometric Approach to Suppression of Scattered Radiant Energy

    NASA Astrophysics Data System (ADS)

    Thompson, Christopher John Campbell

    The concept of using an interferometric process to reduce scattered light in optical systems has been examined from a physical optics viewpoint. An experiment is described which illustrates the basic concepts of a particular scheme addressing the important case of a telescope viewing a distant point object whose image is degraded by scattering from dust on the primary lens. A basic conceptual scheme is described, utilizing a modified Twyman-Green interferometer, which introduces a (pi) phase shift and a focal power difference between the arms. The interferometer is inserted into the optical train of an elementary telescope to null the scattered energy while preserving the image intensity associated with the distant point object, thereby enhancing the signal -to-noise ratio. The effect of this interferometer on the image of a distant point object is examined in detail. Computer techniques were used to solve Lommel function based series representations of the diffraction integral, and generate the intensity distributions which are presented as a series of iso-intensity contour maps. The results indicate that a distant point object could be reimaged successfully. Further analytic evaluations reveal specific operating conditions for the interferometer that optimize the peak intensity at the focal plane. A wavefront model was used to derive the radially dependent intensity distribution at the focal plane from the single on-axis scattering point. To evaluate the effectiveness of the scatter-nulling interferometric technique, an analytic expression for the gain in signal-to-noise ratio was developed, utilizing elementary models of a reimaging systems with and without the inclusion of a nulling interferometer. Gains up to a factor of 10('8) were observed with the assumption of a reasonable set of system parameters and for the limited set of conditions employed. Results imply that the interferometric approach could be successful and effective under restricted conditions

  8. Review of passive imaging polarimetry for remote sensing applications.

    PubMed

    Tyo, J Scott; Goldstein, Dennis L; Chenault, David B; Shaw, Joseph A

    2006-08-01

    Imaging polarimetry has emerged over the past three decades as a powerful tool to enhance the information available in a variety of remote sensing applications. We discuss the foundations of passive imaging polarimetry, the phenomenological reasons for designing a polarimetric sensor, and the primary architectures that have been exploited for developing imaging polarimeters. Considerations on imaging polarimeters such as calibration, optimization, and error performance are also discussed. We review many important sources and examples from the scientific literature.

  9. Novel multispectral imaging microscope with applications to biomedicine

    NASA Astrophysics Data System (ADS)

    Zeng, Libo; Wu, Qiongshui; Ke, Hengyu; Zheng, Hong; Hu, Yaojun; Ding, Yi

    2005-03-01

    This paper describes a novel multispectral imaging microscope that can simultaneously record both spectral and spatial information of a sample, which can take advantage of spatial image processing and spectroscopic analysis techniques. A Liquid Crystal Tunable Filter device is used for fast wavelength selection and a cooled two-dimensional monochrome CCD for image detection. In order to acquire images that are not so dependent on imaging devices, a clever CCD exposure time control and a software based spectral and spatial calibration process is performed to diminish the influence of illumination, optic ununiformity, CCD"s spectral response curve and optic throughput property. A set of multispectral image processing and analysis software package is developed, which covers not only general image processing and analysis functions, and also provides powerful analysis tools for multispectral image data, including multispectral image acquisition, illumination and system response calibration, spectral analysis and etc. The combination of spatial and spectral analysis makes it an ideal tool for the applications to biomedicine. In this paper, two applications in biomedicine are also presented. One is medical image segmentation. Using multispectral imaging techniques, a mass of experiments on both marrow bone and cervical cell images showed that our segmentation results are highly satisfactory while with low computational cost. Another is biological imaging spectroscopic analysis in the study of pollen grains in rice. The results showed that the transmittance analysis of multispectral pollen images can accurately identify the pollen abortion stage of male-sterile rice, and can easily distinguish a variety of male sterile cytoplasm.

  10. The use of multisensor images for Earth Science applications

    NASA Technical Reports Server (NTRS)

    Evans, D.; Stromberg, B.

    1983-01-01

    The use of more than one remote sensing technique is particularly important for Earth Science applications because of the compositional and textural information derivable from the images. The ability to simultaneously analyze images acquired by different sensors requires coregistration of the multisensor image data sets. In order to insure pixel to pixel registration in areas of high relief, images must be rectified to eliminate topographic distortions. Coregistered images can be analyzed using a variety of multidimensional techniques and the acquired knowledge of topographic effects in the images can be used in photogeologic interpretations.

  11. Interferometric focusing of guide-stars for direct wavefront sensing

    NASA Astrophysics Data System (ADS)

    Tao, Xiaodong; Dean, Ziah; Chien, Christopher; Azucena, Oscar; Kubby, Joel

    2013-03-01

    Optical microscopy allows noninvasive imaging of biological tissues at a subcellular level. However, the optimal performance of the microscope is hard to achieve because of aberrations induced from tissues. The shallow penetration depth and degraded resolution provide a limited degree of information for biologists. In order to compensate for aberrations, adaptive optics with direct wavefront sensing, where guide-stars are used for wavefront measurement, has been applied in microscopy. The scattering effect limits the intensity of a guide-star and hence reduces the signal to noise ratio of the wavefront measurement. In this paper, we propose to use interferometric focusing of excitation light onto a guide-star embedded deeply in tissue to increase its fluorescence intensity, thus overcoming the signal loss caused by scattering. With interferometric focusing of light, we increase the signal to noise ratio of the laser guide-star through scattering tissue by more than two times as well as potentially extending the thickness of tissue that can be corrected using AO microscopy.

  12. The flight test of Pi-SAR(L) for the repeat-pass interferometric SAR

    NASA Astrophysics Data System (ADS)

    Nohmi, Hitoshi; Shimada, Masanobu; Miyawaki, Masanori

    2006-09-01

    This paper describes the experiment of the repeat pass interferometric SAR using Pi-SAR(L). The air-borne repeat-pass interferometric SAR is expected as an effective method to detect landslide or predict a volcano eruption. To obtain a high-quality interferometric image, it is necessary to make two flights on the same flight pass. In addition, since the antenna of the Pi-SAR(L) is secured to the aircraft, it is necessary to fly at the same drift angle to keep the observation direction same. We built a flight control system using an auto pilot which has been installed in the airplane. This navigation system measures position and altitude precisely with using a differential GPS, and the PC Navigator outputs a difference from the desired course to the auto pilot. Since the air density is thinner and the speed is higher than the landing situation, the gain of the control system is required to be adjusted during the repeat pass flight. The observation direction could be controlled to some extent by adjusting a drift angle with using a flight speed control. The repeat-pass flight was conducted in Japan for three days in late November. The flight was stable and the deviation was within a few meters for both horizontal and vertical direction even in the gusty condition. The SAR data were processed in time domain based on range Doppler algorism to make the complete motion compensation. Thus, the interferometric image processed after precise phase compensation is shown.

  13. System for interferometric distortion measurements that define an optical path

    DOEpatents

    Bokor, Jeffrey; Naulleau, Patrick

    2003-05-06

    An improved phase-shifting point diffraction interferometer can measure both distortion and wavefront aberration. In the preferred embodiment, the interferometer employs an object-plane pinhole array comprising a plurality of object pinholes located between the test optic and the source of electromagnetic radiation and an image-plane mask array that is positioned in the image plane of the test optic. The image-plane mask array comprises a plurality of test windows and corresponding reference pinholes, wherein the positions of the plurality of pinholes in the object-plane pinhole array register with those of the plurality of test windows in image-plane mask array. Electromagnetic radiation that is directed into a first pinhole of object-plane pinhole array thereby creating a first corresponding test beam image on the image-plane mask array. Where distortion is relatively small, it can be directly measured interferometrically by measuring the separation distance between and the orientation of the test beam and reference-beam pinhole and repeating this process for at least one other pinhole of the plurality of pinholes of the object-plane pinhole array. Where the distortion is relative large, it can be measured by using interferometry to direct the stage motion, of a stage supporting the image-plane mask array, and then use the final stage motion as a measure of the distortion.

  14. A compact LWIR Fourier transform imaging spectrometer employing a variable gap Fabry-Perot interferometer

    NASA Astrophysics Data System (ADS)

    Zhang, Fang; Gao, Jiaobo; Liu, Fang; Zhao, Yujie; Zheng, Yawei; Zhang, Lei

    2016-10-01

    With unique working principle and spectral characteristic, the long wave infrared (LWIR) interferometric spectral imaging is a popular technology with wide application in many fields. In order to miniaturize and light the instrument, a new method of LWIR spectral imaging system based on a variable gap Fabry-Perot (FP) interferometer is researched. With the system working principle analyzed, theoretically, it is researched that how to make certain the primary parameter, such as, the reflectivity of the two interferometric cavity surfaces and the wedge angle of interferometric cavity. A prototype is developed and good experimental results of blackbody and polypropylene film are obtained. The research shows that besides high throughput and high spectral resolution, the advantage of miniaturization is also simultaneously achieved in this method.

  15. Colour application on mammography image segmentation

    NASA Astrophysics Data System (ADS)

    Embong, R.; Aziz, N. M. Nik Ab.; Karim, A. H. Abd; Ibrahim, M. R.

    2017-09-01

    The segmentation process is one of the most important steps in image processing and computer vision since it is vital in the initial stage of image analysis. Segmentation of medical images involves complex structures and it requires precise segmentation result which is necessary for clinical diagnosis such as the detection of tumour, oedema, and necrotic tissues. Since mammography images are grayscale, researchers are looking at the effect of colour in the segmentation process of medical images. Colour is known to play a significant role in the perception of object boundaries in non-medical colour images. Processing colour images require handling more data, hence providing a richer description of objects in the scene. Colour images contain ten percent (10%) additional edge information as compared to their grayscale counterparts. Nevertheless, edge detection in colour image is more challenging than grayscale image as colour space is considered as a vector space. In this study, we implemented red, green, yellow, and blue colour maps to grayscale mammography images with the purpose of testing the effect of colours on the segmentation of abnormality regions in the mammography images. We applied the segmentation process using the Fuzzy C-means algorithm and evaluated the percentage of average relative error of area for each colour type. The results showed that all segmentation with the colour map can be done successfully even for blurred and noisy images. Also the size of the area of the abnormality region is reduced when compare to the segmentation area without the colour map. The green colour map segmentation produced the smallest percentage of average relative error (10.009%) while yellow colour map segmentation gave the largest percentage of relative error (11.367%).

  16. Image analysis applications for grain science

    NASA Astrophysics Data System (ADS)

    Zayas, Inna Y.; Steele, James L.

    1991-02-01

    Morphometrical features of single grain kernels or particles were used to discriminate two visibly similar wheat varieties foreign material in wheat hardsoft and spring-winter wheat classes and whole from broken corn kernels. Milled fractions of hard and soft wheat were evaluated using textural image analysis. Color image analysis of sound and mold damaged corn kernels yielded high recognition rates. The studies collectively demonstrate the potential for automated classification and assessment of grain quality using image analysis.

  17. Infrared active polarimetric imaging system controlled by image segmentation algorithms: application to decamouflage

    NASA Astrophysics Data System (ADS)

    Vannier, Nicolas; Goudail, François; Plassart, Corentin; Boffety, Matthieu; Feneyrou, Patrick; Leviandier, Luc; Galland, Frédéric; Bertaux, Nicolas

    2016-05-01

    We describe an active polarimetric imager with laser illumination at 1.5 µm that can generate any illumination and analysis polarization state on the Poincar sphere. Thanks to its full polarization agility and to image analysis of the scene with an ultrafast active-contour based segmentation algorithm, it can perform adaptive polarimetric contrast optimization. We demonstrate the capacity of this imager to detect manufactured objects in different types of environments for such applications as decamouflage and hazardous object detection. We compare two imaging modes having different number of polarimetric degrees of freedom and underline the characteristics that a polarimetric imager aimed at this type of applications should possess.

  18. Image segmentation by iterative parallel region growing with application to data compression and image analysis

    NASA Technical Reports Server (NTRS)

    Tilton, James C.

    1988-01-01

    Image segmentation can be a key step in data compression and image analysis. However, the segmentation results produced by most previous approaches to region growing are suspect because they depend on the order in which portions of the image are processed. An iterative parallel segmentation algorithm avoids this problem by performing globally best merges first. Such a segmentation approach, and two implementations of the approach on NASA's Massively Parallel Processor (MPP) are described. Application of the segmentation approach to data compression and image analysis is then described, and results of such application are given for a LANDSAT Thematic Mapper image.

  19. Clinical applications of functional MR imaging.

    PubMed

    Belyaev, Artem S; Peck, Kyung K; Brennan, Nicole M Petrovich; Holodny, Andrei I

    2013-05-01

    Functional magnetic resonance (fMR) imaging for neurosurgical planning has become the standard of care in centers where it is available. Although paradigms to measure eloquent cortices are not yet standardized, simple tasks elicit reliable maps for planning neurosurgical procedures. A patient-specific paradigm design will refine the usability of fMR imaging for prognostication and recovery of function. Certain pathologic conditions and technical issues limit the interpretation of fMR imaging maps in clinical use and should be considered carefully. However, fMR imaging for neurosurgical planning continues to provide insights into how the brain works and how it responds to pathologic insults.

  20. A continuous available (CA) server for medical imaging applications.

    PubMed

    Huang, H K; Liu, Brent J; Zhou, Z

    2004-07-01

    The trend of medical imaging research and application is toward large database management and manipulation, which requires a robust image server to receive image data from sources and to deliver them to users reliably and in a timely fashion. This article describes the design, implementation, and clinical applications of a continuous available (CA) image server for these purposes. The design of the CA image server is based on the concept of a triple modular redundancy server with three redundant server modules. Coupled with a majority voting mechanism in the three modules and failover software, the triple modular redundancy server takes care of all single points of failure hardware components in the CA image server automatically to achieve fault tolerance. Methods and procedures of evaluating the fault tolerance system reliability caused by network connectivity, motherboard, and disk storage failures are described. Thorough experimental results in laboratory and clinical environments verify that the image server achieves 99.999% hardware up time (or 5 minutes/year down time), satisfying the industrial terminology of hardware continuous availability. Performance of failover of the CA image server is automatically tabulated during these procedures. Applications of CA image server are extensive. Two examples are given including Picture Archiving and Communication System, and off-site back-up archive using the Application Service Provider model. As designed, the CA image server is portable, scalable, affordable, easy to install, and requires no human intervention during failover and system recovery.

  1. Application of Stereo-Imaging Technology to Medical Field

    PubMed Central

    Nam, Kyoung Won; Park, Jeongyun; Kim, In Young

    2012-01-01

    Objectives There has been continuous development in the area of stereoscopic medical imaging devices, and many stereoscopic imaging devices have been realized and applied in the medical field. In this article, we review past and current trends pertaining to the application stereo-imaging technologies in the medical field. Methods We describe the basic principles of stereo vision and visual issues related to it, including visual discomfort, binocular disparities, vergence-accommodation mismatch, and visual fatigue. We also present a brief history of medical applications of stereo-imaging techniques, examples of recently developed stereoscopic medical devices, and patent application trends as they pertain to stereo-imaging medical devices. Results Three-dimensional (3D) stereo-imaging technology can provide more realistic depth perception to the viewer than conventional two-dimensional imaging technology. Therefore, it allows for a more accurate understanding and analysis of the morphology of an object. Based on these advantages, the significance of stereoscopic imaging in the medical field increases in accordance with the increase in the number of laparoscopic surgeries, and stereo-imaging technology plays a key role in the diagnoses of the detailed morphologies of small biological specimens. Conclusions The application of 3D stereo-imaging technology to the medical field will help improve surgical accuracy, reduce operation times, and enhance patient safety. Therefore, it is important to develop more enhanced stereoscopic medical devices. PMID:23115737

  2. Application of stereo-imaging technology to medical field.

    PubMed

    Nam, Kyoung Won; Park, Jeongyun; Kim, In Young; Kim, Kwang Gi

    2012-09-01

    There has been continuous development in the area of stereoscopic medical imaging devices, and many stereoscopic imaging devices have been realized and applied in the medical field. In this article, we review past and current trends pertaining to the application stereo-imaging technologies in the medical field. We describe the basic principles of stereo vision and visual issues related to it, including visual discomfort, binocular disparities, vergence-accommodation mismatch, and visual fatigue. We also present a brief history of medical applications of stereo-imaging techniques, examples of recently developed stereoscopic medical devices, and patent application trends as they pertain to stereo-imaging medical devices. Three-dimensional (3D) stereo-imaging technology can provide more realistic depth perception to the viewer than conventional two-dimensional imaging technology. Therefore, it allows for a more accurate understanding and analysis of the morphology of an object. Based on these advantages, the significance of stereoscopic imaging in the medical field increases in accordance with the increase in the number of laparoscopic surgeries, and stereo-imaging technology plays a key role in the diagnoses of the detailed morphologies of small biological specimens. The application of 3D stereo-imaging technology to the medical field will help improve surgical accuracy, reduce operation times, and enhance patient safety. Therefore, it is important to develop more enhanced stereoscopic medical devices.

  3. BOOK REVIEW: Infrared Thermal Imaging: Fundamentals, Research and Applications Infrared Thermal Imaging: Fundamentals, Research and Applications

    NASA Astrophysics Data System (ADS)

    Planinsic, Gorazd

    2011-09-01

    Ten years ago, a book with a title like this would be interesting only to a narrow circle of specialists. Thanks to rapid advances in technology, the price of thermal imaging devices has dropped sharply, so they have, almost overnight, become accessible to a wide range of users. As the authors point out in the preface, the growth of this area has led to a paradoxical situation: now there are probably more infrared (IR) cameras sold worldwide than there are people who understand the basic physics behind them and know how to correctly interpret the colourful images that are obtained with these devices. My experience confirms this. When I started using the IR camera during lectures on the didactics of physics, I soon realized that I needed more knowledge, which I later found in this book. A wide range of potential readers and topical areas provides a good motive for writing a book such as this one, but it also represents a major challenge for authors, as compromises in the style of writing and choice of topics are required. The authors of this book have successfully achieved this, and indeed done an excellent job. This book addresses a wide range of readers, from engineers, technicians, and physics and science teachers in schools and universities, to researchers and specialists who are professionally active in the field. As technology in this area has made great progress in recent times, this book is also a valuable guide for those who opt to purchase an infrared camera. Chapters in this book could be divided into three areas: the fundamentals of IR thermal imaging and related physics (two chapters); IR imaging systems and methods (two chapters) and applications, including six chapters on pedagogical applications; IR imaging of buildings and infrastructure, industrial applications, microsystems, selected topics in research and industry, and selected applications from other fields. All chapters contain numerous colour pictures and diagrams, and a rich list of relevant

  4. Novel biomedical applications of Cerenkov radiation and radioluminescence imaging.

    PubMed

    Spinelli, Antonello E; Boschi, Federico

    2015-03-01

    The main goals of this review is to provide an up-to-date account of the different uses of Cerenkov radiation (CR) and radioluminescence imaging for pre-clinical small animal imaging. We will focus on new emerging applications such as the use of Cerenkov imaging for monitoring radionuclide and external radiotherapy in humans. Another novel application that will be described is the monitoring of radiochemical synthesis using microfluidic chips. Several pre-clinical aspects of CR will be discussed such as the development of 3D reconstruction methods for Cerenkov images and the use of CR as excitation source for nanoparticles or for endoscopic imaging. We will also include a discussion on radioluminescence imaging that is a more general method than Cerenkov imaging for the detection using optical methods of alpha and gamma emitters.

  5. Merging of range images for inspection or safety applications

    NASA Astrophysics Data System (ADS)

    Mure-Dubois, James; Hügli, Heinz

    2008-08-01

    Range imagers provide useful information for part inspection, robot control, or human safety applications in industrial environments. However, some applications may require more information than range data from a single viewpoint. Therefore, multiple range images must be combined to create a three-dimensional representation of the scene. Although simple in its principle, this operation is not straightforward to implement in industrial systems, since each range image is affected by noise. In this paper, we present two specific applications where merging of range images must be performed. We use the same processing pipeline for both applications : conversion from range image to point clouds, elimination of degrees of freedom between different clouds, validation of the merged results. Nevertheless, each step in this pipeline requires dedicated algorithms for our example applications. The first application is high resolution inspection of large parts, where many range images are acquired sequentially and merged in a post-processing step, allowing to create a virtual model of the part observed, typically larger than the instrument's field of view. The key requirement in this application is high accuracy for the merging of multiple point clouds. The second application discussed is human safety in a human/robot environment: range images are used to ensure that no human is present in the robot’s zone of operation, and can trigger the robot's emergency shutdown when needed. In this case, range image merging is required to avoid uncertainties due to occlusions. The key requirement here is real-time operation, namely the merging operation should not introduce a significant latency in the data processing pipeline. For both application cases, the improvements brought by merging multiple range images are clearly illustrated.

  6. Novel compact photoacoustic imaging system to explore the applications in the medical imaging field

    NASA Astrophysics Data System (ADS)

    Irisawa, Kaku; Wada, Takatsugu; Hayakawa, Toshiro; Ishihara, Miya

    2017-04-01

    PhotoAcoustic (PA) imaging is a promising imaging method using the pulsed-laser light source and ultrasound detector. PA image shows the features of optical contrast in biological tissue with ultrasound-like depth and resolution. In the human body, Hemoglobin of the blood is strong optical absorber, so the high-contrast blood distribution (vascular) image is obtained by PA imaging. Recently, FUJIFILM has developed the PA imaging system to explore its application in medical imaging field. In this system, the fusion of PA and conventional ultrasound image is realized, for example, ultrasound Doppler image is superposed to the PA and B-mode image. The system features and some results of clinical studies will be introduced.

  7. Nonlinear Optical Image Subtraction For Potential Industrial Applications

    NASA Astrophysics Data System (ADS)

    Chiou, Arthur E.; Yeh, Pochi; Khoshnevisan, Monte

    1988-05-01

    Recent advances in optical phase conjugation and energy coupling at optical powers as low as a few milliwatts have added a new dimension to optical image processing. Conventional image processing techniques based on convolution/correlation, matched filtering, and holographic interferometry can now be achieved with much simpler components and usually at much higher efficiency by incorporating these new features. Some of the application concepts that had been impracticable can now be realized. The basic principle and potential industrial applications of real-time image subtraction using dynamic holograms are reviewed. Optical implementations and experimental results on image subtraction, novelty filtering, and defect detection are discussed.

  8. Measuring the Direction and Angular Velocity of a Black Hole Accretion Disk via Lagged Interferometric Covariance

    NASA Astrophysics Data System (ADS)

    Johnson, Michael D.; Loeb, Abraham; Shiokawa, Hotaka; Chael, Andrew A.; Doeleman, Sheperd S.

    2015-11-01

    We show that interferometry can be applied to study irregular, rapidly rotating structures, as are expected in the turbulent accretion flow near a black hole. Specifically, we analyze the lagged covariance between interferometric baselines of similar lengths but slightly different orientations. For a flow viewed close to face-on, we demonstrate that the peak in the lagged covariance indicates the direction and angular velocity of the emission pattern from the flow. Even for moderately inclined flows, the covariance robustly estimates the flow direction, although the estimated angular velocity can be significantly biased. Importantly, measuring the direction of the flow as clockwise or counterclockwise on the sky breaks a degeneracy in accretion disk inclinations when analyzing time-averaged images alone. We explore the potential efficacy of our technique using three-dimensional, general relativistic magnetohydrodynamic simulations, and we highlight several baseline pairs for the Event Horizon Telescope (EHT) that are well-suited to this application. These results indicate that the EHT may be capable of estimating the direction and angular velocity of the emitting material near Sgr A*, and they suggest that a rotating flow may even be utilized to improve imaging capabilities.

  9. MEASURING THE DIRECTION AND ANGULAR VELOCITY OF A BLACK HOLE ACCRETION DISK VIA LAGGED INTERFEROMETRIC COVARIANCE

    SciTech Connect

    Johnson, Michael D.; Loeb, Abraham; Shiokawa, Hotaka; Chael, Andrew A.; Doeleman, Sheperd S.

    2015-11-10

    We show that interferometry can be applied to study irregular, rapidly rotating structures, as are expected in the turbulent accretion flow near a black hole. Specifically, we analyze the lagged covariance between interferometric baselines of similar lengths but slightly different orientations. For a flow viewed close to face-on, we demonstrate that the peak in the lagged covariance indicates the direction and angular velocity of the emission pattern from the flow. Even for moderately inclined flows, the covariance robustly estimates the flow direction, although the estimated angular velocity can be significantly biased. Importantly, measuring the direction of the flow as clockwise or counterclockwise on the sky breaks a degeneracy in accretion disk inclinations when analyzing time-averaged images alone. We explore the potential efficacy of our technique using three-dimensional, general relativistic magnetohydrodynamic simulations, and we highlight several baseline pairs for the Event Horizon Telescope (EHT) that are well-suited to this application. These results indicate that the EHT may be capable of estimating the direction and angular velocity of the emitting material near Sgr A*, and they suggest that a rotating flow may even be utilized to improve imaging capabilities.

  10. Photoacoustic tomography: applications for atherosclerosis imaging

    NASA Astrophysics Data System (ADS)

    Sangha, Gurneet S.; Goergen, Craig J.

    2016-08-01

    Atherosclerosis is a debilitating condition that increases a patient’s risk for intermittent claudication, limb amputation, myocardial infarction, and stroke, thereby causing approximately 50% of deaths in the western world. Current diagnostic imaging techniques, such as ultrasound, digital subtraction angiography, computed tomography angiography, magnetic resonance angiography, and optical imaging remain suboptimal for detecting development of early stage plaques. This is largely due to the lack of compositional information, penetration depth, and/or clinical efficiency of these traditional imaging techniques. Photoacoustic imaging has emerged as a promising modality that could address some of these limitations to improve the diagnosis and characterization of atherosclerosis-related diseases. Photoacoustic imaging uses near-infrared light to induce acoustic waves, which can be used to recreate compositional images of tissue. Recent developments in photoacoustic techniques show its potential in noninvasively characterizing atherosclerotic plaques deeper than traditional optical imaging approaches. In this review, we discuss the significance and development of atherosclerosis, current and novel clinical diagnostic methods, and recent works that highlight the potential of photoacoustic imaging for both experimental and clinical studies of atherosclerosis.

  11. Imaging-Genetics Applications in Child Psychiatry

    ERIC Educational Resources Information Center

    Pine, Daniel S.; Ernst, Monique; Leibenluft, Ellen

    2010-01-01

    Objective: To place imaging-genetics research in the context of child psychiatry. Method: A conceptual overview is provided, followed by discussion of specific research examples. Results: Imaging-genetics research is described linking brain function to two specific genes, for the serotonin-reuptake-transporter protein and a monoamine oxidase…

  12. Some applications of the imaging proportional chamber

    NASA Astrophysics Data System (ADS)

    Charpak, G.; Dominik, W.; Fabre, J. P.; Gaudaen, J.; Peskov, V.

    1988-02-01

    Photons emitted by avalanches in gases can be detected with an image intensifier coupled to a solid-state camera. Some vapors enhance the emission at wavelengths close to the visible. Progress made in using this technique to image charged particles and Cherenkov photons is described. Results are presented for various gas mixtures containing TEA and TMAE.

  13. Imaging-Genetics Applications in Child Psychiatry

    ERIC Educational Resources Information Center

    Pine, Daniel S.; Ernst, Monique; Leibenluft, Ellen

    2010-01-01

    Objective: To place imaging-genetics research in the context of child psychiatry. Method: A conceptual overview is provided, followed by discussion of specific research examples. Results: Imaging-genetics research is described linking brain function to two specific genes, for the serotonin-reuptake-transporter protein and a monoamine oxidase…

  14. Application of coherent 10 micron imaging lidar

    SciTech Connect

    Simpson, M.L.; Hutchinson, D.P.; Richards, R.K.; Bennett, C.A.

    1997-04-01

    With the continuing progress in mid-IR array detector technology and high bandwidth fan-outs, i.f. electronics, high speed digitizers, and processing capability, true coherent imaging lidar is becoming a reality. In this paper experimental results are described using a 10 micron coherent imaging lidar.

  15. Application of image recognition in GIS

    NASA Astrophysics Data System (ADS)

    Xu, Kaiyu; Xu, Zhijing; Zheng, Huayao

    2003-09-01

    In view of the existing issues on extraction of GIS vector data from maps, we propose an image recognition method based on wavelet transformation. Using the method, we first made the wavelet transformation of a color urban traffic map and took the value near zero points of the wavelet coefficient, and then, color model transformation was adopted to obtain a gray image. Afterwards, an appropriate threshold was chosen and the gray image was transformed into a bilevel image. In the end, the erosion algorithm in the mathematical morphology was used to thin the image in order to identify the road information. The experimental result showed that the method could be used to effectively identify the road information from an urban traffic map.

  16. Interferometric synthetic aperture radar: Building tomorrow's tools today

    USGS Publications Warehouse

    Lu, Zhong

    2006-01-01

    A synthetic aperture radar (SAR) system transmits electromagnetic (EM) waves at a wavelength that can range from a few millimeters to tens of centimeters. The radar wave propagates through the atmosphere and interacts with the Earth’s surface. Part of the energy is reflected back to the SAR system and recorded. Using a sophisticated image processing technique, called SAR processing (Curlander and McDonough, 1991), both the intensity and phase of the reflected (or backscattered) signal of each ground resolution element (a few meters to tens of meters) can be calculated in the form of a complex-valued SAR image representing the reflectivity of the ground surface. The amplitude or intensity of the SAR image is determined primarily by terrain slope, surface roughness, and dielectric constants, whereas the phase of the SAR image is determined primarily by the distance between the satellite antenna and the ground targets, slowing of the signal by the atmosphere, and the interaction of EM waves with ground surface. Interferometric SAR (InSAR) imaging, a recently developed remote sensing technique, utilizes the interaction of EM waves, referred to as interference, to measure precise distances. Very simply, InSAR involves the use of two or more SAR images of the same area to extract landscape topography and its deformation patterns.

  17. Interferometric estimation of ice sheet motion and topography

    NASA Technical Reports Server (NTRS)

    Joughlin, Ian; Kwok, Ron; Fahnestock, Mark; Winebrenner, Dale; Tulaczyk, Slawek; Gogenini, Prasad

    1997-01-01

    With ERS-1/2 satellite radar interferometry, it is possible to make measurements of glacier motion with high accuracy and fine spatial resolution. Interferometric techniques were applied to map velocity and topography for several outlet glaciers in Greenland. For the Humboldt and Petermann glaciers, data from several adjacent tracks were combined to make a wide-area map that includes the enhanced flow regions of both glaciers. The discharge flux of the Petermann glacier upstream of the grounding line was estimated, thereby establishing the potential use of ERS-1/2 interferometric data for monitoring ice-sheet discharge. Interferograms collected along a single track are sensitive to only one component of motion. By utilizing data from ascending and descending passes and by making a surface-parallel flow assumption, it is possible to measure the full three-dimensional vector flow field. The application of this technique for an area on the Ryder glacier is demonstrated. Finally, ERS-1/2 interferograms were used to observe a mini-surge on the Ryder glacier that occurred in autumn of 1995.

  18. Interferometric estimation of ice sheet motion and topography

    NASA Technical Reports Server (NTRS)

    Joughlin, Ian; Kwok, Ron; Fahnestock, Mark; Winebrenner, Dale; Tulaczyk, Slawek; Gogenini, Prasad

    1997-01-01

    With ERS-1/2 satellite radar interferometry, it is possible to make measurements of glacier motion with high accuracy and fine spatial resolution. Interferometric techniques were applied to map velocity and topography for several outlet glaciers in Greenland. For the Humboldt and Petermann glaciers, data from several adjacent tracks were combined to make a wide-area map that includes the enhanced flow regions of both glaciers. The discharge flux of the Petermann glacier upstream of the grounding line was estimated, thereby establishing the potential use of ERS-1/2 interferometric data for monitoring ice-sheet discharge. Interferograms collected along a single track are sensitive to only one component of motion. By utilizing data from ascending and descending passes and by making a surface-parallel flow assumption, it is possible to measure the full three-dimensional vector flow field. The application of this technique for an area on the Ryder glacier is demonstrated. Finally, ERS-1/2 interferograms were used to observe a mini-surge on the Ryder glacier that occurred in autumn of 1995.

  19. Interferometric Views of Star Formation

    NASA Astrophysics Data System (ADS)

    Plambeck, R. L.; Wright, M. C. H.

    1999-10-01

    Many studies of molecular clouds require quantitative comparisons of images at widely different wavelengths. For example, one may map dust spectral index variations to search for evidence of grain growth in protostellar cores, or use 3-2/2-1/1-0 C18O line ratios to derive gas kinetic temperatures, or search for chemical abundance anomalies caused by shocks or MHD waves. ALMA will dramatically improve the accuracy of these measurements because it will provide almost complete sampling of visibilities across the u,v plane, allowing one to synthesize mathematically perfect, matched beams at different wavelengths. The reliability of such comparisons will be limited by the difficulty in measuring the flux from extended structures. For a homogeneous array such as ALMA, visibilities on spacings smaller than the antenna diameter are recovered by mosaicing. Pointing and surface errors lead to errors in these data, limiting the image fidelity (Cornwell, Holdaway, & Uson 1993), particularly at submillimeter wavelengths. One could improve the image fidelity by measuring the short spacing visibilities directly with an auxiliary array of smaller antennas.

  20. Image acquisition system for traffic monitoring applications

    NASA Astrophysics Data System (ADS)

    Auty, Glen; Corke, Peter I.; Dunn, Paul; Jensen, Murray; Macintyre, Ian B.; Mills, Dennis C.; Nguyen, Hao; Simons, Ben

    1995-03-01

    An imaging system for monitoring traffic on multilane highways is discussed. The system, named Safe-T-Cam, is capable of operating 24 hours per day in all but extreme weather conditions and can capture still images of vehicles traveling up to 160 km/hr. Systems operating at different remote locations are networked to allow transmission of images and data to a control center. A remote site facility comprises a vehicle detection and classification module (VCDM), an image acquisition module (IAM) and a license plate recognition module (LPRM). The remote site is connected to the central site by an ISDN communications network. The remote site system is discussed in this paper. The VCDM consists of a video camera, a specialized exposure control unit to maintain consistent image characteristics, and a 'real-time' image processing system that processes 50 images per second. The VCDM can detect and classify vehicles (e.g. cars from trucks). The vehicle class is used to determine what data should be recorded. The VCDM uses a vehicle tracking technique to allow optimum triggering of the high resolution camera of the IAM. The IAM camera combines the features necessary to operate consistently in the harsh environment encountered when imaging a vehicle 'head-on' in both day and night conditions. The image clarity obtained is ideally suited for automatic location and recognition of the vehicle license plate. This paper discusses the camera geometry, sensor characteristics and the image processing methods which permit consistent vehicle segmentation from a cluttered background allowing object oriented pattern recognition to be used for vehicle classification. The image capture of high resolution images and the image characteristics required for the LPRMs automatic reading of vehicle license plates, is also discussed. The results of field tests presented demonstrate that the vision based Safe-T-Cam system, currently installed on open highways, is capable of producing automatic

  1. Algorithms and Array Design Criteria for Robust Imaging in Interferometry

    DTIC Science & Technology

    2016-04-01

    of a pattern family popular in the literature . The end result of this set of analysis is, to the best of our knowledge, the first sufficient condition...scenes which closely match its point- source-collection assumption. The astronomical community has hence been led to consider more generally- applicable ...a compact image intensity. This kind of joint metric has been suggested for optical interferometric applications before in the work of Thiébaut (2013

  2. Dynamics of laser interferometric gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    Rakhmanov, Malik

    2000-11-01

    Dynamics of fields and mirrors in the new laser interferometric gravitational wave detectors is described. The dynamics of fields is formulated in terms of difference equations, which take into account the large delay due to the light transit time in the interferometer arm cavities. Solutions of these field equations are found in both transient and steady-state regimes. The solutions for fields in the transient regime can be used for the measurement of the parameters of Fabry-Perot cavities. The solutions for fields in the steady-state regime can be used for the analysis of noise performance of Fabry-Perot cavities. The dynamics of the mirrors is described in terms of two normal coordinates: the cavity length and its center of mass. Such dynamics is strongly affected by the radiation pressure of light circulating in the cavity. The forces of radiation pressure are nonlinear and nonconservative. These two effects introduce instabilities and give rise to a violation of conservation of energy for the motion of the suspended mirrors. Analytical calculations and numerical simulations of the dynamics are done with applications to the Laser Interferometer Gravitational-Wave Observatory (LIGO). The dynamics of signal recycling and power recycling interferometers is analyzed using the field equations. The response of the interferometers to the input laser field and motion of its mirrors is calculated. Several basic transfer functions are found. These correspond to either a single or a nested cavity. A nested cavity appears either in the dynamics of the differential mode in signal recycling interferometers or in the dynamics of the common mode of power recycling interferometers. The poles of transfer functions of these nested cavities are found. The response of the interferometers to gravitational waves is described: the analysis is done in the rest frame of a local observer which is a natural coordinate system of the detector. This response is given by the interferometer

  3. Application of ASAP in integral imaging

    NASA Astrophysics Data System (ADS)

    Wang, Hong-xia; Xu, Zhi-li; Wen, Shao-jie; Wu, Chun-hong

    2012-10-01

    Integral imaging (II) is a technique that is capable of displaying 3D images with continuous parallax in full natural color. At present Integral Imaging is a popular three-dimensional imaging technology. It is becoming the most perspective technique in developing next generation three-dimensional TV (3DTV) and visualization field due to its outstanding advantages. The micro-lens array is used in recording and replaying 3D scene information in this technique with true color, simply reconstruction and non-relevant light source. In order to research really many precision instrument are required. But the price is too high to set up a complicated authentic imaging system. In the same time the imaging condition is very difficult to satisfy. ASAP (Advanced System Analysis Program) is an advanced imitates optical software to solve reality optical questions. It is used in many research territories. In this paper the ASAP software is proposed to simulate and model the micro-lens array sheet. The ray tracing and energy distribution is completed. According to the study results we can optimum lens designing through modifying the focal length, aperture size and imaging position. We hope the study cost can be reduced and the efficiency can be improved through the use of simulation method to optical design software ASAP.

  4. TM Digital Image Products for Applications

    NASA Technical Reports Server (NTRS)

    Barker, J. L.; Gunther, F. J.; Abrams, R. B.; Ball, D. L.

    1984-01-01

    LANDSAT-4 Thematic Mapper (TM) digital image products recorded onto computer compatible tapes (CCTs), which were available for internal research purposes prior to August, 1983, are reviewed. The SCROUNGE image processing system at Goddard Space Flight Centr generated in tape formats: (1) raw band-sequential data (CCT-BT), generally used for internal transportation of digital data from one ground processing system to another; (2) calibrated data (CCT-AT), useful for reseachers doing radiometric characterization; and (3) geometrically resampled data (CCT-PT), the final product. The formats represent different steps in the process of producing fully-corrected TM data. The CCT-BT images are re-sequenced from telemetry format to image format, but are uncorrected radiometrically and geometrically. The CCT-AT images had data from two faulty data channels replaced and all data radiometrically calibrated. The CCT-PT images were resampled by cubic convolution procedures to provide a geometrically corrected image using satellite ephemeris and altitude data and scan-mirror correction data. The final product, the CCT-PT, is the one to which all of the radiometric and geometric corrections were applied.

  5. Geophysical subsurface imaging for ecological applications.

    PubMed

    Jayawickreme, Dushmantha H; Jobbágy, Esteban G; Jackson, Robert B

    2014-03-01

    Ecologists, ecohydrologists, and biogeochemists need detailed insights into belowground properties and processes, including changes in water, salts, and other elements that can influence ecosystem productivity and functioning. Relying on traditional sampling and observation techniques for such insights can be costly, time consuming, and infeasible, especially if the spatial scales involved are large. Geophysical imaging provides an alternative or complement to traditional methods to gather subsurface variables across time and space. In this paper, we review aspects of geophysical imaging, particularly electrical and electromagnetic imaging, that may benefit ecologists seeking clearer understanding of the shallow subsurface. Using electrical resistivity imaging, for example, we have been able to successfully show the effect of land-use conversions to agriculture on salt mobilization and leaching across kilometer-long transects and to depths of tens of meters. Recent advances in ground-penetrating radar and other geophysical imaging methods currently provide opportunities for subsurface imaging with sufficient detail to locate small (≥5 cm diameter) animal burrows and plant roots, observe soil-water and vegetation spatial correlations in small watersheds, estuaries, and marshes, and quantify changes in groundwater storage at local to regional scales using geophysical data from ground- and space-based platforms. Ecologists should benefit from adopting these minimally invasive, scalable imaging technologies to explore the subsurface and advance our collective research.

  6. Retinal image analysis: concepts, applications and potential.

    PubMed

    Patton, Niall; Aslam, Tariq M; MacGillivray, Thomas; Deary, Ian J; Dhillon, Baljean; Eikelboom, Robert H; Yogesan, Kanagasingam; Constable, Ian J

    2006-01-01

    As digital imaging and computing power increasingly develop, so too does the potential to use these technologies in ophthalmology. Image processing, analysis and computer vision techniques are increasing in prominence in all fields of medical science, and are especially pertinent to modern ophthalmology, as it is heavily dependent on visually oriented signs. The retinal microvasculature is unique in that it is the only part of the human circulation that can be directly visualised non-invasively in vivo, readily photographed and subject to digital image analysis. Exciting developments in image processing relevant to ophthalmology over the past 15 years includes the progress being made towards developing automated diagnostic systems for conditions, such as diabetic retinopathy, age-related macular degeneration and retinopathy of prematurity. These diagnostic systems offer the potential to be used in large-scale screening programs, with the potential for significant resource savings, as well as being free from observer bias and fatigue. In addition, quantitative measurements of retinal vascular topography using digital image analysis from retinal photography have been used as research tools to better understand the relationship between the retinal microvasculature and cardiovascular disease. Furthermore, advances in electronic media transmission increase the relevance of using image processing in 'teleophthalmology' as an aid in clinical decision-making, with particular relevance to large rural-based communities. In this review, we outline the principles upon which retinal digital image analysis is based. We discuss current techniques used to automatically detect landmark features of the fundus, such as the optic disc, fovea and blood vessels. We review the use of image analysis in the automated diagnosis of pathology (with particular reference to diabetic retinopathy). We also review its role in defining and performing quantitative measurements of vascular topography

  7. Mathematical Morphology Techniques For Image Processing Applications In Biomedical Imaging

    NASA Astrophysics Data System (ADS)

    Bartoo, Grace T.; Kim, Yongmin; Haralick, Robert M.; Nochlin, David; Sumi, Shuzo M.

    1988-06-01

    Mathematical morphology operations allow object identification based on shape and are useful for grouping a cluster of small objects into one object. Because of these capabilities, we have implemented and evaluated this technique for our study of Alzheimer's disease. The microscopic hallmark of Alzheimer's disease is the presence of brain lesions known as neurofibrillary tangles and senile plaques. These lesions have distinct shapes compared to normal brain tissue. Neurofibrillary tangles appear as flame-shaped structures, whereas senile plaques appear as circular clusters of small objects. In order to quantitatively analyze the distribution of these lesions, we have developed and applied the tools of mathematical morphology on the Pixar Image Computer. As a preliminary test of the accuracy of the automatic detection algorithm, a study comparing computer and human detection of senile plaques was performed by evaluating 50 images from 5 different patients. The results of this comparison demonstrates that the computer counts correlate very well with the human counts (correlation coefficient = .81). Now that the basic algorithm has been shown to work, optimization of the software will be performed to improve its speed. Also future improvements such as local adaptive thresholding will be made to the image analysis routine to further improve the systems accuracy.

  8. Optical and digital microscopic imaging techniques and applications in pathology.

    PubMed

    Chen, Xiaodong; Zheng, Bin; Liu, Hong

    2011-01-01

    The conventional optical microscope has been the primary tool in assisting pathological examinations. The modern digital pathology combines the power of microscopy, electronic detection, and computerized analysis. It enables cellular-, molecular-, and genetic-imaging at high efficiency and accuracy to facilitate clinical screening and diagnosis. This paper first reviews the fundamental concepts of microscopic imaging and introduces the technical features and associated clinical applications of optical microscopes, electron microscopes, scanning tunnel microscopes, and fluorescence microscopes. The interface of microscopy with digital image acquisition methods is discussed. The recent developments and future perspectives of contemporary microscopic imaging techniques such as three-dimensional and in vivo imaging are analyzed for their clinical potentials.

  9. Laser applications and system considerations in ocular imaging

    PubMed Central

    Elsner, Ann E.; Muller, Matthew S.

    2009-01-01

    We review laser applications for primarily in vivo ocular imaging techniques, describing their constraints based on biological tissue properties, safety, and the performance of the imaging system. We discuss the need for cost effective sources with practical wavelength tuning capabilities for spectral studies. Techniques to probe the pathological changes of layers beneath the highly scattering retina and diagnose the onset of various eye diseases are described. The recent development of several optical coherence tomography based systems for functional ocular imaging is reviewed, as well as linear and nonlinear ocular imaging techniques performed with ultrafast lasers, emphasizing recent source developments and methods to enhance imaging contrast. PMID:21052482

  10. From atom to brain: applications of molecular imaging to neurosurgery.

    PubMed

    Taghva, Alexander; Khalessi, Alexander A; Kim, Paul E; Liu, Charles Y; Apuzzo, Michael L J

    2010-05-01

    Molecular imaging is a field born out of the happy marriage of molecular biology and radiology. The first installment of this two-part series on molecular imaging demonstrated basic principles for practitioners in the field of the neurosciences. This installment seeks to provide some illustrative examples, insights, and specific applications to the neurosciences. The fields of functional neurosurgery including the treatment of neuropsychiatric disorders, novel treatments and imaging of tumors, neuroregenerative medicine, and nanotechnology in vascular disorders are covered. Finally, we give some parting thoughts on the future of molecular imaging, including advances in the imaging of neurodegenerative disorders. Published by Elsevier Inc.

  11. Rehabilitative ultrasound imaging: understanding the technology and its applications.

    PubMed

    Whittaker, Jackie L; Teyhen, Deydre S; Elliott, James M; Cook, Katy; Langevin, Helene M; Dahl, Haldis H; Stokes, Maria

    2007-08-01

    The use of ultrasound imaging by physical therapists is growing in popularity. This commentary has 2 aims. The first is to introduce the concept of rehabilitative ultrasound imaging (RUSI), provide a definition of the scope of this emerging tool in regard to the physical therapy profession, and describe how this relates to the larger field of medical ultrasound imaging. The second aim is to provide an overview of basic ultrasound imaging and instrumentation principles, including an understanding of the various modes and applications of the technology with respect to neuromusculoskeletal rehabilitation and in relation to other common imaging modalities.

  12. In vivo Coherent Raman Imaging for Neuroscience Applications

    NASA Astrophysics Data System (ADS)

    Cote, Daniel

    2010-08-01

    The use of coherent Raman imaging is described for applications in neuroscience. Myelin imaging of the spinal cord can be performed with Raman imaging through the use of the vibration in carbon-hydrogen bonds, dominant in lipids. First, we demonstrate in vivo histomorphometry in live animal for characterization of myelin-related nervous system pathologies. This is used to characterize spinal cord health during multiple sclerosis. Second, Raman spectroscopy of tissue is discussed. We discuss the challenges that live animal imaging brings, together with important aspects of coherent Raman imaging in tissue.

  13. Application of optical coherence tomography based microangiography for cerebral imaging

    NASA Astrophysics Data System (ADS)

    Baran, Utku; Wang, Ruikang K.

    2016-03-01

    Requirements of in vivo rodent brain imaging are hard to satisfy using traditional technologies such as magnetic resonance imaging and two-photon microscopy. Optical coherence tomography (OCT) is an emerging tool that can easily reach at high speeds and provide high resolution volumetric images with a relatively large field of view for rodent brain imaging. Here, we provide the overview of recent developments of functional OCT based imaging techniques for neuroscience applications on rodents. Moreover, a summary of OCT-based microangiography (OMAG) studies for stroke and traumatic brain injury cases on rodents are provided.

  14. Uncooled thermal imaging sensor and application advances

    NASA Astrophysics Data System (ADS)

    Norton, Peter W.; Cox, Stephen; Murphy, Bob; Grealish, Kevin; Joswick, Mike; Denley, Brian; Feda, Frank; Elmali, Loriann; Kohin, Margaret

    2006-05-01

    BAE Systems continues to advance the technology and performance of microbolometer-based thermal imaging modules and systems. 640x480 digital uncooled infrared focal plane arrays are in full production, illustrated by recent production line test data for two thousand focal plane arrays. This paper presents a snapshot of microbolometer technology at BAE Systems and an overview of two of the most important thermal imaging sensor programs currently in production: a family of thermal weapons sights for the United States Army and a thermal imager for the remote weapons station on the Stryker vehicle.

  15. Applications of digital image processing IX

    SciTech Connect

    Tescher, A.G.

    1986-01-01

    This book contains the proceedings of SPIE - The International Society for Optical Engineering. The first session covers image compression and includes papers such as ''Knowledge-based image bandwidth compression.'' Session two is about instrumentation such as ''Real-time inspection of currency'' and ''Experimental digital image processor.'' Session three discusses theoretical concepts such as ''Study of texture segmentation.'' Session four is about algorithms. One such topic is ''Dynamic ordered dither algorithm.'' Session five covers registration and modeling. For example, one paper is ''3D-motion estimation from projections.'' Session six is about restoration and enhancement. Papers include ''Wobble error correction for laser scanners'' and ''Robotics with computer Vision.''

  16. Multimodality Image Fusion-Guided Procedures: Technique, Accuracy, and Applications

    SciTech Connect

    Abi-Jaoudeh, Nadine; Kruecker, Jochen; Kadoury, Samuel; Kobeiter, Hicham; Venkatesan, Aradhana M. Levy, Elliot Wood, Bradford J.

    2012-10-15

    Personalized therapies play an increasingly critical role in cancer care: Image guidance with multimodality image fusion facilitates the targeting of specific tissue for tissue characterization and plays a role in drug discovery and optimization of tailored therapies. Positron-emission tomography (PET), magnetic resonance imaging (MRI), and contrast-enhanced computed tomography (CT) may offer additional information not otherwise available to the operator during minimally invasive image-guided procedures, such as biopsy and ablation. With use of multimodality image fusion for image-guided interventions, navigation with advanced modalities does not require the physical presence of the PET, MRI, or CT imaging system. Several commercially available methods of image-fusion and device navigation are reviewed along with an explanation of common tracking hardware and software. An overview of current clinical applications for multimodality navigation is provided.

  17. Interferometric diagnostics for magnetic spots detection

    NASA Astrophysics Data System (ADS)

    Ligi, R.

    2014-09-01

    The signature of activity in general, and of stellar magnetic spots in particular, is present in every measurements, including interferometric ones. Indeed, stellar spots can be found on many stellar surfaces, their size and number varying according to their host's magnetic field and rotational velocity. To correctly determine stellar parameters, it is thus necessary to determine and extract stellar activity's signals. Interferometric observables are disturbed by activity, and this observing technique thus constitutes a good way of probing stellar surface. However, magnetic spots sometimes mimic other phenomenon, like a transiting exoplanet. In that case, the combination of several observing techniques, like photometry and interferometry, is mandatory to extract the planetary signal from the spot's one, and then characterize the exoplanet.

  18. TOPICAL REVIEW: Shearography technology and applications: a review

    NASA Astrophysics Data System (ADS)

    Francis, D.; Tatam, R. P.; Groves, R. M.

    2010-10-01

    Shearography is a full-field speckle interferometric technique used to determine surface displacement derivatives. For an interferometric technique, shearography is particularly resilient to environmental disturbances and has hence become an invaluable measurement tool outside of the optics laboratory. Furthermore, the inclusion of additional measurement channels has turned shearography from a qualitative inspection tool into a system suitable for quantitative surface strain measurement. In this review article we present a comprehensive overview of the technique, describing the principle of operation, optical configurations, image processing algorithms and applications, with a focus on more recent technological advances.

  19. Analysis of the interferometric Ronchi test.

    PubMed

    Malacara, D

    1990-09-01

    It is well known that the Ronchi test has two equivalent interpretations, Physical, as an interferometer, or geometrical, as if the fringes were just shadows from the fringes on the ruling. The second interpretation is nearly always used in practice because it is simpler. However, the disadvantage is that the irradiance profile of the fringes cannot be calculated with this theory. Here, the interferometric interpretation of the test will be used to obtain the irradiance profile and the sharpness of the fringes.

  20. Speckle-interferometric camera for displacement measurements

    NASA Astrophysics Data System (ADS)

    Klumpp, P. A.; Schnack, E.

    1990-12-01

    A simple setup of standard optical elements comparable to a shearographic camera can be used used to record speckle interferograms with a fast lens. Rigid-body translations of the object are compensated for by a reference mirror attached to the object; the method requires only moderate stability and resolution of the storage medium (film). Interferogram reconstruction is possible with white light. Hence the method unites advances of different holographic and speckle-interferometric setups.