Bulletin of the American Physical Society
2006 APS March Meeting
Monday–Friday, March 13–17, 2006; Baltimore, MD
Session R9: Imaging, Signal Detection and Processing |
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Sponsoring Units: GIMS Chair: Karen Waldrip, Sandia National Laboratories Room: Baltimore Convention Center 301 |
Wednesday, March 15, 2006 2:30PM - 2:42PM |
R9.00001: A single pixel camera based on compressed sensing Kevin Kelly, Dharmpal Takhar, Jason Laska, Mike Wakin, Marco Duarte, Brian Van Osdol, Dror Baron, Richard Baraniuk Digital micromirror devices have proven to be a commercially viable MEMs technology for the video/projector display market. Inspired by the success of this technology, we have combined a microcontrolled mirror with a single optical sensor so that it additionally acquire images, rather than merely adapt current camera technology to serve as an optical sensor. In this project, we have developed a practical image/video camera based on this concept and realized it through the use of \textit{compressed sensing}. Our design has additional desirable properties including scalable output bit stream, variable image resolutions and video frame rates. We will also discuss the generalization of \textit{compressed sensing} as a way of image formation for other single detector systems. [Preview Abstract] |
Wednesday, March 15, 2006 2:42PM - 2:54PM |
R9.00002: Low temperature confocal microscopy with a 4 K closed-cycle cryostat Angelika Kueng, Christoph Boedefeld, Christian Schulhauser, Matthias Buehler, Jens Hoehne Low temperature confocal microscopy is a technique of major interest with regard to research fields ranging from material and surface science to single molecule spectroscopy. Common setups involve the use of expensive liquid helium and suffer from the lack of coarse positioning units at cryogenic temperatures. We present for the first time a highly flexible confocal microscope combined with a 4 K closed-cycle cryostat. This complete system solution enables plug-and-play high resolution confocal microscopy at low temperatures without the need of liquid helium. The low-vibration pulse tube based cryostat has been specially adapted for very low vibrations as required for applications in combination with scanning probe microscopy. The developed confocal microscope is thermally compensated guaranteeing ultra-high stability at low temperature providing at the same time very high optical resolution as will be shown in various examples. Furthermore, nanopositioning units based on the slip-stick principle allow coarse positioning over centimeters. The system allows operation at extreme conditions as high magnetic fields and high vacuum. [Preview Abstract] |
Wednesday, March 15, 2006 2:54PM - 3:06PM |
R9.00003: 4Pi Spectral Self-interference Fluorescence Microscopy Mehmet Dogan, Anna K. Swan, M. Selim Unlu, Bennett B. Goldberg 4Pi fluorescence confocal microscopy [1] improves axial resolution, and Spectral Self-Interference Fluorescence Microscopy (SSFM) [2] provides sub-nanometer localization of fluorescent emitters in biological structures. Here we report on the construction and evaluation of a 4Pi fluorescence confocal microscope and discuss the efforts to combine the high resolution 4Pi technique with SSFM. In the 4Pi microscope, the back focal planes of two opposing high numerical aperture objectives are filled with coherent laser illumination and counter propagating spherical wave fronts form constructive interference at the common focus of two objectives, resulting in an improvement of the axial point spread function (PSF). We characterized the 3-D PSF of the microscope using fluorescent polystyrene beads and fluorescent monolayers. We measured a factor of 3 improvement of the axial PSF compared to a confocal microscope. [1] S. W. Hell et al. J.Opt.Soc.Am. A Vol.9, No.12, pp.2159 (1992) [2] A. K. Swan et al. IEEE JSTQE Vol. 9, No. 2, pp. 294 (2003) [Preview Abstract] |
Wednesday, March 15, 2006 3:06PM - 3:18PM |
R9.00004: Enhancing Diffraction-Limited Images Using the Properties of the Point Spread Function Alexander Small, Ilko Ilev, Amir Gandjbakhche We propose a simple method for enhancing diffraction-limited microscope images, enhancing the resolution by at least a factor of two. In its simplest implementation, our algorithm is ideally suited for enhancing images obtained with near-field illumination, such as scanning probe microscopy of cells. We exploit the fact that the finite width of the point spread function introduces correlations between pixels in an image. Our method is much simpler than other methods for beating the diffraction limit, requiring no specialized equipment beyond the microscopes commonly found in biology laboratories, and only a single computational step to yield significant enhancements. We have theoretically analyzed the performance of our algorithm by generating images with point objects, and convolving those images with the point spread function (PSF) of a diffraction- limited lens. After enhancing the resulting images, we find that our method reduces the width of the PSF by a factor of two, and also yields a much steeper profile, enhancing contrast. Even when objects are too close to be resolved distinctly, our method enhances the aspect ratio of the resulting diffraction blur, clearly pointing to the existence of structure. [Preview Abstract] |
Wednesday, March 15, 2006 3:18PM - 3:30PM |
R9.00005: Feasibility of using Backscattered Mueller Matrix Images for Bioaerosol Detection Changhui Li, George W. Kattawar It has been shown that by looking at the backscattered radiance from an object illuminated by a laser beam one could effectively distinguish different morphologies from one another. However, if one wants to obtain all the information possible from elastic scattering either from a single particle or an ensemble of particles then one must use the Mueller matrix which contains all the polarization and radiance information available. In this talk, we will show that if we take advantage of the polarization information of the object, many more images related to the overall morphology as well as the internal structure of the object can be obtained. We will present images of the complete Mueller matrix to show the sensitivity of its sixteen components to both external and internal particle properties. We will also show that by using only one or two elements of this matrix one might be able to distinguish bioaerosols such as anthrax from more benign aerosols. We also show that the backscattering Mueller images contain more information than the forward scattering ones. [Preview Abstract] |
Wednesday, March 15, 2006 3:30PM - 3:42PM |
R9.00006: The Role of Hyperspectral Imaging in the Visualization of Obliterated Writings Hina Ayub, Diane Williams The forensic questioned document community has encountered difficulty visualizing obliterated writing using conventional methods. Cases have been reported in which pencil obliterated by ink, and ink obliterated by ink, cannot be discerned visually. Conventional methods for visualization of obliterated writings do not adequately visualize writing when obliteration is made with the same color ink, or when graphite pencil writings are obliterated by ink. We report the use of hyperspectral imaging to successfully view obliterated writings in which a ``true black'' ink obliterated graphite as well as graphite/graphite and ink/ink obliterations. Hyperspectral imaging (HSI) is a novel optical technique in which hundreds of narrow contiguous bands, over a large range of wavelengths, can be viewed to yield a complete spectral profile at each pixel in the image. HSI has evolved as the product of conventional two-dimensional imaging and spectroscopy. The resultant image of HSI is a three-dimensional data cube, with the pixels constrained to a single plane, and the complete reflectance spectra seen along the orthogonal axis. We used three types of hyperspectral imaging systems, which provided a wavelength range spanning approximately 300-1700 nm, to visualize the obliterated writing samples. Additionally, we will present data obtained from the use of thermal imaging to successfully view obliterated writings. [Preview Abstract] |
Wednesday, March 15, 2006 3:42PM - 3:54PM |
R9.00007: Femto-second real-time single-shot digitizer Jason Chou, Ozdal Boyraz, Bahram Jalali We demonstrate a single-shot digitizer with a record 10 Tera Sample-per-Second sampling rate, an order of magnitude improvement over prior state-of-the-art. The feat is accomplished by using a photonic time stretch preprocessor which slows down the electrical waveform by a factor of 250 before it is captured by an electronic digitizer. To achieve this performance, distributed Raman optical amplification was realized in the dispersive medium that performs the time dilation. Experimentally, a 90 GHz electrical signal is digitized in real time at 100 femto-second intervals. To the best of our knowledge, this is the first femto-second real-time digitizer. [Preview Abstract] |
Wednesday, March 15, 2006 3:54PM - 4:06PM |
R9.00008: A photopyroelectric sensor for the high-resolution thermophysical characterization of liquid mixtures. Anna Matvienko, Andreas Mandelis A common principle of photothermal techniques is the study of thermal wave propagation in a sample following heating by an intensity modulated laser beam. In this study, we applied the photopyroelectric thermal-wave cavity technique with the common-mode-rejection demodulation scheme to the measurements of thermal diffusivity of water-alcohol mixtures at low concentrations. The high sensitivity of the photothermal signal to the thermal diffusivity of samples relies on the exponential decay character of the thermal-wave field at a given modulation frequency. The common-mode-rejection demodulation scheme involves the launching of two unequal duration pulses over one modulation period. In this case, the lock-in amplifier output represents the difference between the response waves produced by each one of two pulses. This differential technique shows resolution at the level of 0.2{\%} v/v of alcohol in water, the highest ever reported using thermophysical techniques. In terms of future applications the proposed system can eventually be implemented into a self-contained in-situ liquid pollution monitor. [Preview Abstract] |
Wednesday, March 15, 2006 4:06PM - 4:18PM |
R9.00009: Johnson Noise Thermometry in the range 505 K to 933 K Weston Tew, John Labenski, Sae Woo Nam, Samuel Benz, Paul Dresselhaus, John Martinis The International Temperature Scale of 1990 (ITS-90) is an artifact-based temperature scale, $T_{90}$, designed to approximate thermodynamic temperature $T$. The thermodynamic errors of the ITS-90, characterized as the value of $T-T_{90}$, only recently have been quantified by primary thermodynamic methods. Johnson Noise Thermometry (JNT) is a primary method which can be applied over wide temperature ranges, and NIST is currently using JNT to determine $T-T_{90}$ in the range 505~K to 933 K, overlapping both acoustic gas-based and radiation-based thermometry. Advances in digital electronics have now made the computationally intensive processing required for JNT viable using noise voltage correlation in the frequency domain. We have also optimized the design of the 5-wire JNT temperature probes to minimize electromagnetic interference and transmission line effects. Statistical uncertainties under 50~$\mu $K/K are achievable using relatively modest bandwidths of $\sim $100 kHz. The NIST JNT system will provide critical data for $T-T_{90}$ linking together the highly accurate acoustic gas-based data at lower temperatures with the higher-temperature radiation-based data, forming the basis for a new International Temperature Scale with greatly improved thermodynamic accuracy. [Preview Abstract] |
Wednesday, March 15, 2006 4:18PM - 4:30PM |
R9.00010: Using Temperature-Dependent Phenomena at Oxide Surfaces for Species Recognition in Chemical Sensing. Steve Semancik, Douglas Meier, Jon Evju, Kurt Benkstein, Zvi Boger, Chip Montgomery Nanostructured films of SnO$_{2}$ and TiO$_{2}$ have been deposited on elements in MEMS arrays to fabricate solid state conductometric gas microsensors. The multilevel platforms within an array, called microhotplates, are individually addressable for localized temperature control and measurement of sensing film electrical conductance. Temperature variations of the microhotplates are employed in thermally-activated CVD oxide film growth, and for rapid temperature-programmed operation of the microsensors. Analytical information on environmental gas phase composition is produced temporally as purposeful thermal fluctuations provide energetic and kinetic control of surface reaction and adsorption/desorption phenomena. Resulting modulations of oxide adsorbate populations cause changing charge transfer behavior and measurable conductance responses. Rich data streams from different sensing films in the arrays have been analyzed by Artificial Neural Networks (ANN) to successfully recognize low concentration species in mixed gases. We illustrate capabilities of the approach and technology in the homeland security area, where dangerous chemicals (TICs, CWSs and CWAs) have been detected at 10-100 ppb levels in interference-spiked air backgrounds. [Preview Abstract] |
Wednesday, March 15, 2006 4:30PM - 4:42PM |
R9.00011: 2D Thermal Imaging of the Surfaces of Optoelectronic Devices by Thermoreflectance Microscopy M. Farzaneh, D. L\"{u}er{\ss}en, P. Mayer, R. J. Ram, Janice A. Hudgings For the last 40 years, thermoreflectance has been used to experimentally validate bandstructure calculations for semiconductor and metallic materials. The recent development of high resolution thermoreflectance microscopy as a noninvasive, 2D thermal imaging technique, based on measuring the variations of the surface reflectivity with temperature opens new avenues of probing the nanoscale properties of materials and devices. Recently, we have demonstrated that by utilizing stochastic resonance a thermal resolution of 10mK can be achieved, which exceeds the quantization limit of the camera by two orders of magnitude. Here, we report the use of thermoreflectance to characterize a photonic integrated circuit comprised of cascaded semiconductor optical amplifiers. Optical cooling of the biased amplifiers by 0.5K is observed which demonstrates the high spatial and thermal resolution achievable with stochastic resonance enhanced thermoreflectance microscopy. [Preview Abstract] |
Wednesday, March 15, 2006 4:42PM - 4:54PM |
R9.00012: Suppression of Non-Resonant Background in Broadband Coherent Anti-Stokes Raman Scattering Microscopy with Interferometry Tak Kee, Marcus Cicerone We demonstrate an interferometric technique for suppressing non-resonant background in broadband coherent anti-Stokes Raman scattering (CARS) microscopy. CARS microscopy has become an important biological imaging tool due to its non-invasiveness, and high spatial resolution. Our previous work on developing broadband CARS microscopy has improved the chemical specificity significantly by increasing the spectral coverage to $>$ 2500 cm$^{-1}$ [T.W. Kee, M.T. Cicerone, \textit{Opt. Lett.} \textbf{29}, 2701 (2004)]. Although CARS microscopy provides high sensitivity in the C-H stretch region of the vibrational spectrum, the signals in the Raman fingerprint region suffer from low signal-to-background ratio because of the presence of a non-resonant background due to the electronic response of the sample. Suppressing the non-resonant background signal is crucial in order to develop CARS microscopy into a powerful technique to image biochemical reactions in cells. In our approach, a broadband CARS signal with high spectral resolution interferes with another broadband CARS signal with lower spectral resolution. Fourier transform of the interferometric measurements allow the extraction of the imaginary part of the signal, which is free of the non-resonant background. [Preview Abstract] |
Wednesday, March 15, 2006 4:54PM - 5:06PM |
R9.00013: Digital ultrasonic pulse-echo overlap system and algorithm for unambiguous determination of pulse transit time Cristian Pantea, Dwight Rickel, Albert Migliori, Jianzhong Zhang, Yusheng Zhao, Sami El-Khatib, Robert Leisure, Baosheng Li We report an evolution of an all-digital ultrasonic pulse technique for measurements of elastic constants of solids. An unambiguous analytical procedure is described for determining the correct time delay of echoes without any need for actual echo overlap. We also provide a simple procedure for making corrections for transducer-bond-induced phase shifts. The precision of a measurement made with this system at ambient temperature exceeds one part in 10$^{7}$ without the use of mixers, gates, time delays, and other complications normally associated with such measurements. [Preview Abstract] |
Wednesday, March 15, 2006 5:06PM - 5:18PM |
R9.00014: Application of the finite element method to resonant ultrasound spectroscopy data analysis. A. Suslov, I. Dixon, S. Headley, E. Deyle, A. Migliori Commercially available finite-element software is used to determine elastic moduli from experimental data acquired by resonant ultrasound spectroscopy (RUS) on an arbitrarily-shaped sample. The sample geometry must be provided in coordinate form, as well as the crystallographic symmetry and the crystallographic orientation relative to the coordinates. The algorithm has been tested on published resonance measurements obtained on rectangular parallelepipeds and cylinders of cubic, tetragonal, hexagonal and monoclinic symmetries. The results agree within expected numerical precision to the elastic constants found by other computational methods. The algorithm is much slower than the one normally implemented explicitly for RUS analysis but, for difficult-to-prepare or fragile samples such as a layered specimen prepared from several materials, moduli can be obtained without polishing or otherwise damaging the sample. Details of the model generation, meshing and optimization approach will be discussed. [Preview Abstract] |
Wednesday, March 15, 2006 5:18PM - 5:30PM |
R9.00015: Source distance information and frequency shifts by chirp decomposition V. Guruprasad Innovative frequency shifts directly revealing the source distance of received signals are obtainable from phase spectra as follows. The phase expression for a travelling wave, $\phi = - \omega(t - r/c)$, implies increasing static phase differences $\delta \phi(r) = r \, \delta \omega/c$ between adjacent frequencies in the radiated waves. The static differences are useless for information transport and hard to measure, hence were hitherto generally ignored. Scanning the spectrum transforms them to Doppler-like shifts revealing the distance, given by the partial derivative $\delta\omega(r)=\left.\partial\phi/\partial t\right|_{r,t}=\dot{\omega}r/c$, where $\dot{\omega}$ is the scanning rate, provided the signal has nonzero bandwidth. By controlling $\dot{\omega}$, any source can now be instantly ranged or isolated, allowing separations down to 10 m at 100 m range for 10 MHz voice modulated carrier -- without CDMA or power control, as described at IEEE WCNC 2005. The mechanism is also realizable by simple chirp transform, and has been verified by simulation and with acoustic signals. EM field tests are now being arranged. The results and other aspects of general physics interest will be discussed. [Preview Abstract] |
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