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Sample records for interferometry ice-radar measurement

  1. Columbia Glacier stake location, mass balance, glacier surface altitude, and ice radar data, 1978 measurement year

    USGS Publications Warehouse

    Mayo, L.R.; Trabant, D.C.; March, Rod; Haeberli, Wilfried

    1979-01-01

    A 1 year data-collection program on Columbia Glacier, Alaska has produced a data set consisting of near-surface ice kinematics, mass balance, and altitude change at 57 points and 34 ice radar soundings. These data presented in two tables, are part of the basic data required for glacier dynamic analysis, computer models, and predictions of the number and size of icebergs which Columbia Glacier will calve into shipping lanes of eastern Prince William Sound. A metric, sea-level coordinate system was developed for use in surveying throughout the basin. Its use is explained and monument coordinates listed. A series of seven integrated programs for calculators were used in both the field and office to reduce the surveying data. These programs are thoroughly documented and explained in the report. (Kosco-USGS)

  2. Measuring Speeds with Microwave Interferometry

    NASA Astrophysics Data System (ADS)

    Hillberry, Logan

    2014-03-01

    The speed of an approximately frictionless cart is simultaneously measured in two ways. A 10.5 GHz microwave source is used in the familiar Michelson interferometry setup with one of the arms being the mobile cart and the other being a stationary microwave receiver. As the cart travels, the changing interference pattern is captured on an oscilloscope which, when combined with the source frequency, can be used to determine the cart's speed. The second speed measurement is achieved by sending a laser beam across the cart's path into a photo detector which is connected a second channel on the oscilloscope. The cart breaks the beam and travels a distance equal to its length before allowing the beam to reach the photo detector again. Using the oscilloscope's timing measurement and the known cart length, one can readily calculate the cart's speed. Comparison of the two methods conveys agreement within error, confirming the path length difference model used to calculate the speed of the cart in the microwave interferometry method.

  3. Atom Interferometry for Fundamental Physics and Gravity Measurements in Space

    NASA Technical Reports Server (NTRS)

    Kohel, James M.

    2012-01-01

    Laser-cooled atoms are used as freefall test masses. The gravitational acceleration on atoms is measured by atom-wave interferometry. The fundamental concept behind atom interferometry is the quantum mechanical particle-wave duality. One can exploit the wave-like nature of atoms to construct an atom interferometer based on matter waves analogous to laser interferometers.

  4. Comparing Laser Interferometry and Atom Interferometry Approaches to Space-Based Gravitational-Wave Measurement

    NASA Technical Reports Server (NTRS)

    Baker, John; Thorpe, Ira

    2012-01-01

    Thoroughly studied classic space-based gravitational-wave missions concepts such as the Laser Interferometer Space Antenna (LISA) are based on laser-interferometry techniques. Ongoing developments in atom-interferometry techniques have spurred recently proposed alternative mission concepts. These different approaches can be understood on a common footing. We present an comparative analysis of how each type of instrument responds to some of the noise sources which may limiting gravitational-wave mission concepts. Sensitivity to laser frequency instability is essentially the same for either approach. Spacecraft acceleration reference stability sensitivities are different, allowing smaller spacecraft separations in the atom interferometry approach, but acceleration noise requirements are nonetheless similar. Each approach has distinct additional measurement noise issues.

  5. Defect Depth Measurement Using White Light Interferometry

    NASA Technical Reports Server (NTRS)

    Parker, Don; Starr, Stan

    2009-01-01

    The objectives of the White Light Interferometry project are the following: (1) Demonstrate a small hand-held instrument capable of performing inspections of identified defects on Orbiter outer pane window surfaces. (2) Build and field-test a prototype device using miniaturized optical components. (3) Modify the instrument based on field testing and begin the conversion of the unit to become a certified shop-aid.

  6. Interferometry

    NASA Technical Reports Server (NTRS)

    Ridgway, Stephen; Wilson, Robert W.; Begelman, Mitchell C.; Bender, Peter; Burke, Bernard F.; Cornwell, Tim; Drever, Ronald; Dyck, H. Melvin; Johnston, Kenneth J.; Kibblewhite, Edward

    1991-01-01

    The following recommended programs are reviewed: (1) infrared and optical interferometry (a ground-based and space programs); (2) compensation for the atmosphere with adaptive optics (a program for development and implementation of adaptive optics); and (3) gravitational waves (high frequency gravitational wave sources (LIGO), low frequency gravitational wave sources (LAGOS), a gravitational wave observatory program, laser gravitational wave observatory in space, and technology development during the 1990's). Prospects for international collaboration and related issues are also discussed.

  7. Digital holographic interferometry for measurement of temperature in axisymmetric flames.

    PubMed

    Sharma, Shobhna; Sheoran, Gyanendra; Shakher, Chandra

    2012-06-01

    In this paper, experimental investigations and analysis is presented to measure the temperature and temperature profile of gaseous flames using lensless Fourier transform digital holographic interferometry. The evaluations of the experimental results give the accuracy, sensitivity, spatial resolution, and range of measurements to be well within the experimental limits. Details of the experimental results and analysis are presented. PMID:22695554

  8. Terahertz reflection interferometry for automobile paint layer thickness measurement

    NASA Astrophysics Data System (ADS)

    Rahman, Aunik; Tator, Kenneth; Rahman, Anis

    2015-05-01

    Non-destructive terahertz reflection interferometry offers many advantages for sub-surface inspection such as interrogation of hidden defects and measurement of layers' thicknesses. Here, we describe a terahertz reflection interferometry (TRI) technique for non-contact measurement of paint panels where the paint is comprised of different layers of primer, basecoat, topcoat and clearcoat. Terahertz interferograms were generated by reflection from different layers of paints on a metallic substrate. These interferograms' peak spacing arising from the delay-time response of respective layers, allow one to model the thicknesses of the constituent layers. Interferograms generated at different incident angles show that the interferograms are more pronounced at certain angles than others. This "optimum" angle is also a function of different paint and substrate combinations. An automated angular scanning algorithm helps visualizing the evolution of the interferograms as a function of incident angle and also enables the identification of optimum reflection angle for a given paint-substrate combination. Additionally, scanning at different points on a substrate reveals that there are observable variations from one point to another of the same sample over its entire surface area. This ability may be used as a quality control tool for in-situ inspection in a production line. Keywords: Terahertz reflective interferometry, Paint and coating layers, Non-destructive

  9. Infrasonic interferometry applied to synthetic and measured data

    NASA Astrophysics Data System (ADS)

    Fricke, Julius T.; Evers, Läslo G.; Ruigrok, Elmer; Wapenaar, Kees; Simons, Dick G.

    2013-04-01

    The estimation of the traveltime of infrasound through the atmosphere is interesting for several applications. For example, it could be used to determine temperature and wind of the atmosphere, since the traveltime depends on these atmospheric conditions (Haney, 2009). In this work the traveltime is estimated with infrasonic interferometry. In other words, we calculate the crosscorrelations of data of spatially distributed receivers. With this method the traveltime between two receivers is determined without the need for ground truth events. In a first step, we crosscorrelate synthetic data, which are generated by a raytracing model. This model takes into account the traveltime along the rays, the attenuation of the different atmospheric layers, the spreading of the rays and the influence of caustics. In these numerical experiments we show that it is possible to determine the traveltime through infrasonic interferometry. We present the results of infrasonic interferometry applied to measured data. Microbaroms are used in the crosscorrelation approach. Microbaroms are caused by ocean waves and are measured by the 'Large Aperture Infrasound Array' (LAIA). LAIA is being installed by the Royal Netherlands Meteorological Institute (KNMI) in the framework of the radio-astronomical 'Low Frequency Array' (LOFAR) initiative. LAIA consists currently of around twenty receivers (microbarometers) with an aperture of around 100 km, allowing for several inter-station distances. Here, we show the results of crosscorrelations as a function of receivers distance, to assess the signal coherency. This research is made possible by the support of the 'Netherlands Organization for Scientific Research' (NWO). Haney, M., 2009. Infrasonic ambient noise interferometry from correlations of microbaroms, Geophysical Research Letters, 36, L19808

  10. Electron density measurement by differential interferometry

    SciTech Connect

    Ding, W. X.; Brower, D. L.; Deng, B. H.; Yates, T.

    2006-10-15

    A novel differential interferometer is being developed to measure the electron density gradient and its fluctuations. Two separate laser beams with slight spatial offset and frequency difference are coupled into a single mixer making a heterodyne measurement of the phase difference which is <1% of the total phase change experienced by each beam separately. This measure of the differential phase is made at multiple spatial points and can be inverted directly to provide the local density distribution.

  11. IMAP: Interferometry for Material Property Measurement in MEMS

    SciTech Connect

    Jensen, B.D.; Miller, S.L.; de Boer, M.P.

    1999-03-10

    An interferometric technique has been developed for non-destructive, high-confidence, in-situ determination of material properties in MEMS. By using interferometry to measure the full deflection curves of beams pulled toward the substrate under electrostatic loads, the actual behavior of the beams has been modeled. No other method for determining material properties allows such detailed knowledge of device behavior to be gathered. Values for material properties and non-idealities (such as support post compliance) have then been extracted which minimize the error between the measured and modeled deflections. High accuracy and resolution have been demonstrated, allowing the measurements to be used to enhance process control.

  12. Measurement of the gravity-field curvature by atom interferometry.

    PubMed

    Rosi, G; Cacciapuoti, L; Sorrentino, F; Menchetti, M; Prevedelli, M; Tino, G M

    2015-01-01

    We present the first direct measurement of the gravity-field curvature based on three conjugated atom interferometers. Three atomic clouds launched in the vertical direction are simultaneously interrogated by the same atom interferometry sequence and used to probe the gravity field at three equally spaced positions. The vertical component of the gravity-field curvature generated by nearby source masses is measured from the difference between adjacent gravity gradient values. Curvature measurements are of interest in geodesy studies and for the validation of gravitational models of the surrounding environment. The possibility of using such a scheme for a new determination of the Newtonian constant of gravity is also discussed. PMID:25615464

  13. Semiconductor Laser Linewidth Measurements for Space Interferometry Applications

    NASA Technical Reports Server (NTRS)

    Dougherty, D. J.; Guttierrez, R. C.; Dubovitsky, S.; Forouhar, S.

    2000-01-01

    Narrow linewidth (<100KHz) semiconductor lasers are expected to be a key technology in NASA's stellar interferometry missions to search for planets around nearby stars. Long coherence length lasers are needed for precise (20 pm to 5 mn) measurements of the optical path difference. This work discusses results using the self-heterodyne delay technique to measure 1.3 micrometer InP based DFB lasers. We will also address practical issues concerning detection and elimination of back reflections, choice of fiber length and resolution, and measurement of laser 1/f and current supply noise.

  14. Absolute distance measurements by variable wavelength interferometry

    NASA Astrophysics Data System (ADS)

    Bien, F.; Camac, M.; Caulfield, H. J.; Ezekiel, S.

    1981-02-01

    This paper describes a laser interferometer which provides absolute distance measurements using tunable lasers. An active feedback loop system, in which the laser frequency is locked to the optical path length difference of the interferometer, is used to tune the laser wavelengths. If the two wavelengths are very close, electronic frequency counters can be used to measure the beat frequency between the two laser frequencies and thus to determine the optical path difference between the two legs of the interferometer.

  15. Pulsed thrust measurements using laser interferometry

    NASA Astrophysics Data System (ADS)

    Cubbin, E. A.; Ziemer, J. K.; Choueiri, E. Y.; Jahn, R. G.

    1997-06-01

    An optical interferometric proximeter system (IPS) for measuring thrust and impulse bit of pulsed electric thrusters was developed. Unlike existing thrust stands, the IPS-based thrust stand offers the advantage of a single system that can yield electromagnetic interference-free, high accuracy (<2% error) thrust measurements within a very wide range of impulses (100 μN s to above 10 N s) covering the impulse range of all known pulsed plasma thrusters. In addition to pulsed thrusters, the IPS is theoretically shown to be capable of measuring steady-state thrust values as low as 20 μN for microthrusters such as the field emission electric propulsion thruster. The IPS-based thrust stand relies on measuring the dynamic response of a swinging arm using a two-sensor laser interferometer with 10 nm position accuracy. The wide application of the thrust stand is demonstrated with thrust measurements of an ablative pulsed plasma thruster and a quasi-steady magnetoplasmadynamic thruster.

  16. Skin-friction measurements by laser interferometry

    NASA Technical Reports Server (NTRS)

    Kim, K.-S.; Settles, G. S.

    1989-01-01

    The measurement of skin friction in rapidly distorted compressible flows is difficult, and very few reliable techniques are available. A recent development, the laser interferometer skin friction (LISF) meter, promises to be useful for this purpose. This technique interferometrically measures the time rate of thinning of an oil film applied to an aerodynamic surface. Under the proper conditions the wall shear stress may thus be found directly, without reference to flow properties. The applicability of the LISF meter to supersonic boundary layers is examined experimentally. Its accuracy and repeatability are assessed, and conditions required for its successful application are considered.

  17. Refractive index measurement using comparative interferometry

    NASA Astrophysics Data System (ADS)

    Bojan, Mihaela; Apostol, D.; Damian, V.; Logofatu, P. C.; Garoi, F.; Iordache, Iuliana

    2007-05-01

    The refractive index of a material medium is an important optical parameter since it exhibits the optical properties of the material. The adulteration problem is increasing day by day and hence simple, automatic and accurate measurement of the refractive index of materials is of great importance these days. For solid thin films materials Abeles method was reconsidered. Quick, measurements of refractive index using simple techniques and refractometers can help controlling adulteration of liquids of common use to a greater extent. Very simple interferometric set-up using Fizeau fringe patterns compares the fringe pitch as obtained in a cell with two levels: one down level with the unknown refractive index liquids and the upper level with gas air. A CCD matrix and a PC can handle the data and produce the results up to for digits.

  18. Measurements of Laser Imprinting Using 2-D Velocity Interferometry

    NASA Astrophysics Data System (ADS)

    Boehly, T. R.; Fiksel, G.; Hu, S. X.; Goncharov, V. N.; Sangster, T. C.; Celliers, P. M.

    2014-10-01

    Evaluating laser imprinting and its effect on target performance is critical to direct-drive inertial confinement fusion research. Using high-resolution velocity interferometry, we measure modulations in the velocity of shock waves produced by the 351-nm beams on OMEGA. These modulations result from nonuniformities in the drive laser beams. We use these measurements to evaluate the effect on imprinting of multibeam irradiation and metal layers on both plastic and cryogenic deuterium targets driven with 100-ps pulses. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  19. Measurement of gauge blocks by interferometry

    NASA Astrophysics Data System (ADS)

    Matus, M.; Haas, S.; Piree, H.; Gavalyugov, V.; Tamakyarska, D.; Thalmann, R.; Balling, P.; Garnaes, J.; Hald, J.; Farid, N.; Prieto, E.; Lassila, A.; Salgado, J. A.; Lewis, A.; Bandis, C.; Mudronja, V.; Banreti, E.; Balsamo, A.; Pedone, P.; Bergmans, R. H.; Karlsson, H.; Ramotowski, Z.; Eusebio, L.; Saraiva, F.; Duta, A.; Zelenika, S.; Bergstrand, S.; Fira, R.; Yandayan, T.; Sendogdu, D.; Ganioglu, O.; Asli Akgoz, S.; Franke, P.

    2016-01-01

    The key comparison EURAMET.L-K1.2011 on gauge blocks was carried out in the framework of a EURAMET project starting in 2012 and ending in 2015. It involved the participation of 24 National Metrology Institutes from Europe and Egypt, respectively. 38 gauge blocks of steel and ceramic with nominal central lengths between 0.5 mm and 500 mm were circulated. The comparison was conducted in two loops with two sets of artifacts. A statistical technique for linking the reference values was applied. As a consequence the reference value of one loop is influenced by the measurements of the other loop although they did not even see the artifacts of the others. This influence comes solely from three "linking laboratories" which measure both sets of artifacts. In total there were 44 results were not fully consistent with the reference values. This represents 10% of the full set of 420 results which is a considerable high number. At least 12 of them are clearly outliers where the participants have been informed by the pilot as soon as possible. The comparison results help to support the calibration and measurement capabilities (CMCs) of the laboratories involved in the CIPM MRA. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  20. Precision Measurements with Matter-wave Interferometry

    NASA Astrophysics Data System (ADS)

    Erickson, Christopher; Christensen, Dan; Washburn, Matthew; Archibald, James; van Zjill, Marshall; Birrell, Jeremiah; Burdett, Adam; Durfee, Dallin

    2007-06-01

    We will discuss progress on a neutral-calcium beam interferometer which is nearing completion. We will also present a proposal to measure electric and magnetic fields with extreme precision using a slow ion interferometer. The calcium interferometer utilizes a thermal beam for simplicity and high atom flux. Doppler shifts will be reduced using a novel alignment scheme for the Ramsey beams using precision prisms. The ion interferometer will utilize a slow beam of strontium-87 ions created by photon-ionizing a slow atomic beam. The ions will interact with three sets of laser beams which will drive stimulated Raman transitions. The proposed device will be used to search for variations from Coulomb's inverse-square law and a possible photon rest mass with a precision which is several orders of magnitude better than previous laboratory experiments.

  1. Automated small tilt-angle measurement using Lau interferometry

    SciTech Connect

    Prakash, Shashi; Singh, Sumitra; Rana, Santosh

    2005-10-01

    A technique for a tilt-angle measurement of reflecting objects based on the Lau interferometry coupled with the moire readout has been proposed. A white-light incoherent source illuminates a set of two gratings, resulting in the generation of the Fresnel image due to the Lau effect. The Fresnel image is projected onto a reflecting object. The image reflected from the object is superimposed onto an identical grating, which results in the formation of a moire fringe pattern. The inclination angle of moire fringes is a function of tilt angle of the object. Theory and experimental arrangement of the proposed technique is presented and results of the investigation are reported.

  2. The application of VLB interferometry to earth measurements

    NASA Technical Reports Server (NTRS)

    Michelini, R. D.

    1973-01-01

    Results of a four-phase development of capability in very long-baseline interferometry (VLBI) at the Smithsonian Astrophysical Observatory (SAO) are summarized. The objectives of the VLBI program at SAO are to: (1) develop the capability to collect, process, and analyze VLBI data; (2) determine experimentally the accuracy now attainable with VLBI and, within the constraints imposed by this accuracy, initiate a program of VLBI observations for geophysical applications; (3) identify all significant error sources and devise means for eliminating or correcting these errors; and (4) develop a long range plan for applying VLBI techniques to a program of earth physics measurements.

  3. Equivalent wavelength self-mixing interferometry for displacement measurement.

    PubMed

    Huang, Zhen; Li, Chengwei; Li, Songquan; Li, Dongyu

    2016-09-01

    In order to improve fringe precision of a self-mixing signal, a simple and effective method based on an equivalent wavelength self-mixing interferometer is presented. And a linearization fringe counting method is proposed for equivalent wavelength self-mixing interferometry to quickly reconstruct target displacement. The validity of the proposed method was demonstrated by means of simulated signals and confirmed by several experimental measurements for both harmonic and aleatory target displacement with a fringe resolution of ∼125  nm. PMID:27607290

  4. Magnetostriction Measured by Holographic Interferometry with the Simple and Inexpensive "Arrowhead" Setup

    ERIC Educational Resources Information Center

    Ladera, Celso L.; Donoso, Guillermo; Contreras, Johnny H.

    2012-01-01

    Double-exposure holographic interferometry is applied to measure the "linear" or "longitudinal" magnetostriction constant of a soft-ferrite rod. This high-accuracy measurement is done indirectly, by measuring the small rotations of a lever in contact with the rod using double-exposure holographic interferometry implemented with a robust…

  5. Burg algorithm for enhancing measurement performance in wavelength scanning interferometry

    NASA Astrophysics Data System (ADS)

    Woodcock, Rebecca; Muhamedsalih, Hussam; Martin, Haydn; Jiang, Xiangqian

    2016-06-01

    Wavelength scanning interferometry (WSI) is a technique for measuring surface topography that is capable of resolving step discontinuities and does not require any mechanical movement of the apparatus or measurand, allowing measurement times to be reduced substantially in comparison to related techniques. The axial (height) resolution and measurement range in WSI depends in part on the algorithm used to evaluate the spectral interferograms. Previously reported Fourier transform based methods have a number of limitations which is in part due to the short data lengths obtained. This paper compares the performance auto-regressive model based techniques for frequency estimation in WSI. Specifically, the Burg method is compared with established Fourier transform based approaches using both simulation and experimental data taken from a WSI measurement of a step-height sample.

  6. Vibration measurement based on Multiple Self-Mixing Interferometry

    NASA Astrophysics Data System (ADS)

    Jiang, Chunlei; Zhang, Zihua; Li, Chengwei

    2016-05-01

    We propose a novel algorithm for Multiple Self-Mixing Interferometry (MSMI). The algorithm is able to measure nanometer scale vibration by the power spectrum analysis. In the paper, the principles of the method are introduced in detail. The experimental setup has been built. The validity of the proposed algorithm was confirmed by conducting a series of experimental measurements at different reflection times, feedback factors, and vibrational frequencies using PZT as a reference. Experimental results showed that the method can quickly demodulate parameters of vibration and good correspondence between theory and experiment. The proposed algorithm, thus, furnishes nanometer measurements with a very high resolution using a self-aligned, cost effective and compact experimental setup.

  7. Measurement of the electric polarizability of lithium by atom interferometry

    SciTech Connect

    Miffre, A.; Jacquey, M.; Buechner, M.; Trenec, G.; Vigue, J.

    2006-01-15

    We have built an atom interferometer and, by applying an electric field on one of the two interfering beams, we have measured the static electric polarizability of lithium {alpha}=(24.33{+-}0.16)x10{sup -30} m{sup 3} with a 0.66% uncertainty. Our experiment is similar to an experiment done on sodium in 1995 by Pritchard and co-workers, with several improvements: the electric field can be calculated analytically and the interference signals have a large intensity and a high visibility, resulting in accurate phase measurements. This experiment illustrates the extreme sensitivity of atom interferometry: when the atom enters the electric field, its velocity increases and the fractional change, equal to 4x10{sup -9} for our largest field, is measured with a 10{sup -3} accuracy.

  8. Measurement of Rotorcraft Blade Deformation using Projection Moire Interferometry

    NASA Technical Reports Server (NTRS)

    Fleming, Gary A.; Gorton, Susan Althoff

    1998-01-01

    Projection Moire Interferometry (PMI) has been used to obtain near instantaneous, quantitative blade deformation measurements of a generic rotorcraft model at several test conditions. These laser-based measurements provide quantitative, whole field, dynamic blade deformation profiles conditionally sampled as a function of rotor azimuth. The instantaneous nature of the measurements permits computation of the mean and unsteady blade deformation, blade bending, and twist. The PMI method is presented, and the image processing steps required to obtain quantitative deformation profiles from PMI interferograms are described. Experimental results are provided which show blade bending, twist, and unsteady motion. This initial proof-of-concept test has demonstrated the capability of PMI to acquire accurate, full field rotorcraft blade deformation data.

  9. The correction of vibration in frequency scanning interferometry based absolute distance measurement system for dynamic measurements

    NASA Astrophysics Data System (ADS)

    Lu, Cheng; Liu, Guodong; Liu, Bingguo; Chen, Fengdong; Zhuang, Zhitao; Xu, Xinke; Gan, Yu

    2015-10-01

    Absolute distance measurement systems are of significant interest in the field of metrology, which could improve the manufacturing efficiency and accuracy of large assemblies in fields such as aircraft construction, automotive engineering, and the production of modern windmill blades. Frequency scanning interferometry demonstrates noticeable advantages as an absolute distance measurement system which has a high precision and doesn't depend on a cooperative target. In this paper , the influence of inevitable vibration in the frequency scanning interferometry based absolute distance measurement system is analyzed. The distance spectrum is broadened as the existence of Doppler effect caused by vibration, which will bring in a measurement error more than 103 times bigger than the changes of optical path difference. In order to decrease the influence of vibration, the changes of the optical path difference are monitored by a frequency stabilized laser, which runs parallel to the frequency scanning interferometry. The experiment has verified the effectiveness of this method.

  10. Projection Moire Interferometry Measurements of Micro Air Vehicle Wings

    NASA Technical Reports Server (NTRS)

    Fleming, Gary A.; Bartram, Scott M.; Waszak, Martin R.; Jenkins, Luther N.

    2001-01-01

    Projection Moire Interferometry (PMI) has been used to measure the structural deformation of micro air vehicle (MAV) wings during a series of wind tunnel tests. The MAV wings had a highly flexible wing structure, generically reminiscent of a bat s wing, which resulted in significant changes in wing shape as a function of MAV angle-of-attack and simulated flight speed. This flow-adaptable wing deformation is thought to provide enhanced vehicle stability and wind gust alleviation compared to rigid wing designs. Investigation of the potential aerodynamic benefits of a flexible MAV wing required measurement of the wing shape under aerodynamic loads. PMI was used to quantify the aerodynamically induced changes in wing shape for three MAV wings having different structural designs and stiffness characteristics. This paper describes the PMI technique, its application to MAV testing, and presents a portion of the PMI data acquired for the three different MAV wings tested.

  11. Projection moire interferometry measurements of micro air vehicle wings

    NASA Astrophysics Data System (ADS)

    Fleming, Gary A.; Bartram, Scott M.; Waszak, Martin R.; Jenkins, Luther N.

    2001-11-01

    Projection Moire Interferometry (PMI) has been used to measure the structural deformation of micro air vehicle (MAV) wings during a series of wind tunnel tests. The MAV wings had a highly flexible wing structure, generically reminiscent of a bat's wing, which resulted in significant changes in wing shape as a function of MAV angle-of-attack and simulated flight speed. This flow-adaptable wing deformation is thought to provide enhanced vehicle stability and wind gust alleviation compared to rigid wing designs. Investigation of the potential aerodynamic benefits of a flexible MAV wing required measurement of the wing shape under aerodynamic loads. PMI was used to quantify the aerodynamically induced changes in wing shape for three MAV wings having different structural designs and stiffness characteristics. This paper describes the PMI technique, its application to MAV testing, and presents a portion of the PMI data acquired for the three different MAV wings tested.

  12. Electron beam coherence measurements using diffracted beam interferometry/holography.

    PubMed

    Herring, Rodney A

    2009-06-01

    The intensity and coherence of elastically and inelastically scattered electrons have been studied by the interference of electron-diffracted beams using a method of diffracted beam interferometry/holography (DBI/H). In the interferograms produced, fringes were found to exist from low to high scattering angles. The intensity and coherence of the fringes are useful for understanding the contrast mismatch between experimental and simulated images found in atomic resolution images of crystals produced by transmission electron microscopy (TEM) and annular dark-field (ADF) scanning transmission electron microscopy (STEM). The fringes disappear when the interfering beams are separated from an exact overlay position, which produces a measurement of the beam's lateral coherence and holds promise for measuring the coherence of the respective quasi-particles associated with the energy loss electrons. PMID:19141592

  13. Spatial-heterodyne interferometry for transmission (SHIFT) measurements

    DOEpatents

    Bingham, Philip R.; Hanson, Gregory R.; Tobin, Ken W.

    2006-10-10

    Systems and methods are described for spatial-heterodyne interferometry for transmission (SHIFT) measurements. A method includes digitally recording a spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis using a reference beam, and an object beam that is transmitted through an object that is at least partially translucent; Fourier analyzing the digitally recorded spatially-heterodyned hologram, by shifting an original origin of the digitally recorded spatially-heterodyned hologram to sit on top of a spatial-heterodyne carrier frequency defined by an angle between the reference beam and the object beam, to define an analyzed image; digitally filtering the analyzed image to cut off signals around the original origin to define a result; and performing an inverse Fourier transform on the result.

  14. Three-Dimensional Displacement Measurement Using Diffractive Optic Interferometry

    NASA Technical Reports Server (NTRS)

    Gilbert, John A.; Cole, Helen J.; Shepherd, Robert L.; Ashley Paul R.

    1999-01-01

    This paper introduces a powerful new optical method which utilizes diffractive optic interferometry (DOI) to measure both in-plane and out-of-plane displacement with variable sensitivity using the same optical system. Sensitivity is varied by utilizing various combinations of the different wavefronts produced by a conjugate pair of binary Optical elements; a transmission grating is used to produce several illumination beams while a reflective grating replicated on the surface of a specimen, provides the reference for the undeformed state. A derivation of the equations which govern the method is included along with a discussion Of the experimental tests conducted to verify the theory. Overall, the results are excellent, with experimental data agreeing to within a few percent of the theoretical predictions.

  15. First measurement of laser Wakefield oscillations by longitudinal interferometry

    SciTech Connect

    Siders, C.W.; Le Blanc, S.P.; Rau, B.; Fisher, D.; Tajima, T.; Downer, M.C.; Babine, A.; Stepanov, A.; Sergeev, A.

    1996-12-31

    Because the electrostatic fields present in plasma waves can exceed those achievable in conventional accelerators and approach atomic scale values (E{sub a} {approximately} 500 GV/m), plasma based accelerators have received considerable attention as compact sources of high-energy electron pulses. Although stimulated Raman scattering or terahertz radiation at {ital w{sub p}} provided spatially averaged optical signatures of the plasma wave`s existence, new diagnostic techniques are required to map the the temporal and spatial structure of the plasma wave directly since such information is vital for addressing fundamental issues of wakefield generation and propagation. In this paper, we report femtosecond time resolved measurements of the longitudinal and radial structure of laser wakefield oscillations using an all optical technique known as interferometric ``photon acceleration`` or Longitudinal Interferometry.

  16. Measuring Z2 topological invariants in optical lattices using interferometry

    NASA Astrophysics Data System (ADS)

    Grusdt, F.; Abanin, D.; Demler, E.

    2014-04-01

    We propose an interferometric method to measure Z2 topological invariants of time-reversal invariant topological insulators realized with optical lattices in two and three dimensions. We suggest two schemes which both rely on a combination of Bloch oscillations with Ramsey interferometry and can be implemented using standard tools of atomic physics. In contrast to topological Zak phase and Chern number, defined for individual one-dimensional and two-dimensional Bloch bands, the formulation of the Z2 invariant involves at least two Bloch bands related by time-reversal symmetry which one must keep track of in measurements. In one of our schemes this can be achieved by the measurement of Wilson loops, which are non-Abelian generalizations of Zak phases. The winding of their eigenvalues is related to the Z2 invariant. We thereby demonstrate that Wilson loops are not just theoretical concepts but can be measured experimentally. For the second scheme we introduce a generalization of time-reversal polarization which is continuous throughout the Brillouin zone. We show that its winding over half the Brillouin zone yields the Z2 invariant. To measure this winding, our protocol only requires Bloch oscillations within a single band, supplemented by coherent transitions to a second band which can be realized by lattice shaking.

  17. Direct Measurement of Aerosol Absorption Using Photothermal Interferometry

    NASA Astrophysics Data System (ADS)

    Sedlacek, A. J.; Lee, J. A.

    2007-12-01

    Efforts to bound the contribution of light absorption in aerosol radiative forcing is still very much an active area of research in large part because aerosol extinction is dominated by light scattering. In response to this and other technical issues, the aerosol community has actively pursued the development of new instruments to measure aerosol absorption (e.g., photoacoustic spectroscopy (PAS) and multi-angle absorption photometer (MAAP)). In this poster, we introduce the technique of photothermal interferometry (PTI), which combines the direct measurement capabilities of photothermal spectroscopy (PTS) with high-sensitivity detection of the localized heating brought about by the PT process through interferometry. At its most fundamental level, the PTI technique measures the optical pathlength change that one arm of an interferometer (referred to as the 'probe' arm) experiences relative to the other arm of the interferometer (called the 'reference' arm). When the two arms are recombined at a beamsplitter, an interference pattern is created. If the optical pathlength in one arm of the interferometer changes, a commensurate shift in the interference pattern will take place. For the specific application of measuring light absorption, the heating of air surrounding the light- absorbing aerosol following laser illumination induces the optical pathlength change. This localized heating creates a refractive index gradient causing the probe arm of the interferometer to take a slightly different optical pathlength relative to the unperturbed reference arm. This effect is analogous to solar heating of a road causing mirages. As discussed above, this altered optical pathlength results in a shift in the interference pattern that is then detected as a change in the signal intensity by a single element detector. The current optical arrangement utilizes a folded Jamin interferometer design (Sedlacek, 2006) that provides a platform that is robust with respect to sensitivity

  18. The use of holographic interferometry and electron speckle pattern interferometry for diffusion measurement in biochemical and pharmaceutical engineering applications

    NASA Astrophysics Data System (ADS)

    Axelsson, Anders; Marucci, Mariagrazia

    2008-12-01

    In this review holographic interferometry and electron speckle pattern interferometry are discussed as efficient techniques for diffusion measurements in biochemical and pharmaceutical applications. Transport phenomena can be studied, quantitatively and qualitatively, in gels, liquids and membranes. Detailed information on these phenomena is required to design effective chromatography bioseparation processes using gel beads or ultrafiltration membranes, and in the design of controlled-release pharmaceuticals using membrane-coated pellets or tablets. The influence of gel concentration, ion strength in the liquid and the size of diffusing protein molecules can easily be studied with good accuracy. When studying membranes, the resistance can be quantified, and it is also possible to discriminate between permeable and semi-permeable membranes. In this review the influence of temperature, natural convection and light deflection on the accuracy of the diffusion measurements is also discussed.

  19. A trial for a reliable shape measurement using interferometry and deflectometry

    NASA Astrophysics Data System (ADS)

    Hanayama, Ryohei

    2014-07-01

    Phase measuring deflectometry is an emerging technique to measure specular complex surface, such as aspherical surface and free-form surface. It is very attractive for its wide dynamic range of vertical scale and application range. Because it is a gradient based surface profilometry, we have to integrate the measured data to get surface shape. It can be cause of low accuracy. On the other hand, interferometry is accurate and well-known method for precision shape measurement. In interferometry, the original measured data is phase of interference signal, which directly shows the surface shape of the target. However interferometry is too precise to measure aspherical surface, free-form surface and usual surface in common industry. To assure the accuracy in ultra-precision measurement, reliability is the most important thing. Reliability can be kept by cross-checking. Then I will propose measuring method using both interferometer and deflectometry for reliable shape measurement. In this concept, global shape is measured using deflectometry and local shape around flat area is measured using interferometry. The result of deflectometry is global and precise. But it include ambiguity due to slope integration. In interferometry, only a small area can be measured, which is almost parallel to the reference surface. But it is accurate and reliable. To combine both results, it should be global, precise and reliable measurement. I will present the concept of combination of interferometry and deflectometry and some preliminary experimental results.

  20. Measurement of tidal current fields with SRTM along track interferometry

    NASA Astrophysics Data System (ADS)

    Runge, H.; Breit, H.; Eineder, M.; Flament, P.; Romeiser, R.

    2003-04-01

    Although the Shuttle Radar Topography Mission (SRTM, http://www.dfd.dlr.de/srtm/) SAR interferometer was designed to deliver Digital Elevation Models from across track interferometry it turned out that it contained also an Along Track Interferometer (ATI). The paper describes how the ATI can be used to determine the velocity of moving ground objects. These may be cars, trains and ships but the focus of the paper is on the measurement of fast tidal ocean surface currents. The big advantage of the SAR-ATI method over buoys is that the measurement covers a large area and "images" of surface currents can be obtained.The advatage over the well established altimeter measurements is the much higher geometrical resolution and that it works close to coasts and in river outflows. Finally, the advantages over coastal radars is that a spaceborne system can deliver data from round the world. In the paper the results from two test sites, near Brest in France and in the Dutch Waddenzee, will be presented. Comparisons of the SRTM current fields with available current models of these areas show both a very good agreement. The ATI-method will be used in future SAR missions like TerraSAR-X to provide high resolution current maps from many interesting parts of the world.

  1. Continuous subsurface velocity measurement with coda wave interferometry

    NASA Astrophysics Data System (ADS)

    Wang, Baoshan; Zhu, Ping; Chen, Yong; Niu, Fenglin; Wang, Bin

    2008-12-01

    A 1-month field experiment was conducted near Kunming in Yunnan Province, China, to continuously monitor subsurface velocity variations along different baselines. The experiment site is located 10 km west to the seismically very active Xiaojiang fault zone. An electric hammer was used as a source to generate highly repeatable seismic waves, which were recorded by 5 short-period seismometers deployed at ˜10 m to 1.2 km away from the source. Velocity variation was estimated by using coda wave interferometry technique. The technique measures changes in differential time between the coda and the first arrival, which is in principal insensitive to timing errors. We obtained a fractional velocity perturbation (δv/v) of 10-3 to 10-2 with a precision of 10-4. The measured velocity variation is consistent among different components and stations and appears to well correlate with deep water level. The velocity variation is featured by a long-term linear trend and well-developed daily cycles. The latter is interpreted as the velocity response to the barometric pressure. A multivariate linear regression analysis of the data indicates that the velocity change exhibits a negative correlation with barometric pressure, with a stress sensitivity of 10-6/Pa at the experimental site.

  2. Bolometric Interferometry for Cosmic Microwave Background Polariztion Measurements

    NASA Astrophysics Data System (ADS)

    Malu, Siddharth

    2009-05-01

    CMB studies are now a data-rich field in astrophysics. The power spectrum of CMB is well measured and cosmological models have been characterized and polarization has been detected in the CMB. All results fit well within and are explained well by the inflationary paradigm. But current evidence for inflation is indirect. The next generation of CMB experiments will aim at providing the most direct evidence for inflation through the detection of B-modes in CMB polarization. Despite improvements in experimental techniques, it is as yet unclear what configuration and approach a CMB polarization experiment should adopt, in view of lack of information about polarization foregrounds and instrument systematic effects. We describe a novel approach to these measurements, called bolometric interferometry, which avoids many of the systematic errors found in imaging systems. In particular, we describe a prototype, the Millimeter-wave Bolometric Interferometer (MBI). We present a few promising approaches from our collaboration (BRAIN/MBI) and discuss plans for feasibility studies for detecting CMB polarization foregrounds and signals with adding interferometers.

  3. Novel dispersion tolerant interferometry method for accurate measurements of displacement

    NASA Astrophysics Data System (ADS)

    Bradu, Adrian; Maria, Michael; Leick, Lasse; Podoleanu, Adrian G.

    2015-05-01

    We demonstrate that the recently proposed master-slave interferometry method is able to provide true dispersion free depth profiles in a spectrometer-based set-up that can be used for accurate displacement measurements in sensing and optical coherence tomography. The proposed technique is based on correlating the channelled spectra produced by the linear camera in the spectrometer with previously recorded masks. As such technique is not based on Fourier transformations (FT), it does not require any resampling of data and is immune to any amounts of dispersion left unbalanced in the system. In order to prove the tolerance of technique to dispersion, different lengths of optical fiber are used in the interferometer to introduce dispersion and it is demonstrated that neither the sensitivity profile versus optical path difference (OPD) nor the depth resolution are affected. In opposition, it is shown that the classical FT based methods using calibrated data provide less accurate optical path length measurements and exhibit a quicker decays of sensitivity with OPD.

  4. Frequency-scanning interferometry for dynamic absolute distance measurement using Kalman filter.

    PubMed

    Tao, Long; Liu, Zhigang; Zhang, Weibo; Zhou, Yangli

    2014-12-15

    We propose a frequency-scanning interferometry using the Kalman filtering technique for dynamic absolute distance measurement. Frequency-scanning interferometry only uses a single tunable laser driven by a triangle waveform signal for forward and backward optical frequency scanning. The absolute distance and moving speed of a target can be estimated by the present input measurement of frequency-scanning interferometry and the previously calculated state based on the Kalman filter algorithm. This method not only compensates for movement errors in conventional frequency-scanning interferometry, but also achieves high-precision and low-complexity dynamic measurements. Experimental results of dynamic measurements under static state, vibration and one-dimensional movement are presented. PMID:25503050

  5. Shape measurements of microscopic objects using computational shear interferometry

    NASA Astrophysics Data System (ADS)

    Agour, Mostafa; Falldorf, Claas; Bergmann, Ralf B.

    2016-03-01

    We present an efficient and less time consuming implementation of Computational Shear Interferometry (CoSI) by applying a smoothness on the assigned wave field. The method is used to recover the three dimensional form of a micro injection molded part from a set of shear measurements. For this purpose, six shear experiments have been recorded with the shears varying in orientation and magnitude. Varying the shears orientation and magnitude is applied using a setup consisting of a 4f filter with a reflective phase-only spatial light modulator (SLM) in the corresponding Fourier plane. The SLM is used as an electronic diffraction grating with a blazed structure. Based on the birefringent properties of the SLM two orthogonally polarized images, one diffracted and one reflected, appear on the camera sensor and produce shear interferograms. The shift between the images depends on the period and the orientation of the blazed grating. From shear interferograms, the phase of light diffracted by the object is reconstructed by CoSI. Thus the height map of the object is determined.

  6. Measurements of the tympanic membrane with digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Muñoz Solís, S.; Mendoza Santoyo, F.; Del Socorro Hernández-Montes, M.

    2011-08-01

    In this paper a digital holographic interferometry (DHI) system with three object-illumination beams is used for the first time to detect and measure micrometer deformations on the surface of a tympanic membrane. Using this optical setup allows all three object displacement components x, y, and z, to be independently calculated. The corresponding deformations are registered using a cw laser in stroboscopic mode and a CCD camera synchronized to the excitation acoustic wave that produces a resonant vibration mode on the tympanic membrane surface. A series of digital holographic interferograms record the displacements undergone by the tympanic membrane and from them full field deformation phase maps are obtained. From the latter it is possible to observe the displacement of the tympanic membrane in response to the sound pressure. The study was performed on the tympanic membrane taken from a post-mortem cat. The results show the feasibility to apply a similar optomechanical arrangement for the study in humans, representing an alternative technique for the study of pathologies in the tympanic membrane.

  7. Quantum Key Distribution Based on Interferometry and Interaction-Free Measurement

    NASA Astrophysics Data System (ADS)

    Li, Yan-Bing; Xu, Sheng-Wei; Wang, Qing-Le; Liu, Fang; Wan, Zong-Jie

    2016-01-01

    We propose a quantum key distribution based on Mach-Zehnder (MZ) interferometry and interaction-free measurement on single photon. The raw key comes from the photons on which MZ interferometry happened. And the interaction-free measurements are used to detect eavesdroppers. The analysis indicates that the protocol is secure, and can prevent some familiar attacks, such as photon number splitting (PNS) attack. This scheme is easy to be realized in current experiments.

  8. Advances in Swept-Wavelength Interferometry for Precision Measurements

    NASA Astrophysics Data System (ADS)

    Moore, Eric D.

    2011-12-01

    Originally developed for radar applications in the 1950s, swept-wavelength interferometry (SWI) at optical wavelengths has been an active area of research for the past thirty years, with applications in fields ranging from fiber optic telecommunications to biomedical imaging. It now forms the basis of several measurement techniques, including optical frequency domain reflectometry (OFDR), swept-source optical coherence tomography (SS-OCT), and frequency-modulated continuous-wave (FMCW) lidar. In this thesis, I present several novel contributions to the field of SWI that include improvements and extensions to the state of the art in SWI for performing precision measurements. The first is a method for accurately monitoring the instantaneous frequency of the tunable source to accommodate nonlinearities in the source tuning characteristics. This work ex- tends the commonly used method incorporating an auxiliary interferometer to the increasingly relevant cases of long interferometer path mismatches and high-speed wavelength tuning. The second contribution enables precision absolute range measurements to within a small fraction of the transform-limited range resolution of the SWI system. This is accomplished through the use of digital filtering in the time domain and phase slope estimation in the frequency domain. Measurements of optical group delay with attosecond-level precision are experimentally demonstrated and applied to measurements of group refractive index and physical thickness. The accuracy of the group refractive index measurement is shown to be on the order of 10-6, while measurements of absolute thicknesses of macroscopic samples are accomplished with accuracy on the order of 10 nm. Furthermore, sub-nanometer uncertainty for relative thickness measurements can be achieved. For the case of crystalline silicon wafers, the achievable uncertainty is on the same order as the Si-Si bond length, opening the door to potential thickness profiling with single atomic

  9. Mode-resolved frequency comb interferometry for high-accuracy long distance measurement

    PubMed Central

    van den Berg, Steven. A.; van Eldik, Sjoerd; Bhattacharya, Nandini

    2015-01-01

    Optical frequency combs have developed into powerful tools for distance metrology. In this paper we demonstrate absolute long distance measurement using a single femtosecond frequency comb laser as a multi-wavelength source. By applying a high-resolution spectrometer based on a virtually imaged phased array, the frequency comb modes are resolved spectrally to the level of an individual mode. Having the frequency comb stabilized against an atomic clock, thousands of accurately known wavelengths are available for interferometry. From the spectrally resolved output of a Michelson interferometer a distance is derived. The presented measurement method combines spectral interferometry, white light interferometry and multi-wavelength interferometry in a single scheme. Comparison with a fringe counting laser interferometer shows an agreement within <10−8 for a distance of 50 m. PMID:26419282

  10. Mode-resolved frequency comb interferometry for high-accuracy long distance measurement

    NASA Astrophysics Data System (ADS)

    van den Berg, Steven. A.; van Eldik, Sjoerd; Bhattacharya, Nandini

    2015-09-01

    Optical frequency combs have developed into powerful tools for distance metrology. In this paper we demonstrate absolute long distance measurement using a single femtosecond frequency comb laser as a multi-wavelength source. By applying a high-resolution spectrometer based on a virtually imaged phased array, the frequency comb modes are resolved spectrally to the level of an individual mode. Having the frequency comb stabilized against an atomic clock, thousands of accurately known wavelengths are available for interferometry. From the spectrally resolved output of a Michelson interferometer a distance is derived. The presented measurement method combines spectral interferometry, white light interferometry and multi-wavelength interferometry in a single scheme. Comparison with a fringe counting laser interferometer shows an agreement within <10-8 for a distance of 50 m.

  11. Mode-resolved frequency comb interferometry for high-accuracy long distance measurement.

    PubMed

    van den Berg, Steven A; van Eldik, Sjoerd; Bhattacharya, Nandini

    2015-01-01

    Optical frequency combs have developed into powerful tools for distance metrology. In this paper we demonstrate absolute long distance measurement using a single femtosecond frequency comb laser as a multi-wavelength source. By applying a high-resolution spectrometer based on a virtually imaged phased array, the frequency comb modes are resolved spectrally to the level of an individual mode. Having the frequency comb stabilized against an atomic clock, thousands of accurately known wavelengths are available for interferometry. From the spectrally resolved output of a Michelson interferometer a distance is derived. The presented measurement method combines spectral interferometry, white light interferometry and multi-wavelength interferometry in a single scheme. Comparison with a fringe counting laser interferometer shows an agreement within <10(-8) for a distance of 50 m. PMID:26419282

  12. Measurement of micro-V-groove dihedral using white light interferometry

    NASA Astrophysics Data System (ADS)

    Fang, Fengzhou; Zeng, Zhen; Zhang, Xiaodong; Jiang, Lili

    2016-01-01

    This study presents a micro-V-grooves dihedral measurement method using white light interferometry on multiple reflection phenomena. When an optical instrument is used to measure microstructures with steep large gradient faces with high reflection rate, considerable measurement errors caused by multiple scattering or multiple reflecting can be observed. These difficulties have limited the application of white light interferometry in the measurement of microstructures. However, the study has found that the multiple-reflection phenomena can be utilized to measure V-groove dihedral angle. The precision of dihedral measurement is a guarantee of ultra-precise machining of retro-reflection mirrors which requires a non-contact measurement to avoid scratches and surface defects caused by the contact probe. The proposed method is capable of obtaining more accurate surface profile data compared to common white light interferometry. Experimental results verify the method and the consistence between the proposed method and contact mode profilometer.

  13. Water induced geohazards measured with spaceborne interferometry techniques

    NASA Astrophysics Data System (ADS)

    Poncos, V.; Serban, F.; Teleaga, D.; Ciocan, V.; Sorin, M.; Caranda, D.; Zamfirescu, F.; Andrei, M.; Copaescu, S.; Radu, M.; Raduca, V.

    2012-04-01

    Natural and anthropogenic occurrence of groundwater is inducing surficial crustal deformation processes that can be accurately measured with high spatial density from space, regardless of the ground access conditions. The detection of the surface deformation allows uncovering spatial and temporal patterns of subsurface processes such as land subsidence, cave-ins and differential ground settlement related to water content. InSAR measurements combined with ground truth data permit estimation of the mechanical properties of the rocks and the development of models and scenarios to predict disaster events such as cave-ins, landslides and soil liquefaction in the case of an Earthquake. A number of three sites in Romania that suffer of ground instability because of the water component will be presented. The DInSAR, Interferograms Stacking and Persistent Scatterers Interferometry techniques were applied to retrieve as accurate as possible the displacement information. The first studied site is the city of Bucharest; using 7 years of ERS data ground instability was detected on a large area that represents the historical watershed of the Dambovita river. A network of water wells shows that the ground instability is directly proportional to the groundwater depth. The second site is the Ocnele Mari brine extraction area. The exploitation of the Ocnele Mari salt deposit started from the Roman Empire time using the mining technology and from 1954 the salt dissolution technology which involves injecting water into the ground using a well and extracting the brine (water and salt) through another well. The extraction of salt through dissolution led to slow ground subsidence but the flooding and dissolution of the Roman caves led to catastrophic cave-ins and the relocation of an entire village. The water injection technique is still applied and the Roman cave system is an unknown, therefore further catastrophic events are expected. The existing theoretical simulations of the

  14. Differential interferometry for measurement of density fluctuations and fluctuation-induced transport (invited)

    SciTech Connect

    Lin, L.; Ding, W. X.; Brower, D. L.; Bergerson, W. F.; Yates, T. F.

    2010-10-15

    Differential interferometry employs two parallel laser beams with a small spatial offset (less than beam width) and frequency difference (1-2 MHz) using common optics and a single mixer for a heterodyne detection. The differential approach allows measurement of the electron density gradient, its fluctuations, as well as the equilibrium density distribution. This novel interferometry technique is immune to fringe skip errors and is particularly useful in harsh plasma environments. Accurate calibration of the beam spatial offset, accomplished by use of a rotating dielectric wedge, is required to enable broad application of this approach. Differential interferometry has been successfully used on the Madison Symmetric Torus reversed-field pinch plasma to directly measure fluctuation-induced transport along with equilibrium density profile evolution during pellet injection. In addition, by combining differential and conventional interferometry, both linear and nonlinear terms of the electron density fluctuation energy equation can be determined, thereby allowing quantitative investigation of the origin of the density fluctuations. The concept, calibration, and application of differential interferometry are presented.

  15. Deformation measurement of the bone fixed with external fixator using holographic interferometry

    NASA Astrophysics Data System (ADS)

    Kojima, Arata; Ogawa, Ryokei; Izuchi, N.; Yamamoto, Manabu; Nishimoto, T.; Matsumoto, Toshiro

    1991-08-01

    Mechanical properties of tibia fixed with an external fixative device (external fixator) were investigated under some simulated loading conditions. Deformation measurements were performed using double exposure holographic interferometry and real-time holographic interferometry. According to the results of the holographic interferometry, strains on the fixation pins and rods were also measured using strain gauges. The results showed that, with most types of external fixator, dislocations of both fractured ends were mainly caused by decrease in strength of the fixation pins. With increase in strength of fixation pins, angular deformation of the rod was more obvious. Increase in the strength of the rod was not always effective in decreasing dislocation of both fractured ends. Changes in bracing technique with marked change in rigidity of external fixator were useful to decrease dislocation of both fractured ends.

  16. Heisenberg-limited interferometry with pair coherent states and parity measurements

    SciTech Connect

    Gerry, Christopher C.; Mimih, Jihane

    2010-07-15

    After reviewing parity-measurement-based interferometry with twin Fock states, which allows for supersensitivity (Heisenberg limited) and super-resolution, we consider interferometry with two different superpositions of twin Fock states, namely, two-mode squeezed vacuum states and pair coherent states. This study is motivated by the experimental challenge of producing twin Fock states on opposite sides of a beam splitter. We find that input two-mode squeezed states, while allowing for Heisenberg-limited sensitivity, do not yield super-resolutions, whereas both are possible with input pair coherent states.

  17. Measurements of liquid surface fluctuations at sub-shot-noise levels with Michelson interferometry.

    PubMed

    Mitsui, Takahisa; Aoki, Kenichiro

    2013-04-01

    Surface fluctuation spectra of liquids are measured to unprecedented precision, down to 3 orders of magnitude below the shot-noise level using averaged correlations of interferometry measurements. This allows us to investigate the limits in our current theoretical understanding of these phenomena. The spectrum derived from hydrodynamical considerations agrees well with the observed results for water. However, for oil, deviations are seen at high frequencies (>/~1 MHz), perhaps indicating its more complex underlying physics. The measurements are made possible by dualizing the Michelson interferometry measurements and employing the averaged correlation of signals, in which the shot noise is statistically reduced. The method works in the presence of the quantum noise of a coherent state of light. The optical part of the experimental setup is essentially the same as that of Michelson interferometry so that the method can be applied when Michelson interferometry can be used. Furthermore, the measurement method requires a relatively low light power and a short time so that it has a wide range of applicability. PMID:23679425

  18. Measurements of liquid surface fluctuations at sub-shot-noise levels with Michelson interferometry

    NASA Astrophysics Data System (ADS)

    Mitsui, Takahisa; Aoki, Kenichiro

    2013-04-01

    Surface fluctuation spectra of liquids are measured to unprecedented precision, down to 3 orders of magnitude below the shot-noise level using averaged correlations of interferometry measurements. This allows us to investigate the limits in our current theoretical understanding of these phenomena. The spectrum derived from hydrodynamical considerations agrees well with the observed results for water. However, for oil, deviations are seen at high frequencies (≳1 MHz), perhaps indicating its more complex underlying physics. The measurements are made possible by dualizing the Michelson interferometry measurements and employing the averaged correlation of signals, in which the shot noise is statistically reduced. The method works in the presence of the quantum noise of a coherent state of light. The optical part of the experimental setup is essentially the same as that of Michelson interferometry so that the method can be applied when Michelson interferometry can be used. Furthermore, the measurement method requires a relatively low light power and a short time so that it has a wide range of applicability.

  19. Measurement of surface profile in vibrating environment with instantaneous phase shifting interferometry

    NASA Astrophysics Data System (ADS)

    Sivakumar, N. R.; Tan, B.; Venkatakrishnan, K.

    2006-01-01

    In-process measurement has been the requirement of the precision industries, but due to vibrations while manufacturing, in-process measurement has been difficult to achieve. There is little work on in-process measurement using phase shifting interferometry, as phase shifting is extremely sensitive to vibrations. In this work, the advantage of the developed non-mechanical and instantaneous phase shifting interferometry is felt while measuring surface profile of large flat surfaces under vibrating conditions which can be extended for in-process measurement of surface profile. A near common path optical configuration is achieved and the effect of the environment is reduced. Moreover, the measurement of phase is instantaneous which increases the versatility of this technique for measuring vibrating objects. Profile measurements were carried out on a smooth mirror surface excited with vibrations of different frequencies and the technique was found to be immune to vibrations of up to 1000 Hz.

  20. Measurement of complex refractive index of human blood by low-coherence interferometry

    NASA Astrophysics Data System (ADS)

    Jedrzejewska-Szczerska, M.

    2013-10-01

    In this article, the usefulness of the optical technique for measurements of blood complex refractive index has been examined. Measurement of optical properties of human blood is difficult to perform because of its nonuniform nature. However, results of my investigation have shown the usefulness of low-coherence interferometry for measurement complex refractive index of human blood. Furthermore, mathematical analysis of spectrum of measured signal have made possible to determined relationship between complex refractive index and hematocrit level in human blood.

  1. Large step structure measurement by using white light interferometry based on adaptive scanning

    NASA Astrophysics Data System (ADS)

    Bian, Yan; Guo, Tong; Li, Feng; Wang, Siming; Fu, Xing; Hu, Xiaotang

    2013-01-01

    As an important measuring technique, white light scanning interferometry can realize non-contact, fast and high accurate measurement. However, when measuring the large step structure, the white light scanning interferometry has the problems of long time consumption and low signal utilization. In this paper, a kind of adaptive scanning technique is proposed to measure the large step structure to improve its efficiency. This technique can be realized in two ways-the pre-configuration mode and the auto-focusing mode. During the scanning process, the image collection is limited within the coherence area, and in other positions, the motion is speeded up. The adaptive scanning is driven by the nano-measuring machine (NMM) which reaches nanometer accuracy and is controlled by the measurement software. The testing result of 100μm step height shows that the adaptive scanning can improve the measuring efficiency dramatically compared with conventional fixed-step scanning and it keeps the same high accuracy.

  2. Effect of Refractive Index Variation on Two-Wavelength Interferometry for Fluid Measurements

    NASA Technical Reports Server (NTRS)

    Mercer, Carolyn R.

    1998-01-01

    Two wavelength interferometry can in principle be used to measure changes in both temperature and concentration in a fluid, but measurement errors may be large if the fluid dispersion is small. This paper quantifies the effects of uncertainties in dn/dT and dn/dC on the measured temperature and concentration when using the simple expression dn = (dn/dT)dT + (dn/dC)dC. For the data analyzed here, ammonium chloride in water from -5 to 10(exp infinity) C over a concentration range of 2-14% and for wavelengths 514.5 and 633 nm, it is shown that the gradients must be known to within 0.015% to produce a modest 10% uncertainty in the measured temperature and concentration. These results show that real care must be taken to ensure the accuracy of refractive index gradients when using two wavelength interferometry for the simultaneous measurement of temperature and concentration.

  3. Actively stabilized optical fiber interferometry technique for online/in-process surface measurement

    SciTech Connect

    Wang Kaiwei; Martin, Haydn; Jiang Xiangqian

    2008-02-15

    In this paper, we report the recent progress in optical-beam scanning fiber interferometry for potential online nanoscale surface measurement based on the previous research. It attempts to generate a robust and miniature measurement device for future development into a multiprobe array measurement system. In this research, both fiber-optic-interferometry and the wavelength-division-multiplexing techniques have been used, so that the optical probe and the optical interferometer are well spaced and fast surface scanning can be carried out, allowing flexibility for online measurement. In addition, this system provides a self-reference signal to stabilize the optical detection with high common-mode noise suppression by adopting an active phase tracking and stabilization technique. Low-frequency noise was significantly reduced compared with unstabilized result. The measurement of a sample surface shows an attained repeatability of 3.3 nm.

  4. Development of a Hybrid Atomic Force Microscopic Measurement System Combined with White Light Scanning Interferometry

    PubMed Central

    Guo, Tong; Wang, Siming; Dorantes-Gonzalez, Dante J.; Chen, Jinping; Fu, Xing; Hu, Xiaotang

    2012-01-01

    A hybrid atomic force microscopic (AFM) measurement system combined with white light scanning interferometry for micro/nanometer dimensional measurement is developed. The system is based on a high precision large-range positioning platform with nanometer accuracy on which a white light scanning interferometric module and an AFM head are built. A compact AFM head is developed using a self-sensing tuning fork probe. The head need no external optical sensors to detect the deflection of the cantilever, which saves room on the head, and it can be directly fixed under an optical microscopic interferometric system. To enhance the system’s dynamic response, the frequency modulation (FM) mode is adopted for the AFM head. The measuring data can be traceable through three laser interferometers in the system. The lateral scanning range can reach 25 mm × 25 mm by using a large-range positioning platform. A hybrid method combining AFM and white light scanning interferometry is proposed to improve the AFM measurement efficiency. In this method, the sample is measured firstly by white light scanning interferometry to get an overall coarse morphology, and then, further measured with higher resolution by AFM. Several measuring experiments on standard samples demonstrate the system’s good measurement performance and feasibility of the hybrid measurement method. PMID:22368463

  5. Development of a hybrid atomic force microscopic measurement system combined with white light scanning interferometry.

    PubMed

    Guo, Tong; Wang, Siming; Dorantes-Gonzalez, Dante J; Chen, Jinping; Fu, Xing; Hu, Xiaotang

    2012-01-01

    A hybrid atomic force microscopic (AFM) measurement system combined with white light scanning interferometry for micro/nanometer dimensional measurement is developed. The system is based on a high precision large-range positioning platform with nanometer accuracy on which a white light scanning interferometric module and an AFM head are built. A compact AFM head is developed using a self-sensing tuning fork probe. The head need no external optical sensors to detect the deflection of the cantilever, which saves room on the head, and it can be directly fixed under an optical microscopic interferometric system. To enhance the system's dynamic response, the frequency modulation (FM) mode is adopted for the AFM head. The measuring data can be traceable through three laser interferometers in the system. The lateral scanning range can reach 25 mm × 25 mm by using a large-range positioning platform. A hybrid method combining AFM and white light scanning interferometry is proposed to improve the AFM measurement efficiency. In this method, the sample is measured firstly by white light scanning interferometry to get an overall coarse morphology, and then, further measured with higher resolution by AFM. Several measuring experiments on standard samples demonstrate the system's good measurement performance and feasibility of the hybrid measurement method. PMID:22368463

  6. Study on a multi-delay spectral interferometry for stellar radial velocity measurement

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Jiang, Haijiao; Tang, Jin; Ji, Hangxin; Zhu, Yongtian; Wang, Liang

    2014-08-01

    High accuracy radial velocity measurement isn't only one of the most important methods for detecting earth-like Exoplanets, but also one of the main developing fields of astronomical observation technologies in future. Externally dispersed interferometry (EDI) generates a kind of particular interference spectrum through combining a fixed-delay interferometer with a medium-resolution spectrograph. It effectively enhances radial velocity measuring accuracy by several times. Another further study on multi-delay interferometry was gradually developed after observation success with only a fixed-delay, and its relative instrumentation makes more impressive performance in near Infrared band. Multi-delay is capable of giving wider coverage from low to high frequency in Fourier field so that gives a higher accuracy in radial velocity measurement. To study on this new technology and verify its feasibility at Guo Shoujing telescope (LAMOST), an experimental instrumentation with single fixed-delay named MESSI has been built and tested at our lab. Another experimental study on multi-delay spectral interferometry given here is being done as well. Basically, this multi-delay experimental system is designed in according to the similar instrument named TEDI at Palomar observatory and the preliminary test result of MESSI. Due to existence of LAMOST spectrograph at lab, a multi-delay interferometer design actually dominates our work. It's generally composed of three parts, respectively science optics, phase-stabilizing optics and delay-calibrating optics. To switch different fixed delays smoothly during observation, the delay-calibrating optics is possibly useful to get high repeatability during switching motion through polychromatic interferometry. Although this metrology is based on white light interferometry in theory, it's different that integrates all of interference signals independently obtained by different monochromatic light in order to avoid dispersion error caused by

  7. A comparison of electronic heterodyne moire deflectometry and electronic heterodyne holographic interferometry for flow measurements

    NASA Technical Reports Server (NTRS)

    Decker, A. J.; Stricker, J.

    1985-01-01

    Electronic heterodyne moire deflectometry and electronic heterodyne holographic interferometry are compared as methods for the accurate measurement of refractive index and density change distributions of phase objects. Experimental results are presented to show that the two methods have comparable accuracy for measuring the first derivative of the interferometric fringe shift. The phase object for the measurements is a large crystal of KD*P, whose refractive index distribution can be changed accurately and repeatably for the comparison. Although the refractive index change causes only about one interferometric fringe shift over the entire crystal, the derivative shows considerable detail for the comparison. As electronic phase measurement methods, both methods are very accurate and are intrinsically compatible with computer controlled readout and data processing. Heterodyne moire is relatively inexpensive and has high variable sensitivity. Heterodyne holographic interferometry is better developed, and can be used with poor quality optical access to the experiment.

  8. A comparison of electronic heterodyne moire deflectometry and electronic heterodyne holographic interferometry for flow measurements

    NASA Technical Reports Server (NTRS)

    Decker, A. J.; Stricker, J.

    1985-01-01

    Electronic heterodyne moire deflectometry and electronic heterodyne holographic interferometry are compared as methods for the accurate measurement of refractive index and density change distributions of phase objects. Experimental results are presented to show that the two methods have comparable accuracy for measuring the first derivative of the interferometric fringe shift. The phase object for the measurements is a large crystal of KD P, whose refractive index distribution can be changed accurately and repeatably for the comparison. Although the refractive index change causes only about one interferometric fringe shift over the entire crystal, the derivative shows considerable detail for the comparison. As electronic phase measurement methods, both methods are very accurate and are intrinsically compatible with computer controlled readout and data processing. Heterodyne moire is relatively inexpensive and has high variable sensitivity. Heterodyne holographic interferometry is better developed, and can be used with poor quality optical access to the experiment.

  9. A combined system for measurements of high-speed flow by interferometry, schlieren and shadowgraph

    NASA Astrophysics Data System (ADS)

    Gregory-Smith, D. G.; Senior, P.; Gilchrist, A. R.

    1990-05-01

    Details are given of a system for making measurements of a jet flow using interferometry, schlieren or shadowgraph. The system is relatively inexpensive and should be generally applicable for any high-speed flows where density gradients are significant. Particular features of the system are the ease of conversion between modes of operation, the stability of the arrangement, and the solution of vibration problems. A computerized technique for analysis of interferograms is described and the results compare well with independent measurements.

  10. Detection techniques in low-coherence interferometry and their impact on overall measurement accuracy.

    PubMed

    Pikálek, Tomáš; Fořt, Tomáš; Buchta, Zdeněk

    2014-12-20

    This paper deals with interference fringe center detection techniques used in low-coherence interferometry for contactless 3D inspection of macroscopic objects. It presents a complex analysis of several frequently used detection techniques and shows their impact on the measurement accuracy. The analysis compares those techniques in terms of computational complexity, measurement accuracy, and resistance to optical dispersion caused by wedge-shaped optical components. PMID:25608195

  11. Time-resolved spatial phase measurements with 2-dimensional spectral interferometry

    NASA Astrophysics Data System (ADS)

    Childress, Colby; Planchon, Thomas; Amir, Wafa; Squier, Jeff A.; Durfee, Charles G.

    2007-03-01

    We are using 2-dimensional spectral interferometry for sensitive measurements of spatial phase distortions. The reference pulse and the time-delayed probe pulse are coincident on an imaging spectrometer, yielding spectral and spatial phase information. This technique offers the potential of higher sensitivity than traditional spatial interferometry since there are many fringes of data for each spatial point. We illustrate this technique with measurements of the thermal lensing profile in a cryogenically cooled Ti:sapphire amplifier crystal that is pumped by tens of watts of power from four frequency-doubled Nd:YLF lasers running at 1 kHz. By adjusting the relative delay of the probe and reference pulses, we characterize the thermal transients during and after the pump pulses. We compare the measured transient thermal profiles with those calculated with a finite-element model.

  12. Depth-resolved whole-field displacement measurement using wavelength scanning interferometry

    NASA Astrophysics Data System (ADS)

    Ruiz, Pablo D.; Zhou, Yanzhou; Huntley, Jonathan M.; Wildman, Ricky D.

    2004-07-01

    We describe a technique for measuring depth-resolved displacement fields within a three-dimensional (3D) scattering medium based on wavelength scanning interferometry. Sequences of two-dimensional interferograms are recorded whilst the wavelength of the laser is tuned at a constant rate. Fourier transformation of the resulting 3D intensity distribution along the time axis reconstructs the scattering potential within the medium, and changes in the 3D phase distribution measured between two separate scans provide one component of the 3D displacement field. The technique is illustrated with a proof-of-principle experiment involving two independently controlled reflecting surfaces. Advantages over the corresponding method based on low-coherence interferometry include a depth range unlimited by mechanical scanning devices, and immunity from fringe contrast reduction when imaging through dispersive media.

  13. Depth-resolved whole-field displacement measurement by wavelength-scanning electronic speckle pattern interferometry

    NASA Astrophysics Data System (ADS)

    Ruiz, Pablo D.; Huntley, Jonathan M.; Wildman, Ricky D.

    2005-07-01

    We show, for the first time to our knowledge, how wavelength-scanning interferometry can be used to measure depth-resolved displacement fields through semitransparent scattering surfaces. Temporal sequences of speckle interferograms are recorded while the wavelength of the laser is tuned at a constant rate. Fourier transformation of the resultant three-dimensional (3-D) intensity distribution along the time axis reconstructs the scattering potential within the medium, and changes in the 3-D phase distribution measured between two separate scans provide the out-of-plane component of the 3-D displacement field. The principle of the technique is explained in detail and illustrated with a proof-of-principle experiment involving two independently tilted semitransparent scattering surfaces. Results are validated by standard two-beam electronic speckle pattern interferometry.

  14. Dynamical measurement of refractive index distribution using digital holographic interferometry based on total internal reflection.

    PubMed

    Zhang, Jiwei; Di, Jianglei; Li, Ying; Xi, Teli; Zhao, Jianlin

    2015-10-19

    We present a method for dynamically measuring the refractive index distribution in a large range based on the combination of digital holographic interferometry and total internal reflection. A series of holograms, carrying the index information of mixed liquids adhered on a total reflection prism surface, are recorded with CCD during the diffusion process. Phase shift differences of the reflected light are reconstructed exploiting the principle of double-exposure holographic interferometry. According to the relationship between the reflection phase shift difference and the liquid index, two dimensional index distributions can be directly figured out, assuming that the index of air near the prism surface is constant. The proposed method can also be applied to measure the index of solid media and monitor the index variation during some chemical reaction processes. PMID:26480394

  15. Measurement of absolute optical thickness distribution of a mask-glass by wavelength tuning interferometry

    NASA Astrophysics Data System (ADS)

    Hibino, Kenichi; Yangjin, Kim; Bitou, Youichi; Ohsawa, Sonko; Sugita, Naohiko; Mitsuishi, Mamoru

    2008-08-01

    The surface flatness and the uniformity in thickness and refractive index of a mask-blank glass have been requested in semiconductor industry. The absolute optical thickness of a mask-blank glass of seven-inch square and 3mm thickness was measured by three-surface interferometry in a wavelength tuning Fizeau interferometer. Wavelength-tuning interferometry can separate in frequency space the three interference signals of the surface shape and the optical thickness. The wavelength of a tunable laser diode source was scanned linearly from 632 nm to 642 nm and a CCD detector recorded two thousand interference images. The number of phase variation of the interference fringes during the wavelength scanning was counted by a temporal discrete Fourier transform. The initial and final phases of the interferograms before and after the scanning were measured by a phase shifting technique with fine tunings of the wavelengths at 632 nm and 642 nm. The optical thickness defined by the group refractive index at the central wavelength of 337 nm can be measured by this technique. Experimental results show that the cross talk in multiple-surface interferometry caused a systematic error of 2.0 microns in the measured optical thickness.

  16. Strain measurements using Fizzeau interferometry and photo-diode sensor in composite structures

    NASA Technical Reports Server (NTRS)

    Syed, Hazari I.; Balister, Raymond L.

    1990-01-01

    A system is presented which allows the measurement of very small changes of strain in real time and can be applied to the design of stable space structures. The Fizzeau interferometry technique is employed in conjunction with a tube dilatometer to generate a fringe pattern that expands and contracts with temperature variations. A photodiode array transforms the bulls eye fringes to video signals which can be analyzed to determine the strain in structural elements such as tubes.

  17. Simultaneous density and magnetic field fluctuation measurements by far-infrared interferometry and polarimetry in MST

    SciTech Connect

    Yates, T. F.; Ding, W. X.; Carter, T. A.; Brower, D. L.

    2008-10-15

    Fluctuations are expected to play an important role in anomalous particle, momentum, and energy transport for magnetic confinement devices. Magnetic and density fluctuations are simultaneously measured using a high-speed laser-based Faraday rotation-interferometry system with a bandwidth of 500 kHz and 8 cm chord spacing. Density fluctuation and magnetic fluctuation profiles are obtained by using a newly developed fitting procedure.

  18. Systematic comparison between line integrated densities measured with interferometry and polarimetry at JET

    SciTech Connect

    Brombin, M.; Zilli, E.; Giudicotti, L.; Boboc, A.; Collaboration: JET-EFDA Contributors

    2009-06-15

    A systematic comparison between the line integrated electron density derived from interferometry and polarimetry at JET has been carried out. For the first time the reliability of the measurements of the Cotton-Mouton effect has been analyzed for a wide range of main plasma parameters and the possibility to evaluate the electron density directly from polarimetric data has been studied. The purpose of this work is to recover the interferometric data with the density derived from the measured Cotton-Mouton effect, when the fringe jump phenomena occur. The results show that the difference between the line integrated electron density from interferometry and polarimetry is with one fringe (1.143x10{sup 19} m{sup -2}) for more than 90% of the cases. It is possible to consider polarimetry as a satisfactory alternative method to interferometry to measure the electron density and it could be used to recover interferometric signal when a fringe jumps occurs, preventing difficulties for the real-time control of many experiments at the JET machine.

  19. Measurement-only topological quantum computation via anyonic interferometry

    SciTech Connect

    Bonderson, Parsa Freedman, Michael Nayak, Chetan

    2009-04-15

    We describe measurement-only topological quantum computation using both projective and interferometrical measurement of topological charge. We demonstrate how anyonic teleportation can be achieved using 'forced measurement' protocols for both types of measurement. Using this, it is shown how topological charge measurements can be used to generate the braiding transformations used in topological quantum computation, and hence that the physical transportation of computational anyons is unnecessary. We give a detailed discussion of the anyonics for implementation of topological quantum computation (particularly, using the measurement-only approach) in fractional quantum Hall systems.

  20. Measuring ocean coherence time with dual-baseline interferometry

    NASA Technical Reports Server (NTRS)

    Carande, Richard E.

    1992-01-01

    Using the Jet Propulsion Laboratory (JPL) Airborne Synthetic Aperture Radar (AIRSAR) interferometer, measurements of the ocean coherence time at L and C band can be made at high spatial resolution. Fundamental to this measurement is the ability to image the ocean interferometrically at two different time-lags, or baselines. By modifying the operating procedure of the existing two antenna interferometer, a technique was developed make these measurements. L band coherence times are measured and presented.

  1. Characterization of drying paint coatings by dynamic speckle and holographic interferometry measurements.

    PubMed

    Budini, N; Mulone, C; Balducci, N; Vincitorio, F M; López, A J; Ramil, A

    2016-06-10

    In this work we implemented dynamic speckle and holographic interferometry techniques to characterize the drying process of solvent-based paint coatings. We propose a simple way to estimate drying time by measuring speckle activity and incrementally fitting experimental data through standard regression algorithms. This allowed us to predict drying time after about 20-30 min of paint application, which is fast compared to usual times required to reach the so-called tack-free state (≈2  h). In turn, we used holographic interferometry to map small thickness variations in the coating surface during drying. We also demonstrate that results obtained from both techniques correlate with each other, which allows us to improve the accuracy of the drying time estimation. PMID:27409029

  2. Measurement of Poisson's ratio of nonmetallic materials by laser holographic interferometry

    NASA Astrophysics Data System (ADS)

    Zhu, Jian T.

    1991-12-01

    By means of the off-axis collimated plane wave coherent light arrangement and a loading device by pure bending, Poisson's ratio values of CFRP (carbon fiber-reinforced plactics plates, lay-up 0 degree(s), 90 degree(s)), GFRP (glass fiber-reinforced plactics plates, radial direction) and PMMA (polymethyl methacrylate, x, y direction) have been measured. In virtue of this study, the ministry standard for the Ministry of Aeronautical Industry (Testing method for the measurement of Poisson's ratio of non-metallic by laser holographic interferometry) has been published. The measurement process is fast and simple. The measuring results are reliable and accurate.

  3. Simultaneous differential measurement of a magnetic-field gradient by atom interferometry using double fountains

    SciTech Connect

    Hu Zhongkun; Duan Xiaochun; Zhou Minkang; Sun Buliang; Zhao Jinbo; Huang Maomao; Luo Jun

    2011-07-15

    Precisely measuring the magnetic-field gradient within a vacuum chamber is important for many precision experiments and can be realized by atom interferometry using magnetically sensitive sublevels at different times to make a differential measurement, which had been demonstrated in our previous work. In this paper, we demonstrate a differential method to measure the magnetic-field gradient by means of two simultaneously operated atom interferometers using double atomic fountains. By virtue of this simultaneous differential measurement to reject common-mode noise, the resolution can be improved by one order of magnitude for about a 1000-s integration time.

  4. Optical feedback interferometry for measuring dynamic stress deformation of beams

    NASA Astrophysics Data System (ADS)

    Atashkhooei, Reza; Azcona, Francisco; Royo, Santiago; Espert, Lluis Gil

    2012-06-01

    An optical feedback interferometer has been used as a sensor for measuring the deformation of the beams under dynamic loading. The compactness, non-contact nature, high accuracy (below half wavelength of the laser) and the cost-effectiveness of this sensor makes it a suitable choice for material deformation measurements. A general procedure of the measurement is described in detail, including the proposed solution to deal with the speckle effect which appears when large deformations are presented. The performance of the proposed sensor has been compared and validated with a commercial contact LVDT sensor showing measurement differences below 20μm (2.9%).

  5. Sub-pixel phase-measuring interferometry with interlace stitching

    NASA Technical Reports Server (NTRS)

    Mooney, James T.

    2005-01-01

    Measurement of mid spatial frequency figure error is critical to large precision optics for missions such as TPF-C. This presentation introduces a technique for increasing the spatial sampling resolution to meet these requirements using conventional video resolution phase-measuring interferometer. Technique involves sub-pixel data shifts, interlaced stitching and PSF deconvolution.

  6. Semiconductor Laser Line-width Measurements for Space Interferometry Applications

    NASA Technical Reports Server (NTRS)

    Dougherty, D.; Guttierrez, R.; Dubovitsky, S.; Forouhar, S.

    1999-01-01

    This work discusses results using the self-heterodyne delay atechnique to measure 1.3 um InP based DFB lasers. We will also address practical issues concerning detection and elimination of back reflections, choice of fiber length and resolution, and measurement of laser 1/f and current supply noise.

  7. Synthetic-wavelength self-mixing interferometry for displacement measurement

    NASA Astrophysics Data System (ADS)

    Chen, Junbao; Zhu, Hongbin; Xia, Wei; Guo, Dongmei; Hao, Hui; Wang, Ming

    2016-06-01

    A simple synthetic-wavelength self-mixing interferometer is proposed for precision displacement measurement. Choosing the frequency difference of the orthogonally polarized dual frequency He-Ne laser appropriately, we introduce synthetic wavelength theory into self-mixing interference principle and demonstrate a feasible optical configuration by simply adjusting the optical design of self-mixing interferometer. The phase difference between the two orthogonally polarized feedback fringes is observed, and the tiny displacement of the object can be measured through the phase change of the synthetic signal. Since the virtual synthetic wavelength is 106 times larger than the operating wavelength, sub-nanometer displacement of the object can be obtained in millimeter criterion measurement without modulation, demodulation and complicated electrical circuits. Experimental results verifies the synthetic wavelength self-mixing interferometer's ability of measuring nanoscale displacement, which provides a potential approach for contactless precision displacement measurement in a number of scientific and industrial applications.

  8. Atom Interferometry Measurements of Static and Dynamic Polarizability

    NASA Astrophysics Data System (ADS)

    Trubko, Raisa; Holmgren, Will; Hromada, Ivan; Ronan, Joe; Cronin, Alex

    2011-10-01

    We report progress towards new measurements of static and dynamic polarizabilities for several atomic species. We use a nanograting Mach-Zehnder atom interferometer with an electric field gradient to observe atomic de Broglie wave phase shifts that are proportional to the electric polarizability. These measurements provide tests of atomic structure calculations that are needed to improve the precision of atomic clocks. We explain the progress and challenges of measuring the dynamic polarizability of potassium, the static polarizability of strontium and ytterbium, and several polarizability ratios (e.g. αNa/αLi) with one part per thousand accuracy.

  9. Non-contact angle measurement based on parallel multiplex laser feedback interferometry

    NASA Astrophysics Data System (ADS)

    Zhang, Song; Tan, Yi-Dong; Zhang, Shu-Lian

    2014-11-01

    We present a novel precise angle measurement scheme based on parallel multiplex laser feedback interferometry (PLFI), which outputs two parallel laser beams and thus their displacement difference reflects the angle variation of the target. Due to its ultrahigh sensitivity to the feedback light, PLFI realizes the direct non-contact measurement of non-cooperative targets. Experimental results show that PLFI has an accuracy of 8″ within a range of 1400″. The yaw of a guide is also measured and the experimental results agree with those of the dual-frequency laser interferometer Agilent 5529A.

  10. Digital holographic interferometry for simultaneous orthogonal radial vibration measurements along rotating shafts

    SciTech Connect

    Tatar, Kourosh; Gren, Per; Lycksam, Henrik

    2008-06-20

    A digital holographic interferometry setup used to measure radial vibrations along a rotating shaft is presented. A continuous Nd:YAG laser and a high-speed digital camera are used for recording the holograms. The shaft was polished optically smooth to avoid speckle noise from the rotating surface. The light reflected from the shaft was directed onto a diffuser which in turn was imaged by the holographic system. Simultaneous measurements with a laser vibrometer were performed at one point and comparisons between the signals showed good agreement. It is shown that different vibration components of a rotating shaft can be simultaneously measured with this technique.

  11. Measurement of intraocular distances in human eyes by using Fourier domain low-coherence interferometry

    NASA Astrophysics Data System (ADS)

    Feng, Liang; Zhu, Lida; Li, Qinghua; Ma, Zhenhe; Wang, Bo; Wang, Yi

    2016-03-01

    We introduce a system for rapidly measuring the intraocular distances of human eyes in vivo with high sensitivity by using Fourier domain low-coherence interferometry. The system mainly consisting of a rapid focus displacement unit and a reference arm which has a variable optical path length. This system is capable of providing a complete biometrical assessment of a human eye in a single measurement procedure, including cornea thickness, anterior chamber depth, lens thickness, and axial length. The system is experimentally verified by measuring the four parameters of a human eye in vivo.

  12. Analysis of Polarizability Measurements Made with Atom Interferometry

    NASA Astrophysics Data System (ADS)

    Gregoire, Maxwell; Brooks, Nathan; Trubko, Raisa; Cronin, Alexander

    2016-07-01

    We present revised measurements of the static electric dipole polarizabilities of K, Rb, and Cs based on atom interferometer experiments presented in [Phys. Rev. A 2015, 92, 052513] but now re-analyzed with new calibrations for the magnitude and geometry of the applied electric field gradient. The resulting polarizability values did not change, but the uncertainties were significantly reduced. Then we interpret several measurements of alkali metal atomic polarizabilities in terms of atomic oscillator strengths $f_{ik}$, Einstein coefficients $A_{ik}$, state lifetimes $\\tau_{k}$, transition dipole matrix elements $D_{ik}$, line strengths $S_{ik}$, and van der Waals $C_6$ coefficients. Finally, we combine atom interferometer measurements of polarizabilities with independent measurements of lifetimes and $C_6$ values in order to quantify the residual contribution to polarizability due to all atomic transitions other than the principal $ns$-$np_J$ transitions for alkali metal atoms.

  13. An analysis of source structure effects in radio interferometry measurements

    NASA Technical Reports Server (NTRS)

    Thomas, J. B.

    1980-01-01

    To begin a study of structure effects, this report presents a theoretical framework, proposes an effective position approach to structure corrections based on brightness distribution measurements, and analyzes examples of analytical and measured brightness distributions. Other topics include the effect of the frequency dependence of a brightness distribution on bandwidth synthesis (BWS) delay, the determination of the absolute location of a measured brightness distribution, and structure effects in dual frequency calibration of charged particle delays. For the 10 measured distributions analyzed, it was found that the structure effect in BWS delay at X-band (3.6 cm) can reach 30 cm, but typically falls in the range of 0 to 5 cm. A trial limit equation that is dependent on visibility was successfully tested against the 10 measured brightness distributions (seven sources). If the validity of this particular equation for an upper limit can be established for nearly all sources, the structure effect in BWS delay could be greatly reduced without supplementary measurements of brightness distributions.

  14. Dispersive qubit measurement by interferometry with parametric amplifiers

    NASA Astrophysics Data System (ADS)

    Barzanjeh, Sh.; DiVincenzo, D. P.; Terhal, B. M.

    2014-10-01

    We perform a detailed analysis of how an amplified interferometer can be used to enhance the quality of a dispersive qubit measurement, such as one performed on a superconducting transmon qubit, using homodyne detection on an amplified microwave signal. Our modeling makes a realistic assessment of what is possible in current circuit-QED experiments; in particular, we take into account the frequency dependence of the qubit-induced phase shift for short microwaves pulses. We compare the possible signal-to-noise ratios obtainable with (single-mode) SU(1,1) interferometers with the current coherent measurement and find a considerable reduction in measurement error probability in an experimentally accessible range of parameters.

  15. Measuring Energy Differences by BEC Interferometry on a Chip

    SciTech Connect

    Baumgaertner, Florian; Sewell, R. J.; Eriksson, S.; Llorente-Garcia, I.; Dingjan, Jos; Cotter, J. P.; Hinds, E. A.

    2010-12-10

    We investigate the use of a Bose-Einstein condensate trapped on an atom chip for making interferometric measurements of small energy differences. We measure and explain the noise in the energy difference of the split condensates, which derives from statistical noise in the number difference. We also consider systematic errors. A leading effect is the variation of the rf magnetic field in the trap with distance from the wires on the chip surface. This can produce energy differences that are comparable with those due to gravity.

  16. Measuring energy differences by BEC interferometry on a chip.

    PubMed

    Baumgärtner, Florian; Sewell, R J; Eriksson, S; Llorente-Garcia, I; Dingjan, Jos; Cotter, J P; Hinds, E A

    2010-12-10

    We investigate the use of a Bose-Einstein condensate trapped on an atom chip for making interferometric measurements of small energy differences. We measure and explain the noise in the energy difference of the split condensates, which derives from statistical noise in the number difference. We also consider systematic errors. A leading effect is the variation of the rf magnetic field in the trap with distance from the wires on the chip surface. This can produce energy differences that are comparable with those due to gravity. PMID:21231523

  17. Density measurements in an expanding flow using holographic interferometry

    NASA Technical Reports Server (NTRS)

    Sharma, Surendra P.; Ruffin, Stephen M.; Meyer, Scott A.; Gillespie, Walter D.; Yates, Leslie A.

    1992-01-01

    A nonequilibrium expansion of nitrogen through a 2-dimensional nozzle of a reflected shock tunnel is investigated with laser holography, time resolved pressure measurements and emission spectroscopy to characterize the flow field for vibrational relaxation measurements. A 2D computation is used to simulate the nozzle flow field. Synthetic holograms are generated using the computed density profiles and are compared with the experimental holograms. Also, using a quasi 1-D approximation, populations for each vibrational level are computed by (1) solving the master equations and (2) using the Landau-Teller formulation. Computational accuracy of both models is assessed against the experimental data.

  18. Interferometry on diffuse surfaces in high-velocity measurements

    NASA Astrophysics Data System (ADS)

    Pronin, A.; Gupta, V.

    1993-08-01

    An interferometer is presented which is capable of measuring the free-surface velocities and displacements of both specular and diffuse surfaces. The setup utilizes a previously used principle of producing a virtual image of one mirror at the same distance from the photodiode as the second mirror of the interferometer, albeit with considerable simplification. It is shown that use of a He-Ne laser of only 5-mW power can produce high contrast displacement fringes from surfaces of materials with nonuniform microstructure, including composites. Substrates of carbon-carbon composites and polycrystalline alumina with nonuniform microstructure on the scale of 5-10 μm, and with peak velocities up to 150 m/s were considered. An experimental strategy which allows one to covert the optical setup to either a velocity or a displacement interferometer is also discussed. It is further shown that use of a fast photodiode and a high-speed digitizer with a 5-ps rise time provides a time resolution of 0.2 ns for recording the displacement fringes, and allows measuring free surface velocities up to 800 m/s. This is demonstrated by measuring such transient surface velocities with rise times of 1 ns on a specular Si surface. In all the experiments reported here, the surface velocities were produced by the reflection of a stress wave, which in turn was generated on the back surface of the substrate, using a Nd:YAG laser pulse.

  19. Two-wavelength method for endoscopic shape measurement by spatial phase-shifting speckle-interferometry.

    PubMed

    Kandulla, Jochen; Kemper, Björn; Knoche, Sabine; von Bally, Gert

    2004-10-10

    A two-wavelength method for endoscopic topography reconstruction is introduced that can be applied to out-of-plane sensitive electronic-speckle-pattern interferometry systems based on rigid endoscope imaging systems. The surface measurement is performed by detection of the phase-difference distribution affected by a change in the applied laser wavelength. Furthermore, the off-axis endoscopic illumination geometry is taken into account by an approximation. Experimental results of the characterization of the endoscopic surface reconstruction technique and the measurement accuracy obtained are described and discussed. Finally, the applicability of the method is demonstrated with results from the topographic reconstruction of a free-form surface. PMID:15508598

  20. Elastohydrodynamic film thickness measurements of artificially produced surface dents and grooves. [using optical interferometry

    NASA Technical Reports Server (NTRS)

    Wedeven, L. D.; Cusano, C.

    1978-01-01

    Elastohydrodynamic (EHD) film thickness measurements using optical interferometry were made of artificially produced dents and grooves under rolling and sliding conditions. These measurements are compared to stylus traces of the dent and groove profiles to determine the local deformation associated with micro-EHD pressure generation. The surface geometry associated with the dents and grooves became intimately involved in the lubrication process itself, creating local pressure variations that substantially deformed the local surface geometry, particularly under sliding conditions. The rolling results implied surface initiated fatigue, and the sliding results showed clearly the EHD surface interactions that must occur prior to scuffing failure.

  1. High-speed deformation measurement using spatially phase-shifted speckle interferometry

    NASA Astrophysics Data System (ADS)

    Beckmann, Tobias; Fratz, Markus; Bertz, Alexander; Carl, Daniel

    2014-02-01

    Electronic speckle pattern interferometry (ESPI) is a powerful technique for differential shape measurement with submicron resolution. Using spatial phase-shifting (SPS), no moving parts are required, allowing frame acquisition rates limited by camera hardware. We present ESPI images of 1 megapixel resolution at 500 fps. Analysis of SPS data involves complex, time-consuming calculations. The graphics processing units found in state-of-the-art personal computers have exceptional parallel processing capabilities, allowing real-time SPS measurements at video frame rates. Deformation analysis at this frame rate can be used to analyze transient phenomena such as transient temperature effects in integrated circuit chips or during material processing.

  2. A dynamic optical measurement system for cryogenic fluids using laser interferometry

    NASA Astrophysics Data System (ADS)

    Zhang, J. H.; Bao, S. R.; Zhang, R. P.; Qiu, L. M.

    2015-12-01

    Dynamic visualization is of great significance in the research of flow conditions and mass transfer process of cryogenic fluids. In this paper, two common ways to measure the concentration of cryogenic fluids are introduced and compared. To improve the real-time monitoring of cryogenic fluid, a non-contact dynamic optical measurement system using laser interferometry is designed, which is sensitive to subtle changes of fluid concentration. A precise and dynamic interference pattern can be obtained using this system. Two-dimensional concentration distribution of the fluid can be calculated from the interference pattern. Detailed calculation process is presented in the paper.

  3. Synthetic Aperture Interferometry: In-Process Measurement of Aspheric Optics

    NASA Astrophysics Data System (ADS)

    Tomlinson, Richard; Coupland, Jeremy M.; Petzing, Jon

    2003-02-01

    A scanning probe consisting of a source and receive fiber pair is used to measure the phase difference between wave fronts scattered from the front and rear surfaces of an aspheric optic. This system can be thought of as a classical interferometer with an aperture synthesized from the data collected along the path of the probe. If the form of either surface is known, the other can be deduced. In contrast with classical interferometers, the method does not need test or null plates and has the potential to be integrated into the manufacturing process.

  4. Diffraction effects in length measurements by laser interferometry.

    PubMed

    Sasso, C P; Massa, E; Mana, G

    2016-03-21

    High-accuracy dimensional measurements by laser interferometers require corrections because of diffraction, which makes the effective fringe-period different from the wavelength of a plane (or spherical) wave λ0. By using a combined X-ray and optical interferometer as a tool to investigate diffraction across a laser beam, we observed wavelength variations as large as 10-8λ0. We show that they originate from the wavefront evolution under paraxial propagation in the presence of wavefront- and intensity-profile perturbations. PMID:27136842

  5. Measuring Diffusion of Liquids by Common-Path Interferometry

    NASA Technical Reports Server (NTRS)

    Rashidnia, Nasser

    2003-01-01

    A method of observing the interdiffusion of a pair of miscible liquids is based on the use of a common-path interferometer (CPI) to measure the spatially varying gradient of the index refraction in the interfacial region in which the interdiffusion takes place. Assuming that the indices of refraction of the two liquids are different and that the gradient of the index of refraction of the liquid is proportional to the gradient in the relative concentrations of either liquid, the diffusivity of the pair of liquids can be calculated from the temporal variation of the spatial variation of the index of refraction. This method yields robust measurements and does not require precise knowledge of the indices of refraction of the pure liquids. Moreover, the CPI instrumentation is compact and is optomechanically robust by virtue of its common- path design. The two liquids are placed in a transparent rectangular parallelepiped test cell. Initially, the interface between the liquids is a horizontal plane, above which lies pure liquid 2 (the less-dense liquid) and below which lies pure liquid 1 (the denser liquid). The subsequent interdiffusion of the liquids gives rise to a gradient of concentration and a corresponding gradient of the index of refraction in a mixing layer. For the purpose of observing the interdiffusion, the test cell is placed in the test section of the CPI, in which a collimated, polarized beam of light from a low-power laser is projected horizontally through a region that contains the mixing layer.

  6. Slope measurement of bent plates using double grating shearing interferometry

    SciTech Connect

    Dhanotia, Jitendra; Prakash, Shashi; Rana, Santosh; Sasaki, Osami

    2011-06-20

    A grating-based shearing interferometeric setup for slope measurement of bent plates has been proposed. The specimen under test is illuminated by a collimated beam from the laser. Light reflected from the specimen passes through two identical holographic gratings placed in tandem. The grating frequency has been so chosen that the diffracted orders from each grating are separated out distinctly. Two first-order beams diffracted from each of the gratings superpose in space. In the resulting interferogram, the fringes due to slope information of the object are visualized. Mathematical formulation for experimental determination of slope values has been undertaken. Validation of the experimental results with theoretical predictions in case of cantilever beam provides good correlation. The main advantage of the technique has been the realization of very compact geometry without the need for spatial filtering arrangement commonly associated with the grating-based techniques used to date.

  7. Laser wakefield excitation and measurement by femtosecond longitudinal interferometry

    SciTech Connect

    Siders, C.W.; Le Blanc, S.P.; Fisher, D.; Tajima, T.; Downer, M.C.; Babine, A.; Stepanov, A.; Sergeev, A.

    1996-04-01

    Plasma density oscillations (Langmuir waves) in the wake of an intense (I{sub peak} {approximately} 3 {times} 10{sup 17}W/cm{sup 2}) laser pulse (100 fs) are measured with ultrafast time resolution using a longitudinal interferometric technique. Phase shifts consistent with large amplitude ({delta}n{sub e}/n{sub e} {approximately} 1) density waves at the electron plasma frequency were observed in a fully tunnel-ionized He plasma, corresponding to longitudinal electric fields of {approximately} 10 GV/m. Strong radial ponderomotive forces enhance the density oscillations. As this technique utilizes a necessary component of any laser-based plasma accelerator, it promises to be a powerful tool for on-line monitoring and control of future plasma-based particle accelerators.

  8. Francis M. Pipkin Award Talk - Precision Measurement with Atom Interferometry

    NASA Astrophysics Data System (ADS)

    Müller, Holger

    2015-05-01

    Atom interferometers are relatives of Young's double-slit experiment that use matter waves. They leverage light-atom interactions to masure fundamental constants, test fundamental symmetries, sense weak fields such as gravity and the gravity gradient, search for elusive ``fifth forces,'' and potentially test properties of antimatter and detect gravitational waves. We will discuss large (multiphoton-) momentum transfer that can enhance sensitivity and accuracy of atom interferometers several thousand fold. We will discuss measuring the fine structure constant to sub-part per billion precision and how it tests the standard model of particle physics. Finally, there has been interest in light bosons as candidates for dark matter and dark energy; atom interferometers have favorable sensitivity in searching for those fields. As a first step, we present our experiment ruling out chameleon fields and a broad class of other theories that would reproduce the observed dark energy density.

  9. Measurement of microresonator frequency comb coherence by spectral interferometry.

    PubMed

    Webb, K E; Jang, J K; Anthony, J; Coen, S; Erkintalo, M; Murdoch, S G

    2016-01-15

    We experimentally investigate the spectral coherence of microresonator optical frequency combs. Specifically, we use a spectral interference method, typically used in the context of supercontinuum generation, to explore the variation of the magnitude of the complex degree of first-order coherence across the full comb bandwidth. We measure the coherence of two different frequency combs and observe wholly different coherence characteristics. In particular, we find that the observed dynamical regimes are similar to the stable and unstable modulation instability regimes reported in previous theoretical studies. Results from numerical simulations are found to be in good agreement with experimental observations. In addition to demonstrating a new technique to assess comb stability, our results provide strong experimental support for previous theoretical analyses. PMID:26766693

  10. Surface measurement of indium tin oxide thin film by wavelength-tuning Fizeau interferometry.

    PubMed

    Kim, Yangjin; Hibino, Kenichi; Sugita, Naohiko; Mitsuishi, Mamoru

    2015-08-10

    Indium-tin oxide (ITO) thin films have been widely used in displays such as liquid crystal displays and touch panels because of their favorable electrical conductivity and optical transparency. The surface shape and thickness of ITO thin films must be precisely measured to improve their reliability and performance. Conventional measurement techniques take single point measurements and require expensive systems. In this paper, we measure the surface shape of an ITO thin film on top of a transparent plate using wavelength-tuning Fizeau interferometry. The surface shape was determined by compensating for the phase error introduced by optical interference from the thin film, which was calculated using the phase and amplitude distributions measured by wavelength-tuning. The proposed measurement method achieved noncontact, large-aperture, and precise measurements of transparent thin films. The surface shape of the sample was experimentally measured to an accuracy of 5.13 nm. PMID:26368388

  11. Surface topographical changes measured by phase-locked interferometry

    NASA Technical Reports Server (NTRS)

    Lauer, J. L.; Fung, S. S.

    1984-01-01

    An electronic optical laser interferometer capable of resolving depth differences of as low as 30 A and planar displacements of 6000 A was constructed to examine surface profiles of bearing surfaces without physical contact. Topological chemical reactivity was determined by applying a drop of dilute alcoholic hydrochloric acid and measuring the profile of the solid surface before and after application of this probe. Scuffed bearing surfaces reacted much faster than virgin ones but that bearing surfaces exposed to lubricants containing an organic chloride reacted much more slowly. The reactivity of stainless steel plates, heated in a nitrogen atmosphere to different temperatures, were examined later at ambient temperature. The change of surface contour as a result of the probe reaction followed Arrhenius-type relation with respect to heat treatment temperature. The contact area of the plate of a ball/plate sliding elastohydrodynamic contact run on trimethylopropane triheptanoate with or without additives was optically profiled periodically. As scuffing was approached, the change of profile within the contact region changed much more rapidly by the acid probe and assumed a constant high value after scuffing. A nonetching metallurgical phase was found in the scuff mark, which was apparently responsible for the high reactivity.

  12. Measurement of elasto-plastic deformations by speckle interferometry

    NASA Astrophysics Data System (ADS)

    Bova, Marco; Bruno, Luigi; Poggialini, Andrea

    2010-09-01

    In the paper the authors present an experimental equipment for elasto-plastic characterization of engineering materials by tensile tests. The stress state is imposed to a dog bone shaped specimen by a testing machine fixed on the optical table and designed for optimizing the performance of a speckle interferometer. All three displacement components are measured by a portable speckle interferometer fed by three laser diodes of 50 mW, by which the deformations of a surface of about 6×8 mm2 can be fully analyzed in details. All the equipment is driven by control electronics designed and realized on purpose, by which it is possible to accurately modify the intensity of the illumination sources, the position of a PZT actuator necessary for applying phase-shifting procedure, and the overall displacement applied to the specimen. The experiments were carried out in National Instrument LabVIEW environment, while the processing of the experimental data in Wolfram Mathematica environment. The paper reports the results of the elasto-plastic characterization of a high strength steel specimen.

  13. Cell volume and plasma membrane osmotic water permeability in epithelial cell layers measured by interferometry.

    PubMed Central

    Farinas, J; Verkman, A S

    1996-01-01

    The development of strategies to measure plasma membrane osmotic water permeability (Pf) in epithelial cells has been motivated by the identification of a family of molecular water channels. A general approach utilizing interferometry to measure cell shape and volume was developed and applied to measure Pf in cell layers. The method is based on the cell volume dependence of optical path length (OPL) for a light beam passing through the cell. The small changes in OPL were measured by interferometry. A mathematical model was developed to relate the interference signal to cell volume changes for cells of arbitrary shape and size. To validate the model, a Mach-Zehnder interference microscope was used to image OPL in an Madin Darby Canine Kidney (MDCK) cell layer and to reconstruct the three-dimensional cell shape (OPL resolution < lambda/25). As predicted by the model, a doubling of cell volume resulted in a change in OPL that was proportional to the difference in refractive indices between water and the extracellular medium. The time course of relative cell volume in response to an osmotic gradient was computed from serial interference images. To measure cell volume without microscopy and image analysis, a Mach-Zehnder interferometer was constructed in which one of two interfering laser beams passed through a flow chamber containing the cell layer. The interference signal in response to an osmotic gradient was analyzed to quantify the time course of relative cell volume. The calculated MDCK cell plasma membrane Pf of 6.1 x 10(-4) cm/s at 24 degrees C agreed with that obtained by interference microscopy and by a total internal reflection fluorescence method. Interferometry was also applied to measure the apical plasma membrane water permeability of intact toad urinary bladder; Pf increased fivefold after forskolin stimulation to 0.04 cm/s at 23 degrees C. These results establish and validate the application of interferometry to quantify cell volume and osmotic water

  14. A laser interferometer for measuring straightness and its position based on heterodyne interferometry

    SciTech Connect

    Chen Benyong; Zhang Enzheng; Yan Liping; Li Chaorong; Tang Wuhua; Feng Qibo

    2009-11-15

    Not only the magnitude but also the position of straightness errors are of concern to users. However, current laser interferometers used for measuring straightness seldom give the relative position of the straightness error. To solve this problem, a laser interferometer for measuring straightness and its position based on heterodyne interferometry is proposed. The optical configuration of the interferometer is designed and the measurement principle is analyzed theoretically. Two experiments were carried out. The first experiment verifies the validity and repeatability of the interferometer by measuring a linear stage. Also, the second one for measuring a flexure-hinge stage demonstrates that the interferometer is capable of nanometer measurement accuracy. These results show that this interferometer has advantages of simultaneously measuring straightness error and the relative position with high precision, and a compact structure.

  15. Distance measurement using frequency scanning interferometry with mode-hoped laser

    NASA Astrophysics Data System (ADS)

    Medhat, M.; Sobee, M.; Hussein, H. M.; Terra, O.

    2016-06-01

    In this paper, frequency scanning interferometry is implemented to measure distances up to 5 m absolutely. The setup consists of a Michelson interferometer, an external cavity tunable diode laser, and an ultra-low expansion (ULE) Fabry-Pérot (FP) cavity to measure the frequency scanning range. The distance is measured by acquiring simultaneously the interference fringes from, the Michelson and the FP interferometers, while scanning the laser frequency. An online fringe processing technique is developed to calculate the distance from the fringe ratio while removing the parts result from the laser mode-hops without significantly affecting the measurement accuracy. This fringe processing method enables accurate distance measurements up to 5 m with measurements repeatability ±3.9×10-6 L. An accurate translation stage is used to find the FP cavity free-spectral-range and therefore allow accurate measurement. Finally, the setup is applied for the short distance calibration of a laser distance meter (LDM).

  16. Linewidth measurement of mid infrared quantum cascade laser by optical feedback interferometry

    NASA Astrophysics Data System (ADS)

    Cardilli, Maria Carmela; Dabbicco, Maurizio; Mezzapesa, Francesco Paolo; Scamarcio, Gaetano

    2016-01-01

    We estimated experimentally the linewidth (0.28 MHz) of a distributed feedback quantum cascade laser emitting at 6.2 μm using optical feedback interferometry. The method is simply based on the analysis of the histogram of laser self-mixing fringe periods measured directly as voltage variation across the laser terminals. We assessed the optimal experimental conditions estimating the influence of the optical feedback strength on the interferometric phase noise and compared our results with those reported using conventional interferometric methods based on the analysis of the frequency noise power spectral density.

  17. Measurement of volume resistivity/conductivity of metallic alloy in inhibited seawater by optical interferometry techniques

    SciTech Connect

    Habib, K.

    2011-03-15

    Optical interferometry techniques were used for the first time to measure the volume resistivity/conductivity of carbon steel samples in seawater with different concentrations of a corrosion inhibitor. In this investigation, the real-time holographic interferometry was carried out to measure the thickness of anodic dissolved layer or the total thickness, U{sub total}, of formed oxide layer of carbon steel samples during the alternating current (ac) impedance of the samples in blank seawater and in 5-20 ppm TROS C-70 inhibited seawater, respectively. In addition, a mathematical model was derived in order to correlate between the ac impedance (resistance) and the surface (orthogonal) displacement of the surface of the samples in solutions. In other words, a proportionality constant [resistivity ({rho}) or conductivity ({sigma})= 1/{rho}] between the determined ac impedance [by electrochemical impedance spectroscopy (EIS) technique] and the orthogonal displacement (by the optical interferometry techniques) was obtained. The value of the resistivity of the carbon steel sample in the blank seawater was found similar to the value of the resistivity of the carbon steel sample air, around 1 x 10{sup -5}{Omega} cm. On the contrary, the measured values of the resistivity of the carbon steel samples were 1.85 x 10{sup 7}, 3.35 x 10{sup 7}, and 1.7 x 10{sup 7}{Omega} cm in 5, 10, and 20 ppm TROS C-70 inhibited seawater solutions, respectively. Furthermore, the determined value range of {rho} of the formed oxide layers, from 1.7 x 10{sup 7} to 3.35 x 10{sup 7}{Omega} cm, is found in a reasonable agreement with the one found in literature for the Fe oxide-hydroxides, i.e., goethite ({alpha}-FeOOH) and for the lepidocrocite ({gamma}-FeOOH), 1 x 10{sup 9}{Omega} cm. The {rho} value of the Fe oxide-hydroxides, 1 x 10{sup 9}{Omega} cm, was found slightly higher than the {rho} value range of the formed oxide layer of the present study. This is because the former value was determined

  18. Techniques and applications of SAR interferometry for ERS-1: Topographic mapping, change detection, and slope measurement

    NASA Technical Reports Server (NTRS)

    Werner, Charles L.; Hensley, Scott; Goldstein, Richard M.; Rosen, Paul A.; Zebker, Howard A.

    1993-01-01

    SAR (Synthetic Aperture Radar) interferometry allows the measurement of high resolution topography of terrain from repeat orbit SAR data sets obtained by the ERS-1 AMI (Active Microwave Instrument). The system parameters which affect the accuracy of the topographic maps are errors in determination of the interferometric baseline, non parallel orbit tracks, decorrelation caused by baseline length, thermal noise, and surface change. Surface change can be observed in the interferograms either through decorrelation of the interferometric phase, or coherent phase shifts caused by locally uniform surface displacements. Phase gradient maps can be derived directly from the complex interferograms and can be transformed into surface slopes mapped onto a geometrically corrected grid.

  19. Mode-shape measurement of piezoelectric plate using temporal speckle pattern interferometry and temporal standard deviation.

    PubMed

    Chang, Ching-Yuan; Ma, Chien-Ching

    2011-11-01

    This study proposes an image processing method to improve the quality of interference fringes in mode-shape measurement using temporal speckle pattern interferometry. A vibrating piezoelectric plate at resonance was investigated, and the full-field optical information was saved as a sequence of images. According to derived statistical properties, an algorithm was developed to remove noise from both the background and disturbance, resulting in high-resolution images of excellent quality. In addition, the resonant frequency and mode shape obtained using the proposed algorithm demonstrate excellent agreement with theoretical results obtained by the finite element method. PMID:22048391

  20. Coda wave interferometry for the measurement of thermally induced ultrasonic velocity variations in CFRP laminates

    NASA Astrophysics Data System (ADS)

    Livings, Richard; Dayal, Vinay; Barnard, Dan

    2016-02-01

    Ultrasonic velocity measurement is a well-established method to measure properties and estimate strength as well as detect and locate damage. Determination of accurate and repeatable ultrasonic wave velocities can be difficult due to the influence of environmental and experimental factors. Diffuse fields created by a multiple scattering environment have been shown to be sensitive to homogeneous strain fields such as those caused by temperature variations, and Coda Wave Interferometry has been used to measure the thermally induced ultrasonic velocity variation in concrete, aluminum, and the Earth's crust. In this work, we analyzed the influence of several parameters of the experimental configuration on the measurement of thermally induced ultrasonic velocity variations in a carbon-fiber reinforced polymer plate. Coda Wave Interferometry was used to determine the relative velocity change between a baseline signal taken at room temperature and the signal taken at various temperatures. The influence of several parameters of the experimental configuration, such as the material type, the receiver aperture size, and fiber orientation on the results of the processing algorithm was evaluated in order to determine the optimal experimental configuration.---This work is supported by the NSF Industry/University Cooperative Research Program of the Center for Nondestructive Evaluation at Iowa State University.

  1. Very-long-baseline-interferometry measurements of planetary orbiters at Mars and Venus

    NASA Technical Reports Server (NTRS)

    Kroger, Peter M.; Folkner, William M.; Iijima, Byron A.; Hildebrand, Claude E.

    1993-01-01

    The first attempts to use radio interferometric techniques to measure the positions of planetary orbiters were made in 1980 with the Viking Mars orbiter and again in 1993 using the Pioneer Venus orbiter. The angular accuracy of these early measurements was on the order of 200 nrad. This work describes more recent very-long baseline interferometry (VLBI) measurements made in 1989 of the Soviet Martian orbiter, Phobos 2, and several measurements made since September of 1990 of the Magellan spacecraft orbiting Venus. Both the Phobos and Magellan measurements recorded data with the Mark 3 VLBI systems located at antennas of NASA's Deep Space Network (DSN). The much wider bandwidth of this recording system and the availability of ionospheric calibrations should allow angular accuracy approaching 5 nrad to be achieved with these measurements.

  2. Ultrafast measurements of optical spectral coherence by single-shot time-stretch interferometry.

    PubMed

    Xu, Yiqing; Wei, Xiaoming; Ren, Zhibo; Wong, Kenneth K Y; Tsia, Kevin K

    2016-01-01

    The palette of laser technology has significantly been enriched by the innovations in ultrafast optical pulse generation. Our knowledge of the complex pulse dynamics, which is often highly nonlinear and stochastic in nature, is however limited by the scarcity of technologies that can measure fast variation/fluctuation of the spectral phase (or coherence) and amplitude in real-time, continuously. To achieve this goal, we demonstrate ultrafast interferometry enabled by optical time-stretch for real- time spectral coherence characterization with microsecond-resolution. Accessing the single-shot interferograms continuously, it further reveals the degree of second-order coherence, defined by the cross-spectral density function, at high speed-a capability absent in any existing spectroscopic measurement tools. As the technique can simultaneously measure both the high-speed variations of spectrally resolved coherence and intensity, time-stretch interferometry could create a new arena for ultrafast pulse characterization, especially favorable for probing and understanding the non-repetitive or stochastic dynamics in real-time. PMID:27295560

  3. Ultrafast measurements of optical spectral coherence by single-shot time-stretch interferometry

    PubMed Central

    Xu, Yiqing; Wei, Xiaoming; Ren, Zhibo; Wong, Kenneth K. Y.; Tsia, Kevin K.

    2016-01-01

    The palette of laser technology has significantly been enriched by the innovations in ultrafast optical pulse generation. Our knowledge of the complex pulse dynamics, which is often highly nonlinear and stochastic in nature, is however limited by the scarcity of technologies that can measure fast variation/fluctuation of the spectral phase (or coherence) and amplitude in real-time, continuously. To achieve this goal, we demonstrate ultrafast interferometry enabled by optical time-stretch for real- time spectral coherence characterization with microsecond-resolution. Accessing the single-shot interferograms continuously, it further reveals the degree of second-order coherence, defined by the cross-spectral density function, at high speed-a capability absent in any existing spectroscopic measurement tools. As the technique can simultaneously measure both the high-speed variations of spectrally resolved coherence and intensity, time-stretch interferometry could create a new arena for ultrafast pulse characterization, especially favorable for probing and understanding the non-repetitive or stochastic dynamics in real-time. PMID:27295560

  4. Ultrafast measurements of optical spectral coherence by single-shot time-stretch interferometry

    NASA Astrophysics Data System (ADS)

    Xu, Yiqing; Wei, Xiaoming; Ren, Zhibo; Wong, Kenneth K. Y.; Tsia, Kevin K.

    2016-06-01

    The palette of laser technology has significantly been enriched by the innovations in ultrafast optical pulse generation. Our knowledge of the complex pulse dynamics, which is often highly nonlinear and stochastic in nature, is however limited by the scarcity of technologies that can measure fast variation/fluctuation of the spectral phase (or coherence) and amplitude in real-time, continuously. To achieve this goal, we demonstrate ultrafast interferometry enabled by optical time-stretch for real- time spectral coherence characterization with microsecond-resolution. Accessing the single-shot interferograms continuously, it further reveals the degree of second-order coherence, defined by the cross-spectral density function, at high speed-a capability absent in any existing spectroscopic measurement tools. As the technique can simultaneously measure both the high-speed variations of spectrally resolved coherence and intensity, time-stretch interferometry could create a new arena for ultrafast pulse characterization, especially favorable for probing and understanding the non-repetitive or stochastic dynamics in real-time.

  5. Development of an angular displacement measurement technique through birefringence heterodyne interferometry.

    PubMed

    Hsieh, Hung-Lin; Lee, Ju-Yi; Chen, Lin-Yu; Yang, Yang

    2016-04-01

    An angular displacement measurement sensor with high resolution for large range measurement is presented. The design concept of the proposed method is based on the birefringence effect and phase detection of heterodyne interferometry. High system symmetry and simple operation can be easily achieved by employing an innovative sandwich optical design for the angular sensor. To evaluate the feasibility and performance of the proposed method, several experiments were performed. The experimental results demonstrate that our angular displacement measurement sensor can achieve a measurement range greater than 26°. Considering the high-frequency noise, the measurement resolution of the system is approximately 1.2° × 10-4. Because of the common-path arrangement, our proposed method can provide superior immunity against environmental disturbances. PMID:27136979

  6. Focal length measurement of a microlens-array by grating shearing interferometry.

    PubMed

    Zhu, Xianchang; Hu, Song; Zhao, Lixin

    2014-10-10

    Based on grating shearing interferometry, a simple technique is introduced for focal length measurements of a microlens-array (MLA). The measurement system is composed of a He-Ne laser, condenser, collimator, the MLA under testing, a Ronchi grating, and CCD sensor. The plane wavefront from the collimator is transformed to a spherical wavefront by the MLA, while the curvature center is at the focus. Interference stripes appear at the overlap between the zero-order and first-order diffractive patterns of the grating and are detected by the CCD sensor. By analyzing the period change of stripes, the focal length is determined after the defocus of the grating is calculated. To validate the feasibility, an experiment is performed. The measurement uncertainty is discussed and measurement accuracy was determined to be 2%. PMID:25322367

  7. Phase shifting interferometry using a spatial light modulator to measure optical thin films.

    PubMed

    Villalobos-Mendoza, Brenda; Granados-Agustín, Fermín S; Aguirre-Aguirre, Daniel; Cornejo-Rodríguez, Alejandro

    2015-09-10

    This work describes a process for measuring thin film steps, using phase shifting interferometry (PSI). The phase shifts are applied only in the region where the thin film steps are located. The phase shift is achieved by displaying different gray levels on a spatial light modulator (SLM Holoeye LC2012) placed in one arm of a Twyman-Green (T-G) interferometer. Before measuring the thin film steps, it was necessary to quantify the phase shifts achieved with this SLM by measuring the fringe shifts in experimental interferograms. The phase shifts observed in the interference patterns were produced by displaying the different gray levels on the SLM one by one, from 0 to 255. The experimental interferograms and the thicknesses of the thin film steps were successfully quantified, proving that this method can be used to measure thin films by applying the PSI method only on the region occupied by them. PMID:26368976

  8. Measurement of aspheric surface combining point diffraction interferometry and annular subaperture stitching

    NASA Astrophysics Data System (ADS)

    Gao, Fen; Jiang, Zhuangde; Zhao, Zixin; Li, Bing

    2015-01-01

    Point diffraction interferometry (PDI) combined with annular subaperture stitching is proposed for ultrahigh-accuracy measurements of aspheric surfaces. By adding an axial movement to the test optics in the PDI system, aspheric surfaces with large departures can be measured with high accuracy by stitching the annular measurement data of different axial positions. We examine the principle of PDI-based annular subaperture stitching and the stitching algorithm. Simulations and experiments demonstrate the feasibility and effectiveness of our proposed method. Our method retains the ultra-high accuracy of PDI while extending the vertical dynamic range of the interferometer, enabling nanometer or even subnanometer accuracy measurements of large-departure rotationally symmetric aspheric surfaces.

  9. Bio-layer interferometry for measuring kinetics of protein-protein interactions and allosteric ligand effects.

    PubMed

    Shah, Naman B; Duncan, Thomas M

    2014-01-01

    We describe the use of Bio-layer Interferometry to study inhibitory interactions of subunit ε with the catalytic complex of Escherichia coli ATP synthase. Bacterial F-type ATP synthase is the target of a new, FDA-approved antibiotic to combat drug-resistant tuberculosis. Understanding bacteria-specific auto-inhibition of ATP synthase by the C-terminal domain of subunit ε could provide a new means to target the enzyme for discovery of antibacterial drugs. The C-terminal domain of ε undergoes a dramatic conformational change when the enzyme transitions between the active and inactive states, and catalytic-site ligands can influence which of ε's conformations is predominant. The assay measures kinetics of ε's binding/dissociation with the catalytic complex, and indirectly measures the shift of enzyme-bound ε to and from the apparently nondissociable inhibitory conformation. The Bio-layer Interferometry signal is not overly sensitive to solution composition, so it can also be used to monitor allosteric effects of catalytic-site ligands on ε's conformational changes. PMID:24638157

  10. Noninvasive Measurement of Acoustic Properties of Fluids Using Ultrasonic Interferometry Technique

    SciTech Connect

    Han, W.; Sinha, D.N.; Springer, K.N.; Lizon, D.C.

    1997-06-15

    A swept-frequency ultrasonic interferometry technique is used for noninvasively determining acoustic properties of fluids inside containers. Measurements over a frequency range 1-15 MHz on six liquid chemicals are presented. Measurements were made with the liquid inside standard rectangular optical glass cells and stainless steel cylindrical shells. A theoretical model based on one-dimensional planar acoustic wave propagation through multi-layered media is employed for the interpretation of the observed resonance (interference) spectrum. Two analytical methods, derived from the transmission model are used for determination of sound speed, sound attenuation coefficient, and density of liquids from the relative amplitude and half-power peak width of the observed resonance peaks. Effects of the container material and geometrical properties, path-length, wall thickness are also studied. This study shows that the interferometry technique and the experimental method developed are capable of accurate determination of sound speed, sound attenuation, and density in fluids completely noninvasively. It is a capable and versatile fluid characterization technique and has many potential NDE applications.

  11. 3-D surface profile measurements of large x-ray synchrotron radiation mirrors using stitching interferometry.

    SciTech Connect

    Assoufid, L.; Bray, M.; Qian, J.; Shu, D.

    2002-09-12

    Stitching interferometry, using small-aperture, high-resolution, phase-measuring interferometry, has been proposed for quite some time now as a metrology technique to obtain 3-dimensional profiles of surfaces of oversized optical components and substrates. The aim of this work is to apply this method to the specific case of long grazing-incidence x-ray mirrors, such as those used in beamlines at synchrotron radiation facilities around the world. Both fabrication and characterization of these mirrors would greatly benefit from this technique because it offers the potential for providing measurements with accuracy and resolution better than those obtained using existing noncontact laser profilers, such as the long trace profiler (LTP). Measurement data can be used as feedback for computer-controlled fabrication processes to correct for possible topography errors. The data can also be used for simulating and predicting mirror performance under realistic conditions. A semiautomated stitching system was built and tested at the X-ray Optics Metrology Laboratory of the Advanced Photon Source at Argonne National Laboratory. The initial objective was to achieve a measurement sensitivity on the order of 1 {micro}rad rms. Preliminary tests on a 1 m-long x-ray mirror showed system repeatability of less than 0.6 {micro}rad rms. This value is comparable to that of a conventional LTP. The measurement accuracy was mostly affected by environmental perturbations and system calibration effects. With a fully automated and improved system (to be built in the near future), we expect to achieve measurement sensitivity on the order of 0.0 {micro}rad rms or better. In this paper, after a brief review of basic principles and general technical difficulties and challenges of the stitching technique, a detailed description of the measurement setup is given and preliminary results obtained with it are analyzed and discussed.

  12. Residual Stress Measurements with Laser Speckle Correlation Interferometry and Local Heat Treating

    SciTech Connect

    Pechersky, M.J.; Miller, R.F.; Vikram, C.S.

    1994-01-06

    A new experimental technique has been devised to measure residual stresses in ductile materials with a combination of laser speckle pattern interferometry and spot heating. The speckle pattern interferometer measures in-plane deformations while the heating provides for very localized stress relief. The residual stresses are determined by the amount of strain that is measured subsequent to the heating and cool-down of the region being interrogated. A simple lumped parameter model is presented to provide a description of the method. This description is followed by presentations of the results of finite element analyses and experimental results with uniaxial test specimens. Excellent agreement between the experiments and the computer analyses were obtained.

  13. Optical-mechanical signatures of cancer cells based on fluctuation profiles measured by interferometry.

    PubMed

    Bishitz, Yael; Gabai, Haniel; Girshovitz, Pinhas; Shaked, Natan T

    2014-08-01

    We propose to establish a cancer biomarker based on the unique optical-mechanical signatures of cancer cells measured in a noncontact, label-free manner by optical interferometry. Using wide-field interferometric phase microscopy (IPM), implemented by a portable, off-axis, common-path and low-coherence interferometric module, we quantitatively measured the time-dependent, nanometer-scale optical thickness fluctuation maps of live cells in vitro. We found that cancer cells fluctuate significantly more than healthy cells, and that metastatic cancer cells fluctuate significantly more than primary cancer cells. Atomic force microscopy (AFM) measurements validated the results. Our study shows the potential of IPM as a simple clinical tool for aiding in diagnosis and monitoring of cancer. PMID:23585163

  14. Surface profile measurement in white-light scanning interferometry using a three-chip color CCD

    SciTech Connect

    Ma Suodong; Quan Chenggen; Zhu Rihong; Tay, Cho Jui; Chen Lei

    2011-05-20

    White-light scanning interferometry (WLSI) is a useful technique to measure surface profile when a test object contains discontinuous structures or microstructures. A black and white CCD camera is usually utilized to capture interferograms, and a series of corresponding algorithms is used to achieve the profile measurement. However, the color information in the interferograms is lost. A novel profile measurement method that uses phase information in different color channels (red-green-blue) of an interferogram obtained using a three-chip color CCD in WLSI is proposed. The phase values are extracted by a windowed Fourier transform algorithm. Simulation and experimental results are presented to demonstrate the validity of the proposed method.

  15. Measurement of basilar membrane motion in the turtle with laser-feedback interferometry

    NASA Astrophysics Data System (ADS)

    O'Neill, Michael P.; Bearden, Alan J.

    1993-09-01

    In mammalian hearing, the frequency-dependent spatial pattern of movement in the basilar membrane (BM) forms the basis of frequency discrimination (tuning). This is not necessarily the case in lower vertebrates; the turtle, for example, has an electrical resonance mechanism in its auditory receptor cells that varies in best frequency from cell-to-cell along the underlying BM. But how much, if any, of the frequency separation by this reptile is done mechanically by its BM? In other animals, vibrational analyses were indirect in that they required the placement of nonphysiological objects on the BM (e.g., the radioactive source of the Mossbaurer technique or the mirror of traditional laser interferometry). Our attempt to find an alternative approach led to the rediscovery of laser-feedback interferometry (LFI), here applied for the first time to vibration analysis in a biological system. LFI is an ideal method to directly measure the nanometer motion (amplitude and phase) of diffuse scattering surfaces such as the BM because of its simple geometry, ease of alignment, and its ability to respond to surfaces with a broad range of reflectances (10-6 to 1). Preliminary LFI investigations of BM motion in the turtle reveal that its BM is broadly tuned and mainly reflects middle ear filter characteristics. No evidence for frequency-selective spatial BM mechanical tuning was found.

  16. Measuring protein-protein and protein-nucleic Acid interactions by biolayer interferometry.

    PubMed

    Sultana, Azmiri; Lee, Jeffrey E

    2015-01-01

    Biolayer interferometry (BLI) is a simple, optical dip-and-read system useful for measuring interactions between proteins, peptides, nucleic acids, small molecules, and/or lipids in real time. In BLI, a biomolecular bait is immobilized on a matrix at the tip of a fiber-optic sensor. The binding between the immobilized ligand and another molecule in an analyte solution produces a change in optical thickness at the tip and results in a wavelength shift proportional to binding. BLI provides direct binding affinities and rates of association and dissociation. This unit describes an efficient approach using streptavidin-based BLI to analyze DNA-protein and protein-protein interactions. A quantitative set of equilibrium binding affinities (K(d)) and rates of association and dissociation (k(a)/k(d)) can be measured in minutes using nanomole quantities of sample. PMID:25640894

  17. High sensitivity resonance frequency measurements of individualmicro-cantilevers using fiber optical interferometry

    SciTech Connect

    Duden, Thomas; Radmilovic, Velimir

    2009-03-04

    We describe a setup for the resonance frequency measurement of individual microcantilevers. The setup displays both high spatial selectivity and sensitivity to specimen vibrations by utilizing a tapered uncoated fiber tip. The high sensitivity to specimen vibrations is achieved by the combination of optical Fabry-Perot interferometry and narrow band RF detection. Wave fronts reflected on the specimen and on the fiber tip end face interfere, thus no reference plane on the specimen is needed, as demonstrated with the example of freestanding silicon nitride micro-cantilevers. The resulting system is integrated in a DB-235 dual beam FIB system, thereby allowing the measurement of micro-cantilever responses during observation in SEM mode. The FIB was used to modify the optical fiber tip. At this point of our RF system development, the microcantilevers used to characterize the detector were not modified in situ.

  18. In Situ Frequency Measurement of Inidividual Nanostructures Using Fiber Optical Interferometry

    SciTech Connect

    Duden, Thomas; Duden, Thomas; Radmilovic, Velimir

    2008-07-01

    In this paper we describe a setup for the resonance frequency measurement of nanocantilevers, which displays both high spatial selectivity and sensitivity to specimen vibrations by utilizing a tapered uncoated fiber tip. The spatial selectivity is determined by the tip geometry, the high sensitivity to vibrations stems from interference of wave fronts reflected on the specimen and on the fiber tip itself. No reference plane on the specimen is needed, as demonstrated with the example of a freestanding silicon nitride cantilever. The resulting system is integrated in the DB-235 dual beam FIB system, thus allowing the measurement of sample responses in-situ, during observation in SEM mode. By combining optical interferometry and narrow band RF amplification and detection, we demonstrate an exceptional vibrational sensitivity at high spatial resolution.

  19. Optical Feedback Interferometry for Velocity Measurement of Parallel Liquid-Liquid Flows in a Microchannel.

    PubMed

    Ramírez-Miquet, Evelio E; Perchoux, Julien; Loubière, Karine; Tronche, Clément; Prat, Laurent; Sotolongo-Costa, Oscar

    2016-01-01

    Optical feedback interferometry (OFI) is a compact sensing technique with recent implementation for flow measurements in microchannels. We propose implementing OFI for the analysis at the microscale of multiphase flows starting with the case of parallel flows of two immiscible fluids. The velocity profiles in each phase were measured and the interface location estimated for several operating conditions. To the authors knowledge, this sensing technique is applied here for the first time to multiphase flows. Theoretical profiles issued from a model based on the Couette viscous flow approximation reproduce fairly well the experimental results. The sensing system and the analysis presented here provide a new tool for studying more complex interactions between immiscible fluids (such as liquid droplets flowing in a microchannel). PMID:27527178

  20. Interseismic deformation of the Shahroud fault system (NE Iran) from space-borne radar interferometry measurements

    NASA Astrophysics Data System (ADS)

    Mousavi, Z.; Pathier, E.; Walker, R. T.; Walpersdorf, A.; Tavakoli, F.; Nankali, H.; Sedighi, M.; Doin, M.-P.

    2015-07-01

    The Shahroud fault system is a major active structure in the Alborz range of NE Iran whose slip rate is not well constrained despite its potential high seismic hazard. In order to constrain the slip rate of the eastern Shahroud fault zone, we use space-borne synthetic aperture radar interferometry with both ascending and descending Envisat data to determine the rate of interseismic strain accumulation across the system. We invert the slip rate from surface velocity measurements using a half-space elastic dislocation model. The modeling results are consistent with a left-lateral slip rate of 4.75 ± 0.8 mm/yr on the Abr and Jajarm, strands of the Shahroud fault, with a 10 ± 4 km locking depth. This is in good agreement with the 4-6 mm/yr of left-lateral displacement rate accumulated across the total Shahroud fault system obtained from GPS measurements.

  1. Comparison between x-ray scattering and velocity-interferometry measurements from shocked liquid deuterium.

    PubMed

    Falk, K; Regan, S P; Vorberger, J; Crowley, B J B; Glenzer, S H; Hu, S X; Murphy, C D; Radha, P B; Jephcoat, A P; Wark, J S; Gericke, D O; Gregori, G

    2013-04-01

    The equation of state of light elements is essential to understand the structure of Jovian planets and inertial confinement fusion research. The Omega laser was used to drive a planar shock wave in the cryogenically cooled deuterium, creating warm dense matter conditions. X-ray scattering was used to determine the spectrum near the boundary of the collective and noncollective scattering regimes using a narrow band x-ray source in backscattering geometry. Our scattering spectra are thus sensitive to the individual electron motion as well as the collective plasma behavior and provide a measurement of the electron density, temperature, and ionization state. Our data are consistent with velocity-interferometry measurements previously taken on the same shocked deuterium conditions and presented by K. Falk et al. [High Energy Density Phys. 8, 76 (2012)]. This work presents a comparison of the two diagnostic systems and offers a detailed discussion of challenges encountered. PMID:23679534

  2. The use of holographic interferometry for measurements of temperature in a rectangular heat pipe. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Marn, Jure

    1989-01-01

    Holographic interferometry is a nonintrusive method and as such possesses considerable advantages such as not disturbing the velocity and temperature field by creating obstacles which would alter the flow field. These optical methods have disadvantages as well. Holography, as one of the interferometry methods, retains the accuracy of older methods, and at the same time eliminates the system error of participating components. The holographic interferometry consists of comparing the objective beam with the reference beam and observing the difference in lengths of optical paths, which can be observed during the propagation of the light through a medium with locally varying refractive index. Thus, change in refractive index can be observed as a family of nonintersecting surfaces in space (wave fronts). The object of the investigation was a rectangular heat pipe. The goal was to measure temperatures in the heat pipe, which yields data for computer code or model assessment. The results were obtained by calculating the temperatures by means of finite fringes.

  3. Measuring neoplastic transformation in the hamster cheek pouch using Fourier domain low-coherence interferometry

    NASA Astrophysics Data System (ADS)

    Graf, Robert N.; Chen, Xiaoxin; Brown, William; Wax, Adam

    2008-02-01

    Fourier Domain Low Coherence Interferometry (fLCI) is a promising technique which combines the depth resolution of low coherence interferometry with the sensitivity of light scattering spectroscopy for probing the health of epithelial tissue layers. Our new fLCI system configuration utilizes a white light Xe arc lamp source and a 4-f interferometer which re-images light scattered from the sample onto the detection plane. The system employs an imaging spectrometer at the detection plane to acquire depth resolved profiles from 252 adjacent spatial points without the need for any scanning. The limited spatial coherence of the light source requires the resolution of adjacent spatial points for the generation of depth information. Depth-resolved spectral information is recovered by performing a short-time Fourier transform on the detected spectra, similar to spectroscopic optical coherence tomography. Wavelength dependent variations in scattering intensity are analyzed as a function of depth to obtain information about the neoplastic transformation of the probed cells. Previous studies have demonstrated fLCI as an excellent technique for probing the scatterer morphology of simple phantoms and of in vitro cancer cell monolayers. We now seek to assess the ability of the new fLCI system to measure the health of subsurface tissue layers using the hamster cheek pouch model. Seven hamsters will have one cheek pouch treated with the known carcinogen DMBA. At the conclusion of the 24 week treatment period the animals will be anesthetized and the cheek pouches will be extracted. We will use the fLCI optical system to measure the neoplastic transformation of the in situ subsurface tissue layers in both the normal and DMBA-treated cheek pouches. Traditional histological analysis will be used to verify the fLCI measurements. We expect our results to establish the feasibility of fLCI to distinguish between healthy and dysplastic epithelial tissues in the hamster cheek pouch.

  4. Surface deformation and coherence measurements of Kilauea Volcano, Hawaii, from SIR C radar interferometry

    NASA Astrophysics Data System (ADS)

    Rosen, P. A.; Hensley, S.; Zebker, H. A.; Webb, F. H.; Fielding, E. J.

    1996-10-01

    The shuttle imaging radar C/X synthetic aperture radar (SIR C/X SAR) radar on board the space shuttle Endeavor imaged Kilauea Volcano, Hawaii, in April and October 1994 for the purpose of measuring active surface deformation by the methods of repeat-pass differential radar interferometry. Observations at 24 cm (L band) and 5.6 cm (C band) wavelengths were reduced to interferograms showing apparent surface deformation over the 6-month interval and over a succession of 1-day intervals in October. A statistically significant local phase signature in the 6-month interferogram is coincident with the Pu'u O'o lava vent. Interpreted as deformation, the signal implies centimeter-scale deflation in an area several kilometers wide surrounding the vent. Peak deflation is roughly 14 cm if the deformation is purely vertical, centered southward of the Pu'u O'o caldera. Delays in the radar signal phase induced by atmospheric refractivity anomalies introduce spurious apparent deformation signatures, at the level of 12 cm peak-to-peak in the radar line-of-sight direction. Though the phase observations are suggestive of the wide-area deformation measured by Global Positioning System (GPS) methods, the atmospheric effects are large enough to limit the interpretation of the result. It is difficult to characterize centimeter-scale deformations spatially distributed over tens of kilometers using differential interferometry without supporting simultaneous, spatially distributed measurements of refractivity along the radar line of sight. Studies of the interferometric correlation of images acquired at different times show that L band is far superior to C band in the vegetated areas, even when the observations are separated by only 1 day. These results imply longer wavelength instruments are more appropriate for studying surfaces by repeat-pass observations.

  5. Measurement of wavefront structure from large aperture optical components by phase shifting interferometry

    SciTech Connect

    Wolfe, C.R.; Lawson, J.K.; Kellam, M.; Maney, R.T.; Demiris, A.

    1995-05-12

    This paper discusses the results of high spatial resolution measurement of the transmitted or reflected wavefront of optical components using phase shifting interferometry with a wavelength of 6328 {angstrom}. The optical components studied range in size from approximately 50 mm {times} 100 mm to 400 mm {times} 750 mm. Wavefront data, in the form of 3-D phase maps, have been obtained for three regimes of scale length: ``micro roughness``, ``mid-spatial scale``, and ``optical figure/curvature.`` Repetitive wavefront structure has been observed with scale lengths from 10 mm to 100 mm. The amplitude of this structure is typically {lambda}/100 to {lambda}/20. Previously unobserved structure has been detected in optical materials and on the surfaces of components. We are using this data to assist in optimizing laser system design, to qualify optical components and fabrication processes under study in our component development program.

  6. Vibration measurement based on electronic speckle pattern interferometry and radial basis function

    NASA Astrophysics Data System (ADS)

    Dai, Xiangjun; Shao, Xinxing; Geng, Zhencen; Yang, Fujun; Jiang, Yijun; He, Xiaoyuan

    2015-11-01

    A method incorporating amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) with radial basis function (RBF) was proposed to investigate vibration characteristics of structures. The vibration patterns were obtained by AF-ESPI. A novel pre-filtering RBF method was presented to improve the quality of patterns. The out-of-plane vibration amplitude was rebuilt after fringe analysis. Ideal pre-filtering widow sizes for the presented RBF were given based on numerical experiments. For validation, an aluminum circular plate with fixed boundary was determined and compared with FEM, confirming the effectiveness of the proposed method. Finally, vibration characteristics of sandwich panels with honeycomb core were measured. The influence of presence of a pre-notch at different location was also investigated.

  7. Spatial-Heterodyne Interferometry For Reflection And Transm Ission (Shirt) Measurements

    DOEpatents

    Hanson, Gregory R [Clinton, TN; Bingham, Philip R [Knoxville, TN; Tobin, Ken W [Harriman, TN

    2006-02-14

    Systems and methods are described for spatial-heterodyne interferometry for reflection and transmission (SHIRT) measurements. A method includes digitally recording a first spatially-heterodyned hologram using a first reference beam and a first object beam; digitally recording a second spatially-heterodyned hologram using a second reference beam and a second object beam; Fourier analyzing the digitally recorded first spatially-heterodyned hologram to define a first analyzed image; Fourier analyzing the digitally recorded second spatially-heterodyned hologram to define a second analyzed image; digitally filtering the first analyzed image to define a first result; and digitally filtering the second analyzed image to define a second result; performing a first inverse Fourier transform on the first result, and performing a second inverse Fourier transform on the second result. The first object beam is transmitted through an object that is at least partially translucent, and the second object beam is reflected from the object.

  8. Measuring In-Plane Displacements with Variable Sensitivity Using Diffractive Optic Interferometry

    NASA Technical Reports Server (NTRS)

    Shepherd, Robert L.; Gilbert, John A.; Cole, Helen J.; Ashley, Paul R.

    1998-01-01

    This paper introduces a method called diffractive optic interferometry (DOI) which allows in-plane displacement components to be measured with variable sensitivity. DOI relies on binary optical elements fabricated as phase-type Dammann gratings which produce multiple diffraction orders of nearly equal intensity. Sensitivity is varied by combining the different wavefronts produced by a conjugate pair of these binary optical elements; a transmission element is used to produce several illumination beams while a reflective element, replicated on the surface of a specimen, provides the reference for the undeformed state. The steps taken to design and fabricate these binary optical elements are described. The specimen grating is characterized, and tested on a disk subjected to diametrical compression. Overall, the results are excellent, with experimental data agreeing to within a few percent of the theoretical predictions.

  9. Synthetic Aperture Radar Interferometry

    NASA Technical Reports Server (NTRS)

    Rosen, P. A.; Hensley, S.; Joughin, I. R.; Li, F.; Madsen, S. N.; Rodriguez, E.; Goldstein, R. M.

    1998-01-01

    Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristics of the surface. This paper reviews the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering.

  10. LISA Long-Arm Interferometry

    NASA Technical Reports Server (NTRS)

    Thorpe, James I.

    2009-01-01

    An overview of LISA Long-Arm Interferometry is presented. The contents include: 1) LISA Interferometry; 2) Constellation Design; 3) Telescope Design; 4) Constellation Acquisition; 5) Mechanisms; 6) Optical Bench Design; 7) Phase Measurement Subsystem; 8) Phasemeter Demonstration; 9) Time Delay Interferometry; 10) TDI Limitations; 11) Active Frequency Stabilization; 12) Spacecraft Level Stabilization; 13) Arm-Locking; and 14) Embarassment of Riches.

  11. Mobile very long baseline interferometry and Global Positioning System measurement of vertical crustal motion

    NASA Technical Reports Server (NTRS)

    Kroger, Peter M.; Davidson, John M.; Gardner, Elaine C.

    1986-01-01

    Mobile Very Long Base Interferometry (VLBI) and Global Positioning System (GPS) geodetic measurements have many error sources in common. Calibration of the effects of water vapor on signal transmission through the atmosphere, however, remains the primary limitation to the accuracy of vertical crustal motion measurements made by either technique. The two primary methods of water vapor calibration currently in use for mobile VLBI baseline measurements were evaluated: radiometric measurements of the sky brightness near the 22 GHz emission line of free water molecules and surface meteorological measurements used as input to an atmospheric model. Based upon a limited set of 9 baselines, it is shown that calibrating VLBI data with water vapor radiometer measurements provides a significantly better fit to the theoretical decay model than calibrating the same data with surface meteorological measurements. The effect of estimating a systematic error in the surface meteorological calibration is shown to improve the consistency of the vertical baseline components obtained by the two calibration methods. A detailed error model for the vertical baseline components obtained indicates current mobile VLBI technology should allow accuracies of order 3 cm with WVR calibration and 10 cm when surface meteorological calibration is used.

  12. Highly sensitive displacement measurement based on spectral interferometry and Vernier effect

    NASA Astrophysics Data System (ADS)

    Militky, J.; Kadulova, M.; Hlubina, P.

    2016-05-01

    A highly sensitive measurement of the displacement of an interferometer mirror based on spectral interferometry and Vernier effect is proposed and demonstrated. The displacement measurement employs two interferometers in tandem, an interferometer represented by a combination of a polarizer, a birefrigent quartz crystal and an analyzer, and a Michelson interferometer. In the setup the Vernier effect is generated and the resultant channeled spectrum is with the envelope which shifts with the displacement of the interferometer mirror. We analyze the new measurement method theoretically and show that the sensitivity of the displacement measurement based on the wavelength interrogation is substantially increased in comparison to a standard method with a Michelson interferometer. We also demonstrate the realization of the measurement setup in which the position of the interferometer mirror is controlled via a closed-loop piezo positioning system. Experimental results show that the displacement measurement can reach a sensitivity of 264 nm/μm, which is substantially increased in comparison to -34 nm/μm reached for a standard measurement.

  13. Effects of wall temperature on skin-friction measurements by oil-film interferometry

    NASA Astrophysics Data System (ADS)

    Bottini, H.; Kurita, M.; Iijima, H.; Fukagata, K.

    2015-10-01

    Wind-tunnel skin-friction measurements with thin-oil-film interferometry have been taken on an aluminum sample to investigate the effects of wall temperature on the accuracy of the technique. The sample has been flush-mounted onto a flat plate with an electric heater at its bottom and mirror-smooth temperature-sensitive paint sprayed on its top. The heater has varied the sample temperature from ambient to 328 K, and the paint has permitted wall temperature measurements on the same area of the skin-friction measurements and during the same test. The measured wall temperatures have been used to calculate the correct oil viscosities, and these viscosities and the constant nominal viscosity at 298 K have been used to calculate two different sets of skin-friction coefficients. These sets have been compared to each other and with theoretical values. This comparison shows that the effects of wall temperature on the accuracy of skin-friction measurements are sensible, and more so as wall temperature differs from 298 K. Nonetheless, they are effectively neutralized by the use of wall temperature measurements in combination with the correct oil viscosity-temperature law. In this regard, the special temperature-sensitive paint developed for this study shows advantages with respect to more traditional wall temperature measurement techniques.

  14. Label-free measurement of microbicidal gel thickness using low-coherence interferometry

    NASA Astrophysics Data System (ADS)

    Braun, Kelly E.; Boyer, Jeffrey D.; Henderson, Marcus H.; Katz, David F.; Wax, Adam

    2006-03-01

    Spectral-domain low-coherence interferometry (LCI) was used to measure the thickness of microbicidal gels applied to a cylindrical calibration test socket. Microbicides are topical formulations containing active ingredients targeted to inhibit specific pathogens that are currently under development for application to the epithelial lining of the lower female reproductive tract to combat sexually transmitted infections such as HIV. Understanding the deployment and drug delivery of these formulations is vital to maximizing their effectiveness. Previously, in vivo measurements of microbicidal formulation thickness were assessed using fluorescence measurements of fluorescein-labeled gels via an optical endoscope-based device. Here we present an LCI-based device that measures the thickness of a formulation without the use of any exogenous agents by analyzing the interference pattern generated between the reflections from the front and back surface of the sample. Results are presented that validate the effectiveness and performance of the LCI measurement in a clinically relevant system as compared to an existing fluorescence-based method. The impact of the new LCI-based design on in vivo measurements is discussed.

  15. Comparison of digital holographic interferometry and constant temperature anemometry for measurement of temperature field in fluid

    NASA Astrophysics Data System (ADS)

    Doleček, Roman; Psota, Pavel; Lédl, Vít.; Vít, Tomáś; Dančová, Petra; Kopecký, Václav

    2015-05-01

    The presented paper shows possibility of using digital holographic interferometry (DHI) for temperature field measurement in moving fluids. This method uses a modified Twymann-Green setup having double sensitivity instead of commonly used Mach-Zehnder type of interferometer in order to obtain sufficient phases change of the field. On the other hand this setup is not light efficient as Mach-Zehnder interferometer. For measurement of the fast periodical phenomenon is not necessary to use always the high speed camera. One can consider this field to coherent phenomenon. With employing one digital camera synchronized to periodic field and external triggered one can capture whole period of the phenomenon. However the projections form one viewing direction of asymmetrical temperature field maybe misguided. Hence for sufficient examination of the asymmetrical field one should capture a large number of the phenomenon's projections from different viewing directions. This projections are later used for 3D tomographic reconstruction of the whole temperature field and its time evolution. One of the commonly used method for temperature field measurement in moving fluids is hot wire method - constant temperature anemometry (CTA). In contrast to whole field measurement of DHI it is an invasive point temperature measurement method. One of the limiting factor of using CTA in moving fluids is frequency of temperature changes. This changes should not exceed 1 kHz. This limitation could be overcome by using of optical methods such as DHI. The results of temperature field measurement achieved by both method are compared in the paper.

  16. Theoretical Accuracy of Along-Track Displacement Measurements from Multiple-Aperture Interferometry (MAI)

    PubMed Central

    Jung, Hyung-Sup; Lee, Won-Jin; Zhang, Lei

    2014-01-01

    The measurement of precise along-track displacements has been made with the multiple-aperture interferometry (MAI). The empirical accuracies of the MAI measurements are about 6.3 and 3.57 cm for ERS and ALOS data, respectively. However, the estimated empirical accuracies cannot be generalized to any interferometric pair because they largely depend on the processing parameters and coherence of the used SAR data. A theoretical formula is given to calculate an expected MAI measurement accuracy according to the system and processing parameters and interferometric coherence. In this paper, we have investigated the expected MAI measurement accuracy on the basis of the theoretical formula for the existing X-, C- and L-band satellite SAR systems. The similarity between the expected and empirical MAI measurement accuracies has been tested as well. The expected accuracies of about 2–3 cm and 3–4 cm (γ = 0.8) are calculated for the X- and L-band SAR systems, respectively. For the C-band systems, the expected accuracy of Radarsat-2 ultra-fine is about 3–4 cm and that of Sentinel-1 IW is about 27 cm (γ = 0.8). The results indicate that the expected MAI measurement accuracy of a given interferometric pair can be easily calculated by using the theoretical formula. PMID:25251408

  17. Theoretical accuracy of along-track displacement measurements from multiple-aperture interferometry (MAI).

    PubMed

    Jung, Hyung-Sup; Lee, Won-Jin; Zhang, Lei

    2014-01-01

    The measurement of precise along-track displacements has been made with the multiple-aperture interferometry (MAI). The empirical accuracies of the MAI measurements are about 6.3 and 3.57 cm for ERS and ALOS data, respectively. However, the estimated empirical accuracies cannot be generalized to any interferometric pair because they largely depend on the processing parameters and coherence of the used SAR data. A theoretical formula is given to calculate an expected MAI measurement accuracy according to the system and processing parameters and interferometric coherence. In this paper, we have investigated the expected MAI measurement accuracy on the basis of the theoretical formula for the existing X-, C- and L-band satellite SAR systems. The similarity between the expected and empirical MAI measurement accuracies has been tested as well. The expected accuracies of about 2-3 cm and 3-4 cm (γ = 0.8) are calculated for the X- and L-band SAR systems, respectively. For the C-band systems, the expected accuracy of Radarsat-2 ultra-fine is about 3-4 cm and that of Sentinel-1 IW is about 27 cm (γ = 0.8). The results indicate that the expected MAI measurement accuracy of a given interferometric pair can be easily calculated by using the theoretical formula. PMID:25251408

  18. Projection Moire Interferometry for Rotorcraft Applications: Deformation Measurements of Active Twist Rotor Blades

    NASA Technical Reports Server (NTRS)

    Fleming, Gary A.; Soto, Hector L.; South, Bruce W.

    2002-01-01

    Projection Moire Interferometry (PMI) has been used during wind tunnel tests to obtain azimuthally dependent blade bending and twist measurements for a 4-bladed Active Twist Rotor (ATR) system in simulated forward flight. The ATR concept offers a means to reduce rotor vibratory loads and noise by using piezoelectric active fiber composite actuators embedded in the blade structure to twist each blade as they rotate throughout the rotor azimuth. The twist imparted on the blades for blade control causes significant changes in blade loading, resulting in complex blade deformation consisting of coupled bending and twist. Measurement of this blade deformation is critical in understanding the overall behavior of the ATR system and the physical mechanisms causing the reduction in rotor loads and noise. PMI is a non-contacting, video-based optical measurement technique capable of obtaining spatially continuous structural deformation measurements over the entire object surface within the PMI system field-of-view. When applied to rotorcraft testing, PMI can be used to measure the azimuth-dependent blade bending and twist along the full span of the rotor blade. This paper presents the PMI technique as applied to rotorcraft testing, and provides results obtained during the ATR tests demonstrating the PMI system performance. PMI measurements acquired at select blade actuation conditions generating minimum and maximum rotor loads are provided to explore the interrelationship between rotor loads, blade bending, and twist.

  19. Ground Deformation Measurement with SAR Interferometry - Exupéry Project WP2 Space Based Observations

    NASA Astrophysics Data System (ADS)

    Cong, Xiaoying; Eineder, Michael; Minet, Christian

    2010-05-01

    As one of major natural hazards volcanic unrest and volcanic eruption are gaining more attention nowadays. The Exupéry project aimed at setting-up an Early Response System (VFRS) for volcanic activity was funded by the German Federal Ministry of Education and Research. Within Work Package 2 'Space Based Observations' SAR interferometry is used for monitoring the ground deformation. In comparison with conventional monitoring techniques like GPS the surface changes can be directly detected by using 2 SAR images from different acquisition times and an external DEM. Persistent scatterer SAR interferometry (PSI) method is applied by using a stack of interferograms with common master image. Instead of whole SAR scene only the coherent scatterers during whole acquisition duration are selected and its phase measurements are used to estimate modelled parameters such as deformation velocity, DEM error and atmospheric distortions. In mountainous area backscatterers are decorrelated during the time because of vegetation. To ensure the coherence corner reflector (CR) is used to get stable backscattering. To test the whole system a campaign was carried out during April to August 2009. Two CRs were installed for TerraSAR-X satellite on the test site Lagoa do Fogo volcano. During the campaign 11 strip-map scenes were gathered consequently. Post-processed interferograms as well as the coherence maps were delivered to database center in Hannover and would be published in project website. Time series analysis with coherent scatterers from the stacking was applied in order to detect complex deformation from mountainous area. The CRs were successfully detected in SAR image and will be used as reference points in PSI processing. At the end the interferograms computed from different wavelengths will be compared in this area.

  20. Measuring Crustal Deformation Caused by the Nepal (Gorkha) Earthquake Using ALOS-2 SAR Interferometry

    NASA Astrophysics Data System (ADS)

    Morishita, Y.; Kobayashi, T.; Yarai, H.

    2015-12-01

    A huge earthquake (Mw 7.8, USGS) occurred on 25 April, 2015 in Nepal, followed by the largest aftershock (Mw 7.3, USGS) on 12 May. We applied an InSAR technique to detect crustal deformation caused by the earthquakes using L-band SAR data acquired by ALOS-2. One of the advantages of ALOS-2 over ALOS is ScanSAR interferometry. Beam synchronization, which is a critical factor for ScanSAR interferometry, is always tuned among ALOS-2 observations. While a width of 350 km is covered by a ScanSAR acquisition, the provided data is divided into five swaths with each width of 70 km. Adjacent swaths have an overlapping area with a width of several kilometers, where interferometric phases for two swaths are basically comparable. We processed each swath independently. Preliminary interferograms are contaminated by noises with long wavelength, which makes it difficult to measure the amount of the crustal deformation accurately. We reduce the noises by following steps. First, pseudo reference points with no displacement are put at intervals of 40-100 km outside of the possible deforming area. The differential phase at the points are assumed to be due to the noises. The curved surface of the noises is estimated by smoothly interpolating the differential phase at the points. Note that the pseudo reference points should be located in a high coherence area where the phases can be unwrapped. Furthermore the points in the overlapping area between adjacent swaths allow to preserve consistency of the phases between adjacent swaths. The interferograms show the clear and detailed crustal deformation (published on http://www.gsi.go.jp/cais/topic150429-index-e.html). The maximum of a quasi up-down component of the deformation estimated from the interferograms with different beam directions reaches over 1.4 m uplift at 20 km northeast from Kathmandu and 0.6 m subsidence at a northern part of the deforming area.

  1. Depth-resolved measurement of ocular fundus pulsations by low-coherence tissue interferometry

    NASA Astrophysics Data System (ADS)

    Dragostinoff, Nikolaus; Werkmeister, René M.; Gröschl, Martin; Schmetterer, Leopold

    2009-09-01

    A device that allows for the measurement of ocular fundus pulsations at preselected axial positions of a subject's eye is presented. Unlike previously presented systems, which only allow for observation of the strongest reflecting retinal layer, our system enables the measurement of fundus pulsations at a preselected ocular layer. For this purpose the sample is illuminated by light of low temporal coherence. The layer is then selected by positioning one mirror of a Michelson interferometer according to the depth of the layer. The device contains a length measurement system based on partial coherence interferometry and a line scan charge-coupled device camera for recording and online inspection of the fringe system. In-vivo measurements in healthy humans are performed as proof of principle. The algorithms used for enhancing the recorded images are briefly introduced. The contrast of the observed interference pattern is evaluated for different positions of the measurement mirror and at various distances from the front surface of the cornea. The applications of such a system may be wide, including assessment of eye elongation during myopia development and blood-flow-related changes in intraocular volume.

  2. Tympanic membrane contour measurement with two source positions in digital holographic interferometry

    PubMed Central

    Solís, Silvino M.; Hernández-Montes, María del S.; Santoyo, Fernando M.

    2012-01-01

    The data acquisition from the shape of an object is a must to complete its quantitative displacement measurement analysis. Over the past years whole field of view optical non-invasive testing has been widely used in many areas, from industrial ones to, for instance, biomedical research topics. To measure the surface contour from the tympanic membrane (TM) of ex-vivo cats digital holographic interferometry (DHI) is used in combination with a two-illumination positions method: the shape is directly measured from the phase change between two source positions by means of a digital Fourier transform method. The TM shape data in conjunction with its displacement data renders a complete and accurate description of the TM deformation, a feature that no doubt will serve to better comprehend the hearing process. Acquiring knowledge from the tissue shape indicates a mechanical behavior and, indirectly, an alteration in the physiological structure due to middle ear diseases or damages in the tissue that can deteriorate sound transmission. The TM shape contour was successfully measured by using two source positions within DHI showing that the TM has a conical shape. Its maximum depth was found to be 2 mm, considering the umbo as the reference point with respect to the TM annulus plane, where the setup is arranged in such a manner that it is capable of measuring a height of up to 7 mm. PMID:23243570

  3. Tympanic membrane contour measurement with two source positions in digital holographic interferometry.

    PubMed

    Solís, Silvino M; Hernández-Montes, María Del S; Santoyo, Fernando M

    2012-12-01

    The data acquisition from the shape of an object is a must to complete its quantitative displacement measurement analysis. Over the past years whole field of view optical non-invasive testing has been widely used in many areas, from industrial ones to, for instance, biomedical research topics. To measure the surface contour from the tympanic membrane (TM) of ex-vivo cats digital holographic interferometry (DHI) is used in combination with a two-illumination positions method: the shape is directly measured from the phase change between two source positions by means of a digital Fourier transform method. The TM shape data in conjunction with its displacement data renders a complete and accurate description of the TM deformation, a feature that no doubt will serve to better comprehend the hearing process. Acquiring knowledge from the tissue shape indicates a mechanical behavior and, indirectly, an alteration in the physiological structure due to middle ear diseases or damages in the tissue that can deteriorate sound transmission. The TM shape contour was successfully measured by using two source positions within DHI showing that the TM has a conical shape. Its maximum depth was found to be 2 mm, considering the umbo as the reference point with respect to the TM annulus plane, where the setup is arranged in such a manner that it is capable of measuring a height of up to 7 mm. PMID:23243570

  4. Transient Measurements Under Simulated Mantle Conditions - Simultaneous DTF-Ultrasonic Interferometry, X-Radiography, XRD

    NASA Astrophysics Data System (ADS)

    Mueller, H. J.; Schilling, F. R.; Lathe, C.; Wunder, B.

    2004-12-01

    The interpretation of seismic data from the Earth's deep interior requires measurements of the physical properties of Earth materials under experimental simulated mantle conditions. Elastic wave velocity measurement by ultrasonic interferometry is an important tool for the determination of the elastic properties in multi-anvil devices. Whereas the classical sweep method is very time-consuming, the ultrasonic data transfer function technique (DTF), simultaneously generating all the frequencies used in the experiment, first described by Li et al. (2002), requires just few seconds to save the response of the system. The success of the technique substantially depends on the excitation function and the resolution used for saving the DTF (Mueller et al., 2004a). Background discussion as well as high pressure AƒA_A,A¿A,A 1/2 high temperature results demonstrate how to optimize the technique. All Ultrasonic interferometry allows highly precise travel time measurement at a sample enclosed in a high-pressure multi-anvil device. But under high pressure conditions the influence of sample deformation on the frequencies for destructive and constructive interference used for the evaluation of the elastic properties might be stronger than that from the shift of the elastic moduli. Consequently ultrasonic interferometry requires the exact sample length measurement under in situ conditions. X-ray imaging using brillant synchrotron radiation, called X-radiography, produces grey-scale images of the sample under in situ conditions by converting the X-ray image to an optical one by a CE-YAG-crystal. Saving the optical image by a CCD-camera after redirection by a mirrow, also requires few seconds. To derive the sample length, the different brightness of sample, buffer rod and reflector at the electronic image is evaluated (Mueller et al., 2004b). Contrary to XRD measurements, imaging the sample by X-rays requires a beam diameter larger than the sample length. Therefore the fixed

  5. EOS determination through microscopy- interferometry measurements: A low symmetry energetic materials case study

    NASA Astrophysics Data System (ADS)

    Stavrou, Elissaios; Zaug, Joseph; Crowhurst, Jonathan; Bastea, Sorin; Armstrong, Mike

    2015-03-01

    Measuring equation of state (EOS) of solid specimens under pressure usually involves the determination of the primitive cell volume using x-ray diffraction (XRD) measurements. However, in the case of low symmetry (e.g. triclinic) materials with twining features and large primitive cells, this can be problematic and ambiguous. In order to address this issue we examine the possibility of a direct approach which is based on measuring the surface area and thickness with microscopy and optical interferometry respectively. To test the validity of this approach applied to a crystalline material, we first compared our results from Triamino-Trinitrobenzene (TATB, SG P-1) with the published EOS, as determined with XRD measurements, by Stevens et al. [1]. A near perfect match between the two sets of data has been observed. We also present the results of our study on the energetic material 5-nitro-2,4-dihydro-1,2,4,-triazol-3-one (a-NTO) which crystallizes as a four-component twin [2] with triclinic symmetry. No high-pressure XRD data have been published on a-NTO, probably due to its highly complex crystal structure, making this technique a viable way to probe the cold compression EOS of such compounds. Work performed by the U.S. Department of Energy jointly by Lawrence Livermore National Laboratory; Contract DE-AC52-07NA27344.

  6. Measurement of air refractive index fluctuation based on interferometry with two different reference cavity lengths.

    PubMed

    Chen, Qianghua; Luo, Huifu; Wang, Sumei; Wang, Feng; Chen, Xinhua

    2012-09-01

    A measurement method based on interferometry with two different reference cavity lengths is presented and applied in air refractive index measurement in which the two cavity lengths and a laser wavelength are combined to generate two wavelength equivalents of cavity. Corresponding calculation equations are derived, and the optical path configuration is designed, which is inspired by the traditional synthetic wavelength method. Theoretical analyses indicate that the measurement uncertainty of the determined index of refraction is about 2.3×10(-8), which is mainly affected by the length precision of the long vacuum cavity and the ellipticity of polarization components of the dual-frequency laser, and the range of nonambiguity is 3.0×10(-5), which is decided by the length difference of the two cavities. Experiment results show that the accuracy of air refractive index measurement is better than 5.0×10(-8) when the laboratory conditions changes slowly. The merit of the presented method is that the classical refractometry can be also used without evacuation of the gas cavity during the experiment. Furthermore, the application of the traditional synthetic wavelength method may be extended by using the wavelength equivalents of cavity, any value of which can be easily acquired by changing cavity length rather than using actual wavelengths whose number is limited. PMID:22945157

  7. Uncertainty Analysis for Oil-Film Interferometry Skin-Friction Measurement Techniques

    NASA Technical Reports Server (NTRS)

    Naughton, Jonathan W.; Brown, James L.; Merriam, Marshal (Technical Monitor)

    1996-01-01

    Over the past 20 years, the use of oil-film interferometry to measure the skin friction coefficient (C(sub f) = tau/q where tau is the surface shear stress and q is the dynamic pressure) has increased. Different forms of this oil-film technique with various levels of accuracy and ease of use have been successfully applied in a wide range of flows. The method's popularity is growing due to its relative ease of implementation and minimal intrusiveness as well as an increased demand for C(sub f) measurements. Nonetheless, the accuracy of these methods has not been rigorously addressed to date. Most researchers have simply shown that the skin-friction measurements made using these techniques compare favorably with other measurements and theory, most of which are only accurate to within 5-20%. The use of skin-friction data in the design of commercial aircraft, whose drag at cruise is 50% skin-friction drag, and in the validation of computational fluid dynamics programs warrants better uncertainty estimates. Additional information is contained in the original extended abstract.

  8. Study of correlation between overlay and displacement measured by Coherent Gradient Sensing (CGS) interferometry

    NASA Astrophysics Data System (ADS)

    Mileham, Jeffrey; Tanaka, Yasushi; Anberg, Doug; Owen, David M.; Lee, Byoung-Ho; Bouche, Eric

    2016-03-01

    Within the semiconductor lithographic process, alignment control is one of the most critical considerations. In order to realize high device performance, semiconductor technology is approaching the 10 nm design rule, which requires progressively smaller overlay budgets. Simultaneously, structures are expanding in the 3rd dimension, thereby increasing the potential for inter-layer distortion. For these reasons, device patterning is becoming increasingly difficult as the portion of the overlay budget attributed to process-induced variation increases. After lithography, overlay gives valuable feedback to the lithography tool; however overlay measurements typically have limited density, especially at the wafer edge, due to throughput considerations. Moreover, since overlay is measured after lithography, it can only react to, but not predict the process-induced overlay. This study is a joint investigation in a high-volume manufacturing environment of the portion of overlay associated with displacement induced by a single process across many chambers. Displacement measurements are measured by Coherent Gradient Sensing (CGS) interferometry, which generates high-density displacement maps (>3 million points on a 300 mm wafer) such that the stresses induced die-by-die and process-by-process can be tracked in detail. The results indicate the relationship between displacement and overlay shows the ability to forecast overlay values before the lithographic process. Details of the correlation including overlay/displacement range, and lot-to-lot displacement variability are considered.

  9. Formation of x-ray vortex dipoles using a single diffraction pattern and direct phase measurement using interferometry

    SciTech Connect

    Kohmura, Yoshiki; Sawada, Kei; Taguchi, Munetaka; Ishikawa, Tetsuya; Ohigashi, Takuji; Suzuki, Yoshio

    2009-03-09

    We have devised a method for generating x-ray vortices by using a diffraction pattern from a simple aperture with illumination wave fronts with spherical curvatures. The interferometry visualized the x-ray vortex dipoles by the direct phase measurement. Our interference technique enabled us to sensitively detect and quantitatively measure various phase dislocations on the x-ray wave fronts, providing useful methodologies for beam diagnostics and materials science.

  10. Application of Laser Speckle Pattern Interferometry for Precise Measurements of Displacement Distribution in Porous Ceramics

    NASA Astrophysics Data System (ADS)

    Miyata, Hiroshi; Murakami, Akira; Kato, Motoki

    This paper deals with experiments for detecting two-dimensional microscopic deformations by laser speckle pattern interferometry system. The optical setup uses a laser diode for the source together with a lens to expand the laser beam, and an inspection area can be chosen with the optical setup between 5×7.5 mm2 (microscopic range) up to 200×300 mm2 (macroscopic range). The measurements by the macroscopic and microscopic ranges are performed without marking to get overall and detailed deformations of porous ceramic materials respectively. In the macroscopic measurement, it was shown that pore of the ceramics is recognized as a kind of the marker in generating interference fringe. On the other hand, displacement behavior related to the microscopic structure of material can be observed when spatial decomposition of measuring distance is smaller than the pore size is achieved by limiting the inspection area to micro region. In this condition, displacement data with continuous distribution has not been obtained, because displacement measured at pore inside and that at material surface are detected in the one under way without distinguishing at all in the measurement for this microscopic region. However, through the measurement of displacement behavior in crack tip vicinity, it was confirmed that measured displacement distribution agrees with the analytic solution if the data is detected in the position where pore and surface concavity are avoided along the crack edge. By arranging measured data based on above-mentioned processing, valuable information such as strain distributions between adjacent pore was obtained from the measurement for microscopic region.

  11. Radio frequency controlled synthetic wavelength sweep for absolute distance measurement by optical interferometry

    SciTech Connect

    Le Floch, Sebastien; Salvade, Yves; Mitouassiwou, Rostand; Favre, Patrick

    2008-06-01

    We present a new technique applied to the variable optical synthetic wavelength generation in optical interferometry. It consists of a chain of optical injection locking among three lasers: first a distributed-feedback laser is used as a master to injection lock an intensity-modulated laser that is directly modulated around 15 GHz by a radio frequency generator on a sideband. A second distributed-feedback laser is injection locked on another sideband of the intensity-modulated laser. The variable synthetic wavelength for absolute distance measurement is simply generated by sweeping the radio frequency over a range of several hundred megahertz, which corresponds to the locking range of the two slave lasers. In this condition, the uncertainty of the variable synthetic wavelength is equivalent to the radio frequency uncertainty. This latter has a relative accuracy of 10{sup -7} or better, resulting in a resolution of {+-}25 {mu}m for distances exceeding tens of meters. The radio frequency generator produces a linear frequency sweep of 1 ms duration (i.e., exactly equal to one absolute distance measurement acquisition time), with frequency steps of about 1 MHz. Finally, results of absolute distance measurements for ranges up to 10 m are presented.

  12. Radio frequency controlled synthetic wavelength sweep for absolute distance measurement by optical interferometry.

    PubMed

    Le Floch, Sébastien; Salvadé, Yves; Mitouassiwou, Rostand; Favre, Patrick

    2008-06-01

    We present a new technique applied to the variable optical synthetic wavelength generation in optical interferometry. It consists of a chain of optical injection locking among three lasers: first a distributed-feedback laser is used as a master to injection lock an intensity-modulated laser that is directly modulated around 15 GHz by a radio frequency generator on a sideband. A second distributed-feedback laser is injection locked on another sideband of the intensity-modulated laser. The variable synthetic wavelength for absolute distance measurement is simply generated by sweeping the radio frequency over a range of several hundred megahertz, which corresponds to the locking range of the two slave lasers. In this condition, the uncertainty of the variable synthetic wavelength is equivalent to the radio frequency uncertainty. This latter has a relative accuracy of 10(-7) or better, resulting in a resolution of +/-25 microm for distances exceeding tens of meters. The radio frequency generator produces a linear frequency sweep of 1 ms duration (i.e., exactly equal to one absolute distance measurement acquisition time), with frequency steps of about 1 MHz. Finally, results of absolute distance measurements for ranges up to 10 m are presented. PMID:18516123

  13. Study of the Earth's interior using measurements of sound velocities in minerals by ultrasonic interferometry

    SciTech Connect

    Li, Baosheng; Liebermann, Robert C.

    2014-07-29

    This paper reviews the progress of the technology of ultrasonic interferometry from the early 1950s to the present day. During this period of more than 60 years, sound wave velocity measurements have been increased from at pressures less than 1 GPa and temperatures less than 800 K to conditions above 25 GPa and temperatures of 1800 K. This is complimentary to other direct methods to measure sound velocities (such as Brillouin and impulsive stimulated scattering) as well as indirect methods (e.g., resonance ultrasound spectroscopy, static or shock compression, inelastic X-ray scattering). Newly-developed pressure calibration methods and data analysis procedures using a finite strain approach are described and applied to data for the major mantle minerals. The implications for the composition of the Earth’s mantle are discussed. The state-of-the-art ultrasonic experiments performed in conjunction with synchrotron X-radiation can provide simultaneous measurements of the elastic bulk and shear moduli and their pressure and temperature derivatives with direct determination of pressure. The current status and outlook/challenges for future experiments are summarized.

  14. Simple digital phase-measuring algorithm for low-noise heterodyne interferometry

    NASA Astrophysics Data System (ADS)

    Kokuyama, Wataru; Nozato, Hideaki; Ohta, Akihiro; Hattori, Koichiro

    2016-08-01

    We present a digital algorithm for measuring the phase of a sinusoidal signal that combines the modified digital fringe-counting method with two-sample zero crossing to enable sequential signal processing. This technique can be applied to a phase meter for measuring dynamic phase differences between two sinusoidal signals with high resolution, particularly for heterodyne interferometry. The floor noise obtained from a demonstration with an electrical apparatus is 5× {{10}-8} \\text{rad}\\text{/}{{\\sqrt{\\text{Hz}}}{}} at frequencies above approximately 0.1 Hz for 80 kHz signal frequency. In addition, by applying this method to a commercial heterodyne interferometer with a modulation frequency of 80 MHz, the floor-noise level is confirmed to be 7× {{10}-14}\\text{m}\\text{/}{{\\sqrt{\\text{Hz}}}{}} from 4 kHz to 1 MHz. We also confirm the validity of the algorithm by comparing its results with those from a standard homodyne interferometer for measuring shock-motion peak acceleration greater than 5000 \\text{m} {{\\text{s}}-2} and a 10 mm stroke.

  15. Measurement of a fiber-end surface profile by use of phase-shifting laser interferometry

    NASA Astrophysics Data System (ADS)

    Wang, Shihua; Quan, Chenggen; Tay, Cho Jui; Reading, Ivan; Fang, Zhongping

    2004-01-01

    We describe a laser interferometric system in which two objectives are used to measure surface profile on a connectorized fiber-end surface. By the use of the proposed illumination design a He-Ne laser as a point light source is transformed to an extended light source, which is beneficial to localize interference fringe pattern near the test surface. To obtain an optimal contrast of the interference fringe pattern, the flat mirror with an adjustable reflection ratio is used to suit different test surfaces. A piezoelectric transducer attached on the reference mirror can move precisely along the optical axis of the objective and permits implementation of four-step phase-shifting interferometry without changing the relative position between the CCD sensor and the test surface. Therefore, an absolutely constant optical magnification can be accurately kept to capture the interference fringe patterns resulting from a combination of light reflected from both the reference flat mirror and the test surface. The experimental result shows that surface profile on a fiber-end with surface features such as a small fiber diameter of 125 μm and a low reflection ratio of less than 4% are measurable. Measurements on a standard calibration ball show that the accuracy of the proposed setup is comparable with that of existing white-light interferometers and stylus profilometers.

  16. Precision measurement of refractive index of air based on laser synthetic wavelength interferometry with Edlén equation estimation.

    PubMed

    Yan, Liping; Chen, Benyong; Zhang, Enzheng; Zhang, Shihua; Yang, Ye

    2015-08-01

    A novel method for the precision measurement of refractive index of air (n(air)) based on the combining of the laser synthetic wavelength interferometry with the Edlén equation estimation is proposed. First, a n(air_e) is calculated from the modified Edlén equation according to environmental parameters measured by low precision sensors with an uncertainty of 10(-6). Second, a unique integral fringe number N corresponding to n(air) is determined based on the calculated n(air_e). Then, a fractional fringe ε corresponding to n(air) with high accuracy can be obtained according to the principle of fringe subdivision of laser synthetic wavelength interferometry. Finally, high accurate measurement of n(air) is achieved according to the determined fringes N and ε. The merit of the proposed method is that it not only solves the problem of the measurement accuracy of n(air) being limited by the accuracies of environmental sensors, but also avoids adopting complicated vacuum pumping to measure the integral fringe N in the method of conventional laser interferometry. To verify the feasibility of the proposed method, comparison experiments with Edlén equations in short time and in long time were performed. Experimental results show that the measurement accuracy of n(air) is better than 2.5 × 10(-8) in short time tests and 6.2 × 10(-8) in long time tests. PMID:26329237

  17. Electronic speckle pattern interferometry technique for the measurement of complex mechanical structures for aero-spatial applications

    NASA Astrophysics Data System (ADS)

    Restrepo, René; Uribe-Patarroyo, Néstor; Garranzo, Daniel; Pintado, José M.; Frovel, Malte; Belenguer, Tomás

    2010-09-01

    Using the electronic speckle pattern interferometry (ESPI) technique in the in-plane arrangement, the coefficient of thermal expansion (CTE) of a composite material that will be used in a passive focusing mechanism of an aerospace mission was measured. This measurement with ESPI was compared with another interferometric method (Differential Interferometer), whose principal characteristic is its high accuracy, but the measurement is only local. As a final step, the results have been used to provide feedback with the finite element analysis (FEA). Before the composite material measurements, a quality assessment of the technique was carried out measuring the CTE of Aluminum 6061-T6. Both techniques were compared with the datasheet delivered by the supplier. A review of the basic concepts was done, especially with regards to ESPI, and the considerations to predict the quality in the fringes formation were explained. Also, a review of the basic concepts for the mechanical calculation in composite materials was done. The CTE of the composite material found was 4.69X10-6 +/- 3X10-6K-1. The most important advantage between ESPI and differential interferometry is that ESPI provides more information due to its intrinsic extended area, surface deformation reconstruction, in comparison with the strictly local measurement of differential interferometry

  18. Utilization of coincidence criteria in absolute length measurements by optical interferometry in vacuum and air

    NASA Astrophysics Data System (ADS)

    Schödel, R.

    2015-08-01

    Traceability of length measurements to the international system of units (SI) can be realized by using optical interferometry making use of well-known frequencies of monochromatic light sources mentioned in the Mise en Pratique for the realization of the metre. At some national metrology institutes, such as Physikalisch-Technische Bundesanstalt (PTB) in Germany, the absolute length of prismatic bodies (e.g. gauge blocks) is realized by so-called gauge-block interference comparators. At PTB, a number of such imaging phase-stepping interference comparators exist, including specialized vacuum interference comparators, each equipped with three highly stabilized laser light sources. The length of a material measure is expressed as a multiple of each wavelength. The large number of integer interference orders can be extracted by the method of exact fractions in which the coincidence of the lengths resulting from the different wavelengths is utilized as a criterion. The unambiguous extraction of the integer interference orders is an essential prerequisite for correct length measurements. This paper critically discusses coincidence criteria and their validity for three modes of absolute length measurements: 1) measurements under vacuum in which the wavelengths can be identified with the vacuum wavelengths, 2) measurements under air in which the air refractive index is obtained from environmental parameters using an empirical equation, and 3) measurements under air in which the air refractive index is obtained interferometrically by utilizing a vacuum cell placed along the measurement pathway. For case 3), which corresponds to PTB’s Kösters-Comparator for long gauge blocks, the unambiguous determination of integer interference orders related to the air refractive index could be improved by about a factor of ten when an ‘overall dispersion value,’ suggested in this paper, is used as coincidence criterion.

  19. The Development and Hover Test Application of a Projection Moire Interferometry Blade Displacement Measurement System

    NASA Technical Reports Server (NTRS)

    Sekula, Martin K.

    2012-01-01

    Projection moir interferometry (PMI) was employed to measure blade deflections during a hover test of a generic model-scale rotor in the NASA Langley 14x22 subsonic wind tunnel s hover facility. PMI was one of several optical measurement techniques tasked to acquire deflection and flow visualization data for a rotor at several distinct heights above a ground plane. Two of the main objectives of this test were to demonstrate that multiple optical measurement techniques can be used simultaneously to acquire data and to identify and address deficiencies in the techniques. Several PMI-specific technical challenges needed to be addressed during the test and in post-processing of the data. These challenges included developing an efficient and accurate calibration method for an extremely large (65 inch) height range; automating the analysis of the large amount of data acquired during the test; and developing a method to determinate the absolute displacement of rotor blades without a required anchor point measurement. The results indicate that the use of a single-camera/single-projector approach for the large height range reduced the accuracy of the PMI system compared to PMI systems designed for smaller height ranges. The lack of the anchor point measurement (due to a technical issue with one of the other measurement techniques) limited the ability of the PMI system to correctly measure blade displacements to only one of the three rotor heights tested. The new calibration technique reduced the data required by 80 percent while new post-processing algorithms successfully automated the process of locating rotor blades in images, determining the blade quarter chord location, and calculating the blade root and blade tip heights above the ground plane.

  20. Status of a UAVSAR designed for repeat pass interferometry for deformation measurements

    NASA Technical Reports Server (NTRS)

    Hensley, Scott; Wheeler, Kevin; Sadowy, Greg; Miller, Tim; Shaffer, Scott; Muellerschoen, Ron; Jones, Cathleen; Zebker, Howard; Madsen, Soren; Paul, Rose

    2005-01-01

    NASA's Jet Propulsion Laboratory is currently implementing a reconfigurable polarimetric L-band synthetic aperture radar (SAR), specifically designed to acquire airborne repeat track interferometric (RTI) SAR data, also known as differential interferometric measurements. Differential interferometry can provide key deformation measurements, important for the scientific studies of Earthquakes and volcanoes. Using precision real-time GPS and a sensor controlled flight management system, the system will be able to fly predefined paths with great precision. The expected performance of the flight control system will constrain the flight path to be within a 10 m diameter tube about the desired flight track. The radar wilI be designed to operate on a UAV (Unpiloted Aria1 Vehicle) but will initially be demonstrated on a minimally piloted vehicle (MPV), such as the Proteus buitt by Scaled Composites or on a NASA Gulfstream III. The radar design is a fully polarimetric with an 80 MHz bandwidth (2 m range resolution) and 16 km range swath. The antenna is an electronically steered along track to assure that the actual antenna pointing can be controlled independent of the wind direction and speed. Other features supported by the antenna include an elevation monopulse option and a pulse-to-pulse resteering capability that will enable some novel modes of operation. The system will nominally operate at 45,000 ft (13800 m). The program began out as an Instrument Incubator Project (IIP) funded by NASA Earth Science and Technology Office (ESTO).

  1. Time course and topographic distribution of ocular fundus pulsation measured by low-coherence tissue interferometry.

    PubMed

    Dragostinoff, Nikolaus; Werkmeister, René M; Klaizer, József; Gröschl, Martin; Schmetterer, Leopold

    2013-12-01

    Low-coherence tissue interferometry is a technique for the depth-resolved measurement of ocular fundus pulsations. Whereas fundus pulsation amplitudes at preselected axial positions can readily be assessed by this method, coupling of the interferometer with a pulse oximeter additionally allows for the reconstruction of the time course of ocular fundus pulsation with respect to the cardiac cycle of the subject. For this purpose, the interferogram resulting from the superposition of waves reflected at the cornea and the ocular fundus is recorded synchronously with the plethysmogram. A new method for evaluating the time course of synthetic interferograms in combination with plethysmograms based on averaging several pulse periods has been developed. This technique allows for the analysis of amplitudes, time courses, and phase differences of fundus pulsations at preselected axial and transversal positions and for creating fundus pulsation movies. Measurements are performed in three healthy emmetropic subjects at angles from 0 deg to 18 deg to the axis of vision. Considerably different time courses, amplitudes, and phases with respect to the cardiac cycle are found at different angles. Data on ocular fundus pulsation obtained with this technique can--among other applications--be used to verify and to improve biomechanical models of the eye. PMID:24091698

  2. Real-time holographic interferometry to measure displacement of the facial bone

    NASA Astrophysics Data System (ADS)

    Matsumoto, Toshiro; Tamamura, Kentaro; Tsuchida, Masahisa; Hashimoto, Seiichi; Yabuuchi, Hisashi; Uemura, Kazuyoshi; Sugimura, Masahito

    1998-01-01

    The deformation of the facial bone made up of many complex- formed bones was measured and the role of suture considered with the mechanical response. The displacement of human dried facial bone was measured and considered under static loads by real time holographic interferometry. Materials were dried human skulls. Various loads were applied to the zygomatic, maxillary and the other facial bones by means of a loading apparatus. As the experimental result obtained from the load to the neighborhood of the temporo-zygomatic suture on the temporal bone, density of interference fringes increased on the temporal bone more than on the zygomatic and other facial bones and parallel interference fringes were observed on the temporal bone. The buffer effect on the temporo-zygomatic suture to the load was greater than the sutures of other facial bones. When the amount of load was increased on the same bone, it was expected that the zygomatic arch was broken independently as the type II of the fracture patterns by Knight and NOrth. When the neighborhood of the median suture on the maxillary bone was loaded, fine interference fringes were observed horizontally on the maxillary and zygomatic bones, while coarse interference fringes occurred on the frontal bone and the bilateral fracture pattern by LeFort was expected.

  3. Fast and economic signal processing technique of laser diode self-mixing interferometry for nanoparticle size measurement

    NASA Astrophysics Data System (ADS)

    Wang, Huarui; Shen, Jianqi

    2014-05-01

    The size of nanoparticles is measured by laser diode self-mixing interferometry, which employs a sensitive, compact, and simple optical setup. However, the signal processing of the interferometry is slow or expensive. In this article, a fast and economic signal processing technique is introduced, in which the self-mixing AC signal is transformed into DC signals with an analog circuit consisting of 16 channels. These DC signals are obtained as a spectrum from which the size of nanoparticles can be retrieved. The technique is examined by measuring the standard nanoparticles. Further experiments are performed to compare the skimmed milk and whole milk, and also the fresh skimmed milk and rotten skimmed milk.

  4. Evaluation of the wave measurement in a stormy sea by the Along-Track interferometry SAR

    NASA Astrophysics Data System (ADS)

    Kojima, S.

    2015-12-01

    NICT developed the along-track interferometry SAR (AT-InSAR) system to detect the running cars and ships and measure sea surface velocity in 2011. The preliminary experiments for the running truck and ship were performed and it confirmed that the system performance was satisfactory to its specifications. In addition, a method to estimate the wave height from the sea surface velocity measured by the AT-InSAR was developed. The preliminary wave height observation was performed in a calm sea, and it was confirmed that the wave height could be estimated from the measured sea surface velocity. The purpose of this study is to check the capability of the ocean waves observation in a stormy sea by the AT-InSAR. Therefore, the ocean wave observation was performed under the low atmospheric pressure. The observation area is the sea surface at 10 km off the coast of Kushiro, south-east to Hokaido, JAPAN on the 4th of March 2015. The wind speed was 8〜10m/s during the observation, and the significant wave height and period were 1.5m and 6.0s. The observation was performed in 2 directions and the accuracy of the estimation results were checked. The significant wave height and period measured by the AT-InSAR agreed with it measured by the wave gage located close to this observation area. In addition, it was confirmed that there were no irregular wave heights in the distribution of the estimated wave height. As a result, it became clear that the AT-InSAR could observe the wave height in a stormy sea.

  5. Spectrally resolved white light interferometry to measure material dispersion over a wide spectral band in a single acquisition.

    PubMed

    Arosa, Yago; Lago, Elena López; Varela, Luis Miguel; de la Fuente, Raúl

    2016-07-25

    In this paper we apply spectrally resolved white light interferometry to measure refractive and group index over a wide spectral band from 400 to 1000 nm. The output of a Michelson interferometer is spectrally decomposed by a homemade prism spectrometer with a high resolution camera. The group index is determined directly from the phase extracted from the spectral interferogram while the refractive index is estimated once its value at a given wavelength is known. PMID:27464179

  6. Measurement of the Optical Coherence of a Femtosecond Pulsed Laser by Shearing Interferometry with a Double-Frequency Grating

    NASA Astrophysics Data System (ADS)

    Ming, Hai; Qian, Jiang-yuan; Xie, Jian-ping; A, B. Fedotov; X, Xiao; M, M. T. Loy

    1998-01-01

    Shearing interferometry of an ion-etched holographic double-frequency grating is used to measure the optical coherence of femtosecond pulsed lasers. The experimental results show that the optical coherence of the femtosecond light beam is not only related to the spectral width and size of the light source but is also related to the pulse duration and mode-locked laser state. The results of theoretical analysis and numerical calculation are also given. Application of this research is also discussed.

  7. Measurement of displacement using phase shifted wedge plate lateral shearing interferometry

    NASA Astrophysics Data System (ADS)

    Disawal, Reena; Prakash, Shashi

    2016-03-01

    In present communication, a simple technique for measurement of displacement using phase shifted wedge plate lateral shearing interferometry is described. The light beam from laser is expanded and illuminates a wedge plate of relatively large angle. Light transmitted through the wedge plate is converged onto a reflecting specimen using a focusing lens. Back-reflected wavefront from the specimen is incident on the wedge plate. Because of the tilt and shear of the wavefront reflected from the wedge plate, typical straight line fringes appear. These fringes are superimposed onto a sinusoidal grating forming a moiré pattern. The orientation of the moiré fringes is a function of specimen displacement. Four step phase shifting test procedure has been incorporated by translating the grating in phase steps of π/2. Necessary mathematical formulation to establish correlation between the 'difference phase' and the displacement of the specimen surface is undertaken. The technique is automatic and provides resolution and expanded uncertainty of 1 μm and 0.246 μm, respectively. Detailed uncertainty analysis is also reported.

  8. Detection of atmospheric pressure loading using very long baseline interferometry measurements

    NASA Technical Reports Server (NTRS)

    Vandam, T. M.; Herring, T. A.

    1994-01-01

    Loading of the Earth by the temporal redistribution of global atmospheric mass is likely to displace the positions of geodetic monuments by tens of millimeters both vertically and horizontally. Estimates of these displacements are determined by convolving National Meteorological Center (NMC) global values of atmospheric surface pressure with Farrell's elastic Green's functions. An analysis of the distances between radio telescopes determined by very long baseline interferometry (VLBI) between 1984 and 1992 reveals that in many of the cases studied there is a significant contribution to baseline length change due to atmospheric pressure loading. Our analysis covers intersite distances of between 1000 and 10,000 km and is restricted to those baselines measured more than 100 times. Accounting for the load effects (after first removing a best fit slope) reduces the weighted root-mean-square (WRMS) scatter of the baseline length residuals on 11 of the 22 baselines investigated. The slight degradation observed in the WRMS scatter on the remaining baselines is largely consistent with the expected statistical fluctuations when a small correction is applied to a data set having a much larger random noise. The results from all baselines are consistent with approximately 60% of the computed pressure contribution being present in the VLBI length determinations. Site dependent coefficients determined by fitting local pressure to the theoretical radial displacement are found to reproduce the deformation caused by the regional pressure to within 25% for most inland sites. The coefficients are less reliable at near coastal and island stations.

  9. Deformation measurements of composite multi-span beam shear specimens by Moire interferometry

    NASA Technical Reports Server (NTRS)

    Post, D.; Czarnek, R.; Joh, D.; Wood, J.

    1984-01-01

    Experimental analyses were performed for determination of in plane deformations and shear strains in unidirectional and quasi-isotropic graphite-epoxy beams. Forty-eight ply beams were subjected to 5 point and 3 point flexure. Whole field measurements were recorded at load levels from about 20% to more than 90% of failure loads. Contour maps of U and W displacement fields were obtained by moire interferometry, using reference gratings of 2400 lines/mm. Clearly defined fringes with fringe orders exceeding 1000 were obtained. Whole field contour maps of shear strains were obtained by a method developed for these tests. Various anomalous effects were detected in the displacement fields. Their analysis indicated excess shear strains in resin rich zones in regions of shear tractions; free edge shear strains in quasi-isotropic specimens in regions of normal stresses; and shear stresses associated with cyclic shear compliances of quasi-isotropic plies in regions of shear tractions. Their contributions could occur independently or in superposition. Qualitative analyses addressed questions of relaxation; influence of contact stress distribution; specimen failure; effect of specimen overhang; nonlinearity; and qualities of 5 and 3 point flexure tests.

  10. Deformation of the Augustine Volcano, Alaska, 1992-2005, measured by ERS and ENVISAT SAR interferometry

    USGS Publications Warehouse

    Lee, Chang-Wook; Lu, Zhong; Kwoun, Oh-Ig; Won, Joong-Sun

    2008-01-01

    The Augustine Volcano is a conical-shaped, active stratovolcano located on an island of the same name in Cook Inlet, about 290 km southwest of Anchorage, Alaska. Augustine has experienced seven significant explosive eruptions - in 1812, 1883, 1908, 1935, 1963, 1976, 1986, and in January 2006. To measure the ground surface deformation of the Augustine Volcano before the 2006 eruption, we applied satellite radar interferometry using Synthetic Aperture Radar (SAR) images from three descending and three ascending satellite tracks acquired by European Remote Sensing Satellite (ERS) 1 and 2 and the Environment Satellite (ENVISAT). Multiple interferograms were stacked to reduce artifacts caused by atmospheric conditions, and we used a singular value decomposition method to retrieve the temporal deformation history from several points on the island. Interferograms during 1992 and 2005 show a subsidence of about 1-3 cm/year, caused by the contraction of pyroclastic flow deposits from the 1986 eruption. Subsidence has decreased exponentially with time. Multiple interferograms between 1992 and 2005 show no significant inflation around the volcano before the 2006 eruption. The lack of a pre-eruption deformation signal suggests that the deformation signal from 1992 to August 2005 must have been very small and may have been obscured by atmospheric delay artifacts. 

  11. Single-shot depth-resolved displacement field measurement using phase-contrast polychromatic speckle interferometry

    NASA Astrophysics Data System (ADS)

    Ruiz, Pablo D.; de la Torre-Ibarra, Manuel; Huntley, Jonathan M.

    2006-09-01

    We describe a system for measuring sub-surface displacement fields within a scattering medium using a broadband super-luminescent light emitting diode (SLED) source and spectral imaging. The use of phase information in the backscattered speckle pattern offers displacement sensitivity in the range of a few tens of nm, some two to three orders of magnitude better than the depth resolution of state-of-the-art Optical Coherence Tomography systems. The system is based on low cost components and has no moving parts. It provides displacement maps within a 2-D slice extending into the sample, and the fact that all the data for a given deformation state are acquired in a single shot is a highly attractive feature for in-vivo investigations in the biological sciences. The theoretical basis for the system is presented along with experimental results from a simple well-controlled geometry consisting of independently-tilting glass sheets. Results are validated using standard two-beam interferometry. Scattering samples were also studied and we show a wrapped phase map through the thickness of a pig ex-vivo cornea. The phase change was due to viscoelastic creep in the cornea after a change in the intraocular pressure.

  12. Status of a UAV SAR Designed for Repeat Pass Interferometry for Deformation Measurements

    NASA Technical Reports Server (NTRS)

    Hensley, Scott; Wheeler, Kevin; Hoffman, Jim; Miller, Tim; Lou, Yunling; Muellerschoen, Ron; Zebker, Howard; Madsen, Soren; Rosen, Paul

    2004-01-01

    Under the NASA ESTO sponsored Instrument Incubator Program we have designed a lightweight, reconfigurable polarimetric L-band SAR designed for repeat pass deformation measurements of rapidly deforming surfaces of geophysical interest such as volcanoes or earthquakes. This radar will be installed on an unmanned airborne vehicle (UAV) or a lightweight, high-altitude, and long endurance platform such as the Proteus. After a study of suitable available platforms we selected the Proteus for initial development and testing of the system. We want to control the repeat track capability of the aircraft to be within a 10 m tube to support the repeat deformation capability. We conducted tests with the Proteus using real-time GPS with sub-meter accuracy to see if pilots could fly the aircraft within the desired tube. Our results show that pilots are unable to fly the aircraft with the desired accuracy and therefore an augmented autopilot will be required to meet these objectives. Based on the Proteus flying altitude of 13.7 km (45,000 ft), we are designing a fully polarimetric L-band radar with 80 MHz bandwidth and 16 km range swath. This radar will have an active electronic beam steering antenna to achieve Doppler centroid stability that is necessary for repeat-pass interferometry (RPI). This paper will present are design criteria, current design and expected science applications.

  13. Measurement of displacement on facial bone by real-time holographic interferometry

    NASA Astrophysics Data System (ADS)

    Matsumoto, Toshiro; Taga, Masao; Tsuchida, Masahisa; Yoshioka, Minoru; Uemura, Kazuyoshi; Sugimura, Masahito

    1996-01-01

    The displacement of human dried facial bone was measured and considered under static loads by real time holographic interferometry. Materials were dried human skulls. Various loads were applied to the zygomatic, maxillary and other facial bones by means of a loading apparatus. As the experimental result obtained from the load to the neighborhood of the fronto-malar suture on the zygomatic bone, density of interference fringes increased on the zygomatic bone more than on the other facial bones and parallel interference fringes were observed on the zygomatic bone. Densities of orbital maxillary and zygomatic bones were greater, when the load was applied to the center of infraorbital margin than when it was applied to the other facial bones. When the neighborhood of the front-malar suture on the frontal bone was loaded, coarse interference fringes occurred on the zygomatic, maxillary and orbital bones, while fine interference fringes appeared on the frontal bone. When the maxillary bone near infraorbital margin was loaded, concentric circular fringes were observed. The result shows that the displacement depends on the loading point. When the load applied to the zygomatic bone, parallel fringes appeared on the bone. This means that the bone deformed almost as a body.

  14. Geodetic measurement of deformation in the Loma Prieta, California earthquake with Very Long Baseline Interferometry (VLBI)

    SciTech Connect

    Clark, T.A.; Ma, C.; Sauber, J.M.; Ryan, J.W. ); Gordon, D.; Caprette, D.S. ); Shaffer, D.B.; Vandenberg, N.R. )

    1990-07-01

    Following the Loma Prieta earthquake, two mobile Very Long Baseline Interferometry (VLBI) systems operated by the NASA Crustal Dynamics Project and the NOAA National Geodetic Survey were deployed at three previously established VLBI sites in the earthquake area: Fort Ord (near Monterey), the Presidio (in San Francisco) and Point Reyes. From repeated VLBI occupations of these sites since 1983, the pre-earthquake rates of deformation have been determined with respect to a North American reference frame with 1{sigma} formal standard errors of {approximately}1 mm/yr. The VLBI measurements immediately following the earthquake showed that the Fort Ord site was displaced 49 {plus minus} 4 mm at an azimuth of 11 {plus minus} 4{degree} and that the Presidio site was displaced 12 {plus minus} 5 mm at an azimuth of 148 {plus minus} 13{degree}. No anomalous change was detected at Point Reyes with 1{sigma} uncertainty of 4 mm. The estimated displacements at Fort Ord and the Presidio are consistent with the static displacements predicted on the basis of a coseismic slip model in which slip on the southern segment is shallower than slip on the more northern segment is shallower than slip on the more northern segment of the fault rupture. The authors also give the Cartesian positions at epoch 1990.0 of a set of VLBI fiducial stations and the three mobile sites in the vicinity of the earthquake.

  15. Systematic approach based on holographic interferometry measurements to characterize the flame structure of partially premixed flames.

    PubMed

    Xiao, X; Puri, I K

    2001-02-20

    Partially premixed flames (PPF's) represent a class of hybrid flames that contain multiple reaction zones. A detailed understanding of the temperature distribution in PPF's is important from both practical and scientific considerations. Path-integrated or line-of-sight measurement techniques, such as holographic interferometry (HI), that are based on the change in the optical phase of a light beam can be used to reconstruct the refractive index n in flames and thereafter to infer the temperature distribution. Therefore to describe the flame structure in the context of these measurements requires that a systematic approach be developed that relates the density, the temperature, and the composition to the refractive index. We demonstrate that a conserved scalar xi that transforms the flame structure from a spatial to a generic distribution can be inferred from the refractive-index distribution. Thereafter measurements of the density, the temperature, and the composition in two-dimensional PPF's become feasible. We report the first application, to our knowledge, of this method to HI. Specifically, we used HI to measure the refractive-index distributions in methane-air PPF's. One PPF is a double flame that has two reaction zones, and the other is a triple flame that contains three reaction zones. We have applied the procedure to infer the distribution of the modified mixture fraction and thereafter the local temperature and the local mass fractions. We find the local temperature differences, DT(x, y) = |T[n(x, y)] - T?[xi(x, y)]|, to be relatively small. We conclude that it is possible to use HI to infer the mixture-fraction distribution and thereafter the flame structures by the application of state relations in the case of PPF's. PMID:18357052

  16. 2D image of local density and magnetic fluctuations from line-integrated interferometry-polarimetry measurements

    SciTech Connect

    Lin, L. Ding, W. X.; Brower, D. L.

    2014-11-15

    Combined polarimetry-interferometry capability permits simultaneous measurement of line-integrated density and Faraday effect with fast time response (∼1 μs) and high sensitivity. Faraday effect fluctuations with phase shift of order 0.05° associated with global tearing modes are resolved with an uncertainty ∼0.01°. For physics investigations, local density fluctuations are obtained by inverting the line-integrated interferometry data. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of the polarimetry data. Reconstructed 2D images of density and magnetic field fluctuations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved.

  17. Measurement of a density profile of a hot-electron plasma in RT-1 with three-chord interferometry

    NASA Astrophysics Data System (ADS)

    Saitoh, H.; Yano, Y.; Yoshida, Z.; Nishiura, M.; Morikawa, J.; Kawazura, Y.; Nogami, T.; Yamasaki, M.

    2015-02-01

    The electron density profile of a plasma in a magnetospheric dipole field configuration was measured with a multi-chord interferometry including a relativistic correction. In order to improve the accuracy of density reconstruction, a 75 GHz interferometer was installed at a vertical chord of the Ring Trap 1 (RT-1) device in addition to previously installed ones at tangential and another vertical chords. The density profile was calculated by using the data of three-chord interferometry including relativistic effects for a plasma consisting of hot and cold electrons generated by electron cyclotron resonance heating (ECH). The results clearly showed the effects of density peaking and magnetic mirror trapping in a strongly inhomogeneous dipole magnetic field.

  18. Measurement of a density profile of a hot-electron plasma in RT-1 with three-chord interferometry

    SciTech Connect

    Saitoh, H.; Yano, Y.; Yoshida, Z.; Nishiura, M.; Morikawa, J.; Kawazura, Y.; Nogami, T.; Yamasaki, M.

    2015-02-15

    The electron density profile of a plasma in a magnetospheric dipole field configuration was measured with a multi-chord interferometry including a relativistic correction. In order to improve the accuracy of density reconstruction, a 75 GHz interferometer was installed at a vertical chord of the Ring Trap 1 (RT-1) device in addition to previously installed ones at tangential and another vertical chords. The density profile was calculated by using the data of three-chord interferometry including relativistic effects for a plasma consisting of hot and cold electrons generated by electron cyclotron resonance heating (ECH). The results clearly showed the effects of density peaking and magnetic mirror trapping in a strongly inhomogeneous dipole magnetic field.

  19. Cross-Sectional Residual Stresses in Thermal Spray Coatings Measured by Moiré Interferometry and Nanoindentation Technique

    NASA Astrophysics Data System (ADS)

    Zhu, Jianguo; Xie, Huimin; Hu, Zhenxing; Chen, Pengwan; Zhang, Qingming

    2012-09-01

    A plasma-sprayed thermal barrier coating (TBC) was deposited on a stainless steel substrate. The residual stresses were firstly measured by moiré interferometry combined with a cutting relaxation method. The fringe patterns in the cross-section of the specimen clearly demonstrate the deformation caused by the residual stress in thermal spray coatings. However, restricted by the sensitivity of moiré interferometry, there are few fringes in the top coat, and large errors may exist in evaluating the residual stress in the top coat. Then, the nanoindentation technique was used to estimate the residual stresses across the coating thickness. The stress/depth profile shows that the process-induced stresses after thermal spray are compressive in the top coat and a tendency to a more compressive state toward the interface. In addition, the stress gradient in the substrate is nonlinear, and tensile and compressive stresses appear simultaneously for self-equilibrium in the cross-section.

  20. A Electronic Speckle Pattern Interferometry for Surface Strain Measurements of a Three-Dimensional Object

    NASA Astrophysics Data System (ADS)

    Chitsaz, Bijan

    The objective of this research was to develop a method for calculating the strain field in three-dimensional objects using electronic speckle pattern interferometry. Two interferometers were utilized for three-dimensional displacement field measurements, and derivation of their optical phase difference relationships are detailed. It was shown that the optical phase difference is dependent on the illumination angle(s) and the wavelength of the illuminating laser. The overall optical system arrangement designed for the three -dimensional displacement field measurements is presented. The Cartesian coordinate displacement components, u, v, or w, at any point on the viewing surface of an object were interpolated by fitting curves through displacement values represented by the fringe centers. The gradients of the displacement curves along the axial and tangential directions were used for strain measurements. A circular cross-section cantilever beam subjected to an eccentric compressive load with known displacement characteristics was used for calibration purposes. The strain fields at a point on the surface of the beam subjected to three different loads were calculated. The reproducibility of the ESPI system was examined by conducting three identical experiments on the cylinder. Each set included assembling and disassembling of the model, disturbing and readjusting of the optical components, and repetitive loading and unloading of the model. The percent difference and standard deviation based on strain values which were obtained from these experiments were calculated and tabulated and compared to theoretical calculations based on beam theory. The system is reported to be highly reproducible with a maximum percent error of 8.2% associated with epsilon_{ theta z}.. The newly developed system was also applied to testing of a human femur with and without femoral prosthesis implantation. The effects of two types of hip implants (press-fit and cemented) on the surface strain

  1. Snowpack displacement measured by terrestrial radar interferometry as precursor for wet snow avalanches

    NASA Astrophysics Data System (ADS)

    Caduff, Rafael; Wiesmann, Andreas; Bühler, Yves

    2016-04-01

    Wet snow and full depth gliding avalanches commonly occur on slopes during springtime when air temperatures rise above 0°C for longer time. The increase in the liquid water content changes the mechanical properties of the snow pack. Until now, forecasts of wet snow avalanches are mainly done using weather data such as air and snow temperatures and incoming solar radiation. Even tough some wet snow avalanche events are indicated before the release by the formation of visible signs such as extension cracks or compressional bulges in the snow pack, a large number of wet snow avalanches are released without any previously visible signs. Continuous monitoring of critical slopes by terrestrial radar interferometry improves the scale of reception of differential movement into the range of millimetres per hour. Therefore, from a terrestrial and remote observation location, information on the mechanical state of the snow pack can be gathered on a slope wide scale. Recent campaigns in the Swiss Alps showed the potential of snow deformation measurements with a portable, interferometric real aperture radar operating at 17.2 GHz (1.76 cm wavelength). Common error sources for the radar interferometric measurement of snow pack displacements are decorrelation of the snow pack at different conditions, the influence of atmospheric disturbances on the interferometric phase and transition effects from cold/dry snow to warm/wet snow. Therefore, a critical assessment of those parameters has to be considered in order to reduce phase noise effects and retrieve accurate displacement measurements. The most recent campaign in spring 2015 took place in Davos Dorf/GR, Switzerland and its objective was to observe snow glide activity on the Dorfberg slope. A validation campaign using total station measurements showed good agreement to the radar interferometric line of sight displacement measurements in the range of 0.5 mm/h. The refinement of the method led to the detection of numerous gliding

  2. Continuous in-situ measurement of stress-induced travel time variation with coda interferometry

    NASA Astrophysics Data System (ADS)

    Wang, B.; Zhu, P.; Chen, Y.; Niu, F.; Wang, B.

    2006-12-01

    Use of stress induced seismic velocity changes to understand dynamic processes requires knowledge of the in-situ stress sensitivity of a given rock volume. We have been attempting to estimate this stress sensitivity by continuously measuring travel time between a fixed source and receivers. We have conducted a one-month field experiment near a major active fault in Yunnan province, China. An electric hammer and 7 three- component short-period seismometers were used as source and receivers. The sensor has a natural frequency of 1 Hz and the system has a flat frequency response up to 40 Hz. Data were recorded with a sampling rate of 500 samples per second. Receiver offset ranges from 10.6 m to 1030 m. The source was detonated 6 times a day, starting from 00:30, 01:30, 06:30, 07:30, 22:30 and 23:30, respectively. Each time 30 shots were fired within 12 minutes and the 30 records were stacked to enhance signal to noise ratio (SNR). Partly due to the nature of the source, we were able to record a high quality coda wave with a SNR larger than 100 even after ~ 30 times of the first arrival. Based on the SNR we chose the 2 stations with the smallest offsets (station 1, 10.6 m and station 2, 256.8 m) for analysis. We applied coda interferometry technique to measure subtle changes in the velocity field. At each station we compute the cross correlation between the first seismogram and each subsequent seismogram within a 0.1 s moving time window. The lag time τ(t) is obtained when the maximum cross correlation, C_m(t), is reached. In both stations an linear relationship between the lag time, τ(t), and the elapse time, t was observed. We employed L_1 regression to determine the slope (velocity perturbation δ v/v). Measurement precision in δ v/v is estimated to be less than 10-4. Almost all the previous studies used the first arrival to measure the time perturbations, which could suffer systematic timing errors in the digitizer's base clock and in the triggering time. Using

  3. Spatial phase-shifting interferometry for measurement of aero-optical effects

    SciTech Connect

    Shough, D.M.; Kwon, O.Y.; Leary, D.F. )

    1992-05-01

    Interferometry has long been used to visualize the gas density distribution that results from aerodynamic phenomena. This paper describes an interferometer system that produces quantitative data. The resulting phase maps are high resolution and high accuracy images that are obtained from a single 8 ns laser pulse. A standard Mach-Zehnder interferometer is aligned so that there is approximately Lambda/4 of tilt per pixel. The technique is the spatial equivalent of phase-shifting interferometry. The raw phase maps are calculated and displayed in real time using an image processor. Results are presented from a Mach 3.5 projectile traveling through air. 7 refs.

  4. Renewed uplift at the Yellowstone caldera measured by leveling surveys and satellite radar interferometry

    USGS Publications Warehouse

    Dzurisin, D.; Wicks, C.; Thatcher, W.

    1999-01-01

    A first-order leveling survey across the northeast part of the Yellowstone caldera in September 1998 showed that the central caldera floor near Le Hardy Rapids rose 24 ?? 5 mm relative to the caldera rim at Lake Butte since the previous survey in September 1995. Annual surveys along the same traverse from 1985 to 1995 tracked progressive subsidence near Le Hardy Rapids at an average rate of -19 ?? 1 mm/year. Earlier, less frequent surveys measured net uplift in the same area during 1923-1976 (14 ?? 1 mm/year) and 1976-1984 (22 ?? 1 mm/year). The resumption of uplift following a decade of subsidence was first detected by satellite synthetic aperture radar interferometry, which revealed approximately 15 mm of uplift in the vicinity of Le Hardy Rapids from July 1995 to June 1997. Radar interferograms show that the center of subsidence shifted from the Sour Creek resurgent dome in the northeast part of the caldera during August 1992 to June 1993 to the Mallard Lake resurgent dome in the southwest part during June 1993 to August 1995. Uplift began at the Sour Creek dome during August 1995 to September 1996 and spread to the Mallard Lake dome by June 1997. The rapidity of these changes and the spatial pattern of surface deformation suggest that ground movements are caused at least in part by accumulation and migration of fluids in two sill-like bodies at 5-10 km depth, near the interface between Yellowstone's magmatic and deep hydrothermal systems.

  5. Measurement of Mono- and Polyvalent Carbohydrate-Lectin Binding by Back-Scattering Interferometry

    PubMed Central

    Kussrow, Amanda; Kaltgrad, Eiton; Wolfenden, Mark L.; Cloninger, Mary J.; Finn, M.G.; Bornhop, Darryl J.

    2009-01-01

    Carbohydrate-protein binding is important to many areas of biochemistry. Back-scattering interferometry (BSI) is shown here to be a convenient and sensitive method for obtaining quantitative information about the strengths and selectivities of such interactions. The surfaces of glass microfluidic channels were covalently modified with extravidin, to which biotinylated lectins were subsequently attached by incubation and washing. The binding of unmodified carbohydrates to the resulting avidin-immobilized lectins was monitored by BSI. Dose-response curves, generated within several minutes and highly reproducible in multiple wash/measure cycles, provided adsorption coefficients that showed mannose to bind to concanavalin A with 3.7 times greater affinity than glucose, in line with literature values. Galactose was found to bind selectively and with similar affinity to the lectin BS-1. The avidities of polyvalent sugar-coated virus particles for immobilized conA were far higher than monovalent glycans, with increases of 60–200 fold per glycan when arrayed on the exterior surface of cowpea mosaic virus or bacteriophage Qβ. Sugar-functionalized PAMAM dendrimers showed size-dependent adsorption consistent with the expected density of lectins on the surface. The sensitivity of BSI matches or exceeds that of surface plasmon resonance and quartz crystal microbalance techniques, and differs in its sensitivity to the number of binding events rather than changes in mass. Its operational simplicity, generality, and the near-native conditions under which the target binding proteins are immobilized make it an attractive method for the quantitative characterization of the binding functions of lectins and other proteins. PMID:19462965

  6. Atom Interferometry

    SciTech Connect

    Kasevich, Mark

    2008-05-08

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton's constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gyroscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be used to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  7. Atom Interferometry

    SciTech Connect

    Mark Kasevich

    2008-05-07

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton’s constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  8. Atom Interferometry

    ScienceCinema

    Mark Kasevich

    2010-01-08

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton?s constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  9. Elastic properties of transparent nano-polycrystalline diamond measured by GHz-ultrasonic interferometry and resonant sphere methods

    NASA Astrophysics Data System (ADS)

    Chang, Yun-Yuan; Jacobsen, Steven D.; Kimura, Masaki; Irifune, Tetsuo; Ohno, Ichiro

    2014-03-01

    The sound velocities and elastic moduli of transparent nano-polycrystalline diamond (NPD) have been determined by GHz-ultrasonic interferometry on three different bulk samples, and by resonant spectroscopy on a spherically fabricated NPD sample. We employ a newly-developed optical contact micrometer to measure the thickness of ultrasonic samples to ±0.05 μm with a spatial resolution of ∼50 μm in the same position of the GHz-ultrasonic measurements, resulting in acoustic-wave sound velocity measurements with uncertainties of 0.005-0.02%. The isotropic and adiabatic bulk and shear moduli of NPD measured by GHz-ultrasonic interferometry are KS0 = 442.5 (±0.5) GPa and G0 = 532.4 (±0.5) GPa. By rotating the shear-wave polarization direction, we observe no transverse anisotropy in this NPD. Using resonant sphere spectroscopy, we obtain KS0 = 440.3 (±0.5) GPa and G0 = 532.7 (±0.4) GPa. For comparison, we also measured by GHz-ultrasonic interferometry the elastic constants of a natural single-crystal type-IA diamond with about one-half the experimental uncertainty of previous measurements. The resulting Voigt-Reuss-Hill averaged bulk and shear moduli of natural diamond are KS0 = 441.8 (±0.8) GPa and G0 = 532.6 (±0.5) GPa, demonstrating that the bulk-elastic properties of transparent NPD are equivalent to natural single-crystal diamond as calculated from polycrystalline averaging of its elastic constants.

  10. Measurement of Creep on the Calaveras Fault at Coyote Dam using Terrestrial Radar Interferometry (TRI).

    NASA Astrophysics Data System (ADS)

    Baker, B.; Cassotto, R.; Fahnestock, M. A.; Werner, C. L.; Boettcher, M. S.

    2015-12-01

    The Calaveras fault in central California is part of the San Andreas fault system. Coyote Dam, an earthen dam that straddles the fault ~13km northeast of Gilroy, experiences creep style deformation that ranges from 10 to 15 mm/yr. Uncertainty in the location of the fault, coupled with the historic rate of deformation, affect the dam's safety factor. Assessing the impact of fault creep on the dam's stability is paramount to its safety evaluation, but is difficult to resolve due to limited spatial and temporal sampling of conventional methods. Terrestrial radar interferometry (TRI), like satellite-based observations, produces high spatial resolution maps of ground deformation. Unlike space-based sensors, TRI can be readily deployed and the observation geometry selected to get the maximum line of sight (LOS) signal. TRI also benefits from high temporal sampling which can be used to reduce errors related to atmospheric phase delays and high temporal sampling also facilitates tracking rapidly moving features such as landslides and glaciers. GAMMA Portable Radar Interferometer (GPRI) measurements of Coyote Dam rock faces were made from concrete piers built upstream and downstream of the dam. The GPRI operates at a radar frequency of 17.2 GHz with a spatial resolution at the dam of approximately 0.9 m x 2.0 m. Changes in LOS path length smaller than 0.1mm can be measured. Data were acquired approximately every 2 to 3 weeks over a 7-month period to map the fault trace through the dam faces. Our study exploits the dense record of observations obtained, and the relatively short distance of the radar to the dam to minimize atmospheric affects. We investigate how the deformation evolves in time and the orientation of fault through the dam, including the strike and dip as measured along the dam surface. Our results show rates consistent with GPS data and regional satellite observations, but produce a much more detailed map of the fault on the dam than possible with GPS or

  11. Flow-field measurements on an airfoil with an oscillating trailing-edge using holographic interferometry

    NASA Technical Reports Server (NTRS)

    Bachalo, W. D.

    1984-01-01

    Holographic interferometry data were acquired on an NACA 64A010 airfoil with an oscillating flap. The airfoil was installed in the Ames 11-Foot Transonic Wind Tunnel between splitter plates. Recordings were made at discrete phase angles of the oscillation. The interferometry results provided detailed flow visualization of the shock boundary-layer interaction and the separated flow. Quantitative results were extracted from the interferograms to produce pressure data. These results were compared to the surface pressures obtained with the surface pressure taps. Excellent agreement was found for low angles of incidence. At larger angles of incidence, the flow had greater three-dimensionality, and the results were not in good agreement in some regions of the flow field. Mach contours were traced for representative flow conditions. Wake profiles were also obtained using the assumption of constant pressure across the wake and the Crocco relationship.

  12. Dynamic measurement by digital holographic interferometry based on complex phasor method

    NASA Astrophysics Data System (ADS)

    Tay, C. J.; Quan, C.; Chen, W.

    2009-03-01

    In this paper, complex phasor (CP) method is employed in digital holographic interferometry. Unlike commonly used digital phase subtraction (DPS), the proposed technique processes a CP instead of phase. It is shown that the results obtained by directly filtering the phase produce large errors. It is demonstrated that the phase is not a signal but rather a property of a signal. In addition, the results obtained by the CP method are also compared with those obtained by conventional sine/cosine transformation method.

  13. Application of Shear Plate Interferometry to Jet Diffusion Flame Temperature Measurements

    NASA Technical Reports Server (NTRS)

    VanDerWege, Brad A.; OBrien, Chris J.; Hochgreb, Simone

    1997-01-01

    diagnostics of flames are, however, necessarily limited to detection of radiative emission in the visible range, and offer only qualitative information about the nature of the processes in the flame. In particular, the study sought to understand the structure of the inhibitor-perturbed flames with regard to temperature and species concentration in the outer region of the flame. Whereas thermocouple measurements can be used in ground based studies, their implementation in drop-tower rigs is limited. A possible approach to determine the temperature field around the flame is to use interferometric techniques. The implementation and testing of a shear-plate interferometry technique is described below.

  14. Review and comparison of temporal- and spatial-phase shift speckle pattern interferometry for 3D deformation measurement

    NASA Astrophysics Data System (ADS)

    Xie, Xin; Yang, Lianxiang; Chen, Xu; Xu, Nan; Wang, Yonghong

    2013-10-01

    High accuracy full field three dimensional (3D) deformation measurements have always been an essential problem for the manufacturing, instrument, and aerospace industry. 3D deformations, which can be translated further into 3D strain and stress, are the key parameter for design, manufacturing and quality control. Due to the fast development of the manufacturing industry, especially in the automobile and airspace industry, rapid design and optimization concepts have already widely accepted. These concepts all require the support of rapid, high sensitive and accuracy 3D deformation measurement. Advanced optical methods are gaining widely acceptance for deformation and stain measurement by industry due to the advantages of non-contact, full-field and high measurement sensitivity. Of these methods, Electronic Speckle Pattern Interferometry (ESPI) is the most sensitive and accurate method for 3D deformation measurement in micro and sub micro-level. ESPI measures deformation by evaluating the phase difference of two recorded speckle interferograms under different loading conditions. Combined with a phase shift technique, ESPI systems can measure the 3D deformation with dozens of nanometer level sensitivity. Cataloged by phase calculation methods, ESPI systems can be divided into temporal phase shift ESPI systems and spatial phase shift ESPI system. This article provides a review and a comparison of temporal and spatial phase shift speckle pattern interferometry for 3D deformation measurement. After an overview of the fundamentals of ESPI theory, temporal phase-shift and spatial phase-shift techniques, 3D deformation measurements by the temporal phase-shift ESPI which is suited well for static measurement and by the spatial phase-shift ESPI which is particularly useful for dynamic measurement will be discussed in detail. Basic theory, brief derivation and different optical layouts for the two systems will be presented. The potentials and limitations of the both ESPI

  15. Absolute distance measurement by multi-heterodyne interferometry using a frequency comb and a cavity-stabilized tunable laser.

    PubMed

    Wu, Hanzhong; Zhang, Fumin; Liu, Tingyang; Balling, Petr; Qu, Xinghua

    2016-05-20

    In this paper, we develop a multi-heterodyne system capable of absolute distance measurement using a frequency comb and a tunable diode laser locked to a Fabry-Perot cavity. In a series of subsequent measurements, numerous beat components can be obtained by downconverting the optical frequency into the RF region with multi-heterodyne interferometry. The distances can be measured via the mode phases with a series of synthetic wavelengths. The comparison with the reference interferometer shows an agreement within 1.5 μm for the averages of five measurements and 2.5 μm for the single measurement, which is at the 10-8 relative precision level. PMID:27411152

  16. Method based on chirp decomposition for dispersion mismatch compensation in precision absolute distance measurement using swept-wavelength interferometry.

    PubMed

    Lu, Cheng; Liu, Guodong; Liu, Bingguo; Chen, Fengdong; Hu, Tao; Zhuang, Zhitao; Xu, Xinke; Gan, Yu

    2015-12-14

    We establish a theoretical model of dispersion mismatch in absolute distance measurements using swept-wavelength interferometry (SWI) and propose a novel dispersion mismatch compensation method called chirp decomposition. This method separates the dispersion coefficient and distance under test, which ensures dispersion mismatch compensation without introducing additional random errors. In the measurement of a target located at 3.9 m, a measurement resolution of 45.9 μm is obtained, which is close to the theoretical resolution, and a standard deviation of 0.74 μm is obtained, which is better than the traditional method. The measurement results are compared to a single-frequency laser interferometer. The target moves from 1 m to 3.7 m, and the measurement precision using the new method is less than 0.81 μm. PMID:26698959

  17. Real-time displacement measurement system using phase-shifted optical pulse interferometry: Application to a seismic observation system

    NASA Astrophysics Data System (ADS)

    Yoshida, Minoru; Hirayama, Yoshiharu; Takahara, Atsushi; Kashi, Motofumi; Takeuchi, Keiji; Ikeda, Toshiharu; Hirai, Fumio; Mizuno, Yosuke; Nakamura, Kentaro; Kimura, Hitoshi; Ino, Norio; Inoue, Wataru

    2016-02-01

    We developed a method of detecting incident light levels on the oscillator surfaces and light pulses that include two interfering pulses with a phase shift of π/2 (phase-shifted optical pulse interferometry). This system enables the measurement of displacements greatly exceeding the half wavelength of the laser. Moreover, it allows measurements at multiple locations with a single optical fiber for using optical pulses. In this study, we conducted an interference experiment using 30 ns optical pulses and transmitted them at 1 µs intervals. We confirmed that the above two measurements are possible. Furthermore, from the data of the oscillator used for verification, we showed that measurements on the order of nanometers are possible. Since this method does not require a power supply to the oscillator, its widespread applications in physical exploration can be expected.

  18. Large-scale deformation of Tibet measured with Envisat ScanSAR interferometry

    NASA Astrophysics Data System (ADS)

    Fielding, E. J.; Rosen, P. A.; Burgmann, R.

    2007-12-01

    Scanning synthetic aperture radar (ScanSAR) interferometry has the potential to map deformation over large areas. The large actively deforming area and arid climate of Tibet make it an excellent test area for the ScanSAR interferometry technique, which has been proposed as a possible SAR operation mode for the DESDynI mission recommended by the Decadal Survey. The Envisat C-band (5.6 cm wavelength) ScanSAR is called Wide Swath (WS) mode and images a track that is over 400 km wide, with five subswaths. Envisat WS was not originally designed for interferometry, but about one in five pairs have the required burst synchronization. Since January 2007, the European Space Agency have been attempting to greatly improve the burst synchronization and reduce the variation in baselines. Unfortunately, some of the WS data over Tibet has been acquired in HH polarization and some in VV polarization, causing an additional limitation on usable interferometric pairs. Several Envisat tracks across Tibet have appropriate WS acquisitions to form interferometric pairs. Initial results show a reduction of coherence in eastern Tibet where the plateau climate is wetter and allows more vegetation cover. Processing long strips (>1000 km) with the full WS width gives strong constraints on the baseline between the two orbits of image-pair acquisitions and enables better separation of atmospheric effects and orbit errors from moderate- wavelength (~ 100 km) deformation signals. Long-wavelength control from GPS or other ground-based data is still required for the longest wavelengths (>300 km).

  19. Temperature measurement of axisymmetric flames under the influence of magnetic field using Talbot interferometry

    SciTech Connect

    Agarwal, Shilpi E-mail: manojklakra@gmail.com Kumar, Manoj E-mail: manojklakra@gmail.com Shakher, Chandra E-mail: manojklakra@gmail.com

    2014-10-15

    Combustion process control is related with ecological improvement and the problem of energy efficiency; hence it has a wide interest at both economical and scientific levels. Application of a magnetic field is one of the most promising methods of combustion control. The presence of magnetic field induces the changes in flame behavior. The effect of uniform magnetic field developed by permanent magnet is studied by Talbot interferometry using circular gratings. Experimental results show a small decrease in flame temperature and increase in flame dimensions.

  20. Measurement of fluid properties using rapid-double-exposure and time-average holographic interferometry

    SciTech Connect

    Decker, A.J.

    1984-06-01

    The holographic recording of the time history of a flow feature in three dimensions is discussed. The use of diffuse illumination holographic interferometry or the three dimensional visualization of flow features such as shock waves and turbulent eddies is described. The double-exposure and time-average methods are compared using the characteristic function and the results from a flow simulator. A time history requires a large hologram recording rate. Results of holographic cinematography of the shock waves in a flutter cascade are presented as an example. Future directions of this effort, including the availability and development of suitable lasers, are discussed.

  1. Automatic Fringe Detection for Oil Film Interferometry Measurement of Skin Friction

    NASA Technical Reports Server (NTRS)

    Naughton, Jonathan W.; Decker, Robert K.; Jafari, Farhad

    2001-01-01

    This report summarizes two years of work on investigating algorithms for automatically detecting fringe patterns in images acquired using oil-drop interferometry for the determination of skin friction. Several different analysis methods were tested, and a combination of a windowed Fourier transform followed by a correlation was found to be most effective. The implementation of this method is discussed and details of the process are described. The results indicate that this method shows promise for automating the fringe detection process, but further testing is required.

  2. Measurement of fluid properties using rapid-double-exposure and time-average holographic interferometry

    NASA Technical Reports Server (NTRS)

    Decker, A. J.

    1984-01-01

    The holographic recording of the time history of a flow feature in three dimensions is discussed. The use of diffuse illumination holographic interferometry or the three dimensional visualization of flow features such as shock waves and turbulent eddies is described. The double-exposure and time-average methods are compared using the characteristic function and the results from a flow simulator. A time history requires a large hologram recording rate. Results of holographic cinematography of the shock waves in a flutter cascade are presented as an example. Future directions of this effort, including the availability and development of suitable lasers, are discussed.

  3. Measurement of fluid properties using rapid-double-exposure and time-average holographic interferometry

    NASA Technical Reports Server (NTRS)

    Decker, A. J.

    1984-01-01

    The holographic recording of the time history of a flow feature in three dimensions is discussed. The use of diffuse illumination holographic interferometry or the three-dimensional visualization of flow features such as shock waves and turbulent eddies is described. The double-exposure and time-average methods are compared using the characteristic function and the results from a flow simulator. A time history requires a large hologram recording rate. Results of holographic cinematography of the shock waves in a flutter cascade are presented as an example. Future directions of this effort, including the availability and development of suitable lasers, are discussed. Previously announced in STAR as N84-21849

  4. Multi-wavelength phase-shifting interferometry for micro-structures measurement based on color image processing in white light interference

    NASA Astrophysics Data System (ADS)

    Guo, Tong; Li, Feng; Chen, Jinping; Fu, Xing; Hu, Xiaotang

    2016-07-01

    Conventional multi-wavelength phase-shifting interferometry utilizes two or three monochromatic light sources, such as lasers, to realize the measurement of the surface topography with large discontinuity. In this paper, the white light source, with a single-chip CCD color camera, is used to accomplish multi-wavelength phase-shifting interferometry. In addition, we propose an algorithm which combines white light phase-shifting algorithm, equivalent wavelength method and fringe order method to achieve measuring and calibrating the micro-structures ranging from nanometer scale to micrometer scale. Finally, the proposed method is validated by a traceable step height standard.

  5. Living cell dry mass measurement using quantitative phase imaging with quadriwave lateral shearing interferometry: an accuracy and sensitivity discussion

    NASA Astrophysics Data System (ADS)

    Aknoun, Sherazade; Savatier, Julien; Bon, Pierre; Galland, Frédéric; Abdeladim, Lamiae; Wattellier, Benoit; Monneret, Serge

    2015-12-01

    Single-cell dry mass measurement is used in biology to follow cell cycle, to address effects of drugs, or to investigate cell metabolism. Quantitative phase imaging technique with quadriwave lateral shearing interferometry (QWLSI) allows measuring cell dry mass. The technique is very simple to set up, as it is integrated in a camera-like instrument. It simply plugs onto a standard microscope and uses a white light illumination source. Its working principle is first explained, from image acquisition to automated segmentation algorithm and dry mass quantification. Metrology of the whole process, including its sensitivity, repeatability, reliability, sources of error, over different kinds of samples and under different experimental conditions, is developed. We show that there is no influence of magnification or spatial light coherence on dry mass measurement; effect of defocus is more critical but can be calibrated. As a consequence, QWLSI is a well-suited technique for fast, simple, and reliable cell dry mass study, especially for live cells.

  6. Visual measurement of the evaporation process of a sessile droplet by dual-channel simultaneous phase-shifting interferometry

    PubMed Central

    Sun, Peng; Zhong, Liyun; Luo, Chunshu; Niu, Wenhu; Lu, Xiaoxu

    2015-01-01

    To perform the visual measurement of the evaporation process of a sessile droplet, a dual-channel simultaneous phase-shifting interferometry (DCSPSI) method is proposed. Based on polarization components to simultaneously generate a pair of orthogonal interferograms with the phase shifts of π/2, the real-time phase of a dynamic process can be retrieved with two-step phase-shifting algorithm. Using this proposed DCSPSI system, the transient mass (TM) of the evaporation process of a sessile droplet with different initial mass were presented through measuring the real-time 3D shape of a droplet. Moreover, the mass flux density (MFD) of the evaporating droplet and its regional distribution were also calculated and analyzed. The experimental results show that the proposed DCSPSI will supply a visual, accurate, noncontact, nondestructive, global tool for the real-time multi-parameter measurement of the droplet evaporation. PMID:26178451

  7. Comparison of Plasma Density Measurements in ICP Discharges Using Langmuir Probe, Plasma Oscillation Probe and Interferometry Techniques

    NASA Astrophysics Data System (ADS)

    Evans, John; Zawalski, Wade; Chen, Francis

    2000-10-01

    A comparison study of the application of various probe theories, including the so-called orbital motion limited (OML) and ABR theories, in the interpretation of Langmuir probe I-V characteristics is performed. Experimental data for the comparison is obtained in an inductively coupled plasma (ICP) source over a wide range of parameters of interest to the plasma processing community. Measurements of Ni from the Hiden Electrostatic Plasma Probe (ESP) characteristics and software are compared to ``known" values of Ne obtained via microwave interferometry and the plasma oscillation probe (POP) technique, in regimes including those where the probe theories yield different results. Excellent agreement is obtained between the interferometry and POP methods at low Po, whereas POP starts to fail at Po>5 mTorr, as expected. Langmuir probe results using OML theory yield reasonable agreement for Ne<2x1011cm-3, but fail at higher Ne. Closely spaced multiple peaks in the spectra of the POP are observed in some cases at higher RF input powers, possibly due to RF modulation of the source plasma density, leading to experimental uncertainty in Ne values thus obtained. Other considerations for the applicability of the POP method will also be discussed.

  8. Comparative measurements of natural convection heat transfer in channels by holographic interferometry and schlieren

    NASA Astrophysics Data System (ADS)

    Ambrosini, Dario; Tanda, Giovanni

    2006-01-01

    In this work, natural convection heat transfer in vertical channels is experimentally investigated by applying different optical techniques, namely holographic interferometry and schlieren. Both these techniques are based on the temperature dependence of the air refractive index but they detect different optical quantities and their use involves different instrumentation and optical components. Optical methods, non-intrusive in nature, are particularly suitable for the visualization of flow and thermal fields as witnessed by their increasing use in a range of scientific and engineering disciplines; for this reason, the introduction of these experimental tools into a laboratory course can be of high value. Physics and engineering students can get familiarized with optical techniques, grasp the basics of thermal phenomena, usually elusive, which can be more easily understood if they are made visible, and begin to master digital image analysis, a key skill in laboratory activities. A didactic description of holographic interferometry and schlieren is provided and experimental results obtained for vertical, smooth and rib-roughened channels with asymmetrical heating are presented. A comparison between distributions of the local heat transfer coefficient (or its dimensionless counterpart, the Nusselt number) revealed good agreement between the results separately obtained by the two techniques, thus proving their suitability for investigating free convection heat transfer in channels.

  9. Measurement of temperature and temperature distribution in gaseous flames by digital speckle pattern shearing interferometry using holographic optical element

    NASA Astrophysics Data System (ADS)

    Kumar, Manoj; Shakher, Chandra

    2015-10-01

    Digital speckle pattern lateral shear interferometry (DSPSI) based on volume phase holographic grating for the measurement of temperature and temperature distribution in candle flames is presented. The DSPSI setup uses the volume phase holographic grating combined with ground glass to shear the wavefronts. The shear of the two wavefronts is controlled by the distance between volume phase holographic grating and the ground glass. The sheared wavefronts on the ground glass are imaged onto the CMOS detector by an imaging lens. Two specklegrams are recorded corresponding to the absence of the flame and the presence of the flame. The fringe pattern is observed by subtracting these two specklegrams. A single fringe pattern was used to extract phase by the application of Riesz transform and the monogenic signal. The measured values of the temperature of the candle flame by DSPSI is compared with that of R-type Platinum-Platinum Rhodium thermocouple and the results are well within experimental limits.

  10. Synthetic aperture double exposure digital holographic interferometry for wide angle measurement and monitoring of mechanical displacements

    NASA Astrophysics Data System (ADS)

    Kujawinska, M.; Makowski, P.; Finke, G.; Zak, J.; Józwik, M.; Kozacki, T.

    2015-08-01

    A novel approach for wide angle registration and display of double exposure digital holograms of 3D objects under static or step-wise load is presented. The registration setup concept combines digital Fourier holography with synthetic aperture (SA) technique, which is equivalent to usage of a wide angle, spherically curved detector. The coherent object wavefields extracted from a pair of acquisitions collected in the synthetic aperture double exposure digital holographic interferometry scheme (SA DEDH) are utilized as the input for two different scenarios of investigation, which include (i) numerical determination of 2D phase difference fringes representing deformation of an object and (ii) physical displaying of a 3D image resulting from interference of two object (slightly different) wavefronts registered at the SA double exposure hologram. The capture and display processes are analyzed and implemented. The applicability of both numerical and experimental approach to SA DEDH for testing engineering objects is discussed.

  11. Geodetic and Astrometric Measurements with Very-Long-Baseline Interferometry. Ph.D. Thesis - MIT

    NASA Technical Reports Server (NTRS)

    Robertson, D. S.

    1975-01-01

    The use of very-long-baseline interferometry (VLBI) observations for the estimation of geodetic and astrometric parameters is discussed. Analytic models for the dependence of delay and delay rate on these parameters are developed and used for parameter estimation by the method of weighted least squares. Results are presented from approximately 15,000 delay and delay-rate observations, obtained in a series of nineteen VLBI experiments involving a total of five stations on two continents. The closure of baseline triangles is investigated and found to be consistent with the scatter of the various baseline-component results. Estimates are made of the wobble of the earth's pole and of the irregularities in the earth's rotation rate. Estimates are also made of the precession constant and of the vertical Love number, for which a value of 0.55 + or - 0.05 was obtained.

  12. Implications of very long baseline interferometry measurements on North American intra-plate crustal deformation

    NASA Technical Reports Server (NTRS)

    Allenby, R. J.

    1979-01-01

    Very Long Baseline Interferometry experiments over the last 1-3/4 years between Owens Valley, CA and Haystack, MA Radio Observatories suggest an upper limit of east-west crustal deformation between the two sites of about 1 cm/yr. In view of the fact that the baseline between the two sites traverses most of the major geological provinces of the United States, this low rate of crustal deformation has direct relevance to intra-plate crustal tectonics. The most active region traversed by this baseline is the Basin and Range province, which was estimated by various researchers to be expanding in an east-west direction at rates of .3 to 1.5 cm/yr. The Colorado Plateau and Rocky Mountain system also appear to be expanding, but at a somewhat lower rate, while east of the Rocky Mountains, the predominant stress appears to be compressional, nearly horizontal, and east to northeast trending.

  13. A new approach to the measurement of protein solubility by Michaelson interferometry

    NASA Astrophysics Data System (ADS)

    Gray, R. J.; Hou, W. B.; Kudryavtsev, A. B.; DeLucas, L. J.

    2001-11-01

    Protein concentration influences nucleation and crystal growth rates, therefore an appropriate degree of supersaturation is essential for the preparation of large and good quality crystals. Knowledge of a protein's solubility dependence on solution variables such as temperature, pH, or ionic strength can be very useful for defining optimum conditions for protein crystal growth work. We have refined a Michaelson interferometry technique reported by Sazaki et al. (J. Crystal Growth 169 (1996) 355.) for determination of protein solubility using the proteins lysozyme and equine serum albumin by examining the behavior of both surface and concentration gradient fringes. This has provided a sensitive and accurate estimate of protein solubility using small crystals (0.2 mm×0.1 mm).

  14. Synthetic Aperture Radar Interferometry to Measure Earth's Surface Topography and Its Deformation

    NASA Astrophysics Data System (ADS)

    Bürgmann, Roland; Rosen, Paul A.; Fielding, Eric J.

    Synthetic aperture radar interferometry (InSAR) from Earth-orbiting spacecraft provides a new tool to map global topography and deformation of the Earth's surface. Radar images taken from slightly different viewing directions allow the construction of digital elevation models of meter-scale accuracy. These data sets aid in the analysis and interpretation of tectonic and volcanic landscapes. If the Earth's surface deformed between two radar image acquisitions, a map of the surface displacement with tens-of-meters resolution and subcentimeter accuracy can be constructed. This review gives a basic overview of InSAR for Earth scientists and presents a selection of geologic applications that demonstrate the unique capabilities of InSAR for mapping the topography and deformation of the Earth.

  15. Measurement of dynamic patterns of an elastic membrane at bi-modal vibration using high speed electronic speckle pattern interferometry

    SciTech Connect

    Preciado, Jorge Sanchez; Lopez, Carlos Perez; Santoyo, Fernando Mendoza

    2014-05-27

    Implementing a hybrid arrangement of Laser Doppler Vibrometry (LDV) and high speed Electronic Speckle Pattern Interferometry (ESPI) we were able to measure the dynamic patterns of a flat rectangular elastic membrane clamped at its edges stimulated with the sum of two resonance frequencies. ESPI is a versatile technique to analyze in real-time the deformation of a membrane since its low computational cost and easy implementation of the optical setup. Elastic membranes present nonlinear behaviors when stimulated with low amplitude signals. The elastic membrane under test, with several non rational related vibrating modals below the 200 Hz, was stimulated with two consecutives resonant frequencies. The ESPI patterns, acquired at high speed rates, shown a similar behavior for the dual frequency stimulation as in the case of patterns formed with the entrainment frequency. We think this may be related to the effects observed in the application of dual frequency stimulation in ultrasound.

  16. Iris as a reflector for differential absorption low-coherence interferometry to measure glucose level in the anterior chamber

    NASA Astrophysics Data System (ADS)

    Zhou, Yong; Zeng, Nan; Ji, Yanhong; Li, Yao; Dai, Xiangsong; Li, Peng; Duan, Lian; Ma, Hui; He, Yonghong

    2011-01-01

    We present a method of glucose concentration detection in the anterior chamber with a differential absorption optical low-coherent interferometry (LCI) technique. Back-reflected light from the iris, passing through the anterior chamber twice, was selectively obtained with the LCI technique. Two light sources, one centered within (1625 nm) and the other centered outside (1310 nm) of a glucose absorption band were used for differential absorption measurement. In the eye model and pig eye experiments, we obtained a resolution glucose level of 26.8 mg/dL and 69.6 mg/dL, respectively. This method has a potential application for noninvasive detection of glucose concentration in aqueous humor, which is related to the glucose concentration in blood.

  17. Simultaneous measurement of refractive index and wedge angle of optical windows using Fizeau interferometry and a cyclic path optical configuration

    SciTech Connect

    Kumar, Y. Pavan; Chatterjee, Sanjib

    2009-08-20

    We present a new technique for the simultaneous measurement of refractive index and wedge angle of optical windows using Fizeau interferometry and a cyclic path optical configuration (CPOC). Two laterally separated beams are obtained from an expanded collimated beam using an aperture containing two rectangular openings. The test wedge plate is placed in one of the two separated beams. Using CPOC, these two beams are made to overlap and interfere, producing interference fringes in the overlapping region. The beams reflected from the front and back surfaces of the test wedge plate interfere and produce Fizeau fringes. The refractive index is related to the spacing of the above two beam fringes. The wedge angle is determined from the evaluated values of the refractive index and Fizeau fringe spacing. The results obtained for a BK-7 optical window are presented.

  18. Analysis of the feasibility of an experiment to measure carbon monoxide in the atmosphere. [using remote platform interferometry

    NASA Technical Reports Server (NTRS)

    Bortner, M. H.; Alyea, F. N.; Grenda, R. N.; Liebling, G. R.; Levy, G. M.

    1973-01-01

    The feasibility of measuring atmospheric carbon monoxide from a remote platform using the correlation interferometry technique was considered. It has been determined that CO data can be obtained with an accuracy of 10 percent using this technique on the first overtone band of CO at 2.3 mu. That band has been found to be much more suitable than the stronger fundamental band at 4.6 mu. Calculations for both wavelengths are presented which illustrate the effects of atmospheric temperature profiles, inversion layers, ground temperature and emissivity, CO profile, reflectivity, and atmospheric pressure. The applicable radiative transfer theory on which these calculations are based is described together with the principles of the technique.

  19. Study of non-contact measurement of the thermal expansion coefficients of materials based on laser feedback interferometry

    SciTech Connect

    Zheng, Fasong; Tan, Yidong; Zhang, Shulian; Lin, Jing; Ding, Yingchun

    2015-04-15

    The noncooperative and ultrahigh sensitive length measurement approach is of great significance to the study of a high-precision thermal expansion coefficient (TEC) determination of materials at a wide temperature range. The novel approach is presented in this paper based on the Nd:YAG microchip laser feedback interferometry with 1064 nm wavelength, the beam frequency of which is shifted by a pair of acousto-optic modulators and then the heterodyne phase measurement technique is used. The sample is placed in a muffle furnace with two coaxial holes opened on the opposite furnace walls. The measurement beams are perpendicular and coaxial on each surface of the sample, the configuration which can not only achieve the length measurement of sample but also eliminate the influence of the distortion of the sample supporter. The reference beams inject on the reference mirrors which are put as possible as near the holes, respectively, to eliminate the air disturbances and the influence of thermal lens effect out of the furnace chamber. For validation, the thermal expansion coefficients of aluminum and steel 45 samples are measured from room temperature to 748 K, which proved measurement repeatability of TECs is better than 0.6 × 10{sup −6}(K{sup −1}) at the range of 298 K–598 K and the high-sensitive non-contact measurement of the low reflectivity surface induced by the oxidization of the samples at the range of 598 K–748 K.

  20. Study of non-contact measurement of the thermal expansion coefficients of materials based on laser feedback interferometry

    NASA Astrophysics Data System (ADS)

    Zheng, Fasong; Tan, Yidong; Lin, Jing; Ding, Yingchun; Zhang, Shulian

    2015-04-01

    The noncooperative and ultrahigh sensitive length measurement approach is of great significance to the study of a high-precision thermal expansion coefficient (TEC) determination of materials at a wide temperature range. The novel approach is presented in this paper based on the Nd:YAG microchip laser feedback interferometry with 1064 nm wavelength, the beam frequency of which is shifted by a pair of acousto-optic modulators and then the heterodyne phase measurement technique is used. The sample is placed in a muffle furnace with two coaxial holes opened on the opposite furnace walls. The measurement beams are perpendicular and coaxial on each surface of the sample, the configuration which can not only achieve the length measurement of sample but also eliminate the influence of the distortion of the sample supporter. The reference beams inject on the reference mirrors which are put as possible as near the holes, respectively, to eliminate the air disturbances and the influence of thermal lens effect out of the furnace chamber. For validation, the thermal expansion coefficients of aluminum and steel 45 samples are measured from room temperature to 748 K, which proved measurement repeatability of TECs is better than 0.6 × 10-6(K-1) at the range of 298 K-598 K and the high-sensitive non-contact measurement of the low reflectivity surface induced by the oxidization of the samples at the range of 598 K-748 K.

  1. Study of non-contact measurement of the thermal expansion coefficients of materials based on laser feedback interferometry.

    PubMed

    Zheng, Fasong; Tan, Yidong; Lin, Jing; Ding, Yingchun; Zhang, Shulian

    2015-04-01

    The noncooperative and ultrahigh sensitive length measurement approach is of great significance to the study of a high-precision thermal expansion coefficient (TEC) determination of materials at a wide temperature range. The novel approach is presented in this paper based on the Nd:YAG microchip laser feedback interferometry with 1064 nm wavelength, the beam frequency of which is shifted by a pair of acousto-optic modulators and then the heterodyne phase measurement technique is used. The sample is placed in a muffle furnace with two coaxial holes opened on the opposite furnace walls. The measurement beams are perpendicular and coaxial on each surface of the sample, the configuration which can not only achieve the length measurement of sample but also eliminate the influence of the distortion of the sample supporter. The reference beams inject on the reference mirrors which are put as possible as near the holes, respectively, to eliminate the air disturbances and the influence of thermal lens effect out of the furnace chamber. For validation, the thermal expansion coefficients of aluminum and steel 45 samples are measured from room temperature to 748 K, which proved measurement repeatability of TECs is better than 0.6 × 10(-6)(K(-1)) at the range of 298 K-598 K and the high-sensitive non-contact measurement of the low reflectivity surface induced by the oxidization of the samples at the range of 598 K-748 K. PMID:25933843

  2. Hot Exozodiacal Dust Disks, their Detection and Variability, as Measured with Long-Baseline Optical Interferometry.

    NASA Astrophysics Data System (ADS)

    Scott, Nicholas Jon

    2016-01-01

    Near-infrared long-baseline optical interferometry has provided the first unambiguous resolved detections of hot dust around main sequence stars (Absil et al. 2006). This showed that an unexpectedly dense population of (sub)micrometer dust grains close exists to their sublimation temperature of approximately 1400K. A later survey (Absil et al. 2013) revealed that these "hot exozodiacal disks" are relatively common around spectral type A-K stars. Current models of circumstellar debris disks suggest that in the inner region, within 1 AU, of the disk the timescale for complete removal of submicron dust is on the order of a few years (Wyatt 2008). The presence of dust close to the star is surprising because most cold debris belts detected are collisionally dominated. Mutual collisions grind the dust down to the size where radiation pressure pushes the dust out before Poynting-Robertson drag has a chance to pull the dust inward. Competing models exist to explain the persistence of this dust; some of which suggest that dust production is a punctuated and chaotic process fueled by asteroid collisions and comet infall that would show variability on timescales of a few years.High precision long-baseline interferometry observations in the K-band with the FLUOR (Fiber Linked Unit for Optical Recombination) beam combiner at the CHARA (Center for High Angular Resolution Astronomy) Array provided the data for these exozodiacal dust detections. This original instrument has undergone upgrades as part of JouFLU (Jouvence of FLUOR) project. The new instrument has been used to expand the original survey and to re-observe stars from the previous exozodiacal disk survey to search for predicted variations in the detected disks. We have found evidence that for some systems the amount of circumstellar flux from these previously detected exozodiacal disks, or exozodis, has varied greatly. The flux from some exozodis has increased, others decreased, and for a few the amount has remained

  3. Synchronous triple-optical-path digital speckle pattern interferometry with fast discrete curvelet transform for measuring three-dimensional displacements

    NASA Astrophysics Data System (ADS)

    Gu, Guoqing; Wang, Kaifu; Wang, Yanfang; She, Bin

    2016-06-01

    Digital speckle pattern interferometry (DSPI) is a well-established and widely used optical measurement technique for obtaining qualitative as well as quantitative measurements of objects deformation. The simultaneous measurement of an object's surface displacements in three dimensions using DSPI is of great interest. This paper presents a triple-optical-path DSPI based method for the simultaneous and independent measurement of three-dimensional (3D) displacement fields. In the proposed method, in-plane speckle interferometers with dual-observation geometry and an out-of-plane interferometer are optimally combined to construct an integrated triple-optical-path DSPI system employing the phase shift technique, which uses only a single laser source and three cameras. These cameras are placed along a single line to synchronously capture real-time visible speckle fringe patterns in three dimensions. In addition, a pre-filtering method based on the fast discrete curvelet transform (FDCT) is utilized for denoising the obtained wrapped phase patterns to improve measurement accuracy. Finally, the simultaneous measurement of the 3D displacement fields of a simple beam and a composite laminated plate respectively subjected to three-point and single-point bend loading are investigated to validate the feasibility and effectiveness of the proposed method.

  4. Modulated photoactivation of composite restoration: measurement of cuspal movement using holographic interferometry.

    PubMed

    Blažić, Larisa; Pantelić, Dejan; Savić-Šević, Svetlana; Murić, Branka; Belić, Ilija; Panić, Bratimir

    2011-03-01

    The purpose of this research was to investigate the influence of modulated photoactivation on cuspal movement. Eight class II MOD composite restorations were analyzed under various photoactivation protocols in a real-time manner using holographic interferometry. During the first photoactivation protocol, the composite restoration was illuminated for 200 s continuously. In the second protocol, the polymerization lamp was first turned on for 5 s, then turned off for 120 s, and again turned on for a final 195 s. In both protocols, radiant exposure was the same. A significant decrease (p < 0.05) in cuspal deflection was found for two-step irradiation (average value of total cuspal deflection was 5.03 ± 0.62 µm) compared to continuous irradiation (average value of total cuspal deflection was 5.95 ± 0.65 µm). The two-step photoactivation protocol was found preferable, since it resulted in a significantly lower cuspal deflection (11% lower, compared to the continuous illumination). PMID:20309595

  5. Measurements of deformations in osseous structures and implants by digital speckle interferometry (DSPI)

    NASA Astrophysics Data System (ADS)

    Salvador, Rosario; González-Peña, Rolando; Cibrián, Rosa; Buendía, Mateo; Mínguez, Fe; Laguía, Manuel; Molina, Teresa; Marti, Luis; Esteve, José; Caballero, José; Micó, Vicente; Sanjuan, Elena

    2006-09-01

    Knowledge of how osseous structures and implants behave under deforming stress is an interesting point when evaluating the response of an implanted prosthesis. The failure of an implant is not always due to the great stress a structure may be subjected to at a particular moment, but rather to the effects of deterioration associated with lesser stress but which is continuously applied. Therefore it is helpful to know how bones and implants respond to this lesser stress. Digital speckle interferometry (DSPI) is suitable for this type of determination, as it is a highly sensitive, non-invasive optical technique. In this study we present the results we obtained when determining the elasticity of a sample of a macerated human radius, a titanium implant and a titanium screw used to treat the fractures of this bone. The correlation ratios we obtained in determining Young's modulus were in the order of r=0.994. Models were made of these structures using the finite elements method (FEM) with the aid of the ANSYS 10.0 program, applying Young's modulus values determined by DSPI. With a view to monitoring the accuracy of the FEM models of the bone and the implant elements we designed a flexion experiment to obtain the DSPI values in and out of plane. The high degree of concordance between the results of both methods makes it possible to continue studying osseous samples with a fixed implant, and also other implants made of different alloys.

  6. Measurement of slow-moving along-track displacement from an efficient multiple-aperture SAR interferometry (MAI) stacking

    USGS Publications Warehouse

    Jo, Min-Jeong; Jung, Hyung-Sup; Won, Joong-Sun; Poland, Michael; Miklius, Asta; Lu, Zhong

    2015-01-01

    Multiple-aperture SAR interferometry (MAI) has demonstrated outstanding measurement accuracy of along-track displacement when compared to pixel-offset-tracking methods; however, measuring slow-moving (cm/year) surface displacement remains a challenge. Stacking of multi-temporal observations is a potential approach to reducing noise and increasing measurement accuracy, but it is difficult to achieve a significant improvement by applying traditional stacking methods to multi-temporal MAI interferograms. This paper proposes an efficient MAI stacking method, where multi-temporal forward- and backward-looking residual interferograms are individually stacked before the MAI interferogram is generated. We tested the performance of this method using ENVISAT data from Kīlauea Volcano, Hawai‘i, where displacement on the order of several centimeters per year is common. By comparing results from the proposed stacking methods with displacements from GPS data, we documented measurement accuracies of about 1.03 and 1.07 cm/year for the descending and ascending tracks, respectively—an improvement of about a factor of two when compared with that from the conventional stacking approach. Three-dimensional surface-displacement maps can be constructed by combining stacked InSAR and MAI observations, which will contribute to a better understanding of a variety of geological phenomena.

  7. Measurement of slow-moving along-track displacement from an efficient multiple-aperture SAR interferometry (MAI) stacking

    NASA Astrophysics Data System (ADS)

    Jo, Min-Jeong; Jung, Hyung-Sup; Won, Joong-Sun; Poland, Michael P.; Miklius, Asta; Lu, Zhong

    2015-05-01

    Multiple-aperture SAR interferometry (MAI) has demonstrated outstanding measurement accuracy of along-track displacement when compared to pixel-offset-tracking methods; however, measuring slow-moving (cm/year) surface displacement remains a challenge. Stacking of multi-temporal observations is a potential approach to reducing noise and increasing measurement accuracy, but it is difficult to achieve a significant improvement by applying traditional stacking methods to multi-temporal MAI interferograms. This paper proposes an efficient MAI stacking method, where multi-temporal forward- and backward-looking residual interferograms are individually stacked before the MAI interferogram is generated. We tested the performance of this method using ENVISAT data from Kīlauea Volcano, Hawai`i, where displacement on the order of several centimeters per year is common. By comparing results from the proposed stacking methods with displacements from GPS data, we documented measurement accuracies of about 1.03 and 1.07 cm/year for the descending and ascending tracks, respectively—an improvement of about a factor of two when compared with that from the conventional stacking approach. Three-dimensional surface-displacement maps can be constructed by combining stacked InSAR and MAI observations, which will contribute to a better understanding of a variety of geological phenomena.

  8. Evaluation of the uncertainty of phase-difference measurements in (quasi-)Fourier transform digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Doval, Ángel F.; Trillo, Cristina; López Vázquez, José Carlos; Fernández, José L.

    2015-08-01

    Estimation of the uncertainty is an essential requisite for high-end measurement systems. In this communication we derive an expression to evaluate the standard uncertainty of the phase-difference measurements resulting from Fourier and quasi-Fourier transform digital holographic interferometry. We apply the law of propagation of uncertainty, as defined in the "Guide to the expression of uncertainty in measurement" (GUM), to the digital reconstruction of two holograms by Fourier transformation and to the subsequent calculation of the phase change between the holographic reconstructions. The resulting expression allows the evaluation of the uncertainty of the phase difference at every pixel in the reconstruction plane in terms of the measured hologram brightness values and their uncertainty at the whole of the pixels of the original digital holograms. This expression is simplified by assuming a linear dependence between the uncertainty and the local value of the original holograms; in that case, the local uncertainty of the phase difference can be evaluated from the local complex values of the reconstructed holograms. We assess the behavior of the method by comparing the predicted standard uncertainty with the sample variance obtained from experiments conducted under repeatability conditions, and found a good correlation between both quantities. This experimental procedure can be also used to calibrate the parameters of the linear function relating the uncertainty with the local value of the digital holograms, for a given set of operational conditions of the acquisition device.

  9. Compact sensor combining digital speckle pattern interferometry and the hole-drilling technique to measure nonuniform residual stress fields

    NASA Astrophysics Data System (ADS)

    Viotti, Matías R.; Albertazzi, Armando

    2013-10-01

    A portable device to essentially measure residual stress fields outside an optical bench is presented. This system combines the hole-drilling technique with digital speckle pattern interferometry. A novel feature of this device is its high degree of compaction since only one base supports simultaneously the measurement module and the hole-drilling device. A new version of the American society for testing and materials standard E837 for the measurement of residual stresses has been improved including a computation method for nonuniform residual stresses. According to this standard, a hole with a maximum depth of 1.0 mm should be introduced into the material to assess the stress distribution along the hole's depth. The discretization of the stress distribution is performed in 20 equal steps of 0.05 mm, getting the deformations generated for stress relief in every drilling step. A description of the compact device showing the solution for a fast and easy interchanging process between modules is also presented. The proposed system was compared with a traditional method using strain gages, and a good agreement was shown between stress distributions measured with both methods. Finally, the portable device was used to evaluate the residual stress distribution in a sample with a rod welded by friction hydro pillar processing.

  10. Digitally Enhanced Heterodyne Interferometry

    NASA Technical Reports Server (NTRS)

    Shaddock, Daniel; Ware, Brent; Lay, Oliver; Dubovitsky, Serge

    2010-01-01

    Spurious interference limits the performance of many interferometric measurements. Digitally enhanced interferometry (DEI) improves measurement sensitivity by augmenting conventional heterodyne interferometry with pseudo-random noise (PRN) code phase modulation. DEI effectively changes the measurement problem from one of hardware (optics, electronics), which may deteriorate over time, to one of software (modulation, digital signal processing), which does not. DEI isolates interferometric signals based on their delay. Interferometric signals are effectively time-tagged by phase-modulating the laser source with a PRN code. DEI improves measurement sensitivity by exploiting the autocorrelation properties of the PRN to isolate only the signal of interest and reject spurious interference. The properties of the PRN code determine the degree of isolation.

  11. Positioning the actual interference fringe pattern on the tooth flank in measuring gear tooth flanks by laser interferometry

    NASA Astrophysics Data System (ADS)

    Fang, Suping; Wang, Leijie; Liu, Shiqiao; Komori, Masaharu; Kubo, Aizoh

    2011-05-01

    In measuring form deviation of gear tooth flanks by laser interferometry, the collected interference fringe pattern (IFP) is badly distorted, in the case of shape, relative to the actual tooth flank. Meanwhile, a clear and definite mapping relationship between the collected IFP and the actual tooth flank is indispensable for both transforming phase differences into deviation values and positioning the measurement result on the actual tooth flank. In order to solve these problems, this paper proposes a method using the simulation tooth image as a bridge connecting the actual tooth flank and the collected IFP. The mapping relationship between the simulation tooth image and the actual tooth flank has been obtained by ray tracing methods [Fang et al., Appl. Opt. 49(33), 6409-6415 (2010)]. This paper mainly discusses how to build the relationship between the simulation tooth image and the collected IFP by using a matching algorithm of two characteristic point sets. With the combination of the two above-mentioned assistant mapping relationships, the mapping relationship between the collected IFP and the actual tooth flank can be built; the collected IFP can be positioned on the actual tooth flank. Finally, the proposed method is employed in a measurement of the form deviation of a gear tooth flank and the result proves the feasibility of the proposed method.

  12. Study of the Earth’s interior using measurements of sound velocities in minerals by ultrasonic interferometry

    NASA Astrophysics Data System (ADS)

    Li, Baosheng; Liebermann, Robert C.

    2014-08-01

    This paper reviews the progress of the technology of ultrasonic interferometry from the early 1950s to the present day. During this period of more than 60 years, sound wave velocity measurements have been increased from at pressures less than 1 GPa and temperatures less than 800 K to conditions above 25 GPa and temperatures of 1800 K. This is complimentary to other direct methods to measure sound velocities (such as Brillouin and impulsive stimulated scattering) as well as indirect methods (e.g., resonance ultrasound spectroscopy, static or shock compression, inelastic X-ray scattering). Newly-developed pressure calibration methods and data analysis procedures using a finite strain approach are described and applied to data for the major mantle minerals. The implications for the composition of the Earth’s mantle are discussed. The state-of-the-art ultrasonic experiments performed in conjunction with synchrotron X-radiation can provide simultaneous measurements of the elastic bulk and shear moduli and their pressure and temperature derivatives with direct determination of pressure. The current status and outlook/challenges for future experiments are summarized.

  13. Simultaneous measurement of changes in thickness and refractive index of weakly absorbing self-standing solid films using optical interferometry

    NASA Astrophysics Data System (ADS)

    Easwar, N.; Fantini, R.; Willis, E.

    2001-06-01

    A nondestructive optical interferometric method, which enables a direct and simultaneous measurement of small changes in both thickness and refractive index of thin films, is described. Optical interferometric methods are sensitive to the changes in the optical path length (the product of the refractive index and the physical thickness) through the film. Thus, when the film is subjected to changing environmental conditions such as changing temperature or humidity, it is a challenge to determine the change in thickness and the change in refractive index separately, using interferometry. By simultaneously monitoring two different sets of interference fringes, i.e., transmission and reflection fringes, we have been able to successfully address this challenge. Our measurements on well-characterized pedigree glass samples are presented. The results agree well with the expected values for these samples, supporting the feasibility of this characterization technique to new materials. Self-standing, transparent (weakly absorbing) films ranging in thickness from tens to hundreds of microns can be characterized from direct measurements.

  14. Compensation method for obtaining accurate, sub-micrometer displacement measurements of immersed specimens using electronic speckle interferometry

    PubMed Central

    Fazio, Massimo A.; Bruno, Luigi; Reynaud, Juan F.; Poggialini, Andrea; Downs, J. Crawford

    2012-01-01

    We proposed and validated a compensation method that accounts for the optical distortion inherent in measuring displacements on specimens immersed in aqueous solution. A spherically-shaped rubber specimen was mounted and pressurized on a custom apparatus, with the resulting surface displacements recorded using electronic speckle pattern interferometry (ESPI). Point-to-point light direction computation is achieved by a ray-tracing strategy coupled with customized B-spline-based analytical representation of the specimen shape. The compensation method reduced the mean magnitude of the displacement error induced by the optical distortion from 35% to 3%, and ESPI displacement measurement repeatability showed a mean variance of 16 nm at the 95% confidence level for immersed specimens. The ESPI interferometer and numerical data analysis procedure presented herein provide reliable, accurate, and repeatable measurement of sub-micrometer deformations obtained from pressurization tests of spherically-shaped specimens immersed in aqueous salt solution. This method can be used to quantify small deformations in biological tissue samples under load, while maintaining the hydration necessary to ensure accurate material property assessment. PMID:22435090

  15. A comparison of planar, laser-induced fluorescence, and high-sensitivity interferometry techniques for gas-puff nozzle density measurements

    SciTech Connect

    Jackson, S. L.; Weber, B. V.; Mosher, D.; Phipps, D. G.; Stephanakis, S. J.; Commisso, R. J.; Qi, N.; Failor, B. H.; Coleman, P. L.

    2008-10-15

    The distribution of argon gas injected by a 12-cm-diameter triple-shell nozzle was characterized using both planar, laser-induced fluorescence (PLIF) and high-sensitivity interferometry. PLIF is used to measure the density distribution at a given time by detecting fluorescence from an acetone tracer added to the gas. Interferometry involves making time-dependent, line-integrated gas density measurements at a series of chordal locations that are then Abel inverted to obtain the gas density distribution. Measurements were made on nominally identical nozzles later used for gas-puff Z-pinch experiments on the Saturn pulsed-power generator. Significant differences in the mass distributions obtained by the two techniques are presented and discussed, along with the strengths and weaknesses of each method.

  16. A LISA Interferometry Primer

    NASA Technical Reports Server (NTRS)

    Thorpe, James Ira

    2010-01-01

    A key challenge for all gravitational wave detectors in the detection of changes in the fractional difference between pairs of test masses with sufficient precision to measure astrophysical strains with amplitudes on the order of approx.10(exp -21). ln the case of the five million km arms of LISA, this equates to distance measurements on the ten picometer level. LISA interferometry utilizes a decentralized topology, in which each of the sciencecraft houses its own light sources, detectors, and electronics. The measurements made at each of the sciencecraft are then telemetered to ground and combined to extract the strain experienced by the constellation as a whole. I will present an overview of LISA interferometry and highlight some of the key components and technologies that make it possible.

  17. Measuring rapid ocean tidal earth orientation variations with very long baseline interferometry

    NASA Astrophysics Data System (ADS)

    Sovers, O. J.; Jacobs, C. S.; Gross, R. S.

    1993-11-01

    Ocean tidal effects on universal time and polar motion (UTPM) are investigated at four nearly diurnal (K1, P1, O1, and Q1) and four nearly semidiurnal (K2, S2, M2, and N2) frequencies by analyzing very long baseline interferometry (VLBI) data extending from 1978 to 1992. We discuss limitations of comparisons between experiment and theory for the retrograde nearly diurnal polar motion components due to their degeneracy with prograde components of the nutation model. Estimating amplitudes of contributions to the modeled VLBI observables at these eight frequencies produces a statistically highly significant improvement of 7 mm to the residuals of a fit to the observed delays. Use of such an improved UTPM model also reduces the 14-30 mm scatter of baseline lengths about a time-linear model of tectonic motion by 3-14 mm, also with high significance levels. A total of 28 UTPM ocean tidal amplitudes can be unambiguously estimated from the data, with resulting UT1 and PM magnitudes as large as 21 μs and 270 microarc seconds (μas) and formal uncertainties of the order of 0.3 μs and 5 μas for UTI and PM, respectively. Empirically determined UTPM amplitudes and phases are compared to values calculated theoretically by Gross from Seiler's global ocean tide model. The discrepancy between theory and experiment is larger by a factor of 3 for UT1 amplitudes (9 μs) than for prograde PM amplitudes (42 μas). The 14-year VLBI data span strongly attenuates the influence of mismodeled effects on estimated UTPM amplitudes and phases that are not coherent with the eight frequencies of interest. Magnitudes of coherent and quasi-coherent systematic errors are quantified by means of internal consistency tests. We conclude that coherent systematic effects are many times larger than the formal uncertainties and can be as large as 4 μs for UT1 and 60 μas for polar motion. On the basis of such realistic error estimates, 22 of the 31 fitted UTPM ocean tidal amplitudes differ from zero by

  18. Measuring rapid ocean tidal earth orientation variations with very long baseline interferometry

    NASA Technical Reports Server (NTRS)

    Sovers, O. J.; Jacobs, C. S.; Gross, R. S.

    1993-01-01

    Ocean tidal effects on universal time and polar motion (UTPM) are investigated at four nearly diurnal (K(sub 1), P(sub 1), O(sub 1), and Q(sub 1)) and four nearly semidiurnal (K(sub 2), S(sub 2), M(sub 2), and N(sub 2)) frequencies by analyzing very long baseline interferometry (VLBI) data extending from 1978 to 1992. We discuss limitations of comparisons between experiment and theory for the retograde nearly diurnal polar motion components due to their degeneracy with prograde components of the nutation model. Estimating amplitudes of contributions to the modeled VLBI observables at these eight frequencies produces a statistically highly significant improvement of 7 mm to the residuals of a fit to the observed delays. Use of such an improved UTPM model also reduces the 14-30 mm scatter of baseline lengths about a time-linear model of tectonic motion by 3-14 mm, also withhigh significance levels. A total of 28 UTPM ocean tidal amplitudes can be unambiguously estimated from the data, with resulting UTI and PM magnitudes as large as 21 micro secs and 270 microarc seconds and formal uncertainties of the order of 0.3 micro secs and 5 microarc secs for UTI and PM, respectively. Empirically determined UTPM amplitudes and phases are com1pared to values calculated theoretically by Gross from Seiler's global ocean tide model. The discrepancy between theory and experiment is larger by a factor of 3 for UTI amplitudes (9 micro secs) than for prograde PM amplitudes (42 microarc secs). The 14-year VLBI data span strongly attenuates the influence of mismodeled effects on estimated UTPM amplitudes and phases that are not coherent with the eight frequencies of interest. Magnitudes of coherent and quasi-coherent systematic errors are quantified by means of internal consistency tests. We conclude that coherent systematic effects are many times larger than the formal uncertainties and can be as large as 4 micro secs for UTI and 60 microarc secs for polar motion. On the basis of such

  19. Measurement of planar refractive index profiles with rapid variations in glass using interferometry and total variation regularized differentiation

    NASA Astrophysics Data System (ADS)

    Oven, R.

    2015-12-01

    Planar refractive index profiles with rapid variations, formed in glass, are measured with interferometry. This involves forming a bevel in the glass and orientating the fringe pattern to be normal to the bevel edge. The index profile is determined by differentiation of the phase function of the fringe pattern. The differentiation has been performed using the total variation regularization method in order to preserve rapid changes in the derivative. This new approach avoids the necessity of filtering, in order to reduce noise, in the direction perpendicular to the bevel, which would otherwise smooth out the rapid index changes. The method is assessed using a model refractive index profile that contains an index gradient of 0.24 μm-1 and is then applied practically to measure the refractive index profile of electrically poled BK7 glass. The new approach allows the sharp transition in the index between poled and unpoled glass to be observed as well as the accumulation of potassium ions beyond the poled glass region.

  20. Strain, curvature, and twist measurements in digital holographic interferometry using pseudo-Wigner-Ville distribution based method

    SciTech Connect

    Rajshekhar, G.; Gorthi, Sai Siva; Rastogi, Pramod

    2009-09-15

    Measurement of strain, curvature, and twist of a deformed object play an important role in deformation analysis. Strain depends on the first order displacement derivative, whereas curvature and twist are determined by second order displacement derivatives. This paper proposes a pseudo-Wigner-Ville distribution based method for measurement of strain, curvature, and twist in digital holographic interferometry where the object deformation or displacement is encoded as interference phase. In the proposed method, the phase derivative is estimated by peak detection of pseudo-Wigner-Ville distribution evaluated along each row/column of the reconstructed interference field. A complex exponential signal with unit amplitude and the phase derivative estimate as the argument is then generated and the pseudo-Wigner-Ville distribution along each row/column of this signal is evaluated. The curvature is estimated by using peak tracking strategy for the new distribution. For estimation of twist, the pseudo-Wigner-Ville distribution is evaluated along each column/row (i.e., in alternate direction with respect to the previous one) for the generated complex exponential signal and the corresponding peak detection gives the twist estimate.

  1. FINE-SCALE STRUCTURE OF THE QUASAR 3C 279 MEASURED WITH 1.3 mm VERY LONG BASELINE INTERFEROMETRY

    SciTech Connect

    Lu Rusen; Fish, Vincent L.; Doeleman, Sheperd S.; Crew, Geoffrey; Cappallo, Roger J.; Akiyama, Kazunori; Honma, Mareki; Algaba, Juan C.; Ho, Paul T. P.; Inoue, Makoto; Bower, Geoffrey C.; Dexter, Matt; Brinkerink, Christiaan; Chamberlin, Richard; Freund, Robert; Friberg, Per; Gurwell, Mark A.; Jorstad, Svetlana G.; Krichbaum, Thomas P.; Loinard, Laurent; and others

    2013-07-20

    We report results from five day very long baseline interferometry observations of the well-known quasar 3C 279 at 1.3 mm (230 GHz) in 2011. The measured nonzero closure phases on triangles including stations in Arizona, California, and Hawaii indicate that the source structure is spatially resolved. We find an unusual inner jet direction at scales of {approx}1 pc extending along the northwest-southeast direction (P.A. = 127 Degree-Sign {+-} 3 Degree-Sign ), as opposed to other (previously) reported measurements on scales of a few parsecs showing inner jet direction extending to the southwest. The 1.3 mm structure corresponds closely with that observed in the central region of quasi-simultaneous super-resolution Very Long Baseline Array images at 7 mm. The closure phase changed significantly on the last day when compared with the rest of observations, indicating that the inner jet structure may be variable on daily timescales. The observed new direction of the inner jet shows inconsistency with the prediction of a class of jet precession models. Our observations indicate a brightness temperature of {approx}8 Multiplication-Sign 10{sup 10} K in the 1.3 mm core, much lower than that at centimeter wavelengths. Observations with better uv coverage and sensitivity in the coming years will allow the discrimination between different structure models and will provide direct images of the inner regions of the jet with 20-30 {mu}as (5-7 light months) resolution.

  2. A novel application of speckle interferometry for the measurement of strain distributions in semi-sweet biscuits

    NASA Astrophysics Data System (ADS)

    Saleem, Q.; Wildman, R. D.; Huntley, J. M.; Whitworth, M. B.

    2003-12-01

    The spontaneous formation of cracks in biscuits following baking, also known as checking, is an issue that manufacturers would like to be able to predict and avoid. Unfortunately the mechanisms driving this phenomenon are not well understood. Speckle interferometry was used to study moisture-induced in-plane strain development in biscuits. This sensitive and non-contacting technique for measuring surface displacements has two major advantages over more commonly used methods; firstly, strains can be detected at a far higher sensitivity (down to 2 × 10-6) than previously accessible and secondly the method is a whole-field technique, enabling observation of the development of strain distributions during moisture migration. For biscuits exposed to step changes in humidity, initial strain rates of up to 10-5min-1 were measured, which decreased as the moisture content approached equilibrium, leading to an accumulated strain of ~10-2 after 48 h. Under these conditions, a homogeneous, uniform strain distribution was observed. The data were used to calculate the hygroscopic expansion coefficient, which was linearly related to moisture content and provides the necessary constitutive link between strain and biscuit moisture content needed to model biscuit checking.

  3. Analysis of direction-of-arrival aliasing for MF/HF Doppler-sorted interferometry measurements of ionospheric drift

    NASA Astrophysics Data System (ADS)

    Parkinson, M. L.; Dyson, P. L.; Smith, P. R.

    1997-05-01

    The determination of accurate direction of arrival (DOA) of echoes is paramount when performing Doppler-sorted interferometry (DSI) at MF/HF to measure the drift of ionospheric plasma. Important factors affecting the accuracy include inadequate signal-to-noise ratio (SNR) and coherency of ionospheric echoes. As the SNR deteriorates, there is an increase in the errors in the phases measured at the individual antennas of an array, and this leads to ambiguities in DOA equivalent to directional aliasing. In this paper we model this effect, the effects of Doppler-frequency aliasing, and the finite resolution of Doppler spectra. We thereby show the importance for vertical incident sounders of rejecting echoes with large off-vertical angles, and the choice of appropriate signal-processing parameters for the accurate estimation of ionospheric motions. As an example, we consider the situation for vertical incident ionosondes and show that a low SNR can produce spurious echoes at relatively large zenith angles, which can, however, be avoided or minimized by the suitable choice of operating parameters.

  4. Fine-scale Structure of the Quasar 3C 279 Measured with 1.3 mm Very Long Baseline Interferometry

    NASA Astrophysics Data System (ADS)

    Lu, Ru-Sen; Fish, Vincent L.; Akiyama, Kazunori; Doeleman, Sheperd S.; Algaba, Juan C.; Bower, Geoffrey C.; Brinkerink, Christiaan; Chamberlin, Richard; Crew, Geoffrey; Cappallo, Roger J.; Dexter, Matt; Freund, Robert; Friberg, Per; Gurwell, Mark A.; Ho, Paul T. P.; Honma, Mareki; Inoue, Makoto; Jorstad, Svetlana G.; Krichbaum, Thomas P.; Loinard, Laurent; MacMahon, David; Marrone, Daniel P.; Marscher, Alan P.; Moran, James M.; Plambeck, Richard; Pradel, Nicolas; Primiani, Rurik; Tilanus, Remo P. J.; Titus, Michael; Weintroub, Jonathan; Wright, Melvyn; Young, Ken H.; Ziurys, Lucy M.

    2013-07-01

    We report results from five day very long baseline interferometry observations of the well-known quasar 3C 279 at 1.3 mm (230 GHz) in 2011. The measured nonzero closure phases on triangles including stations in Arizona, California, and Hawaii indicate that the source structure is spatially resolved. We find an unusual inner jet direction at scales of ~1 pc extending along the northwest-southeast direction (P.A. = 127° ± 3°), as opposed to other (previously) reported measurements on scales of a few parsecs showing inner jet direction extending to the southwest. The 1.3 mm structure corresponds closely with that observed in the central region of quasi-simultaneous super-resolution Very Long Baseline Array images at 7 mm. The closure phase changed significantly on the last day when compared with the rest of observations, indicating that the inner jet structure may be variable on daily timescales. The observed new direction of the inner jet shows inconsistency with the prediction of a class of jet precession models. Our observations indicate a brightness temperature of ~8 × 1010 K in the 1.3 mm core, much lower than that at centimeter wavelengths. Observations with better uv coverage and sensitivity in the coming years will allow the discrimination between different structure models and will provide direct images of the inner regions of the jet with 20-30 μas (5-7 light months) resolution.

  5. Development of a high accurate gear measuring machine based on laser interferometry

    NASA Astrophysics Data System (ADS)

    Lin, Hu; Xue, Zi; Yang, Guoliang; Huang, Yao; Wang, Heyan

    2015-02-01

    Gear measuring machine is a specialized device for gear profile, helix or pitch measurement. The classic method for gear measurement and the conventional gear measuring machine are introduced. In this gear measuring machine, the Abbe errors arisen from the angle error of guideways hold a great weight in affection of profile measurement error. For minimize of the Abbe error, a laser measuring system is applied to develop a high accurate gear measuring machine. In this laser measuring system, two cube-corner reflectors are placed close to the tip of probe, a laser beam from laser head is splited along two paths, one is arranged tangent to the base circle of gear for the measurement of profile and pitch, another is arranged parallel to the gear axis for the measurement of helix, both laser measurement performed with a resolution of 0.3nm. This approach not only improves the accuracy of length measurement but minimize the Abbe offset directly. The configuration of this improved measuring machine is illustrated in detail. The measurements are performed automatically, and all the measurement signals from guide rails, rotary table, probe and laser measuring system are obtained synchronously. Software collects all the data for further calculation and evaluation. The first measurements for a gear involute artifact and a helix artifact are carried out, the results are shown and analyzed as well.

  6. Stitching interferometry: side effects and PSD

    NASA Astrophysics Data System (ADS)

    Bray, Michael

    1999-11-01

    Stitching Interferometry is rapidly emerging as an alternative to Standard Interferometry, in the measurement of Large Optics -- such as those found in Laser MegaJoule and NIF. Stitching Interferometry involves multiple overlapping sub-aperture measurements over large components, and a computer software to reconstruct the wavefronts. Obviously, the Stitching Interferometer's measurement characteristics have to be different to those of the Standard Interferometer of same nominal measurement area. Two questions emerge: (1) What metric do we choose to express these characteristics? (2) How does Stitching Interferometry compare to Standard Interferometry, using this metric? We choose to use the PSD to illustrate how Stitching Interferometry of large components compares with Standard Large-Size Interferometry, for various lateral scales. Also, we highlight some important characteristics of Stitching Interferometry, which arise from judicious use of the particular configuration of the device. Ignorance of basic propagation phenomena can lead to bad design of the Stitching Interferometer, and loss of any performance advantage over Standard Interferometry. Because many of these effects are not direct consequences of the Stitching process, we call them side effects. In this paper, we provide basic explanation, and keep the mathematics to a low profile -- indeed, it is not necessary to actually compute anything to understand the effects. However, some very basic formulas, a few numerical tables and lots of graphs are presented, in order to provide basis for discussion.

  7. Interferometry system for out-of-plane microdisplacement measurement: application to mechanical expertise of scratch drive actuators

    NASA Astrophysics Data System (ADS)

    Jozwik, Michal; Gorecki, Christophe; Le Moal, Patrice; Joseph, Eric; Minotti, Patrice

    2003-10-01

    The material properties of silicon, as well as the planar and monolithic nature of the microstructures make electrostatic field energy conversion the most suitable driving principle on the micrometer scale. Moreover, compared with most other actuation principles, the scaling of electrostatic forces is particularly suitable for actuator downsizing. In spite of the advantages, it is still difficult to obtain appropriate driving characteristics because of silicon based actuator limitations such as small structural height, micrometer gap requirements and material limitations in the shaping process. Actuators require specific tools to verify that their mechanical properties and motions obey the designer's intent. In this paper capabilities of future direct-drive electrostatic actuators SDA (Scratch Drive Actuators) are investigated through the characterisation of their out-of-plane displacements by interferometry. The actuation involves contact interactions by using flexible polysilicon elementary actuator plate. The region of the physical contact is measured using Twyman-Green interferometer incorporated within a metallurgical microscope. The shapes and out-of-plane displacements of microstructures are extracted from interferograms by temporal phase shift method (TPS). Additionally, the results from interferometric method are compared with numerical simulations given by finite elements software - ANSYS.

  8. Deflectometry vs. interferometry

    NASA Astrophysics Data System (ADS)

    Häusler, Gerd; Faber, Christian; Olesch, Evelyn; Ettl, Svenja

    2013-04-01

    Quantitative deflectometry is a new tool to measure specular surfaces. The spectrum of measurable surfaces ranges from flat to freeform surfaces with steep slopes, with a size ranging from millimeters to several meters. We illustrate this by several applications: eye glass measurements, measurements of big mirrors, and in-line measurements in ultra-precision manufacturing without unclamping of the sample. We describe important properties of deflectometry and compare its potentials and limitations with interferometry. We discuss which method is superior for which application and how the potential of deflectometry may be developing in the future.

  9. Seismic interferometry for temporal monitoring

    NASA Astrophysics Data System (ADS)

    Nakata, Norimitsu

    Seismic interferometry, where one computes coherency of waves between two or more receivers and averages over many sources, is a technique of signal processing to reconstruct wavefields. This technique is used in geophysics, especially exploration geophysics and seismology. After more than a half century from the first study related to seismic interferometry (although the name of seismic interferometry has been used for approximately the last 15 years), researchers have developed this technique for many aspects: using multiples for increasing illuminations, enhancement of survey areas, ambient-noise analysis, and removal of the imprint of a complicated overburden. In this dissertation, I focus on the advantages of seismic interferometry for time-lapse measurements. Measurements of temporal changes yield beneficial information of fluid flow, crustal deformation, temperature, and/or stress. Estimation of temporal changes using active sources is, however, technically and economically challenging. Because seismic interferometry reconstruct waves that would have been recorded with a repeatable active sources using only receivers, this technique is appropriate for temporal monitoring. With seismic interferometry, one obtains some advantages that include canceling the complexity of wave propagation to a virtual source, creating virtual shear-wave (S-wave) sources (active S sources are expensive), and using waves that are not usable for active sources (e.g., ambient noise and multiples). I seek applications of seismic interferometry in a variety of topics (i.e., seismology, structural engineering, and exploration geophysics), and develop and/or modify several techniques of seismic interferometry for each application. Some chapters focus on developing techniques of seismic interferometry, and other chapters aim to estimate and interpret temporal changes with the developed techniques. For passive seismic sources, deconvolution-based seismic interferometry has better

  10. Measurement of strain distribution in cortical bone around miniscrew implants used for orthodontic anchorage using digital speckle pattern interferometry

    NASA Astrophysics Data System (ADS)

    Kumar, Manoj; Agarwal, Rupali; Bhutani, Ravi; Shakher, Chandra

    2016-05-01

    An application of digital speckle pattern interferometry (DSPI) for the measurement of deformations and strain-field distributions developed in cortical bone around orthodontic miniscrew implants inserted into the human maxilla is presented. The purpose of this study is to measure and compare the strain distribution in cortical bone/miniscrew interface of human maxilla around miniscrew implants of different diameters, different implant lengths, and implants of different commercially available companies. The technique is also used to measure tilt/rotation of canine caused due to the application of retraction springs. The proposed technique has high sensitivity and enables the observation of deformation/strain distribution. In DSPI, two specklegrams are recorded corresponding to pre- and postloading of the retraction spring. The DSPI fringe pattern is observed by subtracting these two specklegrams. Optical phase was extracted using Riesz transform and the monogenic signal from a single DSPI fringe pattern. The obtained phase is used to calculate the parameters of interest such as displacement/deformation and strain/stress. The experiment was conducted on a dry human skull fulfilling the criteria of intact dental arches and all teeth present. Eight different miniscrew implants were loaded with an insertion angulation of 45 deg in the inter-radicular region of the maxillary second premolar and molar region. The loading of miniscrew implants was done with force level (150 gf) by nickel-titanium closed-coil springs (9 mm). The obtained results from DSPI reveal that implant diameter and implant length affect the displacement and strain distribution in cortical bone layer surrounding the miniscrew implant.

  11. Experimental Evaluation of White Light Fabry-Perot Interferometry Fiber-Optic Strain Gages when Measuring Small Strains

    NASA Technical Reports Server (NTRS)

    St.Cyr, William; Figueroa, Fernando; VanDyke, David; McVay, Greg; Mitchell, Mark

    2002-01-01

    An experimental study was conducted to evaluate whether fiber optic strain gages (FOSG) are "better" sensors than typical foil gages. A particularly attractive feature of FOSG was their specified resolution of 0.01% of full-scale (0.1 micro strain for 1000 micro strain full-scale). This feature would make FOSG practical tank level sensors, by measuring very small strains on the support structure of a tank. A specific application in mind was to measure liquid oxygen tank level, with support beams that were predicted to contract approximately 11 micro strain as the tank goes from empty to full. Among various fiber optic technologies currently available, Fabry-Perot Interferometry using white light was selected. This technology exhibits highly desirable feature such as absolute strain measurement, linearity over its full-scale, and temperature compensation. However, experiment results suggest that the resolution is 0.8 micro strain, at best, calibration from one sensor to another can be off by 2.4 - 11.2%, and that temperature compensation is not fully predictable, with errors of up to 3.5 micro strain over an 11C range. Hence, when compared with classic foil gages, FOSG possess less accuracy, similar resolution and repeatability (precision), and superior linearity over their entire operating range. They are immune to EMI and their signals suffer minimal degradation over long distances. It is also expected that drift with time will be minimal in FOSG whereas the gage factor of foil sensors changes over time when exposed to varying environmental conditions. In conclusion, FOSG are "better" than foil gages as long as the application allows calibration of individual units as installed for operation.

  12. Analyzing spatial correlations in tissue using angle-resolved low coherence interferometry measurements guided by co-located optical coherence tomography.

    PubMed

    Kim, Sanghoon; Heflin, Stephanie; Kresty, Laura A; Halling, Meredith; Perez, Laura N; Ho, Derek; Crose, Michael; Brown, William; Farsiu, Sina; Arshavsky, Vadim; Wax, Adam

    2016-04-01

    Angle-resolved low coherence interferometry (a/LCI) is an optical technique used to measure nuclear morphology in situ. However, a/LCI is not an imaging modality and can produce ambiguous results when the measurements are not properly oriented to the tissue architecture. Here we present a 2D a/LCI system which incorporates optical coherence tomography imaging to guide the measurements. System design and characterization are presented, along with example cases which demonstrate the utility of the combined measurements. In addition, future development and applications of this dual modality approach are discussed. PMID:27446664

  13. Analyzing spatial correlations in tissue using angle-resolved low coherence interferometry measurements guided by co-located optical coherence tomography

    PubMed Central

    Kim, Sanghoon; Heflin, Stephanie; Kresty, Laura A.; Halling, Meredith; Perez, Laura N.; Ho, Derek; Crose, Michael; Brown, William; Farsiu, Sina; Arshavsky, Vadim; Wax, Adam

    2016-01-01

    Angle-resolved low coherence interferometry (a/LCI) is an optical technique used to measure nuclear morphology in situ. However, a/LCI is not an imaging modality and can produce ambiguous results when the measurements are not properly oriented to the tissue architecture. Here we present a 2D a/LCI system which incorporates optical coherence tomography imaging to guide the measurements. System design and characterization are presented, along with example cases which demonstrate the utility of the combined measurements. In addition, future development and applications of this dual modality approach are discussed. PMID:27446664

  14. Multiple wavelength interferometry for distance measurements of moving objects with nanometer uncertainty

    NASA Astrophysics Data System (ADS)

    Kuschmierz, R.; Czarske, J.; Fischer, A.

    2014-08-01

    Optical measurement techniques offer great opportunities in diverse applications, such as lathe monitoring and microfluidics. Doppler-based interferometric techniques enable simultaneous measurement of the lateral velocity and axial distance of a moving object. However, there is a complementarity between the unambiguous axial measurement range and the uncertainty of the distance. Therefore, we present an extended sensor setup, which provides an unambiguous axial measurement range of 1 mm while achieving uncertainties below 100 nm. Measurements at a calibration system are performed. When using a pinhole for emulating a single scattering particle, the tumbling motion of the rotating object is resolved with a distance uncertainty of 50 nm. For measurements at the rough surface, the distance uncertainty amounts to 280 nm due to a lower signal-to-noise ratio. Both experimental results are close to the respective Cramér-Rao bound, which is derived analytically for both surface and single particle measurements.

  15. Measurements of the Ground-State Polarizabilities of Cs, Rb, and K using Atom Interferometry

    NASA Astrophysics Data System (ADS)

    Gregoire, Maxwell; Hromada, Ivan; Holmgren, William; Trubko, Raisa; Cronin, Alex

    2016-05-01

    We measured the ground-state static electric-dipole polarizabilities of Cs, Rb, and K atoms with 0.2% uncertainty using a three-nanograting Mach-Zehnder atom beam interferometer. Since thermal Cs atoms have short de Broglie wavelengths, we developed measurement methods that do not require resolved atom diffraction: we used phase choppers to measure atomic beam velocity distributions, and electric field gradients to induce polarizability-dependent phase shifts. Our measurements provide benchmark tests for atomic structure calculations and thus test the underlying theory used to interpret atomic parity non-conservation experiments.

  16. Development of an integrated endoscopic device for multiplexed low coherence interferometry measurements of microbicide gel coating thickness

    NASA Astrophysics Data System (ADS)

    Drake, Tyler K.; Robles, Francisco E.; DeSoto, Michael; Henderson, Marcus H.; Katz, David F.; Wax, Adam P.

    2009-02-01

    Microbicide gels are topical products that have recently been developed to combat sexually transmitted diseases including HIV/AIDS. The extent of gel coverage, thickness, and structure are crucial factors in gel effectiveness. It is necessary to be able to monitor gel distribution and behavior under various circumstances, such as coatis, and over an extended time scale in vivo. We have developed a multiplexed, Fourier-domain low coherence interferometry (LCI) system as a practical method of measuring microbicide gel distribution, with precision and accuracy comparable to currently used fluorometric techniques techniques. The multiplexed system achieved a broad scanning area without the need for a mechanical scanning device, typical of OCT systems, by utilizing six parallel channels with simultaneous data collection. We now propose an imaging module which will allow the integration of the multiplexed LCI system into the current fluorescence system in conjunction with an endoscope. The LCI imaging module will meet several key criteria in order to be compatible with the current system. The fluorescent system features a 4-mm diameter rigid endsoscope enclosed in a 27-mm diameter polycarbonate tube, with a water immersion tip. Therefore, the LCI module must be low-profile as well as water-resistant to fit inside the current design. It also must fulfill its primary function of delivering light from each of the six channels to the gel and collecting backscattered light. The performance of the imaging module will be characterized by scanning a calibration socket which contains grooves of known depths, and comparing these measurements to the fluorometric results.

  17. Measurement of energy contrast of amplified ultrashort pulses using cross-polarized wave generation and spectral interferometry.

    PubMed

    Iliev, Marin; Meier, Amanda K; Galloway, Benjamin; Adams, Daniel E; Squier, Jeff A; Durfee, Charles G

    2014-07-28

    We present a method using spectral interferometry (SI) to characterize a pulse in the presence of an incoherent background such as amplified spontaneous emission (ASE). The output of a regenerative amplifier is interfered with a copy of the pulse that has been converted using third-order cross-polarized wave generation (XPW). The ASE shows as a pedestal background in the interference pattern. The energy contrast between the short-pulse component and the ASE is retrieved. The spectra of the interacting beams are obtained through an improvement to the self-referenced spectral interferometry (SRSI) analysis. PMID:25089416

  18. Measurements of the ground-state polarizabilities of Cs, Rb, and K using atom interferometry

    NASA Astrophysics Data System (ADS)

    Gregoire, Maxwell D.; Hromada, Ivan; Holmgren, William F.; Trubko, Raisa; Cronin, Alexander D.

    2015-11-01

    We measured the ground-state static electric-dipole polarizabilities of Cs, Rb, and K atoms using a three-nanograting Mach-Zehnder atom beam interferometer. Our measurements provide benchmark tests for atomic structure calculations and thus test the underlying theory used to interpret atomic parity-nonconservation experiments. We measured αCs=4 π ɛ0×59.39 (9 ) Å3,αRb=4 π ɛ0×47.39 (8 ) Å3 , and αK=4 π ɛ0×42.93 (7 ) Å3 . In atomic units, these measurements are αCs=401.2 (7 ) ,αRb=320.1 (6 ) , and αK=290.0 (5 ) . We report ratios of polarizabilities αCs/αRb=1.2532 (10 ) ,αCs/αK=1.3834 (9 ) , and αRb/αK=1.1040 (9 ) with smaller fractional uncertainty because the systematic errors for individual measurements are largely correlated. Since Cs atom beams have short de Broglie wavelengths, we developed measurement methods that do not require resolved atom diffraction. Specifically, we used phase choppers to measure atomic beam velocity distributions, and we used electric field gradients to give the atom interference pattern a phase shift that depends on atomic polarizability.

  19. Nanoscale fluctuations and surface tension measurements in droplets using phase-resolved low-coherence interferometry.

    PubMed

    Wang, Ru; Kim, Taewoo; Mir, Mustafa; Popescu, Gabriel

    2013-01-01

    A common-path interferometer was designed with rapidly tunable broadband swept laser source, which provides quantitative phase measurements of nanometer scale motions with very high sensitivity. With this setup, we are able to detect the thermal fluctuations in liquid droplets hanging at the end of an optical fiber. The measured nanoscale displacement fluctuations of various droplet surfaces were used to extract the surface tension. This newly developed technique proved the feasibility of noninvasive, fast, phase-resolved dynamic light scattering measurement of fluid mechanical properties. PMID:23292390

  20. Measurement of optical thickness variation of BK7 plate by wavelength tuning interferometry.

    PubMed

    Kim, Yangjin; Hibino, Kenichi; Sugita, Naohiko; Mitsuishi, Mamoru

    2015-08-24

    This paper presents the derivation of a 17-sample phase-shifting algorithm that can compensate the miscalibration and first-order nonlinearity of phase shift error, coupling error, and bias modulation of the intensity and satisfy the fringe contrast maximum condition. The phase error of measurements performed using the 17-sample algorithm is discussed and compared with those of measurements obtained using other algorithms. Finally, the optical thickness variation of a BK7 optically transparent plate obtained using a wavelength tuning Fizeau interferometer and the 17-sample algorithm are presented. The experimental results indicate that the optical thickness variation measurement accuracy for the BK7 plate was 3 nm. PMID:26368260

  1. Technique for the focal-length measurement of positive lenses using Fizeau interferometry

    SciTech Connect

    Pavan Kumar, Yeddanapudi; Chatterjee, Sanjib

    2009-02-01

    We present what we believe is a new technique for the focal-length measurement of positive lenses using Fizeau interferometery. The technique utilizes the Gaussian lens equation. The image distance is measured interferometrically in terms of the radius of curvature of the image-forming wavefront emerging from the lens. The radii of curvature of the image-forming wavefronts corresponding to two different axial object positions of known separation are measured. The focal length of the lens is determined by solving the equations obtained using the Gaussian lens equation for the two object positions. Results obtained for a corrected doublet lens of a nominal focal length of 200.0 mm with a measurement uncertainty of {+-}2.5% is presented.

  2. Radius of Curvature Measurement of Large Optics Using Interferometry and Laser Tracker

    NASA Technical Reports Server (NTRS)

    Hagopian, John; Connelly, Joseph

    2011-01-01

    The determination of radius of curvature (ROC) of optics typically uses either a phase measuring interferometer on an adjustable stage to determine the position of the ROC and the optics surface under test. Alternatively, a spherometer or a profilometer are used for this measurement. The difficulty of this approach is that for large optics, translation of the interferometer or optic under test is problematic because of the distance of translation required and the mass of the optic. Profilometry and spherometry are alternative techniques that can work, but require a profilometer or a measurement of subapertures of the optic. The proposed approach allows a measurement of the optic figure simultaneous with the full aperture radius of curvature.

  3. Remarks on Residual Stress Measurement by Hole-Drilling and Electronic Speckle Pattern Interferometry

    PubMed Central

    2014-01-01

    Hole drilling is the most widespread method for measuring residual stress. It is based on the principle that drilling a hole in the material causes a local stress relaxation; the initial residual stress can be calculated by measuring strain in correspondence with each drill depth. Recently optical techniques were introduced to measure strain; in this case, the accuracy of the final results depends, among other factors, on the proper choice of the area of analysis. Deformations are in fact analyzed within an annulus determined by two parameters: the internal and the external radius. In this paper, the influence of the choice of the area of analysis was analysed. A known stress field was introduced on a Ti grade 5 sample and then the stress was measured in correspondence with different values of the internal and the external radius of analysis; results were finally compared with the expected theoretical value. PMID:25276850

  4. Analysis and testing of a new method for drop size measurement using laser scatter interferometry

    NASA Technical Reports Server (NTRS)

    Bachalo, W. D.; Houser, M. J.

    1984-01-01

    Research was conducted on a laser light scatter detection method for measuring the size and velocity of spherical particles. The method is based upon the measurement of the interference fringe pattern produced by spheres passing through the intersection of two laser beams. A theoretical analysis of the method was carried out using the geometrical optics theory. Experimental verification of the theory was obtained by using monodisperse droplet streams. Several optical configurations were tested to identify all of the parametric effects upon the size measurements. Both off-axis forward and backscatter light detection were utilized. Simulated spray environments and fuel spray nozzles were used in the evaluation of the method. The measurements of the monodisperse drops showed complete agreement with the theoretical predictions. The method was demonstrated to be independent of the beam intensity and extinction resulting from the surrounding drops. Signal processing concepts were considered and a method was selected for development.

  5. Laser interferometry method for absolute measurement of the acceleration of gravity

    NASA Technical Reports Server (NTRS)

    Hudson, O. K.

    1971-01-01

    Gravimeter permits more accurate and precise absolute measurement of g without reference to Potsdam values as absolute standards. Device is basically Michelson laser beam interferometer in which one arm is mass fitted with corner cube reflector.

  6. Interferometry based technique for intensity profile measurements of far IR beams.

    PubMed

    Soloviev, Alexander A; Khazanov, Efim A; Kozhevatov, Ilya E; Palashov, Oleg V

    2007-06-20

    We present a novel, to the best of our knowledge, method for measuring the intensity profile of far-IR beams. The method is based on the measurements of nonstationary variation in optical thickness of a fused-silica plate heated by the studied radiation. The optical thickness is observed by means of a reflecting interferometer. Purpose-made experimental setup allows one to measure beams with an aperture of up to 60 mm with a spatial resolution of 1 mm. The accessibility of the utilized technologies and the possibility to easily increase the aperture are the major advantages of this approach. The probable area of application for the method is measurements of beams produced by powerful industrial far-IR lasers. PMID:17538679

  7. Far-infrared polarimetry/interferometry for poloidal magnetic field measurement on ZT-40M

    SciTech Connect

    Erickson, R.M.

    1986-06-01

    The measurement of internal magnetic field profiles may be a very important step in the understanding of magnetic confinement physics issues. The measurement of plasma-induced Faraday rotation is one of the more promising internal magnetic field diagnostics. This thesis describes the development of a heterodyne polarimeter/interferometer for internal poloidal magnetic field measurement on ZT-40M. Heterodyne techniques were employed because of the insensitivity to spurious signal amplitude changes that cause errors in other methods. Initial problems in polarimetric sensitivity were observed that were ultimately found to be related to discharge-induced motions of the constrained diagnostic access on ZT-40M. Grazing incidence motions of the constrained diagnostic access on ZT-40M. Grazing incidence reflections on metallic surfaces of the diagnostic ports caused polarization changes that affected the measurement accuracy. Installation of internally threaded sleeves to baffle the reflections eliminated the sensitivity problem, and allowed useful Faraday rotation measurements to be made. Simultaneous polarimetric and interferometric measurements have also been demonstrated. The ability to assemble a working heterodyne polarimeter/interferometer is no longer in question. The extension of the present system to multichord operation requires increased laser power and efficiency.

  8. Measurement Variability of Vertical Scanning Interferometry Tool Used for Orbiter Window Defect Assessment

    NASA Technical Reports Server (NTRS)

    Padula, Santo, II

    2009-01-01

    The ability to sufficiently measure orbiter window defects to allow for window recertification has been an ongoing challenge for the orbiter vehicle program. The recent Columbia accident has forced even tighter constraints on the criteria that must be met in order to recertify windows for flight. As a result, new techniques are being investigated to improve the reliability, accuracy and resolution of the defect detection process. The methodology devised in this work, which is based on the utilization of a vertical scanning interferometric (VSI) tool, shows great promise for meeting the ever increasing requirements for defect detection. This methodology has the potential of a 10-100 fold greater resolution of the true defect depth than can be obtained from the currently employed micrometer based methodology. An added benefit is that it also produces a digital elevation map of the defect, thereby providing information about the defect morphology which can be utilized to ascertain the type of debris that induced the damage. However, in order to successfully implement such a tool, a greater understanding of the resolution capability and measurement repeatability must be obtained. This work focused on assessing the variability of the VSI-based measurement methodology and revealed that the VSI measurement tool was more repeatable and more precise than the current micrometer based approach, even in situations where operator variation could affect the measurement. The analysis also showed that the VSI technique was relatively insensitive to the hardware and software settings employed, making the technique extremely robust and desirable

  9. Measurement of spatiotemporal phase statistics in turbulent air flow using high-speed digital holographic interferometry.

    PubMed

    Lycksam, Henrik; Sjödahl, Mikael; Gren, Per

    2010-03-10

    We describe a method of measuring spatiotemporal (ST) structure and covariance functions of the phase fluctuations in a collimated light beam propagated through a region of refractive index turbulence. The measurements are performed in a small wind tunnel, in which a turbulent temperature field is created using heated wires at the inlet of the test section. A collimated sheet of light is sent through the channel, and the phase fluctuations across the sheet are measured. The spatial phase structure function can be estimated from a series of images captured at an arbitrary frame rate by spatial phase unwrapping, whereas the ST structure function requires a time resolved measurement and a full three-dimensional unwrapping. The measured spatial phase structure function shows agreement with the Kolmogorov theory with a pronounced inertial subrange, which is taken as a validation of the method. Because of turbulent mixing in the boundary layers close to the walls of the channel, the flow will not obey the Taylor hypothesis of frozen turbulence. This can be clearly seen in the ST structure function calculated in a coordinate system that moves along with the bulk flow. At zero spatial separation, this function should always be zero according to the Taylor hypothesis, but due to the mixing effect there will be a growth in the structure function with increasing time difference depending on the rate of mixing. PMID:20220886

  10. Rabi interferometry and sensitive measurement of the Casimir-Polder force with ultracold gases

    SciTech Connect

    Chwedenczuk, Jan; Piazza, Francesco; Smerzi, Augusto; Pezze, Luca

    2010-09-15

    We show that Rabi oscillations of a degenerate fermionic or bosonic gas trapped in a double-well potential can be exploited for the interferometric measurement of external forces at micrometer length scales. The Rabi interferometer is less sensitive but easier to implement than the Mach-Zehnder, since it does not require dynamical beam-splitting or recombination processes. As an application we propose a measurement of the Casimir-Polder force acting between the atoms and a dielectric surface. We find that even if the interferometer is fed with a coherent state of relatively small number of atoms, and in the presence of realistic experimental noise, the force might be measured with a sensitivity sufficient to discriminate between thermal and zero-temperature regimes of the Casimir-Polder potential. Higher sensitivities can be reached with bosonic spin squeezed states.

  11. Phase-sensitive measurements of order parameters for ultracold atoms through two-particle interferometry.

    PubMed

    Kitagawa, Takuya; Aspect, Alain; Greiner, Markus; Demler, Eugene

    2011-03-18

    Nontrivial symmetry of order parameters is crucial in some of the most interesting quantum many-body states of ultracold atoms as well as condensed matter systems. Examples in cold atoms include p-wave Feshbach molecules and d-wave paired states of fermions that could be realized in optical lattices in the Hubbard regime. Identifying these states in experiments requires measurements of the relative phase of different components of the entangled pair wave function. We propose and discuss two schemes for such phase-sensitive measurements, based on two-particle interference revealed in atom-atom or atomic density correlations. Our schemes can also be used for relative phase measurements for nontrivial particle-hole order parameters, such as d-density wave order. PMID:21469872

  12. Skin friction measurements by laser interferometry in swept shock wave/turbulent boundary-layer interactions

    NASA Technical Reports Server (NTRS)

    Kim, Kwang-Soo; Settles, Gary S.

    1988-01-01

    The laser interferometric skin friction meter was used to measure wall shear stress distributions in two interactions of fin-generated swept shock waves with turbulent boundary layers. The basic research configuration was an unswept sharp-leading-edge fin of variable angle mounted on a flatplate. The results indicate that such measurements are practical in high-speed interacting flows, and that a repeatability of + or - 6 percent or better is possible. Marked increases in wall shear were observed in both swept interactions tested.

  13. Temperature field measurement of an array of laminar premixed slot flame Jets using Mach-Zehnder interferometry

    NASA Astrophysics Data System (ADS)

    Najafian Ashrafi, Z.; Ashjaee, M.

    2015-05-01

    An experimental study was performed to investigate the influence of Reynolds number (Re) and non-dimensional jet-to-jet spacing (S/Dh) on flame shape, structure and temperature field of an array of laminar premixed slot flame jets. Mach-Zehnder interferometry technique is used to obtain an insight to the overall temperature field between single, twin and triple slot flame jets. The slot jets with large aspect ratio (L/W), length of L=60 mm and width of W=6 mm were used to eliminate the three-dimensional effect of temperature field. The effect of jet-to-jet spacing was investigated on flame characteristics under the test conditions of 200≤Re≤400 and equivalence ratio (φ) of unity. The present measurement reveals that the variation of maximum flame temperature with increment of Reynolds number is mainly due to heat transfer effects and is negligible while the flame height is increased. For the cases of twin and triple flame jets by increasing Reynolds number and decreasing non-dimensional jet-to-jet spacing (S/Dh), the interferences between the jets are increased and the jets attracted each other. Strong interference was observed at S/Dh=1.15. For the case of triple jets at this S/Dh, the central jet was suppressed while the side jets deflected towards the inner jet. The interference between jets was found to reduce the heat flux in the jet-to-jet interacting zone due to incomplete combustion. Also the optimum jet-to-jet spacing of triple flame jets is obtained at each Reynolds number to enhance the heat transfer performance of the jets.

  14. Low-coherence interferometry based roughness measurement on turbine blade surfaces using wavelet analysis

    NASA Astrophysics Data System (ADS)

    Zou, Yibo; Li, Yinan; Kaestner, Markus; Reithmeier, Eduard

    2016-07-01

    In this paper, a non-contact optical system, a low-coherence interferometer (LCI), is introduced for the purpose of measuring the surface roughness of turbine blades. The designed system not only possesses a high vertical resolution and is able to acquire the roughness topography, but also it has a large vertical scanning range compared to other commonly used optical systems. The latter characteristic allows us to measure turbine blades surfaces with large curvature without collisions between the lens and the measurement object. After obtaining the surface topography, wavelet analysis is applied to decompose the original surface into multiple bandwidths to conduct a multiscale analysis. The results show that the developed LCI system proofs a good performance not only in obtaining the surface topography in the roughness scale but also in being able to measure surfaces of objects that possess a complex geometry in a large vertical range. Furthermore, the applied biorthogonal wavelet in this study has performed good amplitude and phase properties in extracting the roughness microstructures from the whole surface. Finally, the traditional roughness parameters, such as the mean surface roughness Sa and the Root Mean Square (RMS) roughness Sq, are evaluated in each decomposed subband and their correlations with the scale of each subband are analyzed.

  15. Simultaneous displacement and slope measurement in electronic speckle pattern interferometry using adjustable aperture multiplexing.

    PubMed

    Lu, Min; Wang, Shengjia; Aulbach, Laura; Koch, Alexander W

    2016-08-01

    This paper suggests the use of adjustable aperture multiplexing (AAM), a method which is able to introduce multiple tunable carrier frequencies into a three-beam electronic speckle pattern interferometer to measure the out-of-plane displacement and its first-order derivative simultaneously. In the optical arrangement, two single apertures are located in the object and reference light paths, respectively. In cooperation with two adjustable mirrors, virtual images of the single apertures construct three pairs of virtual double apertures with variable aperture opening sizes and aperture distances. By setting the aperture parameter properly, three tunable spatial carrier frequencies are produced within the speckle pattern and completely separate the information of three interferograms in the frequency domain. By applying the inverse Fourier transform to a selected spectrum, its corresponding phase difference distribution can thus be evaluated. Therefore, we can obtain the phase map due to the deformation as well as its slope of the test surface from two speckle patterns which are recorded at different loading events. By this means, simultaneous and dynamic measurements are realized. AAM has greatly simplified the measurement system, which contributes to improving the system stability and increasing the system flexibility and adaptability to various measurement requirements. This paper presents the AAM working principle, the phase retrieval using spatial carrier frequency, and preliminary experimental results. PMID:27505365

  16. 100-Picometer Interferometry for EUVL

    SciTech Connect

    Sommargren, G E; Phillion, D W; Johnson, M A; Nguyen, N O; Barty, A; Snell, F J; Dillon, D R; Bradsher, L S

    2002-03-18

    Future extreme ultraviolet lithography (EWL) steppers will, in all likelihood, have six-mirror projection cameras. To operate at the diffraction limit over an acceptable depth of focus each aspheric mirror will have to be fabricated with an absolute figure accuracy approaching 100 pm rms. We are currently developing visible light interferometry to meet this need based on modifications of our present phase shifting diffraction interferometry (PSDI) methodology where we achieved an absolute accuracy of 250pm. The basic PSDI approach has been further simplified, using lensless imaging based on computational diffractive back-propagation, to eliminate auxiliary optics that typically limit measurement accuracy. Small remaining error sources, related to geometric positioning, CCD camera pixel spacing and laser wavelength, have been modeled and measured. Using these results we have estimated the total system error for measuring off-axis aspheric EUVL mirrors with this new approach to interferometry.

  17. Optical interferometry at the Heisenberg limit with twin Fock states and parity measurements

    SciTech Connect

    Campos, R. A.; Gerry, Christopher C.; Benmoussa, A.

    2003-08-01

    Holland and Burnett [Phys. Rev. Lett. 71, 1355 (1993)] have argued that twin Fock states of equal photon number N injected at both input ports of a Mach-Zehnder interferometer lead to phase measurements with accuracies approaching the Heisenberg limit {delta}{phi}{sub HL}=1/(2N). However, the method of phase detection suggested by those authors, obtaining the difference of the photocurrents at the output ports of the interferometer, is not sensitive to the phase difference between the two interferometer paths; in fact, the photocurrent vanishes. In this paper we show that the use of parity measurements on just one of the output modes not only is sensitive to the phase difference but that the sensitivity approaches the Heisenberg limit for large N.

  18. Electron Density Measurements of a Field-Reversed Configuration Using Fiber Probe Interferometry

    NASA Astrophysics Data System (ADS)

    Camacho, J. F.; Lynn, A. G.; Ruden, E. L.

    2010-11-01

    A HeNe laser interferometer operating at 632.8 nm with two single-mode optical fiber probe beams has been assembled to measure time history of the line-integrated electron density of a field-reversed configuration (FRC) for a magnetized target fusion (MTF) experiment. Our system features probe path lengths many times longer than the reference paths. We have performed simultaneous measurements along two diameters at different axial locations. During plasma formation, translation, and capture tests, the lower probe monitored the formation region, while the upper probe monitored the capture region corresponding to the location of an imploding cylindrical aluminum liner driven by the Shiva Star capacitor bank to compress and heat the FRC plasma. For the actual imploding liner experiment, the upper chord was moved to monitor the translating FRC at the entrance to the liner region. Results from the formation, translation, and capture tests as well as an actual imploding liner experiment will be presented. In addition, interferometer visibility measurements and other factors establishing the viability of our design will be discussed.

  19. Laser Interferometry Measurements of Cold-Sprayed Copper Thermite Shocked to 30 GPa

    NASA Astrophysics Data System (ADS)

    Neel, Christopher; Lacina, David

    2015-06-01

    Plate impact experiments were conducted on a cold-sprayed Al-CuO thermite at peak stresses varying between 5-30 GPa to determine the Hugoniot and characterize any shock induced energetic reaction. Photon Doppler Velocimetry (PDV) measurements were used to obtain particle velocity histories and shock speed information for both the shock loading and unloading behavior of the material. Low stress experiments (<20GPa) exhibited a linearly increasing shock speed with increasing particle velocity. However, an obvious change in slope (i.e. a ``kink'') is present in the Hugoniot at stresses above ~ 20 GPa which follow a linear increase up to the highest stresses attained in this work. The change in Hugoniot curve suggests a volume-increasing reaction occurs in this shocked Al-CuO thermite near 20 GPa, but an analysis of the measured particle velocity histories does not support this assertion. To better characterize any shock-induced thermite reactions, emission spectroscopy measurements were obtained at stresses above and below 20 GPa.

  20. Measurements of the wavefront outer scale at Paranal: influence of this parameter in interferometry

    NASA Astrophysics Data System (ADS)

    Conan, Rodolphe; Ziad, Aziz; Borgnino, Julien; Martin, Francois; Tokovinin, Andrei A.

    2000-07-01

    The Generalized Seeing Monitor (GSM) has undertaken a campaign of measurement of the optical turbulent parameters: the Fried's parameter, the outer scale (L0) and the isoplanatic patch, at Paranal, the site of the VLT, in December 1998. The principle aim of this mission was to measure L0 values at Paranal. In a first part, we present the GSM, the results of the mission and particularly the statistics of L0. In a second part, we emphasize the effect of L0 on the optical path difference (OPD) values for the co-phasing of an interferometer. We derive the exact formulation of the OPD for the Von Karman model and we give the expected OPD at Paranal with L0 values measured by the GSM. We give also the expression of the residual OPD at the output of a fringe tracker system as a function of L0, of the exposure time of the fringe sensor and of the frequency of the closed-loop of the system.

  1. Temporal averaging of phase measurements in the presence of spurious phase drift - Application to phase-stepped real-time holographic interferometry

    NASA Technical Reports Server (NTRS)

    Ovryn, B.; Haacke, E. M.

    1993-01-01

    A technique that compensates for low spatial frequency spurious phase changes during an interference experiment is developed; it permits temporal averaging of multiple-phase measurements, made before and after object displacement. The method is tested with phase-stepped real-time holographic interferometry applied to cantilever bending of a piezoelectric bimorph ceramic. Results indicate that temporal averaging of the corrected data significantly reduces the white noise in a phase measurement without incurring systematic errors or sacrificing spatial resolution. White noise is reduced from 3 deg to less than 1 deg using these methods.

  2. Cooperative effects for measurement: Raman superradiance imaging and quantum states for Heisenberg limited interferometry

    NASA Astrophysics Data System (ADS)

    Uys, Hermann

    Cooperative effects in many-particle systems can be exploited to achieve measurement outcomes not possible with independent probe particles. We explore two measurement applications based on the cooperative phenomenon of superradiance or on correlated quantum states closely related to superradiance. In the first application we study the off-resonant superradiant Raman scattering of light from an ultracold Bose atomic vapor. We investigate the temperature dependence of superradiance for a trapped vapor and show that in the regime where superradiance occurs on a timescale comparable to a trap frequency, scattering takes place preferentially from atoms in the lowest trap levels due to Doppler dephasing. As a consequence, below the critical temperature for Bose condensation, absorption images of transmitted light serve as a direct probe of the condensed state. Subsequently, we consider a pure condensate and study the time-dependent spatial features of transmitted light, obtaining good qualitative agreement with recent imaging experiments. Inclusion of quantum fluctuations in the initial stages of the superradiant emission accounts well for shot-to-shot fluctuations. Secondly, we have used simulated annealing, a global optimization strategy, to systematically search for correlated quantum interferometer input states that approach the Heisenberg limited uncertainty in estimates of the interferometer phase shift. That limit improves over the standard quantum limit to the phase sensitivity of interferometric measurements by a factor of 1/ N , where N is the number of interfering particles. We compare the performance of these states to that of other non-classical states already known to yield Heisenberg limited uncertainty.

  3. SPECKLE INTERFEROMETRY AT SOAR IN 2010 AND 2011: MEASURES, ORBITS, AND RECTILINEAR FITS

    SciTech Connect

    Hartkopf, William I.; Mason, Brian D.; Tokovinin, Andrei E-mail: bdm@usno.navy.mil

    2012-02-15

    We report on the results of speckle observations at the 4.1 m SOAR telescope in 2010 and 2011. A total of 639 objects were observed. We give 562 measurements of 418 resolved binaries, including 21 pairs resolved for the first time, and upper detection limits for 221 unresolved stars. New orbital elements have been determined for 42 physical pairs, of which 22 are first-time calculations; the rest are corrections, sometimes substantial. Linear elements are calculated for nine apparently optical doubles. We comment on new pairs, new orbital solutions, and other remarkable objects.

  4. Invited Article: Expanded and improved traceability of vibration measurements by laser interferometry

    SciTech Connect

    Martens, Hans-Jürgen von

    2013-12-15

    Traceability to the International System of Units has been established for vibration and shock measurements as specified in international document standards, recommendations, and regulations to ensure product quality, health, and safety. New and upgraded laser methods and techniques developed by national metrology institutes and by leading manufacturers in the past two decades have been swiftly specified as standard methods in the ISO 16063 series of international document standards. In ISO 16063-11:1999, three interferometric methods are specified for the primary calibration of vibration transducers (reference standard accelerometers) in a frequency range from 1 Hz to 10 kHz. In order to specify the same (modified) methods for the calibration of laser vibrometers (ISO 16063-41:2011), their applicability in an expanded frequency range was investigated. Steady-state sinusoidal vibrations were generated by piezoelectric actuators at specific frequencies up to 347 kHz (acceleration amplitudes up to 376 km/s{sup 2}). The displacement amplitude, adjusted by the special interferometric method of coincidence to 158.2 nm (quarter the wavelength of the He-Ne laser light), was measured by the standardized interferometric methods of fringe counting and sine-approximation. The deviations between the measurement results of the three interferometric methods applied simultaneously were smaller than 1 %. The limits of measurement uncertainty specified in ISO 16063-11 between 1 Hz to 10 kHz were kept up to frequencies, which are orders of magnitude greater; the uncertainty limit 0.5 % specified at the reference frequency 160 Hz was not exceeded at 160 kHz. The reported results were considered during the development of ISO 16063-41 by specifying the instrumentation and procedures for performing calibrations of rectilinear laser vibrometers in the frequency range typically between 0.4 Hz and 50 kHz—the interferometric methods may be applied within expanded frequency ranges using

  5. Single-beam, dual-view digital holographic interferometry for biomechanical strain measurements of biological objects

    NASA Astrophysics Data System (ADS)

    Pantelić, Dejan V.; Grujić, Dušan Ž.; Vasiljević, Darko M.

    2014-12-01

    We describe a method for dual-view biomechanical strain measurements of highly asymmetrical biological objects, like teeth or bones. By using a spherical mirror, we were able to simultaneously record a digital hologram of the object itself and the mirror image of its (otherwise invisible) rear side. A single laser beam was sufficient to illuminate both sides of the object, and to provide a reference beam. As a result, the system was mechanically very stable, enabling long exposure times (up to 2 min) without the need for vibration isolation. The setup is simple to construct and adjust, and can be used to interferometrically observe any object that is smaller than the mirror diameter. Parallel data processing on a CUDA-enabled (compute unified device architecture) graphics card was used to reconstruct digital holograms and to further correct image distortion. We used the setup to measure the deformation of a tooth due to mastication forces. The finite-element method was used to compare experimental results and theoretical predictions.

  6. Frequency measurement of refraction index of air for high-resolution laser interferometry

    NASA Astrophysics Data System (ADS)

    Cip, Ondrej; Petru, Frantisek; Matousek, Vit; Lazar, Josef

    2004-08-01

    In the work, we present a method for direct measurement of the refraction index of air. We designed two coupled glass cells (one evacuated and the other filled by atmospheric air) inserted to plan-parallel Fabry-Perot resonator (F. P. resonator). Two tunable single-frequency lasers pass laser beams through the evacuated and aired cell simultaneously. Two F.-P. resonators are built up by this way: one of them in evacuated cell and the other in the open air cell. If both lasers are tuned along the resonant modes of F.-P. resonators, an optical frequency difference between two adjacent modes can be identified for each resonator. The evacuated one will have another mode-to-mode difference than the aired resonator. With knowledge of these values we can determine the index of refraction very fast. We verified the method with using Michelson interferometer based technique where a glass cell placed to the measurement arm of the interferometer is evacuated by an oil pump. In this case Michelson interferometer monitors changes of the optical path caused by the process of evacuation. Experimental results achieved by the method will be presented.

  7. Improved measurement of grain wall contact forces in granular beds using wavelength scanning interferometry

    NASA Astrophysics Data System (ADS)

    Zhou, Yanzhou; Wildman, Ricky D.; Huntley, Jonathan M.

    2005-06-01

    We describe a wholefield optical technique based on a wavelength scanning Fizeau interferometer for measuring the contact forces between a granular bed and a transparent substrate. The substrate material is polymethyl methacrylate (PMMA), aluminium-coated on the internal surface, and changes to the interference pattern formed by reflection from the two surfaces allow the displacement field induced by the contacting grains to be visualized. Quantitative displacement data are obtained by phase shifting the interference pattern using a tunable laser. In order to avoid miscalibration errors associated with the non-linearities of the laser source, a Newton-Raphson iteration scheme is employed to search for the correct PZT voltage required for the linear phase-shifting steps. A new 31-frame phase-shifting algorithm based on the Chebyshev window function was designed to deal with the problems of residual miscalibration and higher harmonics created by multiple reflections within the substrate. The resulting noise in the measurements is below 1 nm, and the repeatability of the load-displacement relationship was found to be approximately 10 nm.

  8. Measurement of grain wall contact forces in a granular bed using frequency-scanning interferometry

    NASA Astrophysics Data System (ADS)

    Osman, M. S.; Huntley, J. M.; Wildman, R. D.

    2005-07-01

    Micro-mechanical theories have recently been developed to model the propagation of force through a granular material based on single grain interactions. We describe here an experimental technique, developed to validate such theories, that is able to measure the individual contact forces between the grains and the wall of the containing vessel, thereby avoiding the spatial averaging effect of conventional pressure transducers. The method involves measuring interferometrically the deflection of an interface within a triple-layer elastic substrate consisting of epoxy, silicone rubber, and glass. A thin coating of gold between the epoxy and rubber acts as a reflective film, with the reference wave provided by the glass/air interface. Phase shifting is carried out by means of a tunable laser. Phase difference maps are calculated using a 15-frame phase-shifting formula based on a Hanning window. The resulting displacement resolution of order 1 nm allows the wall stiffness to be increased by some two orders of magnitude compared to previously described methods in the literature.

  9. Measuring land subsidence by PALSAR interferometry in Yanzhou coal mine area

    NASA Astrophysics Data System (ADS)

    Wang, Zhiyong; Zhang, Jinzhi; Liu, Guolin

    2010-08-01

    In this paper, we used PALSAR data to measure the land subsidence in Yanzhou coal mining area based on InSAR technique. Firstly it simply analyzed InSAR technique and introduced some orbital radar satellites for InSAR measuring. It introduced the PALSAR data for test and the selection of InSAR pairs. Then it illustrated the procedure of 2-pass DInSAR data processing taking true data for example. It can be divided into inteferometric processing, simulating the interferogram according to DEM, differential processing and filtering, phase unwrapping, conversion of deformation. Then it got the deformation map of coal mining subsidence. It interpreted and analyzed the D-InSAR results in details. It generated the isoline maps of land subsidence in coal mining area. We found that the maximum land subsidences in vertical direction in two areas are up to 51.8 and 71.4 cm in 46 days. The test proves that PALSAR and SRTM DEM data are suitable for monitoring the land subsidence in areas with vegetated land cover, such as coal mining area.

  10. Atom Interferometry on Sounding Rockets

    NASA Astrophysics Data System (ADS)

    Seidel, S. T.; Lachmann, M. D.; Becker, D.; Grosse, J.; Popp, M. A.; Wang, J. B.; Wendrich, T.; Rasel, E. M.; Quantus Collaboration

    2015-09-01

    Atom interferometry in microgravity offers the possibility to perform high precision measurements of inertial forces complementary to experiments based on classical test masses. The ultimate goal is to perform these quantum measurements in space on board dedicated satellite missions. To reach this, a series of pathfinder microgravity experiments with cold atoms were build. The latest installment of these are conducted on sounding rockets. Here we give a short motivation of atom interferometry in space, an overview of the techniques used, and an introduction of the current mission MAIUS- 1.

  11. Range difference multilateration for obtaining precision geodetic and trajectory measurements. [by radio interferometry

    NASA Technical Reports Server (NTRS)

    Escobal, P. R.; Ong, K. M.; Von Roos, O. H.

    1975-01-01

    The theoretical aspects of a new multilateration technique suitable for precision geodesy and orbit determination applications are examined. The multilateration technique considered herein makes use of the differential time of arrival of signals at an ensemble of ground stations from a spacecraft or aircraft as the fundamental data type. It is demonstrated that simultaneous measurements give rise to a system of equations which upon solution permits the determination of the three-dimensional vehicle coordinates plus the three-dimensional coordinates of the station net relative to an arbitrarily adopted origin (which may be taken to be one of the stations). A solution to these equations can be obtained without any a priori knowledge of the locations of the stations and vehicle. The necessary conditions for obtaining all of these coordinates in the same solution are discussed, and it is indicated that at least five stations are required in the station ensemble.

  12. Reverse transduction measured in the living cochlea by low-coherence heterodyne interferometry.

    PubMed

    Ren, Tianying; He, Wenxuan; Barr-Gillespie, Peter G

    2016-01-01

    It is generally believed that the remarkable sensitivity and frequency selectivity of mammalian hearing depend on outer hair cell-generated force, which amplifies sound-induced vibrations inside the cochlea. This 'reverse transduction' force production has never been demonstrated experimentally, however, in the living ear. Here by directly measuring microstructure vibrations inside the cochlear partition using a custom-built interferometer, we demonstrate that electrical stimulation can evoke both fast broadband and slow sharply tuned responses of the reticular lamina, but only a slow tuned response of the basilar membrane. Our results indicate that outer hair cells can generate sufficient force to drive the reticular lamina over all audible frequencies in living cochleae. Contrary to expectations, the cellular force causes a travelling wave rather than an immediate local vibration of the basilar membrane; this travelling wave vibrates in phase with the reticular lamina at the best frequency, and results in maximal vibration at the apical ends of outer hair cells. PMID:26732830

  13. A Practical Theorem on Using Interferometry to Measure the Global 21-cm Signal

    NASA Astrophysics Data System (ADS)

    Venumadhav, Tejaswi; Chang, Tzu-Ching; Doré, Olivier; Hirata, Christopher M.

    2016-08-01

    The sky-averaged, or global, background of redshifted 21 cm radiation is expected to be a rich source of information on cosmological reheating and reionization. However, measuring the signal is technically challenging: one must extract a small, frequency-dependent signal from under much brighter spectrally smooth foregrounds. Traditional approaches to study the global signal have used single antennas, which require one to calibrate out the frequency-dependent structure in the overall system gain (due to internal reflections, for example) as well as remove the noise bias from auto-correlating a single amplifier output. This has motivated proposals to measure the signal using cross-correlations in interferometric setups, where additional calibration techniques are available. In this paper we focus on the general principles driving the sensitivity of the interferometric setups to the global signal. We prove that this sensitivity is directly related to two characteristics of the setup: the cross-talk between readout channels (i.e., the signal picked up at one antenna when the other one is driven) and the correlated noise due to thermal fluctuations of lossy elements (e.g., absorbers or the ground) radiating into both channels. Thus in an interferometric setup, one cannot suppress cross-talk and correlated thermal noise without reducing sensitivity to the global signal by the same factor—instead, the challenge is to characterize these effects and their frequency dependence. We illustrate our general theorem by explicit calculations within toy setups consisting of two short-dipole antennas in free space and above a perfectly reflecting ground surface, as well as two well-separated identical lossless antennas arranged to achieve zero cross-talk.

  14. Initial planning for interferometry measurements on triggered plasma opening switch source.

    SciTech Connect

    Lynn, Alan G.; Jackson, Daniel Peter Jr.; Savage, Mark Edward; Sharpe, Rob A.; Gilmore, Mark A.

    2005-06-01

    The Triggered Plasma Opening Switch (TPOS) at SNL is a unique device that exploits the high conductivity and low mass properties of plasma. The TPOS's objective is to take the initial {approx}0.8 MA ({approx}250 ns rise time) storage inductor current and deliver {approx}0.5 MA at {approx}2.4 MV ({approx}10 ns rise time) to a load of {approx}5-10 Omega. Configuration advantages include low current jitter and resistive voltage drop, power gain, and minimization of trigger input power as the result of using two stages in series. This two-stage design is novel and is the first to demonstrate operation of magnetically triggered stages. Study of TPOS characteristics is in progress via an offline interferometer diagnostic; specifically, a laser interferometer will be used to make density measurements of the source plasma. It is thought that the gross plasma source density is {approx}10{sup 14} cm{sup -3}, but details of the spatial structure and temporal evolution have not previously been studied. In order to better understand switch operation, these details are essential. Presently two interferometer systems are planned for testing: a temporary 1 mum system for initial plasma characterization, and a 10.6 mum laser system for routine use. We will start with a single chord measurement then upgrade to a multi-chord system. Future plans involve varying plasma source parameters, such as magnetic field strength and plasma fill time, in order to understand the density dependence on these parameters. Improved knowledge of the plasma source density behavior should allow for improved switch operation.

  15. Turbulence measurements in high-speed wind tunnels using focusing laser differential interferometry

    NASA Astrophysics Data System (ADS)

    Fulghum, Matthew R.

    Characterization of freestream disturbances and their effect on laminar boundary layer transition is of great importance in high-speed wind tunnel testing, where significant differences between the behavior of scale-model and free-flight transition have long been noted. However, the methods traditionally used to perform this characterization in low-speed flows present significant difficulties when applied to supersonic and especially hypersonic wind tunnels. The design and theory of a focusing laser differential interferometer (FLDI) instrument, originally invented by Smeets at the Institut Saint-Louis in the 1970s and used recently by Parziale in the CalTech T5 shock tunnel, is presented. It is a relatively-simple, non-imaging common-path interferometer for measuring refractive signals from transition and turbulence, and it has a unique ability to look through facility windows, ignore sidewall boundary-layers and vibration, and concentrate only on the refractive signal near a pair of sharp beam foci in the core flow. The instrument's low cost and ease of implementation make it a promising alternative to traditional hot-wire anemometry and particle-based methods for turbulence characterization. Benchtop experiments using a turbulent supersonic air jet demonstrate its focusing ability, frequency response, unwanted signal rejection, and ease of use. The instrument is used to optically interrogate the flow in the Penn State University Supersonic Wind Tunnel and USAF AEDC Hypervelocity Tunnel 9 for measurement of the overall intensity and spectra of freestream disturbances. Precise characterization of the strength and spectral content of the disturbances provides insight into their nature and potential effect upon boundary layer transition. A special feature of the FLDI instrument used here is the replacement of traditional fixed Wollaston prisms with variable Sanderson prisms for laser-beam separation and recombination.

  16. Digital stroboscopic holographic interferometry for power flow measurements in acoustically driven membranes

    NASA Astrophysics Data System (ADS)

    Keustermans, William; Pires, Felipe; De Greef, Daniël; Vanlanduit, Steve J. A.; Dirckx, Joris J. J.

    2016-06-01

    Despite the importance of the eardrum and the ossicles in the hearing chain, it remains an open question how acoustical energy is transmitted between them. Identifying the transmission path at different frequencies could lead to valuable information for the domain of middle ear surgery. In this work a setup for stroboscopic holography is combined with an algorithm for power flow calculations. With our method we were able to accurately locate the power sources and sinks in a membrane. The setup enabled us to make amplitude maps of the out-of-plane displacement of a vibrating rubber membrane at subsequent instances of time within the vibration period. From these, the amplitude maps of the moments of force and velocities are calculated. The magnitude and phase maps are extracted from this amplitude data, and form the input for the power flow calculations. We present the algorithm used for the measurements and for the power flow calculations. Finite element models of a circular plate with a local energy source and sink allowed us to test and optimize this algorithm in a controlled way and without the present of noise, but will not be discussed below. At the setup an earphone was connected with a thin tube which was placed very close to the membrane so that sound impinges locally on the membrane, hereby acting as a local energy source. The energy sink was a little piece of foam carefully placed against the membrane. The laser pulses are fired at selected instants within the vibration period using a 30 mW HeNe continuous wave laser (red light, 632.8 nm) in combination with an acousto-optic modulator. A function generator controls the phase of these illumination pulses and the holograms are recorded using a CCD camera. We present the magnitude and phase maps as well as the power flow measurements on the rubber membrane. Calculation of the divergence of this power flow map provides a simple and fast way of identifying and locating an energy source or sink. In conclusion

  17. Sub-shot-noise interferometry from measurements of the one-body density

    NASA Astrophysics Data System (ADS)

    Chwedeńczuk, J.; Hyllus, P.; Piazza, F.; Smerzi, A.

    2012-09-01

    We derive the asymptotic maximum-likelihood phase estimation uncertainty for any interferometric protocol where the positions of the probe particles are measured to infer the phase, but where correlations between the particles are not accessible. First, we apply our formula to the estimation of the phase acquired in the Mach-Zehnder interferometer and recover the well-known momentum formula for the phase sensitivity. Then, we apply our results to interferometers with two spatially separated modes, which could be implemented with a Bose-Einstein condensate trapped in a double-well potential. We show that in a simple protocol which estimates the phase from an interference pattern, a sub-shot-noise phase uncertainty of up to Δθ∝N-2/3 can be achieved. One important property of this estimation protocol is that its sensitivity does not depend on the value of the phase θ, contrary to the sensitivity given by the momentum formula for the Mach-Zehnder transformation. Finally, we study the experimental implementation of the above protocol in detail, by numerically simulating the full statistics as well as by considering the main sources of detection noise, and argue that the shot-noise limit could be surpassed with current technology.

  18. Electron kinetic effects on interferometry, polarimetry and Thomson scattering measurements in burning plasmas (invited).

    PubMed

    Mirnov, V V; Brower, D L; Den Hartog, D J; Ding, W X; Duff, J; Parke, E

    2014-11-01

    At anticipated high electron temperatures in ITER, the effects of electron thermal motion on Thomson scattering (TS), toroidal interferometer/polarimeter (TIP), and poloidal polarimeter (PoPola) diagnostics will be significant and must be accurately treated. The precision of the previous lowest order linear in τ = Te/mec(2) model may be insufficient; we present a more precise model with τ(2)-order corrections to satisfy the high accuracy required for ITER TIP and PoPola diagnostics. The linear model is extended from Maxwellian to a more general class of anisotropic electron distributions that allows us to take into account distortions caused by equilibrium current, ECRH, and RF current drive effects. The classical problem of the degree of polarization of incoherent Thomson scattered radiation is solved analytically exactly without any approximations for the full range of incident polarizations, scattering angles, and electron thermal motion from non-relativistic to ultra-relativistic. The results are discussed in the context of the possible use of the polarization properties of Thomson scattered light as a method of Te measurement relevant to ITER operational scenarios. PMID:25430162

  19. Electron kinetic effects on interferometry, polarimetry and Thomson scattering measurements in burning plasmas (invited)

    SciTech Connect

    Mirnov, V. V.; Hartog, D. J. Den; Duff, J.; Parke, E.; Brower, D. L.; Ding, W. X.

    2014-11-15

    At anticipated high electron temperatures in ITER, the effects of electron thermal motion on Thomson scattering (TS), toroidal interferometer/polarimeter (TIP), and poloidal polarimeter (PoPola) diagnostics will be significant and must be accurately treated. The precision of the previous lowest order linear in τ = T{sub e}/m{sub e}c{sup 2} model may be insufficient; we present a more precise model with τ{sup 2}-order corrections to satisfy the high accuracy required for ITER TIP and PoPola diagnostics. The linear model is extended from Maxwellian to a more general class of anisotropic electron distributions that allows us to take into account distortions caused by equilibrium current, ECRH, and RF current drive effects. The classical problem of the degree of polarization of incoherent Thomson scattered radiation is solved analytically exactly without any approximations for the full range of incident polarizations, scattering angles, and electron thermal motion from non-relativistic to ultra-relativistic. The results are discussed in the context of the possible use of the polarization properties of Thomson scattered light as a method of T{sub e} measurement relevant to ITER operational scenarios.

  20. Reverse transduction measured in the living cochlea by low-coherence heterodyne interferometry

    PubMed Central

    Ren, Tianying; He, Wenxuan; Barr-Gillespie, Peter G.

    2016-01-01

    It is generally believed that the remarkable sensitivity and frequency selectivity of mammalian hearing depend on outer hair cell-generated force, which amplifies sound-induced vibrations inside the cochlea. This ‘reverse transduction' force production has never been demonstrated experimentally, however, in the living ear. Here by directly measuring microstructure vibrations inside the cochlear partition using a custom-built interferometer, we demonstrate that electrical stimulation can evoke both fast broadband and slow sharply tuned responses of the reticular lamina, but only a slow tuned response of the basilar membrane. Our results indicate that outer hair cells can generate sufficient force to drive the reticular lamina over all audible frequencies in living cochleae. Contrary to expectations, the cellular force causes a travelling wave rather than an immediate local vibration of the basilar membrane; this travelling wave vibrates in phase with the reticular lamina at the best frequency, and results in maximal vibration at the apical ends of outer hair cells. PMID:26732830

  1. Quantum Interferometry

    NASA Technical Reports Server (NTRS)

    Dowling, Jonathan P.

    2000-01-01

    Recently, several researchers, including yours truly, have been able to demonstrate theoretically that quantum photon entanglement has the potential to also revolutionize the entire field of optical interferometry, by providing many orders of magnitude improvement in interferometer sensitivity. The quantum entangled photon interferometer approach is very general and applies to many types of interferometers. In particular, without nonlocal entanglement, a generic classical interferometer has a statistical-sampling shot-noise limited sensitivity that scales like 1/Sqrt[N], where N is the number of particles (photons, electrons, atoms, neutrons) passing through the interferometer per unit time. However, if carefully prepared quantum correlations are engineered between the particles, then the interferometer sensitivity improves by a factor of Sqrt[N] (square root of N) to scale like 1/N, which is the limit imposed by the Heisenberg Uncertainty Principle. For optical (laser) interferometers operating at milliwatts of optical power, this quantum sensitivity boost corresponds to an eight-order-of-magnitude improvement of signal to noise. Applications are to tests of General Relativity such as ground and orbiting optical interferometers for gravity wave detection, Laser Interferometer Gravity Observatory (LIGO) and the European Laser Interferometer Space Antenna (LISA), respectively.

  2. History of Stellar Interferometry

    NASA Technical Reports Server (NTRS)

    Lawson, Peter R.

    2004-01-01

    This viewgraph presentation reviews the history of stellar interferometry from the suggestion of Fizeau that stellar interferometry was possible,to the use of the Mark I, II and III for astrometry. Photographs, and parts of original articles are presented.

  3. Electronic Speckle Pattern Interferometry

    NASA Astrophysics Data System (ADS)

    Lokberg, Ole J.

    1988-01-01

    The basic principles of electronic speckle pattern interferometry (ESPI) are described, stressing its close similarity to hologram interferometry. The technique's applications for vibration and deformation testing within industrial and medical research are outlined. Future developments are discussed.

  4. Phase-velocity measurement of surface waves beneath the Philippine Sea from the ambient seismic noise interferometry

    NASA Astrophysics Data System (ADS)

    Takeo, A.; Nishida, K.; Kawakatsu, H.; Isse, T.; Shiobara, H.; Kanazawa, T.; Sugioka, H.

    2010-12-01

    The radial anisotropy within the oceanic lithosphere appears weaker than that in the asthenosphere, and various origins for this difference are proposed, such as high shear (Nettles and Dziewonski, 2008) or thin melt layers (Kawakatsu et al., 2009) in the asthenosphere. Tomography studies using surface waves, however, usually analyze periods longer than 35-40 sec, and have limited resolution for the lithosphere. To measure phase velocities of Love and Rayleigh waves at shorter periods, we apply the ambient seismic noise interferometry to continuous data of three-component broadband ocean bottom seismometers operated for 2-3 years at 11 stations in the Philippine Sea. We first calculate time-averaged cross-correlation functions between all pairs of stations, and plot them against the separation distances between pairs of stations. As a result, three types of surface waves are identified from three combinations of components: (1) the fundamental mode of Love wave from transverse component pairs, (2) the first higher mode of Rayleigh wave from radial component pairs, and (3) the fundamental mode of Rayleigh wave from vertical component pairs. We then select seven stations in Shikoku Basin, Philippine Sea, and search for an optimum phase velocity by fitting the Bessel function to cross-spectra for each frequency (Aki, 1957; Nishida et al., 2008). The period of resultant phase velocities ranges 8-25 sec for the Love wave, 7-11 sec for the first higher mode Rayleigh wave, and 12-50 sec for the fundamental mode Rayleigh wave. For example, the phase velocities of Love wave vary from 4.3 km/s (at 8 sec) to 4.6 km/s (at 25 sec). These values are 0.2-0.3 km/s higher than those predicted by one-dimensional model of Philippine Sea, PHB3 (Kato and Jordan, 1998), indicating an additional constraint on the shallow structure. Combining these data with long-period phase velocities derived from seismic event analysis, we will present a one-dimensional model of the radial anisotropy

  5. Development of dual-wavelength fiber ring laser and its application to step-height measurement using self-mixing interferometry.

    PubMed

    Ma, S; Xie, F; Chen, L; Wang, Y Z; Dong, L L; Zhao, K Q

    2016-03-21

    A dual-wavelength erbium-doped fiber (EDF) ring laser was developed and its application to step-height measurement using two-wavelength self-mixing interferometry (SMI) was demonstrated. The fiber laser can emit two different wavelengths without any laser mode competition. It is composed of two EDF laser cavities and employs fiber Bragg gratings to determine which wavelengths are emitted. The step heights can be measured using SMI of the two wavelengths, and the maximum height that can be measured is half the synthetic wavelength of the two wavelengths. A step height of 1mm was constructed using two gauge blocks and then measured using the laser. The measurement was repeated ten times, and the standard deviation of the measurements was 2.4nm. PMID:27136766

  6. Ground-Based Real-Aperture Radar Interferometry: Techniques and Potential for Measurement of mm-Scale Motion

    NASA Astrophysics Data System (ADS)

    Werner, C. L.; Wiesmann, A.; Kos, A.; Caduff, R.; Strozzi, T.; Wegmüller, U.

    2011-12-01

    Ground-based radar interferometry is an emerging geodetic imaging technology that has been applied to measurement of landslides, rockfalls, glaciers, and mines. Geo-technical observations have been performed of infrastructure including bridges and dams. Compared with spaceborne radar systems, ground-based observations have advantages with respect to the selection of the imaging geometry to optimize visibility and sensitivity to deformation, shorter repeat intervals for monitoring rapidly moving features, and higher sensitivity to motion along the line-of-sight (LOS) due to the shorter wavelength and potential for averaging of multiple observations. The GPRI instrument developed by Gamma Remote Sensing is an FM-CW radar operating at 17.2 GHz (λ: 17.4 mm) with a range resolution of 90 cm along the line of sight and an operational range from 20 meters to 16 km. The GPRI is a real-aperture instrument using a 2.06 m long waveguide antenna to generate a fan-beam that is 0.4 x 35 degrees. During data acquisition, the radar performs a rotary scan of the scene at a programmable rate between 0.5 and 10 degrees/sec. Azimuth resolution is linearly proportional to slant range with a value of 7m at 1 km distance. Differential motion of 8.71 mm results in 2PI radians of measurable phase between observations. The GPRI incorporates two receivers enabling simultaneous interferometric observation with a vertical baseline variable between 25 and 60 cm. The single transmitting antenna and 2 receiving antennas are mounted parallel to one another on a rigid tower attached to a rotary positioner. An internal GPS receiver provides a time and frequency reference permitting simultaneous operation of multiple GPRI systems. The GPRI operates in four possible data acquisition modes permitting a wide range of applications. The first mode is the simultaneous interferometric mode using the upper and lower receiving antennas. The interferometric phase can be used to derive an elevation model

  7. Temperature-fluctuation-sensitive accumulative effect of the phase measurement errors in low-coherence interferometry in characterizing arrayed waveguide gratings.

    PubMed

    Zhao, Changyun; Wei, Bing; Yang, Longzhi; Wang, Gencheng; Wang, Yuehai; Jiang, Xiaoqing; Li, Yubo; Yang, Jianyi

    2015-09-20

    We investigate the accumulative effect of the phase measurement errors in characterizing optical multipath components by low-coherence interferometry. The accumulative effect is caused by the fluctuation of the environment temperature, which leads to the variation of the refractive index of the device under test. The resulting phase measurement errors accumulate with the increasing of the phase difference between the two interferometer arms. Our experiments were carried out to demonstrate that the accumulative effect is still obvious even though the thermo-optical coefficient of the device under test is quite small. Shortening the measurement time to reduce the fluctuation of the environment temperature can effectively restrain the accumulative effect. The experiments show that when the scanning speed increases to 4.8 mm/s, the slope of the phase measurement errors decreases to 5.52×10(-8), which means the accumulative effect can be ignored. PMID:26406502

  8. High-frequency fluctuation measurements by far-infrared laser Faraday-effect polarimetry-interferometry and forward scattering system on MST

    SciTech Connect

    Ding, W. X. Lin, L.; Brower, D. L.; Duff, J. R.

    2014-11-15

    Magnetic fluctuation-induced transport driven by global tearing modes has been measured by Faraday-effect polarimetry and interferometry (phase measurements) in the MST reversed field pinch. However, the role of small-scale broadband magnetic and density turbulence in transport remains unknown. In order to investigate broadband magnetic turbulence, we plan to upgrade the existing detector system by using planar-diode fundamental waveguide mixers optimized for high sensitivity. Initial tests indicate these mixers have ×10 sensitivity improvement compared to currently employed corner-cube Schottky-diode mixers and ×5 lower noise. Compact mixer design will allow us to resolve the wavenumbers up to k ∼ 1–2 cm{sup −1} for beam width w = 1.5 cm and 15 cm{sup −1} for beam width w = 2 mm. The system can also be used to measure the scattered signal (amplitude measurement) induced by both plasma density and magnetic fluctuations.

  9. Tilt scanning interferometry: a 3D k-space representation for depth-resolved structure and displacement measurement in scattering materials

    NASA Astrophysics Data System (ADS)

    Galizzi, Gustavo E.; Coupland, Jeremy M.; Ruiz, Pablo D.

    2010-09-01

    Tilt Scanning Interferometry (TSI) has been recently developed as an experimental method to measure multi-component displacement fields inside the volume of semitransparent scattering materials. It can be considered as an extension of speckle interferometry in 3D, in which the illumination angle is tilted to provide depth information, or as an optical diffraction tomography technique with phase detection. It relies on phase measurements to extract the displacement information, as in the usual 2D counterparts. A numerical model to simulate the speckle fields recorded in TSI has been recently developed to enable the study on how the phase and amplitude are affected by factors such as refraction, absorption, scattering, dispersion, stress-optic coupling and spatial variations of the refractive index, all of which may lead to spurious displacements. In order to extract depth-resolved structure and phase information from TSI data, the approach had been to use Fourier Transformation of the intensity modulation signal along the illumination angle axis. However, it turns out that a more complete description of the imaging properties of the system for tomographic optical diffraction can be achieved using a 3D representation of the transfer function in k-space. According to this formalism, TSI is presented as a linear filtering operation. In this paper we describe the transfer function of TSI in 3D k-space, evaluate the 3D point spread function and present simulated results.

  10. Time-Delay Interferometry

    NASA Astrophysics Data System (ADS)

    Dhurandhar, Sanjeev V.; Tinto, Massimo

    2005-07-01

    Equal-arm interferometric detectors of gravitational radiation allow phase measurements many orders of magnitude below the intrinsic phase stability of the laser injecting light into their arms. This is because the noise in the laser light is common to both arms, experiencing exactly the same delay, and thus cancels when it is differenced at the photo detector. In this situation, much lower level secondary noises then set the overall performance. If, however, the two arms have different lengths (as will necessarily be the case with space-borne interferometers), the laser noise experiences different delays in the two arms and will hence not directly cancel at the detector. In order to solve this problem, a technique involving heterodyne interferometry with unequal arm lengths and independent phase-difference readouts has been proposed. It relies on properly time-shifting and linearly combining independent Doppler measurements, and for this reason it has been called Time-Delay Interferometry (TDI). This article provides an overview of the theory and mathematical foundations of TDI as it will be implemented by the forthcoming space-based interferometers such as the Laser Interferometer Space Antenna (LISA) mission. We have purposely left out from this first version of our "Living Review" article on TDI all the results of more practical and experimental nature, as well as all the aspects of TDI that the data analysts will need to account for when analyzing the LISA TDI data combinations. Our forthcoming "second edition" of this review paper will include these topics.

  11. Advances in ice radar studies of a temperate alpine glacier, South Cascade Glacier, Washington, U.S.A.

    USGS Publications Warehouse

    Fountain, A.G.; Jacobel, R.W.

    1997-01-01

    South Cascade Glacier, Washington, U.S.A., is one of the most extensively studied glaciers in the Western Hemisphere. In addition to mass-balance measurements, which date to 1958, numerous hydrological investigations have been carried out during the last three decades, and repeated ice-thickness determinations have been made using a variety of techniques. In the late 1960s, the basal topography was initially determined by gravitimetric methods. In the mid-1970s some of the first depth measurements using radar on temperate ice were made. The basal topography was remapped soon after from a series of point radar measurements and boreholes drilled to the glacier bottom. During the 1990s, the ice thickness was remapped using digital recording of continuous profiles that obtained over 5000 ice-thickness measurements. Profiles have been corrected for the finite beamwidth of the antenna radiation pattern and reflections in steep terrain, resulting in a significantly improved depiction of the basal surface and internal structures. The map based on our recent radar profiles confirms the large-scale features of the basal topography previously depicted and reveals more structural detail. A bright reflector was detected at the base of the glacier and could be traced in adjacent profiles. Comparison with results from water-level measurements in boreholes drilled to the bed indicates that the reflector is a subglacial conduit.

  12. Combined x-ray scattering, radiography, and velocity interferometry/streaked optical pyrometry measurements of warm dense carbon using a novel technique of shock-and-release

    SciTech Connect

    Falk, K.; Collins, L. A.; Kagan, G.; Kress, J. D.; Montgomery, D. S.; Srinivasan, B.; Gamboa, E. J.; Tzeferacos, P.; Benage, J. F.

    2014-05-15

    This work focused on a new application of the shock-and-release technique for equation of state (EOS) measurements. Warm dense matter states at near normal solid density and at temperatures close to 10 eV in diamond and graphite samples were created using a deep release from a laser-driven shock at the OMEGA laser facility. Independent temperature, density, and pressure measurements that do not depend on any theoretical models or simulations were obtained using imaging x-ray Thomson scattering, radiography, velocity interferometry, and streaked optical pyrometry. The experimental results were reproduced by the 2-D FLASH radiation hydrodynamics simulations finding a good agreement. The final EOS measurement was then compared with widely used SESAME EOS models as well as quantum molecular dynamics simulation results for carbon, which were very consistent with the experimental data.

  13. Measurement of the He-McKellar-Wilkens topological phase by atom interferometry and test of its independence with atom velocity.

    PubMed

    Gillot, J; Lepoutre, S; Gauguet, A; Büchner, M; Vigué, J

    2013-07-19

    In this Letter, we report a measurement of the He-McKellar-Wilkens (HMW) topological phase by atom interferometry. The experiment is done with our lithium atom interferometer, and in order to suppress the stray effects present in our first experiment, we use optical pumping of the (7)Li atoms in their F=2, m(F)=+2 (or -2) ground state sublevel. In these conditions, the measured phase shift is the sum of the HMW phase and of the Aharonov-Casher phase, which are separated due to their different m(F) dependence. The HMW phase has been measured for different lithium beam velocities and the results are in very good agreement with a phase independent of the atom velocity, as expected for a topological phase. PMID:23909295

  14. Single-Shot Measurement of Temporally-Dependent Polarization State of Femtosecond Pulses by Angle-Multiplexed Spectral-Spatial Interferometry

    PubMed Central

    Lin, Ming-Wei; Jovanovic, Igor

    2016-01-01

    We demonstrate that temporally-dependent polarization states of ultrashort laser pulses can be reconstructed in a single shot by use of an angle-multiplexed spatial-spectral interferometry. This is achieved by introducing two orthogonally polarized reference pulses and interfering them with an arbitrarily polarized ultrafast pulse under measurement. A unique calibration procedure is developed for this technique which facilitates the subsequent polarization state measurements. The accuracy of several reconstructed polarization states is verified by comparison with that obtained from an analytic model that predicts the polarization state on the basis of its method of production. Laser pulses with mJ-level energies were characterized via this technique, including a time-dependent polarization state that can be used for polarization-gating of high-harmonic generation for production of attosecond pulses. PMID:27596951

  15. Single-Shot Measurement of Temporally-Dependent Polarization State of Femtosecond Pulses by Angle-Multiplexed Spectral-Spatial Interferometry.

    PubMed

    Lin, Ming-Wei; Jovanovic, Igor

    2016-01-01

    We demonstrate that temporally-dependent polarization states of ultrashort laser pulses can be reconstructed in a single shot by use of an angle-multiplexed spatial-spectral interferometry. This is achieved by introducing two orthogonally polarized reference pulses and interfering them with an arbitrarily polarized ultrafast pulse under measurement. A unique calibration procedure is developed for this technique which facilitates the subsequent polarization state measurements. The accuracy of several reconstructed polarization states is verified by comparison with that obtained from an analytic model that predicts the polarization state on the basis of its method of production. Laser pulses with mJ-level energies were characterized via this technique, including a time-dependent polarization state that can be used for polarization-gating of high-harmonic generation for production of attosecond pulses. PMID:27596951

  16. Readout for intersatellite laser interferometry: Measuring low frequency phase fluctuations of high-frequency signals with microradian precision

    NASA Astrophysics Data System (ADS)

    Gerberding, Oliver; Diekmann, Christian; Kullmann, Joachim; Tröbs, Michael; Bykov, Ioury; Barke, Simon; Brause, Nils Christopher; Esteban Delgado, Juan José; Schwarze, Thomas S.; Reiche, Jens; Danzmann, Karsten; Rasmussen, Torben; Hansen, Torben Vendt; Enggaard, Anders; Pedersen, Søren Møller; Jennrich, Oliver; Suess, Martin; Sodnik, Zoran; Heinzel, Gerhard

    2015-07-01

    Precision phase readout of optical beat note signals is one of the core techniques required for intersatellite laser interferometry. Future space based gravitational wave detectors like eLISA require such a readout over a wide range of MHz frequencies, due to orbit induced Doppler shifts, with a precision in the order of μ rad / √{ Hz } at frequencies between 0.1 mHz and 1 Hz. In this paper, we present phase readout systems, so-called phasemeters, that are able to achieve such precisions and we discuss various means that have been employed to reduce noise in the analogue circuit domain and during digitisation. We also discuss the influence of some non-linear noise sources in the analogue domain of such phasemeters. And finally, we present the performance that was achieved during testing of the elegant breadboard model of the LISA phasemeter, which was developed in the scope of a European Space Agency technology development activity.

  17. Deep frequency modulation interferometry.

    PubMed

    Gerberding, Oliver

    2015-06-01

    Laser interferometry with pm/Hz precision and multi-fringe dynamic range at low frequencies is a core technology to measure the motion of various objects (test masses) in space and ground based experiments for gravitational wave detection and geodesy. Even though available interferometer schemes are well understood, their construction remains complex, often involving, for example, the need to build quasi-monolithic optical benches with dozens of components. In recent years techniques have been investigated that aim to reduce this complexity by combining phase modulation techniques with sophisticated digital readout algorithms. This article presents a new scheme that uses strong laser frequency modulations in combination with the deep phase modulation readout algorithm to construct simpler and easily scalable interferometers. PMID:26072834

  18. Quasi-Heterodyne Hologram Interferometry

    NASA Astrophysics Data System (ADS)

    Hariharan, P.

    1985-08-01

    Wider use of hologram interferometry for quantitative measure-ments has been delayed by the fact that interpolation between the fringe maxima and minima to obtain the optical path difference at a particular point in the field is laborious and inaccurate. A solution to this problem is quasi-hetero-dyne interferometry, which permits rapid and accurate measurements simultaneously at a number of points distributed over the interference pattern. In this technique a television camera is used in conjunction with digital electronics to measure and store the irradiance values at points on a rectangular sampling grid covering the real-time interference fringes. The phase difference between the interfering wavefronts at each point is then calculated from the irradiance values obtained from successive scans of the camera made while the phase of one of the wavefronts is shifted either continuously or in steps. A practical system is described with which values of the optical path difference for 10,000 data points can be obtained with an accuracy of +/- A/200 in less than 10 s. The application of quasi-heterodyne hologram interferometry to the measurement of vector displacements and to holographic contouring is discussed.

  19. Virtually calibrated projection moire interferometry.

    PubMed

    Kimber, Mark; Blotter, Jonathan

    2005-05-01

    Projection moire interferometry (PMI) is an out-of-plane displacement measurement technique that consists of differencing reference and deformed images of a grid pattern projected onto the test object. In conventional PMI, a tedious process of computing the fringe sensitivity coefficient (FSC), which requires moving the test object or the reference plane to known displacements, is used. We present a new technique for computing the FSC values that is called virtually calibrated projection moire interferometry (VCPMI). VCPMI is based on computer simulations of the conventional PMI process and does not require moving the actual test object or reference plane. We validate the VCPMI approach by comparing results for a flat plate and an airfoil with those made by use of other measurement methods. PMID:15881060

  20. Electronic speckle pattern interferometry and digital holographic interferometry with microbolometer arrays at 10.6 {mu}m

    SciTech Connect

    Vandenrijt, Jean-Francois; Georges, Marc P.

    2010-09-20

    Electronic speckle pattern interferometry and digital holographic interferometry are investigated at long infrared wavelengths. Using such wavelengths allows one to extend the measurement range and decrease the sensitivity of the techniques to external perturbations. We discuss the behavior of reflection by the object surfaces due to the long wavelength. We have developed different experimental configurations associating a CO2 laser emitting at 10.6{mu}m and microbolometer arrays. Phase-shifting in-plane and out-of-plane electronic speckle pattern interferometry and lensless digital holographic interferometry are demonstrated on rotation measurements of a solid object.

  1. Toward robust deconvolution of pass-through paleomagnetic measurements: new tool to estimate magnetometer sensor response and laser interferometry of sample positioning accuracy

    NASA Astrophysics Data System (ADS)

    Oda, Hirokuni; Xuan, Chuang; Yamamoto, Yuhji

    2016-07-01

    Pass-through superconducting rock magnetometers (SRM) offer rapid and high-precision remanence measurements for continuous samples that are essential for modern paleomagnetism studies. However, continuous SRM measurements are inevitably smoothed and distorted due to the convolution effect of SRM sensor response. Deconvolution is necessary to restore accurate magnetization from pass-through SRM data, and robust deconvolution requires reliable estimate of SRM sensor response as well as understanding of uncertainties associated with the SRM measurement system. In this paper, we use the SRM at Kochi Core Center (KCC), Japan, as an example to introduce new tool and procedure for accurate and efficient estimate of SRM sensor response. To quantify uncertainties associated with the SRM measurement due to track positioning errors and test their effects on deconvolution, we employed laser interferometry for precise monitoring of track positions both with and without placing a u-channel sample on the SRM tray. The acquired KCC SRM sensor response shows significant cross-term of Z-axis magnetization on the X-axis pick-up coil and full widths of ~46-54 mm at half-maximum response for the three pick-up coils, which are significantly narrower than those (~73-80 mm) for the liquid He-free SRM at Oregon State University. Laser interferometry measurements on the KCC SRM tracking system indicate positioning uncertainties of ~0.1-0.2 and ~0.5 mm for tracking with and without u-channel sample on the tray, respectively. Positioning errors appear to have reproducible components of up to ~0.5 mm possibly due to patterns or damages on tray surface or rope used for the tracking system. Deconvolution of 50,000 simulated measurement data with realistic error introduced based on the position uncertainties indicates that although the SRM tracking system has recognizable positioning uncertainties, they do not significantly debilitate the use of deconvolution to accurately restore high

  2. Readout for intersatellite laser interferometry: Measuring low frequency phase fluctuations of high-frequency signals with microradian precision.

    PubMed

    Gerberding, Oliver; Diekmann, Christian; Kullmann, Joachim; Tröbs, Michael; Bykov, Ioury; Barke, Simon; Brause, Nils Christopher; Esteban Delgado, Juan José; Schwarze, Thomas S; Reiche, Jens; Danzmann, Karsten; Rasmussen, Torben; Hansen, Torben Vendt; Enggaard, Anders; Pedersen, Søren Møller; Jennrich, Oliver; Suess, Martin; Sodnik, Zoran; Heinzel, Gerhard

    2015-07-01

    Precision phase readout of optical beat note signals is one of the core techniques required for intersatellite laser interferometry. Future space based gravitational wave detectors like eLISA require such a readout over a wide range of MHz frequencies, due to orbit induced Doppler shifts, with a precision in the order of μrad/√Hz at frequencies between 0.1 mHz and 1 Hz. In this paper, we present phase readout systems, so-called phasemeters, that are able to achieve such precisions and we discuss various means that have been employed to reduce noise in the analogue circuit domain and during digitisation. We also discuss the influence of some non-linear noise sources in the analogue domain of such phasemeters. And finally, we present the performance that was achieved during testing of the elegant breadboard model of the LISA phasemeter, which was developed in the scope of a European Space Agency technology development activity. PMID:26233398

  3. Comparison of Anterior Segment Measurements with Scheimpflug/Placido Photography-Based Topography System and IOLMaster Partial Coherence Interferometry in Patients with Cataracts

    PubMed Central

    Huang, Jinhai; Liao, Na; Bao, Fangjun; Yu, Ye; Lu, Weicong; Hu, Qingjie; Wang, Qinmei

    2014-01-01

    Purpose. To assess the consistency of anterior segment measurements obtained using a Sirius Scheimpflug/Placido photography-based topography system (CSO, Italy) and IOLMaster partial coherence interferometry (Carl Zeiss Meditec, Germany) in eyes with cataracts. Methods. A total of 90 eyes of 90 patients were included in this prospective study. The anterior chamber depth (ACD), keratometry (K), corneal astigmatism axis, and white to white (WTW) values were randomly measured three times with Sirius and IOLMaster. Concordance between them was assessed by calculating 95% limits of agreement (LoA). Results. The ACD and K taken with the Sirius were statistically significantly higher than that taken with the IOLMaster; however, the Sirius significantly underestimated the WTW values compared with the IOLMaster. Good agreement was found for Km and ACD measurements, with 95% LoA of −0.20 to 0.54 mm and −0.16 to 0.34 mm, respectively. Poor agreement was observed for astigmatism axis and WTW measurements, as the 95% LoA was −23.96 to 23.36° and −1.15 to 0.37 mm, respectively. Conclusion. With the exception of astigmatism axis and WTW, anterior segment measurements taken by Sirius and IOLMaster devices showed good agreement and may be used interchangeably in patients with cataracts. PMID:25400939

  4. Extreme ultraviolet interferometry

    SciTech Connect

    Goldberg, K A

    1997-12-01

    EUV lithography is a promising and viable candidate for circuit fabrication with 0.1-micron critical dimension and smaller. In order to achieve diffraction-limited performance, all-reflective multilayer-coated lithographic imaging systems operating near 13-nm wavelength and 0.1 NA have system wavefront tolerances of 0.27 nm, or 0.02 waves RMS. Owing to the highly-sensitive resonant reflective properties of multilayer mirrors and extraordinarily tight tolerances set forth for their fabrication, EUV optical systems require at-wavelength EUV interferometry for final alignment and qualification. This dissertation discusses the development and successful implementation of high-accuracy EUV interferometric techniques. Proof-of-principle experiments with a prototype EUV point-diffraction interferometer for the measurement of Fresnel zoneplate lenses first demonstrated sub-wavelength EUV interferometric capability. These experiments spurred the development of the superior phase-shifting point-diffraction interferometer (PS/PDI), which has been implemented for the testing of an all-reflective lithographic-quality EUV optical system. Both systems rely on pinhole diffraction to produce spherical reference wavefronts in a common-path geometry. Extensive experiments demonstrate EUV wavefront-measuring precision beyond 0.02 waves RMS. EUV imaging experiments provide verification of the high-accuracy of the point-diffraction principle, and demonstrate the utility of the measurements in successfully predicting imaging performance. Complementary to the experimental research, several areas of theoretical investigation related to the novel PS/PDI system are presented. First-principles electromagnetic field simulations of pinhole diffraction are conducted to ascertain the upper limits of measurement accuracy and to guide selection of the pinhole diameter. Investigations of the relative merits of different PS/PDI configurations accompany a general study of the most significant sources

  5. Highspeed multiplexed heterodyne interferometry.

    PubMed

    Isleif, Katharina-S; Gerberding, Oliver; Köhlenbeck, Sina; Sutton, Andrew; Sheard, Benjamin; Goßler, Stefan; Shaddock, Daniel; Heinzel, Gerhard; Danzmann, Karsten

    2014-10-01

    Digitally enhanced heterodyne interferometry is a metrology technique that uses pseudo-random noise codes for modulating the phase of the laser light. Multiple interferometric signals from the same beam path can thereby be isolated based on their propagation delay, allowing one to use advantageous optical layouts in comparison to classic laser interferometers. We present here a high speed version of this technique for measuring multiple targets spatially separated by only a few centimetres. This allows measurements of multiplexed signals using free beams, making the technique attractive for several applications requiring compact optical set-ups like for example space-based interferometers. In an experiment using a modulation and sampling rate of 1.25 GHz we are able to demonstrate multiplexing between targets only separated by 36 cm and we achieve a displacement measurement noise floor of <3 pm/√Hz at 10 Hz between them. We identify a limiting excess noise at low frequencies which is unique to this technique and is probably caused by the finite bandwidth in our measurement set-up. Utilising an active clock jitter correction scheme we are also able to reduce this noise in a null measurement configuration by one order of magnitude. PMID:25322043

  6. The equation of state of 5-nitro-2,4-dihydro-1,2,4,-triazol-3-one determined via in-situ optical microscopy and interferometry measurements

    DOE PAGESBeta

    Stavrou, Elissaios; Zaug, Joseph M.; Bastea, Sorin; Crowhurst, Jonathan C.

    2016-04-07

    Quasi-hydrostatic high-pressure equations of state (EOS) are typically determined, for crystalline solids, by measuring unit-cell volumes using x-ray diffraction (XRD) techniques. However, when characterizing low-symmetry materials with large unit cells, conventional XRD approaches may become problematic. To overcome this issue, we examined the utility of a "direct" approach toward determining high pressure material volume by measuring surface area and sample thickness using optical microscopy and interferometry (OMI) respectively. We have validated this experimental approach by comparing results obtained for TATB (2,4,6-triamino-1,3,5-trinitrobenzene) with an EOS determined from synchrotron XRD measurements; and, a good match is observed. We have measured the highmore » pressure EOS of 5-nitro-2,4-dihydro-1,2,4-triazol-3-one (α-NTO) up to 33 GPa. No high-pressure XRD EOS data have been published on α-NTO, probably due to its complex crystal structure. Furthermore, the results of this study suggest that OMI is a reliable and versatile alternative for determining EOSs, especially when conventional methodologies are impractical.« less

  7. Small scale ground deformations observed in the western rift of Corinth by exploiting multitemporal interferometry and GPS measurements

    NASA Astrophysics Data System (ADS)

    Elias, Panagiotis; Briole, Pierre

    2014-05-01

    The rift of Corinth has been long identified as a site of major importance in Europe due to its intense tectonic activity. It is one of the world's most rapidly extending continental regions and it has one of the highest seismicity rates in the Euro-Mediterranean region. The GPS studies conducted since 1990 indicate a north-south extension rate across the rift of about 1.5 cm/yr around its western termination. The western termination of the rift in the Patras broader area presents a major scientific and socio-economic importance, with the Psathopyrgos and the Rion-Patras faults being located very close to the city of Patras. We processed ascending and descending acquisitions of ASAR/ENVISAT in the period between 2002-2010, to produce Persistent Scatterers and Small Baseline Subsets deformation rates maps. We have combined and constrained them with a number of GPS observations in order to extract the precise Up-Down and East-West deformation components. We verified the results and compared them with other independent studies. We present and discuss the deformation rates along cross sections inside the city of Patras, around the Rion-Antirion Bridge, around the areas or creeping faulting and river deltas. Significant complex ground deformations are observed and interpreted. The Aigion fault seems very active with uplift rate of about 2mm/yr. The Movri, 2008 and Efpalio, 2010, seismic events are modeled, constrained by the seismic, the GPS and the SAR interferometry data. The studied tectonic features are pieces of a diffused triple junction at the junction of the Corinth rift and the northwestern termination of the Hellenic arc, which are investigated and discussed. This research is performed as part of the ANR-SISCOR project in close connection to the CRL working group and with the support of CNRS-INSU.

  8. Vibration modulated subaperture stitching interferometry.

    PubMed

    Liang, Chao-Wen; Chang, Hung-Sheng; Lin, Po-Chih; Lee, Cheng-Chung; Chen, Yi-Chun

    2013-07-29

    A novel subaperture stitching interferometry is developed to measure the surface deformation of the lens by utilizing the mechanical vibration induced from a motorized stage. The interferograms of different subapertures are acquired on the fly while the tested optics is rotating against its symmetrical axis. The measurement throughput and the subaperture positioning accuracy are improved simultaneously by adopting both the synchronous rotational scanning mechanism and the non-uniform phase shifting algorithm. The experimental measurement shows the stitched phase RMS error of 0.0037 waves proving the feasibility of the proposed phase acquisition method. PMID:23938696

  9. Holograph and Interferometry.

    ERIC Educational Resources Information Center

    Altman, Thomas C.

    1992-01-01

    Describes a method to create holograms for use in different interferometry techniques. Students utilize these techniques in experiments to study the structural integrity of a clarinet reed and the effects of temperature on objects. (MDH)

  10. PALSAR SCANSAR SCANSAR Interferometry

    NASA Astrophysics Data System (ADS)

    Shimada, Masanobu

    2008-11-01

    We have examined the capability of the PALSAR SCANSAR SCANSAR interferometry by observing the African forest and Sahara desert, both of which are separated 46 days in March and April of 2008. These two paths are well tuned for the orbital tube of 200m and the beam synchronization of the transmission positions in 200m to 500m, we have succeeded the PALSAR SCANSAR SCANSAR interferometry and achieved the detection of the height information. We will report the results in this paper.

  11. Identified particle production, azimuthal anisotropy, and interferometry measurements in Au+Au collisions at sq root(s{sub NN})=9.2 GeV

    SciTech Connect

    Abelev, B. I.; Barannikova, O.; Betts, R. R.; Garcia-Solis, E. J.; Hofman, D. J.; Hollis, R. S.; Iordanova, A.; Kauder, K.; Suarez, M. C.; Aggarwal, M. M.; Bhati, A. K.; Kumar, L.; Pruthi, N. K.; Ahammed, Z.; Chattopadhyay, S.; Mazumdar, M. R. Dutta; Ganti, M. S.; Ghosh, P.; Mohanty, B.; Nayak, T. K.

    2010-02-15

    We present the first measurements of identified hadron production, azimuthal anisotropy, and pion interferometry from Au+Au collisions below the nominal injection energy at the BNL Relativistic Heavy-Ion Collider (RHIC) facility. The data were collected using the large acceptance solenoidal tracker at RHIC (STAR) detector at sq root(s{sub NN})=9.2 GeV from a test run of the collider in the year 2008. Midrapidity results on multiplicity density dN/dy in rapidity y, average transverse momentum , particle ratios, elliptic flow, and Hanbury-Brown-Twiss (HBT) radii are consistent with the corresponding results at similar sq root(s{sub NN}) from fixed-target experiments. Directed flow measurements are presented for both midrapidity and forward-rapidity regions. Furthermore the collision centrality dependence of identified particle dN/dy, , and particle ratios are discussed. These results also demonstrate that the capabilities of the STAR detector, although optimized for sq root(s{sub NN})=200 GeV, are suitable for the proposed QCD critical-point search and exploration of the QCD phase diagram at RHIC.

  12. Apparatus and method for quantitative measurement of small differences in optical absorptivity between two samples using differential interferometry and the thermooptic effect

    DOEpatents

    Cremers, D.A.; Keller, R.A.

    1982-06-08

    An apparatus and method for the measurement of small differences in optical absorptivity of weakly absorbing solutions using differential interferometry and the thermooptic effect has been developed. Two sample cells are placed in each arm of an interferometer and are traversed by colinear probe and heating laser beams. The interrogation probe beams are recombined forming a fringe pattern, the intensity of which can be related to changes in optical pathlength of these laser beams through the cells. This in turn can be related to small differences in optical absorptivity which results in different amounts of sample heating when the heating laser beams are turned on, by the fact that the index of refraction of a liquid is temperature dependent. A critical feature of this invention is the stabilization of the optical path of the probe beams against drift. Background (solvent) absorption can then be suppressed by a factor of approximately 400. Solute absorptivities of about 10/sup -5/ cm/sup -1/ can then be determined in the presence of background absorptions in excess of 10/sup -3/ cm/sup -1/. In addition, the smallest absorption measured with the instant apparatus and method is about 5 x 10/sup -6/ cm/sup -1/.

  13. Apparatus and method for quantitative measurement of small differences in optical absorptivity between two samples using differential interferometry and the thermooptic effect

    DOEpatents

    Cremers, D.A.; Keller, R.A.

    1984-05-08

    An apparatus and method for the measurement of small differences in optical absorptivity of weakly absorbing solutions using differential interferometry and the thermooptic effect have been developed. Two sample cells are placed in each arm of an interferometer and are traversed by colinear probe and heating laser beams. The interrogation probe beams are recombined forming a fringe pattern, the intensity of which can be related to changes in optical path length of these laser beams through the cells. This in turn can be related to small differences in optical absorptivity which results in different amounts of sample heating when the heating laser beams are turned on, by the fact that the index of refraction of a liquid is temperature dependent. A critical feature of this invention is the stabilization of the optical path of the probe beams against drift. Background (solvent) absorption can then be suppressed by a factor of approximately 400. Solute absorptivities of about 10[sup [minus]5] cm[sup [minus]1] can then be determined in the presence of background absorptions in excess of 10[sup [minus]3] cm[sup [minus]1]. In addition, the smallest absorption measured with the instant apparatus and method is about 5 [times] 10[sup [minus]6] cm[sup [minus]1]. 6 figs.

  14. Apparatus and method for quantitative measurement of small differences in optical absorptivity between two samples using differential interferometry and the thermooptic effect

    DOEpatents

    Cremers, David A.; Keller, Richard A.

    1984-01-01

    An apparatus and method for the measurement of small differences in optical absorptivity of weakly absorbing solutions using differential interferometry and the thermooptic effect has been developed. Two sample cells are placed in each arm of an interferometer and are traversed by colinear probe and heating laser beams. The interrogation probe beams are recombined forming a fringe pattern, the intensity of which can be related to changes in optical pathlength of these laser beams through the cells. This in turn can be related to small differences in optical absorptivity which results in different amounts of sample heating when the heating laser beams are turned on, by the fact that the index of refraction of a liquid is temperature dependent. A critical feature of this invention is the stabilization of the optical path of the probe beams against drift. Background (solvent) absorption can then be suppressed by a factor of approximately 400. Solute absorptivities of about 10.sup.-5 cm.sup.-1 can then be determined in the presence of background absorptions in excess of 10.sup.-3 cm.sup.-1. In addition, the smallest absorption measured with the instant apparatus and method is about 5.times. 10.sup.-6 cm.sup.-1.

  15. Beam-energy-dependent two-pion interferometry and the freeze-out eccentricity of pions measured in heavy ion collisions at the STAR detector

    SciTech Connect

    Adamczyk, L.

    2015-07-10

    In this study, we present results of analyses of two-pion interferometry in Au+Au collisions at √sNN = 7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV measured in the STAR detector as part of the RHIC Beam Energy Scan program. The extracted correlation lengths (HBT radii) are studied as a function of beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass (mT) of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at kinetic freeze-out. The energy dependence of this observable is expected to be sensitive to changes in the equation of state. A new global fit method is studied as an alternate method to directly measure the parameters in the azimuthal analysis. The eccentricity shows a monotonic decrease with beam energy that is qualitatively consistent with the trend from all model predictions and quantitatively consistent with a hadronic transport model.

  16. Beam-energy-dependent two-pion interferometry and the freeze-out eccentricity of pions measured in heavy ion collisions at the STAR detector

    DOE PAGESBeta

    Adamczyk, L.

    2015-07-10

    In this study, we present results of analyses of two-pion interferometry in Au+Au collisions at √sNN = 7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV measured in the STAR detector as part of the RHIC Beam Energy Scan program. The extracted correlation lengths (HBT radii) are studied as a function of beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass (mT) of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at kinetic freeze-out. The energy dependence of this observable is expected to be sensitive to changes in the equationmore » of state. A new global fit method is studied as an alternate method to directly measure the parameters in the azimuthal analysis. The eccentricity shows a monotonic decrease with beam energy that is qualitatively consistent with the trend from all model predictions and quantitatively consistent with a hadronic transport model.« less

  17. Beam-energy-dependent two-pion interferometry and the freeze-out eccentricity of pions measured in heavy ion collisions at the STAR detector

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Beavis, D. R.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chwastowski, J.; Codrington, M. J. M.; Contin, G.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Dilks, C.; Ding, F.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Engle, K. S.; Eppley, G.; Eun, L.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Gliske, S.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Kosarzewski, L. K.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Olvitt, D. L.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Sun, X.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szelezniak, M. A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yan, W.; Yang, C.; Yang, Y.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zawisza, Y.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, J. L.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2015-07-01

    We present results of analyses of two-pion interferometry in Au +Au collisions at √{sNN}=7.7 , 11.5, 19.6, 27, 39, 62.4, and 200 GeV measured in the STAR detector as part of the BNL Relativistic Heavy Ion Collider Beam Energy Scan program. The extracted correlation lengths (Hanbury-Brown-Twiss radii) are studied as a function of beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass (mT) of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at kinetic freeze-out. The energy dependence of this observable is expected to be sensitive to changes in the equation of state. A new global fit method is studied as an alternate method to directly measure the parameters in the azimuthal analysis. The eccentricity shows a monotonic decrease with beam energy that is qualitatively consistent with the trend from all model predictions and quantitatively consistent with a hadronic transport model.

  18. Pressure and Temperature Dependence of the Elasticity of Pyrope-Majorite [Py60Mj40 and Py50Mj50] Garnets Solid Solution Measured by Ultrasonic Interferometry Technique

    SciTech Connect

    Gwanmesia, G.; Wang, L; Tripletta, R; Liebermann, R

    2009-01-01

    Compressional (P) and shear (S) wave velocities have been measured for two synthetic polycrystalline specimens of pyrope-majorite garnets [Py60Mj40 and Py50Mj50] by ultrasonic interferometry to 8 GPa and 1000 K, in a DIA-type cubic anvil high pressure apparatus (SAM-85) interfaced with synchrotron X-radiation and X-ray imaging. Elastic bulk (KS) and shear (G) moduli data obtained at the end of the cooling cycles were fitted to functions of Eulerian strain to third order yielding pressure derivatives of the elastic moduli (?KS/?P)T = 4.3 (3); (?G/?P)T = 1.5 (1) for Py60Mj40 garnet and (?KS/?P)T = 4.4 (1); (?G/?P)T = 1.3 (1) for Py50Mj40 garnet. Both (?KS/?P)T and (?G/?P)T are identical for the two garnet compositions and are also consistent with Brillouin scattering data for polycrystalline Py50Mj50. Moreover, the new pressure derivatives of the elastic moduli are equal within experimental uncertainties to those of end-member pyrope garnet from ultrasonic studies.

  19. Ground motion measurement in the Lake Mead area, Nevada, by differential synthetic aperture radar interferometry time series analysis: Probing the lithosphere rheological structure

    NASA Astrophysics Data System (ADS)

    Cavalié, O.; Doin, M.-P.; Lasserre, C.; Briole, P.

    2007-03-01

    We measure ground motion around the Lake Mead, Nevada, using synthetic aperture radar interferometry. The lake water level has fluctuated through time since impoundment in 1935. To quantify the deformation due to water level variations over the past decade, and to constrain the crust and mantle rheological parameters in the lake area, we analyze 241 interferograms based on 43 ERS images acquired between 1992 and 2002. All interferograms have a high coherence due to arid conditions. Most of them show strong atmospheric artefacts. Tropospheric phase delays are estimated and corrected for each interferogram by analyzing the phase/elevation correlation. Corrections are validated using data from the ERA40 global atmospheric reanalysis. Corrected interferograms are inverted pixel by pixel to solve for the time series of ground motion in the lake area. Temporal smoothing is added to reduce random atmospheric artefacts. The observed deformation is nonlinear in time and spreads over a 50 × 50 km2 area. We observe a 16 mm subsidence between 1995 and 1998 due to an 11 m water level increase, followed by an uplift due to the water level drop after 2000. We model the deformation, taking into account the loading history of the lake since 1935. A simple elastic model with parameters constrained by seismic wave velocities does not explain the amplitude of the observed motion. The two-layer viscoelastic model proposed by Kaufmann and Amelung (2000), with a mantle viscosity of 1018 Pa s, adjusts well the data amplitude and its spatiotemporal shape.

  20. Optical intensity interferometry through atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Tan, P. K.; Chan, A. H.; Kurtsiefer, C.

    2016-04-01

    Conventional ground-based astronomical observations suffer from image distortion due to atmospheric turbulence. This can be minimized by choosing suitable geographic locations or adaptive optical techniques, and avoided altogether by using orbital platforms outside the atmosphere. One of the promises of optical intensity interferometry is its independence from atmospherically induced phase fluctuations. By performing narrow-band spectral filtering on sunlight and conducting temporal intensity interferometry using actively quenched avalanche photodiodes, the Solar g(2)(τ) signature was directly measured. We observe an averaged photon bunching signal of g(2)(τ) = 1.693 ± 0.003 from the Sun, consistently throughout the day despite fluctuating weather conditions, cloud cover and elevation angle. This demonstrates the robustness of the intensity interferometry technique against atmospheric turbulence and opto-mechanical instabilities, and the feasibility to implement measurement schemes with both large baselines and long integration times.

  1. Preview of Blackbeard interferometry

    SciTech Connect

    Carter, M.J.

    1992-09-01

    Blackbeard is a broadband VHF measurements satellite experiment designed and built by the Space Science and Technology division of the Los Alamos National Laboratory. Blackbeard is a piggy-back experiment on the ALEXIS satellite to be launched into a 70 degree inclination orbit at an altitude of 750 km. The satellite experimental operation and data retrieval are controlled through a telemetry link from the Satellite Operations Center (SOC) located at Los Alamos, NM. The primary experimental objectives of Blackbeard are three-fold: (1) Study the dispersion of broad-band impulsive electromagnetic signals -- in particular, the higher-order amplitude and phase distortion due to propagation through the ionosphere. These depend on ionospheric conditions and irregularities. (2) Utilize RF interferometry and scintillation techniques in the low VHF-band to determine the size and extent of ionospheric irregularities and wave structure -- both natural and artificially induced. This narrow-band data will be used to categorize the ionospheric media as undisturbed, oscillatory, or turbulent. These parameters will then be input into transfer function simulations for broad-band propagation and compared with broad-band propagation data from Blackbeard. (3) Survey and characterize background noise in the VHF-band-consisting of (1) cataloging broadcast amplitudes and signatures and mapping their global pattern, and (2) cataloging the signatures of lightning events. Also, correlate emissions in the visible and VHF bands in an attempt to confirm broad-band RF emissions assumed to be associated with lightning.

  2. Preview of Blackbeard interferometry

    SciTech Connect

    Carter, M.J.

    1992-01-01

    Blackbeard is a broadband VHF measurements satellite experiment designed and built by the Space Science and Technology division of the Los Alamos National Laboratory. Blackbeard is a piggy-back experiment on the ALEXIS satellite to be launched into a 70 degree inclination orbit at an altitude of 750 km. The satellite experimental operation and data retrieval are controlled through a telemetry link from the Satellite Operations Center (SOC) located at Los Alamos, NM. The primary experimental objectives of Blackbeard are three-fold: (1) Study the dispersion of broad-band impulsive electromagnetic signals -- in particular, the higher-order amplitude and phase distortion due to propagation through the ionosphere. These depend on ionospheric conditions and irregularities. (2) Utilize RF interferometry and scintillation techniques in the low VHF-band to determine the size and extent of ionospheric irregularities and wave structure -- both natural and artificially induced. This narrow-band data will be used to categorize the ionospheric media as undisturbed, oscillatory, or turbulent. These parameters will then be input into transfer function simulations for broad-band propagation and compared with broad-band propagation data from Blackbeard. (3) Survey and characterize background noise in the VHF-band-consisting of (1) cataloging broadcast amplitudes and signatures and mapping their global pattern, and (2) cataloging the signatures of lightning events. Also, correlate emissions in the visible and VHF bands in an attempt to confirm broad-band RF emissions assumed to be associated with lightning.

  3. Measurement of Along-track Displacements due to the M6.0 August 24, 2014 South Napa Earthquake Using X-band Multiple-Aperture SAR Interferometry

    NASA Astrophysics Data System (ADS)

    Jung, H. S.; Jo, M. J.; Yun, S. H.; Jung, H. I.; Koh, Y. C.; Webb, F.

    2014-12-01

    Multiple-aperture SAR interferometry (MAI) has been developed for measuring surface displacements in along-track direction as an alternative method of amplitude offset tracking method. Various studies on geological phenomena have been carried out using MAI technique with C-band and L-band SAR data, but application of MAI to X-band SAR is challenging due to its more severe temporal decorrelation compared to longer wavelength radar. The Italian Space Agency's (ASI) COSMO-SkyMed (CSK) mission consisting of four identical radar satellites has a powerful capability to minimize temporal baselines maintaining high coherence. This offers a good chance for MAI application for precise measurement of along-track displacements. In this study, we demonstrate the MAI performance of X-band SAR for the M6.0, South Napa Earthquake occurred on August 24, 2014. A coseismic CSK pair data (July 26 and August 27, 2014) acquired from descending orbit was used to show the along-track displacements in the fault zone. In order to evaluate the precision for measuring MAI deformation on the Napa Earthquake using CSK data, we produced a coherence map of the interferogram because the MAI precision is a function of interferometric coherence. However, we found that standard deviation of MAI phase does not coincide with the theoretical variation. The measurement uncertainty of along-track displacements was estimated by using the predefined empirical equation which was established through the performance test using multi-path CSK dataset at Kilauea Volcano region. The uncertainty map of the along-track displacements in the South Napa Earthquake region provides a reliable metric to estimate the variance/covariance of the data, useful for 3-D displacement field construction and geophysical modeling.

  4. Virtual Reference Interferometry: Theory & Experiment

    NASA Astrophysics Data System (ADS)

    Galle, Michael Anthony

    This thesis introduces the idea that a simulated interferogram can be used as a reference for an interferometer. This new concept represents a paradigm shift from the conventional thinking, where a reference is the phase of a wavefront that traverses a known path. The simulated interferogram used as a reference is called a virtual reference. This thesis develops the theory of virtual reference interferometry and uses it for the characterization of chromatic dispersion in short length (<1m) fibers and optical components. Characterization of chromatic dispersion on short length fiber and optical components is a very difficult challenge. Accurate measurement of first and second order dispersion is important for applications from optical component design to nonlinear photonics, sensing and communications. Techniques for short-length dispersion characterization are therefore critical to the development of many photonic systems. The current generation of short-length dispersion measurement techniques are either easy to operate but lack sufficient accuracy, or have sufficient accuracy but are difficult to operate. The use of a virtual reference combines the advantages of these techniques so that it is both accurate and easy to operate. Chromatic dispersion measurements based on virtual reference interferometry have similar accuracy as the best conventional measurement techniques due to the ability to measure first and second order dispersion directly from the interference pattern. Unique capabilities of virtual reference interferometry are demonstrated, followed by a derivation of the operational constraints and system parameters. The technique is also applied to the characterization of few-mode fibers, a hot topic in telecommunications research where mode division multiplexing promises to expand network bandwidth. Also introduced is the theory of dispersive virtual reference interferometry, which can be used to overcome the bandwidth limitations associated with the

  5. Coarse frequency comb interferometry

    NASA Astrophysics Data System (ADS)

    Schwider, J.

    2008-08-01

    Real wedge interferometers of the Fizeau-type do not allow for fringes in case of a spectral broad band source - or in short: for white light fringes. Here, the use of a suitable frequency comb source will help to overcome this limitation on the one hand and on the other will offer the capability for enhanced phase sensitivity in high precision measurements of surface deviations. Frequency combs can be produced either by using a pulse train from a fs-laser or by passive filtering of the light emitted by a broad band source as a superlum-diode or a fs-laser. The frequency comb produced by a common fs-laser is extremely fine, i.e., the frequency difference of consecutive peaks is very small or the distance of consecutive pulses of the pulse train might be of the order of 1m. Therefore, the coarse pulse train produced by passive filtering of a broad band source is better adapted to the needs of surface testing interferometers. White light fringes are either applied for the profiling of discontinuous surfaces and/or can serve as an indication for the correct choice of multiplication factors in superposition interferometry. During the last decennium it became more and more clear that spatially incoherent sources provide better measuring accuracy in surface measurements due to the reduced influence of dust diffraction patterns. The advantage of laser illumination can nevertheless be maintained if the laser light is made spatially incoherent through moving scatterers in the light path. Here, we will discuss the application of spatially incoherent broad band light frequency filtered through a Fabry-Perot filter. The main applications are in the following fields: (1) surface profiling applications using two-beam Fizeau interferometers, (2) selection of single cavities out of a series of interlaced cavities, and (3) sensitivity enhancement for multi-beam interferometers for planeness or sphericity measurements. Some of the discussed possibilities will be experimentally

  6. Measurements of mid-latitude E-region, sporadic-E, and TID-related drifts using HF Doppler-sorted interferometry

    NASA Astrophysics Data System (ADS)

    Parkinson, M. L.; Dyson, P. L.

    1998-03-01

    Modern HF digital ionosondes have been used for Doppler-sorted interferometry (DSI) to automatically measure F-region plasma drifts by detecting the Doppler shift and angle-of-arrival of echoes. We report on the use of a Digisonde 256 receiving on a seven-element antenna array located at the Australian mid-latitude station Beveridge (37.5° S, 144.9° E, -48.0°CGM latitude) to extend the routine application of drift measurements to the E-region, and especially sporadic-E (Es). Obtaining good quality E-region drift measurements required many more soundings independent in the frequency and time domains than are usually made for F-region measurements. This is because the E-region isoionic surfaces were usually more horizontally stratified than those in the more disturbed F-region, and so did not return as many of the oblique echoes upon which the accuracy of the technique depends. Smoothness of the ionosphere was less of a problem when performing Es measurements because of the patchy, cloud-like property of the layers. When making F-region drift measurements the motions are usually thought of as being uniform throughout the volume of ionosphere sampled for echoes. Application of the technique to E-region measurements is interesting because of the enhanced irregular neutral winds associated with gravity waves which grow in amplitude with height. These irregular winds control the motion of the plasma via high collision frequencies, and lead to the formation of Es layers at mid-latitudes. Therefore, the possibility of sharp vertical gradients in plasma drifts must be considered when making and analysing measurements. During numerous campaigns conducted throughout 1994/95, horizontal drifts in the range of ≈ 30-250 m/s were measured for Es patches lasting up to 6 h. The drift measurements sometimes indicated the presence of wave-like motions in the ionosphere with periods in the range 5-90 min. A TID was observed to propagate towards the station from the south, and

  7. Interferometry with synthetic gauge fields

    SciTech Connect

    Anderson, Brandon M.; Taylor, Jacob M.; Galitski, Victor M.

    2011-03-15

    We propose a compact atom interferometry scheme for measuring weak, time-dependent accelerations. Our proposal uses an ensemble of dilute trapped bosons with two internal states that couple to a synthetic gauge field with opposite charges. The trapped gauge field couples spin to momentum to allow time-dependent accelerations to be continuously imparted on the internal states. We generalize this system to reduce noise and estimate the sensitivity of such a system to be S{approx}10{sup -7}(m/s{sup 2}/{radical}(Hz)).

  8. An Interferometry Imaging Beauty Contest

    NASA Technical Reports Server (NTRS)

    Lawson, Peter R.; Cotton, William D.; Hummel, Christian A.; Monnier, John D.; Zhaod, Ming; Young, John S.; Thorsteinsson, Hrobjartur; Meimon, Serge C.; Mugnier, Laurent; LeBesnerais, Guy; Thiebaut, Eric; Tuthill, Peter G.; Hani, Christopher A.; Pauls, Thomas; DuvertI, Gilles; Garcia, Paulo; Kuchner, Marc

    2004-01-01

    We present a formal comparison of the performance of algorithms used for synthesis imaging with optical/infrared long-baseline interferometers. Six different algorithms are evaluated based on their performance with simulated test data. Each set of test data is formated in the interferometry Data Exchange Standard and is designed to simulate a specific problem relevant to long-baseline imaging. The data are calibrated power spectra and bispectra measured with a ctitious array, intended to be typical of existing imaging interferometers. The strengths and limitations of each algorithm are discussed.

  9. Advances in Small-Telescope Speckle Interferometry

    NASA Astrophysics Data System (ADS)

    Rowe, David J.

    2016-06-01

    The current revolution in CMOS camera technology has enabled a new generation of small telescope systems targeted at the measurement of close binary systems using the techniques of speckle interferometry and bispectrum analysis. These inexpensive, ultra-sensitive, high resolution cameras are now outperforming CCD technology, and come at a truly affordable price. In addition, dedicated, user-friendly speckle interferometry reduction software has been developed for the amateur, making it easy to perform the otherwise complicated data processing tasks. This talk will address these recent advances in hardware and software, and describe some of the results of the informal amateur-professional collaboration that has formed around them.

  10. New method for measuring the thickness and shape of a thin film simultaneously by combining interferometry and laser triangulation

    NASA Astrophysics Data System (ADS)

    Zeng, LiJiang; Ohnuki, Takeshi; Matsumoto, Hirokazu; Kawachi, Keiji

    1996-07-01

    A new method has been developed to simultaneously measure the thickness and shape of a thin film, such as a dragonfly wing. The innovation in the method is the combining of a heterodyne interferometer and a laser triangulation displacement sensor into one optical system. We confirmed the accuracy of the method by measuring the displacement of a glass plate and the thickness variation generated by a rotated glass plate. The system has a relative accuracy of 1% in the shape measurement and 1.3% in the thickness variation measurement. The method was then applied to a dragonfly wing. The results indicated that the method is very effective in biomechanics studies, such as evaluating the flight performance of dragonflies. In such evaluations, it is essential to measure the high accuracy the variations in both shape and thickness of the wing simultaneously.

  11. MARBLE (Multiple Antenna Radio-interferometry for Baseline Length Evaluation): Development of a Compact VLBI System for Calibrating GNSS and Electronic Distance Measurement Devices

    NASA Astrophysics Data System (ADS)

    Ichikawa, R.; Ishii, A.; Takiguchi, H.; Kimura, M.; Sekido, M.; Takefuji, K.; Ujihara, H.; Hanado, Y.; Koyama, Y.; Kondo, T.; Kurihara, S.; Kokado, K.; Kawabata, R.; Nozawa, K.; Mukai, Y.; Kuroda, J.; Ishihara, M.; Matsuzaka, S.

    2012-12-01

    We are developing a compact VLBI system with a 1.6-m diameter aperture dish in order to provide reference baseline lengths for calibration. The reference baselines are used to validate surveying instruments such as GPS and EDM and is maintained by the Geospatial Information Authority of Japan (GSI). The compact VLBI system will be installed at both ends of the reference baseline. Since the system is not sensitive enough to detect fringes between the two small dishes, we have designed a new observation concept including one large dish station. We can detect two group delays between each compact VLBI system and the large dish station based on conventional VLBI measurement. A group delay between the two compact dishes can be indirectly calculated using a simple equation. We named the idea "Multiple Antenna Radio-interferometry for Baseline Length Evaluation", or MARBLE system. The compact VLBI system is easy transportable and consists of the compact dish, a new wide-band front-end system, azimuth and elevation drive units, an IF down-converter unit, an antenna control unit (ACU), a counterweight, and a monument pillar. Each drive unit is equipped with a zero-backlash harmonic drive gearing component. A monument pillar is designed to mount typical geodetic GNSS antennas easily and an offset between the GNSS antenna reference point. The location of the azimuth-elevation crossing point of the VLBI system is precisely determined with an uncertainty of less than 0.2 mm. We have carried out seven geodetic VLBI experiments on the Kashima-Tsukuba baseline (about 54 km) using the two prototypes of the compact VLBI system between December 2009 and December 2010. The average baseline length and repeatability of the experiments is 54184874.0 ± 2.4 mm. The results are well consistent with those obtained by GPS measurements. In addition, we are now planning to use the compact VLBI system for precise time and frequency comparison between separated locations.

  12. VERY LONG BASELINE INTERFEROMETRY MEASURED PROPER MOTION AND PARALLAX OF THE γ-RAY MILLISECOND PULSAR PSR J0218+4232

    SciTech Connect

    Du, Yuanjie; Chen, Ding; Yang, Jun; Campbell, Robert M.; Janssen, Gemma; Stappers, Ben

    2014-02-20

    PSR J0218+4232 is a millisecond pulsar (MSP) with a flux density ∼0.9 mJy at 1.4 GHz. It is very bright in the high-energy X-ray and γ-ray domains. We conducted an astrometric program using the European VLBI Network (EVN) at 1.6 GHz to measure its proper motion and parallax. A model-independent distance would also help constrain its γ-ray luminosity. We achieved a detection of signal-to-noise ratio S/N >37 for the weak pulsar in all five epochs. Using an extragalactic radio source lying 20 arcmin away from the pulsar, we estimate the pulsar's proper motion to be μ{sub α}cos δ = 5.35 ± 0.05 mas yr{sup –1} and μ{sub δ} = –3.74 ± 0.12 mas yr{sup –1}, and a parallax of π = 0.16 ± 0.09 mas. The very long baseline interferometry (VLBI) proper motion has significantly improved upon the estimates from long-term pulsar timing observations. The VLBI parallax provides the first model-independent distance constraints: d=6.3{sub −2.3}{sup +8.0} kpc, with a corresponding 3σ lower-limit of d = 2.3 kpc. This is the first pulsar trigonometric parallax measurement based solely on EVN observations. Using the derived distance, we believe that PSR J0218+4232 is the most energetic γ-ray MSP known to date. The luminosity based on even our 3σ lower-limit distance is high enough to pose challenges to the conventional outer gap and slot gap models.

  13. Interferometry science center

    NASA Technical Reports Server (NTRS)

    Sargent, A. I.

    2002-01-01

    The Interferometry Science Center (ISC) is operated jointly by Caltech and JPL and is part of NASA's Navigator Program. The ISC has been created to facilitate the timely and successful execution of scientific investigations within the Navigator program, particularly those that rely on observations from NASA's interferometer projects. Currently, ISC is expected to provide full life cycle support for the Keck Interferometer, the Starlight mission, the Space Interferometry Mission, and the Terrestrial Planet Finder Mission. The nature and goals of ISc will be described.

  14. New experimental method to measure pure and cross diffusion coefficients of transparent ternary mixtures using Mach-Zehnder interferometry

    NASA Astrophysics Data System (ADS)

    Ahadi, Amirhossein; Saghir, M. Ziad

    2014-08-01

    In this study, a Mach-Zehnder interferometer that is equipped with two lasers of different wavelengths was used to conduct high resolution measurements of concentration profiles of a ternary mixture inside a diffusion cell. Windowed Fourier transform along with an advanced unwrapping procedure was employed to extract the phase image from fringe images. Then the phase difference was obtained for a spatial resolution of 1920×1240. According to the measured refractive index profile, concentration contours of two components (out of three) were measured. Consequently, the concentration profile of the third components was calculated. Previously, the analytical solution for binary mixtures was used to estimate only the pure diffusion coefficients. In this study, for the first time, the refractive indices measured by two lasers along with the analytical solution for the ternary system, based on Fick's law, and an evolutionary algorithm (EA) known as a genetic algorithm (GA) were employed to measure the pure and cross diffusion coefficients of a transparent ternary mixture simultaneously. The optimization method to estimate diffusion coefficients was tested against various objective functions, and the best approach was that which was proposed herein. In order to validate the proposed measurement method, the experimental results of the Selectable Optical Diagnostics Instrument-Diffusion Coefficients in Mixtures (SODI-DCMIX1 project) on board the International Space Station (ISS) were analyzed using this technique and the obtained results were compared with previous techniques.

  15. Multiple Beam Interferometry in Elementary Teaching

    ERIC Educational Resources Information Center

    Tolansky, S.

    1970-01-01

    Discusses a relatively simple technique for demonstrating multiple beam interferometry. The technique can be applied to measuring (1) radii of curvature of lenses, (2) surface finish of glass, and (3) differential phase change on reflection. Microtopographies, modulated fringe systems and opaque objects may also be observed by this technique.…

  16. Group-velocity dispersion in multimode photonic crystal fibers measured using time-domain white-light interferometry

    NASA Astrophysics Data System (ADS)

    Böswetter, Pascal; Baselt, Tobias; Ebert, Frank; Basan, Fabiola; Hartmann, Peter

    2011-02-01

    Optical fibers are used in various applications, e. g. optical communication, material processing, as a laser medium or to generate efficient supercontinua. For most of these applications the knowledge of the dispersion is an essential prerequisite. The dispersion and modal properties of photonic crystal fibers (PCF) strongly depend on the hole diameter and pitch. Since fabrication tolerances affect the structure of the photonic lattice, the dispersion behavior as well as the number of guided transverse modes can differ from numerical calculations. Dispersion measurement of singlemode photonic crystal fibers has been well described in recent papers. However, the determination of dispersion in the presence of higher-order modes is much more difficult. To measure the dispersion of optical fibers with high accuracy, a time-domain white-light interferometer based on a Mach-Zehnder interferometer is presented. The experimental setup allows to determine the wavelength-dependent differential group delay of light travelling through conventional fibers and PCFs within the wavelength range from VIS to NIR. Interferences appear due to superposition of two laser beams, one propagating through the tested fiber and the other travelling through air. Measuring the different group delays of a step-index fiber shows the sufficient accuracy of the interferometer. This paper demonstrates a simple yet effective way to suppress higher-order modes, making it possible to measure the chromatic dispersion of singlemode as well as multimode fibers.

  17. Techniques in Broadband Interferometry

    SciTech Connect

    Erskine, D J

    2004-01-04

    This is a compilation of my patents issued from 1997 to 2002, generally describing interferometer techniques that modify the coherence properties of broad-bandwidth light and other waves, with applications to Doppler velocimetry, range finding, imaging and spectroscopy. Patents are tedious to read in their original form. In an effort to improve their readability I have embedded the Figures throughout the manuscript, put the Figure captions underneath the Figures, and added section headings. Otherwise I have resisted the temptation to modify the words, though I found many places which could use healthy editing. There may be minor differences with the official versions issued by the US Patent and Trademark Office, particularly in the claims sections. In my shock physics work I measured the velocities of targets impacted by flyer plates by illuminating them with laser light and analyzing the reflected light with an interferometer. Small wavelength changes caused by the target motion (Doppler effect) were converted into fringe shifts by the interferometer. Lasers having long coherence lengths were required for the illumination. While lasers are certainly bright sources, and their collimated beams are convenient to work with, they are expensive. Particularly if one needs to illuminate a wide surface area, then large amounts of power are needed. Orders of magnitude more power per dollar can be obtained from a simple flashlamp, or for that matter, a 50 cent light bulb. Yet these inexpensive sources cannot practically be used for Doppler velocimetry because their coherence length is extremely short, i.e. their bandwidth is much too wide. Hence the motivation for patents 1 & 2 is a method (White Light Velocimetry) for allowing use of these powerful but incoherent lamps for interferometry. The coherence of the illumination is modified by passing it through a preparatory interferometer.

  18. Calibration and imaging algorithms for full-Stokes optical interferometry

    NASA Astrophysics Data System (ADS)

    Elias, Nicholas M.; Mozurkewich, David; Schmidt, Luke M.; Jurgenson, Colby A.; Edel, Stanislav S.; Jones, Carol E.; Halonen, Robert J.; Schmitt, Henrique R.; Jorgensen, Anders M.; Hutter, Donald J.

    2012-07-01

    Optical interferometry and polarimetry have separately provided new insights into stellar astronomy, especially in the fields of fundamental parameters and atmospheric models. Optical interferometers will eventually add full-Stokes polarization measuring capabilities, thus combining both techniques. In this paper, we: 1) list the observables, calibration quantities, and data acquisition strategies for both limited and full optical interferometric polarimetry (OIP); 2) describe the masking interferometer AMASING and its polarization measuring enhancement called AMASING-POL; 3) show how a radio interferometry imaging package, CASA, can be used for optical interferometry data reduction; and 4) present imaging simulations for Be stars.

  19. Measuring Variable Scales of Surface Deformation in and around the Yellowstone Caldera with TerraSAR-X Interferometry

    NASA Astrophysics Data System (ADS)

    Wicks, C. W., Jr.; Dzurisin, D.

    2014-12-01

    Utilizing three years of TerraSAR-X (TSX) Stripmap data covering the Yellowstone Caldera, Wyoming, we identify several examples showing the benefits of the high spatial and temporal resolution TSX data. Although the Stripmap footprints are small, compared to those of past SAR satellites, we are nonetheless able to track subsidence/uplift cycles of the ~50 x 80 km Yellowstone caldera using multiple strips. The Stripmap data are also useful for measuring deformation associated with the area of the North Rim anomaly, an area of repeated uplift and subsidence, ~30 km in diameter near the intersection of the north caldera rim, north-trending Mammoth-Norris Corridor, and west-northwest trending seismic belt east of Hebgen Lake. We measured ~45 mm of uplift associated with an episode that occurred mostly during the winter of 2013-2014 (as verified by GPS), and ~15 mm of subsequent subsidence in the early summer of 2014. The TSX Stripmap data have also proven effective at measuring small-scale deformation features. Because of the high-resolution of the TSX Stripmap data, we have also been able to measure many small-scale deforming features in Yellowstone National Park that are associated with apparent aquifer discharge/recharge cycles, unstable slope movement, geyser basin deformation, and deformation related to other hydrothermal features. We present an example of ~3 cm of seasonal deformation likely resulting from water movement in and out of an aquifer along the southwest caldera rim. We also document subsidence of ~1 cm/yr in a circular area nearly 0.5 km across near the vent from the Pitchstone Plateau, a thick rhyolite flow that erupted nearly 70 ka. TSX data are instrumental in identifying the seasonal variation found in some of these features, and in measuring the small spatial areas of deformation associated with other features.

  20. Precision surveying using very long baseline interferometry

    NASA Technical Reports Server (NTRS)

    Ryan, J. W.; Clark, T. A.; Coates, R.; Ma, C.; Robertson, D. S.; Corey, B. E.; Counselman, C. C.; Shapiro, I. I.; Wittels, J. J.; Hinteregger, H. F.

    1977-01-01

    Radio interferometry measurements were used to measure the vector baselines between large microwave radio antennas. A 1.24 km baseline in Massachusetts between the 36 meter Haystack Observatory antenna and the 18 meter Westford antenna of Lincoln Laboratory was measured with 5 mm repeatability in 12 separate experiments. Preliminary results from measurements of the 3,928 km baseline between the Haystack antenna and the 40 meter antenna at the Owens Valley Radio Observatory in California are presented.

  1. Absolute flatness measurements of silicon mirrors by a three-intersection method by near-infrared interferometry.

    PubMed

    Uchikoshi, Junichi; Hayashi, Yoshinori; Ajari, Noritaka; Kawai, Kentaro; Arima, Kenta; Morita, Mizuho

    2013-01-01

    Absolute flatness of three silicon plane mirrors have been measured by a three-intersection method based on the three-flat method using a near-infrared interferometer. The interferometer was constructed using a near-infrared laser diode with a 1,310-nm wavelength light where the silicon plane mirror is transparent. The height differences at the coordinate values between the absolute line profiles by the three-intersection method have been evaluated. The height differences of the three flats were 4.5 nm or less. The three-intersection method using the near-infrared interferometer was useful for measuring the absolute flatness of the silicon plane mirrors. PMID:23758916

  2. Synthetic aperture interferometry: error analysis

    SciTech Connect

    Biswas, Amiya; Coupland, Jeremy

    2010-07-10

    Synthetic aperture interferometry (SAI) is a novel way of testing aspherics and has a potential for in-process measurement of aspherics [Appl. Opt.42, 701 (2003)].APOPAI0003-693510.1364/AO.42.000701 A method to measure steep aspherics using the SAI technique has been previously reported [Appl. Opt.47, 1705 (2008)].APOPAI0003-693510.1364/AO.47.001705 Here we investigate the computation of surface form using the SAI technique in different configurations and discuss the computational errors. A two-pass measurement strategy is proposed to reduce the computational errors, and a detailed investigation is carried out to determine the effect of alignment errors on the measurement process.

  3. Spectral-domain low-coherence interferometry for phase-sensitive measurement of Faraday rotation at multiple depths

    PubMed Central

    Yeh, Yi-Jou; Black, Adam J.; Akkin, Taner

    2014-01-01

    We describe a method for differential phase measurement of Faraday rotation from multiple depth locations simultaneously. A polarization-maintaining fiber-based spectral-domain interferometer which utilizes a low-coherent light source and a single camera is developed. Light decorrelated by the orthogonal channels of the fiber is launched on a sample as two oppositely polarized circular states. These states reflect from sample surfaces and interfere with the corresponding states of the reference arm. A custom spectrometer, which is designed to simplify camera alignment, separates the orthogonal channels and records the interference related oscillations on both spectra. Inverse Fourier transform of the spectral oscillations in k-space yields complex depth profiles, whose amplitudes and phase difference are related to reflectivity and Faraday rotation within the sample, respectively. Information along a full depth profile is produced at the camera speed without performing an axial scan for a multi-surface sample. System sensitivity for the Faraday rotation measurement is 0.86 minutes of arc. Verdet constants of clear liquids and turbid media are measured at 687 nm. PMID:24217734

  4. Phase-Shifted Laser Feedback Interferometry

    NASA Technical Reports Server (NTRS)

    Ovryn, Benjie

    1999-01-01

    Phase-shifted, laser feedback interferometry is a new diagnostic tool developed at the NASA Lewis Research Center under the Advanced Technology Development (ATD) Program directed by NASA Headquarters Microgravity Research Division. It combines the principles of phase-shifting interferometry (PSI) and laser-feedback interferometry (LFI) to produce an instrument that can quantify both optical path length changes and sample reflectivity variations. In a homogenous medium, the optical path length between two points is the product of the index of refraction and the geometric distance between the two points. LFI differs from other forms of interferometry by using the laser as both the source and the phase detector. In LFI, coherent feedback of the incident light either reflected directly from a surface or reflected after transmission through a region of interest will modulate the output intensity of the laser. The combination of PSI and LFI has produced a robust instrument, based on a low-power helium-neon (HeNe) gas laser, with a high dynamic range that can be used to measure either static or oscillatory changes of the optical path length. Small changes in optical path length are limited by the fraction of a fringe that can be measured; we can measure nonoscillatory changes with a root mean square (rms) error of the wavelength/1000 without averaging.

  5. Dense Temporal and Spatial Measurement of Surface Deformation using Real-Aperture Ground-Based Radar Interferometry

    NASA Astrophysics Data System (ADS)

    Werner, C.; Wiesmann, A.; Strozzi, T.; Wegmueller, U.; Santoro, M.

    2008-12-01

    In 2007 Gamma developed a high resolution 17.2 GHz real-aperture interferometric radar capable of measuring sub-millimeter scale deformation at distances up to 8 km. This instrument can be rapidly deployed and used to perform in-situ measurements of deformation associated with landslides, glaciers, and infrastructure. The instrument utilizes a real-aperture antenna to form a narrow azimuth beam. The azimuth beam width of 0.4 degrees determines the azimuth resolution that is proportional to the distance from the radar. The elevation antenna beamwidth is 45 degrees. The radar scans the area of interest by rotation about the vertical axis at intervals of 0.1 degrees. Ranging information is obtained by 200 MHz bandwidth chirp modulation of the transmit pulse. Radar resolution is 7m in azimuth at 1 km slant range and 0.75 meters in range. These data are first processed to images in radar coordinates and subsequently transformed to terrain-geocoded map products using an auxiliary DEM. A local terrain model can also be created from interferometric analysis of images acquired from the dual receiving antennas of our instrument. These antennas are separated by 25 cm creating a spatial interferometer. We report radar observations made during the rapid draining of the Gornersee glacial lake at the confluence of the Gorner and Grenz glaciers in Switzerland. These measurements, made in cooperation with ETHZ, cover the period of 21-24 June, 2008. We observe glacier deformation correlated with the drainage event. The nearly continuous radar data exhibit diurnal variations of the influence of water vapor, and decorrelation due to melting on the glacier surface caused by solar heating. A map of LOS velocity of the glaciers visible from the Gornergrat has been produced showing velocities exceeding 300m/year. We also show observations acquired in Triesenberg, Liechtenstein of a large slope landslide moving up to 4 cm/year. Interferograms made from data acquired during January 2007 and

  6. The orbit of Phi Cygni measured with long-baseline optical interferometry - Component masses and absolute magnitudes

    NASA Technical Reports Server (NTRS)

    Armstrong, J. T.; Hummel, C. A.; Quirrenbach, A.; Buscher, D. F.; Mozurkewich, D.; Vivekanand, M.; Simon, R. S.; Denison, C. S.; Johnston, K. J.; Pan, X.-P.

    1992-01-01

    The orbit of the double-lined spectroscopic binary Phi Cygni, the distance to the system, and the masses and absolute magnitudes of its components are presented via measurements with the Mar III Optical Interferometer. On the basis of a reexamination of the spectroscopic data of Rach & Herbig (1961), the values and uncertainties are adopted for the period and the projected semimajor axes from the present fit to the spectroscopic data and the values of the remaining elements from the present fit to the Mark III data. The elements of the true orbit are derived, and the masses and absolute magnitudes of the components, and the distance to the system are calculated.

  7. Group velocity dispersion of CdSSe/ZnS core-shell colloidal quantum dots measured with white light interferometry

    NASA Astrophysics Data System (ADS)

    VanEngen Spivey, Amelia G.

    2016-03-01

    We measure the group velocity dispersion coefficient of CdSSe/ZnS core-shell colloidal quantum dots in liquid suspension in the ∼700-900 nm wavelength range using a white-light Michelson interferometer. Two different sizes of dots are investigated. In both cases, the group velocity dispersion coefficient decreases with increasing wavelength above the absorption edge in the dots. For quantum dots in which the linear absorption spectrum shows clear peaks, the absorption characteristics of the dots can be used to accurately model the wavelength-dependence of the group velocity dispersion coefficient.

  8. Deck and Cable Dynamic Testing of a Single-span Bridge Using Radar Interferometry and Videometry Measurements

    NASA Astrophysics Data System (ADS)

    Piniotis, George; Gikas, Vassilis; Mpimis, Thanassis; Perakis, Harris

    2016-03-01

    This paper presents the dynamic testing of a roadway, single-span, cable-stayed bridge for a sequence of static load and ambient vibration monitoring scenarios. Deck movements were captured along both sideways of the bridge using a Digital Image Correlation (DIC) and a Ground-based Microwave Interfererometer (GBMI) system. Cable vibrations were measured at a single point location on each of the six cables using the GBMI technique. Dynamic testing involves three types of analyses; firstly, vibration analysis and modal parameter estimation (i. e., natural frequencies and modal shapes) of the deck using the combined DIC and GBMI measurements. Secondly, dynamic testing of the cables is performed through vibration analysis and experimental computation of their tension forces. Thirdly, the mechanism of cable-deck dynamic interaction is studied through their Power Spectra Density (PSD) and the Short Time Fourier Transform (STFT) analyses. Thereby, the global (deck and cable) and local (either deck or cable) bridge modes are identified, serving a concrete benchmark of the current state of the bridge for studying the evolution of its structural performance in the future. The level of synergy and complementarity between the GBMI and DIC techniques for bridge monitoring is also examined and assessed.

  9. Full-field vibration measurements of the violin using digital stroboscopic holographic interferometry and electromagnetic stimulation of the strings

    NASA Astrophysics Data System (ADS)

    Keersmaekers, Lissa; Keustermans, William; De Greef, Daniël; Dirckx, Joris J. J.

    2016-06-01

    We developed a setup in which the strings of the violin are driven electromagnetically, and the resulting vibration of the instrument is measured with digital stroboscopic holography. A 250mW single mode green laser beam is chopped using an acousto-optic modulator, generating illumination pulses of 2% of the vibration period. The phase of the illumination pulse is controlled by a programmable function generator so that digital holograms can be recorded on a number of subsequent time positions within the vibration phase. From these recordings, the out of plane motion as a function of time is reconstructed in full field. We show results of full-field vibration amplitude and vibration phase maps, and time resolved full-field deformations of the violin back plane. Time resolved measurements show in detail how the deformation of the violin plane changes as a function of time at different frequencies. We found very different behavior under acoustic stimulation of the instrument and when using electromagnetic stimulation of a string. The aim of the work it to gather data which can be used in power flow calculations to study how the energy of the strings is conducted to the body of the violin and eventually is radiated as sound.

  10. Application of digital holographic interferometry to pressure measurements of symmetric, supercritical and circulation-control airfoils in transonic flow fields

    NASA Technical Reports Server (NTRS)

    Torres, Francisco J.

    1987-01-01

    Six airfoil interferograms were evaluated using a semiautomatic image-processor system which digitizes, segments, and extracts the fringe coordinates along a polygonal line. The resulting fringe order function was converted into density and pressure distributions and a comparison was made with pressure transducer data at the same wind tunnel test conditions. Three airfoil shapes were used in the evaluation to test the capabilities of the image processor with a variety of flows. Symmetric, supercritical, and circulation-control airfoil interferograms provided fringe patterns with shocks, separated flows, and high-pressure regions for evaluation. Regions along the polygon line with very clear fringe patterns yielded results within 1% of transducer measurements, while poorer quality regions, particularly near the leading and trailing edges, yielded results that were not as good.

  11. Nonlinear reflection of a spherically divergent N-wave from a plane surface: Optical interferometry measurements in air

    SciTech Connect

    Karzova, M.; Yuldashev, P.; Khokhlova, V.; Ollivier, S.; Blanc-Benon, Ph.

    2015-10-28

    Mach stem is a well-known structure typically observed in the process of strong (acoustic Mach numbers greater than 0.4) step-shock waves reflection from a rigid boundary. However, this phenomenon has been much less studied for weak shocks in nonlinear acoustic fields where Mach numbers are in the range from 0.001 to 0.01 and pressure waveforms have more complicated waveforms than step shocks. The goal of this work was to demonstrate experimentally how nonlinear reflection occurs in air for very weak spherically divergent acoustic spark-generated pulses resembling an N-wave. Measurements of reflection patterns were performed using a Mach-Zehnder interferometer. A thin laser beam with sub-millimeter cross-section was used to obtain the time resolution of 0.4 µs, which is 6 times higher than the time resolution of the condenser microphones. Pressure waveforms were reconstructed using the inverse Abel transform applied to the phase of the signal measured by the interferometer. The Mach stem formation was observed experimentally as a result of collision of the incident and reflected shock pulses. It was shown that irregular reflection of the pulse occurred in a dynamic way and the length of the Mach stem increased linearly while the pulse propagated along the surface. Since the front shock of the spark-generated pulse was steeper than the rear shock, irregular type of reflection was observed only for the front shock of the pulse while the rear shock reflection occurred in a regular regime.

  12. Measurements of Land Subsidence Rates on the North-western Portion of the Nile Delta Using Radar Interferometry Techniques

    NASA Astrophysics Data System (ADS)

    Fugate, Joseph M.

    The Nile Delta is home to around 75 million people and most of Egypt's farmland and agricultural production. This area is currently threatened by Mediterranean Sea waters due to factors such as sediment starvation, climate change, and sea level fluctuations as well as subsidence. The low elevation and relief of the Nile Delta exposes many coastal communities, including the city of Alexandria, to potential inundation. This situation has become a concern for the area's residents but a better understanding of the processes occurring there can aid in deciding a suitable response. Recent studies have documented Holocene subsidence rates in the northeast part of the Nile Delta that average up to 8mm/year. In this study, PS-InSAR techniques are used to measure modern land subsidence rates on the north-central and north-western Nile Delta. Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) techniques were applied to 23 ESA radar scenes from 2 orbital tracks spanning from 1992 to 2000 in the north-central and north-west portions of the Nile Delta. The area includes the cities of Alexandria, Greater Mahala, and Mansoura as well as the Rosetta promontory and lake Burullus, Idku Lagoon, and Maryut Lagoon. Results indicate that modern average-vertical ground motion velocities for the north-western and north-central Nile Delta range from emergent to subsidence of 8.5 mm/yr. The range of velocities measured are spatially varied in a complex way across the study area. Patterns of subsidence correlate closely to areas of most recent sediment deposition such as along coastlines and rivers, as well as in lagoons and lakes. Average subsidence velocities are also lower across the western sections of the Nile Delta than in the northeastern delta.

  13. The Space Interferometry Mission

    NASA Technical Reports Server (NTRS)

    Unwin, Stephen C.

    1998-01-01

    The Space Interferometry Mission (SIM) is the next major space mission in NASA's Origins program after SIRTF. The SIM architecture uses three Michelson interferometers in low-earth orbit to provide 4 microarcsecond precision absolute astrometric measurements on approx. 40,000 stars. SIM will also provide synthesis imaging in the visible waveband to a resolution of 10 milliarcsecond, and interferometric nulling to a depth of 10(exp -4). A near-IR (1-2 micron) capability is being considered. Many key technologies will be demonstrated by SIM that will be carried over directly or can be readily scaled to future Origins missions such as TPF. The SIM spacecraft will carry a triple Michelson interferometer with baselines in the 10 meter range. Two interferometers act as high precision trackers, providing attitude information at all time, while the third one conducts the science observations. Ultra-accurate laser metrology and active systems monitor the systematic errors and to control the instrument vibrations in order to reach the 4 microarcsecond level on wide-angle measurements. SIM will produce a wealth of new astronomical data. With an absolute positional precision of 4 microarcsecond, SIM will improve on the best currently available measures (the Hipparcos catalog) by 2 or 3 orders of magnitude, providing parallaxes accurate to 10% and transverse velocities to 0.2 km/s anywhere in the Galaxy, to stars as faint as 20th magnitude. With the addition of radial velocities, knowledge of the 6-dimension phase space for objects of interest will allow us to attack a wide array of previously inaccessible problems such as: search for planets down to few earth masses; calibration of stellar luminosities and by means of standard candles, calibration of the cosmic distance scale; detecting perturbations due to spiral arms, disk warps and central bar in our galaxy; probe of the gravitational potential of the Galaxy, several kiloparsecs out of the galactic plane; synthesis imaging

  14. Simultaneous Immersion Mirau Interferometry

    NASA Astrophysics Data System (ADS)

    Lyulko, Oleksandra

    The present work describes a novel imaging technique for label-free no-UV vibration-insensitive imaging of live cells in an epi-illumination geometry. This technique can be implemented in a variety of imaging applications. For example, it can be used for cell targeting as a part of a platform for targeted cell irradiations - single-cell microbeam. The goal of microbeam facilities is to provide biological researchers with tools to study the effects of ionizing radiation on live cells. A common way of cell labeling - fluorescent staining - may alter cellular metabolism and UV illumination presents potential damage for the genetic material. The new imaging technique will allow the researchers to separate radiation-induced effects from the effects caused by confounding factors like fluorescent staining or UV light. Geometry of irradiation endstations at some microbeam facilities precludes the use of transmitted light, e.g. in the Columbia University's Radiological Research Accelerator Facility microbeam endstation, where the ion beam exit window is located just below the sample. Imaging techniques used at such endstations must use epi-illumination. Mirau Interferometry is an epi-illumination, non-stain imaging modality suitable for implementation at a microbeam endstation. To facilitate interferometry and to maintain cell viability, it is desirable that cells stay in cell growth medium during the course of an experiment. To accommodate the use of medium, Immersion Mirau Interferometry has been developed. A custom attachment for a microscope objective has been designed and built for interferometric imaging with the possibility of immersion of the apparatus into cell medium. The implemented data collection algorithm is based on the principles of Phase-Shifting Interferometry. The largest limitation of Phase-Shifting Interferometry is its sensitivity to the vertical position of the sample. In environments where vibration isolation is difficult, this makes image

  15. Null Stellar Intensity Interferometry

    NASA Astrophysics Data System (ADS)

    Tan, P. K.; Chia, C. M.; Han, W. D.; Chan, A. H.; Kurtsiefer, C.

    2014-04-01

    Since the discovery of the first exoplanet in 1989, though over 850 candidates have been verified (Schneider 2012), few are similar to our Earth in terms of mass and size. Hence here we would like to propose the revival and improvement of optical intensity interferometry to achieve sub-milliarcsecond resolution, which promises also to be less sensitive to weather conditions, light pollution and optomechanical alignments, yet only requiring baselines <100m.

  16. DISTANCE AND PROPER MOTION MEASUREMENT OF THE RED SUPERGIANT, PZ CAS, IN VERY LONG BASELINE INTERFEROMETRY H{sub 2}O MASER ASTROMETRY

    SciTech Connect

    Kusuno, K.; Asaki, Y.; Imai, H.; Oyama, T. E-mail: asaki@vsop.isas.jaxa.jp E-mail: t.oyama@nao.ac.jp

    2013-09-10

    We present the very long baseline interferometry H{sub 2}O maser monitoring observations of the red supergiant, PZ Cas, at 12 epochs from 2006 April to 2008 May. We fitted maser motions to a simple model composed of a common annual parallax and linear motions of the individual masers. The maser motions with the parallax subtracted were well modeled by a combination of a common stellar proper motion and a radial expansion motion of the circumstellar envelope. We obtained an annual parallax of 0.356 {+-} 0.026 mas and a stellar proper motion of {mu}{sub {alpha}}{sup *} cos {delta} = -3.7 {+-} 0.2 and {mu}{sup *}{sub {delta}}=-2.0{+-}0.3 mas yr{sup -1} eastward and northward, respectively. The annual parallax corresponds to a trigonometric parallax of 2.81{sup +0.22}{sub -0.19} kpc. By rescaling the luminosity of PZ Cas in any previous studies using our trigonometric parallax, we estimated the location of PZ Cas on a Hertzsprung-Russell diagram and found that it approaches a theoretically evolutionary track around an initial mass of {approx}25 M{sub Sun }. The sky position and the distance to PZ Cas are consistent with the OB association, Cas OB5, which is located in a molecular gas super shell. The proper motion of PZ Cas is close to that of the OB stars and other red supergiants in Cas OB5 measured by the Hipparcos satellite. We derived the peculiar motion of PZ Cas of U{sub s} = 22.8 {+-} 1.5, V{sub s} = 7.1 {+-} 4.4, and W{sub s} = -5.7 {+-} 4.4 km s{sup -1}. This peculiar motion has rather a large U{sub s} component, unlike those of near high-mass star-forming regions with negatively large V{sub s} motions. The uniform proper motions of the Cas OB5 member stars suggest random motions of giant molecular clouds moving into local potential minima in a time-dependent spiral arm, rather than a velocity field caused by the spiral arm density wave.

  17. Antimatter interferometry for gravity measurements.

    PubMed

    Hamilton, Paul; Zhmoginov, Andrey; Robicheaux, Francis; Fajans, Joel; Wurtele, Jonathan S; Müller, Holger

    2014-03-28

    We describe a light-pulse atom interferometer that is suitable for any species of atom and even for electrons and protons as well as their antiparticles, in particular, for testing the Einstein equivalence principle with antihydrogen. The design obviates the need for resonant lasers through far-off resonant Bragg beam splitters and makes efficient use of scarce atoms by magnetic confinement and atom recycling. We expect to reach an initial accuracy of better than 1% for the acceleration of the free fall of antihydrogen, which can be improved to the part-per million level. PMID:24724644

  18. Applications of whole field interferometry in mechanics and acoustics

    NASA Astrophysics Data System (ADS)

    Molin, Nils-Erik

    1999-07-01

    A description is given of fringe formation in holographic interferometry, in electronic speckle pattern interferometry, in electro-optic or TV holography and for a newly developed system for pulsed TV-holography. A numerical example, which simulates the equations describing the different techniques, is included. A strain measuring system using defocused digital speckle photography is described. Experiments showing mode shapes of musical instruments, transient bending wave propagation in beams and plates as well as sound pressure fields in air are included.

  19. Spatial interferometry in optical astronomy

    NASA Technical Reports Server (NTRS)

    Gezari, Daniel Y.; Roddier, Francois; Roddier, Claude

    1990-01-01

    A bibliographic guide is presented to publications of spatial interferometry techniques applied to optical astronomy. Listings appear in alphabetical order, by first author, as well as in specific subject categories listed in chronological order, including imaging theory and speckle interferometry, experimental techniques, and observational results of astronomical studies of stars, the Sun, and the solar system.

  20. Determination of thin hydrodynamic lubricating film thickness using dichromatic interferometry.

    PubMed

    Guo, L; Wong, P L; Guo, F; Liu, H C

    2014-09-10

    This paper introduces the application of dichromatic interferometry for the study of hydrodynamic lubrication. In conventional methods, two beams with different colors are projected consecutively on a static object. By contrast, the current method deals with hydrodynamic lubricated contacts under running conditions and two lasers with different colors are projected simultaneously to form interference images. Dichromatic interferometry incorporates the advantages of monochromatic and chromatic interferometry, which are widely used in lubrication research. This new approach was evaluated statically and dynamically by measuring the inclination of static wedge films and the thickness of the hydrodynamic lubricating film under running conditions, respectively. Results show that dichromatic interferometry can facilitate real-time determination of lubricating film thickness and is well suited for the study of transient or dynamic lubricating problems. PMID:25321689

  1. Pressure and temperature dependence of the elasticity of pyrope-majorite [Py 60Mj 40 and Py 50Mj 50] garnets solid solution measured by ultrasonic interferometry technique

    NASA Astrophysics Data System (ADS)

    Gwanmesia, Gabriel D.; Wang, Liping; Triplett, Richard; Liebermann, Robert C.

    2009-05-01

    Compressional (P) and shear (S) wave velocities have been measured for two synthetic polycrystalline specimens of pyrope-majorite garnets [Py 60Mj 40 and Py 50Mj 50] by ultrasonic interferometry to 8 GPa and 1000 K, in a DIA-type cubic anvil high pressure apparatus (SAM-85) interfaced with synchrotron X-radiation and X-ray imaging. Elastic bulk ( KS) and shear ( G) moduli data obtained at the end of the cooling cycles were fitted to functions of Eulerian strain to third order yielding pressure derivatives of the elastic moduli (∂ KS/∂ P) T = 4.3 (3); (∂ G/∂ P) T = 1.5 (1) for Py 60Mj 40 garnet and (∂ KS/∂ P) T = 4.4 (1); (∂ G/∂ P) T = 1.3 (1) for Py 50Mj 40 garnet. Both (∂ KS/∂ P) T and (∂ G/∂ P) T are identical for the two garnet compositions and are also consistent with Brillouin scattering data for polycrystalline Py 50Mj 50. Moreover, the new pressure derivatives of the elastic moduli are equal within experimental uncertainties to those of end-member pyrope garnet from ultrasonic studies [Gwanmesia, G.D., Zhang. J, Darling, K., Kung, J., Li, B., Wang, L., Neuville, D., Liebermann, R.C., 2006. Elasticity of polycrystalline pyrope (Mg 3Al 2Si 3O 12) to 9 GPa and 1000 °C. Phys. Earth Planet. Inter. 155, 179-190] and from Brillouin spectroscopic studies [Sinogeikin, S.V., Bass, J.D., 2002a. Elasticity of majorite and majorite-pyrope solid solution to high pressure: implications for the transition zone. Geophys. Res. 9(2), 1017], thereby demonstrating that the pressure derivatives of the elastic moduli are independent of the physical acoustics technique employed and unaffected by substitution of Si for Mg and Al within the Py-Mj solid solution in the range (Py 100-Py 50) of the present measurements. Temperature dependence of the elastic obtained from linear regression of entire P- T- K and P- T- G data are (∂ KS/∂ T) P = -14.6 (4) MPa/K; (∂ G/∂ T) P = -9.4 (4) MPa/K for Py 60Mj 40 garnet, and (∂ KS/∂ T) P = -14.6 (4) MPa/K; (

  2. Near-Earth Object Astrometric Interferometry

    NASA Technical Reports Server (NTRS)

    Werner, Martin R.

    2005-01-01

    Using astrometric interferometry on near-Earth objects (NEOs) poses many interesting and difficult challenges. Poor reflectance properties and potentially no significant active emissions lead to NEOs having intrinsically low visual magnitudes. Using worst case estimates for signal reflection properties leads to NEOs having visual magnitudes of 27 and higher. Today the most sensitive interferometers in operation have limiting magnitudes of 20 or less. The main reason for this limit is due to the atmosphere, where turbulence affects the light coming from the target, limiting the sensitivity of the interferometer. In this analysis, the interferometer designs assume no atmosphere, meaning they would be placed at a location somewhere in space. Interferometer configurations and operational uncertainties are looked at in order to parameterize the requirements necessary to achieve measurements of low visual magnitude NEOs. This analysis provides a preliminary estimate of what will be required in order to take high resolution measurements of these objects using interferometry techniques.

  3. Permafrost Active Layer Seismic Interferometry Experiment (PALSIE).

    SciTech Connect

    Abbott, Robert; Knox, Hunter Anne; James, Stephanie; Lee, Rebekah; Cole, Chris

    2016-01-01

    We present findings from a novel field experiment conducted at Poker Flat Research Range in Fairbanks, Alaska that was designed to monitor changes in active layer thickness in real time. Results are derived primarily from seismic data streaming from seven Nanometric Trillium Posthole seismometers directly buried in the upper section of the permafrost. The data were evaluated using two analysis methods: Horizontal to Vertical Spectral Ratio (HVSR) and ambient noise seismic interferometry. Results from the HVSR conclusively illustrated the method's effectiveness at determining the active layer's thickness with a single station. Investigations with the multi-station method (ambient noise seismic interferometry) are continuing at the University of Florida and have not yet conclusively determined active layer thickness changes. Further work continues with the Bureau of Land Management (BLM) to determine if the ground based measurements can constrain satellite imagery, which provide measurements on a much larger spatial scale.

  4. Stitching interferometry: recent results and absolute calibration

    NASA Astrophysics Data System (ADS)

    Bray, Michael

    2004-02-01

    Stitching Interferometry is a method of analysing large optical components using a standard "small" interferometer. This result is obtained by taking multiple overlapping images of the large component, and numerically "stitching" these sub-apertures together. We have already reported the industrial use our Stitching Interferometry systems (Previous SPIE symposia), but experimental results had been lacking because this technique is still new, and users needed to get accustomed to it before producing reliable measurements. We now have more results. We will report user comments and show new, unpublished results. We will discuss sources of error, and show how some of these can be reduced to arbitrarily small values. These will be discussed in some detail. We conclude with a few graphical examples of absolute measurements performed by us.

  5. Two color holographic interferometry for microgravity application

    NASA Technical Reports Server (NTRS)

    Trolinger, James D.; Weber, David C.

    1995-01-01

    Holographic interferometry is a primary candidate for determining temperature and concentration in crystal growth experiments designed for space. The method measures refractive index changes within the fluid of an experimental test cell resulting from temperature and/or concentration changes. When the refractive index changes are caused by simultaneous temperature and concentration changes, the contributions of the two effects cannot be separated by single wavelength interferometry. By using two wavelengths, however, two independent interferograms can provide the additional independent equation required to determine the two unknowns. There is no other technique available that provides this type of information. The primary objectives of this effort were to experimentally verify the mathematical theory of two color holographic interferometry (TCHI) and to determine the practical value of this technique for space application. In the foregoing study, the theory of TCHI has been tested experimentally over a range of interest for materials processing in space where measurements of temperature and concentration in a solution are required. New techniques were developed and applied to stretch the limits beyond what could be done with existing procedures. The study resulted in the production of one of the most advanced, enhanced sensitivity holographic interferometers in existence. The interferometric measurements made at MSFC represent what is believed to be the most accurate holographic interferometric measurements made in a fluid to date. The tests have provided an understanding of the limitations of the technique in practical use.

  6. Kaon decay interferometry as meson dynamics probes

    NASA Astrophysics Data System (ADS)

    D'ambrosio, G.; Paver, N.

    1994-05-01

    We discuss the time-dependent interferences between KL and KS in the decays in 3π and ππγ, to be studied at interferometry machines such as the φ factory and CERN LEAR. We emphasize the possibilities and the advantages of using interferences, in comparision with width measurements, to obtain information both on CP-conserving and CP-violating amplitudes. Comparision with present data and suggestions for future experiments are made.

  7. The Lindley paradox in optical interferometry

    NASA Astrophysics Data System (ADS)

    Mauri, Camillo; Paris, Matteo G. A.

    2016-02-01

    The so-called Lindley paradox is a counterintuitive statistical effect where the Bayesian and frequentist approaches to hypothesis testing give radically different answers, depending on the choice of the prior distribution. In this paper we address the occurrence of the Lindley paradox in optical interferometry and discuss its implications for high-precision measurements. In particular, we focus on phase estimation by Mach-Zehnder interferometers and show how to mitigate the conflict between the two approaches by using suitable priors.

  8. Moire interferometry for thermal expansion of composites

    NASA Technical Reports Server (NTRS)

    Bowles, D. E.; Tenney, D. R.; Post, D.; Herakovich, C. T.

    1981-01-01

    Moire interferometry by reflection has been demonstrated using a real reference grating of 1200 lines/mm. The method is shown to be well adapted to thermal environments. Thermal expansion coefficients of graphite-epoxy composites have been measured with high precision over a wide range from nearly zero to 3300 microstrains in the temperature range 297-422 K. Random errors characterized by one standard deviation can be as small as one microstrain.

  9. Stitching interferometry of aspherical surfaces

    NASA Astrophysics Data System (ADS)

    Haensel, Thomas; Nickel, Andreas; Schindler, Axel

    2001-12-01

    Sub-aperture stitching interferometry (SASI) is an appropriate method to measure either large optical plane surface topologies or aspheres with strong deviation from the flatness with standard interferometers. Using SASI the surface shape is measured with a higher lateral resolution by multiple adjacent sub-aperture measurements with a sufficient overlap of the neighboring areas. In a second step, the total surface shape is composed with the help of a computer code by stitching the sub-aperture areas together. The overlap areas allow fitting. By means of a regression analysis, tilt and vertical displacement of adjacent areas are calculated and minimized. A confidence band calculated using a MATLAB based code describes the accuracy of the composition. The variance of this estimation is inverse proportional to the peak to valley value (PV) of the measured area and decreases with a 10-3 scaling of the width of the overlapping area. A statistical experimental design method is used to minimize the number of sub-apertures to be measured. The accuracy of the stitched total surface measurement can be increased with the help of model calculations by optimizing (i) the position of the sub-aperture, which was regarded as a standard, and (ii) the sequence of the stitched adjacent areas.

  10. Two color holographic interferometry for microgravity application

    NASA Technical Reports Server (NTRS)

    Trolinger, James D.

    1993-01-01

    Holographic interferometry is a primary candidate for the measurement of temperature and concentration in various crystal growth experiments destined for space. The method measures refractive index changes in the experiment test cell. A refractive index change can be caused by concentration changes, temperature changes, or a combination of temperature and concentration changes. If the refractive index changes are caused by temperature and concentration changes occurring simultaneously in the experiment test cell, the contributions by the two effects cannot be separated by conventional measurement methods. By using two wavelengths, two independent interferograms can be produced from the reconstruction of the hologram. The two interferograms will be different due to dispersion properties of fluid materials. These differences provide the additional information that allows the separation of simultaneously occurring temperature and concentration gradients. There is no other technique available that can provide this type of information. The primary objectives of this effort are to experimentally verify the mathematical theory of two color holographic interferometry and to determine the practical value of this technique for space application. To achieve these objectives, the accuracy and sensitivity of the technique must be determined for geometry's and materials that are relevant to the Materials Processing in the Space program of NASA. This will be achieved through the use of a specially designed two-color holographic interferometry breadboard optical system. In addition to experiments to achieve the primary goals, the breadboard will also provide inputs to the design of an optimum space flight system.

  11. Temperature measurement of axi- symmetric butane diffusion flame under the influence of upward decreasing gradient magnetic field using digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Kumar, Varun; Kumar, Manoj; Shakher, Chandra

    2015-08-01

    In this paper, digital holographic interferometry (DHI) is implemented to investigate the effect of upward decreasing gradient magnetic field on the temperature and temperature profile of diffusion flame created by butane torch burner. In the experiment double exposure digital holographic interferometry is used to calculate the temperature distribution inside the flame. First a digital hologram is recorded in the absence of flame and second hologram is recorded in the presence of flame. Phases in two different states of air (i.e. in absence of flame and presence of flame) are reconstructed individually by numerical method. The phase difference map is obtained by subtracting the reconstructed phase of air in presence and absence of flame. Refractive index inside the flame is obtained from the axi-symmetric phase difference data using the Abel inversion integral. Temperature distribution inside the flame is calculated from the refractive index data using Lorentz - Lorentz equation. Experiment is conducted on a diffusion flame created by butane torch burner in the absence of magnetic field and in presence of upward decreasing gradient magnetic field. Experimental investigations reveal that the maximum temperature inside the flame increases under the influence of upward decreasing magnetic field.

  12. Complex master slave interferometry.

    PubMed

    Rivet, Sylvain; Maria, Michael; Bradu, Adrian; Feuchter, Thomas; Leick, Lasse; Podoleanu, Adrian

    2016-02-01

    A general theoretical model is developed to improve the novel Spectral Domain Interferometry method denoted as Master/Slave (MS) Interferometry. In this model, two functions, g and h are introduced to describe the modulation chirp of the channeled spectrum signal due to nonlinearities in the decoding process from wavenumber to time and due to dispersion in the interferometer. The utilization of these two functions brings two major improvements to previous implementations of the MS method. A first improvement consists in reducing the number of channeled spectra necessary to be collected at Master stage. In previous MSI implementation, the number of channeled spectra at the Master stage equated the number of depths where information was selected from at the Slave stage. The paper demonstrates that two experimental channeled spectra only acquired at Master stage suffice to produce A-scans from any number of resolved depths at the Slave stage. A second improvement is the utilization of complex signal processing. Previous MSI implementations discarded the phase. Complex processing of the electrical signal determined by the channeled spectrum allows phase processing that opens several novel avenues. A first consequence of such signal processing is reduction in the random component of the phase without affecting the axial resolution. In previous MSI implementations, phase instabilities were reduced by an average over the wavenumber that led to reduction in the axial resolution. PMID:26906857

  13. Atom interferometry in an optical cavity.

    PubMed

    Hamilton, Paul; Jaffe, Matt; Brown, Justin M; Maisenbacher, Lothar; Estey, Brian; Müller, Holger

    2015-03-13

    We propose and demonstrate a new scheme for atom interferometry, using light pulses inside an optical cavity as matter wave beam splitters. The cavity provides power enhancement, spatial filtering, and a precise beam geometry, enabling new techniques such as low power beam splitters (<100  μW), large momentum transfer beam splitters with modest power, or new self-aligned interferometer geometries utilizing the transverse modes of the optical cavity. As a first demonstration, we obtain Ramsey-Raman fringes with >75% contrast and measure the acceleration due to gravity, g, to 60  μg/sqrt[Hz] resolution in a Mach-Zehnder geometry. We use >10(7) cesium atoms in the compact mode volume (600  μm 1/e(2) waist) of the cavity and show trapping of atoms in higher transverse modes. This work paves the way toward compact, high sensitivity, multiaxis interferometry. PMID:25815912

  14. Atom Interferometry in an Optical Cavity

    NASA Astrophysics Data System (ADS)

    Hamilton, Paul; Jaffe, Matt; Brown, Justin M.; Maisenbacher, Lothar; Estey, Brian; Müller, Holger

    2015-03-01

    We propose and demonstrate a new scheme for atom interferometry, using light pulses inside an optical cavity as matter wave beam splitters. The cavity provides power enhancement, spatial filtering, and a precise beam geometry, enabling new techniques such as low power beam splitters (<100 μ W ), large momentum transfer beam splitters with modest power, or new self-aligned interferometer geometries utilizing the transverse modes of the optical cavity. As a first demonstration, we obtain Ramsey-Raman fringes with >75 % contrast and measure the acceleration due to gravity, g , to 60 μ g /√{Hz } resolution in a Mach-Zehnder geometry. We use >107 cesium atoms in the compact mode volume (600 μ m 1 /e2 waist) of the cavity and show trapping of atoms in higher transverse modes. This work paves the way toward compact, high sensitivity, multiaxis interferometry.

  15. Hidden observables in neutron quantum interferometry

    NASA Astrophysics Data System (ADS)

    Rauch, Helmut; Baron, Matthias; Filipp, Stefan; Hasegawa, Yuji; Lemmel, Hartmut; Loidl, Rudolf

    2006-11-01

    Neutron interferometry using monolithic perfect single crystals has become an important tool for fundamental, nuclear, and solid-state physics research. New features of quantum mechanics become measurable by means of neutron interferometry. Such features are quantum phases, which provide a more direct access to properties of wave functions and permit wave function reconstruction, and wave function engineering. Most recently, new experiments concerning off-diagonal and non-cyclic geometrical phases, confinement induced phases, and contextuality related experiments have been performed. These experiments show an intrinsic entanglement of different degrees of freedom of a single particle. Proper post-selection experiments yield to more quantum complete experiments and may help to make quantum mechanics less mystic. Unavoidable quantum losses may play an important role to explain the transition from the quantum to the classical world. All these investigations concern the heart of quantum mechanics and demonstrate the non-local feature of this theory.

  16. Use of interferometry in preschool children.

    PubMed

    Richman, J E; Kozol, N; Crawford, R D

    1989-05-01

    Any procedure that can help to predict the outcome of treatment for a vision disorder is a desired clinical goal. Interferometry has shown such an ability for predicting the post-treatment visual acuities in amblyopia and other vision disorders. In this study, we investigated the effectiveness of using interferometry with preschool children, aged 3-5 years. We determined that they can be reliably tested in 5-10 minutes using a non-verbal, forced choice technique. Due to developmental differences, the 3-year-olds needed slightly more time to test and were more variable in their responses than the 4-years-olds. Overall, the prognostic value of interferometer visual acuity measures should be considered for use in preschool children with visual acuity disorders, e.g., amblyopia. PMID:2732416

  17. Dual-polarization interferometry: an analytical technique to measure changes in protein structure in real time, to determine the stoichiometry of binding events, and to differentiate between specific and nonspecific interactions.

    PubMed

    Swann, Marcus J; Peel, Louise L; Carrington, Simon; Freeman, Neville J

    2004-06-15

    The study of solution-phase interactions between small molecules and immobilized proteins is of intense interest, especially to the pharmaceutical industry. An optical sensing technique, dual polarization interferometry, has been employed for the detailed study of a model protein system, namely, d-biotin interactions with streptavidin immobilized on a solid surface. Changes in thickness and density of an immobilized streptavidin layer as a result of the binding of d-biotin have been directly measured in solution and in real time. The results obtained from this approach are in excellent agreement with X-ray crystallographic data for the structural changes expected in the streptavidin-D-biotin system. The mass changes measured on binding d-biotin also agree closely with anticipated binding capacity values. Determination of the density changes occurring in the protein adlayer provides a means for differentiation between specific and nonspecific interactions. PMID:15158477

  18. Optical interferometry in fluid dynamics research

    NASA Technical Reports Server (NTRS)

    Bachalo, W. D.; Houser, M. J.

    1987-01-01

    Optical interferometry techniques were applied to the investigation of transonic airfoil flow fields in large wind tunnels. Holographic interferometry techniques were used to study 2 dimensional symmetric NACA 64A010 and Douglas Aircraft Co. DSMA671 supercritical airfoil performance in the NASA Ames 2 x 2 ft transonic wind tunnel. Quantitative data obtained from the interferograms were compared to the surface pressure data. The agreement obtained verified the accuracy of the flow visualization and demonstrated the potential for acquiring quantitative scalar results. Measurements of the inviscid flow speed and the boundary layer and wake velocity profiles were extracted from the interferograms and compared to laser Doppler velocimeter measurements. These results were also in good agreement. A method for acquiring real time interferometric data in large scale facilities was developed. This method, based on the point diffraction interferometer, was successfully tested in the 2 x 2 ft transonic wind tunnel. The holographic and real time interferometry methods were applied to the investigations of circulation control airfoils utilizing the Coanda effect. These results reveals the details of the jet interacting with the trailing edge boundary layer and the other parameters affecting the lift augmentation.

  19. Optical interferometry in fluid dynamics research

    NASA Technical Reports Server (NTRS)

    Bachalo, W. D.; Houser, M. J.

    1985-01-01

    Optical interferometry techniques have been applied to the investigation of transonic airfoil flow fields in large-scale wind tunnels. Holographic interferometry techniques were used in the study of two-dimensional symmetric NACA 64A010 and Douglas Aircraft Company DSMA671 supercritical airfoil performance in the NASA Ames 2 ft x 2 ft transonic wind tunnel. Quantitative data obtained from the interferograms were compared to the surface pressure data. The excellent agreement obtained verified the accuracy of the flow visualization and demonstrated the potential for acquiring quantitative scalar results. Measurements of the inviscid flow speed and the boundary layer and wake velocity profiles were extracted from the interferograms and compared to laser Doppler velocimeter measurements. These results were also in good agreement. A method for acquiring real-time interferometric data in large-scale facilities was developed. This method, based on the point diffraction interferometer, was successfully tested in the Ames 2 ft x 2 ft transonic wind tunnel. The holographic and real-time interferometry methods were applied to the investigations of circulation control airfoils utilizing the Coanda effect. These results revealed the details of the jet interaction with the trailing edge boundary layer and the other parameters affecting the lift augmentation.

  20. Atom Interferometry on a Sounding Rocket

    NASA Astrophysics Data System (ADS)

    Becker, Dennis; Seidel, Stephan; Lachmann, Maike; Rasel, Ernst; Quantus Collaboration

    2015-05-01

    The universality of free fall is one of the fundamental postulates of our description of nature. The comparison of the free fall of two ultra-cold clouds of different atomic species via atom interferometry comprises a method to precisely test this assumption. By performing the experiments in a microgravity environment the sensitivity of such an atom interferometric measurement can be increased. In order to fully utilize the potential of these experiments the usage of a Bose-Einstein condensate as the initial state of the atom interferometer is necessary. As a step towards the transfer of such a system in space an atom optical experiment is currently being prepared as the scientific payload for a sounding rocket mission. This mission is aiming at the first demonstration of a Bose-Einstein condensate in space and using this quantum degenerate matter as a source for atom interferometry. The launch of the rocket is planned for 2015 from ESRANGE. This first mission will be followed by two more that extend the scientific goals to the creation of degenerate mixtures in space and simultaneous atom interferometry with two atomic species. Their success would mark a major advancement towards a precise measurement of the universality of free fall with a space-born atom interferometer. This research is funded by the German Space Agency DLR under grant number DLR 50 1131-37.

  1. Intellectual property in holographic interferometry

    NASA Astrophysics Data System (ADS)

    Reingand, Nadya; Hunt, David

    2006-08-01

    This paper presents an overview of patents and patent applications on holographic interferometry, and highlights the possibilities offered by patent searching and analysis. Thousands of patent documents relevant to holographic interferometry were uncovered by the study. The search was performed in the following databases: U.S. Patent Office, European Patent Office, Japanese Patent Office and Korean Patent Office for the time frame from 1971 through May 2006. The patent analysis unveils trends in patent temporal distribution, patent families formation, significant technological coverage within the market of system that employ holographic interferometry and other interesting insights.

  2. Shaken lattice interferometry

    NASA Astrophysics Data System (ADS)

    Weidner, Carrie; Yu, Hoon; Anderson, Dana

    2016-05-01

    In this work, we report on progress towards performing interferometry using atoms trapped in an optical lattice. That is, we start with atoms in the ground state of an optical lattice potential V(x) =V0cos [ 2 kx + ϕ(t) ] , and by a prescribed phase function ϕ(t) , transform from one atomic wavefunction to another. In this way, we implement the standard interferometric sequence of beam splitting, propagation, reflection, reverse propagation, and recombination. Through the use of optimal control techniques, we have computationally demonstrated a scalable accelerometer that provides information on the sign of the applied acceleration. Extension of this idea to a two-dimensional shaken-lattice-based gyroscope is discussed. In addition, we report on the experimental implementation of the shaken lattice system.

  3. Spectroscopic Low Coherence Interferometry

    NASA Astrophysics Data System (ADS)

    Bosschaart, Nienke; van Leeuwen, T. G.; Aalders, Maurice C.; Hermann, Boris; Drexler, Wolfgang; Faber, Dirk J.

    Low-coherence interferometry (LCI) allows high-resolution volumetric imaging of tissue morphology and provides localized optical properties that can be related to the physiological status of tissue. This chapter discusses the combination of spatial and spectroscopic information by means of spectroscopic OCT (sOCT) and low-coherence spectroscopy (LCS). We describe the theory behind these modalities for the assessment of spatially resolved optical absorption and (back)scattering coefficient spectra. These spectra can be used for the highly localized quantification of chromophore concentrations and assessment of tissue organization on (sub)cellular scales. This leads to a wealth of potential clinical applications, ranging from neonatology for the determination of billibrubin concentrations, to oncology for the optical assessment of the aggressiveness of a cancerous lesion.

  4. Portable intensity interferometry

    NASA Astrophysics Data System (ADS)

    Horch, Elliott P.; Camarata, Matthew A.

    2012-07-01

    A limitation of the current generation of long baseline optical interferometers is the need to make the light interfere prior to detection. This is unlike the radio regime where signals can be recorded fast enough to use electronics to accomplish the same result. This paper describes a modern optical intensity interferometer based on electronics with picosecond timing resolution. The instrument will allow for portable optical interferometry with much larger baselines than currently possible by using existing large telescopes. With modern electronics, the limiting magnitude of the technique at a 4-m aperture size becomes competitive with some amplitude-based interferometers. The instrumentation will permit a wireless mode of operation with GPS clocking technology, extending the work to extremely large baselines. We discuss the basic observing strategy, a planned observational program at the Lowell Observatory 1.8-m and 1.0-m telescopes, and the science that can realistically be done with this instrumentation.

  5. Interferometry for rotating sources

    NASA Astrophysics Data System (ADS)

    Velle, S.; Mehrabi Pari, S.; Csernai, L. P.

    2016-06-01

    The two particle interferometry method to determine the size of the emitting source after a heavy ion collision is extended. Following the extension of the method to spherical expansion dynamics, here we extend the method to rotating systems. It is shown that rotation of a cylindrically symmetric system leads to modifications, which can be perceived as spatial asymmetry by the "azimuthal HBT" method. We study an exact rotating and expanding solution of the fluid dynamical model of heavy ion reactions. We consider a source that is azimuthally symmetric in space around the axis of rotation, and discuss the features of the resulting two particle correlation function. This shows the azimuthal asymmetry arising from the rotation. We show that this asymmetry leads to results similar to those given by spatially asymmetric sources.

  6. Optical Long Baseline Interferometry News

    NASA Astrophysics Data System (ADS)

    Lawson, P. R.; Malbet, F.

    2005-12-01

    The Optical Long Baseline Interferometry News is a website and forum for scientists, engineers, and students who share an interest in long baseline stellar interferometry. It was established in 1995 and is the focus of activity of the IAU Working Group on Optical/Infrared Interferometry. Here you will find links to projects devoted to stellar interferometry, news items, recent papers and preprints, and resources for further research. The email news forum was established in 2001 to complement the website and to facilitate exchanges and collaborations. The forum includes an email exploder and an archived list of discussions. You are invited to explore the forum and website at http://olbin.jpl.nasa.gov. Work by PRL was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  7. Development of Speckle Interferometry Algorithm and System

    SciTech Connect

    Shamsir, A. A. M.; Jafri, M. Z. M.; Lim, H. S.

    2011-05-25

    Electronic speckle pattern interferometry (ESPI) method is a wholefield, non destructive measurement method widely used in the industries such as detection of defects on metal bodies, detection of defects in intergrated circuits in digital electronics components and in the preservation of priceless artwork. In this research field, this method is widely used to develop algorithms and to develop a new laboratory setup for implementing the speckle pattern interferometry. In speckle interferometry, an optically rough test surface is illuminated with an expanded laser beam creating a laser speckle pattern in the space surrounding the illuminated region. The speckle pattern is optically mixed with a second coherent light field that is either another speckle pattern or a smooth light field. This produces an interferometric speckle pattern that will be detected by sensor to count the change of the speckle pattern due to force given. In this project, an experimental setup of ESPI is proposed to analyze a stainless steel plate using 632.8 nm (red) wavelength of lights.

  8. Development of Speckle Interferometry Algorithm and System

    NASA Astrophysics Data System (ADS)

    Shamsir, A. A. M.; Jafri, M. Z. M.; Lim, H. S.

    2011-05-01

    Electronic speckle pattern interferometry (ESPI) method is a wholefield, non destructive measurement method widely used in the industries such as detection of defects on metal bodies, detection of defects in intergrated circuits in digital electronics components and in the preservation of priceless artwork. In this research field, this method is widely used to develop algorithms and to develop a new laboratory setup for implementing the speckle pattern interferometry. In speckle interferometry, an optically rough test surface is illuminated with an expanded laser beam creating a laser speckle pattern in the space surrounding the illuminated region. The speckle pattern is optically mixed with a second coherent light field that is either another speckle pattern or a smooth light field. This produces an interferometric speckle pattern that will be detected by sensor to count the change of the speckle pattern due to force given. In this project, an experimental setup of ESPI is proposed to analyze a stainless steel plate using 632.8 nm (red) wavelength of lights.

  9. Azimuthal-angle dependence of charged-pion-interferometry measurements with respect to second- and third-order event planes in Au+Au collisions at √[S(NN)]=200  GeV.

    PubMed

    Adare, A; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Bataineh, H; Alexander, J; Aoki, K; Aramaki, Y; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Bennett, R; Berdnikov, A; Berdnikov, Y; Bickley, A A; Bok, J S; Boyle, K; Brooks, M L; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Camacho, C M; Campbell, S; Chen, C-H; Chi, C Y; Chiu, M; Choi, I J; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Connors, M; Constantin, P; Csanád, M; Csörgő, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Dutta, D; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Fields, D E; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Garishvili, I; Glenn, A; Gong, H; Gonin, M; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-Å; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Hartouni, E P; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Ide, J; Ikeda, Y; Imai, K; Inaba, M; Isenhower, D; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Ivanischev, D; Jacak, B V; Jia, J; Jin, J; Johnson, B M; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kang, J H; Kapustinsky, J; Karatsu, K; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kim, B I; Kim, D H; Kim, D J; Kim, E; Kim, E-J; Kim, S H; Kim, Y-J; Kinney, E; Kiriluk, K; Kiss, A; Kistenev, E; Kochenda, L; Komkov, B; Konno, M; Koster, J; Kotchetkov, D; Kozlov, A; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K; Lee, K B; Lee, K S; Leitch, M J; Leite, M A L; Leitner, E; Lenzi, B; Li, X; Liebing, P; Linden Levy, L A; Liška, T; Litvinenko, A; Liu, H; Liu, M X; Love, B; Luechtenborg, R; Lynch, D; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Mannel, E; Mao, Y; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; Means, N; Meredith, B; Miake, Y; Mignerey, A C; Mikeš, P; Miki, K; Milov, A; Mishra, M; Mitchell, J T; Mohanty, A K; Morino, Y; Morreale, A; Morrison, D P; Moukhanova, T V; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, T; Nakano, K; Newby, J; Nguyen, M; Niida, T; Nouicer, R; Nyanin, A S; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, I H; Park, J; Park, S K; Park, W J; Pate, S F; Pei, H; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, K F; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Ružička, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Samsonov, V; Sano, S; Sato, T; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Semenov, A Yu; Seto, R; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slunečka, M; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Sparks, N A; Stankus, P W; Stenlund, E; Stoll, S P; Sugitate, T; Sukhanov, A; Sziklai, J; Takagui, E M; Taketani, A; Tanabe, R; Tanaka, Y; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tarján, P; Themann, H; Thomas, T L; Todoroki, T; Togawa, M; Toia, A; Tomášek, L; Torii, H; Towell, R S; Tserruya, I; Tsuchimoto, Y; Vale, C; Valle, H; van Hecke, H W; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Vinogradov, A A; Virius, M; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Wei, F; Wei, R; Wessels, J; White, S N; Winter, D; Wood, J P; Woody, C L; Wright, R M; Wysocki, M; Xie, W; Yamaguchi, Y L; Yamaura, K; Yang, R; Yanovich, A; Ying, J; Yokkaichi, S; You, Z; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zolin, L

    2014-06-01

    Charged-pion-interferometry measurements were made with respect to the second- and third-order event plane for Au+Au collisions at sqrt[s_{NN}]=200  GeV. A strong azimuthal-angle dependence of the extracted Gaussian-source radii was observed with respect to both the second- and third-order event planes. The results for the second-order dependence indicate that the initial eccentricity is reduced during the medium evolution, which is consistent with previous results. In contrast, the results for the third-order dependence indicate that the initial triangular shape is significantly reduced and potentially reversed by the end of the medium evolution, and that the third-order oscillations are largely dominated by the dynamical effects from triangular flow. PMID:24949761

  10. Optical Interferometry Motivation and History

    NASA Technical Reports Server (NTRS)

    Lawson, Peter

    2006-01-01

    A history and motivation of stellar interferometry is presented. The topics include: 1) On Tides, Organ Pipes, and Soap Bubbles; 2) Armand Hippolyte Fizeau (1819-1896); 3) Fizeau Suggests Stellar Interferometry 1867; 4) Edouard Stephan (1837-1923); 5) Foucault Refractor; 6) Albert A. Michelson (1852-1931); 7) On the Application of Interference Methods to Astronomy (1890); 8) Moons of Jupiter (1891); 9) Other Applications in 19th Century; 10) Timeline of Interferometry to 1938; 11) 30 years goes by; 12) Mount Wilson Observatory; 13) Michelson's 20 ft Interferometer; 14) Was Michelson Influenced by Fizeau? 15) Work Continues in the 1920s and 30s; 16) 50 ft Interferometer (1931-1938); 17) Light Paths in the 50 ft Interferometer; 18) Ground-level at the 50 ft; 19) F.G. Pease (1881-1938); 20) Timeline of Optical Interferometry to 1970; 21) A New Type of Stellar Interferometer (1956); 22) Intensity Interferometer (1963- 1976; 23) Robert Hanbury Brown; 24) Interest in Optical Interferometry in the 1960s; 25) Interferometry in the Early 1970s; and 26) A New Frontier is Opened up in 1974.

  11. Advances in Astrometry and Geophysics Made Possible by Radio Interferometry

    NASA Astrophysics Data System (ADS)

    Johnston, Kenneth J.

    1998-01-01

    Radio Interferometry has had a tremendous impact on the development of astrometry and geodesy. Barry Clark has played a leading role in developing the technology of radio interferometry through his work on connected-element interferometry, i.e., the Green Bank Interferometer and Very Large Array; and VLBI, i.e., the Mark I and II VLBI systems and the Very Long Baseline Array (VLBA). These efforts resulted in an increase in astrometric accuracy of four orders of magnitude. Stellar positions at radio wavelengths now can be measured with a precision of 0.1 milliarcseconds (mas). Earth orientation parameters such as UT1 and polar motion are now measured with precisions of 10 microarcseconds (micronas). The precession constants and models for nutation need revision to precisions at the microarcsecond level. Tectonic plate motion was directly measured in the 1980s. These were and are exciting times for research in these fields and Barry's scientific career parallels them especially in astrometry.

  12. Neutron interferometry with cold stage

    NASA Astrophysics Data System (ADS)

    Mineeva, Taisiya; Arif, M.; Huber, M. G.; Shahi, C. B.; Clark, C. W.; Cory, D. G.; Nsofini, J.; Sarenac, D.; Pushin, D. A.

    Neutron interferometry (NI) is amongst the most precise methods for characterizing neutron interactions by measuring the relative difference between two neutron paths, one of which contains a sample-of-interest. Because neutrons carry magnetic moment and are deeply penetrating, they are excellent probes to investigate properties of magnetic materials. The advantage of NI is its unique sensitivity which allows to directly measure magnetic and structural transitions in materials. Up to now NI has been sparingly used in material research due to its sensitivity to environmental noise. However, recent successes in implementing Quantum Error Correction principles lead to an improved NI design making it robust against mechanical vibrations. Following these advances, a new user facility at the National Institute for Standards and Technology was built to study condensed matter applications, biology and quantum physics. Incorporating cold sample stage inside NI is the first of its kind experiment which can be carried out on large range of temperatures down to 4K. Upon successful realization, it will open new frontiers to characterize magnetic domains, phase transitions and spin properties in a variety of materials such as, for example, iron-based superconductors and spintronic materials. Supported in part by CERC, CIFAR, NSERC and CREATE.

  13. Resolving microstructures in Z pinches with intensity interferometry

    SciTech Connect

    Apruzese, J. P.; Kroupp, E.; Maron, Y.; Giuliani, J. L.; Thornhill, J. W.

    2014-03-15

    Nearly 60 years ago, Hanbury Brown and Twiss [R. Hanbury Brown and R. Q. Twiss, Nature 178, 1046 (1956)] succeeded in measuring the 30 nrad angular diameter of Sirius using a new type of interferometry that exploited the interference of photons independently emitted from different regions of the stellar disk. Its basis was the measurement of intensity correlations as a function of detector spacing, with no beam splitting or preservation of phase information needed. Applied to Z pinches, X pinches, or laser-produced plasmas, this method could potentially provide spatial resolution under one micron. A quantitative analysis based on the work of Purcell [E. M. Purcell, Nature 178, 1449 (1956)] reveals that obtaining adequate statistics from x-ray interferometry of a Z-pinch microstructure would require using the highest-current generators available. However, using visible light interferometry would reduce the needed photon count and could enable its use on sub-MA machines.

  14. Precision optical interferometry in space

    NASA Technical Reports Server (NTRS)

    Reasenberg, Robert D.

    1993-01-01

    POINTS, an astrometric Optical interferometer with a nominal measurement accuracy of 5 microarcseconds for the angle between a pair of stars separated by about 90 deg, is presently under consideration by two divisions of NASA-OSSA. It will be a powerful new multi-disciplinary tool for astronomical research. If chosen as the TOPS-1 (Toward Other Planetary Systems) instrument by the Solar-System Exploration Division, it will perform a definitive search for extra-solar planetary systems, either finding and characterizing a large number of them or showing that they are far less numerous than now believed. If chosen as the AIM (Astrometric Interferometry Mission) by the Astrophysics Division, POINTS will open new areas of astrophysical research and change the nature of the questions being asked in some old areas. In either case. it will be the first of a new class of powerful instruments in space and will prove the technology for the larger members of that class to follow. Based on a preliminary indication of the observational needs of the two missions, we find that a single POINTS mission will meet the science objectives of both TOPS-1 and AIM. The instrument detects dispersed fringe (channel led spectrum) and therefore can tolerate large pointing errors.

  15. Structural influences on intensity interferometry

    NASA Astrophysics Data System (ADS)

    Maji, Arup; Harris, Mark

    2016-01-01

    Intensity interferometry (II) is an alternate form of creating images of distant objects. It is significantly less sensitive to atmospheric distortions and aberrations of telescope surfaces than conventional amplitude-based imaging. The deficiencies of II can be overcome as photodetectors' read-out rates are becoming faster and computers more powerful. In recognition of the possibility of very large space-based imaging systems, this paper investigates how the deformation of a large, thin optical surface would influence the accuracy of II. Based on the theoretical foundation of II, an optical ray-tracing algorithm was used to examine how the statistics of a photon stream changes from the source to the detector. Ray-tracing and finite element analyses of the structure were thereafter integrated to quantify how the correlation of the intensity field changes as the reflective structure deforms. Varying the positions of the detector from the focal plane and the surface profile of the mirror provided an understanding and quantification of how the various scenarios affect the statistics of the detected light and the correlation measurement. This research and analysis provide the means to quantify how structural perturbations of focal mirrors affect the statistics of photon stream detections inherent in II instrumentation.

  16. Nanoscale defect detection by heterodyne interferometry

    SciTech Connect

    Lin Haoshan; Li Yuhe; Wang Dongsheng; Tong Xiaolei; Liu Mei

    2009-03-10

    We construct an instrument that facilitates the measurement of nanoscale defects. It is based on heterodyne interferometry with phase measurement that utilizes a polarizing beam splitter to form a measuring signal and an oscillating cantilever tip that acts as a scanning probe to get the measurement values of sample topography. The dependence of the tip displacement on the variation of tip-sample distance and the comb scanning of the sample topography are investigated by experiments. The results prove that the tip displacement increases and is enough to be discriminated in various positions where the sample is approached. The system has been successfully utilized to measure the defect characterization by measuring the pitch of the standard sample. The results also show that the heterodyne system has good repeatability, a large measurement range, and high accuracy, with a measurement stability of 0.5 nm.

  17. Temperature measurement of axisymmetric partially premixed methane/air flame in a co-annular burner using Mach-Zehnder interferometry

    NASA Astrophysics Data System (ADS)

    Irandoost, M. S.; Ashjaee, M.; Askari, M. H.; Ahmadi, S.

    2015-11-01

    In this paper partially premixed laminar methane/air co-flow flame is studied experimentally. Methane-air flame is established on an axisymmetric co-annular burner. The fuel-air jet flows from the central tube while the secondary air flows from the region between the inner and the outer tube. The aim is to investigate the flame characteristics for methane/air axisymmetric partially premixed flame using Mach-Zehnder interferometry. Different equivalence ratios (φ=1.4-2.2) and Reynolds numbers (Re=100-1200) are considered in the study. Flame generic visible appearance and the corresponding fringe map structures are also investigated. It is seen that the fringe maps are poorly influenced by equivalence ratio variations at constant Reynolds number but are significantly affected by Reynolds number variations in constant equivalence ratio. Temperatures obtained from optical techniques are compared with those obtained from thermocouples and good agreement is observed. It is concluded that the effect of Reynolds number increment on maximum flame temperature is negligible while equivalence ratio reduction increases maximum flame temperature substantially.

  18. Measurement of the Ultrafast Spectral Diffusion of the Optical Transition of Nitrogen Vacancy Centers in Nano-Size Diamond Using Correlation Interferometry

    NASA Astrophysics Data System (ADS)

    Wolters, Janik; Sadzak, Nikola; Schell, Andreas W.; Schröder, Tim; Benson, Oliver

    2013-01-01

    Spectral diffusion is the phenomenon of random jumps in the emission wavelength of narrow lines. This phenomenon is a major hurdle for applications of solid state quantum emitters like quantum dots, molecules, or diamond defect centers in an integrated quantum optical technology. Here, we provide further insight into the underlying processes of spectral diffusion of the zero-phonon line of single nitrogen vacancy centers in nano-size diamond by using a novel method based on photon correlation interferometry. The method works although the spectral diffusion rate is several orders of magnitude higher than the photon detection rate and thereby improves the time resolution of previous experiments with nano-size diamond by 6 orders of magnitude. We study the dependency of the spectral diffusion rate on the excitation power, temperature, and excitation wavelength under off-resonant excitation. Our results bring insight into the mechanism of spectral diffusion and suggest a strategy to increase the number of spectrally indistinguishable photons emitted by diamond nanocrystals.

  19. Measurement of the ultrafast spectral diffusion of the optical transition of nitrogen vacancy centers in nano-size diamond using correlation interferometry.

    PubMed

    Wolters, Janik; Sadzak, Nikola; Schell, Andreas W; Schröder, Tim; Benson, Oliver

    2013-01-11

    Spectral diffusion is the phenomenon of random jumps in the emission wavelength of narrow lines. This phenomenon is a major hurdle for applications of solid state quantum emitters like quantum dots, molecules, or diamond defect centers in an integrated quantum optical technology. Here, we provide further insight into the underlying processes of spectral diffusion of the zero-phonon line of single nitrogen vacancy centers in nano-size diamond by using a novel method based on photon correlation interferometry. The method works although the spectral diffusion rate is several orders of magnitude higher than the photon detection rate and thereby improves the time resolution of previous experiments with nano-size diamond by 6 orders of magnitude. We study the dependency of the spectral diffusion rate on the excitation power, temperature, and excitation wavelength under off-resonant excitation. Our results bring insight into the mechanism of spectral diffusion and suggest a strategy to increase the number of spectrally indistinguishable photons emitted by diamond nanocrystals. PMID:23383937

  20. Shaken Lattice Interferometry

    NASA Astrophysics Data System (ADS)

    Weidner, Carrie; Yu, Hoon; Anderson, Dana

    2015-05-01

    This work introduces a method to perform interferometry using atoms trapped in an optical lattice. Starting at t = 0 with atoms in the ground state of a lattice potential V(x) =V0cos [ 2 kx + ϕ(t) ] , we show that it is possible to transform from one atomic wavefunction to another by a prescribed shaking of the lattice, i.e., by an appropriately tailored time-dependent phase shift ϕ(t) . In particular, the standard interferometer sequence of beam splitting, propagation, reflection, reverse propagation, and recombination can be achieved via a set of phase modulation operations {ϕj(t) } . Each ϕj(t) is determined using a learning algorithm, and the split-step method calculates the wavefunction dynamics. We have numerically demonstrated an interferometer in which the shaken wavefunctions match the target states to better than 1 % . We carried out learning using a genetic algorithm and optimal control techniques. The atoms remain trapped in the lattice throughout the full interferometer sequence. Thus, the approach may be suitable for use in an dynamic environment. In addition to the general principles, we discuss aspects of the experimental implementation. Supported by the Office of Naval Research (ONR) and Northrop Grumman.

  1. Deflectometry challenges interferometry: the competition gets tougher!

    NASA Astrophysics Data System (ADS)

    Faber, Christian; Olesch, Evelyn; Krobot, Roman; Häusler, Gerd

    2012-09-01

    Deflectometric methods that are capable of providing full-field topography data for specular freeform surfaces have been around for more than a decade. They have proven successful in various fields of application, such as the measurement of progressive power eyeglasses, painted car body panels, or windshields. However, up to now deflectometry has not been considered as a viable competitor to interferometry, especially for the qualification of optical components. The reason is that, despite the unparalleled local sensitivity provided by deflectometric methods, the global height accuracy attainable with this measurement technique used to be limited to several microns over a field of 100 mm. Moreover, spurious reflections at the rear surface of transparent objects could easily mess up the measured signal completely. Due to new calibration and evaluation procedures, this situation has changed lately. We will give a comparative assessment of the strengths and - now partly revised - weaknesses of both measurement principles from the current perspective. By presenting recent developments and measurement examples from different applications, we will show that deflectometry is now heading to become a serious competitor to interferometry.

  2. Interferometry in the Era of Very Large Telescopes

    NASA Technical Reports Server (NTRS)

    Barry, Richard K.

    2010-01-01

    Research in modern stellar interferometry has focused primarily on ground-based observatories, with very long baselines or large apertures, that have benefited from recent advances in fringe tracking, phase reconstruction, adaptive optics, guided optics, and modern detectors. As one example, a great deal of effort has been put into development of ground-based nulling interferometers. The nulling technique is the sparse aperture equivalent of conventional coronography used in filled aperture telescopes. In this mode the stellar light itself is suppressed by a destructive fringe, effectively enhancing the contrast of the circumstellar material located near the star. Nulling interferometry has helped to advance our understanding of the astrophysics of many distant objects by providing the spatial resolution necessary to localize the various faint emission sources near bright objects. We illustrate the current capabilities of this technique by describing the first scientific results from the Keck Interferometer Nuller that combines the light from the two largest optical telescopes in the world including new, unpublished measurements of exozodiacal dust disks. We discuss prospects in the near future for interferometry in general, the capabilities of secondary masking interferometry on very large telescopes, and of nulling interferometry using outriggers on very large telescopes. We discuss future development of a simplified space-borne NIR nulling architecture, the Fourier-Kelvin Stellar Interferometer, capable of detecting and characterizing an Earth twin in the near future and how such a mission would benefit from the optical wavelength coverage offered by large, ground-based instruments.

  3. Damage Detection Using Holography and Interferometry

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.

    2003-01-01

    This paper reviews classical approaches to damage detection using laser holography and interferometry. The paper then details the modern uses of electronic holography and neural-net-processed characteristic patterns to detect structural damage. The design of the neural networks and the preparation of the training sets are discussed. The use of a technique to optimize the training sets, called folding, is explained. Then a training procedure is detailed that uses the holography-measured vibration modes of the undamaged structures to impart damage-detection sensitivity to the neural networks. The inspections of an optical strain gauge mounting plate and an International Space Station cold plate are presented as examples.

  4. Three-color differential interferometry.

    PubMed

    Desse, J M

    1997-10-01

    It is shown that differential interferometry using a Wollaston prism and a three-color laser source is an optical technique that has all the advantages of differential interferometry in polarized white light and of classical monochromatic interferometry. The interference fringe pattern obtained is very large and colored and presents a central white fringe that enables easy identification of the zero order of the interferogram. The three-color source is obtained by filtering the unwanted lines of the ionized laser (mixed argon and krypton) and balancing the three red, green, and blue lines by a technique that involves placing birefringent plates between the polarizer and the analyzer, the thickness of which has been calculated to create a natural filter. The unsteady aerodynamic flow downstream of a diamond shape airfoil has been visualized with this technique, which shows that the power of the light source is sufficient to record the interferograms at a high rate. PMID:18264221

  5. Interferometry-based Kolsky bar apparatus

    NASA Astrophysics Data System (ADS)

    Avinadav, C.; Ashuach, Y.; Kreif, R.

    2011-07-01

    A new experimental approach of the Kolsky bar system using optical interferometry is presented for determination of dynamic behavior of materials. Conventional measurements in the Kolsky bar system are based on recording the strain histories on the incident and transmitter bars with two strain gauges, and require good adhesion between the gauge and the bar. We suggest an alternative approach, based on measuring the actual velocities of the bars by using fiber-based velocity interferometry. Two fiber focusers illuminate the bars at a small angle and collect reflected Doppler-shifted light, which is interfered with a reference beam. Velocities are calculated from short-time Fourier transform and phase-based analysis, and the dynamic stress-strain curve is derived directly from the measured velocity traces. We demonstrate that the results coincide with those obtained by conventional strain gauge measurements. The new method is non-intervening and thus not affected by bar impacts, making it more robust and reliable than strain gauges.

  6. Non-Abelian Anyons and Interferometry

    NASA Astrophysics Data System (ADS)

    Bonderson, Parsa Hassan

    This thesis is primarily a study of the measurement theory of non-Abelian anyons through interference experiments. We give an introduction to the theory of anyon models, providing all the formalism necessary to apply standard quantum measurement theory to such systems. This formalism is then applied to give a detailed analysis of a Mach-Zehnder interferometer for arbitrary anyon models. In this treatment, we find that the collapse behavior exhibited by a target anyon in a superposition of states is determined by the monodromy of the probe anyons with the target. Such measurements may also be used to gain knowledge that would help to properly identify the anyon model describing an unknown system. The techniques used and results obtained from this model interferometer have general applicability, and we use them to also describe the interferometry measurements in a two point-contact interferometer proposed for non-Abelian fractional quantum Hall states. Additionally, we give the complete description of a number of important examples of anyon models, as well as their corresponding quantities that are relevant for interferometry. Finally, we give a partial classification of anyon models with small numbers of particle types.

  7. A publication database for optical long baseline interferometry

    NASA Astrophysics Data System (ADS)

    Malbet, Fabien; Mella, Guillaume; Lawson, Peter; Taillifet, Esther; Lafrasse, Sylvain

    2010-07-01

    Optical long baseline interferometry is a technique that has generated almost 850 refereed papers to date. The targets span a large variety of objects from planetary systems to extragalactic studies and all branches of stellar physics. We have created a database hosted by the JMMC and connected to the Optical Long Baseline Interferometry Newsletter (OLBIN) web site using MySQL and a collection of XML or PHP scripts in order to store and classify these publications. Each entry is defined by its ADS bibcode, includes basic ADS informations and metadata. The metadata are specified by tags sorted in categories: interferometric facilities, instrumentation, wavelength of operation, spectral resolution, type of measurement, target type, and paper category, for example. The whole OLBIN publication list has been processed and we present how the database is organized and can be accessed. We use this tool to generate statistical plots of interest for the community in optical long baseline interferometry.

  8. Modulated Source Interferometry with Combined Amplitude and Frequency Modulation

    NASA Technical Reports Server (NTRS)

    Gutierrez, Roman C. (Inventor)

    1998-01-01

    An improved interferometer is produced by modifying a conventional interferometer to include amplitude and/or frequency modulation of a coherent light source at radio or higher frequencies. The phase of the modulation signal can be detected in an interfering beam from an interferometer and can be used to determine the actual optical phase of the beam. As such, this improvement can be adapted to virtually any two-beam interferometer, including: Michelson, Mach-Zehnder, and Sagnac interferometers. The use of an amplitude modulated coherent tight source results in an interferometer that combines the wide range advantages of coherent interferometry with the precise distance measurement advantages of white light interferometry.

  9. Random phase-shifting interferometry based on independent component analysis

    NASA Astrophysics Data System (ADS)

    Xu, Xiaofei; Lu, Xiaoxu; Tian, Jindong; Shou, Junwei; Zheng, Dejin; Zhong, Liyun

    2016-07-01

    In random phase-shifting interferometry, a novel phase retrieval algorithm is proposed based on the independent component analysis (ICA). By performing the recombination of pixel position, a sequence of phase-shifting interferograms with random phase shifts are decomposed into a group of mutual independent components, and then the background and the measured phase of interferogram can obtained with a simple arctangent operation. Compared with the conventional advanced iterative algorithm (AIA) with high accuracy, both the simulation and the experimental results demonstrate that the proposed ICA algorithm reveals high accuracy, rapid convergence, and good noise-tolerance in random phase-shifting interferometry.

  10. Differential interferometry with adjustable spatial carrier fringes for turbine blade cascade flow investigations

    NASA Astrophysics Data System (ADS)

    Woisetschläger, J.; Pretzler, G.; Jericha, H.; Mayrhofer, N.; Pirker, H. P.

    Digital evaluated differential interferometry using adjustable spatial carrier fringes was applied to flow measurements in a transonic turbine blade cascade. The interferograms were evaluated using a two-dimensional Fourier Analysis. This evaluation provided density gradient maps of the flow field in a digital form. A specially designed interferometer was used allowing adjustment of sensitivity and superposition of carrier-fringe system separately. This type of interferometer is also highly insensitive to vibration noise. For a turbine blade cooling film a comparison of this type of differential interferometry with holographic interferometry and a Schlieren visualisation is also given. As a result differential interferometry using adjustable spatial carrier fringes and digital fringe analysis gave density-gradient maps similar to Schlieren recordings but of quantitative nature, thus enabling compensation of wave front distortions. Integration of these density gradient maps resulted in density maps which were then compared to recordings done with pulsed holographic interferometry.

  11. High-Speed Digital Interferometry

    NASA Technical Reports Server (NTRS)

    De Vine, Glenn; Shaddock, Daniel A.; Ware, Brent; Spero, Robert E.; Wuchenich, Danielle M.; Klipstein, William M.; McKenzie, Kirk

    2012-01-01

    Digitally enhanced heterodyne interferometry (DI) is a laser metrology technique employing pseudo-random noise (PRN) codes phase-modulated onto an optical carrier. Combined with heterodyne interferometry, the PRN code is used to select individual signals, returning the inherent interferometric sensitivity determined by the optical wavelength. The signal isolation arises from the autocorrelation properties of the PRN code, enabling both rejection of spurious signals (e.g., from scattered light) and multiplexing capability using a single metrology system. The minimum separation of optical components is determined by the wavelength of the PRN code.

  12. Polarization Effects Aboard the Space Interferometry Mission

    NASA Technical Reports Server (NTRS)

    Levin, Jason; Young, Martin; Dubovitsky, Serge; Dorsky, Leonard

    2006-01-01

    For precision displacement measurements, laser metrology is currently one of the most accurate measurements. Often, the measurement is located some distance away from the laser source, and as a result, stringent requirements are placed on the laser delivery system with respect to the state of polarization. Such is the case with the fiber distribution assembly (FDA) that is slated to fly aboard the Space Interferometry Mission (SIM) next decade. This system utilizes a concatenated array of couplers, polarizers and lengthy runs of polarization-maintaining (PM) fiber to distribute linearly-polarized light from a single laser to fourteen different optical metrology measurement points throughout the spacecraft. Optical power fluctuations at the point of measurement can be traced back to the polarization extinction ration (PER) of the concatenated components, in conjunction with the rate of change in phase difference of the light along the slow and fast axes of the PM fiber.

  13. Mask Design for the Space Interferometry Mission Internal Metrology

    NASA Technical Reports Server (NTRS)

    Marx, David; Zhao, Feng; Korechoff, Robert

    2005-01-01

    This slide presentation reviews the mask design used for the internal metrology of the Space Interferometry Mission (SIM). Included is information about the project, the method of measurements with SIM, the internal metrology, numerical model of internal metrology, wavefront examples, performance metrics, and mask design

  14. Waveguide Zeeman interferometry for thin-film chemical sensors

    SciTech Connect

    Grace, K.M.; Shrouf, K.; Johnston, R.G.; Yang, X.; Swanson, B.; Honkanen, S.; Ayras, P.; Peyghambarian, N.; Katila, P.; Leppihalme, M.

    1997-10-01

    A chemical sensor is demonstrated which is based on Si{sub 3}N{sub 4} optical waveguides coated with species-selective thin films and using Zeeman interferometry as the detection technique. Relative phase change between TE and TM modes is measured. Real time and reversible response to toluene is shown with ppm level sensitivity.

  15. Soft x-ray interferometry

    SciTech Connect

    Not Available

    1993-09-01

    The purpose of the soft x-ray interferometry workshop held at Lawrence Berkeley Laboratory was to discuss with the scientific community the proposed technical design of the soft x-ray Fourier-transform spectrometer being developed at the ALS. Different design strategies for the instrument`s components were discussed, as well as detection methods, signal processing issues, and how to meet the manufacturing tolerances that are necessary for the instrument to achieve the desired levels of performance. Workshop participants were encouraged to report on their experiences in the field of Fourier transform spectroscopy. The ALS is developing a Fourier transform spectrometer that is intended to operate up to 100 eV. The motivation is solely improved resolution and not the throughput (Jaquinot) or multiplex (Fellgett) advantage, neither of which apply for the sources and detectors used in this spectral range. The proposed implementation of this is via a Mach-Zehnder geometry that has been (1) distorted from a square to a rhombus to get grazing incidence of a suitable angle for 100 eV and (2) provided with a mirror-motion system to make the path difference between the interfering beams tunable. The experiment consists of measuring the emergent light intensity (I(x)) as a function of the path difference (x). The resolving power of the system is limited by the amount of path difference obtainable that is 1 cm (one million half-waves at 200{angstrom} wavelength) in the design thus allowing a resolving power of one million. The free spectral range of the system is limited by the closeness with which the function I(x) is sampled. It is proposed to illuminate a helium absorption cell with roughly 1%-band-width light from a monochromator thus allowing one hundred aliases without spectral overlap even for sampling of I(x) at one hundredth of the Nyquist frequency.

  16. Industrial laser interferometry II; Proceedings of the Meeting, Dearborn, MI, June 27, 28, 1988

    SciTech Connect

    Hung, M.Y.Y.; Pryputniewicz, R.

    1988-01-01

    Various papers on industrial laser interferometry are presented. Individual topics discussed include: specklegrammetry for precision surface coordinate measurement, fast detection of residual stresses by shearography, surface inspection of automotive bodies by reflective computer vision, shearographic detection of flaws in unity vision optical components, coherent information process of white light speckle sandwich, coherent sensors for hostile environments, and grating method for strain measurement. Also considered are: Talbot carrier image processing of birefringence effect, advancement in photocarrier Talbot effect theory, shearing photoelasticity, study of brake squeal problem by pulsed holographic interferometry, modeling of drill bit transverse vibrations, use of glass fiber techniques in holographic deformation analysis, and vibration studies using heterodyne hologram interferometry.

  17. Seismic interferometry by multidimensional deconvolution without wavefield separation

    NASA Astrophysics Data System (ADS)

    Ravasi, Matteo; Meles, Giovanni; Curtis, Andrew; Rawlinson, Zara; Yikuo, Liu

    2015-07-01

    Seismic interferometry comprises a suite of methods to redatum recorded wavefields to those that would have been recorded if different sources (so-called virtual sources) had been activated. Seismic interferometry by cross-correlation has been formulated using either two-way (for full wavefields) or one-way (for directionally decomposed wavefields) representation theorems. To obtain improved Green's function estimates, the cross-correlation result can be deconvolved by a quantity that identifies the smearing of the virtual source in space and time, the so-called point-spread function. This type of interferometry, known as interferometry by multidimensional deconvolution (MDD), has so far been applied only to one-way directionally decomposed fields, requiring accurate wavefield decomposition from dual (e.g. pressure and velocity) recordings. Here we propose a form of interferometry by multidimensional deconvolution that uses full wavefields with two-way representations, and simultaneously invert for pressure and (normal) velocity Green's functions, rather than only velocity responses as for its one-way counterpart. Tests on synthetic data show that two-way MDD improves on results of interferometry by cross-correlation, and generally produces estimates of similar quality to those obtained by one-way MDD, suggesting that the preliminary decomposition into up- and downgoing components of the pressure field is not required if pressure and velocity data are jointly used in the deconvolution. We also show that constraints on the directionality of the Green's functions sought can be added directly into the MDD inversion process to further improve two-way multidimensional deconvolution. Finally, as a by-product of having pressure and particle velocity measurements, we adapt one- and two-way representation theorems to convert any particle velocity receiver into its corresponding virtual dipole/gradient source by means of MDD. Thus data recorded from standard monopolar (e

  18. Meteorology Gauges for Spatial Interferometry

    NASA Technical Reports Server (NTRS)

    Gursel, Y.

    1996-01-01

    Heterodyne interferometers have been commercially available for many years. In addition, many versions have been built at JPL for various projects. This activity is aimed at improving the accuracy of such interferometers from the 1-30 nanometer level to the picometer level for use in the proposes Stellar Interferometry Mission (SIM) as metrology gauges.

  19. Ultrafast electrooptic dual-comb interferometry.

    PubMed

    Durán, Vicente; Tainta, Santiago; Torres-Company, Victor

    2015-11-16

    Dual-comb interferometry is a particularly compelling technique that relies on the phase coherence of two laser frequency combs for measuring broadband complex spectra. This method is rapidly advancing the field of optical spectroscopy and empowering new applications, from nonlinear microscopy to laser ranging. Up to now, most dual-comb interferometers were based on modelocked lasers, whose repetition rates have restricted the measurement speed to ~kHz. Here we demonstrate a dual-comb interferometer that is based on electrooptic frequency combs and measures consecutive complex spectra at an ultra-high refresh rate of 25 MHz. These results pave the way for novel scientific and metrology applications of frequency comb generators beyond the realm of molecular spectroscopy, where the measurement of ultrabroadband waveforms is of paramount relevance. PMID:26698533

  20. Is Space-based Interferometry Dead?

    NASA Astrophysics Data System (ADS)

    Leisawitz, David; Benford, D.; Blain, A.; Carr, J.; Fich, M.; Fischer, J.; Goldsmith, P.; Greaves, J.; Griffin, M.; Helou, G.; Ivison, R.; Kuchner, M.; Lyon, R.; Matsuo, H.; Rinehart, S. A.; Serabyn, E.; Shibai, H.; Silverberg, R.; Staguhn, J.; Unwin, S.; Wilner, D.; Wootten, A.; Wright, E. L.

    2011-05-01

    In the wake of the Decadal Survey and a January 2011 meeting of NASA's Exoplanet Exploration Program Analysis Group (ExoPAG), one might be tempted to conclude that space interferometry is dead. We explain why this slogan is hyperbole, summarize the steps currently being taken to prepare for a space-based far-IR interferometer, and reiterate the science case for an imaging and spectroscopic interferometer - SPIRIT - that would operate in space at long infrared wavelengths. Space-based interferometry is alive and well, but the center of activity has shifted to a spectral region (25 to 400 microns) in which no alternative measurement technique can provide information essential to answering several scientific questions deemed compelling by the Decadal Survey. Astrophysicists will use SPIRIT to: discover how the conditions for habitability arise during planetary system formation; find and characterize exoplanets by measuring their sculpting effects on protoplanetary and debris disks; and study the formation, merger history, and star formation history of galaxies.

  1. Refractive index determination by coherence scanning interferometry.

    PubMed

    Yoshino, H; Kaminski, P M; Smith, R; Walls, J M; Mansfield, D

    2016-05-20

    Coherence scanning interferometry is established as a powerful noncontact, three-dimensional, metrology technique used to determine accurate surface roughness and topography measurements with subnanometer precision. The helical complex field (HCF) function is a topographically defined helix modulated by the electrical field reflectance, originally developed for the measurement of thin films. An approach to extend the capability of the HCF function to determine the spectral refractive index of a substrate or absorbing film has recently been proposed. In this paper, we confirm this new capability, demonstrating it on surfaces of silicon, gold, and a gold/palladium alloy using silica and zirconia oxide thin films. These refractive index dispersion measurements show good agreement with those obtained by spectroscopic ellipsometry. PMID:27411157

  2. Beam-modulation methods in quantitative and flow-visualization holographic interferometry

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.

    1986-01-01

    Heterodyne holographic interferometry and time-average holography with a frequency shifted reference beam are discussed. Both methods will be used for the measurement and visualization of internal transonic flows where the target facility is a flutter cascade. The background and experimental requirements for both methods are reviewed. Measurements using heterodyne holographic interferometry are presented. The performance of the laser required for time-average holography of time-varying transonic flows is discussed.

  3. Beam-modulation methods in quantitative and flow visualization holographic interferometry

    NASA Technical Reports Server (NTRS)

    Decker, A.

    1986-01-01

    This report discusses heterodyne holographic interferometry and time-average holography with a frequency shifted reference beam. Both methods will be used for the measurement and visualization of internal transonic flows, where the target facility is a flutter cascade. The background and experimental requirements for both methods are reviewed. Measurements using heterodyne holographic interferometry are presented. The performance of the laser required for time-average holography of time-varying transonic flows is discussed.

  4. Interferometry using undulator sources (invited, abstract)

    NASA Astrophysics Data System (ADS)

    Beguiristain, R.; Goldberg, K. A.; Tejnil, E.; Bokor, J.; Medecki, H.; Attwood, D. T.; Jackson, K.

    1996-09-01

    Optical systems for extreme ultraviolet (EUV) lithography need to use optical components with subnanometer surface figure error tolerances to achieve diffraction-limited performance [M.D. Himel, in Soft X-Ray Projection Lithography, A.M. Hawryluk and R.H. Stulen, eds. (OSA, Washington, D.C., 1993), 18, 1089, and D. Attwood et al., Appl. Opt. 32, 7022 (1993)]. Also, multilayer-coated optics require at-wavelength wavefront measurement to characterize phase effects that cannot be measured by conventional optical interferometry. Furthermore, EUV optical systems will additionally require final testing and alignment at the operational wavelength for adjustment and reduction of the cumulative optical surface errors. Therefore, at-wavelength interferometric measurement of EUV optics will be the necessary metrology tool for the successful development of optics for EUV lithography. An EUV point diffraction interferometer (PDI) has been developed at the Center for X-Ray Optics (CXRO) and has been already in operation for a year [K. Goldberg et al., in Extreme Ultra Lithography, D.T. Attwood and F. Zernike, eds. (OSA, Washington, D.C., 1994), K. Goldberg et al., Proc. SPIE 2437, to be published, and K. Goldberg et al., J. Vac. Sci. Technol. B 13, 2923 (1995)] using an undulator radiation source and coherent optics beamline at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. An overview of the PDI interferometer and some EUV wavefront measurements obtained with this instrument will be presented. In addition, future developments planned for EUV interferometry at CXRO towards the measurement of actual EUV lithography optics will be shown.

  5. Optical and Infrared Interferometry IV

    NASA Astrophysics Data System (ADS)

    Rajagopal, Jayadev K.; Creech-Eakman, Michelle J.; Malbet, Fabien

    2014-08-01

    Optical and IR Interferometry IV at the SPIE 2014 symposium in Montreal had a strong and vibrant program. After initial fears about budget cuts and travel-funding constraints, the Program Committee had to work hard to accommodate as many quality submissions as possible. Innovative, creative and visionary work ensured that the field has progressed well, despite the bleak funding climate felt in the US, Europe and elsewhere. Montreal proved an excellent venue for this, the largest of Interferometry conferences and the only one that brings together practitioners from the world over. Let us summarize a few highlights to convey a glimpse of the excitement that is detailed in the rest of these Proceedings.

  6. Precision Geodesy via Radio Interferometry.

    PubMed

    Hinteregger, H F; Shapiro, I I; Robertson, D S; Knight, C A; Ergas, R A; Whitney, A R; Rogers, A E; Moran, J M; Clark, T A; Burke, B F

    1972-10-27

    Very-long-baseline interferometry experiments, involving observations of extragalactic radio sources, were performed in 1969 to determine the vector separations between antenna sites in Massachusetts and West Virginia. The 845.130-kilometer baseline was estimated from two separate experiments. The results agreed with each other to within 2 meters in all three components and with a special geodetic survey to within 2 meters in length; the differences in baseline direction as determined by the survey and by interferometry corresponded to discrepancies of about 5 meters. The experiments also yielded positions for nine extragalactic radio sources, most to within 1 arc second, and allowed the hydrogen maser clocks at the two sites to be synchronized a posteriori with an uncertainty of only a few nanoseconds. PMID:17815361

  7. Sagnac Interferometry with a Single Atomic Clock.

    PubMed

    Stevenson, R; Hush, M R; Bishop, T; Lesanovsky, I; Fernholz, T

    2015-10-16

    The Sagnac effect enables interferometric measurements of rotation with high precision. Using matter waves instead of light promises resolution enhancement by orders of magnitude that scales with particle mass. So far, the paradigm for matter wave Sagnac interferometry relies on de Broglie waves and thus on free propagation of atoms either in free fall or within waveguides. However, the Sagnac effect can be expressed as a proper time difference experienced by two observers moving in opposite directions along closed paths and has indeed been measured with atomic clocks flown around Earth. Inspired by this, we investigate an interferometer comprised of a single atomic clock. The Sagnac effect manifests as a phase shift between trapped atoms in different internal states after transportation along closed paths in opposite directions, without any free propagation. With analytic models, we quantify limitations of the scheme arising from atomic dynamics and finite temperature. Furthermore, we suggest an implementation with previously demonstrated technology. PMID:26550871

  8. Sagnac Interferometry with a Single Atomic Clock

    NASA Astrophysics Data System (ADS)

    Stevenson, R.; Hush, M. R.; Bishop, T.; Lesanovsky, I.; Fernholz, T.

    2015-10-01

    The Sagnac effect enables interferometric measurements of rotation with high precision. Using matter waves instead of light promises resolution enhancement by orders of magnitude that scales with particle mass. So far, the paradigm for matter wave Sagnac interferometry relies on de Broglie waves and thus on free propagation of atoms either in free fall or within waveguides. However, the Sagnac effect can be expressed as a proper time difference experienced by two observers moving in opposite directions along closed paths and has indeed been measured with atomic clocks flown around Earth. Inspired by this, we investigate an interferometer comprised of a single atomic clock. The Sagnac effect manifests as a phase shift between trapped atoms in different internal states after transportation along closed paths in opposite directions, without any free propagation. With analytic models, we quantify limitations of the scheme arising from atomic dynamics and finite temperature. Furthermore, we suggest an implementation with previously demonstrated technology.

  9. Molecular wave packet interferometry and quantum entanglement

    NASA Astrophysics Data System (ADS)

    Martínez-Galicia, Ricardo; Romero-Rochín, Víctor

    2005-03-01

    We study wave packet interferometry (WPI) considering the laser pulse fields both classical and quantum mechanically. WPI occurs in a molecule after subjecting it to the interaction with a sequence of phase-locked ultrashort laser pulses. Typically, the measured quantity is the fluorescence of the molecule from an excited electronic state. This signal has imprinted the interference of the vibrational wave packets prepared by the different laser pulses of the sequence. The consideration of the pulses as quantum entities in the analysis allows us to study the entanglement of the laser pulse states with the molecular states. With a simple model for the molecular system, plus several justified approximations, we solve for the fully quantum mechanical molecule-electromagnetic field state. We then study the reduced density matrices of the molecule and the laser pulses separately. We calculate measurable corrections to the case where the fields are treated classically.

  10. Meson interferometry in relativistic heavy ion collisions

    SciTech Connect

    Not Available

    1993-05-01

    This report contains discussions on the following topics: Recent HBT results form CERN experiment NA44; interferometry results from E802/E859/E866; recent results on two particle correlations from E814; source sizes from CERN data; intermittency and interferometry; Bose-Einstein correlations in 200A GeV S+Au collisions; HBT correlations at STAR; HBT interferometry with PHENIX; HBT calculations from ARC; three pion correlations; and pion correlations in proton-induced reactions.

  11. A new polarized neutron interferometry facility at the NCNR

    NASA Astrophysics Data System (ADS)

    Shahi, C. B.; Arif, M.; Cory, D. G.; Mineeva, T.; Nsofini, J.; Sarenac, D.; Williams, C. J.; Huber, M. G.; Pushin, D. A.

    2016-03-01

    A new monochromatic beamline and facility has been installed at the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) devoted to neutron interferometry in the research areas of spin control, spin manipulation, quantum mechanics, quantum information science, spintronics, and material science. This facility is possible in part because of advances in decoherence free subspace interferometer designs that have demonstrated consistent contrast in the presence of vibrational noise; a major environmental constraint that has prevented neutron interferometry from being applied at other neutron facilities. Neutron interferometry measures the phase difference between a neutron wave function propagating along two spatially separated paths. It is a practical example of self interference and due to its modest path separation of a few centimeters allows the insertion of samples and macroscopic neutron spin rotators. Phase shifts can be caused by gravitational, magnetic and nuclear interactions as well as purely quantum mechanical effects making interferometer a robust tool in neutron research. This new facility is located in the guide hall of the NCNR upstream of the existing Neutron Interferometry and Optics Facility (NIOF) and has several advantages over the NIOF including higher incident flux, better neutron polarization, and increased accessibility. The long term goal for the new facility is to be a user supported beamline and makes neutron interferometer more generally available to the scientific community. This paper addresses both the capabilities and characteristics of the new facility.

  12. Geometric Landau-Zener interferometry.

    PubMed

    Gasparinetti, S; Solinas, P; Pekola, J P

    2011-11-11

    We propose a new type of interferometry, based on geometric phases accumulated by a periodically driven two-level system undergoing multiple Landau-Zener transitions. As a specific example, we study its implementation in a superconducting charge pump. We find that interference patterns appear as a function of the pumping frequency and the phase bias, and clearly manifest themselves in the pumped charge. We also show that the effects described should persist in the presence of realistic decoherence. PMID:22181761

  13. Special topics in infrared interferometry. [Michelson interferometer development

    NASA Technical Reports Server (NTRS)

    Hanel, R. A.

    1985-01-01

    Topics in IR interferometry related to the development of a Michelson interferometer are treated. The selection and reading of the signal from the detector to the analog to digital converter is explained. The requirements for the Michelson interferometer advance speed are deduced. The effects of intensity modulation on the interferogram are discussed. Wavelength and intensity calibration of the interferometer are explained. Noise sources (Nyquist or Johnson noise, phonon noise), definitions of measuring methods of noise, and noise measurements are presented.

  14. Prism-pair interferometry by homodyne interferometers with a common light source for high-accuracy measurement of the absolute refractive index of glasses

    SciTech Connect

    Hori, Yasuaki; Hirai, Akiko; Minoshima, Kaoru

    2011-03-10

    A prism-pair interferometer comprising two homodyne interferometers with a common light source was developed for high-precision measurements of the refractive index of optical glasses with an uncertainty of the order of 10{sup -6}. The two interferometers measure changes in the optical path length in the glass sample and in air, respectively. Uncertainties in the absolute wavelength of the common light source are cancelled out by calculating a ratio between the results from the interferometers. Uncertainties in phase measurement are suppressed by a quadrature detection system. The combined standard uncertainty of the developed system is evaluated as 1.1x10{sup -6}.

  15. Quadrature wavelength scanning interferometry.

    PubMed

    Moschetti, Giuseppe; Forbes, Alistair; Leach, Richard K; Jiang, Xiang; O'Connor, Daniel

    2016-07-10

    A novel method to double the measurement range of wavelength scanning interferometery (WSI) is described. In WSI the measured optical path difference (OPD) is affected by a sign ambiguity, that is, from an interference signal it is not possible to distinguish whether the OPD is positive or negative. The sign ambiguity can be resolved by measuring an interference signal in quadrature. A method to obtain a quadrature interference signal for WSI is described, and a theoretical analysis of the advantages is reported. Simulations of the advantages of the technique and of signal errors due to nonideal quadrature are discussed. The analysis and simulation are supported by experimental measurements to show the improved performances. PMID:27409307

  16. Hanbury Brown and Twiss interferometry with interacting photons

    NASA Astrophysics Data System (ADS)

    Bromberg, Y.; Lahini, Y.; Small, E.; Silberberg, Y.

    2010-10-01

    Five decades ago, Hanbury Brown and Twiss (HBT) demonstrated that the angular size of stars can be measured by correlating the intensity fluctuations measured by two detectors at two different locations. Since then, non-local correlation measurements have become ubiquitous in many areas of physics and have also been applied, beyond photons, to electrons, matter waves and subatomic particles. An important assumption in HBT interferometry is that the particles do not interact on their way from the source to the detectors. However, this assumption is not always valid. Here, we study the effects of interactions on HBT interferometry by considering the propagation of light fields in a nonlinear medium that induces interactions between the photons. We show that interactions affect multipath interference, limiting the ability to extract information on the source. Nevertheless, we find that proper analysis of the intensity fluctuations can recover the size of the source, even in the presence of interactions.

  17. Optical Distortion Evaluation in Large Area Windows using Interferometry

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C.; Skow, Miles; Nurge, Mark A.

    2015-01-01

    It is important that imagery seen through large area windows, such as those used on space vehicles, not be substantially distorted. Many approaches are described in the literature for measuring the distortion of an optical window, but most suffer from either poor resolution or processing difficulties. In this paper a new definition of distortion is presented, allowing accurate measurement using an optical interferometer. This new definition is shown to be equivalent to the definitions provided by the military and the standards organizations. In order to determine the advantages and disadvantages of this new approach the distortion of an acrylic window is measured using three different methods; image comparison, Moiré interferometry, and phase-shifting interferometry.

  18. Holographic Interferometry based on photorefractive crystal to measure 3D thermo-elastic distortion of composite structures and comparison with finite element models

    NASA Astrophysics Data System (ADS)

    Thizy, C.; Eliot, F.; Ballhause, D.; Olympio, K. R.; Kluge, R.; Shannon, A.; Laduree, G.; Logut, D.; Georges, M. P.

    2013-04-01

    Thermo-elastic distortions of composite structures have been measured by a holographic camera using a BSO photorefractive crystal as the recording medium. The first test campaign (Phase 1) was performed on CFRP struts with titanium end-fittings glued to the tips of the strut. The samples were placed in a vacuum chamber. The holographic camera was located outside the chamber and configured with two illuminations to measure the relative out-of-plane and in-plane (in one direction) displacements. The second test campaign (Phase 2) was performed on a structure composed of a large Silicon Carbide base plate supported by 3 GFRP struts with glued Titanium end-fittings. Thermo-elastic distortions have been measured with the same holographic camera used in phase 1, but four illuminations, instead of two, have been used to provide the three components of displacement. This technique was specially developed and validated during the phase 2 in CSL laboratory. The system has been designed to measure an object size of typically 250x250 mm2; the measurement range is such that the sum of the largest relative displacements in the three measurement directions is maximum 20 μm. The validation of the four-illuminations technique led to measurement uncertainties of 120 nm for the relative in-plane and out-of-plane displacements, 230 nm for the absolute in-plane displacement and 400 nm for the absolute out-of-plane displacement. For both campaigns, the test results have been compared to the predictions obtained by finite element analyses and the correlation of these results was good.

  19. Application of Seismic Interferometry to Natural Earthquake Records

    NASA Astrophysics Data System (ADS)

    Torii, K.; Matsuoka, T.; Aizawa, T.

    2007-12-01

    Recently, seismic interferometry has been one of the hottest topics in the exploration geophysics since this can be applied to reflection seismology. Seismic interferometry constructs Green's functions between arbitrary two points by taking cross-correlation of records observed at two locations. These Green's functions correspond to the wavefields as if an impulsive source was set at one location and seismic wave propagates from this source to the other receiver. Therefore, if we chose two surface receivers, we can reconstruct reflection seismic data. In case of using many receivers in a survey line, taking cross-correlation of all observed data at receivers generates pseudo shot-gather data for arbitrary locations. This technique does not need information of time 0 as long as all receivers measure wavefields synchronously. Therefore, there is no limitation with regard to the cause of the seismic vibrations. Natural earthquakes may be very good seismic sources for seismic interferometry. In our study, we adopt data provided by Hi-net system for applications of seismic interferometry. In 1995, 'The Great Hanshin Earthquake' struck around Osaka and Kobe in Japan. After that, Japanese Government decided to construct high-density and high-sensitivity sensor network all over Japan in order to accumulate effective information of earthquakes and understand the mechanism of earthquakes. This seismic network is called 'Hi- net system' in Japan. Hi-net system provides us much effective information, origin time, epicenter, depth, magnitude and waveform, etc... We used waveforms provided by Hi-net and generated pseudo shot-gather data by using seismic interferometry. Then, we applied these data to conventional reflection survey and analyzed underground structures in Japan.

  20. Polarizing phase shifting interferometry of total internal reflection light for measurement of refractive index and its spatial variation in liquid samples

    NASA Astrophysics Data System (ADS)

    Das, Tania; Bhattacharya, Kallol

    2016-07-01

    It is well known that the phase change in total internal reflection (TIR) is a function of the refractive indices of the pair of media involved. The spatial phase variations in a totally internally reflected beam are accurately measured using a Mach Zehnder interferometer employing polarization phase shifting technique. The evaluated phase change is then related to the refractive index variations of the rarer medium. One of the salient features of the proposed technique is that, unlike most interferometric methods where the measured phase is a function of the sample thickness, TIR phase is independent of the sample thickness as long as the evanescent wave field is fully confined within the sample. The theory of the technique is discussed and experimental results showing the three-dimensional profiles of the measured refractive indices and its spatial variations are presented.

  1. Shell deformation studies using holographic interferometry

    NASA Technical Reports Server (NTRS)

    Parmerter, R. R.

    1974-01-01

    The buckling of shallow spherical shells under pressure has been the subject of many theoretical and experimental papers. Experimental data above the theoretical buckling load of Huang have given rise to speculation that shallow shell theory may not adequately predict the stability of nonsymmetric modes in higher-rise shells which are normally classified as shallow by the Reissner criterion. This article considers holographic interferometry as a noncontact, high-resolution method of measuring prebuckling deformations. Prebuckling deformations of a lambda = 9, h/b = 0.038 shell are Fourier-analyzed. Buckling is found to occur in an N = 5 mode as predicted by Huang's theory. The N = 4 mode was unusually stable, suggesting that even at this low value of h/b, stabilizing effects may be at work.

  2. Confocal simultaneous phase-shifting interferometry

    SciTech Connect

    Zhao Chenguang; Tan Jiubin; Tang Jianbo; Liu Tao; Liu Jian

    2011-02-10

    In order to implement the ultraprecise measurement with large range and long working distance in confocal microscopy, confocal simultaneous phase-shifting interferometry (C-SPSI) has been presented. Four channel interference signals, with {pi}/2 phase shift between each other, are detected simultaneously in C-SPSI. The actual surface height is then calculated by combining the optical sectioning with the phase unwrapping in the main cycle of the interference phase response, and the main cycle is determined using the bipolar property of differential confocal microscopy. Experimental results showed that 1 nm of axial depth resolution was achieved for either low- or high-NA objective lenses. The reflectivity disturbance resistibility of C-SPSI was demonstrated by imaging a typical microcircuit specimen. C-SPSI breaks through the restriction of low NA on the axial depth resolution of confocal microscopy effectively.

  3. Low Coherence Interferometry in Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Neef, A.; Seyda, V.; Herzog, D.; Emmelmann, C.; Schönleber, M.; Kogel-Hollacher, M.

    Selective Laser Melting (SLM) is an additive layer manufacturing technology that offers several advantages compared to conven- tional methods of production such as an increased freedom of design and a toolless production suited for variable lot sizes. Despite these attractive aspects today's state of the art SLM machines lack a holistic process monitoring system that detects and records typical defects during production. A novel sensor concept based on the low coherence interferometry (LCI) was integrated into an SLM production setup. The sensor is mounted coaxially to the processing laser beam and is capable of sampling distances along the optical axis. Measurements during and between the processing of powder layers can reveal crucial topology information which is closely related to the final part quality. The overall potential of the sensor in terms of quality assurance and process control is being discussed. Furthermore fundamental experiments were performed to derive the performance of the system.

  4. Externally Dispersed Interferometry for Precision Radial Velocimetry

    SciTech Connect

    Erskine, D J; Muterspaugh, M W; Edelstein, J; Lloyd, J; Herter, T; Feuerstein, W M; Muirhead, P; Wishnow, E

    2007-03-27

    Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic spectral comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. The moire pattern shifts in phase in response to a Doppler shift. Moire patterns are broader than the underlying spectral features and more easily survive spectrograph blurring and common distortions. Thus, the EDI technique allows lower resolution spectrographs having relaxed optical tolerances (and therefore higher throughput) to return high precision velocity measurements, which otherwise would be imprecise for the spectrograph alone.

  5. Self-calibrating common-path interferometry.

    PubMed

    Porras-Aguilar, Rosario; Falaggis, Konstantinos; Ramirez-San-Juan, Julio C; Ramos-Garcia, Ruben

    2015-02-01

    A quantitative phase measuring technique is presented that estimates the object phase from a series of phase shifted interferograms that are obtained in a common-path configuration with unknown phase shifts. The derived random phase shifting algorithm for common-path interferometers is based on the Generalized Phase Contrast theory [pl. Opt.40(2), 268 (2001)10.1063/1.1404846], which accounts for the particular image formation and includes effects that are not present in two-beam interferometry. It is shown experimentally that this technique can be used within common-path configurations employing nonlinear liquid crystal materials as self-induced phase filters for quantitative phase imaging without the need of phase shift calibrations. The advantages of such liquid crystal elements compared to spatial light modulator based solutions are given by the cost-effectiveness, self-alignment, and the generation of diminutive dimensions of the phase filter size, giving unique performance advantages. PMID:25836191

  6. Integrating Mach-Zehnder interferometry with TPIV to measure the time-resolved deformation of a compliant wall along with the 3D velocity field in a turbulent channel flow

    NASA Astrophysics Data System (ADS)

    Zhang, Cao; Miorini, Rinaldo; Katz, Joseph

    2015-11-01

    A system combining tomographic PIV (TPIV) and Mach-Zehnder interferometry (MZI) simultaneously measures the time- resolved 3D flow field and 2D distribution of wall-normal deformation in a turbulent channel flow over a transparent compliant surface. This paper focuses on the experimental techniques and data analysis procedures, but includes sample results. Standard TPIV analysis resolves the log layer of the mean velocity and the linear decrease in total shear stress with distance from the wall. Single-pixel ensemble correlations reveal the buffer layer and top of the viscous sublayer. Analysis of the MZI data consists of two steps, namely critical spatial filtering of interferograms to remove noise and phase demodulation to calculate the surface shape. A new technique to improve the filtration of noise from interferograms based on spatial correlations of small windows is introduced and optimized. Taking advantage of this enhancement, the phase/deformation distribution is calculated directly from arccosines of the intensity, which avoids edge artifacts affecting spectral calculations. Validations using synthetic noisy interferograms indicate that errors associated with correlation-based enhancement are consistently lower and much less sensitive to fringe shape than spectral band-pass filtering. The experimental wavenumber-frequency spectra show that the deformation consists of patterns that are larger than the field of view, surface waves and small-scale patterns. Some of the latter are advected at the freestream velocity, but mostly at 70 % of the freestream, the mean speed at 10 % of the channel half height. Indeed, spatial correlations of the deformation with velocity components peak at this elevation.

  7. Slow Ion Interferometry

    NASA Astrophysics Data System (ADS)

    Erickson, Christopher; Durfee, Dallin

    2009-05-01

    We will discuss an ion interferometer which is under construction. The device will utilize a laser-cooled source of ^87Sr^+ ions which will be split and recombined using stimulated Raman transitions inside of a conducting cylinder. The interferometer will be able to measure electric and magnetic fields with unprecedented precision. Potential uses of the device include practical applications such as the precision measurement of the evolution of fields near solids to reveal their electronic structure. It will also be used for fundamental tests of the basic laws of electromagnetism and the search for a non-zero photon rest mass. The device should enable the detection of a possible photon rest mass more than 100 times smaller than previous laboratory experiments. We will discuss both the details of the device and the theory connecting deviations from Coulomb's inverse-square law to a theory of massive photons.

  8. Deformations and strains in adhesive joints by moire interferometry

    NASA Technical Reports Server (NTRS)

    Post, D.; Czarnek, R.; Wood, J.; John, D.; Lubowinski, S.

    1984-01-01

    Displacement fields in a thick adherend lap joint and a cracked lap shear specimen were measured by high sensitivity moire interferometry. Contour maps of in-plane U and V displacements were obtained across adhesive and adherent surfaces. Loading sequences ranged from modest loads to near-failure loads. Quantitative results are given for displacements and certain strains in the adhesive and along the adhesive/adherend boundary lines. The results show nonlinear displacements and strains as a function of loads or stresses and they show viscoelastic or time-dependent response. Moire interferometry is an excellent method for experimental studies of adhesive joint performance. Subwavelength displacement resolution of a few micro-inches, and spatial resolution corresponding to 1600 fringes/inch (64 fringes/mm), were obtained in these studies. The whole-field contour maps offer insights not available from local measurements made by high sensitivity gages.

  9. Searching for Dark Matter with Atomic Clocks and Laser Interferometry

    NASA Astrophysics Data System (ADS)

    Stadnik, Yevgeny; Flambaum, Victor

    2016-05-01

    We propose new schemes for the direct detection of low-mass bosonic dark matter, which forms a coherently oscillating classical field and resides in the observed galactic dark matter haloes, using atomic clock, atomic spectroscopy and laser interferometry measurements in the laboratory. We have recently shown that such dark matter can produce both a `slow' cosmological evolution and oscillating variations in the fundamental constants. Using recent atomic dysprosium spectroscopy measurements in, we have derived limits on the quadratic interactions of scalar dark matter with ordinary matter that improve on existing constraints by up to 15 orders of magnitude. We have also proposed the use of laser and maser interferometry as novel high-precision platforms to search for dark matter, with effects due to the variation of the electromagnetic fine-structure constant on alterations in the accumulated phase enhanced by up to 14 orders of magnitude. Other possibilities include the use of highly-charged ions, molecules and nuclear clocks.

  10. Holodiagram: elliptic visualizing interferometry, relativity, and light-in-flight.

    PubMed

    Abramson, Nils H

    2014-04-10

    In holographic interferometry, there is usually a static distance separating the point of illumination and the point of observation. In Special Relativity, this separation is dynamic and is caused by the velocity of the observer. The corrections needed to compensate for these separations are similar in the two fields. We use the ellipsoids of the holodiagram for measurement and in a graphic way to explain and evaluate optical resolution, gated viewing, radar, holography, three-dimensional interferometry, Special Relativity, and light-in-flight recordings. Lorentz contraction together with time dilation is explained as the result of the eccentricity of the measuring ellipsoid, caused by its velocity. The extremely thin ellipsoid of the very first light appears as a beam aimed directly at the observer, which might explain the wave or ray duality of light and entanglement. Finally, we introduce the concept of ellipsoids of observation. PMID:24787410

  11. 50 years of holographic interferometry

    NASA Astrophysics Data System (ADS)

    Stetson, Karl A.

    2015-01-01

    Fifty years ago, Robert L. Powell and I discovered holographic interferometry while working at the Radar Laboratory of the University of Michigan's Institute of Science and Technology. I have worked in this field for this entire time span, watched it grow from an unexplored technology to become a widespread industrial testing method, and I have contributed to these developments. In this paper, I will trace my history in this field from our discovery to my involvement in its theory and applications. I will conclude with a discussion of digital holography, which is currently replacing photographic holography for most research and industrial applications.

  12. Golographic interferometry of physical processes

    NASA Astrophysics Data System (ADS)

    Ostrovskaya, G. V.

    2016-06-01

    This paper is devoted to the contribution of Yuri Ostrovsky to holographic interferometry, one of the fundamental scientific and practical applications of holography. The title of this paper is the same as the title of his doctoral thesis that he defended in 1974, and, as it seems to me, reflects most of the specific features of the majority of his scientific publications, viz., an inseparable link of the methods developed by him with the results obtained with the help of these methods in a wide range of investigations of physical processes and phenomena.

  13. Two-frequency Ramsey interferometry

    SciTech Connect

    Seidel, D.; Muga, J. G.

    2007-02-15

    We investigate Ramsey interferometry for two separated fields oscillating with different frequencies. It is shown that the interplay between average and relative detuning leads to interference effects not present in the standard, single-frequency setup. For a large free-flight time of ground-state atoms before entering the first field region, the Ramsey fringes with respect to the relative detuning become much narrower than the usual ones. The stability of these effects with respect to phase or velocity fluctuations is discussed.

  14. HBT interferometry and the parton-hadron phase transition

    SciTech Connect

    Soff, Sven

    2002-02-23

    The authors discuss predictions for the pion and kaon interferometry measurements in relativistic heavy ion collisions at SPS and RHIC energies. In particular, they confront relativistic transport model calculations that include explicitly a first-order phase transition from a thermalized quark-gluon plasma to a hadron gas with recent data from the RHIC experiments. They critically examine the HBT-puzzle both from the theoretical as well as from the experimental point of view. Alternative scenarios are briefly explained.

  15. Laser Development for Gravitational-Wave Interferometry in Space

    NASA Astrophysics Data System (ADS)

    Numata, K.

    2013-01-01

    We are reporting on our development work on laser (master oscillator) and optical amplifier systems for gravitational-wave interferometry in space. Our system is based on the mature, wave-guided optics technologies, which have advantages over bulk, crystal-based, free-space optics. We are investing in a new type of compact, low-noise master oscillator, called the planar-waveguide external cavity diode laser. We made measurements, including those of noise, and performed space-qualification tests.

  16. Laser Development for Gravitational-Wave Interferometry in Space

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Camp, Jordan

    2012-01-01

    We are reporting on our development work on laser (master oscillator) and optical amplifier systems for gravitational-wave interferometry in space. Our system is based on the mature, wave-guided optics technologies, which have advantages over bulk, crystal-based, free-space optics. We are investing in a new type of compact, low-noise master oscillator, called the planar-waveguide external cavity diode laser. We made measurements, including those of noise, and performed space-qualification tests.

  17. Real-time laser holographic Interferometry for aerodynamics

    NASA Technical Reports Server (NTRS)

    Lee, George

    1987-01-01

    Recent developments in thermoplastic recording holograms and advancements in automated image digitalization and analysis make real-time laser holographic interferometry feasible for two-dimensional flows such as airfoil flows. Typical airfoil measurements would include airfoil presssure distributions, wake and boundary layer profiles, and flow field density contours. This paper addresses some of the problems and requirements of a real-time laser holographic interferometer.

  18. Real-time laser holographic interferometry for aerodynamics

    NASA Technical Reports Server (NTRS)

    Lee, George

    1987-01-01

    Recent developments in thermoplastic recording holograms and advancements in automated image digitalization and analysis make real-time laser holographic interferometry feasible for two-dimensional flows such as airfoil flows. Typical airfoil measurements would include airfoil pressure distributions, wake and boundary layer profiles, and flow field density contours. This paper addresses some of the problems and requirements of a real-time laser holographic interferometer.

  19. Decorrelation analysis of L-band interferometry over the Piton de la Fournaise volcano (France) using airborne LiDAR data and in situ measurements

    NASA Astrophysics Data System (ADS)

    Sedze, M.; Bretar, F.; Heggy, E.; Berveiller, D.; Jacquemoud, S.

    2012-12-01

    We combine ALOS-PALSAR coherence images with airborne LiDAR data, both acquired over the Piton de la Fournaise volcano (Reunion Island, France) in 2008 and 2009, to determine the cause of errors that affects repeat-pass InSAR measurements. We investigate how phase coherence varies with the nature of volcanic terrains and vegetation density in a typical volcanic environment. Our study is focused on several sites characterized by different vegetation densities (Leaf Area Index or LAI) and on bare volcanic surfaces displaying different geophysical properties: pahoehoe and a'a lava flows, slabby pahoehoe flows, and pyroclastic deposits (lapillis). The high resolution DTM generated using LiDAR data is used to subtract out the topographic contribution from the interferogram and to improve the radar coherence maps. To evaluate the coherence loss terms, the relationship between LiDAR intensity and radar coherence is then analyzed over several surfaces. Pyroclastic deposits and a'a lava flows are characterized by low coherence and intensity values, with high coherence standard deviations; pahoehoe and slabby lava flows display high coherence and intensity values, with low standard deviations; coherence decreases in regions covered with dense vegetation, whereas LiDAR intensity increases, and we observe a higher dispersion of coherence and intensity values depending on the type and density of plants. Additionally, a geological survey has been conducted in October 2011 to measure the physical properties of the surface and better interpret the radar images. From digital photographs, we first computed ~ 25 m^2 DTM at 1 mm spatial resolution using an automatic image matching method. Several 4 m long linear profiles have been extracted to calculate three roughness parameters: the standard deviation of height σ, the correlation length L_c, and the Z_s parameter defined as Z_s= σ^2/L_c. They describe soil surface microrelief: the rougher the surface, the lower the correlation

  20. Synchrotron Light Interferometry at Jefferson Lab

    SciTech Connect

    Arne Freyberger; Pavel Chevtsov; Anthony Day; William Hicks

    2004-07-01

    The hyper-nuclear physics program at JLAB requires an upper limit on the RMS momentum spread of {delta}p/p < 3 x 10{sup -5}. The momentum spread is determined by measuring the beam width at a dispersive location (D {approx} 4m) in the transport line to the experimental halls. Ignoring the epsilon-beta contribution to the intrinsic beam size, this momentum spread corresponds to an upper bound on the beam width of {sigma}{sub beam} < 120 {micro}m. Typical techniques to measure and monitor the beam size are either invasive or do not have the resolution to measure such small beam sizes. Using interferometry of the synchrotron light produced in the dispersive bend, the resolution of the optical system can be made very small. The non-invasive nature of this measurement allows continuous monitoring of the momentum spread. Two synchrotron light interferometers have been built and installed at JLAB, one each in the Hall-A and Hall-C transport lines. The devices operate over a beam current range from 20 {micro}A to 120 {micro}A and have a spatial resolution of 10um. The structure of the interferometers, the experience gained during its installation, beam measurements and momentum spread stability are presented. The dependence of the measured momentum spread on beam current will be presented.