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.

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.

Crack displacement sensing and measurement in concrete using circular grating moire fringes and pattern matching

NASA Astrophysics Data System (ADS)

Chan, H. M.; Yen, K. S.; Ratnam, M. M.

2008-09-01

The moire method has been extensively studied in the past and applied in various engineering applications. Several techniques are available for generating the moire fringes in these applications, which include moire interferometry, projection moire, shadow moire, moire deflectometry etc. Most of these methods use the superposition of linear gratings to generate the moire patterns. The use of non-linear gratings, such as circular, radial and elongated gratings has received less attention from the research community. The potential of non-linear gratings in engineering measurement has been realized in a limited number of applications, such as rotation measurement, measurement of linear displacement, measurement of expansion coefficients of materials and measurement of strain distribution. In this work, circular gratings of different pitch were applied to the sensing and measurement of crack displacement in concrete structures. Gratings of pitch 0.50 mm and 0.55 mm were generated using computer software and attached to two overlapping acrylic plates that were bonded to either side of the crack. The resulting moire patterns were captured using a standard digital camera and compared with a set of reference patterns generated using a precision positioning stage. Using several image pre-processing stages, such as filtering and morphological operations, and pattern matching the magnitude displacements along two orthogonal axes can be detected with a resolution of 0.05 mm.

Electronic heterodyne moire deflectometry: A method for transient and three dimensional density fields measurements

NASA Technical Reports Server (NTRS)

Stricker, Josef

1987-01-01

Effects of diffraction and nonlinear photographic emulsion characteristics on the performance of deferred electronic heterodyne moire deflectometry are investigated. The deferred deflectometry is used for measurements of nonsteady phase objects where it is difficult to complete the analysis of the field in real time. The sensitivity, accuracy and resolution of the system are calculated and it is shown that they are weakly affected by diffraction and by nonlinear recording. The feactures of the system are significantly improved compared with the conventional deferred intensity moire technique, and are comparable with the online heterodyne moire. The system was evaluated experimentally by deferred measurements of the refractive index gradients of a weak phase object consisting of a large KD*P crystal. This was done by photographing the phase object through a Ronchi grating and analyzing the tranparency with the electronic heterodyne readout system. The results are compared with the measurements performed on the same phase object with online heterodyne moire deflectometry and with heterodyne holographic interferometry methods. Some practical considerations for system improvement are discussed.

Digital Moiré based transient interferometry and its application in optical surface measurement

NASA Astrophysics Data System (ADS)

Hao, Qun; Tan, Yifeng; Wang, Shaopu; Hu, Yao

2017-10-01

Digital Moiré based transient interferometry (DMTI) is an effective non-contact testing methods for optical surfaces. In DMTI system, only one frame of real interferogram is experimentally captured for the transient measurement of the surface under test (SUT). When combined with partial compensation interferometry (PCI), DMTI is especially appropriate for the measurement of aspheres with large apertures, large asphericity or different surface parameters. Residual wavefront is allowed in PCI, so the same partial compensator can be applied to the detection of multiple SUTs. Excessive residual wavefront aberration results in spectrum aliasing, and the dynamic range of DMTI is limited. In order to solve this problem, a method based on wavelet transform is proposed to extract phase from the fringe pattern with spectrum aliasing. Results of simulation demonstrate the validity of this method. The dynamic range of Digital Moiré technology is effectively expanded, which makes DMTI prospective in surface figure error measurement for intelligent fabrication of aspheric surfaces.

Higher-dimensional phase imaging

NASA Astrophysics Data System (ADS)

Huntley, Jonathan M.

2010-04-01

Traditional full-field interferometric techniques (speckle, moiré, holography etc) provide 2-D phase images, which encode the surface deformation state of the object under test. Over the past 15 years, the use of additional spatial or temporal dimensions has been investigated by a number of research groups. Early examples include the measurement of 3-D surface profiles by temporally-varying projected fringe patterns, and dynamic speckle interferometry. More recently (the past 5 years) a family of related techniques (Wavelength Scanning Interferometry, Phase Contrast Spectral Optical Coherence Tomography (OCT), and Tilt Scanning Interferometry) has emerged that provides the volume deformation state of the object. The techniques can be thought of as a marriage between the phase sensing capabilities of Phase Shifting Interferometry and the depth-sensing capabilities of OCT. Finally, in the past 12 months a technique called Hyperspectral Interferometry has been proposed in which absolute optical path distributions are obtained in a single shot through the spectral decomposition of a white light interferogram, and for which the additional dimension therefore corresponds to the illumination wavenumber. An overview of these developments, and the related issue of robust phase unwrapping of noisy 3-D wrapped phase volumes, is presented in this paper.

A study of model deflection measurement techniques applicable within the national transonic facility

NASA Technical Reports Server (NTRS)

Hildebrand, B. P.; Doty, J. L.

1982-01-01

Moire contouring, scanning interferometry, and holographic contouring were examined to determine their practicality and potential to meet performance requirements for a model deflection sensor. The system envisioned is to be nonintrusive, and is to be capable of mapping or contouring the surface of a 1-meter by 1-meter model with a resolution of 50 to 100 points. The available literature was surveyed, and computations and analyses were performed to establish specific performance requirements, as well as the capabilities and limitations of such a sensor within the geometry of the NTF section test section. Of the three systems examined, holographic contouring offers the most promise. Unlike Moire, it is not hampered by limited contour spacing and extraneous fringes. Its transverse resolution can far exceed the limited point sampling resolution of scanning heterodyne interferometry. The availability of the ruby laser as a high power, pulsed, multiple wavelength source makes such a system feasible within the NTF.

Experimental determination of release fields in cut railroad car wheels

DOT National Transportation Integrated Search

1999-02-01

A new approach to the measurement of residual stresses in railroad wheels is investigated using a saw cut method of releasing stresses in the structure. High-sensitivity moire interferometry combined with Michelson interferometry provides full-field ...

Advances in Projection Moire Interferometry Development for Large Wind Tunnel Applications

NASA Technical Reports Server (NTRS)

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

1999-01-01

An instrument development program aimed at using Projection Moire Interferometry (PMI) for acquiring model deformation measurements in large wind tunnels was begun at NASA Langley Research Center in 1996. Various improvements to the initial prototype PMI systems have been made throughout this development effort. This paper documents several of the most significant improvements to the optical hardware and image processing software, and addresses system implementation issues for large wind tunnel applications. The improvements have increased both measurement accuracy and instrument efficiency, promoting the routine use of PMI for model deformation measurements in production wind tunnel tests.

Comparison of Three Optical Methods for Measuring Model Deformation

NASA Technical Reports Server (NTRS)

Burner, A. W.; Fleming, G. A.; Hoppe, J. C.

2000-01-01

The objective of this paper is to compare the current state-of-the-art of the following three optical techniques under study by NASA for measuring model deformation in wind tunnels: (1) video photogrammetry, (2) projection moire interferometry, and (3) the commercially available Optotrak system. An objective comparison of these three techniques should enable the selection of the best technique for a particular test undertaken at various NASA facilities. As might be expected, no one technique is best for all applications. The techniques are also not necessarily mutually exclusive and in some cases can be complementary to one another.

Holographic Moire, An Optical Tool For The Determination Of Displacements, Strains, Contours, And Slopes Of Surfaces

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.

1982-06-01

In conventional holographic interferometry, the observed fringe patterns are determined by the object displacement and deformation, and by the illumination and observation configurations. The obtained information may not be in the most convenient form for further data processing. To overcome this problem, and to create new possibilities, holographic fringe patterns can be changed by modifying the optical setup. As a result of these modifications, well-known procedures of the moire method can be applied to holographic interferometry. Components of displacement and components of the strain tensor can be isolated and measured separately. Surface contours and slopes can also be determined.

Precision improving of double beam shadow moiré interferometer by phase shifting interferometry for the stress of flexible substrate

NASA Astrophysics Data System (ADS)

Huang, Kuo-Ting; Chen, Hsi-Chao; Lin, Ssu-Fan; Lin, Ke-Ming; Syue, Hong-Ye

2012-09-01

While tin-doped indium oxide (ITO) has been extensively applied in flexible electronics, the problem of the residual stress has many obstacles to overcome. This study investigated the residual stress of flexible electronics by the double beam shadow moiré interferometer, and focused on the precision improvement with phase shifting interferometry (PSI). According to the out-of-plane displacement equation, the theoretical error depends on the grating pitch and the angle between incident light and CCD. The angle error could be reduced to 0.03% by the angle shift of 10° as a result of the double beam interferometer was a symmetrical system. But the experimental error of the double beam moiré interferometer still reached to 2.2% by the noise of the vibration and interferograms. In order to improve the measurement precision, PSI was introduced to the double shadow moiré interferometer. Wavefront phase was reconstructed by the five interferograms with the Hariharan algorithm. The measurement results of standard cylinder indicating the error could be reduced from 2.2% to less than 1% with PSI. The deformation of flexible electronic could be reconstructed fast and calculated the residual stress with the Stoney correction formula. This shadow moiré interferometer with PSI could improve the precision of residual stress for flexible electronics.

A curved surface micro-moiré method and its application in evaluating curved surface residual stress

NASA Astrophysics Data System (ADS)

Zhang, Hongye; Wu, Chenlong; Liu, Zhanwei; Xie, Huimin

2014-09-01

The moiré method is typically applied to the measurement of deformations of a flat surface while, for a curved surface, this method is rarely used other than for projection moiré or moiré interferometry. Here, a novel colour charge-coupled device (CCD) micro-moiré method has been developed, based on which a curved surface micro-moiré (CSMM) method is proposed with a colour CCD and optical microscope (OM). In the CSMM method, no additional reference grating is needed as a Bayer colour filter array (CFA) installed on the OM in front of the colour CCD image sensor performs this role. Micro-moiré fringes with high contrast are directly observed with the OM through the Bayer CFA under the special condition of observing a curved specimen grating. The principle of the CSMM method based on a colour CCD micro-moiré method and its application range and error analysis are all described in detail. In an experiment, the curved surface residual stress near a welded seam on a stainless steel tube was investigated using the CSMM method.

Optics for Processes, Products and Metrology

NASA Astrophysics Data System (ADS)

Mather, George

1999-04-01

Optical physics has a variety of applications in industry, including process inspection, coatings development, vision instrumentation, spectroscopy, and many others. Optics has been used extensively in the design of solar energy collection systems and coatings, for example. Also, with the availability of good CCD cameras and fast computers, it has become possible to develop real-time inspection and metrology devices that can accommodate the high throughputs encountered in modern production processes. More recently, developments in moiré interferometry show great promise for applications in the basic metals and electronics industries. The talk will illustrate applications of optics by discussing process inspection techniques for defect detection, part dimensioning, birefringence measurement, and the analysis of optical coatings in the automotive, glass, and optical disc industries. In particular, examples of optical techniques for the quality control of CD-R, MO, and CD-RW discs will be presented. In addition, the application of optical concepts to solar energy collector design and to metrology by moiré techniques will be discussed. Finally, some of the modern techniques and instruments used for qualitative and quantitative material analysis will be presented.

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.

Electro optical system to measure strains

NASA Astrophysics Data System (ADS)

Sciammarella, C. A.; Bhat, G.

With the advent of the so called speckle interferometry, interferograms of objects can be obtained in real time by using a TV camera as the recording medium. The basic idea of this instrument is to couple the photoelectric registration by a TV camera with the subsequent electronic processing, to develop an efficient device for the measurement of deformations. This paper presents a new and improved instrument, which has a very important feature, portability, that can be operated in different modes and is capable of producing interferograms using holography, speckle, and moire methods. The basic features of the instrument are presented and some of the theoretical points at the foundation of operation of the instrument are analyzed. Examples are given of the application to moire, speckle, and holographic interferometry.

Measurement of strains at high temperatures by means of electro-optics holography

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Bhat, G.; Vaitekunas, Jeffrey

Electro-optics holographic-moire interferometry is used to measure strains at temperatures up to 1000 C. A description of the instrumentation developed to carry out the measurements is given. The data processing technique is also explained. Main problems encountered in recording patterns at high temperatures are analyzed and possible solutions are outlined. Optical results are compared with strain gage values obtained with instrumented specimens and with theoretical results. Very good agreement is found between optical, strain gage and theoretical results.

Measurement of strains at high temperatures by means of electro-optics holography

NASA Technical Reports Server (NTRS)

Sciammarella, Cesar A.; Bhat, G.; Vaitekunas, Jeffrey

1991-01-01

Electro-optics holographic-moire interferometry is used to measure strains at temperatures up to 1000 C. A description of the instrumentation developed to carry out the measurements is given. The data processing technique is also explained. Main problems encountered in recording patterns at high temperatures are analyzed and possible solutions are outlined. Optical results are compared with strain gage values obtained with instrumented specimens and with theoretical results. Very good agreement is found between optical, strain gage and theoretical results.

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.

Study of optical techniques for the Ames unitary wind tunnels. Part 4: Model deformation

NASA Technical Reports Server (NTRS)

Lee, George

1992-01-01

A survey of systems capable of model deformation measurements was conducted. The survey included stereo-cameras, scanners, and digitizers. Moire, holographic, and heterodyne interferometry techniques were also looked at. Stereo-cameras with passive or active targets are currently being deployed for model deformation measurements at NASA Ames and LaRC, Boeing, and ONERA. Scanners and digitizers are widely used in robotics, motion analysis, medicine, etc., and some of the scanner and digitizers can meet the model deformation requirements. Commercial stereo-cameras, scanners, and digitizers are being improved in accuracy, reliability, and ease of operation. A number of new systems are coming onto the market.

Deformation analysis of boron/aluminum specimens by moire interferometry

NASA Technical Reports Server (NTRS)

Post, Daniel; Guo, Yifan; Czarnek, Robert

1989-01-01

Whole-field surface deformations were measured for two slotted tension specimens from multiply laminates, one with 0 deg fiber orientation in the surface ply and the other with 45 deg orientation. Macromechanical and micromechanical details were revealed using high-sensitivity moire interferometry. Although global deformations of all plies were essentially equal, numerous random or anomalous features were observed. Local deformations of adjacent 0 deg and 45 deg plies were very different, both near the slot and remote from it, requiring large interlaminar shear strains for continuity. Shear strains were concentrated in the aluminum matrix. For 45 deg plies, a major portion of the deformation was by shear; large plastic slip of matrix occurred at random locations in 45 deg plies, wherein groups of fibers slipped relative to other groups. Shear strains in the interior, between adjacent fibers, were larger than the measured surface strains.

Measuring Joule heating and strain induced by electrical current with Moire interferometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen Bicheng; Basaran, Cemal

2011-04-01

This study proposes a new method to locate and measure the temperature of the hot spots caused by Joule Heating by measuring the free thermal expansion in-plane strain. It is demonstrated that the hotspot caused by the Joule heating in a thin metal film/plate structure can be measured by Phase shifting Moire interferometry with continuous wavelet transform (PSMI/CWT) at the microscopic scale. A demonstration on a copper film is conducted to verify the theory under different current densities. A correlation between the current density and strain in two orthogonal directions (one in the direction of the current flow) is proposed.more » The method can also be used for the measurement of the Joule heating in the microscopic solid structures in the electronic packaging devices. It is shown that a linear relationship exists between current density squared and normal strains.« less

Precision topographic inspection of MOEMS by moiré interferometry

NASA Astrophysics Data System (ADS)

Meguellati, S.

2016-04-01

The manufacturing of micro components is useful and necessary for eventual use in the field of MOEMS micro technologies, but, micro fabrication process inspection quality is required. The accuracy of components geometry is parameter which influences the precision of the function. Moiré topography is full-field optical technique in which the contour and shape of object surfaces is measured by means of geometric interference between two identical line gratings. The technique has found various applications in diverse fields, from biomedical to industrial, scientific applications, and miniaturized instrumentation for space applications. This method of optical scanning presented in this paper is used for precision measurement deformation or absolute forms in comparison with a reference component form, of optical or mechanical micro components, on surfaces that are of the order of mm2 and more. The optical device used allows high magnification dimensional surface inspected which allows easy processing and reaches an exceptional nanometric imprecision of measurements. This measurement technique can be used advantageously to measure the deformations generated by constraints on functional parts and the influence of these variations on the function. It can also be used for dimensional control when, for example, to quantify the error as to whether a piece is good or rubbish. It then suffices to compare a figure of moiré fringes with another previously recorded from a piece considered standard, which saves time, money and accuracy. This method of control and measurement allows real time control; speed control and the detection resolution may vary depending on the importance of defects to be measured.

A Micromachined Geometric Moire Interferometric Floating-Element Shear Stress Sensor

NASA Technical Reports Server (NTRS)

Horowitz, S.; Chen, T.; Chandrasekaran, V.; Tedjojuwono, K.; Nishida, T.; Cattafesta, L.; Sheplak, M.

2004-01-01

This paper presents the development of a floating-element shear stress sensor that permits the direct measurement of skin friction based on geometric Moir interferometry. The sensor was fabricated using an aligned wafer-bond/thin-back process producing optical gratings on the backside of a floating element and on the top surface of the support wafer. Experimental characterization indicates a static sensitivity of 0.26 microns/Pa, a resonant frequency of 1.7 kHz, and a noise floor of 6.2 mPa/(square root)Hz.

HSR Model Deformation Measurements from Subsonic to Supersonic Speeds

NASA Technical Reports Server (NTRS)

Burner, A. W.; Erickson, G. E.; Goodman, W. L.; Fleming, G. A.

1999-01-01

This paper describes the video model deformation technique (VMD) used at five NASA facilities and the projection moire interferometry (PMI) technique used at two NASA facilities. Comparisons between the two techniques for model deformation measurements are provided. Facilities at NASA-Ames and NASA-Langley where deformation measurements have been made are presented. Examples of HSR model deformation measurements from the Langley Unitary Wind Tunnel, Langley 16-foot Transonic Wind Tunnel, and the Ames 12-foot Pressure Tunnel are presented. A study to improve and develop new targeting schemes at the National Transonic Facility is also described. The consideration of milled targets for future HSR models is recommended when deformation measurements are expected to be required. Finally, future development work for VMD and PMI is addressed.

High speed photography, videography, and photonics III; Proceedings of the Meeting, San Diego, CA, August 22, 23, 1985

NASA Technical Reports Server (NTRS)

Ponseggi, B. G. (Editor); Johnson, H. C. (Editor)

1985-01-01

Papers are presented on the picosecond electronic framing camera, photogrammetric techniques using high-speed cineradiography, picosecond semiconductor lasers for characterizing high-speed image shutters, the measurement of dynamic strain by high-speed moire photography, the fast framing camera with independent frame adjustments, design considerations for a data recording system, and nanosecond optical shutters. Consideration is given to boundary-layer transition detectors, holographic imaging, laser holographic interferometry in wind tunnels, heterodyne holographic interferometry, a multispectral video imaging and analysis system, a gated intensified camera, a charge-injection-device profile camera, a gated silicon-intensified-target streak tube and nanosecond-gated photoemissive shutter tubes. Topics discussed include high time-space resolved photography of lasers, time-resolved X-ray spectrographic instrumentation for laser studies, a time-resolving X-ray spectrometer, a femtosecond streak camera, streak tubes and cameras, and a short pulse X-ray diagnostic development facility.

Four-quadrant gratings moiré fringe alignment measurement in proximity lithography.

PubMed

Zhu, Jiangping; Hu, Song; Yu, Junsheng; Zhou, Shaolin; Tang, Yan; Zhong, Min; Zhao, Lixin; Chen, Minyong; Li, Lanlan; He, Yu; Jiang, Wei

2013-02-11

This paper aims to deal with a four-quadrant gratings alignment method benefiting from phase demodulation for proximity lithography, which combines the advantages of interferometry with image processing. Both the mask alignment mark and the wafer alignment mark consist of four sets of gratings, which bring the convenience and simplification of realization for coarse alignment and fine alignment. Four sets of moiré fringes created by superposing the mask alignment mark and the wafer alignment mark are highly sensitive to the misalignment between them. And the misalignment can be easily determined through demodulating the phase of moiré fringe without any external reference. Especially, the period and phase distribution of moiré fringes are unaffected by the gap between the mask and the wafer, not excepting the wavelength of alignment illumination. Disturbance from the illumination can also be negligible, which enhances the technological adaptability. The experimental results bear out the feasibility and rationality of our designed approach.

Residual Microstrain in Root Dentin after Canal Instrumentation Measured with Digital Moiré Interferometry.

PubMed

Lim, Helena; Li, Fang-Chi; Friedman, Shimon; Kishen, Anil

2016-09-01

Residual microstrain influences the resistance to crack propagation in a biomaterial. This study evaluated the residual microstrain and microdefects formed in dentin after canal instrumentation in teeth maintained in hydrated and nonhydrated environments. Canals of 18 extracted human premolars with single-root canals were instrumented in accordance with 3 groups: the ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) group: ProTaper Universal (S1, S2, F1, and F2) used in rotation, the WaveOne Primary (Dentsply Maillefer) group: the WaveOne (Primary) used in reciprocal motion, and the control group: hand files. Half the specimens (3/group) were maintained in deionized water (hydrated) and half in ambient relative humidity conditions (22°C, 55% RH) for 72 hours (nonhydrated). Customized high-sensitivity digital moiré interferometry was used to qualitatively evaluate pre- and postinstrumentation dentinal microstrain. Subsequently, specimens were examined for dentinal microdefects with micro-computed tomographic imaging and polarized light microscopy. Digital moiré interferometry showed only minor changes in postinstrumentation microstrain in hydrated dentin in all groups, suggestive of a stress relaxation behavior. Nonhydrated dentin in all groups showed localized concentration of postinstrumentation microstrain, which appeared higher in the WaveOne group than in the other groups. No dentinal microdefects were detected by micro-computed tomographic imaging and polarized light microscopy in hydrated and nonhydrated specimens in all groups. This study suggested that the biomechanical response of root dentin to instrumentation was influenced by hydration. Reciprocating, rotary, and hand instrumentation of well-hydrated roots did not cause an increase in residual microstrain or the formation of microdefects in root dentin. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Talbot-Lau x-ray deflectometry phase-retrieval methods for electron density diagnostics in high-energy density experiments.

PubMed

Valdivia, Maria Pia; Stutman, Dan; Stoeckl, Christian; Mileham, Chad; Begishev, Ildar A; Bromage, Jake; Regan, Sean P

2018-01-10

Talbot-Lau x-ray interferometry uses incoherent x-ray sources to measure refraction index changes in matter. These measurements can provide accurate electron density mapping through phase retrieval. An adaptation of the interferometer has been developed in order to meet the specific requirements of high-energy density experiments. This adaptation is known as a moiré deflectometer, which allows for single-shot capabilities in the form of interferometric fringe patterns. The moiré x-ray deflectometry technique requires a set of object and reference images in order to provide electron density maps, which can be costly in the high-energy density environment. In particular, synthetic reference phase images obtained ex situ through a phase-scan procedure, can provide a feasible solution. To test this procedure, an object phase map was retrieved from a single-shot moiré image obtained from a plasma-produced x-ray source. A reference phase map was then obtained from phase-stepping measurements using a continuous x-ray tube source in a small laboratory setting. The two phase maps were used to retrieve an electron density map. A comparison of the moiré and phase-stepping phase-retrieval methods was performed to evaluate single-exposure plasma electron density mapping for high-energy density and other transient plasma experiments. It was found that a combination of phase-retrieval methods can deliver accurate refraction angle mapping. Once x-ray backlighter quality is optimized, the ex situ method is expected to deliver electron density mapping with improved resolution. The steps necessary for improved diagnostic performance are discussed.

Metal matrix composites: Testing, analysis, and failure modes; Proceedings of the Symposium, Sparks, NV, Apr. 25, 26, 1988

NASA Technical Reports Server (NTRS)

Johnson, W. S. (Editor)

1989-01-01

The present conference discusses the tension and compression testing of MMCs, the measurement of advanced composites' thermal expansion, plasticity theory for fiber-reinforced composites, a deformation analysis of boron/aluminum specimens by moire interferometry, strength prediction methods for MMCs, and the analysis of notched MMCs under tensile loading. Also discussed are techniques for the mechanical and thermal testing of Ti3Al/SCS-6 MMCs, damage initiation and growth in fiber-reinforced MMCs, the shear testing of MMCs, the crack growth and fracture of continuous fiber-reinforced MMCs in view of analytical and experimental results, and MMC fiber-matrix interface failures.

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.

Measuring the residual stress of transparent conductive oxide films on PET by the double-beam shadow Moiré interferometer

NASA Astrophysics Data System (ADS)

Chen, Hsi-Chao; Huang, Kuo-Ting; Lo, Yen-Ming; Chiu, Hsuan-Yi; Chen, Guan-Jhen

2011-09-01

The purpose of this research was to construct a measurement system which can fast and accurately analyze the residual stress of the flexible electronics. The transparent conductive oxide (TCO) films, tin-doped indium oxide (ITO), were deposited by radio frequency (RF) magnetron sputtering using corresponding oxide targets on PET substrate. As we know that the shadow Moiré interferometry is a useable way to measure the large deformation. So we set up a double beam shadow Moiré interferometer to measure and analyze the residual stress of TCO films on PET. The feature was to develop a mathematical model and combine the image processing software. By the LabVIEW graphical software, we could measure the distance which is between the left and right fringe on the pattern to solve the curvature of deformed surface. Hence, the residual stress could calculate by the Stoney correction formula for the flexible electronics. By combining phase shifting method with shadow Moiré, the measurement resolution and accuracy have been greatly improved. We also had done the error analysis for the system whose relative error could be about 2%. Therefore, shadow Moiré interferometer is a non-destructive, fast, and simple system for the residual stress on TCO/PET films.

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.

Micro/Nano-scale Strain Distribution Measurement from Sampling Moiré Fringes.

PubMed

Wang, Qinghua; Ri, Shien; Tsuda, Hiroshi

2017-05-23

This work describes the measurement procedure and principles of a sampling moiré technique for full-field micro/nano-scale deformation measurements. The developed technique can be performed in two ways: using the reconstructed multiplication moiré method or the spatial phase-shifting sampling moiré method. When the specimen grid pitch is around 2 pixels, 2-pixel sampling moiré fringes are generated to reconstruct a multiplication moiré pattern for a deformation measurement. Both the displacement and strain sensitivities are twice as high as in the traditional scanning moiré method in the same wide field of view. When the specimen grid pitch is around or greater than 3 pixels, multi-pixel sampling moiré fringes are generated, and a spatial phase-shifting technique is combined for a full-field deformation measurement. The strain measurement accuracy is significantly improved, and automatic batch measurement is easily achievable. Both methods can measure the two-dimensional (2D) strain distributions from a single-shot grid image without rotating the specimen or scanning lines, as in traditional moiré techniques. As examples, the 2D displacement and strain distributions, including the shear strains of two carbon fiber-reinforced plastic specimens, were measured in three-point bending tests. The proposed technique is expected to play an important role in the non-destructive quantitative evaluations of mechanical properties, crack occurrences, and residual stresses of a variety of materials.

Stress studies in EFG

NASA Technical Reports Server (NTRS)

1984-01-01

Electrical characterization of defects induced in FZ and CZ silicon stress in four-point bending above 1200 C was started. Techniques to study electrical activity that will permit correlation of defect activity with diffusion length and with room and low temperature EBIC are being developed. Preliminary characterization of defects in ribbon grown at very low speeds of less than 1 cm/min shows that the dislocation density is very low over significant regions of cross section, while regions of high dislocation density (approx. 5 x 10(6)/cm(2)) occur in bands in a number of places. Addition measurements of stress distributions in EFG material were obtained at the University of Illinois using shadow-Moire interferometry.

Improved grid-noise removal in single-frame digital moiré 3D shape measurement

NASA Astrophysics Data System (ADS)

Mohammadi, Fatemeh; Kofman, Jonathan

2016-11-01

A single-frame grid-noise removal technique was developed for application in single-frame digital-moiré 3D shape measurement. The ability of the stationary wavelet transform (SWT) to prevent oscillation artifacts near discontinuities, and the ability of the Fourier transform (FFT) applied to wavelet coefficients to separate grid-noise from useful image information, were combined in a new technique, SWT-FFT, to remove grid-noise from moiré-pattern images generated by digital moiré. In comparison to previous grid-noise removal techniques in moiré, SWT-FFT avoids the requirement for mechanical translation of optical components and capture of multiple frames, to enable single-frame moiré-based measurement. Experiments using FFT, Discrete Wavelet Transform (DWT), DWT-FFT, and SWT-FFT were performed on moiré-pattern images containing grid noise, generated by digital moiré, for several test objects. SWT-FFT had the best performance in removing high-frequency grid-noise, both straight and curved lines, minimizing artifacts, and preserving the moiré pattern without blurring and degradation. SWT-FFT also had the lowest noise amplitude in the reconstructed height and lowest roughness index for all test objects, indicating best grid-noise removal in comparison to the other techniques.

A study of the stress wave factor technique for the characterization of composite materials

NASA Technical Reports Server (NTRS)

Henneke, E. G., II; Duke, J. C., Jr.; Stinchcomb, W. W.; Govada, A.; Lemascon, A.

1983-01-01

A testing program was undertaken to provide an independent investigation and evaluation of the stress wave factor for characterizing the mechanical behavior of composite laminates. Some of the data which was obtained after performing a very large number of tests to determine the reproducibility of the SWF measurement is presented. It was determined that, with some optimizing of experimental parameters, the SWF value can be reproduced to within + or - 10%. Results are also given which show that, after careful calibration procedures, the lowest SWF value along the length of a specimen will correlate very closely to the site of final failure when the specimen is loaded in tension. Finally, using a moire interferometry technique, it was found that local regions having the highest in plane strains under tensile loading also had the lowest SWF values.

A study of the stress wave factor technique for the characterization of composite materials

NASA Technical Reports Server (NTRS)

Govada, A. K.; Duke, J. C., Jr.; Henneke, E. G., II; Stinchcomb, W. W.

1985-01-01

This study has investigated the potential of the Stress Wave Factor as an NDT technique for thin composite laminates. The conventional SWF and an alternate method for quantifying the SWF were investigated. Agreement between the initial SWF number, ultrasonic C-scan, inplane displacements as obtained by full field moire interferometry, and the failure location have been observed. The SWF number was observed to be the highest when measured along the fiber direction and the lowest when measured across the fibers. The alternate method for quantifying the SWF used square root of the zeroth moment (square root of M sub o) of the frequency spectrum of the received signal as a quantitative parameter. From this study it therefore appears that the stress wave factor has an excellent potential to monitor damage development in thin composite laminates.

A temporal phase unwrapping algorithm for photoelastic stress analysis

NASA Astrophysics Data System (ADS)

Baldi, Antonio; Bertolino, Filippo; Ginesu, Francesco

2007-05-01

Photoelastic stress analysis is a full-field optical technique for experimental stress analysis whose automation has received considerable research attention over the last 15 years. The latest developments have been made possible largely due to the availability of powerful calculators with large memory capacity and colour, high resolution, cameras. A further stimulus is provided by the photoelastic resins now used for rapid prototyping. However, one critical aspect which still deserves attention is phase unwrapping. The algorithms most commonly used for this purpose have been developed in other scientific areas (classical interferometry, profilometry, moiré, etc.) for solving different problems. In this article a new algorithm is proposed for temporal phase unwrapping, which offers several advantages over those used today.

Micro/nano moire methods

NASA Astrophysics Data System (ADS)

Asundi, Anand K.; Shang, Haixia; Xie, Huimin; Li, Biao

2003-10-01

Two novel micro/nano moire method, SEM scanning moiré and AFM scanning moire techniques are discussed in this paper. The principle and applications of two scanning moire methods are described in detail. The residual deformation in a polysilicon MEMS cantilever structure with a 5000 lines/mm grating after removing the SiO2 sacrificial layer is accurately measured by SEM scanning moire method. While AFM scanning moire method is used to detect thermal deformation of electronic package components, and formation of nano-moire on a freshly cleaved mica crystal. Experimental results demonstrate the feasibility of these two moire methods, and also show they are effective methods to measure the deformation from micron to nano-scales.

Local Displacements and Load Transfer of Shape Memory Alloys in Polymeric Matrices

DTIC Science & Technology

1997-01-01

plane displacements of room temperature cured SMA ribbon composites were obtained using moiré interferometry. Displacements due to thermal expansion ...141 Figure 6.10 Displacement profiles along SMA ribbon or different values of the coefficient of thermal expansion ...greater importance in polymer composites, which can have large coefficients of thermal expansion . Further, there is also a lack of experimental data

High-resolution computer-aided moire

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Bhat, Gopalakrishna K.

1991-12-01

This paper presents a high resolution computer assisted moire technique for the measurement of displacements and strains at the microscopic level. The detection of micro-displacements using a moire grid and the problem associated with the recovery of displacement field from the sampled values of the grid intensity are discussed. A two dimensional Fourier transform method for the extraction of displacements from the image of the moire grid is outlined. An example of application of the technique to the measurement of strains and stresses in the vicinity of the crack tip in a compact tension specimen is given.

A Comparison of Three Methods for Measuring Distortion in Optical Windows

NASA Technical Reports Server (NTRS)

Youngquist, Robert C.; Nurge, Mark A.; Skow, Miles

2015-01-01

It's 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.

Measurement of residual stresses by the moire method

NASA Astrophysics Data System (ADS)

Sciammarella, C. A.; Albertazzi, A., Jr.

Three different applications of the moire method to the determination of residual stresses and strains are presented. The three applications take advantage of the property of ratings to record the changes of the surface they are printed on. One of the applications deals with thermal residual stresses, another with contact residual stress and the third one is a generalization of the blind hole technique. This last application is based on a computer assisted moire technique and on the generalization of the quasi-heterodyne techniques of fringe pattern analysis.

A Moire Fringing Spectrometer for Extra-Solar Planet Searches

NASA Astrophysics Data System (ADS)

van Eyken, J. C.; Ge, J.; Mahadevan, S.; De Witt, C.; Ramsey, L. W.; Berger, D.; Shaklan, S.; Pan, X.

2001-12-01

We have developed a prototype moire fringing spectrometer for high precision radial velocity measurements for the detection of extra-solar planets. This combination of Michelson interferometer and spectrograph overlays an interferometer comb on a medium resolution stellar spectrum, producing Moire patterns. Small changes in the doppler shift of the spectrum lead to corresponding large shifts in the Moire pattern (Moire magnification). The sinusoidal shape of the Moire fringes enables much simpler measurement of these shifts than in standard echelle spectrograph techniques, facilitating high precision measurements with a low cost instrument. Current data analysis software we have developed has produced short-term repeatability (over a few hours) to 5-10m/s, and future planned improvements based on previous experiments should reduce this significantly. We plan eventually to carry out large scale surveys for low mass companions around other stars. This poster will present new results obtained in the lab and at the HET and Palomar 5m telescopes, the theory of the instrument, and data analysis techniques.

Advanced optical measuring systems for measuring the properties of fluids and structures

NASA Technical Reports Server (NTRS)

Decker, A. J.

1986-01-01

Four advanced optical models are reviewed for the measurement of visualization of flow and structural properties. Double-exposure, diffuse-illumination, holographic interferometry can be used for three-dimensional flow visualization. When this method is combined with optical heterodyning, precise measurements of structural displacements or fluid density are possible. Time-average holography is well known as a method for displaying vibrational mode shapes, but it also can be used for flow visualization and flow measurements. Deflectometry is used to measure or visualize the deflection of light rays from collimation. Said deflection occurs because of refraction in a fluid or because of reflection from a tilted surface. The moire technique for deflectometry, when combined with optical heterodyning, permits very precise measurements of these quantities. The rainbow schlieren method of deflectometry allows varying deflection angles to be encoded with colors for visualization.

A Computer Based Moire Technique To Measure Very Small Displacements

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Amadshahi, Mansour A.; Subbaraman, B.

1987-02-01

The accuracy that can be achieved in the measurement of very small displacements in techniques such as moire, holography and speckle is limited by the noise inherent to the utilized optical devices. To reduce the noise to signal ratio, the moire method can be utilized. Two system of carrier fringes are introduced, an initial system before the load is applied and a final system when the load is applied. The moire pattern of these two systems contains the sought displacement information and the noise common to the two patterns is eliminated. The whole process is performed by a computer on digitized versions of the patterns. Examples of application are given.

Moire technique utilization for detection and measurement of scoliosis

NASA Astrophysics Data System (ADS)

Zawieska, Dorota; Podlasiak, Piotr

1993-02-01

Moire projection method enables non-contact measurement of the shape or deformation of different surfaces and constructions by fringe pattern analysis. The fringe map acquisition of the whole surface of the object under test is one of the main advantages compared with 'point by point' methods. The computer analyzes the shape of the whole surface and next user can selected different points or cross section of the object map. In this paper a few typical examples of an application of the moire technique in solving different medical problems will be presented. We will also present to you the equipment the moire pattern analysis is done in real time using the phase stepping method with CCD camera.

Ridge augmentation with soft tissue procedures in aesthetic dentistry: first clinical results measured with a new kind of moire technique

NASA Astrophysics Data System (ADS)

Studer, Stephan P.; Bucher, Andreas; Mueller, Felix

1993-09-01

The oral health of the Swiss population was significantly improved by the successful prevention of dental caries and periodontitis. Along with the healthy dentition the demand for aesthetic dentistry is increasing. Removable partial dentures are becoming less accepted. Therefore, to substitute lost teeth by permanent fixed partial prosthesis (bridges), the often deformed alveolar ridge has to be operated, either to improve the aesthetic appearance or to make it possible to restore the missing teeth by a fixed cemented bridge. The aim of this paper is (1) to evaluate whether the moire technique is an appropriate and handy method, and (2) to validate the precision of the new method. The measuring system consisted of a moire projector with an integrated phase shift device and a moire viewer with a CCD video camera, connected to a frame grabber in a personal computer. a highly versatile software was allowed to control the system as well as to grab the moire images using the four-phase shift technique in order to compute the phase image of the actual object. The new technique was validated with one solid test object measured by a 3D coordination, high precision measuring machine.

Detection, location, and quantification of structural damage by neural-net-processed moiré profilometry

NASA Astrophysics Data System (ADS)

Grossman, Barry G.; Gonzalez, Frank S.; Blatt, Joel H.; Hooker, Jeffery A.

1992-03-01

The development of efficient high speed techniques to recognize, locate, and quantify damage is vitally important for successful automated inspection systems such as ones used for the inspection of undersea pipelines. Two critical problems must be solved to achieve these goals: the reduction of nonuseful information present in the video image and automatic recognition and quantification of extent and location of damage. Artificial neural network processed moire profilometry appears to be a promising technique to accomplish this. Real time video moire techniques have been developed which clearly distinguish damaged and undamaged areas on structures, thus reducing the amount of extraneous information input into an inspection system. Artificial neural networks have demonstrated advantages for image processing, since they can learn the desired response to a given input and are inherently fast when implemented in hardware due to their parallel computing architecture. Video moire images of pipes with dents of different depths were used to train a neural network, with the desired output being the location and severity of the damage. The system was then successfully tested with a second series of moire images. The techniques employed and the results obtained are discussed.

Development of Moire machine vision

NASA Technical Reports Server (NTRS)

Harding, Kevin G.

1987-01-01

Three dimensional perception is essential to the development of versatile robotics systems in order to handle complex manufacturing tasks in future factories and in providing high accuracy measurements needed in flexible manufacturing and quality control. A program is described which will develop the potential of Moire techniques to provide this capability in vision systems and automated measurements, and demonstrate artificial intelligence (AI) techniques to take advantage of the strengths of Moire sensing. Moire techniques provide a means of optically manipulating the complex visual data in a three dimensional scene into a form which can be easily and quickly analyzed by computers. This type of optical data manipulation provides high productivity through integrated automation, producing a high quality product while reducing computer and mechanical manipulation requirements and thereby the cost and time of production. This nondestructive evaluation is developed to be able to make full field range measurement and three dimensional scene analysis.

Development of Moire machine vision

NASA Astrophysics Data System (ADS)

Harding, Kevin G.

1987-10-01

Three dimensional perception is essential to the development of versatile robotics systems in order to handle complex manufacturing tasks in future factories and in providing high accuracy measurements needed in flexible manufacturing and quality control. A program is described which will develop the potential of Moire techniques to provide this capability in vision systems and automated measurements, and demonstrate artificial intelligence (AI) techniques to take advantage of the strengths of Moire sensing. Moire techniques provide a means of optically manipulating the complex visual data in a three dimensional scene into a form which can be easily and quickly analyzed by computers. This type of optical data manipulation provides high productivity through integrated automation, producing a high quality product while reducing computer and mechanical manipulation requirements and thereby the cost and time of production. This nondestructive evaluation is developed to be able to make full field range measurement and three dimensional scene analysis.

J-Resistance Curves of Aluminum Specimens Using Moire Interferometry

DTIC Science & Technology

1989-04-01

elastic-plastic fracture mechanics ( EPFM ) methodologies are based on the J-integral or the crack opening displacement (COD) approach. The J-resistance curve...in the HRR field [13,141. In this paper, we present further application of the approximate J-evaluation procedure in large 2024-0 and 5052-H32 aluminum...Davis, J. A. Joyce, and R. A. Hays, " Application of the J-Integral and the Modified J-Integral to Cases of Large Crack Extension and High Toughness

Deformation Measurements of Smart Aerodynamic Surfaces

NASA Technical Reports Server (NTRS)

Fleming, Gary A.; Burner, Alpheus

2005-01-01

Video Model Deformation (VMD) and Projection Moire Interferometry (PMI) were used to acquire wind tunnel model deformation measurements of the Northrop Grumman-built Smart Wing tested in the NASA Langley Transonic Dynamics Tunnel. The F18-E/F planform Smart Wing was outfitted with embedded shape memory alloys to actuate a seamless trailing edge aileron and flap, and an embedded torque tube to generate wing twist. The VMD system was used to obtain highly accurate deformation measurements at three spanwise locations along the main body of the wing, and at spanwise locations on the flap and aileron. The PMI system was used to obtain full-field wing shape and deformation measurements over the entire wing lower surface. Although less accurate than the VMD system, the PMI system revealed deformations occurring between VMD target rows indistinguishable by VMD. This paper presents the VMD and PMI techniques and discusses their application in the Smart Wing test.

Visualization of impact damage of composite plates by means of the Moire technique

NASA Technical Reports Server (NTRS)

Knauss, W. G.; Babcock, C. D.; Chai, H.

1980-01-01

The phenomenological aspects of propagation damage due to low velocity impact on heavily loaded graphite-epoxy composite laminates were investigated using high speed photography coupled with the moire fringe technique. High speed moire motion records of the impacted specimens are presented. The results provide information on the time scale and sequence of the failure process. While the generation of the initial damage cannot always be separated temporally from the spreading of the damage, the latter takes place on the average with a speed on the order of 200 m/sec.

A computer vision system for diagnosing scoliosis using moiré images.

PubMed

Batouche, M; Benlamri, R; Kholladi, M K

1996-07-01

For young people, scoliosis deformities are an evolving process which must be detected and treated as early as possible. The moiré technique is simple, inexpensive, not aggressive and especially convenient for detecting spinal deformations. Doctors make their diagnosis by analysing the symmetry of fringes obtained by such techniques. In this paper, we present a computer vision system for help diagnosing spinal deformations using noisy moiré images of the human back. The approach adopted in this paper consists of extracting fringe contours from moiré images, then localizing some anatomical features (the spinal column, lumbar hollow and shoulder blades) which are crucial for 3D surface generation carried out using Mota's relaxation operator. Finally, rules furnished by doctors are used to derive the kind of spinal deformation and to yield the diagnosis. The proposed system has been tested on a set of noisy moiré images, and the experimental result have shown its robustness and reliability for the recognition of most scoliosis deformities.

Deformation analysis of MEMS structures by modified digital moiré methods

NASA Astrophysics Data System (ADS)

Liu, Zhanwei; Lou, Xinhao; Gao, Jianxin

2010-11-01

Quantitative deformation analysis of micro-fabricated electromechanical systems is of importance for the design and functional control of microsystems. In this paper, two modified digital moiré processing methods, Gaussian blurring algorithm combined with digital phase shifting and geometrical phase analysis (GPA) technique based on digital moiré method, are developed to quantitatively analyse the deformation behaviour of micro-electro-mechanical system (MEMS) structures. Measuring principles and experimental procedures of the two methods are described in detail. A digital moiré fringe pattern is generated by superimposing a specimen grating etched directly on a microstructure surface with a digital reference grating (DRG). Most of the grating noise is removed from the digital moiré fringes, which enables the phase distribution of the moiré fringes to be obtained directly. Strain measurement result of a MEMS structure demonstrates the feasibility of the two methods.

Automatic Topography Using High Precision Digital Moire Methods

NASA Astrophysics Data System (ADS)

Yatagai, T.; Idesawa, M.; Saito, S.

1983-07-01

Three types of moire topographic methods using digital techniques are proposed. Deformed gratings obtained by projecting a reference grating onto an object under test are subjected to digital analysis. The electronic analysis procedures of deformed gratings described here enable us to distinguish between depression and elevation of the object, so that automatic measurement of 3-D shapes and automatic moire fringe interpolation are performed. Based on the digital moire methods, we have developed a practical measurement system, with a linear photodiode array on a micro-stage as a scanning image sensor. Examples of fringe analysis in medical applications are presented.

Surface profilometry using the incoherent self-imaging technique in reflection mode

NASA Astrophysics Data System (ADS)

Hassani, Khosrow; Nahal, Arashmid; Tirandazi, Negin

2018-01-01

In this paper, we introduce a highly sensitive and cost-effective surface profilometry technique based on the Lau self-imaging phenomenon in reflection mode, combined with the Moiré technique. Standard incoherent grating imaging with two Ronchi rulings is deployed to produce localized Fresnel pseudoimages, except that the light wavefront gets modulated after reflecting off the surface under test and before the final image forms. A third grating is superimposed on the pseudoimage to take advantage of the magnification property of the Moiré fringes and enhance the surface-induced modulations. A five-step phase-shifting technique is used to extract the 2D surface profile of the sample from the recorded Moiré patterns. To demonstrate our technique, we measure the profile of a 250 nm step-like metallic sample. The results show a few nanometer uncertainties, very good reproducibility, and agreement with other known optical and mechanical surface profilometry methods.

High contrast laser beam collimation testing using two proximately placed holographic optical elements

NASA Astrophysics Data System (ADS)

Rajkumar; Dubey, Rajiv; Debnath, Sanjit K.; Chhachhia, D. P.

2018-05-01

Accuracy in laser beam collimation is very important in systems used for precision measurements. The present work reports a technique for collimation testing of laser beams using two proximately placed holographic optical elements (HOEs). The required HOEs are designed and fabricated such that upon illumination with the test beam, they release two laterally sheared wavefronts, at desired angles from the directly transmitted beam, that superimpose each other to generate straight interference fringes. Deviation from the collimation of the test beam results in orientation of these otherwise horizontal fringes. The novelty of this setup comes from the fact that HOEs are lightweight, as well as easy to fabricate as compared to conventional wedge plates used for collimation testing, and generate high contrast fringes compared to other interferometry, holography, Talbot and Moiré based techniques in a compact manner. The proposed technique is experimentally validated by measuring the orientation of fringes by an angle of 16.4° when a collimating lens of focal length 200 mm is defocused by 600 μm. The accuracy in the setting of this collimation position is obtained to be 10 μm.

A comparative evaluation of in-plane shear test methods for laminated graphite-epoxy composites

NASA Technical Reports Server (NTRS)

Morton, John; Ho, Henjen

1992-01-01

The objectives were to evaluate popular shear test methods for various forms of graphite-epoxy composite materials and to determine the shear response of graphite-epoxy composites with various forms of fiber architecture. Numerical and full-field experimental stress analyses were performed on four shear test configurations for unidirectional and bidirectional graphite-epoxy laminates to assess the uniformity and purity of the shear stress (strain) fields produced in the specimen test section and to determine the material in-plane shear modulus and shear response. The test methods were the 10 deg off-axis, the +/- 45 deg tension, the Iosipescu V-notch, and a compact U-notch specimen. Specimens were prepared from AS4/3501-6 graphite-epoxy panels, instrumented with conventional strain gage rosettes and with a cross-line moire grating, and loaded in a convenient testing machine. The shear responses obtained for each test method and the two methods of specimen instrumentation were compared. In a second phase of the program the shear responses obtained from Iosipescu V-notch beam specimens were determined for woven fabric geometries of different weave and fiber architectures. Again the responses of specimens obtained from strain gage rosettes and moire interferometry were compared. Additional experiments were performed on a bidirectional cruciform specimen which was also instrumented with strain gages and a moire grating.

Optical image hiding based on chaotic vibration of deformable moiré grating

NASA Astrophysics Data System (ADS)

Lu, Guangqing; Saunoriene, Loreta; Aleksiene, Sandra; Ragulskis, Minvydas

2018-03-01

Image hiding technique based on chaotic vibration of deformable moiré grating is presented in this paper. The embedded secret digital image is leaked in a form of a pattern of time-averaged moiré fringes when the deformable cover grating vibrates according to a chaotic law of motion with a predefined set of parameters. Computational experiments are used to demonstrate the features and the applicability of the proposed scheme.

Calibration of an arbitrarily arranged projection moiré system for 3D shape measurement

NASA Astrophysics Data System (ADS)

Tang, Ying; Yao, Jun; Zhou, Yihao; Sun, Chen; Yang, Peng; Miao, Hong; Chen, Jubing

2018-05-01

An arbitrarily arranged projection moiré system is presented for three-dimensional shape measurement. We develop a model for projection moiré system and derive a universal formula expressing the relation between height and phase variation before and after we put the object on the reference plane. With so many system parameters involved, a system calibration technique is needed. In this work, we provide a robust and accurate calibration method for an arbitrarily arranged projection moiré system. The system no longer puts restrictions on the configuration of the optical setup. Real experiments have been conducted to verify the validity of this method.

Characterization technique for detection of atom-size crystalline defects and strains using two-dimensional fast-Fourier-transform sampling Moiré method

NASA Astrophysics Data System (ADS)

Kodera, Masako; Wang, Qinghua; Ri, Shien; Tsuda, Hiroshi; Yoshioka, Akira; Sugiyama, Toru; Hamamoto, Takeshi; Miyashita, Naoto

2018-04-01

Recently, we have developed a two-dimensional (2D) fast-Fourier-transform (FFT) sampling Moiré technique to visually and quantitatively determine the locations of minute defects in a transmission electron microscopy (TEM) image. We applied this technique for defect detection with GaN high electron mobility transistor (HEMT) devices, and successfully and clearly visualized atom-size defects in AlGaN/GaN crystalline structures. The defect density obtained in the AlGaN/GaN structures is ∼1013 counts/cm2. In addition, we have successfully confirmed that the distribution and number of defects closely depend on the process conditions. Thus, this technique is quite useful for a device development. Moreover, the strain fields in an AlGaN/GaN crystal were effectively calculated with nm-scale resolution using this method. We also demonstrated that this sampling Moiré technique is applicable to silicon devices, which have principal directions different from those of AlGaN/GaN crystals. As a result, we believe that the 2D FFT sampling Moiré method has great potential applications to the discovery of new as yet unknown phenomena occurring between the characteristics of a crystalline material and device performance.

Full-Field Stress Determination Around Circular Discontinuity in a Tensile-Loaded Plate using x-displacements Only

NASA Astrophysics Data System (ADS)

Baek, Tae Hyun; Chung, Tae Jin; Panganiban, Henry

The significant effects of stress raisers demand well-defined evaluation techniques to accurately determine the stress along the geometric boundary. A simple and accurate method for the determination of stress concentration around circular geometric discontinuity in a tensile-loaded plate is illustrated. The method is based on the least-squares technique, mapping functions, and a complex power series representation (Laurent series) of the stress functions for the calculation of tangential stress around the hole. Traction-free conditions were satisfied at the geometric discontinuity using conformal mapping and analytic continuation. In this study, we use only a relatively small amount of x-component displacement data of points away from the discontinuity of concern with their respective coordinates. Having this information we can easily obtain full-field stresses at the edge of the geometric discontinuity. Excellent results were obtained when the number of terms of the power series expansions, m=1. The maximum stress concentration calculation results using the present method and FEM using ANSYS agree well by less than one per cent difference. Experimental advantage of the method underscores the use of relatively small amount of data which are conveniently determined being away from the edge. Moreover, the small amount of measured input data needed affords the approach suitable for applications such as the multi-parameter concept used to obtain stress intensity factors from measured data. The use of laser speckle interferometry and moiré interferometry are also potential future related fields since the optical system for one-directional measurement is much simple.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liao, Yubo; School of Physics and Electronic Information Science, Gannan Normal University, Ganzhou 341000; Lei, Yunfei

An image converter tube with a magnetic lens was used to obtain static images of moiré fringes formed by electron beam. These moiré fringes are formed due to the interference between the anode mesh and the photocathode containing slits of various spatial frequencies. Moiré fringes are observed at an accelerating voltage of 3.5 kV requiring the magnetic excitation condition of ∼550 ampere-turns. Not only the features of the fringes are analyzed but also the change of fringe spacing as a function of the rotation angle is investigated. The experimental results are found well in agreement with the theoretical analysis. By changingmore » the rotation angle or adjusting the excitation condition of the magnetic lens, we were able to record parallel moiré and secondary moiré fringes too. The secondary moiré fringes can be observed in the rotation angle range of −39.5° to −50.6°. The theoretical analysis indicates that the secondary moiré is formed by the interference between the photocathode slits and the 2-D periodic structure of the anode mesh. Combining our proposed moiré method with the pulse-dilation technique may potentially open the door for future applications, in various fields including, but not limited to, ultrafast electrical pulse diagnostics.« less

Measure of displacement around holes in composite plates subjected to quasi-static compression

NASA Technical Reports Server (NTRS)

Duke, J. C., Jr.; Post, D.; Czarnek, R.; Asundi, A.

1986-01-01

Contour maps of thickness changes were obtained for three quasi-isotropic graphite-epoxy plates with central holes, loaded in compression. Thickness changes were determined for six load increments from nearly zero to within a few percent of the failure load. The largest change of thickness occurred near the hole but not at the boundary of the hole. Below 90 percent of the failure load, the thickness changes were nearly proportional to load. Irregularities of thickness changes occurred in zones of compressive stresses and they were attributed to localized fiber buckling. A new optical technique was developed to measure thickness changes with high sensitivity. It utilizes a comparatively simple means of holographic interferometry on both sides of the specimen, followed by additive moire to obtain thickness changes as the sum of the out-of-plane displacements. Sensitivity was 12.5 x 10 to the -6 power in. per fringe order. The fringe patterns represent thickness changes uniquely, even when specimen warpage and consequent out-of-plane displacements are very large.

Fringe pattern information retrieval using wavelets

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Patimo, Caterina; Manicone, Pasquale D.; Lamberti, Luciano

2005-08-01

Two-dimensional phase modulation is currently the basic model used in the interpretation of fringe patterns that contain displacement information, moire, holographic interferometry, speckle techniques. Another way to look to these two-dimensional signals is to consider them as frequency modulated signals. This alternative interpretation has practical implications similar to those that exist in radio engineering for handling frequency modulated signals. Utilizing this model it is possible to obtain frequency information by using the energy approach introduced by Ville in 1944. A natural complementary tool of this process is the wavelet methodology. The use of wavelet makes it possible to obtain the local values of the frequency in a one or two dimensional domain without the need of previous phase retrieval and differentiation. Furthermore from the properties of wavelets it is also possible to obtain at the same time the phase of the signal with the advantage of a better noise removal capabilities and the possibility of developing simpler algorithms for phase unwrapping due to the availability of the derivative of the phase.

Stress and efficiency studies in EFG

NASA Technical Reports Server (NTRS)

1986-01-01

The goals of this program were: (1) to define minimum stress configurations for silicon sheet growth at high speeds; (2) to quantify dislocation electrical activity and their limits on minority carrier diffusion length in deformed silicon; and (3) to study reasons for degradation of lifetime with increases in doping level in edge-defined film-fed growth (EFG) materials. A finite element model was developed for calculating residual stress with plastic deformation. A finite element model was verified for EFG control variable relationships to temperature field of the sheet to permit prediction of profiles and stresses encountered in EFG systems. A residual stress measurement technique was developed for finite size EFG material blanks using shadow Moire interferometry. Transient creep response of silicon was investigated in the temperature range between 800 and 1400 C in strain and strain regimes of interest in stress analysis of sheet growth. Quantitative relationships were established between minority carrier diffusion length and dislocation densities using Electron Beam Induced Current (EBIC) measurement in FZ silicon deformed in four point bending tests.

Investigation of a Moire Based Crack Detection Technique for Propulsion Health Monitoring

NASA Technical Reports Server (NTRS)

Woike, Mark R.; Abudl-Aziz, Ali; Fralick, Gustave C.; Wrbanek, John D.

2012-01-01

The development of techniques for the health monitoring of the rotating components in gas turbine engines is of major interest to NASA s Aviation Safety Program. As part of this on-going effort several experiments utilizing a novel optical Moir based concept along with external blade tip clearance and shaft displacement instrumentation were conducted on a simulated turbine engine disk as a means of demonstrating a potential optical crack detection technique. A Moir pattern results from the overlap of two repetitive patterns with slightly different periods. With this technique, it is possible to detect very small differences in spacing and hence radial growth in a rotating disk due to a flaw such as a crack. The experiment involved etching a circular reference pattern on a subscale engine disk that had a 50.8 mm (2 in.) long notch machined into it to simulate a crack. The disk was operated at speeds up to 12 000 rpm and the Moir pattern due to the shift with respect to the reference pattern was monitored as a means of detecting the radial growth of the disk due to the defect. In addition, blade displacement data were acquired using external blade tip clearance and shaft displacement sensors as a means of confirming the data obtained from the optical technique. The results of the crack detection experiments and its associated analysis are presented in this paper.

Moire Topography For The Detection Of Orthopaedic Defects

NASA Astrophysics Data System (ADS)

Kamal, Syed A.; Lindseth, Richard E.

1981-02-01

Moire topography is applied for the follow-up of scoliosis patients. The results are then compared with the X-rays. A special lamp and scale arrangement is utilized for patient alignment. It is suggested that this technique will be used for the detection of all orthopaedic defects.

Interferometric reflection moire

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Combell, Olivier

1995-06-01

A new reflection moire technique is introduced in this paper. The basic equations that relate the measurement of slopes to the basic geometric and optical parameters of the system are derived. The sensitivity and accuracy of the method are discussed. Examples of application to the study of silicon wafers and electronic chips are given.

Visualization and automatic detection of defect distribution in GaN atomic structure from sampling Moiré phase.

PubMed

Wang, Qinghua; Ri, Shien; Tsuda, Hiroshi; Kodera, Masako; Suguro, Kyoichi; Miyashita, Naoto

2017-09-19

Quantitative detection of defects in atomic structures is of great significance to evaluating product quality and exploring quality improvement process. In this study, a Fourier transform filtered sampling Moire technique was proposed to visualize and detect defects in atomic arrays in a large field of view. Defect distributions, defect numbers and defect densities could be visually and quantitatively determined from a single atomic structure image at low cost. The effectiveness of the proposed technique was verified from numerical simulations. As an application, the dislocation distributions in a GaN/AlGaN atomic structure in two directions were magnified and displayed in Moire phase maps, and defect locations and densities were detected automatically. The proposed technique is able to provide valuable references to material scientists and engineers by checking the effect of various treatments for defect reduction. © 2017 IOP Publishing Ltd.

An Extension of Holographic Moiré to Micromechanics

NASA Astrophysics Data System (ADS)

Sciammarella, C. A.; Sciammarella, F. M.

The electronic Holographic Moiré is an ideal tool for micromechanics studies. It does not require a modification of the surface by the introduction of a reference grating. This is of particular advantage when dealing with materials such as solid propellant grains whose chemical nature and surface finish makes the application of a reference grating very difficult. Traditional electronic Holographic Moiré presents some difficult problems when large magnifications are needed and large rigid body motion takes place. This paper presents developments that solves these problems and extends the application of the technique to micromechanics.

Integrated Methodology for Adhesive Bonded Joint Life Predictions.

DTIC Science & Technology

1982-11-01

holography with fictitious fringe-moire’, as pioneered and perfected over the last few years by Prof. Sciammarella and his students albeit on relatively... Sciammarella et al. have very recently solved this problem by using the holographic moire’ technique in rIAI ime combined with closed circuit TV (Ref. 74... Sciammarella et al. The in-plane (x) displacements are given by a moire’ 129 -- ~ -- ~ --.- ~4-4 00 e’J 00 00 wI 4. *~:1 r. .00 0 0 0 d u0 02( 1 0 r4

Evaluation of crystallographic strain, rotation and defects in functional oxides by the moiré effect in scanning transmission electron microscopy.

PubMed

Naden, A B; O'Shea, K J; MacLaren, D A

2018-04-20

Moiré patterns in scanning transmission electron microscopy (STEM) images of epitaxial perovskite oxides are used to assess strain and defect densities over fields of view extending over several hundred nanometers. The patterns arise from the geometric overlap of the rastered STEM electron beam and the samples' crystal periodicities and we explore the emergence and application of these moiré fringes for rapid strain analysis. Using the epitaxial functional oxide perovskites BiFeO 3 and Pr 1-x Ca x MnO 3 , we discuss the impact of large degrees of strain on the quantification of STEM moiré patterns, identify defects in the fringe patterns and quantify strain and lattice rotation. Such a wide-area analysis of crystallographic strain and defects is crucial for developing structure-function relations of functional oxides and we find the STEM moiré technique to be an attractive means of structural assessment that can be readily applied to low dose studies of damage sensitive crystalline materials.

Evaluation of crystallographic strain, rotation and defects in functional oxides by the moiré effect in scanning transmission electron microscopy

NASA Astrophysics Data System (ADS)

Naden, A. B.; O'Shea, K. J.; MacLaren, D. A.

2018-04-01

Moiré patterns in scanning transmission electron microscopy (STEM) images of epitaxial perovskite oxides are used to assess strain and defect densities over fields of view extending over several hundred nanometers. The patterns arise from the geometric overlap of the rastered STEM electron beam and the samples’ crystal periodicities and we explore the emergence and application of these moiré fringes for rapid strain analysis. Using the epitaxial functional oxide perovskites BiFeO3 and Pr1-x Ca x MnO3, we discuss the impact of large degrees of strain on the quantification of STEM moiré patterns, identify defects in the fringe patterns and quantify strain and lattice rotation. Such a wide-area analysis of crystallographic strain and defects is crucial for developing structure-function relations of functional oxides and we find the STEM moiré technique to be an attractive means of structural assessment that can be readily applied to low dose studies of damage sensitive crystalline materials.

Large radius of curvature measurement based on the evaluation of interferogram-quality metric in non-null interferometry

NASA Astrophysics Data System (ADS)

Yang, Zhongming; Dou, Jiantai; Du, Jinyu; Gao, Zhishan

2018-03-01

Non-null interferometry could use to measure the radius of curvature (ROC), we have presented a virtual quadratic Newton rings phase-shifting moiré-fringes measurement method for large ROC measurement (Yang et al., 2016). In this paper, we propose a large ROC measurement method based on the evaluation of the interferogram-quality metric by the non-null interferometer. With the multi-configuration model of the non-null interferometric system in ZEMAX, the retrace errors and the phase introduced by the test surface are reconstructed. The interferogram-quality metric is obtained by the normalized phase-shifted testing Newton rings with the spherical surface model in the non-null interferometric system. The radius curvature of the test spherical surface can be obtained until the minimum of the interferogram-quality metric is found. Simulations and experimental results are verified the feasibility of our proposed method. For a spherical mirror with a ROC of 41,400 mm, the measurement accuracy is better than 0.13%.

Deferred electronic heterodyne moire deflectometry: A method for transient density fields measurement

NASA Technical Reports Server (NTRS)

Stricker, Josef

1989-01-01

Effects of spherical aberrations of the mirror used in the moire system on the angular resolution of the system are investigated. It is shown that the spherical aberrations may reduce significantly the performance of the conventional moire deflectometer. However, due to the heterodyne procedure, this is not the case with the heterodyne moire system. A moire system with a constant speed moving grating is demonstrated. It is shown that the system readout is linear and the system does not need calibration. In addition, the repeatability of the measurements is improved in this system as compared to the sinusoidally moving grating setup. The problem of the photographic plates alignment is solved by using a mechanical system in which the plate is held firmly throughout the experiment and accurately replaced after removing for photographic processing. The effect of a circular detector's aperture size on readout was tested. It is shown that the spatial phase variations, observed when scanning along a straight moire fringe, may considerably be reduced. At present we may say that both the on-line and the deferred heterodyne moire techniques may reliably be used. The errors of phase readings are 1 deg and 5 deg for the on-line and deferred methods. The total error due to subtraction of two readings at each position is, therefore, 1.4 deg and 7 deg, respectively. Further research for improving the deferred system is suggested.

Trochoidal X-ray Vector Radiography: Directional dark-field without grating stepping

NASA Astrophysics Data System (ADS)

Sharma, Y.; Bachche, S.; Kageyama, M.; Kuribayashi, M.; Pfeiffer, F.; Lasser, T.; Momose, A.

2018-03-01

X-ray Vector Radiography (XVR) is an imaging technique that reveals the orientations of sub-pixel sized structures within a sample. Several dark-field radiographs are acquired by rotating the sample around the beam propagation direction and stepping one of the gratings to several positions for every pose of the sample in an X-ray grating interferometry setup. In this letter, we present a method of performing XVR of a continuously moving sample without the need of any grating motion. We reconstruct the orientations within a sample by analyzing the change in the background moire fringes caused by the sample moving and simultaneously rotating in plane (trochoidal trajectory) across the detector field-of-view. Avoiding the motion of gratings provides significant advantages in terms of stability and repeatability, while the continuous motion of the sample makes this kind of system adaptable for industrial applications such as the scanning of samples on a conveyor belt. Being the first step in the direction of utilizing advanced sample trajectories to replace grating motion, this work also lays the foundations for a full three dimensional reconstruction of scattering function without grating motion.

Instantaneous Doppler Global Velocimetry Measurements of a Rotor Wake: Lessons Learned

NASA Technical Reports Server (NTRS)

Meyers, James; Fleming, Gary A.; Gorton, Susan Althoff; Berry, John D.

1998-01-01

A combined Doppler Global Velocimetry (DGV) and Projection Moir Interferometry (PMI) investigation of a helicopter rotor wake flow field and rotor blade deformation is presented. The three-component DGV system uses a single-frequency, frequency-doubled Nd:YAG laser to obtain instantaneous velocity measurements in the flow. The PMI system uses a pulsed laser-diode bar to obtain blade bending and twist measurements at the same instant that DGV measured the flow. The application of pulse lasers to DGV and PMI in large-scale wind tunnel applications represents a major step forward in the development of these technologies. As such, a great deal was learned about the difficulties of using these instruments to obtain instantaneous measurements in large facilities. Laser speckle and other image noise in the DGV data images were found to be traceable to the Nd:YAG laser. Although image processing techniques were used to virtually eliminate laser speckle noise, the source of low-frequency image noise is still under investigation. The PMI results agreed well with theoretical predictions of blade bending and twist.

SU-F-P-48: The Quantitative Evaluation and Comparison of Image Distortion and Loss of X-Ray Images Between Anti-Scattered Grid and Moire Compensation Processing in Digital Radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, W; Jung, J; Kang, Y

Purpose: To quantitatively analyze the influence image processing for Moire elimination has in digital radiography by comparing the image acquired from optimized anti-scattered grid only and the image acquired from software processing paired with misaligned low-frequency grid. Methods: Special phantom, which does not create scattered radiation, was used to acquire non-grid reference images and they were acquired without any grids. A set of images was acquired with optimized grid, aligned to pixel of a detector and other set of images was acquired with misaligned low-frequency grid paired with Moire elimination processing algorithm. X-ray technique used was based on consideration tomore » Bucky factor derived from non-grid reference images. For evaluation, we analyze by comparing pixel intensity of acquired images with grids to that of reference images. Results: When compared to image acquired with optimized grid, images acquired with Moire elimination processing algorithm showed 10 to 50% lower mean contrast value of ROI. Severe distortion of images was found with when the object’s thickness was measured at 7 or less pixels. In this case, contrast value measured from images acquired with Moire elimination processing algorithm was under 30% of that taken from reference image. Conclusion: This study shows the potential risk of Moire compensation images in diagnosis. Images acquired with misaligned low-frequency grid results in Moire noise and Moire compensation processing algorithm used to remove this Moire noise actually caused an image distortion. As a result, fractures and/or calcifications which are presented in few pixels only may not be diagnosed properly. In future work, we plan to evaluate the images acquired without grid but based on 100% image processing and the potential risks it possesses.« less

Proceedings of the XXII A.I.VE.LA. National Meeting

NASA Astrophysics Data System (ADS)

Primo Tomasini, Enrico

2015-11-01

A.I.VE.LA. - the Italian Association of Laser Velocimetry and non-invasive diagnostics - is a non-profit cultural association whose objective is to promote and support research in the field of non-contact or minimally invasive measurement techniques, particularly electromagnetic-based techniques and optical techniques. Through its Annual Meeting, AIVELA aims to create an active and stimulating forum where current research results and technical advances can be exchanged and the development of new systems for laboratory use, field testing and industrial application can be promoted. The techniques covered include Laser Doppler Anemometry - LDA, Phase Doppler Anemometry - PDA, Image Velocimetry - PIV, Flow visualization techniques, Spectroscopic measurement techniques (LIF, Raman, etc.), Laser Doppler Vibrometry - LDV, Speckle Pattern Interferometry - ESPI, Holographic techniques, Shearography, Digital Image Correlation - DIC, Moiré techniques, Structured light techniques, Infrared imaging, Photoelasticity, Image based measurement techniques, Ultrasonic sensing, Acoustic and Aeroacoustic measurements, etc. The first Annual Meeting was held back in October 1992 and since then there has been a large consensus among the research and scientific communities that the papers presented at the event are of a high scientific interest. The XXII AIVELA Annual Meeting was held at the Faculty of Engineering of University of Rome Tor Vergata on 15-16 December 2014 and was organised in collaboration with the International Master Courses in "Protection Against CBRNe Events". This volume contains a selection of the papers presented at the event. The detailed Programme of the Meeting can be found at: http://www.aivela.org/XXII_Convegno/index.html Trusting our Association and its initiatives will meet your interest, I wish to thank you in advance for your kind attention and hope to meet you soon at one of our events.

Inspection of arterial-induced skin vibration by Moire fringe with two-dimensional continuous wavelet transform

NASA Astrophysics Data System (ADS)

Wang, Chun-Hsiung; Chiu, Shih-Yung; Hsu, Yu-Hsiang; Lee, Shu-Sheng; Lee, Chih-Kung

2017-06-01

A non-contact arterial-induced skin vibration inspection system is implemented. This optical metrology system is constructed with shadow Moiré configuration and the fringe analysis algorithm. Developed with the Region of Interested (ROI) capturing technique and the Two-dimensional Wavelet Transform (2D-CWT) method, this algorithm is able to retrieve the height-correlated phase information from the shadow Moiré fringe patterns. Using a commercial video camera or a CMOS image sensor, this system could monitor the skin-vibration induced by the cyclic deformation of inner layered artery. The cross-sectional variation and the rhythm of heart cycle could be continuously measured for health monitoring purposes. The average vibration amplitude of the artery at the wrist ranges between 20 μm and 50 μm, which is quite subtle comparing with the skin surface structure. Having the non-stationary motion of human body, the traditional phase shifting (PS) technique can be very unstable due to the requirement of several frames of images, especially for case that artery is continuously pumping. To bypass this fundamental issue, the shadow Moiré technique is introduced to enhance the surface deformation characteristic. And the phase information is retrieved by the means of spectrum filtering instead of PS technique, which the phase is calculated from intensity maps of multiple images. The instantaneous surface can therefore be reconstructed individually from each frame, enabling the subtle arterial-induced skin vibration measurement. The comparative results of phase reconstruction between different fringe analysis algorithms will be demonstrated numerically and experimentally. And the electrocardiography (ECG) results will used as the reference for the validity of health monitoring potential of the non-contact arterial-induced skin vibration inspection system.

An Introduction to Moire Methods with Applications in Composite Materials

DTIC Science & Technology

1992-08-01

including hardware and software requirements are discussed by Ranson, 19 Sciammarella , 2 0 Chanudry,2 1 Ning,2 2 and Lee. 23 Other computation techniques...variations in material fabrication processes. 9 Dynamic applications of moire were done by Armenakas and Sciammarella , 70 Epstein, Deason, and...Abdallah,71, 72 as well as Hsu, Liu, Chiang, and Anastasi. 73 Armenakas and Sciammarella examined the response of glass/epoxy specimens to high strain rates

Three-dimensional effects in nonlinear fracture explored with interferometry

NASA Astrophysics Data System (ADS)

Pfaff, Richard D.

The prospects for understanding fracture mechanics in terms of a general material constitutive description are explored. The effort consists of three distinct components.First, optical interferometry, in its various forms (Twyman-Green, diffraction moire, etc.), can potentially be used under a wide range of conditions to very accurately measure the displacement and strain fields associated with the deformation surrounding a cracktip. To broaden the range of fracture problems to which interferometry may be applied, certain of the necessary experimental improvements have been developed:1. High speed camera designs capable of extremely high (> 10(9) frames/second) framing rates with large array sizes, (> 4000 x 4000 pixels per frame) so that the application of optical techniques to solid mechanics may be considered without limitation on the rate of deformation.2. An accurate and adaptable device for dynamic loading of fracture specimens to high load levels utilizing electromagnetic (Lorentz force) loading with ultrahigh (> 2,000,000 Amp/cm(2)) current flux densities.3. Implementation of high sensitivity (2 nm), large range (2 nm x 3,200,000) interferometry achieved with wide field array sizes of 50,000 x 50,000 and 8 bit gray scale (error restricted to 1 bit) for surface deformation measurements on fracture specimens.Second, functional descriptions for certain aspects of the displacement fields associated with fracture specimens are developed. It is found that the fully three-dimensional crack tip field surrounding a through-thickness crack in a plate of elastic-plastic material shows a hierarchical structure of organization and that the primary aspects of the deformation field would seem to have a relatively simple form of expression if the deformation is viewed in a properly normalized form.Third, a comparison is made between interferometrically measured surface displacements for a notched 3-point-bend speciemn of a ductile heat treatment of 4340 steel and a numerical simulation of the specimen based on a material constitutive description determined from uniaxial tests performed on the same material. The small but finite notch tip radius (0.15 mm) fabricated by a wire-cutting electrical discharge machine allows one to explore the limits of applicability of standard continuum plasticity theories without involving a process zone model for the very near tip region extent in a cracked specimen geometry.

Nonscanning Moiré deflectometry for measurement of nonlinear refractive index and absorption coefficient of liquids.

PubMed

Farahani, Shahrzad Shahrabi; Madanipour, Khosro; Koohian, Ata

2017-05-01

In this work, a nonscanning measurement technique is presented for determining the nonlinear refractive index and absorption coefficient of liquid media based on Moiré deflectometry. In the proposed method two lasers are used: a low power, wide beam as probe and a high power with specific wavelength as a pump. Interaction of the pump laser beam with the nonlinear sample changes the refractive index, which leads to change in convergence/divergence of the collimated incident probe laser beam. The induced deflection is monitored by Moiré deflectometry. If the pump laser has a Gaussian intensity profile, the refractive index profile of the sample is Gaussian, too. Measuring the deflection angle of the probe beam by Moiré fringes deflection, and by using the inverse Abel transform integral, the refractive index profile and nonlinear refractive index can be determined. This method is fast, easy, and insensitive to environmental noise and allows real-time measurement. Also, the refractive index profile of the interacted medium with pump laser can be achieved by this technique. As a liquid sample, a DCJ dye in water solution was studied. The value of nonlinear refractive index, n₂, and absorption coefficient, α, were obtained -2.54×10^-4  cm² w^-1 and 1.368  cm^-1, respectively.

A Wafer-Bonded, Floating Element Shear-Stress Sensor Using a Geometric Moire Optical Transduction Technique

NASA Technical Reports Server (NTRS)

Horowitz, Stephen; Chen, Tai-An; Chandrasekaran, Venkataraman; Tedjojuwono, Ken; Cattafesta, Louis; Nishida, Toshikazu; Sheplak, Mark

2004-01-01

This paper presents a geometric Moir optical-based floating-element shear stress sensor for wind tunnel turbulence measurements. The sensor was fabricated using an aligned wafer-bond/thin-back process producing optical gratings on the backside of a floating element and on the top surface of the support wafer. Measured results indicate a static sensitivity of 0.26 microns/Pa, a resonant frequency of 1.7 kHz, and a noise floor of 6.2 mPa/(square root)Hz.

X-ray Moiré deflectometry using synthetic reference images

DOE PAGES

Stutman, Dan; Valdivia, Maria Pia; Finkenthal, Michael

2015-06-25

Moiré fringe deflectometry with grating interferometers is a technique that enables refraction-based x-ray imaging using a single exposure of an object. To obtain the refraction image, the method requires a reference fringe pattern (without the object). Our study shows that, in order to avoid artifacts, the reference pattern must be exactly matched in phase with the object fringe pattern. In experiments, however, it is difficult to produce a perfectly matched reference pattern due to unavoidable interferometer drifts. We present a simple method to obtain matched reference patterns using a phase-scan procedure to generate synthetic Moiré images. As a result, themore » method will enable deflectometric diagnostics of transient phenomena such as laser-produced plasmas and could improve the sensitivity and accuracy of medical phase-contrast imaging.« less

Image communication scheme based on dynamic visual cryptography and computer generated holography

NASA Astrophysics Data System (ADS)

Palevicius, Paulius; Ragulskis, Minvydas

2015-01-01

Computer generated holograms are often exploited to implement optical encryption schemes. This paper proposes the integration of dynamic visual cryptography (an optical technique based on the interplay of visual cryptography and time-averaging geometric moiré) with Gerchberg-Saxton algorithm. A stochastic moiré grating is used to embed the secret into a single cover image. The secret can be visually decoded by a naked eye if only the amplitude of harmonic oscillations corresponds to an accurately preselected value. The proposed visual image encryption scheme is based on computer generated holography, optical time-averaging moiré and principles of dynamic visual cryptography. Dynamic visual cryptography is used both for the initial encryption of the secret image and for the final decryption. Phase data of the encrypted image are computed by using Gerchberg-Saxton algorithm. The optical image is decrypted using the computationally reconstructed field of amplitudes.

Ultrasonic analysis of Kevlar-epoxy filament wound structures

NASA Astrophysics Data System (ADS)

Brosey, W. D.

1985-07-01

Composite structures are often desirable for their strength and weight characteristics. Since composites are not as well characterized mechanically as metallic or ceramic structures, much work has been performed at the Oak Ridge Y-12 Plant to obtain that characterization and to develop methods of determining the mechanical properties of a composite nondestructively. Most of the work to date has been performed on nonenclosed structures. One notable exception has been the holographic evaluation of spherical Kevlar-epoxy composite pressure vessels. Several promising nondestructive evaluation techniques have been used to locate flaws and predict the integrity of the composite. Several of these include thermography, Moire interferometry, ultrasonic stress wave factor, ultrasonic C-scan image enhancement, radiography, and nuclear magnetic resonance. As a first step in this transfer and development of NDE techniques, known defects were placed within spherical Kevlar-epoxy, filament-wound test specimens to determine the extent to which they could be detected. These defects included Teflon shim-simulated delaminations, macrosphere-simulated voids, dry-band sets, variable tension, Kevlar 29 fiber instead of the higher strength Kevlar 40 fiber, and an alternate high-void-content winding pattern. Ultrasonic waveform analysis was performed in both the time and frequency domains to determine the detectability and locatability of structural flaws within the composite. Preparation has been made at Virginia Polytechnic Institute and State University and at the University of Delaware, to examine the specimens using various NDE techniques. This work is a compilation of interim project reports in partial fulfillment of the contracts between Virginia Polytechnic Institute and State University, the University of Delaware, and Y-12 Plant.

Theoretical study of the properties of X-ray diffraction moiré fringes. I

PubMed Central

Yoshimura, Jun-ichi

2015-01-01

A detailed and comprehensive theoretical description of X-ray diffraction moiré fringes for a bicrystal specimen is given on the basis of a calculation by plane-wave dynamical diffraction theory. Firstly, prior to discussing the main subject of the paper, a previous article [Yoshimura (1997 ▸). Acta Cryst. A53, 810–812] on the two-dimensionality of diffraction moiré patterns is restated on a thorough calculation of the moiré interference phase. Then, the properties of moiré fringes derived from the above theory are explained for the case of a plane-wave diffraction image, where the significant effect of Pendellösung intensity oscillation on the moiré pattern when the crystal is strained is described in detail with theoretically simulated moiré images. Although such plane-wave moiré images are not widely observed in a nearly pure form, knowledge of their properties is essential for the understanding of diffraction moiré fringes in general. PMID:25970298

Directed-assembled multi-band moiré plasmonic metasurfaces

NASA Astrophysics Data System (ADS)

Nagavalli Yogeesh, Maruthi; Wu, Zilong; Li, Wei; Akinwande, Deji; Zheng, Yuebing

With the large number of component sets and high rotational symmetry, plasmonic metamaterials with moiré patterns can support multiple plasmonic modes for multi-functional applications. Herein, we introduce moiré plasmonic metasurfaces using both gold and graphene, by a recently developed directed-assembled method known as moiré nanosphere lithography (MNSL). The graphene moiré metasurfaces show multiple and tunable resonance modes in the mid-infrared wavelength regime. The number and wavelength of the resonance modes can be tuned by controlling the moiré patterns, which can be easily achieved by changing the relative in-plane rotation angle during MNSL. Furthermore, we have designed a metal-insulator-metal (MIM) patch structure with a thin Au moiré metasurface layer and an optically thick Au layer separated by a dielectric spacer layer. Benefiting from the combination of moiré patterns and field enhancement from the MIM configuration, the moiré metasurface patch exhibits strong broadband absorption in the NIR ( 1.3 μm) and MIR ( 5 μm) range. The dual-band optical responses make moiré metasurface patch a multi-functional platform for surface-enhanced infrared spectroscopy, optical capture and patterning of bacteria, and photothermal denaturation of proteins.

Evolution of the fracture process zone in high-strength concrete under different loading rates

NASA Astrophysics Data System (ADS)

Yu, R. C.; Zhang, X.; Ruiz, G.; Tarifa, M.; Cámara, M.

2010-06-01

For cementitious materials, the inelastic zone around a crack tip is termed as fracture process zone (FPZ) and dominated by complicated mechanism, such as microcracking, crack deflection, bridging, crack face friction, crack tip blunting by voids, crack branching, and so on. Due to the length of the FPZ is related with the characteristic length of the cementitious materials, the size, extent and location of the FPZ has been the object of countless research efforts for several decades. For instance, Cedolin et al. [1] have used an optical method based on the moiré interferometry to determine FPZ in concrete. Castro-Montero et al. [2] have applied the method of holographic interferometry to mortar to study the extension of the FPZ. The advantage of the interferometry method is that the complete FPZ can be directly observed on the surface of the sample. Swartz et al. [3] has adopted the dye penetration technique to illustrate the changing patterns observed as the crack progress from the tensile side to the compression side of the beam. Moreover, acoustic emission (AE) is also an experimental technique well suited for monitoring fracture process. Haidar et al. [4] and Maji et al. [5] have studied the relation between acoustic emission characteristics and the properties of the FPZ. Compared with the extensive research on properties of the FPZ under quasi-static loading conditions, much less information is available on its dynamic characterization, especially for high-strength concrete (HSC). This paper presents the very recent results of an experimental program aimed at disclosing the loading rate effect on the size and velocity of the (FPZ) in HSC. Eighteen three-point bending specimens were conducted under a wide range of loading rates from from 10-4 mm/s to 103 mm/s using either a servo-hydraulic machine or a self-designed drop-weight impact device. The beam dimensions were 100 mm 100 mm in cross section, and 420 mm in length. The initial notch-depth ratio was approximately 0.5, and the span was fixed at 300 mm during the tests. Four strain gauges mounted along the ligament of the specimen were used to measure the FPZ size. Surprisingly, the FPZ size remains almost constant (around 20 mm) when the loading rate varies seven orders of magnitude. This is clearly different from NSC, in which the FPZ size actually decreased with loading rate.

Bibliography of spatial interferometry in optical astronomy

NASA Technical Reports Server (NTRS)

Gezari, Daniel Y.; Roddier, Francois; Roddier, Claude

1990-01-01

The Bibliography of Spatial Interferometry in Optical Astronomy is a guide to the published literature in applications of spatial interferometry techniques to astronomical observations, theory and instrumentation at visible and infrared wavelengths. The key words spatial and optical define the scope of this discipline, distinguishing it from spatial interferometry at radio wavelengths, interferometry in the frequency domain applied to spectroscopy, or more general electro-optics theoretical and laboratory research. The main bibliography is a listing of all technical articles published in the international scientific literature and presented at the major international meetings and workshops attended by the spatial interferometry community. Section B summarizes publications dealing with the basic theoretical concepts and algorithms proposed and applied to optical spatial interferometry and imaging through a turbulent atmosphere. The section on experimental techniques is divided into twelve categories, representing the most clearly identified major areas of experimental research work. Section D, Observations, identifies publications dealing specifically with observations of astronomical sources, in which optical spatial interferometry techniques have been applied.

Indentation measurements on the eardrum with automated projection moiré profilometry

NASA Astrophysics Data System (ADS)

Buytaert, J. A. N.; Aernouts, J. E. F.; Dirckx, J. J. J.

2009-03-01

Computer modeling of middle ear mechanics is an important tool to investigate its complex behavior, but correct mechanical and elastic parameters are needed to obtain realistic simulations. A possible way to determine eardrum elasticity in situ is the use of point indentation measurements. The eardrum is, however, a small fragile membrane, so a non-contacting high-resolution technique is needed to measure the shape change caused by point indentation. We have developed a projection moiré interferometer combined with an indentation actuator and a high-resolution force sensor. The apparatus applies deformations up to 1 mm with a resolution of 1 μm, while the indentation force is measured with a resolution better than 1 mN. The moiré setup delivers height data on 512×512 points through phase-shifting, with a height resolution of 15 μm. Shape recordings are made on a rabbit eardrum at different indentation distances, and indentation force is recorded simultaneously.

Electron density and effective atomic number (Zeff) determination through x-ray Moiré deflectometry

NASA Astrophysics Data System (ADS)

Valdivia Leiva, Maria Pia; Stutman, Dan; Finkenthal, Michael

2014-10-01

Talbot-Lau based Moiré deflectometry is a powerful density diagnostic capable of delivering refraction information and attenuation from a single image, through the accurate detection of X-ray phase-shift and intensity. The technique is able to accurately measure both the real part of the index of refraction δ (directly related to electron density) and the attenuation coefficient μ of an object placed in the x-ray beam. Since the atomic number Z (or Zeff for a composite sample) is proportional to these quantities, an elemental map of the effective atomic number can be obtained with the ratio of the phase and the absorption image. The determination of Zeff from refraction and attenuation measurements with Moiré deflectometry could be of high interest in various fields of HED research such as shocked materials and ICF experiments as Zeff is linked, by definition, to the x-ray absorption properties of a specific material. This work is supported by U.S. DoE/NNSA Grant No. 435 DENA0001835.

Practical method for evaluating the visibility of moire patterns for CRT design

NASA Astrophysics Data System (ADS)

Shiramatsu, Naoki; Tanigawa, Masashi; Iwata, Shuji

1995-04-01

The high resolution CRT displays used for computer monitor and high performance TV often produce a pattern of bright and dark stripes on the screen called a moire pattern. The elimination of the moire is an important consideration in the CRT design. The objective of this study is to provide a practical method for estimating and evaluating a moire pattern considering the visibility by the human vision. On the basis of the mathematical model of a moire generation, precise value of the period and the intensity of a moire are calculated from the actual data of the electron beam profile and the transmittance distribution of apertures of the shadow mask. The visibility of the moire is evaluated by plotting the calculation results on the contrast-period plane, which consists of visible and invisible moire pattern regions based on experimental results of the psychological tests. Not only fundamental design parameters such as a shadow mask pitch and a scanning line pitch but also details of an electron beam profile such as a distortion or an asymmetry can be examined. In addition to the analysis, the image simulation of a moire using the image memory is also available.

Global control of colored moiré pattern in layered optical structures

NASA Astrophysics Data System (ADS)

Li, Kunyang; Zhou, Yangui; Pan, Di; Ma, Xueyan; Ma, Hongqin; Liang, Haowen; Zhou, Jianying

2018-05-01

Accurate description of visual effect of colored moiré pattern caused by layered optical structures consisting of gratings and Fresnel lens is proposed in this work. The colored moiré arising from the periodic and quasi-periodic structures is numerically simulated and experimentally verified. It is found that the visibility of moiré pattern generated by refractive optical elements is related to not only the spatial structures of gratings but also the viewing angles. To effectively control the moiré visibility, two constituting gratings are slightly separated. Such scheme is proved to be effective to globally eliminate moiré pattern for displays containing refractive optical films with quasi-periodic structures.

Patient-specific 3D models created by 3D imaging system or bi-planar imaging coupled with Moiré-Fringe projections: a comparative study of accuracy and reliability on spinal curvatures and vertebral rotation data.

PubMed

Hocquelet, Arnaud; Cornelis, François; Jirot, Anna; Castaings, Laurent; de Sèze, Mathieu; Hauger, Olivier

2016-10-01

The aim of this study is to compare the accuracy and reliability of spinal curvatures and vertebral rotation data based on patient-specific 3D models created by 3D imaging system or by bi-planar imaging coupled with Moiré-Fringe projections. Sixty-two consecutive patients from a single institution were prospectively included. For each patient, frontal and sagittal calibrated low-dose bi-planar X-rays were performed and coupled simultaneously with an optical Moiré back surface-based technology. The 3D reconstructions of spine and pelvis were performed independently by one radiologist and one technician in radiology using two different semi-automatic methods using 3D radio-imaging system (method 1) or bi-planar imaging coupled with Moiré projections (method 2). Both methods were compared using Bland-Altman analysis, and reliability using intraclass correlation coefficient (ICC). ICC showed good to very good agreement. Between the two techniques, the maximum 95 % prediction limits was -4.9° degrees for the measurements of spinal coronal curves and less than 5° for other parameters. Inter-rater reliability was excellent for all parameters across both methods, except for axial rotation with method 2 for which ICC was fair. Method 1 was faster for reconstruction time than method 2 for both readers (13.4 vs. 20.7 min and 10.6 vs. 13.9 min; p = 0.0001). While a lower accuracy was observed for the evaluation of the axial rotation, bi-planar imaging coupled with Moiré-Fringe projections may be an accurate and reliable tool to perform 3D reconstructions of the spine and pelvis.

Rapid Technology Assessment via Unified Deployment of Global Optical and Virtual Diagnostics

NASA Technical Reports Server (NTRS)

Jordan, Jeffrey D.; Watkins, A. Neal; Fleming, Gary A.; Leighty, Bradley D.; Schwartz, Richard J.; Ingram, JoAnne L.; Grinstead, Keith D., Jr.; Oglesby, Donald M.; Tyler, Charles

2003-01-01

This paper discusses recent developments in rapid technology assessment resulting from an active collaboration between researchers at the Air Force Research Laboratory (AFRL) at Wright Patterson Air Force Base (WPAFB) and the NASA Langley Research Center (LaRC). This program targets the unified development and deployment of global measurement technologies coupled with a virtual diagnostic interface to enable the comparative evaluation of experimental and computational results. Continuing efforts focus on the development of seamless data translation methods to enable integration of data sets of disparate file format in a common platform. Results from a successful low-speed wind tunnel test at WPAFB in which global surface pressure distributions were acquired simultaneously with model deformation and geometry measurements are discussed and comparatively evaluated with numerical simulations. Intensity- and lifetime-based pressure-sensitive paint (PSP) and projection moire interferometry (PMI) results are presented within the context of rapid technology assessment to enable simulation-based R&D.

Creep-fatigue interaction at high temperature; Proceedings of the Symposium, 112th ASME Winter Annual Meeting, Atlanta, GA, Dec. 1-6, 1991

NASA Astrophysics Data System (ADS)

Haritos, George K.; Ochoa, O. O.

Various papers on creep-fatigue interaction at high temperature are presented. Individual topics addressed include: analysis of elevated temperature fatigue crack growth mechanisms in Alloy 718, physically based microcrack propagation laws for creep-fatigue-environment interaction, in situ SEM observation of short fatigue crack growth in Waspaloy at 700 C under cyclic and dwell conditions, evolution of creep-fatigue life prediction models, TMF design considerations in turbine airfoils of advanced turbine engines. Also discussed are: high temperature fatigue life prediction computer code based on the total strain version of strainrange partitioning, atomic theory of thermodynamics of internal variables, geometrically nonlinear analysis of interlaminar stresses in unsymmetrically laminated plates subjected to uniform thermal loading, experimental investigation of creep crack tip deformation using moire interferometry. (For individual items see A93-31336 to A93-31344)

Optical Signal Processing: Poisson Image Restoration and Shearing Interferometry

NASA Technical Reports Server (NTRS)

Hong, Yie-Ming

1973-01-01

Optical signal processing can be performed in either digital or analog systems. Digital computers and coherent optical systems are discussed as they are used in optical signal processing. Topics include: image restoration; phase-object visualization; image contrast reversal; optical computation; image multiplexing; and fabrication of spatial filters. Digital optical data processing deals with restoration of images degraded by signal-dependent noise. When the input data of an image restoration system are the numbers of photoelectrons received from various areas of a photosensitive surface, the data are Poisson distributed with mean values proportional to the illuminance of the incoherently radiating object and background light. Optical signal processing using coherent optical systems is also discussed. Following a brief review of the pertinent details of Ronchi's diffraction grating interferometer, moire effect, carrier-frequency photography, and achromatic holography, two new shearing interferometers based on them are presented. Both interferometers can produce variable shear.

Strain measurement in the wavy-ply region of an externally pressurized cross-ply composite ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gascoigne, H.E.; Abdallah, M.G.

1996-07-01

Ply-level strains are determined in the cross-section of an externally pressurized cross-ply (3:1 circumferential to axial fiber ratio) graphite-epoxy ring containing an isolated circumferential wavy region. A special test fixture was used which permitted measuring orthogonal displacement components in the wavy area using moire interferometry as the pressure was increased. Strain components were determined at selected locations in the wavy area up to approximately90% of failure pressure. The study shows: (1) large interlaminar shear strains, which are non-existent in the perfect ring, are present near the wave inflection points; (2) the wavy plies generate increased interlaminar normal compressive strains inmore » both circumferential and axial plies along a radial line coinciding with maximum wave amplitude; and (3) nonlinear strain response begins at approximately 60% of failure pressure.« less

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.

Dirac electrons in Moiré superlattice: From two to three dimensions

NASA Astrophysics Data System (ADS)

Hu, Chen; Michaud-Rioux, Vincent; Kong, Xianghua; Guo, Hong

2017-11-01

Moiré patterns in van der Waals (vdW) heterostructures bring novel physical effects to the materials. We report theoretical investigations of the Moiré pattern formed by graphene (Gr) on hexagonal boron nitride (h BN). For both the two-dimensional (2D) flat-sheet and the freestanding three-dimensional (3D) wavelike film geometries, the behaviors of Dirac electrons are strongly modulated by the local high-symmetry stacking configurations of the Moiré pattern. In the 2D flat sheet, the secondary Dirac cone (SDC) dispersion emerges due to the stacking-selected localization of SDC wave functions, while the original Dirac cone (ODC) gap is suppressed due to an overall effect of ODC wave functions. In the freestanding 3D wavelike Moiré structure, we predict that a specific local stacking in the Moiré superlattice is promoted at the expense of other local stackings, leading to an electronic structure more similar to that of the perfectly matching flat Gr/h BN than that of the flat-sheet 2D Moiré pattern. To capture the overall picture of the Moiré superlattice, supercells containing 12 322 atoms are simulated by first principles.

Reduction of a grid moiré pattern by integrating a carbon-interspaced high precision x-ray grid with a digital radiographic detector.

PubMed

Yoon, Jai-Woong; Park, Young-Guk; Park, Chun-Joo; Kim, Do-Il; Lee, Jin-Ho; Chung, Nag-Kun; Choe, Bo-Young; Suh, Tae-Suk; Lee, Hyoung-Koo

2007-11-01

The stationary grid commonly used with a digital x-ray detector causes a moiré interference pattern due to the inadequate sampling of the grid shadows by the detector pixels. There are limitations with the previous methods used to remove the moiré such as imperfect electromagnetic interference shielding and the loss of image information. A new method is proposed for removing the moiré pattern by integrating a carbon-interspaced high precision x-ray grid with high grid line uniformity with the detector for frequency matching. The grid was aligned to the detector by translating and rotating the x-ray grid with respect to the detector using microcontrolled alignment mechanism. The gap between the grid and the detector surface was adjusted with micrometer precision to precisely match the projected grid line pitch to the detector pixel pitch. Considering the magnification of the grid shadows on the detector plane, the grids were manufactured such that the grid line frequency was slightly higher than the detector sampling frequency. This study examined the factors that affect the moiré pattern, particularly the line frequency and displacement. The frequency of the moiré pattern was found to be sensitive to the angular displacement of the grid with respect to the detector while the horizontal translation alters the phase but not the moiré frequency. The frequency of the moiré pattern also decreased with decreasing difference in frequency between the grid and the detector, and a moiré-free image was produced after complete matching for a given source to detector distance. The image quality factors including the contrast, signal-to-noise ratio and uniformity in the images with and without the moiré pattern were investigated.

A Novel Femtosecond-gated, High-resolution, Frequency-shifted Shearing Interferometry Technique for Probing Pre-plasma Expansion in Ultra-intense Laser Experiments

DTIC Science & Technology

2014-07-17

frequency-shifted shearing interferometry technique for probing pre-plasma expansion in ultra-intense laser experimentsa) Ultra-intense laser -matter...interaction experiments (>1018 W/cm2) with dense targets are highly sensitive to the effect of laser “noise” (in the form of pre-pulses) preceding the...interferometry technique for probing pre- plasma expansion in ultra-intense laser experimentsa) Report Title Ultra-intense laser -matter interaction

High-accuracy contouring using projection moiré

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Lamberti, Luciano; Sciammarella, Federico M.

2005-09-01

Shadow and projection moiré are the oldest forms of moiré to be used in actual technical applications. In spite of this fact and the extensive number of papers that have been published on this topic, the use of shadow moiré as an accurate tool that can compete with alternative devices poses very many problems that go to the very essence of the mathematical models used to obtain contour information from fringe pattern data. In this paper some recent developments on the projection moiré method are presented. Comparisons between the results obtained with the projection method and the results obtained by mechanical devices that operate with contact probes are presented. These results show that the use of projection moiré makes it possible to achieve the same accuracy that current mechanical touch probe devices can provide.

Nondestructive evaluation of turbine blades vibrating in resonant modes

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Ahmadshahi, Mansour A.

1991-12-01

The paper presents the analysis of the strain distribution of turbine blades. The holographic moire technique is used in conjunction with computer analysis of the fringes. The application of computer fringe analysis technique reduces the number of holograms to be recorded to two. Stroboscopic illumination is used to record the patterns. Strains and stresses are computed.

An Externally Dispersed Interferometer for Sensitive Doppler Extrasolar Planet Searches

NASA Astrophysics Data System (ADS)

Ge, Jian; Erskine, David J.; Rushford, Mike

2002-09-01

A new kind of instrument for sensitive Doppler extrasolar planet searches, called an externally dispersed interferometer, is described in this paper. It is a combination of an optical Michelson-type interferometer and an intermediate-resolution grating spectrometer. The interferometer measures Doppler radial velocity (RV) variations of starlight through the phase shifts of moiré fringes, created by multiplication of the interferometer fringes with stellar absorption lines. The intermediate-resolution spectrograph disperses the moiré fringes into thousands of parallel-wavelength channels. This increases the instrument bandwidth and fringe visibility by preventing fringe cross-talk between neighboring spectral lines. This results in a net increase in the signal-to-noise ratio over an interferometer used alone with broadband light. Compared to current echelle spectrometers for extrasolar planet searches, this instrument offers two unique instrument properties: a simple, stable, well-defined sinusoidal instrument response function (point-spread function) and magnification of Doppler motion through moiré fringe techniques. Since instrument noise is chiefly limited by the ability to characterize the instrument response, this new technique provides unprecedented low instrumental noise in an economical compact apparatus, enabling higher precision for Doppler RV measurements. In practice, the moiré magnification can be 5-10 times depending on the interferometer comb angle. This instrument has better sensitivity for smaller Doppler shifts than echelle spectrometers. The instrument can be designed with much lower spectral resolving power without losing Doppler sensitivity and optimized for higher throughput than echelle spectrometers to allow a potential survey for planets around fainter stars than current magnitude limits. Lab-based experiments with a prototype instrument with a spectral resolution of R~20,000 demonstrated ~0.7 m s-1 precision for short-term RV measurements. A fiber-fed version of the prototype with R~5600 was tested with starlight at the Lick 1 m telescope and demonstrated ~7 m s-1 RV precision at 340 Å bandwidth. The increased velocity noise is attributed to the lower spectral resolution, lower fringe visibility, and uncontrolled instrument environment.

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.

A real-time interferometer technique for compressible flow research

NASA Technical Reports Server (NTRS)

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

1984-01-01

Strengths and shortcomings in the application of interferometric techniques to transonic flow fields are examined and an improved method is elaborated. Such applications have demonstrated the value of interferometry in obtaining data for compressible flow research. With holographic techniques, interferometry may be applied in large scale facilities without the use of expensive optics or elaborate vibration isolation equipment. Results obtained using holographic interferometry and other methods demonstrate that reliable qualitative and quantitative data can be acquired. Nevertheless, the conventional method can be difficult to set up and apply, and it cannot produce real-time data. A new interferometry technique is investigated that promises to be easier to apply and can provide real-time information. This single-beam technique has the necessary insensitivity to vibration for large scale wind tunnel operations. Capabilities of the method and preliminary tests on some laboratory scale flow fluids are described.

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)

Color moiré simulations in contact-type 3-D displays.

PubMed

Lee, B-R; Son, J-Y; Chernyshov, O O; Lee, H; Jeong, I-K

2015-06-01

A new method of color moiré fringe simulation in the contact-type 3-D displays is introduced. The method allows simulating color moirés appearing in the displays, which cannot be approximated by conventional cosine approximation of a line grating. The color moirés are mainly introduced by the line width of the boundary lines between the elemental optics in and plate thickness of viewing zone forming optics. This is because the lines are hiding some parts of pixels under the viewing zone forming optics, and the plate thickness induces a virtual contraction of the pixels. The simulated color moiré fringes are closely matched with those appearing at the displays.

Moire-Fringe Images of Twin Boundaries in Chemical Vapor Deposited Diamond

DTIC Science & Technology

1992-07-10

Moire-Fringe Images of Twin Boundaries in Chemical Vapor Deposited Diamond IJ PERSONAL AUITHOR(S) - D. Shechtman. A. Fldman, M.D. Vaudin, and J.L...micrographs of chemical vapor deposited diamond can be interprete as Moire fringes that occur when viewing twin boundaries that are inclined to the electron...Dist J Special TECHNICAL REPORT No. 14 eca MOIRE-FRINGE IMAGES OF TWIN BOUNDARIES IN CHEMICAL VAPOR DEPOSITED DIAMOND D. Shechtman, A. Feldman, M.D

Charge transport through one-dimensional Moiré crystals

PubMed Central

Bonnet, Roméo; Lherbier, Aurélien; Barraud, Clément; Rocca, Maria Luisa Della; Lafarge, Philippe; Charlier, Jean-Christophe

2016-01-01

Moiré superlattices were generated in two-dimensional (2D) van der Waals heterostructures and have revealed intriguing electronic structures. The appearance of mini-Dirac cones within the conduction and valence bands of graphene is one of the most striking among the new quantum features. A Moiré superstructure emerges when at least two periodic sub-structures superimpose. 2D Moiré patterns have been particularly investigated in stacked hexagonal 2D atomic lattices like twisted graphene layers and graphene deposited on hexagonal boron-nitride. In this letter, we report both experimentally and theoretically evidence of superlattices physics in transport properties of one-dimensional (1D) Moiré crystals. Rolling-up few layers of graphene to form a multiwall carbon nanotube adds boundaries conditions that can be translated into interference fringes-like Moiré patterns along the circumference of the cylinder. Such a 1D Moiré crystal exhibits a complex 1D multiple bands structure with clear and robust interband quantum transitions due to the presence of mini-Dirac points and pseudo-gaps. Our devices consist in a very large diameter (>80 nm) multiwall carbon nanotubes of high quality, electrically connected by metallic electrodes acting as charge reservoirs. Conductance measurements reveal the presence of van Hove singularities assigned to 1D Moiré superlattice effect and illustrated by electronic structure calculations. PMID:26786067

Fatigue crack tip deformation and fatigue crack propagation

NASA Technical Reports Server (NTRS)

Kang, T. S.; Liu, H. W.

1972-01-01

The effects of stress ratio, prestress cycling and plate thickness on the fatigue crack propagation rate are studied on 2024-T351 aluminum alloy. Fatigue crack propagation rate increases with the plate thickness and the stress ratio. Prestress cycling below the static yield strength has no noticeable effect on the fatigue crack propagation rate. However, prestress cycling above the static yield strength causes the material to strain harden and increases the fatigue crack propagation rate. Crack tip deformation is used to study the fatigue crack propagation. The crack tip strains and the crack opening displacements were measured from moire fringe patterns. The moire fringe patterns were obtained by a double exposure technique, using a very high density master grille (13,400 lines per inch).

Talbot-Lau x-ray deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments (invited).

PubMed

Valdivia, M P; Stutman, D; Stoeckl, C; Mileham, C; Begishev, I A; Theobald, W; Bromage, J; Regan, S P; Klein, S R; Muñoz-Cordovez, G; Vescovi, M; Valenzuela-Villaseca, V; Veloso, F

2016-11-01

Talbot-Lau X-ray deflectometry (TXD) has been developed as an electron density diagnostic for High Energy Density (HED) plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping were demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moiré pattern formation and grating survival were also observed using a copper x-pinch driven at 400 kA, ∼1 kA/ns. These results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

Talbot-Lau X-ray Deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments

DOE PAGES

Valdivia, M. P.; Stutman, D.; Stoeckl, C.; ...

2016-04-21

Talbot-Lau X-ray Deflectometry has been developed as an electron density diagnostic for High Energy Density plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping was demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moire pattern formation and grating survival was also observed using a copper x-pinch driven at 400 kA, ~1 kA/ns. Lastly, these results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

Simultaneous immersion Mirau interferometry.

PubMed

Lyulko, Oleksandra V; Randers-Pehrson, Gerhard; Brenner, David J

2013-05-01

A novel technique for label-free imaging of live biological cells in aqueous medium that is insensitive to ambient vibrations is presented. This technique is a spin-off from previously developed immersion Mirau interferometry. Both approaches utilize a modified Mirau interferometric attachment for a microscope objective that can be used both in air and in immersion mode, when the device is submerged in cell medium and has its internal space filled with liquid. While immersion Mirau interferometry involves first capturing a series of images, the resulting images are potentially distorted by ambient vibrations. Overcoming these serial-acquisition challenges, simultaneous immersion Mirau interferometry incorporates polarizing elements into the optics to allow simultaneous acquisition of two interferograms. The system design and production are described and images produced with the developed techniques are presented.

Precision optical device of freeform defects inspection

NASA Astrophysics Data System (ADS)

Meguellati, S.

2015-09-01

This method of optical scanning presented in this paper is used for precision measurement deformation in shape or absolute forms in comparison with a reference component form, of optical or mechanical components, on reduced surfaces area that are of the order of some mm2 and more. The principle of the method is to project the image of the source grating to palpate optically surface to be inspected, after reflection; the image of the source grating is printed by the object topography and is then projected onto the plane of reference grating for generate moiré fringe for defects detection. The optical device used allows a significant dimensional surface magnification of up to 1000 times the area inspected for micro-surfaces, which allows easy processing and reaches an exceptional nanometric imprecision of measurements. According to the measurement principle, the sensitivity for displacement measurement using moiré technique depends on the frequency grating, for increase the detection resolution. This measurement technique can be used advantageously to measure the deformations generated by the production process or constraints on functional parts and the influence of these variations on the function. The optical device and optical principle, on which it is based, can be used for automated inspection of industrially produced goods. It can also be used for dimensional control when, for example, to quantify the error as to whether a piece is good or rubbish. It then suffices to compare a figure of moiré fringes with another previously recorded from a piece considered standard; which saves time, money and accuracy. The technique has found various applications in diverse fields, from biomedical to industrial and scientific applications.

Moiré assisted fractional quantum Hall state spectroscopy

DOE PAGES

Wu, Fengcheng; MacDonald, A. H.

2016-12-14

Intra-Landau level excitations in the fractional quantum Hall regime are not accessible via optical absorption measurements. Here we point out that optical probes are enabled by the periodic potentials produced by a moire pattern. Our observation is motivated by the recent observations of fractional quantum Hall incompressible states in moire-patterned graphene on a hexagonal boron nitride substrate, and is theoretically based on f-sum rule considerations supplemented by a perturbative analysis of the influence of the moire potential on many-body states.

School scoliosis screening by Moiré topography - Overview for 33 years in Miyazaki Japan.

PubMed

Kuroki, Hiroshi; Nagai, Takuya; Chosa, Etsuo; Tajima, Naoya

2018-04-05

Since 1981, we have performed school scoliosis screening (SSS) using Moiré topography in Miyazaki, Japan and attained a certain result in detecting scoliosis. However, this screening system was discontinued due to cessation of repair and production of Moiré topographic equipment. The purpose of this study was to make clear both the results and the problems of SSS by Moiré topography on the basis of our past 33 years' experiences. The subjects were 689,293 students (5th grade boys in 200,329, 5th grade girls in 191,919, 8th grade boys in 151,351, and 8th grade girls in 145,694) who were screened by Moiré topography between 1981 and 2013. The number of students received SSS, the positive rate of Moiré topography, the discovery rate of scoliosis greater than 20°, the reference rate to the second screening, and the positive predictive value of Moiré topography to detect scoliosis greater than 20° were investigated. The number of students received SSS achieved a peak in 1992. The positive rate of Moiré topography and the discovery rate of scoliosis were highest in 8th grade girls. The reference rates to the second screening were 49.8% in 5th grade students and 41.4% in 8th grade students. The positive predictive values were 2.1% in 5th grade students and 7.6% in 8th grade students. SSS by Moiré topography seemed to be effective in detecting scoliosis although both the positive predictive value and the reference rate to the second screening were low. Copyright © 2018. Published by Elsevier B.V.

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.…

Stacked Fresnel Zone Plates for High Energy X-rays

NASA Astrophysics Data System (ADS)

Snigireva, Irina; Snigirev, Anatoly; Vaughan, Gavin; Di Michiel, Marco; Kohn, Viktor; Yunkin, Vyacheslav; Grigoriev, Maxim

2007-01-01

A stacking technique was developed in order to increase focusing efficiency of Fresnel zone plates (FZP) at high energies. Two identical Si chips each of which containing 9 FZPs were used for stacking. Alignment of the chips was achieved by on-line observation of the moiré pattern. The formation of moiré patterns was studied theoretically and experimentally at different experimental conditions. To provide the desired stability Si-chips were bonded together with slow solidification speed epoxy glue. A technique of angular alignment in order to compensate a linear displacement in the process of gluing was proposed. Two sets of stacked FZPs were experimentally tested to focus 15 and 50 keV x rays. The gain in the efficiency by factor 2.5 was demonstrated at 15 keV. The focal spot of 1.8 μm vertically and 14 μm horizontally with 35% efficiency was measured at 50 keV. Forecast for the stacking of nanofocusing FZPs was discussed.

Hard X-ray focusing by stacked Fresnel zone plates

NASA Astrophysics Data System (ADS)

Snigireva, Irina; Snigirev, Anatoly; Kohn, Viktor; Yunkin, Vyacheslav; Grigoriev, Maxim; Kuznetsov, Serguei; Vaughan, Gavin; Di Michiel, Marco

2007-09-01

Stacking technique was developed in order to increase focusing efficiency of Fresnel zone plates at high energies. Two identical Si chips each of which containing Fresnel zone plates were used for stacking. Alignment of the chips was achieved by on-line observation of the moiré pattern from the two zone plates. The formation of moiré patterns was studied theoretically and experimentally at different experimental conditions. To provide the desired stability Si-chips with zone plates were bonded together with slow solidification speed epoxy glue. Technique of angular alignment in order to compensate a linear displacement in the process of gluing was proposed. Two sets of stacked FZPs were produced and experimentally tested to focus 15 and 50 keV X-rays. Gain in the efficiency by factor 2.5 was demonstrated at 15 keV. Focal spot of 1.8 μm vertically and 14 μm horizontally with 35% efficiency was measured at 50 keV. Forecast for the stacking of nanofocusing Fresnel zone plates was discussed.

Directed assembly of colloidal particles for micro/nano photonics (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zheng, Yuebing

2017-02-01

Bottom-up fabrication of complex structures with chemically synthesized colloidal particles as building blocks pave an efficient and cost-effective way towards micro/nano photonics with unprecedented functionality and tunability. Novel properties can arise from quantum effects of colloidal particles, as well as inter-particle interactions and spatial arrangement in particle assemblies. Herein, I discuss our recent developments and applications of three types of techniques for directed assembly of colloidal particles: moiré nanosphere lithography (MNSL), bubble-pen lithography (BPL), and optothermal tweezers (OTTs). Specifically, MNSL provides an efficient approach towards creating moiré metasurface with tunable and multiband optical responses from visible to mid-infrared regime. Au moiré metasurfaces have been applied for surface-enhanced infrared spectroscopy, optical capture and patterning of bacteria, and photothermal denaturation of proteins. BPL is developed to pattern a variety of colloidal particles on plasmonic substrates and two-dimensional atomic-layer materials in an arbitrary manner. The laser-directed microbubble captures and immobilizes nanoparticles through coordinated actions of Marangoni convection, surface tension, gas pressure, and substrate adhesion. OTTs are developed to create dynamic nanoparticle assemblies at low optical power. Such nanoparticle assemblies have been used for surface-enhanced Raman spectroscopy for molecular analysis in their native environments.

The Wide-Field Imaging Interferometry Testbed: Enabling Techniques for High Angular Resolution Astronomy

NASA Technical Reports Server (NTRS)

Rinehart, S. A.; Armstrong, T.; Frey, Bradley J.; Jung, J.; Kirk, J.; Leisawitz, David T.; Leviton, Douglas B.; Lyon, R.; Maher, Stephen; Martino, Anthony J.;

Simultaneous immersion Mirau interferometry

PubMed Central

Lyulko, Oleksandra V.; Randers-Pehrson, Gerhard; Brenner, David J.

2013-01-01

A novel technique for label-free imaging of live biological cells in aqueous medium that is insensitive to ambient vibrations is presented. This technique is a spin-off from previously developed immersion Mirau interferometry. Both approaches utilize a modified Mirau interferometric attachment for a microscope objective that can be used both in air and in immersion mode, when the device is submerged in cell medium and has its internal space filled with liquid. While immersion Mirau interferometry involves first capturing a series of images, the resulting images are potentially distorted by ambient vibrations. Overcoming these serial-acquisition challenges, simultaneous immersion Mirau interferometry incorporates polarizing elements into the optics to allow simultaneous acquisition of two interferograms. The system design and production are described and images produced with the developed techniques are presented. PMID:23742552

Probability of the moiré effect in barrier and lenticular autostereoscopic 3D displays.

PubMed

Saveljev, Vladimir; Kim, Sung-Kyu

2015-10-05

The probability of the moiré effect in LCD displays is estimated as a function of angle based on the experimental data; a theoretical function (node spacing) is proposed basing on the distance between nodes. Both functions are close to each other. The connection between the probability of the moiré effect and the Thomae's function is also found. The function proposed in this paper can be used in the minimization of the moiré effect in visual displays, especially in autostereoscopic 3D displays.

Topological Exciton Bands in Moire Heterojunctions.

DOE PAGES

Wu, Fengcheng; Lovorn, Timothy; MacDonald, A. H.

2017-04-05

Moire patterns are common in Van der Waals heterostructures and can be used to apply periodic potentials to elementary excitations. Here, we show that the optical absorption spectrum of transition metal dichalcogenide bilayers is profoundly altered by long period moire patterns that introduce twist-angle dependent satellite excitonic peaks. Topological exciton bands with non-zero Chern numbers that support chiral excitonic edge states can be engineered by combining three ingredients: i) the valley Berry phase induced by electron-hole exchange interactions, ii) the moire potential, and iii) the valley Zeeman field.

Volume moiré tomography based on projection extraction by spatial phase shifting of double crossed gratings

NASA Astrophysics Data System (ADS)

Wang, Jia; Guo, Zhenyan; Song, Yang; Han, Jun

2018-01-01

To realize volume moiré tomography (VMT) for the real three-dimensional (3D) diagnosis of combustion fields, according to 3D filtered back projection (FBP) reconstruction algorithm, the radial derivatives of the projected phase should be measured firstly. In this paper, a simple spatial phase-shifting moiré deflectometry with double cross gratings is presented to measure the radial first-order derivative of the projected phase. Based on scalar diffraction theory, the explicit analytical intensity distributions of moiré patterns on different diffracted orders are derived, and the spatial shifting characteristics are analyzed. The results indicate that the first-order derivatives of the projected phase in two mutually perpendicular directions are involved in moiré patterns, which can be combined to compute the radial first-order derivative. And multiple spatial phase-shifted moiré patterns can be simultaneously obtained; the phase-shifted values are determined by the parameters of the system. A four-step phase-shifting algorithm is proposed for phase extraction, and its accuracy is proved by numerical simulations. Finally, the moiré deflectometry is used to measure the radial first-order derivative of projected phase of a propane flame with plane incident wave, and the 3D temperature distribution is reconstructed.

Holographic analysis as an inspection method for welded thin-wall tubing

NASA Technical Reports Server (NTRS)

Brooks, Lawrence; Mulholland, John; Genin, Joseph; Matthews, Larryl

1990-01-01

The feasibility of using holographic interferometry for locating flaws in welded tubing is explored. Two holographic techniques are considered: traditional holographic interferometry and electronic speckle pattern interferometry. Several flaws including cold laps, discontinuities, and tube misalignments are detected.

Remote online monitoring and measuring system for civil engineering structures

NASA Astrophysics Data System (ADS)

Kujawińska, Malgorzata; Sitnik, Robert; Dymny, Grzegorz; Karaszewski, Maciej; Michoński, Kuba; Krzesłowski, Jakub; Mularczyk, Krzysztof; Bolewicki, Paweł

2009-06-01

In this paper a distributed intelligent system for civil engineering structures on-line measurement, remote monitoring, and data archiving is presented. The system consists of a set of optical, full-field displacement sensors connected to a controlling server. The server conducts measurements according to a list of scheduled tasks and stores the primary data or initial results in a remote centralized database. Simultaneously the server performs checks, ordered by the operator, which may in turn result with an alert or a specific action. The structure of whole system is analyzed along with the discussion on possible fields of application and the ways to provide a relevant security during data transport. Finally, a working implementation consisting of a fringe projection, geometrical moiré, digital image correlation and grating interferometry sensors and Oracle XE database is presented. The results from database utilized for on-line monitoring of a threshold value of strain for an exemplary area of interest at the engineering structure are presented and discussed.

Current developments in optical engineering and diffraction phenomena; Proceedings of the Meeting, San Diego, CA, Aug. 21, 22, 1986

NASA Astrophysics Data System (ADS)

Fischer, Robert E.; Smith, Warren J.; Harvey, James

1986-01-01

Papers dealing with current materials for gradient-index optics, an intelligent data-base system for optical designers; tilted mirror systems; a null-lens design approach for centrally obscured components; the use of the vector aberration theory to optimize an unobscured optical system; multizone bifocal contact lens design; and the concentric meniscus element are presented. Topics discussed include optical manufacturing in the Far East; the optical performance of molded-glass lenses for optical memory applications; through-wafer optical interconnects for multiwafer wafer-scale integrated architecture; optical thin-flim monitoring using optical fibers; aerooptical testing; optical inspection; and a system analysis program for a 32K microcomputer. Consideration is given to various theories, algorithms, and applications of diffraction, a vector formulation of a ray-equivalent method for Gaussian beam propagation; Fourier optical analysis of aberrations in focused laser beams; holography and moire interferometry; and phase-conjugate optical correctors for diffraction-limited applications.

Measurement and Prediction of the Thermomechanical Response of Shape Memory Alloy Hybrid Composite Beams

NASA Technical Reports Server (NTRS)

Davis, Brian; Turner, Travis L.; Seelecke, Stefan

2008-01-01

An experimental and numerical investigation into the static and dynamic responses of shape memory alloy hybrid composite (SMAHC) beams is performed to provide quantitative validation of a recently commercialized numerical analysis/design tool for SMAHC structures. The SMAHC beam specimens consist of a composite matrix with embedded pre-strained SMA actuators, which act against the mechanical boundaries of the structure when thermally activated to adaptively stiffen the structure. Numerical results are produced from the numerical model as implemented into the commercial finite element code ABAQUS. A rigorous experimental investigation is undertaken to acquire high fidelity measurements including infrared thermography and projection moire interferometry for full-field temperature and displacement measurements, respectively. High fidelity numerical results are also obtained from the numerical model and include measured parameters, such as geometric imperfection and thermal load. Excellent agreement is achieved between the predicted and measured results of the static and dynamic thermomechanical response, thereby providing quantitative validation of the numerical tool.

Talbot-Lau x-ray deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments (invited)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valdivia, M. P., E-mail: mpvaldivia@pha.jhu.edu; Stutman, D.; Stoeckl, C.

2016-11-15

Talbot-Lau X-ray deflectometry (TXD) has been developed as an electron density diagnostic for High Energy Density (HED) plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping were demonstrated for 25–29 J, 8–30 ps laser pulses using copper foil targets. Moiré pattern formation and grating survival were also observed using a copper x-pinch driven at 400 kA, ∼1 kA/ns. These results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

Coseismic Displacement Analysis of the 12 November 2017 MW 7.3 Sarpol-E Zahab (iran) Earthquake from SAR Interferometry, Burst Overlap Interferometry and Offset Tracking

NASA Astrophysics Data System (ADS)

Vajedian, Sanaz; Motagh, Mahdi

2018-04-01

Interferometric wide-swath mode of Sentinel-1, which is implemented by Terrain Observation by Progressive Scan (TOPS) technique, is the main mode of SAR data acquisition in this mission. It aims at global monitoring of large areas with enhanced revisit frequency of 6 days at the expense of reduced azimuth resolution, compared to classical ScanSAR mode. TOPS technique is equipped by steering the beam from backward to forward along the heading direction for each burst, in addition to the steering along the range direction, which is the only sweeping direction in standard ScanSAR mode. This leads to difficulty in measuring along-track displacement by applying the conventional method of multi-aperture interferometry (MAI), which exploits a double difference interferometry to estimate azimuth offset. There is a possibility to solve this issue by a technique called "Burst Overlap Interferometry" which focuses on the region of burst overlap. Taking advantage of large squint angle diversity of 1° in burst overlapped area leads to improve the accuracy of ground motion measurement especially in along-track direction. We investigate the advantage of SAR Interferometry (InSAR), burst overlap interferometry and offset tracking to investigate coseismic deformation and coseismic-induced landslide related to 12 November 2017 Mw 7.3 Sarpol-e Zahab earthquake in Iran.

Calibration of misalignment errors in the non-null interferometry based on reverse iteration optimization algorithm

NASA Astrophysics Data System (ADS)

Zhang, Xinmu; Hao, Qun; Hu, Yao; Wang, Shaopu; Ning, Yan; Li, Tengfei; Chen, Shufen

2017-10-01

With no necessity of compensating the whole aberration introduced by the aspheric surfaces, non-null test has the advantage over null test in applicability. However, retrace error, which is brought by the path difference between the rays reflected from the surface under test (SUT) and the incident rays, is introduced into the measurement and makes up of the residual wavefront aberrations (RWAs) along with surface figure error (SFE), misalignment error and other influences. Being difficult to separate from RWAs, the misalignment error may remain after measurement and it is hard to identify whether it is removed or not. It is a primary task to study the removal of misalignment error. A brief demonstration of digital Moiré interferometric technique is presented and a calibration method for misalignment error on the basis of reverse iteration optimization (RIO) algorithm in non-null test method is addressed. The proposed method operates mostly in the virtual system, and requires no accurate adjustment in the real interferometer, which is of significant advantage in reducing the errors brought by repeating complicated manual adjustment, furthermore improving the accuracy of the aspheric surface test. Simulation verification is done in this paper. The calibration accuracy of the position and attitude can achieve at least a magnitude of 10-5 mm and 0.0056×10-6rad, respectively. The simulation demonstrates that the influence of misalignment error can be precisely calculated and removed after calibration.

Optical Strain and Crack-Detection Measurements on a Rotating Disk

NASA Technical Reports Server (NTRS)

Woike, Mark; Abdul-Aziz, Ali; Clem, Michelle; Fralick, Gustave

2013-01-01

The development of techniques for the in-situ measurement and structural health monitoring of the rotating components in gas turbine engines is of major interest to NASA. As part of this on-going effort, several experiments have been undertaken to develop methods for detecting cracks and measuring strain on rotating turbine engine like disks. Previous methods investigated have included the use of blade tip clearance sensors to detect the presence of cracks by monitoring the change in measured blade tip clearance and analyzing the combined disk-rotor system's vibration response. More recently, an experiment utilizing a novel optical Moiré based concept has been conducted on a subscale turbine engine disk to demonstrate a potential strain measurement and crack detection technique. Moiré patterns result from the overlap of two repetitive patterns with slightly different spacing. When this technique is applied to a rotating disk, it has the potential to allow for the detection of very small changes in spacing and radial growth in a rotating disk due to a flaw such as a crack. This investigation was a continuation of previous efforts undertaken in 2011-2012 to validate this optical concept. The initial demonstration attempted on a subscale turbine engine disk was inconclusive due to the minimal radial growth experienced by the disk during operation. For the present experiment a new subscale Aluminum disk was fabricated and improvements were made to the experimental setup to better demonstrate the technique. A circular reference pattern was laser etched onto a subscale engine disk and the disk was operated at speeds up to 12 000 rpm as a means of optically monitoring the Moiré created by the shift in patterns created by the radial growth due the presence of the simulated crack. Testing was first accomplished on a clean defect free disk as a means of acquiring baseline reference data. A notch was then machined in to the disk to simulate a crack and testing was repeated for the purposes of demonstrating the concept. Displacement data was acquired using external blade tip clearance and shaft displacement sensors as a means of confirming the optical data and for validating other sensor based crack detection techniques.

Optical Strain and Crack-Detection Measurements on a Rotating Disk

NASA Technical Reports Server (NTRS)

Woike, Mark; Abdul-Aziz, Ali; Clem, Michelle M.; Fralick, Gustave

2013-01-01

The development of techniques for the in-situ measurement and structural health monitoring of the rotating components in gas turbine engines is of major interest to NASA. As part of this on-going effort, several experiments have been undertaken to develop methods for detecting cracks and measuring strain on rotating turbine engine like disks. Previous methods investigated have included the use of blade tip clearance sensors to detect the presence of cracks by monitoring the change in measured blade tip clearance and analyzing the combined disk-rotor system's vibration response. More recently, an experiment utilizing a novel optical Moiré based concept has been conducted on a subscale turbine engine disk to demonstrate a potential strain measurement and crack detection technique. Moiré patterns result from the overlap of two repetitive patterns with slightly different spacing. When this technique is applied to a rotating disk, it has the potential to allow for the detection of very small changes in spacing and radial growth in a rotating disk due to a flaw such as a crack. This investigation was a continuation of previous efforts undertaken in 2011 to 2012 to validate this optical concept. The initial demonstration attempted on a subscale turbine engine disk was inconclusive due to the minimal radial growth experienced by the disk during operation. For the present experiment a new subscale Aluminum disk was fabricated and improvements were made to the experimental setup to better demonstrate the technique. A circular reference pattern was laser etched onto a subscale engine disk and the disk was operated at speeds up to 12 000 rpm as a means of optically monitoring the Moiré created by the shift in patterns created by the radial growth due the presence of the simulated crack. Testing was first accomplished on a clean defect free disk as a means of acquiring baseline reference data. A notch was then machined in to the disk to simulate a crack and testing was repeated for the purposes of demonstrating the concept. Displacement data was acquired using external blade tip clearance and shaft displacement sensors as a means of confirming the optical data and for validating other sensor based crack detection techniques.

Spectral interferometry for morphological imaging in in vitro fertilization (IVF) (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zhu, Yizheng; Li, Chengshuai

2016-03-01

Morphological assessment of spermatozoa is of critical importance for in vitro fertilization (IVF), especially intracytoplasmic sperm injection (ICSI)-based IVF. In ICSI, a single sperm cell is selected and injected into an egg to achieve fertilization. The quality of the sperm cell is found to be highly correlated to IVF success. Sperm morphology, such as shape, head birefringence and motility, among others, are typically evaluated under a microscope. Current observation relies on conventional techniques such as differential interference contrast microscopy and polarized light microscopy. Their qualitative nature, however, limits the ability to provide accurate quantitative analysis. Here, we demonstrate quantitative morphological measurement of sperm cells using two types of spectral interferometric techniques, namely spectral modulation interferometry and spectral multiplexing interferometry. Both are based on spectral-domain low coherence interferometry, which is known for its exquisite phase determination ability. While spectral modulation interferometry encodes sample phase in a single spectrum, spectral multiplexing interferometry does so for sample birefringence. Therefore they are capable of highly sensitive phase and birefringence imaging. These features suit well in the imaging of live sperm cells, which are small, dynamic objects with only low to moderate levels of phase and birefringence contrast. We will introduce the operation of both techniques and demonstrate their application to measuring the phase and birefringence morphology of sperm cells.

Digital Holographic Interferometry for Airborne Particle Characterization

DTIC Science & Technology

2015-03-19

Interferometry and polarimetry for aerosol particle characterization, Bioaerosols: Characterization and Environmental Impact, Austin, TX (2014) [organizer...and conference chair]. 6. Invited talk: Holographic Interferometry and polarimetry for aerosol particle characterization, Optical...Stokes parameters, NATO Advanced Science Institute on Special Detection Technique ( Polarimetry ) and Remote Sensing, Kyiv, Ukraine (2010). (c

Accessing High Spatial Resolution in Astronomy Using Interference Methods

ERIC Educational Resources Information Center

Carbonel, Cyril; Grasset, Sébastien; Maysonnave, Jean

2018-01-01

In astronomy, methods such as direct imaging or interferometry-based techniques (Michelson stellar interferometry for example) are used for observations. A particular advantage of interferometry is that it permits greater spatial resolution compared to direct imaging with a single telescope, which is limited by diffraction owing to the aperture of…

Optical Biosensing: Kinetics of Protein A-IGG Binding Using Biolayer Interferometry

ERIC Educational Resources Information Center

Wilson, Jo Leanna; Scott, Israel M.; McMurry, Jonathan L.

2010-01-01

An undergraduate biochemistry laboratory experiment has been developed using biolayer interferometry (BLI), an optical biosensing technique similar to surface plasmon resonance (SPR), in which students obtain and analyze kinetic data for a protein-protein interaction. Optical biosensing is a technique of choice to determine kinetic and affinity…

White-Light Optical Information Processing and Holography.

DTIC Science & Technology

1985-07-29

this technique is the processing system does not require to carry its own light source. It is very suitable for spaceborne and satellite application. We...developed a technique of generating a spatialtrequency color coded speech spectrogram with a white-light optical system . This system not only offers a low...that the annoying moire fringes can be eliminated. In short, we have once again demonstrated the versatility of the white-light progress system ; a

Quantitative measurement of thin phase objects: comparison of speckle deflectometry and defocus-variant lateral shear interferometry.

PubMed

Sjodahl, Mikael; Amer, Eynas

2018-05-10

The two techniques of lateral shear interferometry and speckle deflectometry are analyzed in a common optical system for their ability to measure phase gradient fields of a thin phase object. The optical system is designed to introduce a shear in the frequency domain of a telecentric imaging system that gives a sensitivity of both techniques in proportion to the defocus introduced. In this implementation, both techniques successfully measure the horizontal component of the phase gradient field. The response of both techniques scales linearly with the defocus distance, and the precision is comparative, with a random error in the order of a few rad/mm. It is further concluded that the precision of the two techniques relates to the transverse speckle size in opposite ways. While a large spatial coherence width, and correspondingly a large lateral speckle size, makes lateral shear interferometry less susceptible to defocus, a large lateral speckle size is detrimental for speckle correlation. The susceptibility for the magnitude of the defocus is larger for the lateral shear interferometry technique as compared to the speckle deflectometry technique. The two techniques provide the same type of information; however, there are a few fundamental differences. Lateral shear interferometry relies on a special hardware configuration in which the shear angle is intrinsically integrated into the system. The design of a system sensitive to both in-plane phase gradient components requires a more complex configuration and is not considered in this paper. Speckle deflectometry, on the other hand, requires no special hardware, and both components of the phase gradient field are given directly from the measured speckle deformation field.

Détection homodyne pour mémoires holographiques à stockage bit à bit

NASA Astrophysics Data System (ADS)

Maire, G.; Pauliat, G.; Roosen, G.

2006-10-01

Les mémoires holographiques à stockage bit à bit sont une alternative intéressante à l'approche holographique conventionnelle par pages de données du fait de leur architecture optique simplifiée. Nous proposons et validons ici une procédure de lecture adaptée à de telles mémoires et basée sur une détection homodyne de l'amplitude diffractée par les hologrammes. Ceci permet d'augmenter la quantité de signal utile détecté et s'avère donc prometteur pour accroître le taux de transfert de données de ces mémoires.

Comparison of immersion ultrasound, partial coherence interferometry, and low coherence reflectometry for ocular biometry in cataract patients.

PubMed

Montés-Micó, Robert; Carones, Francesco; Buttacchio, Antonietta; Ferrer-Blasco, Teresa; Madrid-Costa, David

2011-09-01

To compare ocular biometry parameters measured with immersion ultrasound, partial coherence interferometry, and low coherence reflectometry in cataract patients. Measurements of axial length and anterior chamber depth were analyzed and compared using immersion ultrasound, partial coherence interferometry, and low coherence reflectometry. Keratometry (K), flattest axis, and white-to-white measurements were compared between partial coherence interferometry and low coherence reflectometry. Seventy-eight cataract (LOCS II range: 1 to 3) eyes of 45 patients aged between 42 and 90 years were evaluated. A subanalysis as a function of cataract degree was done for axial length and anterior chamber depth between techniques. No statistically significant differences were noted for the study cohort or within each cataract degree among the three techniques for axial length and anterior chamber depth (P>.05, ANOVA test). Measurements between techniques were highly correlated for axial length (R=0.99) and anterior chamber depth (R=0.90 to 0.96) for all methods. Keratometry, flattest axis, and white-to-white measurements were comparable (paired t test, P>.1) and correlated well between partial coherence interferometry and low coherence reflectometry (K1 [R=0.95), K2 [R=0.97], flattest axis [R=0.95], and white-to-white [R=0.92]). Immersion ultrasound, partial coherence interferometry, and low coherence reflectometry provided comparable ocular biometry measurements in cataractous eyes. Copyright 2011, SLACK Incorporated.

Electronic-projecting Moire method applying CBR-technology

NASA Astrophysics Data System (ADS)

Kuzyakov, O. N.; Lapteva, U. V.; Andreeva, M. A.

2018-01-01

Electronic-projecting method based on Moire effect for examining surface topology is suggested. Conditions of forming Moire fringes and their parameters’ dependence on reference parameters of object and virtual grids are analyzed. Control system structure and decision-making subsystem are elaborated. Subsystem execution includes CBR-technology, based on applying case base. The approach related to analysing and forming decision for each separate local area with consequent formation of common topology map is applied.

An Experimental Study of Large Compressive Loads Upon Residual Strain Fields and the Interaction Between Surface Strain Fields Created by Coldworking Fastener Holes.

DTIC Science & Technology

1981-02-01

Strains" (J. of Basic Eng., Vol. 82, Series D, June 1960), pp, 426-434. 10. Morse, S., A.J. Durelli, and C.A. Sciammarella , "Geo- metry of Moire...grid Method, a Practical Moire Stress-analysis Tool" (Exp. Mech., Vol. 7, July 1967), pp. 19A-22A. 20. Sciammarella , C., "Moire-fringe Multiplication

A moiré deflectometer for antimatter

PubMed Central

Aghion, S.; Ahlén, O.; Amsler, C.; Ariga, A.; Ariga, T.; Belov, A. S.; Berggren, K.; Bonomi, G.; Bräunig, P.; Bremer, J.; Brusa, R. S.; Cabaret, L.; Canali, C.; Caravita, R.; Castelli, F.; Cerchiari, G.; Cialdi, S.; Comparat, D.; Consolati, G.; Derking, H.; Di Domizio, S.; Di Noto, L.; Doser, M.; Dudarev, A.; Ereditato, A.; Ferragut, R.; Fontana, A.; Genova, P.; Giammarchi, M.; Gligorova, A.; Gninenko, S. N.; Haider, S.; Huse, T.; Jordan, E.; Jørgensen, L. V.; Kaltenbacher, T.; Kawada, J.; Kellerbauer, A.; Kimura, M.; Knecht, A.; Krasnický, D.; Lagomarsino, V.; Lehner, S.; Magnani, A.; Malbrunot, C.; Mariazzi, S.; Matveev, V. A.; Moia, F.; Nebbia, G.; Nédélec, P.; Oberthaler, M. K.; Pacifico, N.; Petràček, V.; Pistillo, C.; Prelz, F.; Prevedelli, M.; Regenfus, C.; Riccardi, C.; Røhne, O.; Rotondi, A.; Sandaker, H.; Scampoli, P.; Storey, J.; Vasquez, M.A. Subieta; Špaček, M.; Testera, G.; Vaccarone, R.; Widmann, E.; Zavatarelli, S.; Zmeskal, J.

2014-01-01

The precise measurement of forces is one way to obtain deep insight into the fundamental interactions present in nature. In the context of neutral antimatter, the gravitational interaction is of high interest, potentially revealing new forces that violate the weak equivalence principle. Here we report on a successful extension of a tool from atom optics—the moiré deflectometer—for a measurement of the acceleration of slow antiprotons. The setup consists of two identical transmission gratings and a spatially resolving emulsion detector for antiproton annihilations. Absolute referencing of the observed antimatter pattern with a photon pattern experiencing no deflection allows the direct inference of forces present. The concept is also straightforwardly applicable to antihydrogen measurements as pursued by the AEgIS collaboration. The combination of these very different techniques from high energy and atomic physics opens a very promising route to the direct detection of the gravitational acceleration of neutral antimatter. PMID:25066810

A moiré deflectometer for antimatter.

PubMed

Aghion, S; Ahlén, O; Amsler, C; Ariga, A; Ariga, T; Belov, A S; Berggren, K; Bonomi, G; Bräunig, P; Bremer, J; Brusa, R S; Cabaret, L; Canali, C; Caravita, R; Castelli, F; Cerchiari, G; Cialdi, S; Comparat, D; Consolati, G; Derking, H; Di Domizio, S; Di Noto, L; Doser, M; Dudarev, A; Ereditato, A; Ferragut, R; Fontana, A; Genova, P; Giammarchi, M; Gligorova, A; Gninenko, S N; Haider, S; Huse, T; Jordan, E; Jørgensen, L V; Kaltenbacher, T; Kawada, J; Kellerbauer, A; Kimura, M; Knecht, A; Krasnický, D; Lagomarsino, V; Lehner, S; Magnani, A; Malbrunot, C; Mariazzi, S; Matveev, V A; Moia, F; Nebbia, G; Nédélec, P; Oberthaler, M K; Pacifico, N; Petràček, V; Pistillo, C; Prelz, F; Prevedelli, M; Regenfus, C; Riccardi, C; Røhne, O; Rotondi, A; Sandaker, H; Scampoli, P; Storey, J; Vasquez, M A Subieta; Špaček, M; Testera, G; Vaccarone, R; Widmann, E; Zavatarelli, S; Zmeskal, J

2014-07-28

The precise measurement of forces is one way to obtain deep insight into the fundamental interactions present in nature. In the context of neutral antimatter, the gravitational interaction is of high interest, potentially revealing new forces that violate the weak equivalence principle. Here we report on a successful extension of a tool from atom optics--the moiré deflectometer--for a measurement of the acceleration of slow antiprotons. The setup consists of two identical transmission gratings and a spatially resolving emulsion detector for antiproton annihilations. Absolute referencing of the observed antimatter pattern with a photon pattern experiencing no deflection allows the direct inference of forces present. The concept is also straightforwardly applicable to antihydrogen measurements as pursued by the AEgIS collaboration. The combination of these very different techniques from high energy and atomic physics opens a very promising route to the direct detection of the gravitational acceleration of neutral antimatter.

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.

Application of deconvolution interferometry with both Hi-net and KiK-net data

NASA Astrophysics Data System (ADS)

Nakata, N.

2013-12-01

Application of deconvolution interferometry to wavefields observed by KiK-net, a strong-motion recording network in Japan, is useful for estimating wave velocities and S-wave splitting in the near surface. Using this technique, for example, Nakata and Snieder (2011, 2012) found changed in velocities caused by Tohoku-Oki earthquake in Japan. At the location of the borehole accelerometer of each KiK-net station, a velocity sensor is also installed as a part of a high-sensitivity seismograph network (Hi-net). I present a technique that uses both Hi-net and KiK-net records for computing deconvolution interferometry. The deconvolved waveform obtained from the combination of Hi-net and KiK-net data is similar to the waveform computed from KiK-net data only, which indicates that one can use Hi-net wavefields for deconvolution interferometry. Because Hi-net records have a high signal-to-noise ratio (S/N) and high dynamic resolution, the S/N and the quality of amplitude and phase of deconvolved waveforms can be improved with Hi-net data. These advantages are especially important for short-time moving-window seismic interferometry and deconvolution interferometry using later coda waves.

Cell force mapping using a double-sided micropillar array based on the moiré fringe method

NASA Astrophysics Data System (ADS)

Zhang, F.; Anderson, S.; Zheng, X.; Roberts, E.; Qiu, Y.; Liao, R.; Zhang, X.

2014-07-01

The mapping of traction forces is crucial to understanding the means by which cells regulate their behavior and physiological function to adapt to and communicate with their local microenvironment. To this end, polymeric micropillar arrays have been used for measuring cell traction force. However, the small scale of the micropillar deflections induced by cell traction forces results in highly inefficient force analyses using conventional optical approaches; in many cases, cell forces may be below the limits of detection achieved using conventional microscopy. To address these limitations, the moiré phenomenon has been leveraged as a visualization tool for cell force mapping due to its inherent magnification effect and capacity for whole-field force measurements. This Letter reports an optomechanical cell force sensor, namely, a double-sided micropillar array (DMPA) made of poly(dimethylsiloxane), on which one side is employed to support cultured living cells while the opposing side serves as a reference pattern for generating moiré patterns. The distance between the two sides, which is a crucial parameter influencing moiré pattern contrast, is predetermined during fabrication using theoretical calculations based on the Talbot effect that aim to optimize contrast. Herein, double-sided micropillar arrays were validated by mapping mouse embryo fibroblast contraction forces and the resulting force maps compared to conventional microscopy image analyses as the reference standard. The DMPA-based approach precludes the requirement for aligning two independent periodic substrates, improves moiré contrast, and enables efficient moiré pattern generation. Furthermore, the double-sided structure readily allows for the integration of moiré-based cell force mapping into microfabricated cell culture environments or lab-on-a-chip devices.

Numerical evaluation of moiré pattern in touch sensor module with electrode mesh structure in oblique view

NASA Astrophysics Data System (ADS)

Pournoury, M.; Zamiri, A.; Kim, T. Y.; Yurlov, V.; Oh, K.

2016-03-01

Capacitive touch sensor screen with the metal materials has recently become qualified for substitution of ITO; however several obstacles still have to be solved. One of the most important issues is moiré phenomenon. The visibility problem of the metal-mesh, in touch sensor module (TSM) is numerically considered in this paper. Based on human eye contract sensitivity function (CSF), moiré pattern of TSM electrode mesh structure is simulated with MATLAB software for 8 inch screen display in oblique view. Standard deviation of the generated moiré by the superposition of electrode mesh and screen image is calculated to find the optimal parameters which provide the minimum moiré visibility. To create the screen pixel array and mesh electrode, rectangular function is used. The filtered image, in frequency domain, is obtained by multiplication of Fourier transform of the finite mesh pattern (product of screen pixel and mesh electrode) with the calculated CSF function for three different observer distances (L=200, 300 and 400 mm). It is observed that the discrepancy between analytical and numerical results is less than 0.6% for 400 mm viewer distance. Moreover, in the case of oblique view due to considering the thickness of the finite film between mesh electrodes and screen, different points of minimum standard deviation of moiré pattern are predicted compared to normal view.

Developing Wide-Field Spatio-Spectral Interferometry for Far-Infrared Space Applications

NASA Technical Reports Server (NTRS)

Leisawitz, David; Bolcar, Matthew R.; Lyon, Richard G.; Maher, Stephen F.; Memarsadeghi, Nargess; Rinehart, Stephen A.; Sinukoff, Evan J.

2012-01-01

Interferometry is an affordable way to bring the benefits of high resolution to space far-IR astrophysics. We summarize an ongoing effort to develop and learn the practical limitations of an interferometric technique that will enable the acquisition of high-resolution far-IR integral field spectroscopic data with a single instrument in a future space-based interferometer. This technique was central to the Space Infrared Interferometric Telescope (SPIRIT) and Submillimeter Probe of the Evolution of Cosmic Structure (SPECS) space mission design concepts, and it will first be used on the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII). Our experimental approach combines data from a laboratory optical interferometer (the Wide-field Imaging Interferometry Testbed, WIIT), computational optical system modeling, and spatio-spectral synthesis algorithm development. We summarize recent experimental results and future plans.

Far-field interference of a neutron white beam and the applications to noninvasive phase-contrast imaging

NASA Astrophysics Data System (ADS)

Pushin, D. A.; Sarenac, D.; Hussey, D. S.; Miao, H.; Arif, M.; Cory, D. G.; Huber, M. G.; Jacobson, D. L.; LaManna, J. M.; Parker, J. D.; Shinohara, T.; Ueno, W.; Wen, H.

2017-04-01

The phenomenon of interference plays a crucial role in the field of precision measurement science. Wave-particle duality has expanded the well-known interference effects of electromagnetic waves to massive particles. The majority of the wave-particle interference experiments require a near monochromatic beam which limits its applications due to the resulting low intensity. Here we demonstrate white beam interference in the far-field regime using a two-phase-grating neutron interferometer and its application to phase-contrast imaging. The functionality of this interferometer is based on the universal moiré effect that allows us to improve upon the standard Lau setup. Interference fringes were observed with monochromatic and polychromatic neutron beams for both continuous and pulsed beams. Far-field neutron interferometry allows for the full utilization of intense neutron sources for precision measurements of gradient fields. It also overcomes the alignment, stability, and fabrication challenges associated with the more familiar perfect-crystal neutron interferometer, as well as avoids the loss of intensity due to the absorption analyzer grating requirement in Talbot-Lau interferometer.

Elastic-plastic deformation of a metal-matrix composite coupon with a center slot

NASA Technical Reports Server (NTRS)

Post, D.; Czarnek, R.; Joh, D.; Jo, J.; Guo, Y.

1985-01-01

A comprehensive experimental analysis of deformations of the surface of a metal-matrix specimen is reported. The specimen is a 6-ply 0 + or - 45 sub s boron-aluminum tensile coupon with a central slot. Moire interferometry is used for high-sensitivity whole-field measurements of in-plane displacements. Normal and shear strains are calculated from displacement gradients. Displacement fields are analyzed at various load levels from 15% to 95% of the failure load. Deformations of the boron fibers could be distinguished from those of the matrix. Highly localized plastic slip zones occur tangent to the ends of the slot. Shear strains and concurrent transverse compressive strains in the slip zones reach approximately 10% and 1%, respectively. Upon unloading, elastic recovery in surrounding regions causes a reverse plastic shear strain in the slip zone of about 4%. Longitudinal normal strains on the unslotted ligament peak at the slot boundary at about 1% strain. The strain concentration factor at the end of the slot decreases with load level and the advance of plasticity.

Experimental and analytical characterization of triaxially braided textile composites

NASA Technical Reports Server (NTRS)

Masters, John E.; Fedro, Mark J.; Ifju, Peter G.

1993-01-01

There were two components, experimental and analytical, to this investigation of triaxially braided textile composite materials. The experimental portion of the study centered on measuring the materials' longitudinal and transverse tensile moduli, Poisson's ratio, and strengths. The identification of the damage mechanisms exhibited by these materials was also a prime objective of the experimental investigation. The analytical portion of the investigation utilized the Textile Composites Analysis (TECA) model to predict modulus and strength. The analytical and experimental results were compared to assess the effectiveness of the analysis. The figures contained in this paper reflect the presentation made at the conference. They may be divided into four sections: a definition of the material system tested; followed by a series of figures summarizing the experimental results (these figures contain results of a Moire interferometry study of the strain distribution in the material, examples and descriptions of the types of damage encountered in these materials, and a summary of the measured properties); a description of the TECA model follows the experimental results (this includes a series of predicted results and a comparison with measured values); and finally, a brief summary completes the paper.

Surface Curvatures Computation from Equidistance Contours

NASA Astrophysics Data System (ADS)

Tanaka, Hiromi T.; Kling, Olivier; Lee, Daniel T. L.

1990-03-01

The subject of our research is on the 3D shape representation problem for a special class of range image, one where the natural mode of the acquired range data is in the form of equidistance contours, as exemplified by a moire interferometry range system. In this paper we present a novel surface curvature computation scheme that directly computes the surface curvatures (the principal curvatures, Gaussian curvature and mean curvature) from the equidistance contours without any explicit computations or implicit estimates of partial derivatives. We show how the special nature of the equidistance contours, specifically, the dense information of the surface curves in the 2D contour plane, turns into an advantage for the computation of the surface curvatures. The approach is based on using simple geometric construction to obtain the normal sections and the normal curvatures. This method is general and can be extended to any dense range image data. We show in details how this computation is formulated and give an analysis on the error bounds of the computation steps showing that the method is stable. Computation results on real equidistance range contours are also shown.

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

PubMed Central

Fu, Yu; Pedrini, Giancarlo

2014-01-01

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

The Wide-Field Imaging Interferometry Testbed (WIIT): Recent Progress and Results

NASA Technical Reports Server (NTRS)

Rinehart, Stephen A.; Frey, Bradley J.; Leisawitz, David T.; Lyon, Richard G.; Maher, Stephen F.; Martino, Anthony J.

2008-01-01

Continued research with the Wide-Field Imaging Interferometry Testbed (WIIT) has achieved several important milestones. We have moved WIIT into the Advanced Interferometry and Metrology (AIM) Laboratory at Goddard, and have characterized the testbed in this well-controlled environment. The system is now completely automated and we are in the process of acquiring large data sets for analysis. In this paper, we discuss these new developments and outline our future research directions. The WIIT testbed, combined with new data analysis techniques and algorithms, provides a demonstration of the technique of wide-field interferometric imaging, a powerful tool for future space-borne interferometers.

Amplitude and intensity spatial interferometry; Proceedings of the Meeting, Tucson, AZ, Feb. 14-16, 1990

NASA Technical Reports Server (NTRS)

Breckinridge, Jim B. (Editor)

1990-01-01

Attention is given to such topics as ground interferometers, space interferometers, speckle-based and interferometry-based astronomical observations, adaptive and atmospheric optics, speckle techniques, and instrumentation. Particular papers are presented concerning recent progress on the IR Michelson array; the IOTA interferometer project; a space interferometer concept for the detection of extrasolar earth-like planets; IR speckle imaging at Palomar; optical diameters of stars measured with the Mt. Wilson Mark III interferometer; the IR array camera for interferometry with the cophased Multiple Mirror Telescope; optimization techniques appliesd to the bispectrum of one-dimensional IR astronomical speckle data; and adaptive optical iamging for extended objects.

A three-image algorithm for hard x-ray grating interferometry.

PubMed

Pelliccia, Daniele; Rigon, Luigi; Arfelli, Fulvia; Menk, Ralf-Hendrik; Bukreeva, Inna; Cedola, Alessia

2013-08-12

A three-image method to extract absorption, refraction and scattering information for hard x-ray grating interferometry is presented. The method comprises a post-processing approach alternative to the conventional phase stepping procedure and is inspired by a similar three-image technique developed for analyzer-based x-ray imaging. Results obtained with this algorithm are quantitatively comparable with phase-stepping. This method can be further extended to samples with negligible scattering, where only two images are needed to separate absorption and refraction signal. Thanks to the limited number of images required, this technique is a viable route to bio-compatible imaging with x-ray grating interferometer. In addition our method elucidates and strengthens the formal and practical analogies between grating interferometry and the (non-interferometric) diffraction enhanced imaging technique.

Diffraction gratings used as identifying markers

DOEpatents

Deason, Vance A.; Ward, Michael B.

1991-01-01

A finely detailed defraction grating is applied to an object as an identifier or tag which is unambiguous, difficult to duplicate, or remove and transfer to another item, and can be read and compared with prior readings with relative ease. The exact pattern of the defraction grating is mapped by diffraction moire techniques and recorded for comparison with future readings of the same grating.

Incommensurate growth of Co thin film on close-packed Ag(111) surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barman, Sukanta, E-mail: sukanta.ac@gmail.com; Menon, Krishna Kumar S. R., E-mail: krishna.menon@saha.ac.in

2016-05-06

Growth of ultrathin Co layers on close-packed Ag(111)were investigated by means of Low Energy Electron Diffraction (LEED), X-ray Photoelectron Spectroscopy (XPS) and Angle-resolved Photoemission Spectroscopy(ARPES) techniques. The close-packed hexagonal face of Co(0001), exhibits a lattice misfit about 13% with Ag(111) surface which manipulates the growth to be incommensurate up to a certain thickness. The strain field causes aperiodic height undulation in the sub-angstrom regime of the film which was confirmed by p(1 × 1) LEED pattern along with a 6-fold moiré reconstruction pattern in the lower film thickness (up to ∼2ML). The evolution of the LEED pattern was studied withmore » increasing film coverage. Lattice strain was measured with respect to the relative positions of these double spots as a functionof film thickness. Almost a constant strain (∼13%) in the full range of film thickness explains the moiré pattern formation in order to stabilize the incommensurate growth. For higher film coverages, an epitaxial well-ordered commensurate growth was observed. Core level and valance band electronic structures of these films were studied by XPS and ARPES techniques.« less

High speed digital holographic interferometry for hypersonic flow visualization

NASA Astrophysics Data System (ADS)

Hegde, G. M.; Jagdeesh, G.; Reddy, K. P. J.

2013-06-01

Optical imaging techniques have played a major role in understanding the flow dynamics of varieties of fluid flows, particularly in the study of hypersonic flows. Schlieren and shadowgraph techniques have been the flow diagnostic tools for the investigation of compressible flows since more than a century. However these techniques provide only the qualitative information about the flow field. Other optical techniques such as holographic interferometry and laser induced fluorescence (LIF) have been used extensively for extracting quantitative information about the high speed flows. In this paper we present the application of digital holographic interferometry (DHI) technique integrated with short duration hypersonic shock tunnel facility having 1 ms test time, for quantitative flow visualization. Dynamics of the flow fields in hypersonic/supersonic speeds around different test models is visualized with DHI using a high-speed digital camera (0.2 million fps). These visualization results are compared with schlieren visualization and CFD simulation results. Fringe analysis is carried out to estimate the density of the flow field.

Computer assisted holographic moire contouring

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.

2000-01-01

Theoretical analyses and experimental results on holographic moire contouring on diffusely reflecting objects are presented. The sensitivity and limitations of the method are discussed. Particular emphasis is put on computer-assisted data retrieval, processing, and recording.

Fringe periods of color moirés in contact-type 3-D displays.

PubMed

Lee, Hyoung; Kim, Sung-Kyu; Sohn, Kwanghoon; Son, Jung-Young; Chernyshov, Oleksii O

2016-06-27

A mathematical formula of calculating the fringe periods of the color moirés appearing at the contact-type 3-D displays is derived. It is typical that the color moirés are chirped and the period of the line pattern in viewing zone forming optics is more than two times of that of the pixel pattern in the display panel. These make impossible to calculate the fringe periods of the color moirés with the conventional beat frequency formula. The derived formula work very well for any combination of two line patterns having either a same line period or different line periods. This is experimentally proved. Furthermore, it is also shown that the fringe period can be expressed in terms of the viewing distance and focal length of the viewing zone forming optics.

An Evaluation of the Iosipescu Specimen for Composite Materials Shear Property Measurement. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Ho, Henjen

1991-01-01

A detailed evaluation of the suitability of the Iosipescu specimen tested in the modified Wyoming fixture is presented. An experimental investigation using conventional strain gage instrumentation and moire interferometry is performed. A finite element analysis of the Iosipescu shear test for unidirectional and cross-ply composites is used to assess the uniformity of the shear stress field in the vicinity of the notch, and demonstrate the effect of the nonuniform stress field upon the strain gage measurements used for the determination of composite shear moduli. From the test results for graphite-epoxy laminates, it is shown that the proximity of the load introduction point to the test section greatly influences the individual gage readings for certain fiber orientations but the effect upon shear modulus measurement is relatively unimportant. A numerical study of the load contact effect shows the sensitivity of some fiber configurations to the specimen/fixture contact mechanism and may account for the variations in the measured shear moduli. A comparison of the strain gage readings from one surface of a specimen with corresponding data from moire interferometry on the opposite face documented an extreme sensitivity of some fiber orientations to eccentric loading which induced twisting and yielded spurious shear stress-strain curves. In the numerical analysis, it is shown that the Iosipescu specimens for different fiber orientations have to be modeled differently in order to closely approximate the true loading conditions. Correction factors are needed to allow for the nonuniformity of the strain field and the use of the average shear stress in the shear modulus evaluation. The correction factors, which are determined for the region occupied by the strain gage rosette, are found to be dependent upon the material orthotropic ratio and the finite element models. Based upon the experimental and numerical results, recommendations for improving the reliability and accuracy of the shear modulus values are made, and the implications for shear strength measurement discussed. Further application of the Iosipescu shear test to woven fabric composites is presented. The limitations of the traditional strain gage instrumentation on the satin weave and high tow plain weave fabrics is discussed. Test results of a epoxy based aluminum particulate composite is also presented. A modification of the Iosipescu specimen is proposed and investigated experimentally and numerically. It is shown that the proposed new specimen design provides a more uniform shear stress field in the test section and greatly reduces the normal and shear stress concentrations in the vicinity of the notches. While the fabrication and the material cost of the proposed specimen is tremendously reduced, it is shown the accuracy of the shear modulus measurement is not sacrificed.

Multi-object investigation using two-wavelength phase-shift interferometry guided by an optical frequency comb

NASA Astrophysics Data System (ADS)

Ibrahim, Dahi Ghareab Abdelsalam; Yasui, Takeshi

2018-04-01

Two-wavelength phase-shift interferometry guided by optical frequency combs is presented. We demonstrate the operation of the setup with a large step sample simultaneously with a resolution test target with a negative pattern. The technique can investigate multi-objects simultaneously with high precision. Using this technique, several important applications in metrology that require high speed and precision are demonstrated.

A Possible Future for Space-Based Interferometry

NASA Technical Reports Server (NTRS)

Labadie, L.; Leger, A.; Malbet, F.; Danchi, William C.; Lopez, B.

2013-01-01

We address the question of space interferometry following the recent outcome of the science themes selection by ESA for the L2/L3 missions slots. We review the current context of exoplanetary sciences and its impact for an interferometric mission. We argue that space interferometry will make a major step forward when the scientific communities interested in this technique will merge their efforts into a coherent technology development plan.

Very long baseline interferometry applied to polar motion, relativity, and geodesy. Ph. D. thesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, C.

1978-01-01

The causes and effects of diurnal polar motion are described. An algorithm was developed for modeling the effects on very long baseline interferometry observables. A selection was made between two three-station networks for monitoring polar motion. The effects of scheduling and the number of sources observed on estimated baseline errors are discussed. New hardware and software techniques in very long baseline interferometry are described.

The Wide-Field Imaging Interferometry Testbed: Recent Progress

NASA Technical Reports Server (NTRS)

Rinehart, Stephen A.

2010-01-01

The Wide-Field Imaging Interferometry Testbed (WIIT) at NASA's Goddard Space Flight Center was designed to demonstrate the practicality and application of techniques for wide-field spatial-spectral ("double Fourier") interferometry. WIIT is an automated system, and it is now producing substantial amounts of high-quality data from its state-of-the-art operating environment, Goddard's Advanced Interferometry and Metrology Lab. In this paper, we discuss the characterization and operation of the testbed and present the most recent results. We also outline future research directions. A companion paper within this conference discusses the development of new wide-field double Fourier data analysis algorithms.

High-rotational symmetry lattices fabricated by moiré nanolithography.

PubMed

Lubin, Steven M; Zhou, Wei; Hryn, Alexander J; Huntington, Mark D; Odom, Teri W

2012-09-12

This paper describes a new nanofabrication method, moiré nanolithography, that can fabricate subwavelength lattices with high-rotational symmetries. By exposing elastomeric photomasks sequentially at multiple offset angles, we created arrays with rotational symmetries as high as 36-fold, which is three times higher than quasiperiodic lattices (≤12-fold) and six times higher than two-dimensional periodic lattices (≤6-fold). Because these moiré nanopatterns can be generated over wafer-scale areas, they are promising for a range of photonic applications, especially those that require broadband, omnidirectional absorption of visible light.

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

PubMed

Wang, Kaiwei; Martin, Haydn; Jiang, Xiangqian

2008-02-01

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.

Validation of Noninvasive MOEMS-Assisted Measurement System Based on CCD Sensor for Radial Pulse Analysis

PubMed Central

Malinauskas, Karolis; Palevicius, Paulius; Ragulskis, Minvydas; Ostasevicius, Vytautas; Dauksevicius, Rolanas

2013-01-01

Examination of wrist radial pulse is a noninvasive diagnostic method, which occupies a very important position in Traditional Chinese Medicine. It is based on manual palpation and therefore relies largely on the practitioner′s subjective technical skills and judgment. Consequently, it lacks reliability and consistency, which limits practical applications in clinical medicine. Thus, quantifiable characterization of the wrist pulse diagnosis method is a prerequisite for its further development and widespread use. This paper reports application of a noninvasive CCD sensor-based hybrid measurement system for radial pulse signal analysis. First, artery wall deformations caused by the blood flow are calibrated with a laser triangulation displacement sensor, following by the measurement of the deformations with projection moiré method. Different input pressures and fluids of various viscosities are used in the assembled artificial blood flow system in order to test the performance of laser triangulation technique with detection sensitivity enhancement through microfabricated retroreflective optical element placed on a synthetic vascular graft. Subsequently, the applicability of double-exposure whole-field projection moiré technique for registration of blood flow pulses is considered: a computational model and representative example are provided, followed by in vitro experiment performed on a vascular graft with artificial skin atop, which validates the suitability of the technique for characterization of skin surface deformations caused by the radial pulsation. PMID:23609803

Validation of noninvasive MOEMS-assisted measurement system based on CCD sensor for radial pulse analysis.

PubMed

Malinauskas, Karolis; Palevicius, Paulius; Ragulskis, Minvydas; Ostasevicius, Vytautas; Dauksevicius, Rolanas

2013-04-22

Examination of wrist radial pulse is a noninvasive diagnostic method, which occupies a very important position in Traditional Chinese Medicine. It is based on manual palpation and therefore relies largely on the practitioner's subjective technical skills and judgment. Consequently, it lacks reliability and consistency, which limits practical applications in clinical medicine. Thus, quantifiable characterization of the wrist pulse diagnosis method is a prerequisite for its further development and widespread use. This paper reports application of a noninvasive CCD sensor-based hybrid measurement system for radial pulse signal analysis. First, artery wall deformations caused by the blood flow are calibrated with a laser triangulation displacement sensor, following by the measurement of the deformations with projection moiré method. Different input pressures and fluids of various viscosities are used in the assembled artificial blood flow system in order to test the performance of laser triangulation technique with detection sensitivity enhancement through microfabricated retroreflective optical element placed on a synthetic vascular graft. Subsequently, the applicability of double-exposure whole-field projection moiré technique for registration of blood flow pulses is considered: a computational model and representative example are provided, followed by in vitro experiment performed on a vascular graft with artificial skin atop, which validates the suitability of the technique for characterization of skin surface deformations caused by the radial pulsation.

Dual-hologram shearing interferometry with regulated sensitivity

NASA Astrophysics Data System (ADS)

Toker, Gregory R.; Levin, Daniel

1998-07-01

A novel optical diagnostic technique, namely, a dual hologram shearing interferometry with regulated sensitivity, is proposed for visualization and measuring the density gradients of compressible flows in wind tunnels. It has advantages over conventional shearing interferometry in both accuracy and sensitivity. The method is especially useful for strong turbulent or unsteady regions of the flows including shock flows. The interferometer proved to be insensitive to mechanical vibrations and allowed to record holograms during the noisy wind tunnel run. The proposed approach was demonstrated by its application to a supersonic flow over spherically blunted and sharp nose cone/cylinder models. It is believed that the technique will become an effective tool for receiving optical data in many flow facilities.

Moiré-Modulated Conductance of Hexagonal Boron Nitride Tunnel Barriers.

PubMed

Summerfield, Alex; Kozikov, Aleksey; Cheng, Tin S; Davies, Andrew; Cho, Yong-Jin; Khlobystov, Andrei N; Mellor, Christopher J; Foxon, C Thomas; Watanabe, Kenji; Taniguchi, Takashi; Eaves, Laurence; Novoselov, Kostya S; Novikov, Sergei V; Beton, Peter H

2018-06-27

Monolayer hexagonal boron nitride (hBN) tunnel barriers investigated using conductive atomic force microscopy reveal moiré patterns in the spatial maps of their tunnel conductance consistent with the formation of a moiré superlattice between the hBN and an underlying highly ordered pyrolytic graphite (HOPG) substrate. This variation is attributed to a periodc modulation of the local density of states and occurs for both exfoliated hBN barriers and epitaxially grown layers. The epitaxial barriers also exhibit enhanced conductance at localized subnanometer regions which are attributed to exposure of the substrate to a nitrogen plasma source during the high temperature growth process. Our results show clearly a spatial periodicity of tunnel current due to the formation of a moiré superlattice and we argue that this can provide a mechanism for elastic scattering of charge carriers for similar interfaces embedded in graphene/hBN resonant tunnel diodes.

Moiré-reduction method for slanted-lenticular-based quasi-three-dimensional displays

NASA Astrophysics Data System (ADS)

Zhuang, Zhenfeng; Surman, Phil; Zhang, Lei; Rawat, Rahul; Wang, Shizheng; Zheng, Yuanjin; Sun, Xiao Wei

2016-12-01

In this paper we present a method for determining the preferred slanted angle for a lenticular film that minimizes moiré patterns in quasi-three-dimensional (Q3D) displays. We evaluate the preferred slanted angles of the lenticular film for the stripe-type sub-pixel structure liquid crystal display (LCD) panel. Additionally, the sub-pixels mapping algorithm of the specific angle is proposed to assign the images to either the right or left eye channel. A Q3D display prototype is built. Compared with the conventional SLF, this newly implemented Q3D display can not only eliminate moiré patterns but also provide 3D images in both portrait and landscape orientations. It is demonstrated that the developed slanted lenticular film (SLF) provides satisfactory 3D images by employing a compact structure, minimum moiré patterns and stabilized 3D contrast.

Lattice-Matched Epitaxial Graphene Grown on Boron Nitride.

PubMed

Davies, Andrew; Albar, Juan D; Summerfield, Alex; Thomas, James C; Cheng, Tin S; Korolkov, Vladimir V; Stapleton, Emily; Wrigley, James; Goodey, Nathan L; Mellor, Christopher J; Khlobystov, Andrei N; Watanabe, Kenji; Taniguchi, Takashi; Foxon, C Thomas; Eaves, Laurence; Novikov, Sergei V; Beton, Peter H

2018-01-10

Lattice-matched graphene on hexagonal boron nitride is expected to lead to the formation of a band gap but requires the formation of highly strained material and has not hitherto been realized. We demonstrate that aligned, lattice-matched graphene can be grown by molecular beam epitaxy using substrate temperatures in the range 1600-1710 °C and coexists with a topologically modified moiré pattern with regions of strained graphene which have giant moiré periods up to ∼80 nm. Raman spectra reveal narrow red-shifted peaks due to isotropic strain, while the giant moiré patterns result in complex splitting of Raman peaks due to strain variations across the moiré unit cell. The lattice-matched graphene has a lower conductance than both the Frenkel-Kontorova-type domain walls and also the topological defects where they terminate. We relate these results to theoretical models of band gap formation in graphene/boron nitride heterostructures.

A median-Gaussian filtering framework for Moiré pattern noise removal from X-ray microscopy image.

PubMed

Wei, Zhouping; Wang, Jian; Nichol, Helen; Wiebe, Sheldon; Chapman, Dean

2012-02-01

Moiré pattern noise in Scanning Transmission X-ray Microscopy (STXM) imaging introduces significant errors in qualitative and quantitative image analysis. Due to the complex origin of the noise, it is difficult to avoid Moiré pattern noise during the image data acquisition stage. In this paper, we introduce a post-processing method for filtering Moiré pattern noise from STXM images. This method includes a semi-automatic detection of the spectral peaks in the Fourier amplitude spectrum by using a local median filter, and elimination of the spectral noise peaks using a Gaussian notch filter. The proposed median-Gaussian filtering framework shows good results for STXM images with the size of power of two, if such parameters as threshold, sizes of the median and Gaussian filters, and size of the low frequency window, have been properly selected. Copyright © 2011 Elsevier Ltd. All rights reserved.

Measurement of Three-dimensional Density Distributions by Holographic Interferometry and Computer Tomography

NASA Technical Reports Server (NTRS)

Vest, C. M.

1982-01-01

The use of holographic interferometry to measure two and threedimensional flows and the interpretation of multiple-view interferograms with computer tomography are discussed. Computational techniques developed for tomography are reviewed. Current research topics are outlined including the development of an automated fringe readout system, optimum reconstruction procedures for when an opaque test model is present in the field, and interferometry and tomography with strongly refracting fields and shocks.

Hinge-line Migration of Petermann Gletscher, North Greenland, Detected Using Satellite Radar Interferometry

NASA Technical Reports Server (NTRS)

Rignot, Eric

1998-01-01

The synthetic-aperture radar interferometry technique is used to detect the migration of the limit of tidal flexing, or hinge line, of the floating ice tongue of Petermann Gletscher, a major outlet glacier of north Greenland.

Diffraction gratings used as identifying markers

DOEpatents

Deason, V.A.; Ward, M.B.

1991-03-26

A finely detailed diffraction grating is applied to an object as an identifier or tag which is unambiguous, difficult to duplicate, or remove and transfer to another item, and can be read and compared with prior readings with relative ease. The exact pattern of the diffraction grating is mapped by diffraction moire techniques and recorded for comparison with future readings of the same grating. 7 figures.

Training-based descreening.

PubMed

Siddiqui, Hasib; Bouman, Charles A

2007-03-01

Conventional halftoning methods employed in electrophotographic printers tend to produce Moiré artifacts when used for printing images scanned from printed material, such as books and magazines. We present a novel approach for descreening color scanned documents aimed at providing an efficient solution to the Moiré problem in practical imaging devices, including copiers and multifunction printers. The algorithm works by combining two nonlinear image-processing techniques, resolution synthesis-based denoising (RSD), and modified smallest univalue segment assimilating nucleus (SUSAN) filtering. The RSD predictor is based on a stochastic image model whose parameters are optimized beforehand in a separate training procedure. Using the optimized parameters, RSD classifies the local window around the current pixel in the scanned image and applies filters optimized for the selected classes. The output of the RSD predictor is treated as a first-order estimate to the descreened image. The modified SUSAN filter uses the output of RSD for performing an edge-preserving smoothing on the raw scanned data and produces the final output of the descreening algorithm. Our method does not require any knowledge of the screening method, such as the screen frequency or dither matrix coefficients, that produced the printed original. The proposed scheme not only suppresses the Moiré artifacts, but, in addition, can be trained with intrinsic sharpening for deblurring scanned documents. Finally, once optimized for a periodic clustered-dot halftoning method, the same algorithm can be used to inverse halftone scanned images containing stochastic error diffusion halftone noise.

Experimental investigation of gas flow rate and electric field effect on refractive index and electron density distribution of cold atmospheric pressure-plasma by optical method, Moiré deflectometry

NASA Astrophysics Data System (ADS)

Khanzadeh, Mohammad; Jamal, Fatemeh; Shariat, Mahdi

2018-04-01

Nowadays, cold atmospheric-pressure (CAP) helium plasma jets are widely used in material processing devices in various industries. Researchers often use indirect and spectrometric methods for measuring the plasma parameters which are very expensive. In this paper, for the first time, characterization of CAP, i.e., finding its parameters such as refractive index and electron density distribution, was carried out using an optical method, Moiré deflectometry. This method is a wave front analysis technique based on geometric optics. The advantages of this method are simplicity, high accuracy, and low cost along with the non-contact, non-destructive, and direct measurement of CAP parameters. This method demonstrates that as the helium gas flow rate decreases, the refractive index increases. Also, we must note that the refractive index is larger in the gas flow consisting of different flow rates of plasma comparing with the gas flow without the plasma.

Spatial phase-shift dual-beam speckle interferometry.

PubMed

Gao, Xinya; Yang, Lianxiang; Wang, Yonghong; Zhang, Boyang; Dan, Xizuo; Li, Junrui; Wu, Sijin

2018-01-20

The spatial phase-shift technique has been successfully applied to an out-of-plane speckle interferometry system. Its application to a pure in-plane sensitive system has not been reported yet. This paper presents a novel optical configuration that enables the application of the spatial phase-shift technique to pure in-plane sensitive dual-beam speckle interferometry. The new spatial phase-shift dual-beam speckle interferometry (SPS-DBSP) uses a dual-beam in-plane electronic speckle pattern interferometry configuration with individual aperture shears, avoiding the interference in the object plane by the use of a low-coherence source, and different optical paths. The measured object is illuminated by two incoherent beams that are generated by a delay line, which is larger than the coherence length of the laser. The two beams reflected from the object surface interfere with each other at the CCD plane because of different optical paths. A spatial phase shift is introduced by the angle between the two apertures when they are mapped to the same optical axis. The phase of the in-plane deformation can directly be extracted from the speckle patterns by the Fourier transform method. The capability of SPS-DBSI is demonstrated by theoretical discussion as well as experiments.

The Path to Interferometry in Space

NASA Technical Reports Server (NTRS)

Rinehart, S. A.; Savini, G.; Holland, W.; Absil, O.; Defrere, D.; Spencer, L.; Leisawitz, D.; Rizzo, M.; Juanola-Parramon, R.; Mozurkewich, D.

2016-01-01

For over two decades, astronomers have considered the possibilities for interferometry in space. The first of these missions was the Space Interferometry Mission (SIM), but that was followed by missions for studying exoplanets (e.g Terrestrial Planet Finder, Darwin), and then far-infrared interferometers (e.g. the Space Infrared Interferometric Telescope, the Far-Infrared Interferometer). Unfortunately, following the cancellation of SIM, the future for space-based interferometry has been in doubt, and the interferometric community needs to reevaluate the path forward. While interferometers have strong potential for scientific discovery, there are technological developments still needed, and continued maturation of techniques is important for advocacy to the broader astronomical community. We review the status of several concepts for space-based interferometry, and look for possible synergies between missions oriented towards different science goals.

Evolution of Moiré Profiles from van der Waals Superstructures of Boron Nitride Nanosheets

PubMed Central

Liao, Yunlong; Cao, Wei; Connell, John W.; Chen, Zhongfang; Lin, Yi

2016-01-01

Two-dimensional (2D) van der Waals (vdW) superstructures, or vdW solids, are formed by the precise restacking of 2D nanosheet lattices, which can lead to unique physical and electronic properties that are not available in the parent nanosheets. Moiré patterns formed by the crystalline mismatch between adjacent nanosheets are the most direct features for vdW superstructures under microscopic imaging. In this article, transmission electron microscopy (TEM) observation of hexagonal Moiré patterns with unusually large micrometer-sized lateral areas (up to ~1 μm2) and periodicities (up to ~50 nm) from restacking of liquid exfoliated hexagonal boron nitride nanosheets (BNNSs) is reported. This observation was attributed to the long range crystallinity and the contaminant-free surfaces of these chemically inert nanosheets. Parallel-line-like Moiré fringes with similarly large periodicities were also observed. The simulations and experiments unambiguously revealed that the hexagonal patterns and the parallel fringes originated from the same rotationally mismatched vdW stacking of BNNSs and can be inter-converted by simply tilting the TEM specimen following designated directions. This finding may pave the way for further structural decoding of other 2D vdW superstructure systems with more complex Moiré images. PMID:27188697

An examination of along-track interferometry for detecting ground moving targets

NASA Technical Reports Server (NTRS)

Chen, Curtis W.; Chapin, Elaine; Muellerschoen, Ron; Hensley, Scott

2005-01-01

Along-track interferometry (ATI) is an interferometric synthetic aperture radar technique primarily used to measure Earth-surface velocities. We present results from an airborne experiment demonstrating phenomenology specific to the context of observing discrete ground targets moving admidst a stationary clutter background.

Advanced technology development multi-color holography

NASA Technical Reports Server (NTRS)

Vikram, Chandra S.

1993-01-01

This is the final report of the Multi-color Holography project. The comprehensive study considers some strategic aspects of multi-color holography. First, various methods of available techniques for accurate fringe counting are reviewed. These are heterodyne interferometry, quasi-heterodyne interferometry, and phase-shifting interferometry. Phase-shifting interferometry was found to be the most suitable for multi-color holography. Details of experimentation with a sugar solution are also reported where better than 1/200 of a fringe order measurement capability was established. Rotating plate glass phase shifter was used for the experimentation. The report then describes the possible role of using more than two wavelengths with special reference-to-object beam intensity ratio needs in multicolor holography. Some specific two- and three-color cases are also described in detail. Then some new analysis methods of the reconstructed wavefront are considered. These are deflectometry, speckle metrology, confocal optical signal processing, and phase shifting technique related applications. Finally, design aspects of an experimental breadboard are presented.

Double-path acquisition of pulse wave transit time and heartbeat using self-mixing interferometry

NASA Astrophysics Data System (ADS)

Wei, Yingbin; Huang, Wencai; Wei, Zheng; Zhang, Jie; An, Tong; Wang, Xiulin; Xu, Huizhen

2017-06-01

We present a technique based on self-mixing interferometry for acquiring the pulse wave transit time (PWTT) and heartbeat. A signal processing method based on Continuous Wavelet Transform and Hilbert Transform is applied to extract potentially useful information in the self-mixing interference (SMI) signal, including PWTT and heartbeat. Then, some cardiovascular characteristics of the human body are easily acquired without retrieving the SMI signal by complicated algorithms. Experimentally, the PWTT is measured on the finger and the toe of the human body using double-path self-mixing interferometry. Experimental statistical data show the relation between the PWTT and blood pressure, which can be used to estimate the systolic pressure value by fitting. Moreover, the measured heartbeat shows good agreement with that obtained by a photoplethysmography sensor. The method that we demonstrate, which is based on self-mixing interferometry with significant advantages of simplicity, compactness and non-invasion, effectively illustrates the viability of the SMI technique for measuring other cardiovascular signals.

Modulation of Polarization for Phase Extraction in Holographic Interferometry with Two References

NASA Astrophysics Data System (ADS)

Rodriguez-Zurita, G.; Vázquez-Castillo, J.-F.; Toto-Arellano, N.-I.; Meneses-Fabian, C.; Jiménez-Montero, L.-E.

2010-04-01

Heterodyne holographic interferometry allows high accuracy for phase-difference extraction between two wave fronts, especially when they are previously recorded in the same recording medium. In part, this is because the wave fronts can be affected by the recording process in a very similar way. The double reconstruction of a double-exposure hologram with two independent references results in a two-beam holographic interferometer with an arm conveying a wave modulated in frequency when using heterodyne techniques. The heterodyne frequency has been usually introduced with a plane mirror attached to a piezo-electric stack driven with a suitable variable power supply. For holographic interferometry, however, less attention has been devoted to alternative phase retrieval variants as, for example, phase-shifting with modulation of polarization or Fourier methods. In this work, we propose and demonstrate the basic capabilities of modulation of polarization performing as a phase-shifting technique for holographic interferometry with two references in a phase-stepping scheme. Experimental results are provided.

Biolayer Interferometry: A Novel Method to Elucidate Protein-Protein and Protein-DNA Interactions in the Mitochondrial DNA Replisome.

PubMed

Ciesielski, Grzegorz L; Hytönen, Vesa P; Kaguni, Laurie S

2016-01-01

A lack of effective treatment for mitochondrial diseases prompts scientists to investigate the molecular processes that underlie their development. The major cause of mitochondrial diseases is dysfunction of the sole mitochondrial DNA polymerase, DNA polymerase γ (Pol γ). The development of treatment strategies will require a detailed characterization of the molecular properties of Pol γ. A novel technique, biolayer interferometry, allows one to monitor molecular interactions in real time, thus providing an insight into the kinetics of the process. Here, we present an application of the biolayer interferometry technique to characterize the fundamental reactions that Pol γ undergoes during the initiation phase of mitochondrial DNA replication: holoenzyme formation and binding to the primer-template.

Biolayer Interferometry: A Novel Method to Elucidate Protein–Protein and Protein–DNA Interactions in the Mitochondrial DNA Replisome

PubMed Central

Ciesielski, Grzegorz L.; Hytönen, Vesa P.; Kaguni, Laurie S.

2015-01-01

A lack of effective treatment for mitochondrial diseases prompts scientists to investigate the molecular processes that underlie their development. The major cause of mitochondrial diseases is dysfunction of the sole mitochondrial DNA polymerase, DNA polymerase γ (Pol γ). The development of treatment strategies will require a detailed characterization of the molecular properties of Pol γ. A novel technique, biolayer interferometry, allows one to monitor molecular interactions in real time, thus providing an insight into the kinetics of the process. Here, we present an application of the biolayer interferometry technique to characterize the fundamental reactions that Pol γ undergoes during the initiation phase of mitochondrial DNA replication: holoenzyme formation and binding to the primer-template. PMID:26530686

Application of Radar Data to Remote Sensing and Geographical Information Systems

NASA Technical Reports Server (NTRS)

vanZyl, Jakob J.

2000-01-01

The field of synthetic aperture radar changed dramatically over the past decade with the operational introduction of advance radar techniques such as polarimetry and interferometry. Radar polarimetry became an operational research tool with the introduction of the NASA/JPL AIRSAR system in the early 1980's, and reached a climax with the two SIR-C/X-SAR flights on board the space shuttle Endeavour in April and October 1994. Radar interferometry received a tremendous boost when the airborne TOPSAR system was introduced in 1991 by NASA/JPL, and further when data from the European Space Agency ERS-1 radar satellite became routinely available in 1991. Several airborne interferometric SAR systems are either currently operational, or are about to be introduced. Radar interferometry is a technique that allows one to map the topography of an area automatically under all weather conditions, day or night. The real power of radar interferometry is that the images and digital elevation models are automatically geometrically resampled, and could be imported into GIS systems directly after suitable reformatting. When combined with polarimetry, a technique that uses polarization diversity to gather more information about the geophysical properties of the terrain, a very rich multi-layer data set is available to the remote sensing scientist. This talk will discuss the principles of radar interferometry and polarimetry with specific application to the automatic categorization of land cover. Examples will include images acquired with the NASA/JPL AIRSAR/TOPSAR system in Australia and elsewhere.

Monitoring the englacial fracture state using virtual-reflector seismology

NASA Astrophysics Data System (ADS)

Lindner, F.; Weemstra, C.; Walter, F.; Hadziioannou, C.

2017-12-01

Fracturing and changes in the englacial macroscopic water content change the elastic bulk properties of ice bodies. Small seismic velocity variations, resulting from such changes, can be measured using a technique called coda-wave interferometry. Here, coda refers to the later-arriving, multiply scattered waves. Often, this technique is applied to so-called virtual-source responses, which can be obtained using seismic interferometry (a simple crosscorrelation process). Compared to other media (e.g., the Earth's crust), however, ice bodies exhibit relatively little scattering. This complicates the application of coda-wave interferometry to the retrieved virtual-source responses. In this work, we therefore investigate the applicability of coda-wave interferometry to virtual-source responses obtained using two alternative seismic interferometric techniques, namely, seismic interferometry by multidimensional deconvolution (SI by MDD), and virtual-reflector seismology (VRS). To that end, we use synthetic data, as well as active-source glacier data acquired on Glacier de la Plaine Morte, Switzerland. Both SI by MDD and VRS allow the retrieval of more accurate virtual-source responses. In particular, the dependence of the retrieved virtual-source responses on the illumination pattern is reduced. We find that this results in more accurate glacial phase-velocity estimates. In addition, VRS introduces virtual reflections from a receiver contour (partly) enclosing the medium of interest. By acting as a sort of virtual reverberation, the coda resulting from the application of VRS significantly increases seismic monitoring capabilities, in particular in cases where natural scattering coda is not available.

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.

International Congress on High Speed Photography and Photonics, 17th, Pretoria, Republic of South Africa, Sept. 1-5, 1986, Proceedings. Volumes 1 & 2

NASA Astrophysics Data System (ADS)

McDowell, M. W.; Hollingworth, D.

1986-01-01

The present conference discusses topics in mining applications of high speed photography, ballistic, shock wave and detonation studies employing high speed photography, laser and X-ray diagnostics, biomechanical photography, millisec-microsec-nanosec-picosec-femtosec photographic methods, holographic, schlieren, and interferometric techniques, and videography. Attention is given to such issues as the pulse-shaping of ultrashort optical pulses, the performance of soft X-ray streak cameras, multiple-frame image tube operation, moire-enlargement motion-raster photography, two-dimensional imaging with tomographic techniques, photochron TV streak cameras, and streak techniques in detonics.

Zone plate lenses for X-ray microscopy

NASA Astrophysics Data System (ADS)

Vladimirsky, Y.; Kern, D. P.; Chang, T. H. P.; Attwood, D. T.; Iskander, N.; Rothman, S.; McQuaide, K.; Kirz, J.; Ade, H.; McNulty, I.; Rarback, H.; Shu, D.

1988-04-01

Fresnel zone plate lenses with feature sizes as small as 50 nm have been constructed and used in the Stony Brook/NSLS scanning X-ray microscope with 3.1 nm radiation from Brookhaven's X-17 mini-undulator. The zone plates were fabricated at IBM using electron beam writing techniques, moiré pattern techniques to monitor ellipticity, and a double development/double plating technique to provide additional thickness in the central region. A spatial resolution down to 75 nm was measured in the microscope. Using these zone plates, biological images were obtained of unaltered subcellular components. The images highlight protein concentration in unsectioned, unfixed, and unstained enzymatic granules in an aqueous environment.

Synthetic aperture imaging in astronomy and aerospace: introduction.

PubMed

Creech-Eakman, Michelle J; Carney, P Scott; Buscher, David F; Shao, Michael

2017-05-01

Aperture synthesis methods allow the reconstruction of images with the angular resolutions exceeding that of extremely large monolithic apertures by using arrays of smaller apertures together in combination. In this issue we present several papers with techniques relevant to amplitude interferometry, laser radar, and intensity interferometry applications.

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.

Electronic holographic moire in the micron range

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Sciammarella, Federico M.

2001-06-01

The basic theory behind microscopic electronic holographic moire is presented. Conditions of observation are discussed, and optimal parameters are established. An application is presented as an example where experimental result are statistically analyzed and successfully correlated with an independent method of measurement of the same quantity.

Large radius of curvature measurement based on virtual quadratic Newton rings phase-shifting moiré-fringes measurement method in a nonnull interferometer.

PubMed

Yang, Zhongming; Wang, Kailiang; Cheng, Jinlong; Gao, Zhishan; Yuan, Qun

2016-06-10

We have proposed a virtual quadratic Newton rings phase-shifting moiré-fringes measurement method in a nonnull interferometer to measure the large radius of curvature for a spherical surface. In a quadratic polar coordinate system, linear carrier testing Newton rings interferogram and virtual Newton rings interferogram form the moiré fringes. It is possible to retrieve the wavefront difference data between the testing and standard spherical surface from the moiré fringes after low-pass filtering. Based on the wavefront difference data, we deduced a precise formula to calculate the radius of curvature in the quadratic polar coordinate system. We calculated the retrace error in the nonnull interferometer using the multi-configuration model of the nonnull interferometric system in ZEMAX. Our experimental results indicate that the measurement accuracy is better than 0.18% for a spherical mirror with a radius of curvature of 41,400 mm.

Theory of optical absorption by interlayer excitons in transition metal dichalcogenide heterobilayers

NASA Astrophysics Data System (ADS)

Wu, Fengcheng; Lovorn, Timothy; MacDonald, A. H.

2018-01-01

We present a theory of optical absorption by interlayer excitons in a heterobilayer formed from transition metal dichalcogenides. The theory accounts for the presence of small relative rotations that produce a momentum shift between electron and hole bands located in different layers, and a moiré pattern in real space. Because of the momentum shift, the optically active interlayer excitons are located at the moiré Brillouin zone's corners, instead of at its center, and would have elliptical optical selection rules if the individual layers were translationally invariant. We show that the exciton moiré potential energy restores circular optical selection rules by coupling excitons with different center of mass momenta. A variety of interlayer excitons with both senses of circular optical activity, and energies that are tunable by twist angle, are present at each valley. The lowest energy exciton states are generally localized near the exciton potential energy minima. We discuss the possibility of using the moiré pattern to achieve scalable two-dimensional arrays of nearly identical quantum dots.

Quantitative analysis and temperature-induced variations of moiré pattern in fiber-coupled imaging sensors.

PubMed

Karbasi, Salman; Arianpour, Ashkan; Motamedi, Nojan; Mellette, William M; Ford, Joseph E

2015-06-10

Imaging fiber bundles can map the curved image surface formed by some high-performance lenses onto flat focal plane detectors. The relative alignment between the focal plane array pixels and the quasi-periodic fiber-bundle cores can impose an undesirable space variant moiré pattern, but this effect may be greatly reduced by flat-field calibration, provided that the local responsivity is known. Here we demonstrate a stable metric for spatial analysis of the moiré pattern strength, and use it to quantify the effect of relative sensor and fiber-bundle pitch, and that of the Bayer color filter. We measure the thermal dependence of the moiré pattern, and the achievable improvement by flat-field calibration at different operating temperatures. We show that a flat-field calibration image at a desired operating temperature can be generated using linear interpolation between white images at several fixed temperatures, comparing the final image quality with an experimentally acquired image at the same temperature.

Stepwise self-assembly of C60 mediated by atomic scale moiré magnifiers

NASA Astrophysics Data System (ADS)

Gruznev, D. V.; Matetskiy, A. V.; Bondarenko, L. V.; Utas, O. A.; Zotov, A. V.; Saranin, A. A.; Chou, J. P.; Wei, C. M.; Lai, M. Y.; Wang, Y. L.

2013-04-01

Self-assembly of atoms or molecules on a crystal surface is considered one of the most promising methods to create molecular devices. Here we report a stepwise self-assembly of C60 molecules into islands with unusual shapes and preferred sizes on a gold-indium-covered Si(111) surface. Specifically, 19-mer islands prefer a non-compact boomerang shape, whereas hexagonal 37-mer islands exhibit extraordinarily enhanced stability and abundance. The stepwise self-assembly is mediated by the moiré interference between an island with its underlying lattice, which essentially maps out the adsorption-energy landscape of a C60 on different positions of the surface with a lateral magnification factor and dictates the probability for the subsequent attachment of C60 to an island’s periphery. Our discovery suggests a new method for exploiting the moiré interference to dynamically assist the self-assembly of particles and provides an unexplored tactic of engineering atomic scale moiré magnifiers to facilitate the growth of monodispersed mesoscopic structures.

Strain-Engineered Graphene Grown on Hexagonal Boron Nitride by Molecular Beam Epitaxy

PubMed Central

Summerfield, Alex; Davies, Andrew; Cheng, Tin S.; Korolkov, Vladimir V.; Cho, YongJin; Mellor, Christopher J.; Foxon, C. Thomas; Khlobystov, Andrei N.; Watanabe, Kenji; Taniguchi, Takashi; Eaves, Laurence; Novikov, Sergei V.; Beton, Peter H.

2016-01-01

Graphene grown by high temperature molecular beam epitaxy on hexagonal boron nitride (hBN) forms continuous domains with dimensions of order 20 μm, and exhibits moiré patterns with large periodicities, up to ~30 nm, indicating that the layers are highly strained. Topological defects in the moiré patterns are observed and attributed to the relaxation of graphene islands which nucleate at different sites and subsequently coalesce. In addition, cracks are formed leading to strain relaxation, highly anisotropic strain fields, and abrupt boundaries between regions with different moiré periods. These cracks can also be formed by modification of the layers with a local probe resulting in the contraction and physical displacement of graphene layers. The Raman spectra of regions with a large moiré period reveal split and shifted G and 2D peaks confirming the presence of strain. Our work demonstrates a new approach to the growth of epitaxial graphene and a means of generating and modifying strain in graphene. PMID:26928710

Directed Assembly of Molecules on Graphene/Ru(0001)

NASA Astrophysics Data System (ADS)

Zhang, L. Z.; Zhang, H. G.; Sun, J. T.; Pan, Y.; Liu, Q.; Mao, J. H.; Zhou, H. T.; Low, T.; Guo, H. M.; Du, S. X.; Gao, H.-J.

2012-02-01

Recently, the graphene monolayers have been seen to adopt a superstructure - moir'e pattern - on Ru(0001). By using low temperature scanning tunneling spectroscopy, we identified the laterally localized electronic states on this system. The individual states are separated by 3 nm and comprise regions of about 90 carbon atoms. This constitutes a highly regular quantum dot-array with molecular precision. It is evidenced by quantum well resonances with energies that relate to the corrugation of the graphene layer. By using scanning tunneling microscopy/spectroscopy, we demonstrate the selective adsorption and formation of ordered molecular arrays of FePc and pentacene molecules on the graphene/Ru(0001) templates. With in-depth investigations of the molecular adsorption and assembly processes we reveal the existence lateral electric dipoles in the epitaxial graphene monolayers and the capability of the dipoles in directing and driving the molecular adsorption and assembly. When increasing the molecular coverage, we observed the formation of regular Kagome lattices that duplicate the lattice of the moir'e pattern of monolayer graphene.

Beam shuttering interferometer and method

DOEpatents

Deason, V.A.; Lassahn, G.D.

1993-07-27

A method and apparatus resulting in the simplification of phase shifting interferometry by eliminating the requirement to know the phase shift between interferograms or to keep the phase shift between interferograms constant. The present invention provides a simple, inexpensive means to shutter each independent beam of the interferometer in order to facilitate the data acquisition requirements for optical interferometry and phase shifting interferometry. By eliminating the requirement to know the phase shift between interferograms or to keep the phase shift constant, a simple, economical means and apparatus for performing the technique of phase shifting interferometry is provide which, by thermally expanding a fiber optical cable changes the optical path distance of one incident beam relative to another.

Beam shuttering interferometer and method

DOEpatents

Deason, Vance A.; Lassahn, Gordon D.

1993-01-01

A method and apparatus resulting in the simplification of phase shifting interferometry by eliminating the requirement to know the phase shift between interferograms or to keep the phase shift between interferograms constant. The present invention provides a simple, inexpensive means to shutter each independent beam of the interferometer in order to facilitate the data acquisition requirements for optical interferometry and phase shifting interferometry. By eliminating the requirement to know the phase shift between interferograms or to keep the phase shift constant, a simple, economical means and apparatus for performing the technique of phase shifting interferometry is provide which, by thermally expanding a fiber optical cable changes the optical path distance of one incident beam relative to another.

Analysis of the principal component algorithm in phase-shifting interferometry.

PubMed

Vargas, J; Quiroga, J Antonio; Belenguer, T

2011-06-15

We recently presented a new asynchronous demodulation method for phase-sampling interferometry. The method is based in the principal component analysis (PCA) technique. In the former work, the PCA method was derived heuristically. In this work, we present an in-depth analysis of the PCA demodulation method.

Fracture Analysis of Particulate Reinforced Metal Matrix Composites

NASA Technical Reports Server (NTRS)

Min, James B.; Cornie, James A.

2013-01-01

A fracture analysis of highly loaded particulate reinforced composites was performed using laser moire interferometry to measure the displacements within the plastic zone at the tip of an advancing crack. Ten castings were made of five different particulate reinforcement-aluminum alloy combinations. Each casting included net-shape specimens which were used for the evaluation of fracture toughness, tensile properties, and flexure properties resulting in an extensive materials properties data. Measured fracture toughness range from 14.1 MPa for an alumina reinforced 356 aluminum alloy to 23.9 MPa for a silicon carbide reinforced 2214 aluminum alloy. For the combination of these K(sub Ic) values and the measured tensile strengths, the compact tension specimens were too thin to yield true plane strain K(sub Ic) values. All materials exhibited brittle behavior characterized by very small tensile ductility suggesting that successful application of these materials requires that the design stresses be below the elastic limit. Probabilistic design principles similar to those used with ceramics are recommended when using these materials. Such principles would include the use of experimentally determined design allowables. In the absence of thorough testing, a design allowable stress of 60 percent of the measured ultimate tensile stress is recommended.

Moiré patterns in doubly differential electron-momentum distributions in atomic ionization by mid-infrared lasers

NASA Astrophysics Data System (ADS)

Dran, Martín; Arbó, Diego G.

2018-05-01

We analyze the doubly differential electron momentum distribution in above-threshold ionization of atomic hydrogen by a linearly polarized mid-infrared laser pulse. We reproduce side rings in the momentum distribution with forward-backward symmetry previously observed by Lemell et al. [Phys. Rev. A 87, 013421 (2013), 10.1103/PhysRevA.87.013421], whose origin, as far as we know, has not been explained so far. By developing a Fourier theory of moiré patterns, we demonstrate that such structures stem from the interplay between intra- and intercycle interference patterns which work as two separate grids in the two-dimensional momentum domain. We use a three-dimensional (3D) description based on the saddle-point approximation (SPA) to unravel the nature of these structures. When the periods of the two grids (intra- and intercycle) are similar, principal moiré patterns arise symmetrically as concentric rings in the forward and backward directions at high electron kinetic energy. Higher order moiré patterns are observed and characterized when the period of one grid is multiple of the other. We find a scale law for the position (in momentum space) of the center of the moiré rings in the tunneling regime. We verify the SPA predictions by comparison with time-dependent distorted-wave strong-field approximation calculations and the solutions of the full 3D time-dependent Schrödinger equation.

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.

A demonstration of an independent-station radio interferometry system with 4-cm precision on a 16-km base line. [for geodesy

NASA Technical Reports Server (NTRS)

Thomas, J. B.; Fanselow, J. L.; Macdoran, P. F.; Skjerve, L. J.; Spitzmesser, D. J.; Fliegel, H. F.

1976-01-01

Radio interferometry promises eventually to measure directly, with accuracies of a few centimeters, both whole earth motions and relative crustal motions with respect to an 'inertial' reference frame. Interferometry measurements of arbitrarily long base lines require, however, the development of new techniques for independent-station observation. In connection with the development of such techniques, a series of short base line demonstration experiments has been conducted between two antennas. The experiments were related to a program involving the design of independent-station instrumentation capable of making three-dimensional earth-fixed base line measurements with an accuracy of a few centimeters. Attention is given to the instrumentation used in the experiments, aspects of data analysis, and the experimental results.

Adaptive optics and interferometry

NASA Technical Reports Server (NTRS)

Beichman, Charles A.; Ridgway, Stephen

1991-01-01

Adaptive optics and interferometry, two techniques that will improve the limiting resolution of optical and infrared observations by factors of tens or even thousands, are discussed. The real-time adjustment of optical surfaces to compensate for wavefront distortions will improve image quality and increase sensitivity. The phased operation of multiple telescopes separated by large distances will make it possible to achieve very high angular resolution and precise positional measurements. Infrared and optical interferometers that will manipulate light beams and measure interference directly are considered. Angular resolutions of single telescopes will be limited to around 10 milliarcseconds even using the adaptive optics techniques. Interferometry would surpass this limit by a factor of 100 or more. Future telescope arrays with 100-m baselines (resolution of 2.5 milliarcseconds at a 1-micron wavelength) are also discussed.

Projection Moire measurement of the deflection of composite plates subject to bird strike impact

NASA Astrophysics Data System (ADS)

Shulev, A.; Van Paepegem, W.; Harizanova, J.; Moentjens, A.; Degrieck, J.; Sainov, V.

2007-06-01

For the new generation aircraft families, the use of fibre-reinforced plastics is considered for the leading edge of the wings. However, this leading edge is very prone to bird strike impact. This paper presents the use of the projection moire technique to measure the out-of-plane deflections of composite plates subject to bird strike. Very strict constraints with regard to: (i) high speed image acquisition, (ii) vibrations of the impact chamber, and (iii) projection and observation angles - complicated substantially the development of the set-up. Moreover, the high frame rates (12000 fps) required a very intensive illumination. In the optimized configuration, a specially designed grating with gradually changing period is projected by means of special Metal Hydride lamps through one of the side windows of the impact chamber onto the composite plate riveted in a steel frame. The digital high speed camera is mounted on the roof of the impact chamber and records through a mirror the object surface with the projected fringe pattern on it. Numerical routines based on Local Fourier Transform were developed to process the digital images, to extract the phase and the out-of-plane displacements. The phase evaluation is possible due to the carrier frequency nature of the projected moire pattern. This carrier frequency allows separation of the unwanted additive and multiplicative fringe pattern components in the frequency domain via the application of a proper mask. The numerical calculations were calibrated for the bird strike of an aluminium plate, where the plastic deformation could be checked after the test.

Electronic speckle pattern interferometry using vortex beams.

PubMed

Restrepo, René; Uribe-Patarroyo, Néstor; Belenguer, Tomás

2011-12-01

We show that it is possible to perform electronic speckle pattern interferometry (ESPI) using, for the first time to our knowledge, vortex beams as the reference beam. The technique we propose is easy to implement, and the advantages obtained are, among others, environmental stability, lower processing time, and the possibility to switch between traditional ESPI and spiral ESPI. The experimental results clearly show the advantages of using the proposed technique for deformation studies of complex structures. © 2011 Optical Society of America

Status of holographic interferometry at University of Michigan

NASA Technical Reports Server (NTRS)

Vest, Charles

1987-01-01

Reflection holograms were taken of a jet of air injected traverse to a subsonic stream. The technique of reflection holograms allowed maximum viewing angle and minimum distance to the jet. Holographic interferometry is being used to measure the temperature distribution in a growing crystal. Computations of the temperatures are being made. A phase shift interferometer was used to study flows with very weak changes in refractive index, of the order of 1 shift. Tomographic techniques are being developed for strong refractive cases.

The Moire Effect in Physics Teaching.

ERIC Educational Resources Information Center

Bernero, Bruce

1989-01-01

The Moire pattern is the shimmering pattern which looks like an odd interference pattern in window screens or folds of nylon shower curtain. Illustrates some of the ways the effect may be used, including demonstration of wave interference, detection of small displacement, persistence of vision, contour measurement, beats, and optical clearness.…

An In-Depth Analysis of the Cold Boot Attack: Can It Be Used for Sound Forensic Memory Acquisition?

DTIC Science & Technology

2011-01-01

technique, les auteurs font ressortir ses avantages et inconvénients, son applicabilité et sa pertinence pour l’acquisition du contenu de la mémoire...Les auteurs croient qu’une compréhension approfondie de ce phénomène habilitera les enquêteurs en informatique judiciaire à en tirer profit lorsque...individu. Comme l’équipe de Princeton n’a pas spécifiquement examiné l’applicabilité de leur technique à l’informatique judiciaire, les auteurs de la

Electro-optical system for the nondestructive evaluation of bioengineering materials

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Bhat, Gopalakrishna K.; Albertazzi, Armando, Jr.

1991-08-01

The paper presents a system that may be used in a wide range of biomedical fields. The system can be applied in conjunction with different optical techniques: (a) holography, (b) moire method, (c) speckle techniques, (d) photoelasticity. The system has been built in such a way that an operator with average skills will be able to use it; data acquisition and processing are fast and almost automatic. A brief description of the system, its main components and the basic theory behind it, are given. The use of the system is illustrated with examples in orthopedics and in the cardio-vascular area.

A far-infrared spatial/spectral Fourier interferometry laboratory-based testbed instrument

NASA Astrophysics Data System (ADS)

Spencer, Locke D.; Naylor, David A.; Scott, Jeremy P.; Weiler, Vince F.; MacCrimmon, Roderick K.; Sitwell, Geoffrey R. H.; Ade, Peter A. R.

2016-07-01

We describe the current status, including preliminary design, characterization efforts, and recent progress, in the development of a spatial/spectral double Fourier laboratory-based interferometer testbed instrument within the Astronomical Instrumentation Group (AIG) laboratories at the University of Lethbridge, Canada (UL). Supported by CRC, CFI, and NSERC grants, this instrument development will provide laboratory demonstration of spatial-spectral interferometry with a concentration of furthering progress in areas including the development of spatial/spectral interferometry observation, data processing, characterization, and analysis techniques in the Far-Infrared (FIR) region of the electromagnetic spectrum.

Optical long baseline intensity interferometry: prospects for stellar physics

NASA Astrophysics Data System (ADS)

Rivet, Jean-Pierre; Vakili, Farrokh; Lai, Olivier; Vernet, David; Fouché, Mathilde; Guerin, William; Labeyrie, Guillaume; Kaiser, Robin

2018-06-01

More than sixty years after the first intensity correlation experiments by Hanbury Brown and Twiss, there is renewed interest for intensity interferometry techniques for high angular resolution studies of celestial sources. We report on a successful attempt to measure the bunching peak in the intensity correlation function for bright stellar sources with 1 meter telescopes (I2C project). We propose further improvements of our preliminary experiments of spatial interferometry between two 1 m telescopes, and discuss the possibility to export our method to existing large arrays of telescopes.

Laser Interferometry Method as a Novel Tool in Endotoxins Research.

PubMed

Arabski, Michał; Wąsik, Sławomir

2017-01-01

Optical properties of chemical substances are widely used at present for assays thereof in a variety of scientific disciplines. One of the measurement techniques applied in physical sciences, with a potential for novel applications in biology, is laser interferometry. This method enables to record the diffusion properties of chemical substances. Here we describe the novel application of laser interferometry in chitosan interactions with lipopolysaccharide by detection of colistin diffusion. The proposed model could be used in simple measurements of polymer interactions with endotoxins and/or biological active compounds, like antibiotics.

Protein–ligand interactions investigated by thermal shift assays (TSA) and dual polarization interferometry (DPI)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grøftehauge, Morten K., E-mail: m.k.groftehauge@durham.ac.uk; Hajizadeh, Nelly R.; Swann, Marcus J.

2015-01-01

The biophysical characterization of protein–ligand interactions in solution using techniques such as thermal shift assay, or on surfaces using, for example, dual polarization interferometry, plays an increasingly important role in complementing crystal structure determinations. Over the last decades, a wide range of biophysical techniques investigating protein–ligand interactions have become indispensable tools to complement high-resolution crystal structure determinations. Current approaches in solution range from high-throughput-capable methods such as thermal shift assays (TSA) to highly accurate techniques including microscale thermophoresis (MST) and isothermal titration calorimetry (ITC) that can provide a full thermodynamic description of binding events. Surface-based methods such as surface plasmonmore » resonance (SPR) and dual polarization interferometry (DPI) allow real-time measurements and can provide kinetic parameters as well as binding constants. DPI provides additional spatial information about the binding event. Here, an account is presented of new developments and recent applications of TSA and DPI connected to crystallography.« less

An Experimental Weight Function Method for Stress Intensity Factor Calibration.

DTIC Science & Technology

1980-04-01

in accuracy to the ones obtained by Macha (Reference 10) for the laser interferometry technique. The values of KI from the interpolating polynomial...Measurement. Air Force Material Laboratories, AFML-TR-74-75, July 1974. 10. D. E. Macha , W. N. Sharpe Jr., and A. F. Grandt Jr., A Laser Interferometry

Development of phase detection schemes based on surface plasmon resonance using interferometry.

PubMed

Kashif, Muhammad; Bakar, Ahmad Ashrif A; Arsad, Norhana; Shaari, Sahbudin

2014-08-28

Surface plasmon resonance (SPR) is a novel optical sensing technique with a unique ability to monitor molecular binding in real-time for biological and chemical sensor applications. Interferometry is an excellent tool for accurate measurement of SPR changes, the measurement and comparison is made for the sensitivity, dynamic range and resolution of the different analytes using interferometry techniques. SPR interferometry can also employ phase detection in addition to the amplitude of the reflected light wave, and the phase changes more rapidly compared with other approaches, i.e., intensity, angle and wavelength. Therefore, the SPR phase interferometer offers the advantages of spatial phase resolution and high sensitivity. This work discusses the advancements in interferometric SPR methods to measure the phase shifts due to refractive index changes. The main application areas of SPR sensors are demonstrated, i.e., the Fabry-Perot interferometer, Michelson interferometer and Mach-Zehnder interferometer, with different configurations. The three interferometers are discussed in detail, and solutions are suggested to enhance the performance parameters that will aid in future biological and chemical sensors.

Development of Phase Detection Schemes Based on Surface Plasmon Resonance Using Interferometry

PubMed Central

Kashif, Muhammad; Bakar, Ahmad Ashrif A.; Arsad, Norhana; Shaari, Sahbudin

2014-01-01

Surface plasmon resonance (SPR) is a novel optical sensing technique with a unique ability to monitor molecular binding in real-time for biological and chemical sensor applications. Interferometry is an excellent tool for accurate measurement of SPR changes, the measurement and comparison is made for the sensitivity, dynamic range and resolution of the different analytes using interferometry techniques. SPR interferometry can also employ phase detection in addition to the amplitude of the reflected light wave, and the phase changes more rapidly compared with other approaches, i.e., intensity, angle and wavelength. Therefore, the SPR phase interferometer offers the advantages of spatial phase resolution and high sensitivity. This work discusses the advancements in interferometric SPR methods to measure the phase shifts due to refractive index changes. The main application areas of SPR sensors are demonstrated, i.e., the Fabry-Perot interferometer, Michelson interferometer and Mach-Zehnder interferometer, with different configurations. The three interferometers are discussed in detail, and solutions are suggested to enhance the performance parameters that will aid in future biological and chemical sensors. PMID:25171117

Quasiperiodic moiré plasmonic crystals.

PubMed

Lubin, Steven M; Hryn, Alexander J; Huntington, Mark D; Engel, Clifford J; Odom, Teri W

2013-12-23

This paper describes the properties of silver plasmonic crystals with quasiperiodic rotational symmetries. Compared to periodic plasmonic crystals, quasiperiodic moiré structures exhibited an increased number of surface plasmon polariton modes, especially at high angles of excitation. In addition, plasmonic band gaps were often formed at the intersections of these new modes. To identify the origin and predict the location of the band gaps, we developed a Bragg-based indexing system using the reciprocal lattice vectors of the moiré plasmonic crystals. We showed that even more complicated quasiperiodic geometries could also be described by this indexing model. We anticipate that these quasiperiodic lattices will be useful for applications that require the concentration and manipulation of light over a broadband spectrum.

Op art and visual perception.

PubMed

Wade, N J

1978-01-01

An attempt is made to list the visual phenomena exploited in op art. These include moire frinlude moiré fringes, afterimages, Hermann grid effects, Gestalt grouping principles, blurring and movement due to astigmatic fluctuations in accommodation, scintillation and streaming possibly due to eye movements, and visual persistence. The historical origins of these phenomena are also noted.

Real-time analysis keratometer

NASA Technical Reports Server (NTRS)

Adachi, Iwao P. (Inventor); Adachi, Yoshifumi (Inventor); Frazer, Robert E. (Inventor)

1987-01-01

A computer assisted keratometer in which a fiducial line pattern reticle illuminated by CW or pulsed laser light is projected on a corneal surface through lenses, a prismoidal beamsplitter quarterwave plate, and objective optics. The reticle surface is curved as a conjugate of an ideal corneal curvature. The fiducial image reflected from the cornea undergoes a polarization shift through the quarterwave plate and beamsplitter whereby the projected and reflected beams are separated and directed orthogonally. The reflected beam fiducial pattern forms a moire pattern with a replica of the first recticle. This moire pattern contains transverse aberration due to differences in curvature between the cornea and the ideal corneal curvature. The moire pattern is analyzed in real time by computer which displays either the CW moire pattern or a pulsed mode analysis of the transverse aberration of the cornea under observation, in real time. With the eye focused on a plurality of fixation points in succession, a survey of the entire corneal topography is made and a contour map or three dimensional plot of the cornea can be made as a computer readout in addition to corneal radius and refractive power analysis.

Theory of optical absorption by interlayer excitons in transition metal dichalcogenide heterobilayers

DOE PAGES

Wu, Fengcheng; Lovorn, Timothy; MacDonald, A. H.

2018-01-22

In this paper, we present a theory of optical absorption by interlayer excitons in a heterobilayer formed from transition metal dichalcogenides. The theory accounts for the presence of small relative rotations that produce a momentum shift between electron and hole bands located in different layers, and a moire pattern in real space. Because of the momentum shift, the optically active interlayer excitons are located at the moire Brillouin zone's corners, instead of at its center, and would have elliptical optical selection rules if the individual layers were translationally invariant. We show that the exciton moire potential energy restores circular opticalmore » selection rules by coupling excitons with different center of mass momenta. A variety of interlayer excitons with both senses of circular optical activity, and energies that are tunable by twist angle, are present at each valley. The lowest energy exciton states are generally localized near the exciton potential energy minima. Finally, we discuss the possibility of using the moire pattern to achieve scalable two-dimensional arrays of nearly identical quantum dots.« less

Using the graphene Moiré pattern for the trapping of C60 and homoepitaxy of graphene.

PubMed

Lu, Jiong; Yeo, Pei Shan Emmeline; Zheng, Yi; Yang, Zhiyong; Bao, Qiaoliang; Gan, Chee Kwan; Loh, Kian Ping

2012-01-24

The graphene Moiré superstructure offers a complex landscape of humps and valleys to molecules adsorbing and diffusing on it. Using C(60) molecules as the classic hard sphere analogue, we examine its assembly and layered growth on this corrugated landscape. At the monolayer level, the cohesive interactions of C(60) molecules adsorbing on the Moiré lattice freeze the molecular rotation of C(60) trapped in the valley sites, resulting in molecular alignment of all similarly trapped C(60) molecules at room temperature. The hierarchy of adsorption potential well on the Moiré lattice causes diffusion-limited dendritic growth of C(60) films, as opposed to isotropic growth observed on a smooth surface like graphite. Due to the strong binding energy of the C(60) film, part of the dentritic C(60) films polymerize at 850 K and act as solid carbon sources for graphene homoepitaxy. Our findings point to the possibility of using periodically corrugated graphene in molecular spintronics due to its ability to trap and align organic molecules at room temperature. © 2011 American Chemical Society

Theory of optical absorption by interlayer excitons in transition metal dichalcogenide heterobilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Fengcheng; Lovorn, Timothy; MacDonald, A. H.

In this paper, we present a theory of optical absorption by interlayer excitons in a heterobilayer formed from transition metal dichalcogenides. The theory accounts for the presence of small relative rotations that produce a momentum shift between electron and hole bands located in different layers, and a moire pattern in real space. Because of the momentum shift, the optically active interlayer excitons are located at the moire Brillouin zone's corners, instead of at its center, and would have elliptical optical selection rules if the individual layers were translationally invariant. We show that the exciton moire potential energy restores circular opticalmore » selection rules by coupling excitons with different center of mass momenta. A variety of interlayer excitons with both senses of circular optical activity, and energies that are tunable by twist angle, are present at each valley. The lowest energy exciton states are generally localized near the exciton potential energy minima. Finally, we discuss the possibility of using the moire pattern to achieve scalable two-dimensional arrays of nearly identical quantum dots.« less

Digitally enhanced homodyne interferometry.

PubMed

Sutton, Andrew J; Gerberding, Oliver; Heinzel, Gerhard; Shaddock, Daniel A

2012-09-24

We present two variations of a novel interferometry technique capable of simultaneously measuring multiple targets with high sensitivity. The technique performs a homodyne phase measurement by application of a four point phase shifting algorithm, with pseudo-random switching between points to allow multiplexed measurement based upon propagation delay alone. By multiplexing measurements and shifting complexity into signal processing, both variants realise significant complexity reductions over comparable methods. The first variant performs a typical coherent detection with a dedicated reference field and achieves a displacement noise floor 0.8 pm/√Hz above 50 Hz. The second allows for removal of the dedicated reference, resulting in further simplifications and improved low frequency performance with a 1 pm/√Hz noise floor measured down to 20 Hz. These results represent the most sensitive measurement performed using this style of interferometry whilst simultaneously reducing the electro-optic footprint.

Electro-Optical Inspection For Tolerance Control As An Integral Part Of A Flexible Machining Cell

NASA Astrophysics Data System (ADS)

Renaud, Blaise

1986-11-01

Institut CERAC has been involved in optical metrology and 3-dimensional surface control for the last couple of years. Among the industrial applications considered is the on-line shape evaluation of machined parts within the manufacturing cell. The specific objective is to measure the machining errors and to compare them with the tolerances set by designers. An electro-optical sensing technique has been developed which relies on a projection Moire contouring optical method. A prototype inspection system has been designed, making use of video detection and computer image processing. Moire interferograms are interpreted, and the metrological information automatically retrieved. A structured database can be generated for subsequent data analysis and for real-time closed-loop corrective actions. A real-time kernel embedded into a synchronisation network (Petri-net) for the control of concurrent processes in the Electra-Optical Inspection (E0I) station was realised and implemented in a MODULA-2 program DIN01. The prototype system for on-line automatic tolerance control taking place within a flexible machining cell is described in this paper, together with the fast-prototype synchronisation program.

Automated Reduction of Data from Images and Holograms

NASA Technical Reports Server (NTRS)

Lee, G. (Editor); Trolinger, James D. (Editor); Yu, Y. H. (Editor)

1987-01-01

Laser techniques are widely used for the diagnostics of aerodynamic flow and particle fields. The storage capability of holograms has made this technique an even more powerful. Over 60 researchers in the field of holography, particle sizing and image processing convened to discuss these topics. The research program of ten government laboratories, several universities, industry and foreign countries were presented. A number of papers on holographic interferometry with applications to fluid mechanics were given. Several papers on combustion and particle sizing, speckle velocimetry and speckle interferometry were given. A session on image processing and automated fringe data reduction techniques and the type of facilities for fringe reduction was held.

Astronomical Optical Interferometry. I. Methods and Instrumentation

NASA Astrophysics Data System (ADS)

Jankov, S.

2010-12-01

Previous decade has seen an achievement of large interferometric projects including 8-10m telescopes and 100m class baselines. Modern computer and control technology has enabled the interferometric combination of light from separate telescopes also in the visible and infrared regimes. Imaging with milli-arcsecond (mas) resolution and astrometry with micro-arcsecond (muas) precision have thus become reality. Here, I review the methods and instrumentation corresponding to the current state in the field of astronomical optical interferometry. First, this review summarizes the development from the pioneering works of Fizeau and Michelson. Next, the fundamental observables are described, followed by the discussion of the basic design principles of modern interferometers. The basic interferometric techniques such as speckle and aperture masking interferometry, aperture synthesis and nulling interferometry are disscused as well. Using the experience of past and existing facilities to illustrate important points, I consider particularly the new generation of large interferometers that has been recently commissioned (most notably, the CHARA, Keck, VLT and LBT Interferometers). Finally, I discuss the longer-term future of optical interferometry, including the possibilities of new large-scale ground-based projects and prospects for space interferometry.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 onmore » 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.« less

Radio interferometry: Techniques for Geodesy. [conference

NASA Technical Reports Server (NTRS)

1980-01-01

Progress in the development and application of radio interferometry as a tool for geophysical research is reported and discussed. Among the topics reviewed are: Surveys of is the Seventies, Movements, Terrestrial and Celestial, Degrees Kelvin and Degrees of Phase, the Mark 3 VLBI System, Waves of the Future and other Emissions, and Adherence and Coherence in Networks, and Plans.

Denoising in digital speckle pattern interferometry using wave atoms.

PubMed

Federico, Alejandro; Kaufmann, Guillermo H

2007-05-15

We present an effective method for speckle noise removal in digital speckle pattern interferometry, which is based on a wave-atom thresholding technique. Wave atoms are a variant of 2D wavelet packets with a parabolic scaling relation and improve the sparse representation of fringe patterns when compared with traditional expansions. The performance of the denoising method is analyzed by using computer-simulated fringes, and the results are compared with those produced by wavelet and curvelet thresholding techniques. An application of the proposed method to reduce speckle noise in experimental data is also presented.

Tone-assisted time delay interferometry on GRACE Follow-On

NASA Astrophysics Data System (ADS)

Francis, Samuel P.; Shaddock, Daniel A.; Sutton, Andrew J.; de Vine, Glenn; Ware, Brent; Spero, Robert E.; Klipstein, William M.; McKenzie, Kirk

2015-07-01

We have demonstrated the viability of using the Laser Ranging Interferometer on the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) space mission to test key aspects of the interspacecraft interferometry proposed for detecting gravitational waves. The Laser Ranging Interferometer on GRACE-FO will be the first demonstration of interspacecraft interferometry. GRACE-FO shares many similarities with proposed space-based gravitational wave detectors based on the Laser Interferometer Space Antenna (LISA) concept. Given these similarities, GRACE-FO provides a unique opportunity to test novel interspacecraft interferometry techniques that a LISA-like mission will use. The LISA Experience from GRACE-FO Optical Payload (LEGOP) is a project developing tests of arm locking and time delay interferometry (TDI), two frequency stabilization techniques, that could be performed on GRACE-FO. In the proposed LEGOP TDI demonstration one GRACE-FO spacecraft will have a free-running laser while the laser on the other spacecraft will be locked to a cavity. It is proposed that two one-way interspacecraft phase measurements will be combined with an appropriate delay in order to produce a round-trip, dual one-way ranging (DOWR) measurement independent of the frequency noise of the free-running laser. This paper describes simulated and experimental tests of a tone-assisted TDI ranging (TDIR) technique that uses a least-squares fitting algorithm and fractional-delay interpolation to find and implement the delays needed to form the DOWR TDI combination. The simulation verifies tone-assisted TDIR works under GRACE-FO conditions. Using simulated GRACE-FO signals the tone-assisted TDIR algorithm estimates the time-varying interspacecraft range with a rms error of ±0.2 m , suppressing the free-running laser frequency noise by 8 orders of magnitude. The experimental results demonstrate the practicability of the technique, measuring the delay at the 6 ns level in the presence of a significant displacement signal.

Holographic Moire Contouring

NASA Astrophysics Data System (ADS)

Sciammarella, C. A.; Sainov, Ventseslav; Simova, Eli

1990-04-01

Theoretical analysis and experimental results on holographic moire contouring (HMC) of difussely reflecting objects are presented. The sensitivity and application constraints of the method are discussed. A high signal-to-noise ratio and contrast of the fringes is achieved through the use of high quality silver halide holographic plates HP-650. A good agreement between theoretical and experimental results is observed.

Angle-resolved low-coherence interferometry: an optical biopsy technique for clinical detection of dysplasia in Barrett’s esophagus

PubMed Central

Zhu, Yizheng; Terry, Neil G; Wax, Adam

2012-01-01

Angle-resolved low-coherence interferometry (a/LCI) is an optical biopsy technique that measures scattered light from tissue to determine nuclear size with submicron-level accuracy. The a/LCI probe can be deployed through the accessory channel of a standard endoscope and provides feedback to physicians to guide physical biopsies. The technique has been validated in animal and ex vivo human studies, and has been used to detect dysplasia in Barrett’s esophagus patients in vivo. In a recent clinical study of 46 Barrett’s esophagus patients, a/LCI was able to detect dysplasia with 100% sensitivity and 84% specificity. This report reviews the technique and discusses its potential clinical utility. PMID:22149580

Spin and charge transport through 1D Moire Crystals

NASA Astrophysics Data System (ADS)

Barraud, Clement; Bonnet, Romeo; Martin, Pascal; Della Rocca, Maria Luisa; Lafarge, Philippe; Laboratoire Matériaux Et Phénomènes Quantiques Team; Laboratoire Itodys Team

Multiwall carbon nanotubes are good candidates for propagating spin information over large distances due to the large mobility of the carriers and to the weak spin-orbit coupling and hyperfine interactions. In this talk, I will present an experimental study concerning charge and spin transport through large diameter multiwall carbon nanotubes presenting intershell interactions leading to superlattice effects (1D Moire). After a description of 1D Moire crystals and to the implication of such superlattices in quantum transport, I will show that spin transport seems to be very efficient close to the new van Hove singularities. Clear magnetoresistance signals of the order of 40 % are reported at low temperatures. We acknowledge financial supports from the Labex SEAM and DIM NANO-K.

The Beauty and Limitations of 10 Micron Heterodyne Interferometry (ISI)

NASA Technical Reports Server (NTRS)

Danchi, William C.

2003-01-01

Until recently, heterodyne interferometry at 10 microns has been the only successful technique for stellar interferometry in the very difficult atmospheric window from 9-12 microns. For most of its operational lifetime the U.C. Berkeley Infrared Spatial Interferometer was a single-baseline two telescope (1.65 m aperture) system using CO2 lasers as local oscillators. This instrument was designed and constructed from 1983-1988, and first fringes were obtained at Mt. Wilson in June 1988. During the past few years, a third telescope was constructed and just recently the first closure phases were obtained at 11.15 microns. We discuss the history, physics and technology of heterodyne interferometry in the mid-infrared, and some key astronomical results that have come from this unique instrument.

Advanced subsidence monitoring using persistent scatterer interferometry for Jharia Coal Field, Dhanbad, India

NASA Astrophysics Data System (ADS)

Thapa, Shailaja; Chatterjee, R. S.; Kumar, Dheeraj; Singh, K. B.; Sengar, Vivek

2017-10-01

This paper presents a spatiotemporal study of surface subsidence over urban area due to coal mining using Persistent scatterer interferometry. In the past few years Differential Interferometric Synthetic Aperture Radar has emerged as a very useful remote sensing technique for measuring land subsidence. It plays a vital role in insitu subsidence prediction of coal mining area. However there are some limitation viz. atmospheric decorrelation, temporal decorrelation and spatial decorrelation with conventional D-InSAR techniques, which can be overcome up to certain extent by using multiinterferogram framework approach. The Persistent Scatterer interferometry technique comprises of more number of SAR datasets, it only concentrates over the pixel which remain coherent over long time period. Persistent Scatterer interferometry makes deformation measurement on permanent scattering location for the targeted ground surface. Mainly, these permanent scatterer are manmade features like metallic bridges, dams, antennae roof of buildings etc. apart that some permanent scatterer may comprise of prominent stable natural targets. The results obtained from PS-InSAR gives more precised measurement of surface deformation. Total eight ALOS PALSAR scenes covering the time period from 2007 to 2010 have been utilized to produce ground deformation map using PSInSAR techniques for Jharia Coal field, Dhanbad. This is proven technique, which helps to identify the persistent land surface movement .The results were analyzed Sijua area in Jharia coalfield. The subsidence fringes were demarcated over the entire study area. The PSInSAR results were validated using precision leveling data provided by mining authorities. The results demonstrates that PSInSAR can be used as potential tool to highlight the subsidence prone area depending upon the spatial and temporal coherency of SAR data.

Global astrometry with the space interferometry mission

NASA Technical Reports Server (NTRS)

Boden, A.; Unwin, S.; Shao, M.

1997-01-01

The prospects for global astrometric measurements with the space interferometry mission (SIM) are discussed. The SIM mission will perform four microarcsec astrometric measurements on objects as faint as 20 mag using the optical interferometry technique with a 10 m baseline. The SIM satellite will perform narrow angle astrometry and global astrometry by means of an astrometric grid. The sensitivities of the SIM global astrometric performance and the grid accuracy versus instrumental parameters and sky coverage schemes are reported on. The problems in finding suitable astrometric grid objects to support microarcsec astrometry, and related ground-based observation programs are discussed.

Sentinel-1 TOPS interferometry for along-track displacement measurement

NASA Astrophysics Data System (ADS)

Jiang, H. J.; Pei, Y. Y.; Li, J.

2017-02-01

The European Space Agency’s Sentinel-1 mission, a constellation of two C-band synthetic aperture radar (SAR) satellites, utilizes terrain observation by progressive scan (TOPS) antenna beam steering as its default operation mode to achieve wide-swath coverage and short revisit time. The beam steering during the TOPS acquisition provides a means to measure azimuth motion by using the phase difference between forward and backward looking interferograms within regions of burst overlap. Hence, there are two spectral diversity techniques for along-track displacement measurement, including multi-aperture interferometry (MAI) and “burst overlap interferometry”. This paper analyses the measurement accuracies of MAI and burst overlap interferometry. Due to large spectral separation in the overlap region, burst overlap interferometry is a more sensitive measurement. We present a TOPS interferometry approach for along-track displacement measurement. The phase bias caused by azimuth miscoregistration is first estimated by burst overlap interferometry over stationary regions. After correcting the coregistration error, the MAI phase and the interferometric phase difference between burst overlaps are recalculated to obtain along-track displacements. We test the approach with Sentinel-1 TOPS interferometric data over the 2015 Mw 7.8 Nepal earthquake fault. The results prove the feasibility of our approach and show the potential of joint estimation of along-track displacement with burst overlap interferometry and MAI.

X-ray grating interferometry at photon energies over 180 keV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruiz-Yaniz, M., E-mail: maite.ruiz-yaniz@esrf.fr; Lehrstuhl für Biomedizinische Physik, Physik-Department and Institut für Medizintechnik, Technische Universität München, James-Franck-Str. 1, 85748 Garching; Koch, F.

2015-04-13

We report on the implementation and characterization of grating interferometry operating at an x-ray energy of 183 keV. With the possibility to use this technique at high x-ray energies, bigger specimens could be studied in a quantitative way. Also, imaging strongly absorbing specimens will benefit from the advantages of the phase and dark-field signals provided by grating interferometry. However, especially at these high photon energies the performance of the absorption grating becomes a key point on the quality of the system, because the grating lines need to keep their small width of a couple of micrometers and exhibit a greater heightmore » of hundreds of micrometers. The performance of high aspect ratio absorption gratings fabricated with different techniques is discussed. Further, a dark-field image of an alkaline multicell battery highlights the potential of high energy x-ray grating based imaging.« less

A decade of innovation with laser speckle metrology

NASA Astrophysics Data System (ADS)

Ettemeyer, Andreas

2003-05-01

Speckle Pattern Interferometry has emerged from the experimental substitution of holographic interferometry to become a powerful problem solving tool in research and industry. The rapid development of computer and digital imaging techniques in combination with minaturization of the optical equipment led to new applications which had not been anticipated before. While classical holographic interferometry had always required careful consideration of the environmental conditions such as vibration, noise, light, etc. and could generally only be performed in the optical laboratory, it is now state of the art, to handle portable speckle measuring equipment at almost any place. During the last decade, the change in design and technique has dramatically influenced the range of applications of speckle metrology and opened new markets. The integration of recent research results into speckle measuring equipment has led to handy equipment, simplified the operation and created high quality data output.

Dispersion-cancelled biological imaging with quantum-inspired interferometry

PubMed Central

Mazurek, M. D.; Schreiter, K. M.; Prevedel, R.; Kaltenbaek, R.; Resch, K. J.

2013-01-01

Quantum information science promises transformative impact over a range of key technologies in computing, communication, and sensing. A prominent example uses entangled photons to overcome the resolution-degrading effects of dispersion in the medical-imaging technology, optical coherence tomography. The quantum solution introduces new challenges: inherently low signal and artifacts, additional unwanted signal features. It has recently been shown that entanglement is not a requirement for automatic dispersion cancellation. Such classical techniques could solve the low-signal problem, however they all still suffer from artifacts. Here, we introduce a method of chirped-pulse interferometry based on shaped laser pulses, and use it to produce artifact-free, high-resolution, dispersion-cancelled images of the internal structure of a biological sample. Our work fulfills one of the promises of quantum technologies: automatic-dispersion-cancellation interferometry in biomedical imaging. It also shows how subtle differences between a quantum technique and its classical analogue may have unforeseen, yet beneficial, consequences. PMID:23545597

Grounding line migration of Petermann Gletscher, north Greenland, detected using satellite radar interferometry

NASA Technical Reports Server (NTRS)

Rignot, Eric

1997-01-01

Ice Sheet grounding lines are sensitive indicator of changes in ice thickness, sea level or elevation of the sea bed. Here, we use the synthetic-aperture radar interferometry technique to detect the migration of thel imit of tidal flexing, or hinge line, of Petermann Gletscher, a major outlet glacier of north Greenland which develops an extensive floating tongue.

Spatial heterodyne interferometry of VY Canis Major's, alpha Orionis, alpha Scorpii, and R leonis at 11 microns

NASA Technical Reports Server (NTRS)

Sutton, E. C.; Storey, J. W. V.; Betz, A. L.; Townes, C. H.; Spears, D. L.

1977-01-01

Using the technique of heterodyne interferometry, measurements were made of the spatial distribution of 11 micron radiation from four late type stars. The circumstellar shells surrounding VY Canis Majoris, alpha Orionis, and alpha Scorpii were resolved, whereas that of R Leonis was only partially resolved at a fringe spacing of 0.4 sec.

A low cost method for hard x-ray grating interferometry.

PubMed

Du, Yang; Lei, Yaohu; Liu, Xin; Huang, Jianheng; Zhao, Zhigang; Guo, Jinchuan; Li, Ji; Niu, Hanben

2016-12-07

Grating interferometry is advantageous over conventional x-ray absorption imaging because it enables the detection of samples constituted by low atomic number elements (low-Z materials). Therefore, it has a potential application in biological science and medical diagnostics. The grating interferometry has some critical optics components such as absorption gratings which are conventionally manufactured by the lithography, electroplating, and molding (LIGA) technique and employing gold as the absorbent material in it. However, great challenge lies in its implementations for practical applications because of the cost and difficulty to achieve high aspect ratio absorbing grating devices. In this paper, we present a low-cost approach that involves using the micro-casting technique with bismuth (Bi) as the absorber in source grating and as well as filling cesium iodide thallium(CsI:Tl) in a periodically structured scintillator. No costly facilities as synchrotron radiation are required and cheap material is used in our approach. Our experiment using these components shows high quality complementary images can be obtained with contrast of absorption, phase and visibility. This alternative method conquers the limitation of costly grating devices for a long time and stands an important step towards the further practical application of grating interferometry.

Dual-hologram shearing interference technique with regulated sensitivity

NASA Astrophysics Data System (ADS)

Toker, Gregory R.; Levin, Daniel

1998-06-01

A novel optical diagnostic technique,namely, a dual hologram shearing interferometry with regulated sensitivity, is proposed for visualization and measuring the density gradients of compressible flows in wind tunnels. It has advantages over conventional shearing interferometry in both accuracy and sensitivity. The method is especially useful for strong turbulent or unsteady regions of the flows including shock flows. The interferometer proved to be insensitive to mechanical vibrations and allowed to record holograms during the noisy wind tunnel run. The proposed approach was demonstrated by its application to a supersonic flow over spherically blunted and sharp nose cone/cylinder models. It is believed that the technique will become an effective tool for receiving optical data in many flow facilities.

Microinterferometric optical phase tomography for measuring small, asymmetric refractive-index differences in the profiles of optical fibers and fiber devices.

PubMed

Bachim, Brent L; Gaylord, Thomas K

2005-01-20

A new technique, microinterferometric optical phase tomography, is introduced for use in measuring small, asymmetric refractive-index differences in the profiles of optical fibers and fiber devices. The method combines microscopy-based fringe-field interferometry with parallel projection-based computed tomography to characterize fiber index profiles. The theory relating interference measurements to the projection set required for tomographic reconstruction is given, and discrete numerical simulations are presented for three test index profiles that establish the technique's ability to characterize fiber with small, asymmetric index differences. An experimental measurement configuration and specific interferometry and tomography practices employed in the technique are discussed.

Cement paste surface roughness analysis using coherence scanning interferometry and confocal microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Apedo, K.L., E-mail: apedo@unistra.fr; Munzer, C.; He, H.

2015-02-15

Scanning electron microscopy and scanning probe microscopy have been used for several decades to better understand the microstructure of cementitious materials. Very limited work has been performed to date to study the roughness of cementitious materials by optical microscopy such as coherence scanning interferometry (CSI) and chromatic confocal sensing (CCS). The objective of this paper is to better understand how CSI can be used as a tool to analyze surface roughness and topography of cement pastes. Observations from a series of images acquired using this technique on both polished and unpolished samples are described. The results from CSI are comparedmore » with those from a STIL confocal microscopy technique (SCM). Comparison between both optical techniques demonstrates the ability of CSI to measure both polished and unpolished cement pastes. - Highlights: • Coherence scanning interferometry (CSI) was used to analyze cement paste surfaces. • The results from the CSI were compared with those from a confocal microscopy. • 3D roughness parameters were obtained using the window resizing method. • Polished and unpolished cement pastes were studied.« less

Moiré edge states in twisted graphene nanoribbons

NASA Astrophysics Data System (ADS)

Fleischmann, M.; Gupta, R.; Weckbecker, D.; Landgraf, W.; Pankratov, O.; Meded, V.; Shallcross, S.

2018-05-01

The edge physics of graphene based systems is well known to be highly sensitive to the atomic structure at the boundary, with localized zero mode edge states found only on the zigzag-type termination of the lattice. Here we demonstrate that the graphene twist bilayer supports an additional class of edge states, that (i) are found for all edge geometries and thus are robust against edge roughness, (ii) occur at energies coinciding with twist induced Van Hove singularities in the bulk and (iii) possess an electron density strongly modulated by the moiré lattice. Interestingly, these "moiré edge states" exist only for certain lattice commensurations and thus the edge physics of the twist bilayer is, in dramatic contrast to that of the bulk, not uniquely determined by the twist angle.

Fringe-shifting single-projector moiré topography application for cotyle implantate abrasion measurement

NASA Astrophysics Data System (ADS)

Rössler, Tomáš; Hrabovský, Miroslav; Pluháček, František

2005-08-01

The cotyle implantate is abraded in the body of patient and its shape changes. Information about the magnitude of abrasion is contained in the result contour map of the implantate. The locations and dimensions of abraded areas can be computed from the contours deformation. The method called the single-projector moire topography was used for the contour lines determination. The theoretical description of method is given at first. The design of the experimental set-up follows. The light grating projector was developed to realize the periodic structure on the measured surface. The method of fringe-shifting was carried out to increase the data quantity. The description of digital processing applied to the moire grating images is introduced at the end together with the examples of processed images.

Experimental evidence of the spatial coherence moiré and the filtering of classes of radiator pairs.

PubMed

Castaneda, Roman; Usuga-Castaneda, Mario; Herrera-Ramírez, Jorge

2007-08-01

Evidence of the physical existence of the spatial coherence moiré is obtained by confronting numerical results with experimental results of spatially partial interference. Although it was performed for two particular cases, the results reveal a general behavior of the optical fields in any state of spatial coherence. Moreover, the study of the spatial coherence moiré deals with a new type of filtering, named filtering of classes of radiator pairs, which allows changing the power spectrum at the observation plane by modulating the complex degree of spatial coherence, without altering the power distribution at the aperture plane or introducing conventional spatial filters. This new procedure can optimize some technological applications of actual interest, as the beam shaping for instance.

Encoder fault analysis system based on Moire fringe error signal

NASA Astrophysics Data System (ADS)

Gao, Xu; Chen, Wei; Wan, Qiu-hua; Lu, Xin-ran; Xie, Chun-yu

2018-02-01

Aiming at the problem of any fault and wrong code in the practical application of photoelectric shaft encoder, a fast and accurate encoder fault analysis system is researched from the aspect of Moire fringe photoelectric signal processing. DSP28335 is selected as the core processor and high speed serial A/D converter acquisition card is used. And temperature measuring circuit using AD7420 is designed. Discrete data of Moire fringe error signal is collected at different temperatures and it is sent to the host computer through wireless transmission. The error signal quality index and fault type is displayed on the host computer based on the error signal identification method. The error signal quality can be used to diagnosis the state of error code through the human-machine interface.

Satellite radar interferometry measures deformation at Okmok Volcano

USGS Publications Warehouse

Lu, Zhong; Mann, Dorte; Freymueller, Jeff

1998-01-01

The center of the Okmok caldera in Alaska subsided 140 cm as a result of its February– April 1997 eruption, according to satellite data from ERS-1 and ERS-2 synthetic aperture radar (SAR) interferometry. The inferred deflationary source was located 2.7 km beneath the approximate center of the caldera using a point source deflation model. Researchers believe this source is a magma chamber about 5 km from the eruptive source vent. During the 3 years before the eruption, the center of the caldera uplifted by about 23 cm, which researchers believe was a pre-emptive inflation of the magma chamber. Scientists say such measurements demonstrate that radar interferometry is a promising spaceborne technique for monitoring remote volcanoes. Frequent, routine acquisition of images with SAR interferometry could make near realtime monitoring at such volcanoes the rule, aiding in eruption forecasting.

Mapping small elevation changes over large areas - Differential radar interferometry

NASA Technical Reports Server (NTRS)

Gabriel, Andrew K.; Goldstein, Richard M.; Zebker, Howard A.

1989-01-01

A technique is described, based on synthetic aperture radar (SAR) interferometry, which uses SAR images for measuring very small (1 cm or less) surface motions with good resolution (10 m) over swaths of up to 50 km. The method was applied to a Seasat data set of an imaging site in Imperial Valley, California, where motion effects were observed that were identified with movements due to the expansion of water-absorbing clays. The technique can be used for accurate measurements of many geophysical phenomena, including swelling and buckling in fault zones, residual displacements from seismic events, and prevolcanic swelling.

Optical fiber Fabry-Perot interferometry

NASA Astrophysics Data System (ADS)

Wang, Anbo

2014-06-01

Fiber Fabry-Perot (FP) interferometry is one of the most important tools for harsh environment sensing because of its great flexibility of sensor material selection, superior long-­-term stability, and nature of remote passive operation. Virginia Tech's Center for Photonics Technology has been involved in the research of this field for many years. After a quick review of the typical methods for the construction of F-P sensors, emphasis will be placed on the whitelight interferometry, which is perhaps the most robust interferometric sensor demodulation technique today. The recent discovery of an additional phase will be presented and its significance to the sensor demodulation will be discussed.

Compact portable diffraction moire interferometer

DOEpatents

Deason, Vance A.; Ward, Michael B.

1989-01-01

A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observation means including film and video cameras may be used to view and record the resultant fringe patterns.

Approche structurée en pratique familiale pour les patients ayant des problèmes de mémoire

PubMed Central

Lee, Linda; Weston, W. Wayne; Heckman, George; Gagnon, Micheline; Lee, F. Joseph; Sloka, Scott

2013-01-01

Résumé Objectif Présenter aux médecins de famille une approche structurée pour les patients qui présentent des problèmes de mémoire. Sources des données Cette approche se fonde sur un programme agréé de formation clinique sur la mémoire, élaboré par le Centre for Family Medicine Memory Clinic en partenariat avec le Collège des médecins de famille de l’Ontario. Message principal Le recours à une approche structurée de raisonnement clinique peut aider les médecins à poser un diagnostic exact chez des patients qui présentent des problèmes de mémoire. Le délirium, la dépression et les causes réversibles doivent être exclus, pour ensuite faire une différenciation entre le vieillissement cognitif normal, la déficience cognitive légère et la démence. Il est essentiel de procéder à une anamnèse collatérale et à une évaluation fonctionnelle exacte. Les formes courantes de la démence peuvent être cliniquement différenciées par la séquence dans laquelle les symptômes apparaissent et par la façon dont les déficits cognitifs évoluent avec le temps. Habituellement, les signes précoces de la démence d’Alzheimer comportent une déficience de la mémoire épisodique, tandis que la démence due principalement à des causes vasculaires peut se présenter par une perte précoce de la fonction exécutive et de la fonction visuospatiale, ainsi que des caractéristiques cliniques particulières. Conclusion Une approche de raisonnement clinique peut aider les médecins à poser des diagnostics précoces et exacts qui peuvent orienter une prise en charge appropriée et améliorer les soins aux patients qui ont des problèmes de mémoire.

Combined dispersive/interference spectroscopy for producing a vector spectrum

DOEpatents

Erskine, David J.

2002-01-01

A method of measuring the spectral properties of broadband waves that combines interferometry with a wavelength disperser having many spectral channels to produce a fringing spectrum. Spectral mapping, Doppler shifts, metrology of angles, distances and secondary effects such as temperature, pressure, and acceleration which change an interferometer cavity length can be measured accurately by a compact instrument using broadband illumination. Broadband illumination avoids the fringe skip ambiguities of monochromatic waves. The interferometer provides arbitrarily high spectral resolution, simple instrument response, compactness, low cost, high field of view and high efficiency. The inclusion of a disperser increases fringe visibility and signal to noise ratio over an interferometer used alone for broadband waves. The fringing spectrum is represented as a wavelength dependent 2-d vector, which describes the fringe amplitude and phase. Vector mathematics such as generalized dot products rapidly computes average broadband phase shifts to high accuracy. A Moire effect between the interferometer's sinusoidal transmission and the illumination heterodynes high resolution spectral detail to low spectral detail, allowing the use of a low resolution disperser. Multiple parallel interferometer cavities of fixed delay allow the instantaneous mapping of a spectrum, with an instrument more compact for the same spectral resolution than a conventional dispersive spectrometer, and not requiring a scanning delay.

Measurement of strain distribution in bonded joints by fiber Bragg gratings

NASA Astrophysics Data System (ADS)

Guemes, J. Alfredo; Diaz-Carrillo, Sebastian; Menendez, Jose M.

1998-07-01

Due to the small dimensions of the adhesive layer, the high non-uniformity of the strain field and the non linear elastic behavior of the adhesive material, the strain distribution at an adhesive joint can be predicted by FEM, but can not be experimentally obtained with classical approaches; only non standard procedures like Moire interferometry, or special artifacts like KGR extensometers may afford some insights on the behavior of the adhesive. Due to their small size, ensuring low perturbation of the strain field, and their innate ability to measure strain and strain gradient along the sensor, fiber Bragg gratings offer a good opportunity to solve this problem, and it is a good example of situations that may benefit from these new sensors. Fiber Bragg gratings may be placed or at the interface, within the adhesive layer, or embedded at the adherents, if these were made of composite material. Tests may be run at different temperatures, changing the adhesive characteristics from brittle to pseudoplastic without additional difficulties. When loading the joint, the strain field is obtained by analyzing the distorted spectrum of the reflected light pulse; the algorithm for doing it has already been published. A comparison with theoretical results is done, and the validity and utility of these sensors for this and similar applications is demonstrated.

Design, Fabrication, and Testing of SMA Enabled Adaptive Chevrons for Jet Noise Reduction

NASA Technical Reports Server (NTRS)

Turner, Travis L.; Buehrle, Ralph D.; Cano, Roberto J.; Fleming, Gary A.

2004-01-01

This study presents the status and results from an effort to design, fabricate, and test an adaptive jet engine chevron concept based upon embedding shape memory alloy (SMA) actuators in a composite laminate, termed a SMA hybrid composite (SMAHC). The approach for fabricating the adaptive SMAHC chevrons involves embedding prestrained Nitinol actuators on one side of the mid-plane of the composite laminate such that thermal excitation generates a thermal moment and deflects the structure. A glass-epoxy pre-preg/Nitinol ribbon material system and a vacuum hot press consolidation approach are employed. A versatile test system for control and measurement of the chevron deflection performance is described. Projection moire interferometry (PMI) is used for global deformation measurement and infrared (IR) thermography is used for 2-D temperature measurement and feedback control. A recently commercialized constitutive model for SMA and SMAHC materials is used in the finite element code ABAQUS to perform nonlinear static analysis of the chevron prototypes. Excellent agreement is achieved between the predicted and measured chevron deflection performance, thereby validating the design tool. Although the performance results presented in this paper fall short of the requirement, the concept is proven and an approach for achieving the performance objectives is evident.

Beam shaping optics to enhance performance of interferometry techniques in grating manufacture

NASA Astrophysics Data System (ADS)

Laskin, Alexander; Laskin, Vadim; Ostrun, Aleksei

2018-02-01

Improving of industrial holographic and interferometry techniques is of great importance in interference lithography, computer-generated holography, holographic data storage, interferometry recording of Bragg gratings as well as gratings of various types in semiconductor industry. Performance of mentioned techniques is essentially enhanced by providing a light beam with flat phase front and flat-top irradiance distribution. Therefore, transformation of Gaussian distribution of a TEM00 laser to flat-top (top hat, uniform) distribution is an important optical task. There are different refractive and diffractive beam shaping approaches used in laser industrial and scientific applications, but only few of them are capable to fulfil the optimum conditions for beam quality demanding holography and interferometry. As a solution it is suggested to apply refractive field mapping beam shaping optics πShaper, which operational principle presumes almost lossless transformation of Gaussian to flat-top beam with flatness of output wavefront, conserving of beam consistency, providing collimated low divergent output beam, high transmittance, extended depth of field, negligible wave aberration, and achromatic design provides capability to work with several lasers with different wavelengths simultaneously. High optical quality of resulting flat-top beam allows applying additional optical components to build various imaging optical systems for variation of beam size and shape to fulfil requirements of a particular application. This paper will describe design basics of refractive beam shapers and optical layouts of their applying in holography and laser interference lithography. Examples of real implementations and experimental results will be presented as well.

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.

Characterizing opto-electret based paper speakers by using a real-time projection Moiré metrology system

NASA Astrophysics Data System (ADS)

Chang, Ya-Ling; Hsu, Kuan-Yu; Lee, Chih-Kung

2016-03-01

Advancement of distributed piezo-electret sensors and actuators facilitates various smart systems development, which include paper speakers, opto-piezo/electret bio-chips, etc. The array-based loudspeaker system possess several advantages over conventional coil speakers, such as light-weightness, flexibility, low power consumption, directivity, etc. With the understanding that the performance of the large-area piezo-electret loudspeakers or even the microfluidic biochip transport behavior could be tailored by changing their dynamic behaviors, a full-field real-time high-resolution non-contact metrology system was developed. In this paper, influence of the resonance modes and the transient vibrations of an arraybased loudspeaker system on the acoustic effect were measured by using a real-time projection moiré metrology system and microphones. To make the paper speaker even more versatile, we combine the photosensitive material TiOPc into the original electret loudspeaker. The vibration of this newly developed opto-electret loudspeaker could be manipulated by illuminating different light-intensity patterns. Trying to facilitate the tailoring process of the opto-electret loudspeaker, projection moiré was adopted to measure its vibration. By recording the projected fringes which are modulated by the contours of the testing sample, the phase unwrapping algorithm can give us a continuous phase distribution which is proportional to the object height variations. With the aid of the projection moiré metrology system, the vibrations associated with each distinctive light pattern could be characterized. Therefore, we expect that the overall acoustic performance could be improved by finding the suitable illuminating patterns. In this manuscript, the system performance of the projection moiré and the optoelectret paper speakers were cross-examined and verified by the experimental results obtained.

One-dimensional angular-measurement-based stitching interferometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Lei; Xue, Junpeng; Gao, Bo

In this paper, we present one-dimensional stitching interferometry based on the angular measurement for high-precision mirror metrology. The tilt error introduced by the stage motion during the stitching process is measured by an extra angular measurement device. The local profile measured by the interferometer in a single field of view is corrected using the measured angle before the piston adjustment in the stitching process. Comparing to the classical software stitching technique, the angle measuring stitching technique is more reliable and accurate in profiling mirror surface at the nanometer level. Experimental results demonstrate the feasibility of the proposed stitching technique. Basedmore » on our measurements, the typical repeatability within 200 mm scanning range is 0.5 nm RMS or less.« less

International Seminar on Laser and Opto-Electronic Technology in Industry: State-of-the-Art Review, Xiamen, People's Republic of China, June 25-28, 1986, Proceedings

NASA Astrophysics Data System (ADS)

Ke, Jingtang; Pryputniewicz, Ryszard J.

Various papers on the state of the art in laser and optoelectronic technology in industry are presented. Individual topics addressed include: wavelength compensation for holographic optical element, optoelectronic techniques for measurement and inspection, new optical measurement methods in Western Europe, applications of coherent optics at ISL, imaging techniques for gas turbine development, the Rolls-Royce experience with industrial holography, panoramic holocamera for tube and borehole inspection, optical characterization of electronic materials, optical strain measurement of rotating components, quantitative interpretation of holograms and specklegrams, laser speckle technique for hydraulic structural model test, study of holospeckle interferometry, common path shearing fringe scanning interferometer, and laser interferometry applied to nondestructive testing of tires.

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.

One-dimensional angular-measurement-based stitching interferometry

DOE PAGES

Huang, Lei; Xue, Junpeng; Gao, Bo; ...

2018-04-05

In this paper, we present one-dimensional stitching interferometry based on the angular measurement for high-precision mirror metrology. The tilt error introduced by the stage motion during the stitching process is measured by an extra angular measurement device. The local profile measured by the interferometer in a single field of view is corrected using the measured angle before the piston adjustment in the stitching process. Comparing to the classical software stitching technique, the angle measuring stitching technique is more reliable and accurate in profiling mirror surface at the nanometer level. Experimental results demonstrate the feasibility of the proposed stitching technique. Basedmore » on our measurements, the typical repeatability within 200 mm scanning range is 0.5 nm RMS or less.« less

Numerical dispersion compensation for Partial Coherence Interferometry and Optical Coherence Tomography.

PubMed

Fercher, A; Hitzenberger, C; Sticker, M; Zawadzki, R; Karamata, B; Lasser, T

2001-12-03

Dispersive samples introduce a wavelength dependent phase distortion to the probe beam. This leads to a noticeable loss of depth resolution in high resolution OCT using broadband light sources. The standard technique to avoid this consequence is to balance the dispersion of the sample byarrangingadispersive materialinthereference arm. However, the impact of dispersion is depth dependent. A corresponding depth dependent dispersion balancing technique is diffcult to implement. Here we present a numerical dispersion compensation technique for Partial Coherence Interferometry (PCI) and Optical Coherence Tomography (OCT) based on numerical correlation of the depth scan signal with a depth variant kernel. It can be used a posteriori and provides depth dependent dispersion compensation. Examples of dispersion compensated depth scan signals obtained from microscope cover glasses are presented.

Interactive Fringe Analysis System: Applications To Moire Contourogram And Interferogram

NASA Astrophysics Data System (ADS)

Yatagai, T.; Idesawa, M.; Yamaashi, Y.; Suzuki, M.

1982-10-01

A general purpose fringe pattern processing facility was developed in order to analyze moire photographs used for scoliosis diagnoses and interferometric patterns in optical shops. A TV camera reads a fringe profile to be analyzed, and peaks of the fringe are detected by a microcomputer. Fringe peak correction and fringe order determination are performed with the man-machine interactive software developed. A light pen facility and an image digitizer are employed for interaction. In the case of two-dimensional fringe analysis, we analyze independently analysis lines parallel to each other and a reference line perpendicular to the parallel analysis lines. Fringe orders of parallel analysis lines are uniquely determined by using the fringe order of the reference line. Some results of analysis of moire contourograms, interferometric testing of silicon wafers, and holographic measurement of thermal deformation are presented.

Vibration measurement of the tympanic membrane of guinea pig temporal bones using time-averaged speckle pattern interferometry

NASA Astrophysics Data System (ADS)

Wada, Hiroshi; Ando, Masayoshi; Takeuchi, Masataka; Sugawara, Hironori; Koike, Takuji; Kobayashi, Toshimitsu; Hozawa, Koji; Gemma, Takashi; Nara, Makoto

2002-05-01

``Time-averaged holography'' and ``holographic interferometry'' enable recording of the complete vibration pattern of a surface within several seconds. The results appear in the form of fringes. Vibration amplitudes smaller than 100 nm are not readily measurable by these techniques, because such small amplitudes produce variations in gray level, but not fringes. In practice, to obtain clear fringes in these measurements, stimulus sound pressures higher than 100 dB SPL must be used. The phase of motion is also not obtainable from such fringe techniques. In this study, a sinusoidal phase modulation technique is described, which allows detection of both small amplitudes of motion and their phase from time-averaged speckle pattern interferometry. In this technique, the laser injection current is modulated and digital image processing is used to analyze the measured patterns. When the sound-pressure level of stimuli is between 70 and 85 dB SPL, this system is applied to measure the vibratory response of the tympanic membrane (TM) of guinea pig temporal bones at frequencies up to 4 kHz where complicated vibration modes are observed. The effect of the bulla on TM displacements is also quantified. Results indicate that this system is capable of measuring the nanometer displacements of the TM, produced by stimuli of 70 dB SPL.

Real-time direct measurement of liquid (water) evaporation by simple disturbance inhibited interfometry technique

NASA Astrophysics Data System (ADS)

Kim, Yong Gi

2017-11-01

A real-time in-situ interferometry method was proposed to measure water (liquid) evaporation directly over the liquid surface inside the reservoir. The direct evaporation measurement relied on the counting the number of sinusoidal fringes. As the water inside reservoir evaporated, the depth of the water decreases a little thus the optical path length changes. Evaporation signals have been determined as a function of the focusing beam position of the signal beam over the liquid surface. In interferometry technique, the most limiting factors are surface disturbances and vibrations over the liquid surface. This limiting factor was simply inhibited by placing a long cylindrical aluminum tube around the signal beam of the interferometer over the liquid surface. A small diameter cylindrical Al tube diminished vibrations and wind induced surface ripples more effectively than that of the larger one. Water evaporation was successfully measured in real-time with a warm water and cold water even under windy condition with an electric fan. The experimental results demonstrated that the interferometry technique allows determining of liquid evaporation in real-time. Interferometric technique opens up a new possibility of methodology for liquid evaporation measurement even in several environmental disturbances, such as, vibration, surface disturbance, temperature change and windy environments.

Double-atomic layer of Tl on Si(111): Atomic arrangement and electronic properties

NASA Astrophysics Data System (ADS)

Mihalyuk, Alexey N.; Bondarenko, Leonid V.; Tupchaya, Alexandra Y.; Gruznev, Dimitry V.; Chou, Jyh-Pin; Hsing, Cheng-Rong; Wei, Ching-Ming; Zotov, Andrey V.; Saranin, Alexander A.

2018-02-01

Metastable double-atomic layer of Tl on Si(111) has recently been found to display interesting electric properties, namely superconductivity below 0.96 K and magnetic-field-induced transition into an insulating phase intermediated by a quantum metal state. In the present work, using a set of experimental techniques, including low-energy electron diffraction, scanning tunneling microscopy, angle-resolved photoelectron spectroscopy, in a combination with density-functional-theory calculations, we have characterized atomic and electronic properties of the Tl double layer on Si(111). The double Tl layer has been concluded to contain ∼ 2.4 monolayer of Tl. A top Tl layer has a '1 × 1' basic structure and displays 6 × 6 moiré pattern which originates from various residence sites of Tl atoms. Upon cooling below ∼ 140 K, the 6 × 6 moiré pattern changes to that having a 6√{ 3} × 6√{ 3} periodicity. However, the experimentally determined electron band dispersions show a 1 × 1 periodicity. The calculated band structure unfolded into the 1 × 1 surface Brillouin zone reproduces well the main features of the photoelectron spectra.

Software system design for the non-null digital Moiré interferometer

NASA Astrophysics Data System (ADS)

Chen, Meng; Hao, Qun; Hu, Yao; Wang, Shaopu; Li, Tengfei; Li, Lin

2016-11-01

Aspheric optical components are an indispensable part of modern optics systems. With the development of aspheric optical elements fabrication technique, high-precision figure error test method of aspheric surfaces is a quite urgent issue now. We proposed a digital Moiré interferometer technique (DMIT) based on partial compensation principle for aspheric and freeform surface measurement. Different from traditional interferometer, DMIT consists of a real and a virtual interferometer. The virtual interferometer is simulated with Zemax software to perform phase-shifting and alignment. We can get the results by a series of calculation with the real interferogram and virtual interferograms generated by computer. DMIT requires a specific, reliable software system to ensure its normal work. Image acquisition and data processing are two important parts in this system. And it is also a challenge to realize the connection between the real and virtual interferometer. In this paper, we present a software system design for DMIT with friendly user interface and robust data processing features, enabling us to acquire the figure error of the measured asphere. We choose Visual C++ as the software development platform and control the ideal interferometer by using hybrid programming with Zemax. After image acquisition and data transmission, the system calls image processing algorithms written with Matlab to calculate the figure error of the measured asphere. We test the software system experimentally. In the experiment, we realize the measurement of an aspheric surface and prove the feasibility of the software system.

Essential features of residual stress determination in thin-walled plane structures in a base of whole field interferometric measurements

NASA Astrophysics Data System (ADS)

Pisarev, Vladimir S.; Odintsev, I.; Balalov, V.; Apalkov, A.

2003-05-01

Sophisticated technique for reliable quantitative deriving residual stress values from initial experimental data, which are inherent in combined implementing the hole drilling method with both holographic and speckle interferometry, is described in detail. The approach developed includes both possible ways of obtaining initial experimental information. The first of them consists of recording a set of required interference fringe patterns, which are resulted from residual stress energy release after through hole drilling, in two orthogonal directions that coincide with principal strain directions. The second way is obtaining a series of interrelated fringe patterns when a direction of either observation in reflection hologram interferometry or dual-beam illumination in speckle interferometry lies arbitrary with respect to definite principal strain direction. A set of the most typical both actual and analogous reference fringe patterns, which are related to both reflection hologram and dual-beam speckle interferometry, are presented.

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.

Aberration correction in wide-field fluorescence microscopy by segmented-pupil image interferometry.

PubMed

Scrimgeour, Jan; Curtis, Jennifer E

2012-06-18

We present a new technique for the correction of optical aberrations in wide-field fluorescence microscopy. Segmented-Pupil Image Interferometry (SPII) uses a liquid crystal spatial light modulator placed in the microscope's pupil plane to split the wavefront originating from a fluorescent object into an array of individual beams. Distortion of the wavefront arising from either system or sample aberrations results in displacement of the images formed from the individual pupil segments. Analysis of image registration allows for the local tilt in the wavefront at each segment to be corrected with respect to a central reference. A second correction step optimizes the image intensity by adjusting the relative phase of each pupil segment through image interferometry. This ensures that constructive interference between all segments is achieved at the image plane. Improvements in image quality are observed when Segmented-Pupil Image Interferometry is applied to correct aberrations arising from the microscope's optical path.

Optical aperture synthesis with electronically connected telescopes

PubMed Central

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

2015-01-01

Highest resolution imaging in astronomy is achieved by interferometry, connecting telescopes over increasingly longer distances and at successively shorter wavelengths. Here, we present the first diffraction-limited images in visual light, produced by an array of independent optical telescopes, connected electronically only, with no optical links between them. With an array of small telescopes, second-order optical coherence of the sources is measured through intensity interferometry over 180 baselines between pairs of telescopes, and two-dimensional images reconstructed. The technique aims at diffraction-limited optical aperture synthesis over kilometre-long baselines to reach resolutions showing details on stellar surfaces and perhaps even the silhouettes of transiting exoplanets. Intensity interferometry circumvents problems of atmospheric turbulence that constrain ordinary interferometry. Since the electronic signal can be copied, many baselines can be built up between dispersed telescopes, and over long distances. Using arrays of air Cherenkov telescopes, this should enable the optical equivalent of interferometric arrays currently operating at radio wavelengths. PMID:25880705

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.

Method for 3D profilometry measurement based on contouring moire fringe

NASA Astrophysics Data System (ADS)

Shi, Zhiwei; Lin, Juhua

2007-12-01

3D shape measurement is one of the most active branches of optical research recently. A method of 3D profilometry measurement by the combination of Moire projection method and phase-shifting technology based on SCM (Single Chip Microcomputer) control is presented in the paper. Automatic measurement of 3D surface profiles can be carried out by applying this method with high speed and high precision.

Compact portable diffraction moire interferometer

DOEpatents

Deason, V.A.; Ward, M.B.

1988-05-23

A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observations means including film and video cameras may be used to view and record the resultant fringe patterns. 7 figs.

Parasol cell mosaics are unlikely to drive the formation of structured orientation maps in primary visual cortex.

PubMed

Hore, Victoria R A; Troy, John B; Eglen, Stephen J

2012-11-01

The receptive fields of on- and off-center parasol cell mosaics independently tile the retina to ensure efficient sampling of visual space. A recent theoretical model represented the on- and off-center mosaics by noisy hexagonal lattices of slightly different density. When the two lattices are overlaid, long-range Moiré interference patterns are generated. These Moiré interference patterns have been suggested to drive the formation of highly structured orientation maps in visual cortex. Here, we show that noisy hexagonal lattices do not capture the spatial statistics of parasol cell mosaics. An alternative model based upon local exclusion zones, termed as the pairwise interaction point process (PIPP) model, generates patterns that are statistically indistinguishable from parasol cell mosaics. A key difference between the PIPP model and the hexagonal lattice model is that the PIPP model does not generate Moiré interference patterns, and hence stimulated orientation maps do not show any hexagonal structure. Finally, we estimate the spatial extent of spatial correlations in parasol cell mosaics to be only 200-350 μm, far less than that required to generate Moiré interference. We conclude that parasol cell mosaics are too disordered to drive the formation of highly structured orientation maps in visual cortex.

Moiré superlattice-level stick-slip instability originated from geometrically corrugated graphene on a strongly interacting substrate

NASA Astrophysics Data System (ADS)

Shi, Ruoyu; Gao, Lei; Lu, Hongliang; Li, Qunyang; Ma, Tian-Bao; Guo, Hui; Du, Shixuan; Feng, Xi-Qiao; Zhang, Shuai; Liu, Yanmin; Cheng, Peng; Hu, Yuan-Zhong; Gao, Hong-Jun; Luo, Jianbin

2017-06-01

Two dimensional (2D) materials often exhibit novel properties due to various coupling effects with their supporting substrates. Here, using friction force microscopy (FFM), we report an unusual moiré superlattice-level stick-slip instability on monolayer graphene epitaxially grown on Ru(0 0 0 1) substrate. Instead of smooth friction modulation, a significant long-range stick-slip sawtooth modulation emerges with a period coinciding with the moiré superlattice structure, which is robust against high external loads and leads to an additional channel of energy dissipation. In contrast, the long-range stick-slip instability reduces to smooth friction modulation on graphene/Ir(1 1 1) substrate. The moiré superlattice-level slip instability could be attributed to the large sliding energy barrier, which arises from the morphological corrugation of graphene on Ru(0 0 0 1) surface as indicated by density functional theory (DFT) calculations. The locally steep humps acting as obstacles opposing the tip sliding, originates from the strong interfacial electronic interaction between graphene and Ru(0 0 0 1). This study opens an avenue for modulating friction by tuning the interfacial atomic interaction between 2D materials and their substrates.

Origins of Moiré Patterns in CVD-grown MoS2 Bilayer Structures at the Atomic Scales.

PubMed

Wang, Jin; Namburu, Raju; Dubey, Madan; Dongare, Avinash M

2018-06-21

The chemical vapor deposition (CVD)-grown two-dimensional molybdenum disulfide (MoS 2 ) structures comprise of flakes of few layers with different dimensions. The top layers are relatively smaller in size than the bottom layers, resulting in the formation of edges/steps across adjacent layers. The strain response of such few-layer terraced structures is therefore likely to be different from exfoliated few-layered structures with similar dimensions without any terraces. In this study, the strain response of CVD-grown few-layered MoS 2 terraced structures is investigated at the atomic scales using classic molecular dynamics (MD) simulations. MD simulations suggest that the strain relaxation of CVD-grown triangular terraced structures is observed in the vertical displacement of the atoms across the layers that results in the formation of Moiré patterns. The Moiré islands are observed to nucleate at the corners or edges of the few-layered structure and propagate inwards under both tensile and compressive strains. The nucleation of these islands is observed to happen at tensile strains of ~ 2% and at compressive strains of ~2.5%. The vertical displacements of the atoms and the dimensions of the Moiré islands predicted using the MD simulation are in excellent agreement with that observed experimentally.

Topological mosaics in moiré superlattices of van der Waals heterobilayers

NASA Astrophysics Data System (ADS)

Tong, Qingjun; Yu, Hongyi; Zhu, Qizhong; Wang, Yong; Xu, Xiaodong; Yao, Wang

2017-04-01

Van der Waals (vdW) heterostructures formed by two-dimensional atomic crystals provide a powerful approach towards designer condensed matter systems. Incommensurate heterobilayers with small twisting and/or lattice mismatch lead to the interesting concept of moiré superlattices, where the atomic registry is locally indistinguishable from commensurate bilayers but has local-to-local variation over long range. Here we show that such moiré superlattices can lead to periodic modulation of local topological order in vdW heterobilayers formed by two massive Dirac materials. By tuning the vdW heterojunction from normal to the inverted type-II regime via an interlayer bias, the commensurate heterobilayer can become a topological insulator (TI), depending on the interlayer hybridization controlled by the atomic registry between the vdW layers. This results in a mosaic pattern of TI regions and normal insulator (NI) regions in moiré superlattices, where topologically protected helical modes exist at the TI/NI phase boundaries. By using symmetry-based k .p and tight-binding models, we predict that this topological phenomenon can be present in inverted transition metal dichalcogenides heterobilayers. Our work points to a new means of realizing programmable and electrically switchable topological superstructures from two-dimensional arrays of TI nano-dots to one-dimensional arrays of TI nano-stripes.

Extracting attosecond delays from spectrally overlapping interferograms

NASA Astrophysics Data System (ADS)

Jordan, Inga; Wörner, Hans Jakob

2018-02-01

Attosecond interferometry is becoming an increasingly popular technique for measuring the dynamics of photoionization in real time. Whereas early measurements focused on atomic systems with very simple photoelectron spectra, the technique is now being applied to more complex systems including isolated molecules and solids. The increase in complexity translates into an augmented spectral congestion, unavoidably resulting in spectral overlap in attosecond interferograms. Here, we discuss currently used methods for phase retrieval and introduce two new approaches for determining attosecond photoemission delays from spectrally overlapping photoelectron spectra. We show that the previously used technique, consisting in the spectral integration of the areas of interest, does in general not provide reliable results. Our methods resolve this problem, thereby opening the technique of attosecond interferometry to complex systems and fully exploiting its specific advantages in terms of spectral resolution compared to attosecond streaking.

Diffuse reflectance imaging for non-melanoma skin cancer detection using laser feedback interferometry

NASA Astrophysics Data System (ADS)

Mowla, Alireza; Taimre, Thomas; Lim, Yah L.; Bertling, Karl; Wilson, Stephen J.; Prow, Tarl W.; Soyer, H. P.; Rakić, Aleksandar D.

2016-04-01

We propose a compact, self-aligned, low-cost, and versatile infrared diffuse-reflectance laser imaging system using a laser feedback interferometry technique with possible applications in in vivo biological tissue imaging and skin cancer detection. We examine the proposed technique experimentally using a three-layer agar skin phantom. A cylindrical region with a scattering rate lower than that of the surrounding normal tissue was used as a model for a non-melanoma skin tumour. The same structure was implemented in a Monte Carlo computational model. The experimental results agree well with the Monte Carlo simulations validating the theoretical basis of the technique. Results prove the applicability of the proposed technique for biological tissue imaging, with the capability of depth sectioning and a penetration depth of well over 1.2 mm into the skin phantom.

Optical measurement methods in thermogasdynamics

NASA Technical Reports Server (NTRS)

Stursberg, K.; Erhardt, K.; Krahr, W.; Becker, M.

1978-01-01

A review is presented of a number of optical methods of flow measurements. Consideration is given to such spectroscopic methods as emission and absorption techniques, electron beam-stimulated fluorescence, and light scattering - Rayleigh, Raman and Mie - methods. The following visualization methods are also discussed: shadow photography, schlieren photography, interferometry, holographic interferometry, laser anemometry, particle holography, and electron-excitation imaging. A large bibliography is presented and the work is copiously illustrated with figures and photographs.

Normal and Differential SAR Interferometry

DTIC Science & Technology

2005-02-01

incorporating the use of a rough DEM. [ Adragna 1995]. The same technique is also used for flat Earth removal, and for differential interferometry (Cap.5...and F. Adragna , 1994. Radar Interferometric Mapping of Deformation in the Year After the Landers Earthquake, Nature, Vol. 369, pp. 227-230 Massonnet...D., M. Rossi, C. Carmona, F. Adragna , G. Peltzer, K. Feigi, and T. Rabaute, 1993. The Displacement Field of the Landers Earthquake Mapped by Radar

Technology for Elevated Temperature Tests of Structural Panels

NASA Technical Reports Server (NTRS)

Thornton, E. A.

1999-01-01

A technique for full-field measurement of surface temperature and in-plane strain using a single grid imaging technique was demonstrated on a sample subjected to thermally-induced strain. The technique is based on digital imaging of a sample marked by an alternating line array of La2O2S:Eu(+3) thermographic phosphor and chromium illuminated by a UV lamp. Digital images of this array in unstrained and strained states were processed using a modified spin filter. Normal strain distribution was determined by combining unstrained and strained grid images using a single grid digital moire technique. Temperature distribution was determined by ratioing images of phosphor intensity at two wavelengths. Combined strain and temperature measurements demonstrated on the thermally heated sample were DELTA-epsilon = +/- 250 microepsilon and DELTA-T = +/- 5 K respectively with a spatial resolution of 0.8 mm.

Shot noise-limited Cramér-Rao bound and algorithmic sensitivity for wavelength shifting interferometry

NASA Astrophysics Data System (ADS)

Chen, Shichao; Zhu, Yizheng

2017-02-01

Sensitivity is a critical index to measure the temporal fluctuation of the retrieved optical pathlength in quantitative phase imaging system. However, an accurate and comprehensive analysis for sensitivity evaluation is still lacking in current literature. In particular, previous theoretical studies for fundamental sensitivity based on Gaussian noise models are not applicable to modern cameras and detectors, which are dominated by shot noise. In this paper, we derive two shot noiselimited theoretical sensitivities, Cramér-Rao bound and algorithmic sensitivity for wavelength shifting interferometry, which is a major category of on-axis interferometry techniques in quantitative phase imaging. Based on the derivations, we show that the shot noise-limited model permits accurate estimation of theoretical sensitivities directly from measured data. These results can provide important insights into fundamental constraints in system performance and can be used to guide system design and optimization. The same concepts can be generalized to other quantitative phase imaging techniques as well.

The use of Electronic Speckle Pattern Interferometry (ESPI) in the crack propagation analysis of epoxy resins

NASA Astrophysics Data System (ADS)

Herbert, D. P.; Al-Hassani, A. H. M.; Richardson, M. O. W.

The ESPI (electronic speckle pattern interferometry) technique at high magnification levels is demonstrated to be of considerable value in interpreting the fracture behaviour of epoxy resins. The fracture toughness of powder coating system at different thicknesses has been measured using a TDCB (tapered double cantilever beam) technique and the deformation zone at the tip of the moving crack monitored. Initial indications are that a mechanistic changeover occurs at a critical bond (coating) thickness and that this is synonymous with the occurence of a fracture toughness maximum, which in turn is associated with a deformation zone of specific diameter.

DH and ESPI laser interferometry applied to the restoration shrinkage assessment

NASA Astrophysics Data System (ADS)

Campos, L. M. P.; Parra, D. F.; Vasconcelos, M. R.; Vaz, M.; Monteiro, J.

2014-01-01

In dental restoration postoperative marginal leakage is commonly associated to polymerization shrinkage effects. In consequence the longevity and quality of restorative treatment depends on the shrinkage mechanisms of the composite filling during the polymerization. In this work the development of new techniques for evaluation of those effects under light-induced polymerization of dental nano composite fillings is reported. The composite resins activated by visible light, initiate the polymerization process by absorbing light in wavelengths at about 470 nm. The techniques employed in the contraction assessment were digital holography (DH) and Electronic Speckle Pattern Interferometry (ESPI) based on laser interferometry. A satisfactory resolution was achieved in the non-contact displacement field measurements on small objects concerning the experimental dental samples. According to a specific clinical protocol, natural teeth were used (human mandibular premolars). A class I cavity was drilled and restored with nano composite material, according to Black principles. The polymerization was monitored by DH and ESPI in real time during the cure reaction of the restoration. The total displacement reported for the material in relation of the tooth wall was 3.7 μm (natural tooth). The technique showed the entire tooth surface (wall) deforming during polymerization shrinkage.

Persistent Scatterer Interferometry subsidence data exploitation using spatial tools: The Vega Media of the Segura River Basin case study

NASA Astrophysics Data System (ADS)

Tomas, R.; Herrera, G.; Cooksley, G.; Mulas, J.

2011-04-01

SummaryThe aim of this paper is to analyze the subsidence affecting the Vega Media of the Segura River Basin, using a Persistent Scatterers Interferometry technique (PSI) named Stable Point Network (SPN). This technique is capable of estimating mean deformation velocity maps of the ground surface and displacement time series from Synthetic Aperture Radar (SAR) images. A dataset acquired between January 2004 and December 2008 from ERS-2 and ENVISAT sensors has been processed measuring maximum subsidence and uplift rates of -25.6 and 7.54 mm/year respectively for the whole area. These data have been validated against ground subsidence measurements and compared with subsidence triggering and conditioning factors by means of a Geographical Information System (GIS). The spatial analysis shows a good relationship between subsidence and piezometric level evolution, pumping wells location, river distance, geology, the Arab wall, previously proposed subsidence predictive model and soil thickness. As a consequence, the paper shows the usefulness and the potential of combining Differential SAR Interferometry (DInSAR) and spatial analysis techniques in order to improve the knowledge of this kind of phenomenon.

MO-AB-BRA-03: Calorimetry-Based Absorbed Dose to Water Measurements Using Interferometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flores-Martinez, E; Malin, M; DeWerd, L

2015-06-15

Purpose: Interferometry-based calorimetry is a novel technique to measure radiation-induced temperature changes allowing the measurement of absorbed dose to water (ADW). There are no mechanical components in the field. This technique also has the possibility of obtaining 2D dose distributions. The goal of this investigation is to calorimetrically-measure doses between 2.5 and 5 Gy over a single projection in a photon beam using interferometry and compare the results with doses calculated using the TG-51 linac calibration. Methods: ADW was determined by measuring radiation-induced phase shifts (PSs) of light passing through water irradiated with a 6 MV photon beam. A 9×9×9more » cm{sup 3} glass phantom filled with water and placed in an arm of a Michelson interferometer was irradiated with 300, 400, 500 and 600 monitor units. The whole system was thermally insulated to achieve sufficient passive temperature control. The depth of measurement was 4.5 cm with a field size of 7×7 cm{sup 2}. The intensity of the fringe pattern was monitored with a photodiode and used to calculate the time-dependent PS curve. Data was acquired 60 s before and after the irradiation. The radiation-induced PS was calculated by taking the difference in the pre- and post-irradiation drifts extrapolated to the midpoint of the irradiation. Results were compared to computed doses. Results: Average comparison of calculated ADW values with interferometry-measured values showed an agreement to within 9.5%. k=1 uncertainties were 4.3% for calculations and 14.7% for measurements. The dominant source of uncertainty for the measurements was a temperature drift of about 30 µK/s caused by heat conduction from the interferometer’s surroundings. Conclusion: This work presented the first absolute ADW measurements using interferometry in the dose range of linac-based radiotherapy. Future work to improve measurements’ reproducibility includes the implementation of active thermal control techniques.« less

Laser interferometry for the determination of thickness distributions of low absorbing films and their spatial and thickness resolutions.

PubMed

Mishima, T; Kao, K C

1982-03-15

New laser interferometry has been developed, based on the principle that a 2-D fringe pattern can be produced by interference of spatially coherent light beams. To avoid the effect of reflection from the back surface of the substrate, the Brewster angle of incidence is adopted; to suppress the effect of diffraction, a lens or a lens system is used. This laser interferometry is an efficient nondestructive technique for the determination of thickness distributions or uniformities of low absorbing films on transparent substrates over a large area without involving laborious computations. The limitation of spatial resolution, thickness resolution, and visibility of fringes is fully analyzed.

A recent history of science cases for optical interferometry

NASA Astrophysics Data System (ADS)

Defrère, Denis; Aerts, Conny; Kishimoto, Makoto; Léna, Pierre

2018-04-01

Optical long-baseline interferometry is a unique and powerful technique for astronomical research. Since the 1980's (with I2T, GI2T, Mark I to III, SUSI, ...), optical interferometers have produced an increasing number of scientific papers covering various fields of astrophysics. As current interferometric facilities are reaching their maturity, we take the opportunity in this paper to summarize the conclusions of a few key meetings, workshops, and conferences dedicated to interferometry. We present the most persistent recommendations related to science cases and discuss some key technological developments required to address them. In the era of extremely large telescopes, optical long-baseline interferometers will remain crucial to probe the smallest spatial scales and make breakthrough discoveries.

Deployment Repeatability

DTIC Science & Technology

2016-08-31

photogrammetry to track a set of LEDS in two dimensions, a method that was able to resolve 2.2-mm lateral displacements of a 40-meter boom. This method... displacements . Sub-milliradian repeatability in MOIRE [This is a stand-in section for the MOIRE case study, which Dave Waller is getting through...The structure will most likely be under this stowed state for a long time under displacement paths and put this data into a computationally cheap 1

Gate-dependent Pseudospin Mixing in Graphene/boron Nitride Moire Superlattices

DTIC Science & Technology

2014-08-31

LETTERS PUBLISHED ONLINE: 31 AUGUST 2014 | DOI : 10.1038/NPHYS3075 Gate-dependent pseudospin mixing in graphene/boron nitride moiré superlattices... Dirac –Weyl spinors with a two-component pseudospin1–12. The unique pseudospin structure of Dirac electrons leads to emerging phenomena such as the...massless Dirac cone2, anomalous quantum Hall eect2,3, and Klein tunnelling4,5 in graphene. The capability to manipulate electron pseudospin is highly

Multipulsed dynamic moire interferometer

DOEpatents

Deason, Vance A.

1991-01-01

An improved dynamic moire interferometer comprised of a lasing medium providing a plurality of beams of coherent light, a multiple q-switch producing multiple trains of 100,000 or more pulses per second, a combining means collimating multiple trains of pulses into substantially a single train and directing beams to specimen gratings affixed to a test material, and a controller, triggering and sequencing the emission of the pulses with the occurrence and recording of a dynamic loading event.

Characterization of TEM Moiré Patterns Originating from Two Monolayer Graphenes Grown on the Front and Back Sides of a Copper Substrate by CVD Method

NASA Astrophysics Data System (ADS)

Yamazaki, Kenji; Maehara, Yosuke; Gohara, Kazutoshi

2018-06-01

The number of layers affects the electronic properties of graphene owing to its unique band structure, called the Dirac corn. Raman spectroscopy is a key diagnostic tool for identifying the number of graphene layers and for determining their physical properties. Here, we observed moiré structures in transmission electron microscopy (TEM) observations; these are signature patterns in multilayer, although Raman spectra showed the typical intensity of the 2D/G peak in the monolayer. We also performed a multi-slice TEM image simulation to compare the 3D atomic structures of the two graphene membranes with experimental TEM images. We found that the experimental moiré image was constructed with a 9-12 Å interlayer distance between graphene membranes. This structure was constructed by transferring CVD-grown graphene films that formed on both sides of the Cu substrate at once.

Optical authentication based on moiré effect of nonlinear gratings in phase space

NASA Astrophysics Data System (ADS)

Liao, Meihua; He, Wenqi; Wu, Jiachen; Lu, Dajiang; Liu, Xiaoli; Peng, Xiang

2015-12-01

An optical authentication scheme based on the moiré effect of nonlinear gratings in phase space is proposed. According to the phase function relationship of the moiré effect in phase space, an arbitrary authentication image can be encoded into two nonlinear gratings which serve as the authentication lock (AL) and the authentication key (AK). The AL is stored in the authentication system while the AK is assigned to the authorized user. The authentication procedure can be performed using an optoelectronic approach, while the design process is accomplished by a digital approach. Furthermore, this optical authentication scheme can be extended for multiple users with different security levels. The proposed scheme can not only verify the legality of a user identity, but can also discriminate and control the security levels of legal users. Theoretical analysis and simulation experiments are provided to verify the feasibility and effectiveness of the proposed scheme.

Mapping Ocean Surface Topography with a Synthetic-Aperture Interferometry Radar

NASA Technical Reports Server (NTRS)

Fu, Lee-Lueng; Rodriguez, Ernesto

2006-01-01

We propose to apply the technique of synthetic aperture radar interferometry to the measurement of ocean surface topography at spatial resolution approaching 1 km. The measurement will have wide ranging applications in oceanography, hydrology. and marine geophysics. The oceanographic and related societal applications are briefly discussed in the paper. To meet the requirements for oceanographic applications, the instrument must be flown in an orbit with proper sampling of ocean tides.

Normal and Differential SAR Interferometry

DTIC Science & Technology

2007-02-01

incorporating the use of a rough DEM. [ Adragna 1995]. The same technique is also used for flat Earth removal, and for differential Interferometry (Chap..5...available at http://www.estec.esa.nl/confannoun/99b02/index.html Massonnet, D., K. Feigi, M. Rossi, and F. Adragna , 1994. Radar Interferometric Mapping...of Deformation in the Year After the Landers Earthquake, Nature, Vol. 369, pp. 227-230 Massonnet, D., M. Rossi, C. Carmona, F. Adragna , G. Peltzer

Holographic interferometry of transparent media with reflection from imbedded test objects

NASA Technical Reports Server (NTRS)

Prikryl, I.; Vest, C. M.

1981-01-01

In applying holographic interferometry, opaque objects blocking a portion of the optical beam used to form the interferogram give rise to incomplete data for standard computer tomography algorithms. An experimental technique for circumventing the problem of data blocked by opaque objects is presented. The missing data are completed by forming an interferogram using light backscattered from the opaque object, which is assumed to be diffuse. The problem of fringe localization is considered.

Localized analysis of paint-coat drying using dynamic speckle interferometry

NASA Astrophysics Data System (ADS)

Sierra-Sosa, Daniel; Tebaldi, Myrian; Grumel, Eduardo; Rabal, Hector; Elmaghraby, Adel

2018-07-01

The paint-coating is part of several industrial processes, including the automotive industry, architectural coatings, machinery and appliances. These paint-coatings must comply with high quality standards, for this reason evaluation techniques from paint-coatings are in constant development. One important factor from the paint-coating process is the drying, as it has influence on the quality of final results. In this work we present an assessment technique based on the optical dynamic speckle interferometry, this technique allows for the temporal activity evaluation of the paint-coating drying process, providing localized information from drying. This localized information is relevant in order to address the drying homogeneity, optimal drying, and quality control. The technique relies in the definition of a new temporal history of the speckle patterns to obtain the local activity; this information is then clustered to provide a convenient indicative of different drying process stages. The experimental results presented were validated using the gravimetric drying curves

Single-shot Z(eff) dense plasma diagnostic through simultaneous refraction and attenuation measurements with a Talbot-Lau x-ray moiré deflectometer.

PubMed

Valdivia, M P; Stutman, D; Finkenthal, M

2015-04-01

The Talbot-Lau x-ray moiré deflectometer is a powerful plasma diagnostic capable of delivering simultaneous refraction and attenuation information through the accurate detection of x-ray phase shift and intensity. The diagnostic can provide the index of refraction n=1-δ+iβ of an object (dense plasma, for example) placed in the x-ray beam by independently measuring both δ and β, which are directly related to the electron density n(e) and the attenuation coefficient μ, respectively. Since δ and β depend on the effective atomic number Z(eff), a map can be obtained from the ratio between phase and absorption images acquired in a single shot. The Talbot-Lau x-ray moiré deflectometer and its corresponding data acquisition and processing are briefly described to illustrate how the above is achieved; Z(eff) values of test objects within the 4-12 range were obtained experimentally through simultaneous refraction and attenuation measurements. We show that Z(eff) mapping of objects does not require previous knowledge of sample length or shape. The determination of Z(eff) from refraction and attenuation measurements with moiré deflectometry could be of high interest to various domains of high energy density research, such as shocked materials and inertial confinement fusion experiments, as well as material science and nondestructive testing.

Epitaxial hexagonal boron nitride on Ir(111): A work function template

NASA Astrophysics Data System (ADS)

Schulz, Fabian; Drost, Robert; Hämäläinen, Sampsa K.; Demonchaux, Thomas; Seitsonen, Ari P.; Liljeroth, Peter

2014-06-01

Hexagonal boron nitride (h-BN) is a prominent member in the growing family of two-dimensional materials with potential applications ranging from being an atomically smooth support for other two-dimensional materials to templating growth of molecular layers. We have studied the structure of monolayer h-BN grown by chemical vapor deposition on Ir(111) by low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS) experiments and state-of-the-art density functional theory (DFT) calculations. The lattice mismatch between the h-BN and Ir(111) surface results in the formation of a moiré superstructure with a periodicity of ˜29 Å and a corrugation of ˜0.4 Å. By measuring the field emission resonances above the h-BN layer, we find a modulation of the work function within the moiré unit cell of ˜0.5 eV. DFT simulations for a 13-on-12 h-BN/Ir(111) unit cell confirm our experimental findings and allow us to relate the change in the work function to the subtle changes in the interaction between boron and nitrogen atoms and the underlying substrate atoms within the moiré unit cell. Hexagonal boron nitride on Ir(111) combines weak topographic corrugation with a strong work function modulation over the moiré unit cell. This makes h-BN/Ir(111) a potential substrate for electronically modulated thin film and heterosandwich structures.

Robust mechanical property measurements of fibrous parylene-C thin-film substrate via moiré contouring technology.

PubMed

Sciammarella, F M; Sciammarella, C A; Lamberti, L; Styrcula, M; Wei, L; Lakhtakia, A

2013-04-01

Parylene-C is a bio-inert, bio-compatible and relatively inexpensive material with many bio-medical applications from coatings for implantable devices to bio-scaffolds. The main objective of this research was to demonstrate a novel approach to accurately measure the mechanical properties of free-standing fibrous thin-film substrates (TFS) of parylene-C. For that purpose, a two-stage experimental protocol based on the use of moiré contouring technology was developed. In this protocol, local measurements employing an advanced moiré setup that uses non-conventional illumination (i.e. evanescent field) are first performed to gather high-resolution information on a small region of the specimen; then, global measurements based on shadow moiré are performed to monitor the overall behavior of the membrane. The protocol was first calibrated for an aluminum foil and then partially applied to the fibrous parylene-C TFS. Material properties extracted from experiments are f0ully consistent with the data reported in literature and the results of a hybrid identification procedure based on the combination of finite element analysis and nonlinear optimization. The results will help lay the foundation for developing a comprehensive understanding of the influence that morphology and stresses play in the ability to enhance and sustain cell growth and tissue development, for biomedical applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

Analyzing refractive index profiles of confined fluids by interferometry.

PubMed

Kienle, Daniel F; Kuhl, Tonya L

2014-12-02

This work describes an interferometry data analysis method for determining the optical thickness of thin films or any variation in the refractive index of a fluid or film near a surface. In particular, the method described is applied to the analysis of interferometry data taken with a surface force apparatus (SFA). The technique does not require contacting or confining the fluid or film. By analyzing interferometry data taken at many intersurface separation distances out to at least 300 nm, the properties of a film can be quantitatively determined. The film can consist of material deposited on the surface, like a polymer brush, or variation in a fluid's refractive index near a surface resulting from, for example, a concentration gradient, depletion in density, or surface roughness. The method is demonstrated with aqueous polyethylenimine (PEI) adsorbed onto mica substrates, which has a large concentration and therefore refractive index gradient near the mica surface. The PEI layer thickness determined by the proposed method is consistent with the thickness measured by conventional SFA methods. Additionally, a thorough investigation of the effects of random and systematic error in SFA data analysis and modeling via simulations of interferometry is described in detail.

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.

Theory and Applications of Surface Plasmon Resonance, Resonant Mirror, Resonant Waveguide Grating, and Dual Polarization Interferometry Biosensors

PubMed Central

Daghestani, Hikmat N.; Day, Billy W.

2010-01-01

Biosensors have been used extensively in the scientific community for several purposes, most notably to determine association and dissociation kinetics, protein-ligand, protein-protein, or nucleic acid hybridization interactions. A number of different types of biosensors are available in the field, each with real or perceived benefits over the others. This review discusses the basic theory and operational arrangements of four commercially available types of optical biosensors: surface plasmon resonance, resonant mirror, resonance waveguide grating, and dual polarization interferometry. The different applications these techniques offer are discussed from experiments and results reported in recently published literature. Additionally, recent advancements or modifications to the current techniques are also discussed. PMID:22163431

Challenging the ‘Big G’ measurement with atoms and light

NASA Astrophysics Data System (ADS)

Rosi, Gabriele

2016-10-01

The measurement of the Newtonian gravity constant G is a formidable task. Starting from the first determination made by Henry Cavendish in 1798, several attempts have been made in order to improve knowledge of its value. Nevertheless, despite these efforts, its uncertainty has decreased only by a factor of ten per century. Cold atom interferometry represents a conceptually different technique to challenge the G measurement, a feature that is crucial in order to identify discrepancies among previous measurements. In this review paper, after a short introduction on the traditional measurement techniques, I will describe and discuss past and ongoing G determination based on atom interferometry, highlighting for each of them the most significant aspects.

Circumstellar Matter Studied by Spectrally-Resolved Interferometry

NASA Astrophysics Data System (ADS)

Millour, F.

2012-12-01

This paper describes some generalities about spectro-interferometry and the role it has played in the last decade for the better understanding of circumstellar matter. I provide a small history of the technique and its origins, and recall the basics of differential phase and its central role for the recent discoveries. I finally provide a small set of simple interpretations of differential phases for specific astrophysical cases, and intend to provide a "cookbook" for the other cases.

Phase recovery in temporal speckle pattern interferometry using the generalized S-transform.

PubMed

Federico, Alejandro; Kaufmann, Guillermo H

2008-04-15

We propose a novel approach based on the generalized S-transform to retrieve optical phase distributions in temporal speckle pattern interferometry. The performance of the proposed approach is compared with those given by well-known techniques based on the continuous wavelet, the Hilbert transforms, and a smoothed time-frequency distribution by analyzing interferometric data degraded by noise, nonmodulating pixels, and modulation loss. The advantages and limitations of the proposed phase retrieval approach are discussed.

Imaging of acoustic fields using optical feedback interferometry.

PubMed

Bertling, Karl; Perchoux, Julien; Taimre, Thomas; Malkin, Robert; Robert, Daniel; Rakić, Aleksandar D; Bosch, Thierry

2014-12-01

This study introduces optical feedback interferometry as a simple and effective technique for the two-dimensional visualisation of acoustic fields. We present imaging results for several pressure distributions including those for progressive waves, standing waves, as well as the diffraction and interference patterns of the acoustic waves. The proposed solution has the distinct advantage of extreme optical simplicity and robustness thus opening the way to a low cost acoustic field imaging system based on mass produced laser diodes.

Development of grating-based x-ray Talbot interferometry at the advanced photon source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marathe, Shashidhara; Xiao Xianghui; Wojcik, Michael J.

2012-07-31

We report on the ongoing effort to develop hard x-ray Talbot interferometry at the Advanced Photon Source (APS), Argonne National Laboratory, USA. We describe the design of the interferometer and preliminary results obtained at 25 keV using a feather and a phantom sample lithographically fabricated of gold. We mention the future developmental goals and applications of this technique as a metrology tool for x-ray optics and beam wavefront characterization.

A portable magneto-optical trap with prospects for atom interferometry in civil engineering

NASA Astrophysics Data System (ADS)

Hinton, A.; Perea-Ortiz, M.; Winch, J.; Briggs, J.; Freer, S.; Moustoukas, D.; Powell-Gill, S.; Squire, C.; Lamb, A.; Rammeloo, C.; Stray, B.; Voulazeris, G.; Zhu, L.; Kaushik, A.; Lien, Y.-H.; Niggebaum, A.; Rodgers, A.; Stabrawa, A.; Boddice, D.; Plant, S. R.; Tuckwell, G. W.; Bongs, K.; Metje, N.; Holynski, M.

2017-06-01

The high precision and scalable technology offered by atom interferometry has the opportunity to profoundly affect gravity surveys, enabling the detection of features of either smaller size or greater depth. While such systems are already starting to enter into the commercial market, significant reductions are required in order to reach the size, weight and power of conventional devices. In this article, the potential for atom interferometry based gravimetry is assessed, suggesting that the key opportunity resides within the development of gravity gradiometry sensors to enable drastic improvements in measurement time. To push forward in realizing more compact systems, techniques have been pursued to realize a highly portable magneto-optical trap system, which represents the core package of an atom interferometry system. This can create clouds of 107 atoms within a system package of 20 l and 10 kg, consuming 80 W of power. This article is part of the themed issue 'Quantum technology for the 21st century'.

A portable magneto-optical trap with prospects for atom interferometry in civil engineering

PubMed Central

Perea-Ortiz, M.; Winch, J.; Briggs, J.; Freer, S.; Moustoukas, D.; Powell-Gill, S.; Squire, C.; Lamb, A.; Rammeloo, C.; Stray, B.; Voulazeris, G.; Zhu, L.; Kaushik, A.; Lien, Y.-H.; Niggebaum, A.; Rodgers, A.; Stabrawa, A.; Boddice, D.; Plant, S. R.; Tuckwell, G. W.; Bongs, K.; Metje, N.; Holynski, M.

2017-01-01

The high precision and scalable technology offered by atom interferometry has the opportunity to profoundly affect gravity surveys, enabling the detection of features of either smaller size or greater depth. While such systems are already starting to enter into the commercial market, significant reductions are required in order to reach the size, weight and power of conventional devices. In this article, the potential for atom interferometry based gravimetry is assessed, suggesting that the key opportunity resides within the development of gravity gradiometry sensors to enable drastic improvements in measurement time. To push forward in realizing more compact systems, techniques have been pursued to realize a highly portable magneto-optical trap system, which represents the core package of an atom interferometry system. This can create clouds of 107 atoms within a system package of 20 l and 10 kg, consuming 80 W of power. This article is part of the themed issue ‘Quantum technology for the 21st century’. PMID:28652493

A portable magneto-optical trap with prospects for atom interferometry in civil engineering.

PubMed

Hinton, A; Perea-Ortiz, M; Winch, J; Briggs, J; Freer, S; Moustoukas, D; Powell-Gill, S; Squire, C; Lamb, A; Rammeloo, C; Stray, B; Voulazeris, G; Zhu, L; Kaushik, A; Lien, Y-H; Niggebaum, A; Rodgers, A; Stabrawa, A; Boddice, D; Plant, S R; Tuckwell, G W; Bongs, K; Metje, N; Holynski, M

2017-08-06

The high precision and scalable technology offered by atom interferometry has the opportunity to profoundly affect gravity surveys, enabling the detection of features of either smaller size or greater depth. While such systems are already starting to enter into the commercial market, significant reductions are required in order to reach the size, weight and power of conventional devices. In this article, the potential for atom interferometry based gravimetry is assessed, suggesting that the key opportunity resides within the development of gravity gradiometry sensors to enable drastic improvements in measurement time. To push forward in realizing more compact systems, techniques have been pursued to realize a highly portable magneto-optical trap system, which represents the core package of an atom interferometry system. This can create clouds of 10 7 atoms within a system package of 20 l and 10 kg, consuming 80 W of power.This article is part of the themed issue 'Quantum technology for the 21st century'. © 2017 The Author(s).

Accessing High Spatial Resolution in Astronomy Using Interference Methods

NASA Astrophysics Data System (ADS)

Carbonel, Cyril; Grasset, Sébastien; Maysonnave, Jean

2018-04-01

In astronomy, methods such as direct imaging or interferometry-based techniques (Michelson stellar interferometry for example) are used for observations. A particular advantage of interferometry is that it permits greater spatial resolution compared to direct imaging with a single telescope, which is limited by diffraction owing to the aperture of the instrument as shown by Rueckner et al. in a lecture demonstration. The focus of this paper, addressed to teachers and/or students in high schools and universities, is to easily underline both an application of interferometry in astronomy and stress its interest for resolution. To this end very simple optical experiments are presented to explain all the concepts. We show how an interference pattern resulting from the combined signals of two telescopes allows us to measure the distance between two stars with a resolution beyond the diffraction limit. Finally this work emphasizes the breathtaking resolution obtained in state-of-the-art instruments such as the VLTi (Very Large Telescope interferometer).

Moiré phase-shifted fiber Bragg gratings in polymer optical fibers

NASA Astrophysics Data System (ADS)

Min, Rui; Marques, Carlos; Bang, Ole; Ortega, Beatriz

2018-03-01

We demonstrate a simple way to fabricate phase-shifted fiber Bragg grating in polymer optical fibers as a narrowband transmission filter for a variety of applications at telecom wavelengths. The filters have been fabricated by overlapping two uniform fiber Bragg gratings with slightly different periods to create a Moiré grating with only two pulses (one pulse is 15 ns) of UV power. Experimental characterization of the filter is provided under different conditions where the strain and temperature sensitivities were measured.

Demonstration of the Wide-Field Imaging Interferometer Testbed Using a Calibrated Hyperspectral Image Projector

NASA Technical Reports Server (NTRS)

Bolcar, Matthew R.; Leisawitz, David; Maher, Steve; Rinehart, Stephen

2012-01-01

The Wide-field Imaging Interferometer testbed (WIIT) at NASA's Goddard Space Flight Center uses a dual-Michelson interferometric technique. The WIIT combines stellar interferometry with Fourier-transform interferometry to produce high-resolution spatial-spectral data over a large field-of-view. This combined technique could be employed on future NASA missions such as the Space Infrared Interferometric Telescope (SPIRIT) and the Sub-millimeter Probe of the Evolution of Cosmic Structure (SPECS). While both SPIRIT and SPECS would operate at far-infrared wavelengths, the WIIT demonstrates the dual-interferometry technique at visible wavelengths. The WIIT will produce hyperspectral image data, so a true hyperspectral object is necessary. A calibrated hyperspectral image projector (CHIP) has been constructed to provide such an object. The CHIP uses Digital Light Processing (DLP) technology to produce customized, spectrally-diverse scenes. CHIP scenes will have approximately 1.6-micron spatial resolution and the capability of . producing arbitrary spectra in the band between 380 nm and 1.6 microns, with approximately 5-nm spectral resolution. Each pixel in the scene can take on a unique spectrum. Spectral calibration is achieved with an onboard fiber-coupled spectrometer. In this paper we describe the operation of the CHIP. Results from the WIIT observations of CHIP scenes will also be presented.

Experimental investigations of elastohydrodynamic lubrication

NASA Technical Reports Server (NTRS)

Hamrock, B. J.; Dowson, D.

1983-01-01

Various experimental studies of elastohydrodynamic lubrication have been reviewed. The various types of machines used in these investigations, such as the disc, two and four ball, crossed-cylinders, and crossed-axes rolling disc machine, are described. The measurement of the most important parameters, such as film shape, film thickness, pressure, temperature, and traction, is considered. Determination of the film thickness is generally the most important of these effects since it dictates the extent to which the asperities on opposing surfaces can come into contact and thus has a direct bearing on wear and fatigue failure of the contacting surfaces. Several different techniques for measuring film thickness have been described, including electrical resistance, capacitance, X-ray, optical interferometry, laser beam diffraction, strain gage, and spring dynamometer methods. An attempt has been made to describe the basic concepts and limitations of each of these techniques. These various methods have been used by individual researchers, but there is no universally acceptable technique for measuring elastohydrodynamic film thickness. Capacitance methods have provided most of the reliable data for nominal line or rectangular conjunctions, but optical interferometry has proved to be the most effective procedure for elliptical contacts. Optical interferometry has the great advantage that it reveals not only the film thickness, but also details of the film shape over the complete area of the conjunction.

Holographic Interferometry and Image Analysis for Aerodynamic Testing

DTIC Science & Technology

1980-09-01

tunnels, (2) development of automated image analysis techniques for reducing quantitative flow-field data from holographic interferograms, and (3...investigation and development of software for the application of digital image analysis to other photographic techniques used in wind tunnel testing.

A novel type of very long baseline astronomical intensity interferometer

NASA Astrophysics Data System (ADS)

Borra, Ermanno F.

2013-12-01

This article presents a novel type of very long baseline astronomical interferometer that uses the fluctuations, as a function of time, of the intensity measured by a quadratic detector, which is a common type of astronomical detector. The theory on which the technique is based is validated by laboratory experiments. Its outstanding principal advantages comes from the fact that the angular structure of an astronomical object is simply determined from the visibility of the minima of the spectrum of the intensity fluctuations measured by the detector, as a function of the frequency of the fluctuations, while keeping the spacing between mirrors constant. This would allow a simple setup capable of high angular resolutions because it could use an extremely large baseline. Another major interest is that it allows for a more efficient use of telescope time because observations at a single baseline are sufficient, while amplitude and intensity interferometers need several observations at different baselines. The fact that one does not have to move the telescopes would also allow detecting faster time variations because having to move the telescopes sets a lower limit to the time variations that can be detected. The technique uses wave interaction effects and thus has some characteristics in common with intensity interferometry. A disadvantage of the technique, like in intensity interferometry, is that it needs strong sources if observing at high frequencies (e.g. the visible). This is a minor disadvantage in the radio region. At high frequencies, this disadvantage is mitigated by the fact that, like in intensity interferometry, the requirements of the optical quality of the mirrors used are far less severe than in amplitude interferometry so that poor quality large reflectors (e.g. Cherenkov telescopes) can be used in the optical region.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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)more » 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 by a dc method rather than by an electromagnetic method, i.e., holographic interferometry with applications of EIS, i.e., ac method. As a result, erroneous measurements were recorded due to the introduction of heat to Fe oxide-hydroxides.« less

Recent advances in phase shifted time averaging and stroboscopic interferometry

NASA Astrophysics Data System (ADS)

Styk, Adam; Józwik, Michał

2016-08-01

Classical Time Averaging and Stroboscopic Interferometry are widely used for MEMS/MOEMS dynamic behavior investigations. Unfortunately both methods require an extensive measurement and data processing strategies in order to evaluate the information on maximum amplitude at a given load of vibrating object. In this paper the modified strategies of data processing in both techniques are introduced. These modifications allow for fast and reliable calculation of searched value, without additional complication of measurement systems. Through the paper the both approaches are discussed and experimentally verified.

Random sequences generation through optical measurements by phase-shifting interferometry

NASA Astrophysics Data System (ADS)

François, M.; Grosges, T.; Barchiesi, D.; Erra, R.; Cornet, A.

2012-04-01

The development of new techniques for producing random sequences with a high level of security is a challenging topic of research in modern cryptographics. The proposed method is based on the measurement by phase-shifting interferometry of the speckle signals of the interaction between light and structures. We show how the combination of amplitude and phase distributions (maps) under a numerical process can produce random sequences. The produced sequences satisfy all the statistical requirements of randomness and can be used in cryptographic schemes.

Application Of Holographic Interferometry For Investigation Of Microroughness Of Engineering Surfaces

NASA Astrophysics Data System (ADS)

Lech, Marek; Mruk, Irena; Stupnicki, Jacek

1985-01-01

The paper describes an improved immersion method of holographic interferometry /IMHI/ adjusted for studies of roughness of engineering surfaces. Special optical arrangement, with two types of immersion cells and adequate technique of preparing transparent replicas reproducting with high fidelity details of differently machined surfaces was elaborated. It permits to obtain the contour maps of the surface asperities with intervals between the planes of succesive contour lines within a range of 1 μm. The results obtained for some engineering surfaces are given.

Visualization of flows in a motored rotary combustion engine using holographic interferometry

NASA Technical Reports Server (NTRS)

Hicks, Y. R.; Schock, H. J.; Craig, J. E.; Umstatter, H. L.; Lee, D. Y.

1986-01-01

The use of holographic interferometry to view the small- and large-scale flow field structures in the combustion chamber of a motored Wankel engine assembly is described. In order that the flow patterns of interest could be observed, small quantities of helium were injected with the intake air. Variation of the air flow patterns with engine speed, helium flow rate, and rotor position are described. The air flow at two locations within the combustion chamber was examined using this technique.

Amplitude and phase measurements based on low-coherence interferometry with acousto-optic spectral image filtration

NASA Astrophysics Data System (ADS)

Machikhin, Alexander; Burmak, Ludmila; Pozhar, Vitold

2018-04-01

The manuscript addresses the advantages and possible applications of acousto-optic image spectral filtration in lowcoherence interferometry. In particular, an effective operation of acousto-optical tunable filters in combination with Michelson-type interferometers is shown. The results of original experiments are presented. It is demonstrated that amplitude and phase spatial distributions of light waves reflected from or transmitted through the object can be fast determined in contactless manner for any spectral intervals with use of the presented techniques.

Stress analysis and damage evaluation of flawed composite laminates by hybrid-numerical methods

NASA Technical Reports Server (NTRS)

Yang, Yii-Ching

1992-01-01

Structural components in flight vehicles is often inherited flaws, such as microcracks, voids, holes, and delamination. These defects will degrade structures the same as that due to damages in service, such as impact, corrosion, and erosion. It is very important to know how a structural component can be useful and survive after these flaws and damages. To understand the behavior and limitation of these structural components researchers usually do experimental tests or theoretical analyses on structures with simulated flaws. However, neither approach has been completely successful. As Durelli states that 'Seldom does one method give a complete solution, with the most efficiency'. Examples of this principle is seen in photomechanics which additional strain-gage testing can only average stresses at locations of high concentration. On the other hand, theoretical analyses including numerical analyses are implemented with simplified assumptions which may not reflect actual boundary conditions. Hybrid-Numerical methods which combine photomechanics and numerical analysis have been used to correct this inefficiency since 1950's. But its application is limited until 1970's when modern computer codes became available. In recent years, researchers have enhanced the data obtained from photoelasticity, laser speckle, holography and moire' interferometry for input of finite element analysis on metals. Nevertheless, there is only few of literature being done on composite laminates. Therefore, this research is dedicated to this highly anisotropic material.

An evaluation of the Iosipescu specimen for composite materials shear property measurement

NASA Technical Reports Server (NTRS)

Morton, J.; Ho, H.; Tsai, M. Y.; Farley, G. L.

1992-01-01

A detailed evaluation of the suitability of the Iosipescu specimen tested in the modified Wyoming fixture is presented. A linear finite element model of the specimen is used to assess the uniformity of the shear stress field in the vicinity of the notch, and demonstrate the effect of the nonuniform stress field upon strain gage measurements used for the determination of composite shear moduli. Based upon test results from graphite-epoxy laminates, the proximity of the load introduction point to the test section and the material orthotropy greatly influence the individual gage readings, however, shear modulus determination is not significantly affected by the lack of pure shear. Correction factors are needed to allow for the nonuniformity of the strain field and the use of the average shear stress in the shear modulus evaluation. The correction factors are determined for the region occupied by the strain gage rosette. A comparison of the strain gage readings from one surface of a specimen with corresponding data from moire interferometry on the opposite face documented an extreme sensitivity of some fiber orientations to eccentric loading which induced twisting and spurious shear stress-strain curves. The discovery of specimen twisting explains the apparently inconsistent shear property data found in the literature. Recommendations for improving the reliability and accuracy of the shear modulus values are made, and the implications for shear strength measurement discussed.

Multiple hot-carrier collection in photo-excited graphene Moiré superlattices

PubMed Central

Wu, Sanfeng; Wang, Lei; Lai, You; Shan, Wen-Yu; Aivazian, Grant; Zhang, Xian; Taniguchi, Takashi; Watanabe, Kenji; Xiao, Di; Dean, Cory; Hone, James; Li, Zhiqiang; Xu, Xiaodong

2016-01-01

In conventional light-harvesting devices, the absorption of a single photon only excites one electron, which sets the standard limit of power-conversion efficiency, such as the Shockley-Queisser limit. In principle, generating and harnessing multiple carriers per absorbed photon can improve efficiency and possibly overcome this limit. We report the observation of multiple hot-carrier collection in graphene/boron-nitride Moiré superlattice structures. A record-high zero-bias photoresponsivity of 0.3 A/W (equivalently, an external quantum efficiency exceeding 50%) is achieved using graphene’s photo-Nernst effect, which demonstrates a collection of at least five carriers per absorbed photon. We reveal that this effect arises from the enhanced Nernst coefficient through Lifshtiz transition at low-energy Van Hove singularities, which is an emergent phenomenon due to the formation of Moiré minibands. Our observation points to a new means for extremely efficient and flexible optoelectronics based on van der Waals heterostructures. PMID:27386538

Measurement of Strain and Stress Distributions in Structural Materials by Electron Moiré Method

NASA Astrophysics Data System (ADS)

Kishimoto, Satoshi; Xing, Yougming; Tanaka, Yoshihisa; Kagawa, Yutaka

A method for measuring the strain and stress distributions in structural materials has been introduced. Fine model grids were fabricated by electron beam lithography, and an electron beam scan by a scanning electron microscope (SEM) was used as the master grid. Exposure of the electron beam scan onto the model grid in an SEM produced the electron beam moiré fringes of bright and dark parts caused by the different amounts of the secondary electrons per a primary electron. For demonstration, the micro-creep deformation of pure copper was observed. The creep strain distribution and the grain boundary sliding were analyzed. The residual strain and stress at the interface between a fiber and a matrix of a fiber reinforced plastic (FRP) were measured using the pushing-out test and this electron moiré method. Also, a non-uniform deformation around the boundary of 3-point bended laminated steel was observed and the strain distribution analyzed.

Magic C60 islands forming due to moiré interference between islands and substrate

NASA Astrophysics Data System (ADS)

Olyanich, D. A.; Mararov, V. V.; Utas, T. V.; Utas, O. A.; Gruznev, D. V.; Zotov, A. V.; Saranin, A. A.

2015-05-01

Recently proposed mechanism for self-organized formation of magic islands [Nat.Comm. 4(2013)1679] has received a new experimental confirmation. According to this mechanism, self-assembly is mediated by the moiré interference between an island and underlying substrate lattice. It was first detected at C60 island growth on In-adsorbed Si(111)√{ 3} ×√{ 3}-Au surface. Changing In adsorbate for Tl results in lowering the corrugations of the surface potential relief due to a greater surface metallization. This allows formation of the C60 arrays with novel moiré pattern. As a result, a new set of magic C60 islands is formed on Tl-adsorbed Au/Si(111) surface differing from that observed on In-adsorbed surface. For example, the 19-C60 magic island which has a non-compact boomerang shape on In-adsorbed Au/Si(111) surfaces adopts a shape of a regular hexagon on Tl-adsorbed surface.

Holographic evaluation of fatigue cracks by a compressive stress (HYSTERESIS) technique

NASA Technical Reports Server (NTRS)

Freska, S. A.; Rummel, W. D.

1974-01-01

Holographic interferometry compares unknown field of optical waves with known one. Differences are displayed as interference bands or fringes. Technique was evaluated on fatigue-cracked 2219-T87 aluminum-alloy panels. Small cracks were detected when specimen was incrementally unloaded.

Single-shot Z eff dense plasma diagnostic through simultaneous refraction and attenuation measurements with a Talbot–Lau x-ray moiré deflectometer

DOE PAGES

Valdivia, M. P.; Stutman, D.; Finkenthal, M.

2015-03-23

The Talbot–Lau x-ray moiré deflectometer is a powerful plasma diagnostic capable of delivering simultaneous refraction and attenuation information through the accurate detection of x-ray phase shift and intensity. The diagnostic can provide the index of refraction n=1₋δ + iβ of an object (dense plasma, for example) placed in the x-ray beam by independently measuring both δ and β, which are directly related to the electron density n e and the attenuation coefficient μ respectively. Since δ and β depend on the effective atomic number Z eff, a map can be obtained from the ratio between phase and absorption images acquiredmore » in a single shot. The Talbot–Lau x-ray moiré deflectometer and its corresponding data acquisition and processing are briefly described to illustrate how the above is achieved; Z eff values of test objects within the 4₋12 range were obtained experimentally through simultaneous refraction and attenuation measurements. We show that Z eff mapping of objects does not require previous knowledge of sample length or shape. In conclusion, the determination of Z eff from refraction and attenuation measurements with moiré deflectometry could be of high interest to various domains of high energy density research, such as shocked materials and inertial confinement fusion experiments, as well as material science and nondestructive testing.« less

Single-shot Z eff dense plasma diagnostic through simultaneous refraction and attenuation measurements with a Talbot–Lau x-ray moiré deflectometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valdivia, M. P.; Stutman, D.; Finkenthal, M.

The Talbot–Lau x-ray moiré deflectometer is a powerful plasma diagnostic capable of delivering simultaneous refraction and attenuation information through the accurate detection of x-ray phase shift and intensity. The diagnostic can provide the index of refraction n=1₋δ + iβ of an object (dense plasma, for example) placed in the x-ray beam by independently measuring both δ and β, which are directly related to the electron density n e and the attenuation coefficient μ respectively. Since δ and β depend on the effective atomic number Z eff, a map can be obtained from the ratio between phase and absorption images acquiredmore » in a single shot. The Talbot–Lau x-ray moiré deflectometer and its corresponding data acquisition and processing are briefly described to illustrate how the above is achieved; Z eff values of test objects within the 4₋12 range were obtained experimentally through simultaneous refraction and attenuation measurements. We show that Z eff mapping of objects does not require previous knowledge of sample length or shape. In conclusion, the determination of Z eff from refraction and attenuation measurements with moiré deflectometry could be of high interest to various domains of high energy density research, such as shocked materials and inertial confinement fusion experiments, as well as material science and nondestructive testing.« less

New optical tomographic & topographic techniques for biomedical applications

NASA Astrophysics Data System (ADS)

Buytaert, Jan

The mammalian middle ear contains the eardrum and the three auditory ossicles, and forms an impedance match between sound in air and pressure waves in the fluid of the inner ear. Without this intermediate system, with its unsurpassed efficiency and dynamic range, we would be practically deaf. Physics-based modeling of this extremely complex mechanical system is necessary to help our basic understanding of the functioning of hearing. Highly realistic models will make it possible to predict the outcome of surgical interventions and to optimize design of ossicle prostheses and active middle ear implants. To obtain such models and with realistic output, basic input data is still missing. In this dissertation I developed and used two new optical techniques to obtain two essential sets of data: accurate three-dimensional morphology of the middle ear structures, and elasticity parameters of the eardrum. The first technique is a new method for optical tomography of macroscopic biomedical objects, which makes it possible to measure the three-dimensional geometry of the middle ear ossicles and soft tissues which are connecting and suspending them. I made a new and high-resolution version of this orthogonal-plane fluorescence optical sectioning method, to obtain micrometer resolution in macroscopic specimens. The result is thus a complete 3-D model of the middle (and inner) ear of gerbil in unprecedented quality. On top of high-resolution morphological models of the middle ear structures, I applied the technique in other fields of research as well. The second device works according to a new optical profilometry technique which allows to measure shape and deformations of the eardrum and other membranes or objects. The approach is called projection moire profilometry, and creates moire interference fringes which contain the height information. I developed a setup which uses liquid crystal panels for grid projection and optical demodulation. Hence no moving parts are present and the setup is entirely digitally controlled. This measurement method is developed to determine the elasticity parameters of the eardrum in-situ. Other surface shapes however can also be measured.

Multi Temporal Interferometry as Tool for Urban Landslide Hazard Assessment

NASA Astrophysics Data System (ADS)

Vicari, A.; Colangelo, G.; Famiglietti, N.; Cecere, G.; Stramondo, S.; Viggiano, D.

2017-12-01

Advanced Synthetic Aperture Radar Differential Interferometry (A-DInSAR) are Multi Temporal Interferometry(MTI) techniques suitable for the monitoring of deformation phenomena in slow kinematics. A-DInSAR methodologies include both Coherence-based type, as well as Small Baseline Subset (SBAS) (Berardino et al., 2002, Lanari et al., 2004) and Persistent/Permanent Scatterers (PS), (Ferretti et al., 2001). Such techniques are capable to provide wide-area coverage (thousands of km2) and precise (mm-cm resolution), spatially dense information (from hundreds to thousands of measurementpoints/km2) on groundsurfacedeformations. SBAS and PShavebeenapplied to the town of Stigliano (MT) in Basilicata Region (Southern Italy), where the social center has been destroyed after the reactivation of a known landslide. The comparison of results has shown that these techniques are equivalent in terms of obtained coherent areas and displacement patterns, although lightly different velocity values for individual points (-5/-25 mm/y for PS vs. -5/-15 mm/y for SBAS) have been pointed out. Differences are probably due to scattering properties of the ground surface (e.g. Lauknes et al., 2010). Furthermore, on the crown of the landslide body, a Robotics Explorer Total Monitoring Station (Leica Nova TM50) that measures distance values with 0.6 mm of resolution has been installed. In particular, 20 different points corresponding to that identified through satellite techniques have been chosen, and a sampling time of 15 minutes has been fixed. The displacement values obtained are in agreement with the results of the MTI analysis, showing as these techniques could be a useful tool in the case of early - warning situations.

Holographic interferometry applied to the measurement of displacements of the interior points of transparent bodies.

PubMed

Sciammarella, C A; Gilbert, J A

1976-09-01

Utilizing the light scattering property of transparent media, holographic interferometry is applied to the measurement of displacement at the interior planes of three dimensional bodies. The use of a double beam illumination and the introduction of a fictitious displacement make it feasible to obtain information corresponding to components of displacement projected on the scattering plane. When the proposed techniques are invoked, it is possible to eliminate the use of a matching index of refraction fluid in many problems involving symmetrically loaded prismatic bodies. Scattered light holographic interferometry is limited in its use to small changes in the index of refraction and to low values of relative retardation. In spite of these restrictions, a large number of technical problems in both statics and dynamics can be solved.

Optical interferometry and Gaia parallaxes for a robust calibration of the Cepheid distance scale

NASA Astrophysics Data System (ADS)

Kervella, Pierre; Mérand, Antoine; Gallenne, Alexandre; Trahin, Boris; Borgniet, Simon; Pietrzynski, Grzegorz; Nardetto, Nicolas; Gieren, Wolfgang

2018-04-01

We present the modeling tool we developed to incorporate multi-technique observations of Cepheids in a single pulsation model: the Spectro-Photo-Interferometry of Pulsating Stars (SPIPS). The combination of angular diameters from optical interferometry, radial velocities and photometry with the coming Gaia DR2 parallaxes of nearby Galactic Cepheids will soon enable us to calibrate the projection factor of the classical Parallax-of-Pulsation method. This will extend its applicability to Cepheids too distant for accurate Gaia parallax measurements, and allow us to precisely calibrate the Leavitt law's zero point. As an example application, we present the SPIPS model of the long-period Cepheid RS Pup that provides a measurement of its projection factor, using the independent distance estimated from its light echoes.

Application of SPM interferometry in MEMS vibration measurement

NASA Astrophysics Data System (ADS)

Tang, Chaowei; He, Guotian; Xu, Changbiao; Zhao, Lijuan; Hu, Jun

2007-12-01

The resonant frequency measurement of cantilever has an important position in MEMS(Micro Electro Mechanical Systems) research. Meanwhile the SPM interferometry is a high-precision optical measurement technique, which can be used in physical quantity measurement of vibration, displacement, surface profile. Hence, in this paper we propose to apply SPM(SPM) interferometry in measuring the vibration of MEMS cantilever and in the experiment the vibration of MEMS cantilever was driven by light source. Then this kind of vibration was measured in nm precision. Finally the relational characteristics of MEMS cantilever vibration under optical excitation can be gotten and the measurement principle is analyzed. This method eliminates the influence on the measuring precision caused by external interference and light intensity change through feedback control loop. Experiment results prove that this measurement method has a good effect.

Phase-Sensitive Surface Plasmon Resonance Sensors: Recent Progress and Future Prospects

PubMed Central

Deng, Shijie; Wang, Peng; Yu, Xinglong

2017-01-01

Surface plasmon resonance (SPR) is an optical sensing technique that is capable of performing real-time, label-free and high-sensitivity monitoring of molecular interactions. SPR biosensors can be divided according to their operating principles into angle-, wavelength-, intensity- and phase-interrogated devices. With their complex optical configurations, phase-interrogated SPR sensors generally provide higher sensitivity and throughput, and have thus recently emerged as prominent biosensing devices. To date, several methods have been developed for SPR phase interrogation, including heterodyne detection, polarimetry, shear interferometry, spatial phase modulation interferometry and temporal phase modulation interferometry. This paper summarizes the fundamentals of phase-sensitive SPR sensing, reviews the available methods for phase interrogation of these sensors, and discusses the future prospects for and trends in the development of this technology. PMID:29206182

Multi-function optical characterization and inspection of MEMS components using stroboscopic coherence scanning interferometry

NASA Astrophysics Data System (ADS)

Tapilouw, Abraham Mario; Chen, Liang-Chia; Xuan-Loc, Nguyen; Chen, Jin-Liang

2014-08-01

A Micro-electro-mechanical-system (MEMS) is a widely used component in many industries, including energy, biotechnology, medical, communications, and automotive industries. However, effective inspection systems are also needed to ensure the functional reliability of MEMS. This study developed a stroboscopic coherence scanning Interferometry (SCSI) technique for measuring key characteristics typically used as criteria in MEMS inspections. Surface profiles of MEMS both static and dynamic conditions were measured by means of coherence scanning Interferometry (CSI). Resonant frequencies of vibrating MEMS were measured by deformation of interferogram fringes for out-of-plane vibration and by image correlation for in-plane vibration. The measurement bandwidth of the developed system can be tuned up to three megahertz or higher for both in-plane and out-of-plane measurement of MEMS.

Volcano deformation--Geodetic monitoring techniques

USGS Publications Warehouse

Dzurisin, Daniel; Lu, Zhong

2007-01-01

This book describes the techniques used by volcanologists to successfully predict several recent volcanic eruptions by combining information from various scientific disciplines, including geodetic techniques. Many recent developments in the use of state-of-the-art and emerging techniques, including Global Positioning System and Synthetic Aperture Radar Interferometry, mean that most books on volcanology are out of date, and this book includes chapters devoted entirely to these two techniques.

Water vapor - The wet blanket of microwave interferometry

NASA Technical Reports Server (NTRS)

Resch, G. M.

1980-01-01

The various techniques that utilize microwave interferometry could be employed to determine distances of several thousand kilometers with an accuracy of 1 cm or 2 cm. Such measurements would be useful to obtain new knowledge of earth dynamics, greater insight into fundamental astronomical constants, and the ability to accurately navigate a spacecraft in interplanetary flight. There is, however, a basic problem, related to the presence of tropospheric water vapor, which has to be overcome before such measurements can be realized. Differing amounts of water vapor over the interferometer stations cause errors in the differential time of arrival which is the principal observable quantity. Approaches for overcoming this problem are considered, taking into account requirements for water vapor calibration to support interferometric techniques.

Protein-ligand interactions investigated by thermal shift assays (TSA) and dual polarization interferometry (DPI).

PubMed

Grøftehauge, Morten K; Hajizadeh, Nelly R; Swann, Marcus J; Pohl, Ehmke

2015-01-01

Over the last decades, a wide range of biophysical techniques investigating protein-ligand interactions have become indispensable tools to complement high-resolution crystal structure determinations. Current approaches in solution range from high-throughput-capable methods such as thermal shift assays (TSA) to highly accurate techniques including microscale thermophoresis (MST) and isothermal titration calorimetry (ITC) that can provide a full thermodynamic description of binding events. Surface-based methods such as surface plasmon resonance (SPR) and dual polarization interferometry (DPI) allow real-time measurements and can provide kinetic parameters as well as binding constants. DPI provides additional spatial information about the binding event. Here, an account is presented of new developments and recent applications of TSA and DPI connected to crystallography.

Protein–ligand interactions investigated by thermal shift assays (TSA) and dual polarization interferometry (DPI)

PubMed Central

Grøftehauge, Morten K.; Hajizadeh, Nelly R.; Swann, Marcus J.; Pohl, Ehmke

2015-01-01

Over the last decades, a wide range of biophysical techniques investigating protein–ligand interactions have become indispensable tools to complement high-resolution crystal structure determinations. Current approaches in solution range from high-throughput-capable methods such as thermal shift assays (TSA) to highly accurate techniques including microscale thermophoresis (MST) and isothermal titration calorimetry (ITC) that can provide a full thermodynamic description of binding events. Surface-based methods such as surface plasmon resonance (SPR) and dual polarization interferometry (DPI) allow real-time measurements and can provide kinetic parameters as well as binding constants. DPI provides additional spatial information about the binding event. Here, an account is presented of new developments and recent applications of TSA and DPI connected to crystallography. PMID:25615858

Medium and Small Aperture Speckle Interferometry for Geostationary On-Orbit-Servicing Space Surveillance

NASA Astrophysics Data System (ADS)

Scott, R.

On-Orbit-Servicing (OOS) in Geostationary Equatorial Orbit (GEO) is likely to become a space mission reality provoking new problems for the optical space surveillance community. OOS’ close-proximity flight of servicer and client satellites with separations less than 1 kilometer in GEO challenge the metric measurement capabilities of medium and small aperture space surveillance instruments. This paper describes an OOS monitoring technique based on Cross-Spectrum speckle interferometry to compensate for atmospheric turbulence and measure the OOS satellites’ differential relative position. Cross-Spectrum speckle interferometry, an astronomical technique developed to measure the astrometric positions of binary stars, was adapted to the geostationary OOS problem and was tested using Sloan i’ observations of co-located geostationary satellites. Medium (1.6m) and small (0.35m) aperture telescopes were used to observe these satellites undergoing optical conjunctions where their apparent line-of-sight separation narrowed within 5 arcseconds. During the initial development of the Cross-Spectrum approach some weaknesses were identified where particle strikes, faint background stars, anomalous fringe orientation angles and high relative angular rates corrupt the relative position measurement process. In this paper, newly adjusted compensation techniques to remedy these issues are described and the data is reprocessed. The Cross-Spectrum’s performance is shown to work well on closely-spaced GEO satellites with separations less than 3 arcseconds and evidence is shown suggesting the technique can measure satellite separations within 1.8 arcseconds.

Pressure sensor to determine spatial pressure distributions on boundary layer flows

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Piroozan, Parham; Corke, Thomas C.

1997-03-01

The determination of pressures along the surface of a wind tunnel proves difficult with methods that must introduce devices into the flow stream. This paper presents a sensor that is part of the wall. A special interferometric reflection moire technique is developed and used to produce signals that measures pressure both in static and dynamic settings. The sensor developed is an intelligent sensor that combines optics and electronics to analyze the pressure patterns. The sensor provides the input to a control system that is capable of modifying the shape of the wall and preserve the stability of the flow.

Dynamic speckle interferometry of microscopic processes in solid state and thin biological objects

NASA Astrophysics Data System (ADS)

Vladimirov, A. P.

2015-08-01

Modernized theory of dynamic speckle interferometry is considered. It is shown that the time-average radiation intensity has the parameters characterizing the wave phase changes. It also brings forward an expression for time autocorrelation function of the radiation intensity. It is shown that with the vanishing averaging time value the formulas transform to the prior expressions. The results of experiments with high-cycle material fatigue and cell metabolism analysis conducted using the time-averaging technique are discussed. Good reproducibility of the results is demonstrated. It is specified that the upgraded technique allows analyzing accumulation of fatigue damage, detecting the crack start moment and determining its growth velocity with uninterrupted cyclic load. It is also demonstrated that in the experiments with a cell monolayer the technique allows studying metabolism change both in an individual cell and in a group of cells.

Quantitative phase imaging using four interferograms with special phase shifts by dual-wavelength in-line phase-shifting interferometry

NASA Astrophysics Data System (ADS)

Xu, Xiaoqing; Wang, Yawei; Ji, Ying; Xu, Yuanyuan; Xie, Ming; Han, Hao

2018-05-01

A new approach of quantitative phase imaging using four interferograms with special phase shifts in dual-wavelength in-line phase-shifting interferometry is presented. In this method, positive negative 2π phase shifts are employed to easily separate the incoherent addition of two single-wavelength interferograms by combining the phase-shifting technique with the subtraction procedure, then the quantitative phase at one of both wavelengths can be achieved based on two intensities without the corresponding dc terms by the use of the character of the trigonometric function. The quantitative phase of the other wavelength can be retrieved from two dc-term suppressed intensities obtained by employing the two-step phase-shifting technique or the filtering technique in the frequency domain. The proposed method is illustrated with theory, and its effectiveness is demonstrated by simulation experiments of the spherical cap and the HeLa cell, respectively.

Very-long-baseline interferometry techniques applied to problems of geodesy, geophysics, planetary science, astronomy, and general relativity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Counselman, C.C. III

1973-09-01

Very-long-baseline interferometry (VLBI) techniques have already been used to determine the vector separations between antennas thousands of kilometers apart to within 2 m and the directions of extragalactic radio sources to 0.1'', and to track an artificial satellite of the earth and the Apollo Lunar Rover on the surface of the Moon. The relative loostions of the Apollo Lunar Surface Experiment Package (ALSEP) transmitters on the lunar surface are being measured within 1 m, and the Moon's libration is being messured to 1'' of selenocentric src. Attempts are under way to measure the solar gravitational deflection of radio waves moremore » accurately than previously possible, by means of VLBI. A wide variety of scientific problems is being attacked by VLBI techniques, which may soon be two orders of magnitude more accurate than at present. (auth)« less

Heterodyne-detected dispersed vibrational echo spectroscopy.

PubMed

Jones, Kevin C; Ganim, Ziad; Tokmakoff, Andrei

2009-12-24

We develop heterodyned dispersed vibrational echo spectroscopy (HDVE) and demonstrate the new capabilities in biophysical applications. HDVE is a robust ultrafast technique that provides a characterization of the real and imaginary components of third-order nonlinear signals with high sensitivity and single-laser-shot capability and can be used to extract dispersed pump-probe and dispersed vibrational echo spectra. Four methods for acquiring HDVE phase and amplitude spectra were compared: Fourier transform spectral interferometry, a new phase modulation spectral interferometry technique, and combination schemes. These extraction techniques were demonstrated in the context of protein amide I spectroscopy. Experimental HDVE and heterodyned free induction decay amide I spectra were explicitly compared to conventional dispersed pump-probe, dispersed vibrational echo, and absorption spectra. The new capabilities of HDVE were demonstrated by acquiring single-shot spectra and melting curves of ubiquitin and concentration-dependent spectra of insulin suitable for extracting the binding constant for dimerization. The introduced techniques will prove particularly useful in transient experiments, studying irreversible reactions, and micromolar concentration studies of small proteins.

Polarization interferometry for real-time spectroscopic plasmonic sensing.

PubMed

Otto, Lauren M; Mohr, Daniel A; Johnson, Timothy W; Oh, Sang-Hyun; Lindquist, Nathan C

2015-03-07

We present quantitative, spectroscopic polarization interferometry phase measurements on plasmonic surfaces for sensing applications. By adding a liquid crystal variable wave plate in our beam path, we are able to measure phase shifts due to small refractive index changes on the sensor surface. By scanning in a quick sequence, our technique is extended to demonstrate real-time measurements. While this optical technique is applicable to different sensor geometries-e.g., nanoparticles, nanogratings, or nanoapertures-the plasmonic sensors we use here consist of an ultrasmooth gold layer with buried linear gratings. Using these devices and our phase measurement technique, we calculate a figure of merit that shows improvement over measuring only surface plasmon resonance shifts from a reflected intensity spectrum. To demonstrate the general-purpose versatility of our phase-resolved measurements, we also show numerical simulations with another common device architecture: periodic plasmonic slits. Since our technique inherently measures both the intensity and phase of the reflected or transmitted light simultaneously, quantitative sensor device characterization is possible.

Temperature-insensitive refractive index sensor based on tilted moiré FBG with high resolution.

PubMed

Wang, Tao; Liu, Kun; Jiang, Junfeng; Xue, Meng; Chang, Pengxiang; Liu, Tiegen

2017-06-26

We proposed and fabricated a tilted moiré FBG (TMFBG), whose grating section was made up of two consecutive scribed TFBGs. By adjusting the Bragg wavelengths and the tilt angles of the two TFBGs, the two cladding mode combs of the transmission spectrum are non-overlapped. When the TMFBG was used for refractive index detection, its resolution can reach 2 × 10 -7 RIU, which is an order of magnitude higher than that of a single TFBG. And this result also has a good performance of temperature-insensitivity.

Nature of the optical information recorded in speckles

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.

1998-09-01

The process of encoding displacement information in electronic Holographic Interferometry is reviewed. Procedures to extend the applicability of this technique to large deformations are given. The proposed techniques are applied and results from these experiments are compared with results obtained by other means. The similarity between the two sets of results illustrates the validity for the new techniques.

Performance analysis of an integrated GPS/inertial attitude determination system. M.S. Thesis - MIT

NASA Technical Reports Server (NTRS)

Sullivan, Wendy I.

1994-01-01

The performance of an integrated GPS/inertial attitude determination system is investigated using a linear covariance analysis. The principles of GPS interferometry are reviewed, and the major error sources of both interferometers and gyroscopes are discussed and modeled. A new figure of merit, attitude dilution of precision (ADOP), is defined for two possible GPS attitude determination methods, namely single difference and double difference interferometry. Based on this figure of merit, a satellite selection scheme is proposed. The performance of the integrated GPS/inertial attitude determination system is determined using a linear covariance analysis. Based on this analysis, it is concluded that the baseline errors (i.e., knowledge of the GPS interferometer baseline relative to the vehicle coordinate system) are the limiting factor in system performance. By reducing baseline errors, it should be possible to use lower quality gyroscopes without significantly reducing performance. For the cases considered, single difference interferometry is only marginally better than double difference interferometry. Finally, the performance of the system is found to be relatively insensitive to the satellite selection technique.

Optical monitoring of protein crystal growth

NASA Technical Reports Server (NTRS)

Choudry, A.

1988-01-01

The possibility of using various optical techniques for detecting the onset of nucleation in protein crystal growth was investigated. Direct microscopy, general metrologic techniques, light scattering, ultraviolet absorption, and interferometry are addressed along with techniques for determining pH value. The necessity for collecting basic data on the optical properties of the growth solution as a prerequisite to the evaluation of monitoring techniques is pointed out.

Stitching interferometry of a full cylinder without using overlap areas

NASA Astrophysics Data System (ADS)

Peng, Junzheng; Chen, Dingfu; Yu, Yingjie

2017-08-01

Traditional stitching interferometry requires finding out the overlap correspondence and computing the discrepancies in the overlap regions, which makes it complex and time-consuming to obtain the 360° form map of a cylinder. In this paper, we develop a cylinder stitching model based on a new set of orthogonal polynomials, termed Legendre Fourier (LF) polynomials. With these polynomials, individual subaperture data can be expanded as a composition of the inherent form of a partial cylinder surface and additional misalignment parameters. Then the 360° form map can be acquired by simultaneously fitting all subaperture data with the LF polynomials. A metal shaft was measured to experimentally verify the proposed method. In contrast to traditional stitching interferometry, our technique does not require overlapping of adjacent subapertures, thus significantly reducing the measurement time and making the stitching algorithm simple.

Nanoscale optical interferometry with incoherent light

PubMed Central

Li, Dongfang; Feng, Jing; Pacifici, Domenico

2016-01-01

Optical interferometry has empowered an impressive variety of biosensing and medical imaging techniques. A widely held assumption is that devices based on optical interferometry require coherent light to generate a precise optical signature in response to an analyte. Here we disprove that assumption. By directly embedding light emitters into subwavelength cavities of plasmonic interferometers, we demonstrate coherent generation of surface plasmons even when light with extremely low degrees of spatial and temporal coherence is employed. This surprising finding enables novel sensor designs with cheaper and smaller light sources, and consequently increases accessibility to a variety of analytes, such as biomarkers in physiological fluids, or even airborne nanoparticles. Furthermore, these nanosensors can now be arranged along open detection surfaces, and in dense arrays, accelerating the rate of parallel target screening used in drug discovery, among other high volume and high sensitivity applications. PMID:26880171

Relative astrometry of compact flaring structures in Sgr A* with polarimetric very long baseline interferometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Michael D.; Doeleman, Sheperd S.; Fish, Vincent L.

2014-10-20

We demonstrate that polarimetric interferometry can be used to extract precise spatial information about compact polarized flares of Sgr A*. We show that, for a faint dynamical component, a single interferometric baseline suffices to determine both its polarization and projected displacement from the quiescent intensity centroid. A second baseline enables two-dimensional reconstruction of the displacement, and additional baselines can self-calibrate using the flare, enhancing synthesis imaging of the quiescent emission. We apply this technique to simulated 1.3 mm wavelength observations of a 'hot spot' embedded in a radiatively inefficient accretion disk around Sgr A*. Our results indicate that, even withmore » current sensitivities, polarimetric interferometry with the Event Horizon Telescope can achieve ∼5 μas relative astrometry of compact flaring structures near Sgr A* on timescales of minutes.« less

Nanoscale optical interferometry with incoherent light.

PubMed

Li, Dongfang; Feng, Jing; Pacifici, Domenico

2016-02-16

Optical interferometry has empowered an impressive variety of biosensing and medical imaging techniques. A widely held assumption is that devices based on optical interferometry require coherent light to generate a precise optical signature in response to an analyte. Here we disprove that assumption. By directly embedding light emitters into subwavelength cavities of plasmonic interferometers, we demonstrate coherent generation of surface plasmons even when light with extremely low degrees of spatial and temporal coherence is employed. This surprising finding enables novel sensor designs with cheaper and smaller light sources, and consequently increases accessibility to a variety of analytes, such as biomarkers in physiological fluids, or even airborne nanoparticles. Furthermore, these nanosensors can now be arranged along open detection surfaces, and in dense arrays, accelerating the rate of parallel target screening used in drug discovery, among other high volume and high sensitivity applications.

Advances in the application of holography for NDE

NASA Astrophysics Data System (ADS)

Sciammarella, C. A.

1985-01-01

The basic methodology of holographic interferometry in nondestructive testing (NDT) applications are described. Applications to crack detection in ceramic materials, including a crack 50 microns deep in a turbine blade, are discussed in detail. The theoretical principles of holographic interferometry are explained, and a general description of a holographic interferometric recording system is given. A nondestructive interferometric technique for measuring the gradual erosion of calcareous stones exposed to acid rain is also presented. Detailed line drawings illustrating the hologram recording and interferometric fringe pattern analysis elements in an interferometric holographic NDT device are provided.

The application of infrared speckle interferometry to the imaging of remote galaxies and AGN

NASA Technical Reports Server (NTRS)

Olivares, Robert O.

1995-01-01

A 1.5 meter reflector, used for both infrared and optical astronomy, is also being used for infrared speckle interferometry and CCD imaging. The application of these imaging techniques to remote galaxies and active galactic nuclei are discussed. A simple model for the origin of speckle in coherent imaging systems is presented. Very careful photometry of the continuum of the galaxy M31 is underway using CCD images. It involves extremely intensive data reduction because the object itself is very large and has low surface brightness.

Classical analogues of two-photon quantum interference.

PubMed

Kaltenbaek, R; Lavoie, J; Resch, K J

2009-06-19

Chirped-pulse interferometry (CPI) captures the metrological advantages of quantum Hong-Ou-Mandel (HOM) interferometry in a completely classical system. Modified HOM interferometers are the basis for a number of seminal quantum-interference effects. Here, the corresponding modifications to CPI allow for the first observation of classical analogues to the HOM peak and quantum beating. They also allow a new classical technique for generating phase super-resolution exhibiting a coherence length dramatically longer than that of the laser light, analogous to increased two-photon coherence lengths in entangled states.

Three-dimensional surface deformation mapping by convensional interferometry and multiple aperture interferometry

USGS Publications Warehouse

Jung, H.-S.; Lu, Z.; Lee, C.-W.

2011-01-01

Interferometric synthetic aperture radar (InSAR) technique has been successfully used for mapping surface deformations [1-2], but it has been normally limited to a measurement along the radar line-of-sight (LOS) direction. For this reason, it is impossible to determine the north (N-S) component of surface deformation because of using data from near-polar orbiting satellites, and it is not sufficient to resolve the parameters of models for earthquakes and volcanic activities because there is a marked trade-off among model parameters [3]. ?? 2011 KIEES.

Status of the LISA On Table experiment: a electro-optical simulator for LISA

NASA Astrophysics Data System (ADS)

Laporte, M.; Halloin, H.; Bréelle, E.; Buy, C.; Grüning, P.; Prat, P.

2017-05-01

The LISA project is a space mission that aim at detecting gravitational waves in space. An electro-optical simulator called LISA On Table (LOT) is being developed at APC in order to test noise reduction techniques (such as Timed Delayed Interferometry) and instruments that will be used. This document presents its latest results: TimeDelayed Interferometry of 1st generation works in the case of a simulated white noise with static, unequal arms. Future and ongoing developments of the experiment are also addressed.

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

PubMed Central

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. PMID:21280906

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

PubMed Central

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

Noninvasive evaluation system of fractured bone based on speckle interferometry

NASA Astrophysics Data System (ADS)

Yamanada, Shinya; Murata, Shigeru; Tanaka, Yohsuke

2010-11-01

This paper presents a noninvasive evaluation system of fractured bone based on speckle interferometry using a modified evaluation index for higher performance, and the experiments are carried out to examine the feasibility in evaluating bone fracture healing and the influence of some system parameters on the performance. From experimental results, it is shown that the presence of fractured part of bone and the state of bone fracture healing are successfully estimated by observing fine speckle fringes on the object surface. The proposed evaluation index also can successfully express the difference between the cases with cut and without it. Since most system parameters are found not to affect the performance of the present technique, the present technique is expected to be applied to various patients that have considerable individual variability.

Cost-Effective Magnetoencephalography Based on Time Encoded Optical Fiber Interferometry for Epilepsy and Tinnitus

DTIC Science & Technology

2016-09-01

Thanks to the elegant reciprocal geometry of the Sagnac interferometer, many sources of drift that would present in other polarimetry techniques were...interferometers. And is 2 orders of magnitude better than competing polarimetry -based Faraday techniques. Couple a Rb Vapor cell to the Sagnac interferometer

Probing electric and magnetic fields with a Moiré deflectometer

NASA Astrophysics Data System (ADS)

Lansonneur, P.; Bräunig, P.; Demetrio, A.; Müller, S. R.; Nedelec, P.; Oberthaler, M. K.

2017-08-01

A new contact-free approach for measuring simultaneously electric and magnetic field is reported, which considers the use of a low energy ion source, a set of three transmission gratings and a position sensitive detector. Recently tested with antiprotons (Aghion et al., 2014) [1] at the CERN Antiproton Decelerator facility, this paper extends the proof of principle of a moiré deflectometer (Oberthaler et al., 1996) [2] for distinguishing electric from magnetic fields and opens the route to precision measurements when one is not limited by the ion source intensity. The apparatus presented, whose resolution is mainly limited by the shot noise is able to measure fields as low as 9 mVm-1 Hz-1/2 for electric component and 100 μG Hz-1/2 for the magnetic component. Scaled to 100 nm pitch for the gratings, accessible with current state-of-the-art technology [3], the moiré fieldmeter would be able to measure fields as low as 22 μVm-1 Hz-1/2 and 0.2 μG Hz-1/2.

Application of Extended Kalman Filter in Persistant Scatterer Interferometry to Enhace the Accuracy of Unwrapping Process

NASA Astrophysics Data System (ADS)

Tavakkoli Estahbanat, A.; Dehghani, M.

2017-09-01

In interferometry technique, phases have been modulated between 0-2π. Finding the number of integer phases missed when they were wrapped is the main goal of unwrapping algorithms. Although the density of points in conventional interferometry is high, this is not effective in some cases such as large temporal baselines or noisy interferograms. Due to existing noisy pixels, not only it does not improve results, but also it leads to some unwrapping errors during interferogram unwrapping. In PS technique, because of the sparse PS pixels, scientists are confronted with a problem to unwrap phases. Due to the irregular data separation, conventional methods are sterile. Unwrapping techniques are divided in to path-independent and path-dependent in the case of unwrapping paths. A region-growing method which is a path-dependent technique has been used to unwrap PS data. In this paper an idea of EKF has been generalized on PS data. This algorithm is applied to consider the nonlinearity of PS unwrapping problem as well as conventional unwrapping problem. A pulse-pair method enhanced with singular value decomposition (SVD) has been used to estimate spectral shift from interferometric power spectral density in 7*7 local windows. Furthermore, a hybrid cost-map is used to manage the unwrapping path. This algorithm has been implemented on simulated PS data. To form a sparse dataset, A few points from regular grid are randomly selected and the RMSE of results and true unambiguous phases in presented to validate presented approach. The results of this algorithm and true unwrapped phases were completely identical.

Radio Occultation Experiments with Venus Express and Mars Express using the Planetary Radio Interferometry and Doppler Experiment (PRIDE) Technique

NASA Astrophysics Data System (ADS)

Bocanegra Bahamon, T.; Gurvits, L.; Molera Calves, G.; Cimo, G.; Duev, D.; Pogrebenko, S.; Dirkx, D.; Rosenblatt, P.

2017-12-01

The Planetary Radio Interferometry and Doppler Experiment (PRIDE) is a technique that can be used to enhance multiple radio science experiments of planetary missions. By 'eavesdropping' on the spacecraft signal using radio telescopes from different VLBI networks around the world, the PRIDE technique provides precise open-loop Doppler and VLBI observables to able to reconstruct the spacecraft's orbit. The application of this technique for atmospheric studies has been assessed by observing ESA's Venus Express (VEX) and Mars Express (MEX) during multiple Venus and Mars occultation events between 2012 and 2014. From these observing sessions density, temperature and pressure profiles of Venus and Mars neutral atmosphere and ionosphere have been retrieved. We present an error propagation analysis where the uncertainties of the atmospheric properties measured with this technique have been derived. These activities serve as demonstration of the applicability of the PRIDE technique for radio occultation studies, and provides a benchmark against the traditional Doppler tracking provided by the NASA's DSN and ESA's Estrack networks for these same purposes, in the framework of the upcoming ESA JUICE mission to the Jovian system.

Telescope for x ray and gamma ray studies in astrophysics

NASA Technical Reports Server (NTRS)

Weaver, W. D.; Desai, Upendra D.

1993-01-01

Imaging of x-rays has been achieved by various methods in astrophysics, nuclear physics, medicine, and material science. A new method for imaging x-ray and gamma-ray sources avoids the limitations of previously used imaging devices. Images are formed in optical wavelengths by using mirrors or lenses to reflect and refract the incoming photons. High energy x-ray and gamma-ray photons cannot be reflected except at grazing angles and pass through lenses without being refracted. Therefore, different methods must be used to image x-ray and gamma-ray sources. Techniques using total absorption, or shadow casting, can provide images in x-rays and gamma-rays. This new method uses a coder made of a pair of Fresnel zone plates and a detector consisting of a matrix of CsI scintillators and photodiodes. The Fresnel zone plates produce Moire patterns when illuminated by an off-axis source. These Moire patterns are deconvolved using a stepped sine wave fitting or an inverse Fourier transform. This type of coder provides the capability of an instantaneous image with sub-arcminute resolution while using a detector with only a coarse position-sensitivity. A matrix of the CsI/photodiode detector elements provides the necessary coarse position-sensitivity. The CsI/photodiode detector also allows good energy resolution. This imaging system provides advantages over previously used imaging devices in both performance and efficiency.

Measurement of strains at high temperatures by means of a portable holographic moire camera

NASA Astrophysics Data System (ADS)

Sciammarella, C. A.; Bhat, G.; Shao, Y.

Electronic holographic moire is utilized to measure strains at temperatures up to 1000 C. A CW laser operating at 50 mW and at the wavelength of 632.8 nm is used to illuminate the objects under study. The main variables influencing the fringe patterns visibility are discussed and measurements are performed to obtain the values of these variables in the performed experiments. The coefficient of expansion of an alloy is measured at temperatures ranging from 797 C to 986 C. Excellent agreement is found between the measured values and those provided by the manufacturer.

Measurement of strains at high temperatures by means of a portable holographic moire camera

NASA Technical Reports Server (NTRS)

Sciammarella, C. A.; Bhat, G.; Shao, Y.

1989-01-01

Electronic holographic moire is utilized to measure strains at temperatures up to 1000 C. A CW laser operating at 50 mW and at the wavelength of 632.8 nm is used to illuminate the objects under study. The main variables influencing the fringe patterns visibility are discussed and measurements are performed to obtain the values of these variables in the performed experiments. The coefficient of expansion of an alloy is measured at temperatures ranging from 797 C to 986 C. Excellent agreement is found between the measured values and those provided by the manufacturer.

Comparison of phase unwrapping algorithms for topography reconstruction based on digital speckle pattern interferometry

NASA Astrophysics Data System (ADS)

Li, Yuanbo; Cui, Xiaoqian; Wang, Hongbei; Zhao, Mengge; Ding, Hongbin

2017-10-01

Digital speckle pattern interferometry (DSPI) can diagnose the topography evolution in real-time, continuous and non-destructive, and has been considered as a most promising technique for Plasma-Facing Components (PFCs) topography diagnostic under the complicated environment of tokamak. It is important for the study of digital speckle pattern interferometry to enhance speckle patterns and obtain the real topography of the ablated crater. In this paper, two kinds of numerical model based on flood-fill algorithm has been developed to obtain the real profile by unwrapping from the wrapped phase in speckle interference pattern, which can be calculated through four intensity images by means of 4-step phase-shifting technique. During the process of phase unwrapping by means of flood-fill algorithm, since the existence of noise pollution, and other inevitable factors will lead to poor quality of the reconstruction results, this will have an impact on the authenticity of the restored topography. The calculation of the quality parameters was introduced to obtain the quality-map from the wrapped phase map, this work presents two different methods to calculate the quality parameters. Then quality parameters are used to guide the path of flood-fill algorithm, and the pixels with good quality parameters are given priority calculation, so that the quality of speckle interference pattern reconstruction results are improved. According to the comparison between the flood-fill algorithm which is suitable for speckle pattern interferometry and the quality-guided flood-fill algorithm (with two different calculation approaches), the errors which caused by noise pollution and the discontinuous of the strips were successfully reduced.

Advanced Differential Radar Interferometry (A-DInSAR) as integrative tool for a structural geological analysis

NASA Astrophysics Data System (ADS)

Crippa, B.; Calcagni, L.; Rossi, G.; Sternai, P.

2009-04-01

Advanced Differential SAR interferometry (A-DInSAR) is a technique monitoring large-coverage surface deformations using a stack of interferograms generated from several complex SLC SAR images, acquired over the same target area at different times. In this work are described the results of a procedure to calculate terrain motion velocity on highly correlated pixels (E. Biescas, M. Crosetto, M. Agudo, O. Monserrat e B. Crippa: Two Radar Interferometric Approaches to Monitor Slow and Fast Land Deformation, 2007) in two area Gemona - Friuli, Northern Italy, Pollino - Calabria, Southern Italy, and, furthermore, are presented some consideration, based on successful examples of the present analysis. The choice of these pixels whose displacement velocity is calculated depends on the dispersion index value (DA) or using coherence values along the stack interferograms. A-DInSAR technique allows to obtain highly reliable velocity values of the vertical displacement. These values concern the movement of minimum surfaces of about 80m2 at the maximum resolution and the minimum velocity that can be recognized is of the order of mm/y. Because of the high versatility of the technology, because of the large dimensions of the area that can be analyzed (of about 10000Km2) and because of the high precision and reliability of the results obtained, we think it is possible to exploit radar interferometry to obtain some important information about the structural context of the studied area, otherwise very difficult to recognize. Therefore we propose radar interferometry as a valid investigation tool whose results must be considered as an important integration of the data collected in fieldworks.

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.

Atom Interferometry for Detection of Gravitational Waves: Progress and Prospects

NASA Astrophysics Data System (ADS)

Hogan, Jason

2015-04-01

Gravitational wave astronomy promises to provide a new window into the universe, collecting information about astrophysical systems and cosmology that is difficult or impossible to acquire by other methods. Detector designs based on atom interferometry offer a number of advantages over traditional approaches, including access to conventionally inaccessible frequency ranges and substantially reduced antenna baselines. Atomic physics techniques also make it possible to build a gravitational wave detector with a single linear baseline, potentially offering advantages in cost and design flexibility. In support of these proposals, recent progress in long baseline atom interferometry has enabled observation of matter wave interference with atomic wavepacket separations exceeding 10 cm and interferometer durations of more than 2 seconds. These results are obtained in a 10-meter drop tower incorporating large momentum transfer atom optics. This approach can provide ground-based proof-of-concept demonstrations of many of the technical requirements of both terrestrial and satellite gravitational wave detectors.

Interferometry on a Balloon; Paving the Way for Space-based Interferometers

NASA Technical Reports Server (NTRS)

Rinehart, Stephen A.

2008-01-01

Astronomical studies at infrared wavelengths have dramatically improved our understanding of the universe, and observations with Spitzer, the upcoming Herschel mission, and SOFIA will continue to provide exciting new discoveries. The relatively low angular resolution of these missions, however, is insufficient to resolve the physical scale on which mid-to-far-infrared emission arises, resulting in source and structure ambiguities that limit our ability to answer key science questions. Interferometry enables high angular resolution at these wavelengths- a powerful tool for scientific discovery. We will build the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII), an eight-meter baseline Michelson stellar interferometer to fly on a high-altitude balloon. BETTII's spectral-spatial capability, provided by an instrument using double-Fourier techniques, will address key questions about the nature of disks in young star clusters and active galactic nuclei and the envelopes of evolved stars. BETTII will also lay the technological groundwork for future space interferometers.

The Balloon Experimental Twin Telescope for Infrared Interferometry

NASA Technical Reports Server (NTRS)

Rinehart, Stephen A.

2008-01-01

Astronomical studies at infrared wavelengths have dramatically improved our understanding of the universe, and observations with Spitzer, the upcoming Herschel mission, and SOFIA will continue to provide exciting new discoveries. The relatively low angular resolution of these missions, however, is insufficient to resolve the physical scales on which mid- to far-infrared emission arises, resulting in source and structure ambiguities that limit our ability to answer key science questions. Interferometry enables high angular resolution at these wavelengths, a powerful tool for scientific discovery, We will build the Balloon Experimental Twin Telescope for Infrared Interferometry (BETII), an eight-meter baseline Michelson stellar interferometer to fly on a high-altitude balloon. BETTII's spectral-spatial capability, provided by an instrument using double-Fourier techniques, will address key questions about the nature of disks in young star clusters and active galactic nuclei and the envelopes of evolved stars. BETTII will also lay the technological groundwork for future space interferometers,

Analysis of surface structures of chemically peculiar stars with modern and future interferometers

NASA Astrophysics Data System (ADS)

Shulyak, D.; Perraut, K.; Paladini, Claudia; Li Causi, G.; Sacuto, Stephane; Kochukhov, O.

2014-07-01

Interferometry is a very powerful observational technique known in astronomy for many decades. Its application to main-sequence stars, however, is still limited to only brightest objects. In this work we aim to explore the application of interferometry to a special class of main-sequence stars known as chemically peculiar (CP) stars. These stars demonstrate surface chemical abundance inhomogeneities (spots) that usually cover a considerable part of the stellar surface and induce a pronounced spectral and photometric variability. Interferometry thus has a potential to naturally resolve such spots in single stars, providing unique complementary information about spots sizes and contrasts. By means of numerical experiments we derive the actual interferometric requirements essential for the CP stars research that can be addressed in future instrument development. The first comparison between theoretical predictions and already available observations will also be discussed.

Applications of wavelets in interferometry and artificial vision

NASA Astrophysics Data System (ADS)

Escalona Z., Rafael A.

2001-08-01

In this paper we present a different point of view of phase measurements performed in interferometry, image processing and intelligent vision using Wavelet Transform. In standard and white-light interferometry, the phase function is retrieved by using phase-shifting, Fourier-Transform, cosinus-inversion and other known algorithms. Our novel technique presented here is faster, robust and shows excellent accuracy in phase determinations. Finally, in our second application, fringes are no more generate by some light interaction but result from the observation of adapted strip set patterns directly printed on the target of interest. The moving target is simply observed by a conventional vision system and usual phase computation algorithms are adapted to an image processing by wavelet transform, in order to sense target position and displacements with a high accuracy. In general, we have determined that wavelet transform presents properties of robustness, relative speed of calculus and very high accuracy in phase computations.

Equations of Motion of a Ground Moving Target for a Multi-Channel Spaceborne SAR

DTIC Science & Technology

2009-03-01

Canada as represented by the Minister of National Defence, 2009 c© Sa Majesté la Reine (en droit du Canada), telle que représentée par le ministre de...ex., RADARSAT- 2 ou TerraSAR-X). Les travaux menant au présent mémoire technique visaient à dériver un ensemble d’équations de mouvement d’une cible...Dragos̆ević ; DRDC Ottawa TM 2008-326 ; R & D pour la défense Canada – Ottawa ; mars 2009. Introduction : Le traitement des données des radars à synthèse

Improved self-reliance shearing interferometric technique for collimation testing

NASA Astrophysics Data System (ADS)

Zhao, Mingshan; Li, Guohua; Wang, Zhaobing; Jing, Yaling; Li, Yi

1995-06-01

Self-reference single plate shearing interferometric technique used for collimation testing of light beams are briefly reviewed. Two improved configurations of this self-reference interferometry with an inclined screen and matched half-field interferograms are described in detail. Sensitivity of these configurations is analyzed and compared with that of the existing ones.

Spectral domain phase microscopy: a new tool for measuring cellular dynamics and cytoplasmic flow

NASA Astrophysics Data System (ADS)

McDowell, Emily J.; Choma, Michael A.; Ellerbee, Audrey K.; Izatt, Joseph A.

2005-03-01

Broadband interferometry is an attractive technique for the detection of cellular motions because it provides depth-resolved interferometric phase information via coherence gating. Here a phase sensitive technique called spectral domain phase microscopy (SDPM) is presented. SDPM is a functional extension of spectral domain optical coherence tomography that allows for the detection of cellular motions and dynamics with nanometer-scale sensitivity. This sensitivity is made possible by the inherent phase stability of spectral domain OCT combined with common-path interferometry. The theory that underlies this technique is presented, the sensitivity of the technique is demonstrated by the measurement of the thermal expansion coefficient of borosilicate glass, and the response of an Amoeba proteus to puncture of its cell membrane is measured. We also exploit the phase stability of SDPM to perform Doppler flow imaging of cytoplasmic streaming in A. proteus. We show reversal of cytoplasmic flow in response to stimuli, and we show that the cytoplasmic flow is laminar (i.e. parabolic) in nature. We are currently investigating the use of SDPM in a variety of different cell types.

Ideal-observer detectability in photon-counting differential phase-contrast imaging using a linear-systems approach

PubMed Central

Fredenberg, Erik; Danielsson, Mats; Stayman, J. Webster; Siewerdsen, Jeffrey H.; Åslund, Magnus

2012-01-01

Purpose: To provide a cascaded-systems framework based on the noise-power spectrum (NPS), modulation transfer function (MTF), and noise-equivalent number of quanta (NEQ) for quantitative evaluation of differential phase-contrast imaging (Talbot interferometry) in relation to conventional absorption contrast under equal-dose, equal-geometry, and, to some extent, equal-photon-economy constraints. The focus is a geometry for photon-counting mammography. Methods: Phase-contrast imaging is a promising technology that may emerge as an alternative or adjunct to conventional absorption contrast. In particular, phase contrast may increase the signal-difference-to-noise ratio compared to absorption contrast because the difference in phase shift between soft-tissue structures is often substantially larger than the absorption difference. We have developed a comprehensive cascaded-systems framework to investigate Talbot interferometry, which is a technique for differential phase-contrast imaging. Analytical expressions for the MTF and NPS were derived to calculate the NEQ and a task-specific ideal-observer detectability index under assumptions of linearity and shift invariance. Talbot interferometry was compared to absorption contrast at equal dose, and using either a plane wave or a spherical wave in a conceivable mammography geometry. The impact of source size and spectrum bandwidth was included in the framework, and the trade-off with photon economy was investigated in some detail. Wave-propagation simulations were used to verify the analytical expressions and to generate example images. Results: Talbot interferometry inherently detects the differential of the phase, which led to a maximum in NEQ at high spatial frequencies, whereas the absorption-contrast NEQ decreased monotonically with frequency. Further, phase contrast detects differences in density rather than atomic number, and the optimal imaging energy was found to be a factor of 1.7 higher than for absorption contrast. Talbot interferometry with a plane wave increased detectability for 0.1-mm tumor and glandular structures by a factor of 3–4 at equal dose, whereas absorption contrast was the preferred method for structures larger than ∼0.5 mm. Microcalcifications are small, but differ from soft tissue in atomic number more than density, which is favored by absorption contrast, and Talbot interferometry was barely beneficial at all within the resolution limit of the system. Further, Talbot interferometry favored detection of “sharp” as opposed to “smooth” structures, and discrimination tasks by about 50% compared to detection tasks. The technique was relatively insensitive to spectrum bandwidth, whereas the projected source size was more important. If equal photon economy was added as a restriction, phase-contrast efficiency was reduced so that the benefit for detection tasks almost vanished compared to absorption contrast, but discrimination tasks were still improved close to a factor of 2 at the resolution limit. Conclusions: Cascaded-systems analysis enables comprehensive and intuitive evaluation of phase-contrast efficiency in relation to absorption contrast under requirements of equal dose, equal geometry, and equal photon economy. The benefit of Talbot interferometry was highly dependent on task, in particular detection versus discrimination tasks, and target size, shape, and material. Requiring equal photon economy weakened the benefit of Talbot interferometry in mammography. PMID:22957600

Three recipes for improving the image quality with optical long-baseline interferometers: BFMC, LFF, and DPSC

NASA Astrophysics Data System (ADS)

Millour, Florentin A.; Vannier, Martin; Meilland, Anthony

2012-07-01

We present here three recipes for getting better images with optical interferometers. Two of them, Low- Frequencies Filling and Brute-Force Monte Carlo were used in our participation to the Interferometry Beauty Contest this year and can be applied to classical imaging using V2 and closure phases. These two addition to image reconstruction provide a way of having more reliable images. The last recipe is similar in its principle as the self-calibration technique used in radio-interferometry. We call it also self-calibration, but it uses the wavelength-differential phase as a proxy of the object phase to build-up a full-featured complex visibility set of the observed object. This technique needs a first image-reconstruction run with an available software, using closure-phases and squared visibilities only. We used it for two scientific papers with great success. We discuss here the pros and cons of such imaging technique.

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

PubMed

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

2015-01-01

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.

Urban Monitoring Based on SENTINEL-1 Data Using Permanent Scatterer Interferometry and SAR Tomography

NASA Astrophysics Data System (ADS)

Crosetto, M.; Budillon, A.; Johnsy, A.; Schirinzi, G.; Devanthéry, N.; Monserrat, O.; Cuevas-González, M.

2018-04-01

A lot of research and development has been devoted to the exploitation of satellite SAR images for deformation measurement and monitoring purposes since Differential Interferometric Synthetic Apertura Radar (InSAR) was first described in 1989. In this work, we consider two main classes of advanced DInSAR techniques: Persistent Scatterer Interferometry and Tomographic SAR. Both techniques make use of multiple SAR images acquired over the same site and advanced procedures to separate the deformation component from the other phase components, such as the residual topographic component, the atmospheric component, the thermal expansion component and the phase noise. TomoSAR offers the advantage of detecting either single scatterers presenting stable proprieties over time (Persistent Scatterers) and multiple scatterers interfering within the same range-azimuth resolution cell, a significant improvement for urban areas monitoring. This paper addresses a preliminary inter-comparison of the results of both techniques, for a test site located in the metropolitan area of Barcelona (Spain), where interferometric Sentinel-1 data were analysed.

Far infrared diagnostics of electron concentration in combustion MHD plasmas using interferometry and Faraday rotation

NASA Astrophysics Data System (ADS)

Kuzmenko, P. J.

1985-12-01

The plasma electrical conductivity is a key parameter in determining the efficiency of an magnetohydrodynamic (MHD) generator. Electromagnetic waves offer an accurate, non-intrusive probe. The electron concentration and mobility may be deduced from the refractive index and absorption coefficient measured with an interferometer. The first experiment used an HCOOH laser at 393.6 microns feeding a Michelson interferometer mounted around a combustor duct with open ports. Simultaneous measurements of positive ion density and plasma temperature made with a Langmuir probe and line reversal apparatus verified the operation of the interferometer. With a magnetic field present, measurement of the polarization rotation and induced ellipticity in a wave traveling along the field provides information on the plasma conductivity. Compared to interferometry, diagnostic apparatus based on Faraday rotation offers simpler optics and requires far less stringent mechanical stability at a cost of lower sensitivity. An advanced detection scheme, using a polarizing beam splitter improved the sensitivity to be comparable to that of interferometry. Interferometry is the preferred technique for small scale, high accuracy measurements, with Faraday rotation reserved for large systems or measurements within a working generator.

The application of satellite differential SAR interferometry-derived ground displacements in hydrogeology

USGS Publications Warehouse

Galloway, D.L.; Hoffmann, J.

2007-01-01

The application of satellite differential synthetic aperture radar (SAR) interferometry, principally coherent (InSAR) and to a lesser extent, persistent-scatterer (PSI) techniques to hydrogeologic studies has improved capabilities to map, monitor, analyze, and simulate groundwater flow, aquifer-system compaction and land subsidence. A number of investigations over the previous decade show how the spatially detailed images of ground displacements measured with InSAR have advanced hydrogeologic understanding, especially when a time series of images is used in conjunction with histories of changes in water levels and management practices. Important advances include: (1) identifying structural or lithostratigraphic boundaries (e.g. faults or transitional facies) of groundwater flow and deformation; (2) defining the material and hydraulic heterogeneity of deforming aquifer-systems; (3) estimating system properties (e.g. storage coefficients and hydraulic conductivities); and (4) constraining numerical models of groundwater flow, aquifer-system compaction, and land subsidence. As a component of an integrated approach to hydrogeologic monitoring and characterization of unconsolidated alluvial groundwater basins differential SAR interferometry contributes unique information that can facilitate improved management of groundwater resources. Future satellite SAR missions specifically designed for differential interferometry will enhance these contributions. ?? Springer-Verlag 2006.

Differential tracking data types for accurate and efficient Mars planetary navigation

NASA Technical Reports Server (NTRS)

Edwards, C. D., Jr.; Kahn, R. D.; Folkner, W. M.; Border, J. S.

1991-01-01

Ways in which high-accuracy differential observations of two or more deep space vehicles can dramatically extend the power of earth-based tracking over conventional range and Doppler tracking are discussed. Two techniques - spacecraft-spacecraft differential very long baseline interferometry (S/C-S/C Delta(VLBI)) and same-beam interferometry (SBI) - are discussed. The tracking and navigation capabilities of conventional range, Doppler, and quasar-relative Delta(VLBI) are reviewed, and the S/C-S/C Delta (VLBI) and SBI types are introduced. For each data type, the formation of the observable is discussed, an error budget describing how physical error sources manifest themselves in the observable is presented, and potential applications of the technique for Space Exploration Initiative scenarios are examined. Requirements for spacecraft and ground systems needed to enable and optimize these types of observations are discussed.

Advanced image based methods for structural integrity monitoring: Review and prospects

NASA Astrophysics Data System (ADS)

Farahani, Behzad V.; Sousa, Pedro José; Barros, Francisco; Tavares, Paulo J.; Moreira, Pedro M. G. P.

2018-02-01

There is a growing trend in engineering to develop methods for structural integrity monitoring and characterization of in-service mechanical behaviour of components. The fast growth in recent years of image processing techniques and image-based sensing for experimental mechanics, brought about a paradigm change in phenomena sensing. Hence, several widely applicable optical approaches are playing a significant role in support of experiment. The current review manuscript describes advanced image based methods for structural integrity monitoring, and focuses on methods such as Digital Image Correlation (DIC), Thermoelastic Stress Analysis (TSA), Electronic Speckle Pattern Interferometry (ESPI) and Speckle Pattern Shearing Interferometry (Shearography). These non-contact full-field techniques rely on intensive image processing methods to measure mechanical behaviour, and evolve even as reviews such as this are being written, which justifies a special effort to keep abreast of this progress.

Single-Shot Measurement of Temporally-Dependent Polarization State of Femtosecond Pulses by Angle-Multiplexed Spectral-Spatial Interferometry

NASA Astrophysics Data System (ADS)

Lin, Ming-Wei; Jovanovic, Igor

2016-09-01

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.

Dimensional metrology of micro structure based on modulation depth in scanning broadband light interferometry

NASA Astrophysics Data System (ADS)

Zhou, Yi; Tang, Yan; Deng, Qinyuan; Zhao, Lixin; Hu, Song

2017-08-01

Three-dimensional measurement and inspection is an area with growing needs and interests in many domains, such as integrated circuits (IC), medical cure, and chemistry. Among the methods, broadband light interferometry is widely utilized due to its large measurement range, noncontact and high precision. In this paper, we propose a spatial modulation depth-based method to retrieve the surface topography through analyzing the characteristics of both frequency and spatial domains in the interferogram. Due to the characteristics of spatial modulation depth, the technique could effectively suppress the negative influences caused by light fluctuations and external disturbance. Both theory and experiments are elaborated to confirm that the proposed method can greatly improve the measurement stability and sensitivity with high precision. This technique can achieve a superior robustness with the potential to be applied in online topography measurement.

Algorithms and Array Design Criteria for Robust Imaging in Interferometry

NASA Astrophysics Data System (ADS)

Kurien, Binoy George

Optical interferometry is a technique for obtaining high-resolution imagery of a distant target by interfering light from multiple telescopes. Image restoration from interferometric measurements poses a unique set of challenges. The first challenge is that the measurement set provides only a sparse-sampling of the object's Fourier Transform and hence image formation from these measurements is an inherently ill-posed inverse problem. Secondly, atmospheric turbulence causes severe distortion of the phase of the Fourier samples. We develop array design conditions for unique Fourier phase recovery, as well as a comprehensive algorithmic framework based on the notion of redundant-spaced-calibration (RSC), which together achieve reliable image reconstruction in spite of these challenges. Within this framework, we see that classical interferometric observables such as the bispectrum and closure phase can limit sensitivity, and that generalized notions of these observables can improve both theoretical and empirical performance. Our framework leverages techniques from lattice theory to resolve integer phase ambiguities in the interferometric phase measurements, and from graph theory, to select a reliable set of generalized observables. We analyze the expected shot-noise-limited performance of our algorithm for both pairwise and Fizeau interferometric architectures and corroborate this analysis with simulation results. We apply techniques from the field of compressed sensing to perform image reconstruction from the estimates of the object's Fourier coefficients. The end result is a comprehensive strategy to achieve well-posed and easily-predictable reconstruction performance in optical interferometry.

Measurement and prediction of the thermomechanical response of shape memory alloy hybrid composite beams

NASA Astrophysics Data System (ADS)

Davis, Brian; Turner, Travis L.; Seelecke, Stefan

2005-05-01

Previous work at NASA Langley Research Center (LaRC) involved fabrication and testing of composite beams with embedded, pre-strained shape memory alloy (SMA) ribbons within the beam structures. That study also provided comparison of experimental results with numerical predictions from a research code making use of a new thermoelastic model for shape memory alloy hybrid composite (SMAHC) structures. The previous work showed qualitative validation of the numerical model. However, deficiencies in the experimental-numerical correlation were noted and hypotheses for the discrepancies were given for further investigation. The goal of this work is to refine the experimental measurement and numerical modeling approaches in order to better understand the discrepancies, improve the correlation between prediction and measurement, and provide rigorous quantitative validation of the numerical analysis/design tool. The experimental investigation is refined by a more thorough test procedure and incorporation of higher fidelity measurements such as infrared thermography and projection moire interferometry. The numerical results are produced by a recently commercialized version of the constitutive model as implemented in ABAQUS and are refined by incorporation of additional measured parameters such as geometric imperfection. Thermal buckling, post-buckling, and random responses to thermal and inertial (base acceleration) loads are studied. The results demonstrate the effectiveness of SMAHC structures in controlling static and dynamic responses by adaptive stiffening. Excellent agreement is achieved between the predicted and measured results of the static and dynamic thermomechanical response, thereby providing quantitative validation of the numerical tool.

Measurement and Prediction of the Thermomechanical Response of Shape Memory Alloy Hybrid Composite Beams

NASA Technical Reports Server (NTRS)

Davis, Brian; Turner, Travis L.; Seelecke, Stefan

2005-01-01

Previous work at NASA Langley Research Center (LaRC) involved fabrication and testing of composite beams with embedded, pre-strained shape memory alloy (SMA) ribbons within the beam structures. That study also provided comparison of experimental results with numerical predictions from a research code making use of a new thermoelastic model for shape memory alloy hybrid composite (SMAHC) structures. The previous work showed qualitative validation of the numerical model. However, deficiencies in the experimental-numerical correlation were noted and hypotheses for the discrepancies were given for further investigation. The goal of this work is to refine the experimental measurement and numerical modeling approaches in order to better understand the discrepancies, improve the correlation between prediction and measurement, and provide rigorous quantitative validation of the numerical analysis/design tool. The experimental investigation is refined by a more thorough test procedure and incorporation of higher fidelity measurements such as infrared thermography and projection moire interferometry. The numerical results are produced by a recently commercialized version of the constitutive model as implemented in ABAQUS and are refined by incorporation of additional measured parameters such as geometric imperfection. Thermal buckling, post-buckling, and random responses to thermal and inertial (base acceleration) loads are studied. The results demonstrate the effectiveness of SMAHC structures in controlling static and dynamic responses by adaptive stiffening. Excellent agreement is achieved between the predicted and measured results of the static and dynamic thermomechanical response, thereby providing quantitative validation of the numerical tool.

Evolution in High Spatial Resolution Imaging of Faint, Complex Objects

NASA Astrophysics Data System (ADS)

van Belle, G.

The astrophysical community has been working at the task of obtaining image information of the smallest structures in the sky via the use of optical interferometry for well over a century. A richly diverse family of technology architectures has been explored over the years, and yet the current family of facilities are all striking similar. Although there may be other, heretofore undeployed, architectures that support the goal of collecting image information at the highest resolutions, we expect dramatic advances at the component level of long-baseline interferometry to be the best avenue for advancing the technique, rather than entirely new architectures.

The Wide-Field Imaging Interferometry Testbed: Recent Results

NASA Technical Reports Server (NTRS)

Rinehart, Stephen

2006-01-01

We present recent results from the Wide-Field Imaging Interferometry Testbed (WIIT). The data acquired with the WIIT is "double Fourier" data, including both spatial and spectral information within each data cube. We have been working with this data, and starting to develop algorithms, implementations, and techniques for reducing this data. Such algorithms and tools are of great importance for a number of proposed future missions, including the Space Infrared Interferometric Telescope (SPIRIT), the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS), and the Terrestrial Planet Finder Interferometer (TPF-I)/Darwin. Recent results are discussed and future study directions are described.

Interferometric fibre-optic curvature sensing for structural, directional vibration measurements

NASA Astrophysics Data System (ADS)

Kissinger, Thomas; Chehura, Edmon; James, Stephen W.; Tatam, Ralph P.

2017-06-01

Dynamic fibre-optic curvature sensing using fibre segment interferometry is demonstrated using a cost-effective rangeresolved interferometry interrogation system. Differential strain measurements from four fibre strings, each containing four fibre segments of gauge length 20 cm, allow the inference of lateral vibrations as well as the direction of the vibration of a cantilever test object. Dynamic tip displacement resolutions in the micrometre range over a 21 kHz interferometric bandwidth demonstrate the suitability of this approach for highly sensitive fibre-optic directional vibration measurements, complementing existing laser vibrometry techniques by removing the need for side access to the structure under test.

Metrology Optical Power Budgeting in SIM Using Statistical Analysis Techniques

NASA Technical Reports Server (NTRS)

Kuan, Gary M

2008-01-01

The Space Interferometry Mission (SIM) is a space-based stellar interferometry instrument, consisting of up to three interferometers, which will be capable of micro-arc second resolution. Alignment knowledge of the three interferometer baselines requires a three-dimensional, 14-leg truss with each leg being monitored by an external metrology gauge. In addition, each of the three interferometers requires an internal metrology gauge to monitor the optical path length differences between the two sides. Both external and internal metrology gauges are interferometry based, operating at a wavelength of 1319 nanometers. Each gauge has fiber inputs delivering measurement and local oscillator (LO) power, split into probe-LO and reference-LO beam pairs. These beams experience power loss due to a variety of mechanisms including, but not restricted to, design efficiency, material attenuation, element misalignment, diffraction, and coupling efficiency. Since the attenuation due to these sources may degrade over time, an accounting of the range of expected attenuation is needed so an optical power margin can be book kept. A method of statistical optical power analysis and budgeting, based on a technique developed for deep space RF telecommunications, is described in this paper and provides a numerical confidence level for having sufficient optical power relative to mission metrology performance requirements.

Deformation Studies and Elasticity Measurements of Hydrophobic Silica Aerogels using Double Exposure Holographic Interferometry

NASA Astrophysics Data System (ADS)

Chikode, Prashant; Sabale, Sandip; Chavan, Sugam

2017-01-01

Holographic interferometry is mainly used for the non-destructive testing of various materials and metals in industry, engineering and technological fields. This technique may used to study the elastic properties of materials. We have used the double exposure holographic interferometry (DEHI) to study the surface deformation and elastic constant such as Young's modulus of mechanically stressed aerogel samples. Efforts have been made in the past to use non-destructive techniques like sound velocity measurements through aerogels. Hydrophobic Silica aerogels were prepared by the sol-gel process followed by supercritical methanol drying. The molar ratio of tetramethoxysilane: methyltrimethoxysilane: H2O constant at 1.2:0.8:6 while the methanol / tetramethoxysilane molar ratio (M) was varied systematically from 14 to 20 to obtain hydrophobic silica aerogels. After applying the weights on the sample in grams, double exposure holograms of aerogel samples have been successfully recorded. Double exposure causes localization of interference fringes on the aerogel surface and these fringes are used to determine the surface deformation and elastic modulus of the aerogels and they are in good agreement with the experiments performed by using four point bending. University Grants Commission for Minor Research Project and Department of Science and Technology for FIST Program.

Moiré deflectometry using the Talbot-Lau interferometer as refraction diagnostic for High Energy Density plasmas at energies below 10 keV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valdivia, M. P.; Stutman, D.; Finkenthal, M.

2014-07-15

The highly localized density gradients expected in High Energy Density (HED) plasma experiments can be characterized by x-ray phase-contrast imaging in addition to conventional attenuation radiography. Moiré deflectometry using the Talbot-Lau grating interferometer setup is an attractive HED diagnostic due to its high sensitivity to refraction induced phase shifts. We report on the adaptation of such a system for operation in the sub-10 keV range by using a combination of free standing and ultrathin Talbot gratings. This new x-ray energy explored matches well the current x-ray backlighters used for HED experiments, while also enhancing phase effects at lower electron densities.more » We studied the performance of the high magnification, low energy Talbot-Lau interferometer, for single image phase retrieval using Moiré fringe deflectometry. Our laboratory and simulation studies indicate that such a device is able to retrieve object electron densities from phase shift measurements. Using laboratory x-ray sources from 7 to 15 μm size we obtained accurate simultaneous measurements of refraction and attenuation for both sharp and mild electron density gradients.« less

Moiré deflectometry using the Talbot-Lau interferometer as refraction diagnostic for high energy density plasmas at energies below 10 keV.

PubMed

Valdivia, M P; Stutman, D; Finkenthal, M

2014-07-01

The highly localized density gradients expected in High Energy Density (HED) plasma experiments can be characterized by x-ray phase-contrast imaging in addition to conventional attenuation radiography. Moiré deflectometry using the Talbot-Lau grating interferometer setup is an attractive HED diagnostic due to its high sensitivity to refraction induced phase shifts. We report on the adaptation of such a system for operation in the sub-10 keV range by using a combination of free standing and ultrathin Talbot gratings. This new x-ray energy explored matches well the current x-ray backlighters used for HED experiments, while also enhancing phase effects at lower electron densities. We studied the performance of the high magnification, low energy Talbot-Lau interferometer, for single image phase retrieval using Moiré fringe deflectometry. Our laboratory and simulation studies indicate that such a device is able to retrieve object electron densities from phase shift measurements. Using laboratory x-ray sources from 7 to 15 μm size we obtained accurate simultaneous measurements of refraction and attenuation for both sharp and mild electron density gradients.

First principles-based moiré model for incommensurate graphene on BN

NASA Astrophysics Data System (ADS)

Spataru, Catalin; Thurmer, Konrad

Various properties of supported graphene films depend strongly on the exact positions of carbon atoms with respect to the underlying substrate. While density functional theory (DFT) can predict atom position in many systems, it cannot be applied straightforwardly to systems that are incommensurate or have large unit cells, such as graphene on a BN surface. We address these limitations by developing a simple moiré model with parameters derived from DFT calculations for systems strained into commensurate structures with manageable unit cell sizes. Our moiré model, which takes into account the flexural rigidity of graphene and includes the influence of the substrate, is able to reproduce the DFT-relaxed carbon positions with an accuracy of <0.01 Å. We then apply this model to the unstrained C/BN system and predict how structure and energy vary with azimuthal orientation of the graphene sheet with respect to the BN substrate. Work supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Co., for the U.S. DOE under Contract DE-AC04-94AL85000.

Methodology for heritage conservation in Belgium based on multi-temporal interferometry

NASA Astrophysics Data System (ADS)

Bejarano-Urrego, L.; Verstrynge, E.; Shimoni, M.; Lopez, J.; Walstra, J.; Declercq, P.-Y.; Derauw, D.; Hayen, R.; Van Balen, K.

2017-09-01

Soil differential settlements that cause structural damage to heritage buildings are precipitating cultural and economic value losses. Adequate damage assessment as well as protection and preservation of the built patrimony are priorities at national and local levels, so they require advanced integration and analysis of environmental, architectural and historical parameters. The GEPATAR project (GEotechnical and Patrimonial Archives Toolbox for ARchitectural conservation in Belgium) aims to create an online interactive geo-information tool that allows the user to view and to be informed about the Belgian heritage buildings at risk due to differential soil settlements. Multi-temporal interferometry techniques (MTI) have been proven to be a powerful technique for analyzing earth surface deformation patterns through time series of Synthetic Aperture Radar (SAR) images. These techniques allow to measure ground movements over wide areas at high precision and relatively low cost. In this project, Persistent Scatterer Synthetic Aperture Radar Interferometry (PS-InSAR) and Multidimensional Small Baseline Subsets (MSBAS) are used to measure and monitor the temporal evolution of surface deformations across Belgium. This information is integrated with the Belgian heritage data by means of an interactive toolbox in a GIS environment in order to identify the level of risk. At country scale, the toolbox includes ground deformation hazard maps, geological information, location of patrimony buildings and land use; while at local scale, it includes settlement rates, photographic and historical surveys as well as architectural and geotechnical information. Some case studies are investigated by means of on-site monitoring techniques and stability analysis to evaluate the applied approaches. This paper presents a description of the methodology being implemented in the project together with the case study of the Saint Vincent's church which is located on a former colliery zone. For this building, damage is assessed by means of PSInSAR.

Process tool monitoring and matching using interferometry technique

NASA Astrophysics Data System (ADS)

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

2016-03-01

The semiconductor industry makes dramatic device technology changes over short time periods. As the semiconductor industry advances towards to the 10 nm device node, more precise management and control of processing tools has become a significant manufacturing challenge. Some processes require multiple tool sets and some tools have multiple chambers for mass production. Tool and chamber matching has become a critical consideration for meeting today's manufacturing requirements. Additionally, process tools and chamber conditions have to be monitored to ensure uniform process performance across the tool and chamber fleet. There are many parameters for managing and monitoring tools and chambers. Particle defect monitoring is a well-known and established example where defect inspection tools can directly detect particles on the wafer surface. However, leading edge processes are driving the need to also monitor invisible defects, i.e. stress, contamination, etc., because some device failures cannot be directly correlated with traditional visualized defect maps or other known sources. Some failure maps show the same signatures as stress or contamination maps, which implies correlation to device performance or yield. In this paper we present process tool monitoring and matching using an interferometry technique. There are many types of interferometry techniques used for various process monitoring applications. We use a Coherent Gradient Sensing (CGS) interferometer which is self-referencing and enables high throughput measurements. Using this technique, we can quickly measure the topography of an entire wafer surface and obtain stress and displacement data from the topography measurement. For improved tool and chamber matching and reduced device failure, wafer stress measurements can be implemented as a regular tool or chamber monitoring test for either unpatterned or patterned wafers as a good criteria for improved process stability.

PSP SAR interferometry monitoring of ground and structure deformations in the archeological site of Pompeii

NASA Astrophysics Data System (ADS)

Costantini, Mario; Francioni, Elena; Paglia, Luca; Minati, Federico; Margottini, Claudio; Spizzichino, Daniele; Trigila, Alessandro; Iadanza, Carla; De Nigris, Bruno

2016-04-01

The "Major Project Pompeii" (MPP) is a great collective commitment of different institututions and people to set about solving the serious problem of conservation of the largest archeological sites in the world. The ancient city of Pompeii with its 66 hectares, 44 of which are excaveted, is divided into 9 regiones (district), subdivided in 118 insulae (blocks) and almost 1500 domus (houses), and is Unesco site since 1996. The Italian Ministry for Heritage and Cultural Activities and Tourism (MiBACT) and Finmeccanica Group have sealed an agreement whereby the Finmeccanica Group will donate innovative technologies and services for monitoring and protecting the archaeological site of Pompeii. Moreover, the Italian Institute for Environment Protection and Research (ISPRA) - Geological Survey of Italy, was also involved to support the ground based analysis and interpretation of the measurements provided by the industrial team, in order to promote an interdisciplinary approach. In this work, we will focus on ground deformation measurements obtained by satellite SAR interferometry and on their interpretation. The satellite monitoring service is based on the processing of COSMO-SkyMed Himage data by the e-Geos proprietary Persistent Scatterer Pair (PSP) SAR interferometry technology. The PSP technique is a proven SAR interferometry method characterized by the fact of exploiting in the processing only the relative properties between close points (pairs) in order to overcome atmospheric artifacts (which are one of the main problems of SAR interferometry). Validations analyses showed that this technique applied to COSMO-SkyMed Himage data is able to retrieve very dense (except of course on vegetated or cultivated areas) millimetric deformation measurements with sub-metric localization. By means of the COSMO-SkyMed PSP SAR interferometry processing, a historical analysis of the ground and structure deformations occurred over the entire archaeological site of Pompeii in the period from 2010 to 2014 was initially performed. Moreover, the deformation monitoring is continuing with monthly updates of the PSP analysis with new COSMO-SkyMed acquisitions both in ascending and descending geometry. The first results of the preliminary analysis over the archaeological site of Pompeii did not show large areas affected by deformations. However, the COSMO-SkyMed PSP SAR interferometry analysis proved to be very efficient due to its capability of providing a large number of deformation measurements over the archaeological site and structures with relatively small impact and cost. Moreover, in areas affected by collapses in the recent past, deformations were detected. Recent instability processes, both for the unexcavated slopes and for the archaeological structures, have promoted this low-impact analysis, aimed at identifying deformation paths and to prevent sudden collapses. Finally, the results obtained from the satellite techniques, will be also used to implement and improve the ground based geotechnical monitoring and warning system recently installed in selected case studies. Cross analysis between interferometric results, meteorological data and historical data of the site (e.g. collapses, works, etc.) are in progress in order to define provisional model aiming at an early identification of areas subjected to potential instability.

Refractive Index Measurement of Fibers Through Fizeau Interferometry

DTIC Science & Technology

2013-08-01

15. SUBJECT TERMS composite, transparent, refractive index, refractometry , interferometer 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...transparent fibers has long presented a significant challenge. Abbe refractometry , the typical measurement technique for bulk materials and liquids

Space Radar Image of Saline Valley, California

NASA Image and Video Library

1999-04-15

This is a three-dimensional perspective view of Saline Valley, about 30 km 19 miles east of the town of Independence, California created by combining two spaceborne radar images using a technique known as interferometry.

PSP SAR interferometry monitoring of ground and structure deformations applied to archaeological sites

NASA Astrophysics Data System (ADS)

Costantini, Mario; Francioni, Elena; Trillo, Francesco; Minati, Federico; Margottini, Claudio; Spizzichino, Daniele; Trigila, Alessandro; Iadanza, Carla

2017-04-01

Archaeological sites and cultural heritage are considered as critical assets for the society, representing not only the history of region or a culture, but also contributing to create a common identity of people living in a certain region. In this view, it is becoming more and more urgent to preserve them from climate changes effect and in general from their degradation. These structures are usually just as precious as fragile: remote sensing technology can be useful to monitor these treasures. In this work, we will focus on ground deformation measurements obtained by satellite SAR interferometry and on the methodology adopted and implemented in order to use the results operatively for conservation policies in a Italian archaeological site. The analysis is based on the processing of COSMO-SkyMed Himage data by the e-GEOS proprietary Persistent Scatterer Pair (PSP) SAR interferometry technology. The PSP technique is a proven SAR interferometry technology characterized by the fact of exploiting in the processing only the relative properties between close points (pairs) in order to overcome atmospheric artefacts (which are one of the main problems of SAR interferometry). Validations analyses [Costantini et al. 2015] settled that this technique applied to COSMO-SkyMed Himage data is able to retrieve very dense (except of course on vegetated or cultivated areas) millimetric deformation measurements with sub-metric localization. Considering the limitations of all the interferometric techniques, in particular the fact that the measurement are along the line of sight (LOS) and the geometric distortions, in order to obtain the maximum information from interferometric analysis, both ascending and descending geometry have been used. The ascending analysis allows selecting measurements points over the top and, approximately, South-West part of the structures, while the descending one over the top and the South-East part of the structures. The interferometric techniques needs to use a stack of SAR images to separate the deformation phase contributions from other spurious components (atmospheric, orbital, etc.). Historical/reference analyses of the period 2011-2014 have been performed to obtain such deformations and to have a start point for the next updates. In fact, starting from the reference analyses the deformation monitoring has then continued with monthly updates of the PSP analysis with new COSMO-SkyMed acquisitions both in ascending and descending geometry. In addition to this traditional monitoring service, the satellite interferometry analysis has been realized over specific time frame that have been selected on the bases of some important events (damages to structures, collapses, works etc.) and the analysis have been correlated with additional site information as weather conditions, critical meteorological events, historical information of the site, etc. The objective is to find a nominal behaviour of the site in response to critical events and/or related to natural degradation of infrastructures in order to prevent damages and guide maintenance activities. The first results of this cross correlated analysis showed that some deformation phenomena are identifiable by SAR satellite interferometric analysis and it has also been possible to validate them on field through a direct survey.

Advanced interpretation of ground motion using Persistent Scatterer Interferometry technique: the Alto Guadalentín Basin (Spain) case of study

NASA Astrophysics Data System (ADS)

Bonì, Roberta; Herrera, Gerardo; Meisina, Claudia; Notti, Davide; Zucca, Francesco; Bejar, Marta; González, Pablo; Palano, Mimmo; Tomás, Roberto; Fernandez, José; Fernández-Merodo, José; Mulas, Joaquín; Aragón, Ramón; Mora, Oscar

2014-05-01

Subsidence related to fluid withdrawal has occurred in numerous regions of the world. The phenomena is an important hazard closely related to the development of urban areas. The analysis of the deformations requires an extensive and continuous spatial and temporal monitoring to prevent the negative effects of such risks on structures and infrastructures. Deformation measurements are fundamental in order to identify the affected area extension, to evaluate the temporal evolution of deformation velocities and to identify the main control mechanisms. Differential SAR interferometry represents an advanced remote sensing tool, which can map displacements at very high spatial resolution. The Persistent Scatterer Interferometry (PSI) technique is a class of SAR interferometry that uses point-wise radar targets (PS) on the ground whose phase is not interested by temporal and geometrical decorrelation. This technique generates starting from a set of images two main products: the displacement rate along line of sight (LOS) of single PS; and the LOS displacement time series of individual PS. In this work SAR data with different spatio-temporal resolution were used to study the displacements that occur from 1992 to 2012 in the Alto Guadalentin Basin (southern Spain), where is located the city of Lorca The area is affected by the highest rate of subsidence measured in Europe (>10 cm/yr-1) related to long-term exploitation of the aquifer (González et al. 2011). The objectives of the work were 1) to analyse land subsidence evolution over a 20-year period with PSI technique; 2) to compare the spatial and temporal resolution of SAR data acquired by different sensors, 3) to investigate the causes that could explain this land motion. The SAR data have been obtained with ERS-1/2 & ENVISAT (1992-2007), ALOS PALSAR (2007-2010) and COSMO-SkyMed (2011-2012) images, processed with the Stable Point Network (SPN) technique. The PSI data obtained from different satellite from 1992 to 2012 were compared with some predisposing and trigger factors as geological units, isobaths of Plio-Quaternary filling, soft soil thickness and piezometric level. The PSI data were compared with measurement obtained by two GPS station located near the Lorca city: the value of deformation detected by satellites and ground-based tools are well correlated. The results are the following: a) the subsidence processes are related to soft soil thickness distribution; b) land subsidence rates shows that the area interested by the higher value is the same over the monitored period, a deceleration rate of subsidence has been recorded during the period 2011- 2012; c) the deformation rates are not correlated with the piezometric level trend, a delay time between piezometric level variations and ground deformations is evident. References González, P. J. & Fernández, J.,(2011) Drought-driven transient aquifer compaction imaged using multitemporal satellite radar interferometry. Geology 39, pp. 551-554.

Research and Development in Very Long Baseline Interferometry (VLBI)

NASA Technical Reports Server (NTRS)

Himwich, William E.

2004-01-01

Contents include the following: 1.Observation coordination. 2. Data acquisition system control software. 3. Station support. 4. Correlation, data processing, and analysis. 5. Data distribution and archiving. 6. Technique improvement and research. 7. Computer support.

Phase retrieval in digital speckle pattern interferometry by use of a smoothed space-frequency distribution.

PubMed

Federico, Alejandro; Kaufmann, Guillermo H

2003-12-10

We evaluate the use of a smoothed space-frequency distribution (SSFD) to retrieve optical phase maps in digital speckle pattern interferometry (DSPI). The performance of this method is tested by use of computer-simulated DSPI fringes. Phase gradients are found along a pixel path from a single DSPI image, and the phase map is finally determined by integration. This technique does not need the application of a phase unwrapping algorithm or the introduction of carrier fringes in the interferometer. It is shown that a Wigner-Ville distribution with a smoothing Gaussian kernel gives more-accurate results than methods based on the continuous wavelet transform. We also discuss the influence of filtering on smoothing of the DSPI fringes and some additional limitations that emerge when this technique is applied. The performance of the SSFD method for processing experimental data is then illustrated.

Application of two-component phase Doppler interferometry to the measurement of particle size, mass flux, and velocities in two-phase flows

NASA Technical Reports Server (NTRS)

Mcdonell, V. G.; Samuelsen, G. S.

1989-01-01

Two-component phase Doppler interferometry is described, along with its application for the spatially-resolved measurements of particle size, velocity, and mass flux as well as continuous phase velocity. This technique measures single particle events at a point in the flow; droplet size is deduced from the spatial phase shift of the Doppler signal. Particle size influence and discrimination of continuous and discrete phases are among issues covered. Applications are presented for four cases: an example of the discrimination of two sizes of glass beads in a jet flow; a demonstration of the discrimination of phases in a spray field; an assessment of atomizer symmetry with respect to fuel distribution; and a characterization of a droplet field in a reacting spray. It is noted that the above technique is especially powerful in delineating droplet interactions in the swirling, complex flows typical of realistic systems.

Probing the solar corona with very long baseline interferometry.

PubMed

Soja, B; Heinkelmann, R; Schuh, H

2014-06-20

Understanding and monitoring the solar corona and solar wind is important for many applications like telecommunications or geomagnetic studies. Coronal electron density models have been derived by various techniques over the last 45 years, principally by analysing the effect of the corona on spacecraft tracking. Here we show that recent observational data from very long baseline interferometry (VLBI), a radio technique crucial for astrophysics and geodesy, could be used to develop electron density models of the Sun's corona. The VLBI results agree well with previous models from spacecraft measurements. They also show that the simple spherical electron density model is violated by regional density variations and that on average the electron density in active regions is about three times that of low-density regions. Unlike spacecraft tracking, a VLBI campaign would be possible on a regular basis and would provide highly resolved spatial-temporal samplings over a complete solar cycle.

Vibration-immune high-sensitivity profilometer built with the technique of composite interferometry.

PubMed

Lin, Yu-Kai; Chang, Chun-Wei; Hou, Max T; Hsu, I-Jen

2016-03-10

A prototype of a profilometer was built with the technique of composite interferometry for measurement of the distribution of both the amplitude and phase information of the surface of a material simultaneously. The composite interferometer was composed of a Michelson interferometer for measuring the surface profile of the sample and a Mach-Zehnder interferometer for measuring the phase deviation caused by the scanning component and environmental perturbations. A high-sensitivity surface profile can be obtained by use of the phase compensation mechanism through subtraction of the phases of the interferograms detected in the two interferometers. With the new design and improvement of robustness of the optical system, the measurement speed and accuracy were significantly improved. Furthermore, an additional optical delay component results in a higher sensitivity of the interference signal. This prototype of vibration-immune profilometer was examined to have a displacement sensitivity of 0.64 nm.

Seismic Interferometry at a Large, Dense Array: Capturing the Wavefield at the Source Physics Experiment

NASA Astrophysics Data System (ADS)

Matzel, E.; Mellors, R. J.; Magana-Zook, S. A.

2016-12-01

Seismic interferometry is based on the observation that the Earth's background wavefield includes coherent energy, which can be recovered by observing over long time periods, allowing the incoherent energy to cancel out. The cross correlation of the energy recorded at a pair of stations results in an estimate of the Green's Function (GF) and is equivalent to the record of a simple source located at one of the stations as recorded by the other. This allows high resolution imagery beneath dense seismic networks even in areas of low seismicity. The power of these inter-station techniques increases rapidly as the number of seismometers in a network increases. For large networks the number of correlations computed can run into the millions and this becomes a "big-data" problem where data-management dominates the efficiency of the computations. In this study, we use several methods of seismic interferometry to obtain highly detailed images at the site of the Source Physics Experiment (SPE). The objective of SPE is to obtain a physics-based understanding of how seismic waves are created at and scattered near the source. In 2015, a temporary deployment of 1,000 closely spaced geophones was added to the main network of instruments at the site. We focus on three interferometric techniques: Shot interferometry (SI) uses the SPE shots as rich sources of high frequency, high signal energy. Coda interferometry (CI) isolates the energy from the scattered wavefield of distant earthquakes. Ambient noise correlation (ANC) uses the energy of the ambient background field. In each case, the data recorded at one seismometer are correlated with the data recorded at another to obtain an estimate of the GF between the two. The large network of mixed geophone and broadband instruments at the SPE allows us to calculate over 500,000 GFs, which we use to characterize the site and measure the localized wavefield. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344

Incoherent averaging of phase singularities in speckle-shearing interferometry.

PubMed

Mantel, Klaus; Nercissian, Vanusch; Lindlein, Norbert

2014-08-01

Interferometric speckle techniques are plagued by the omnipresence of phase singularities, impairing the phase unwrapping process. To reduce the number of phase singularities by physical means, an incoherent averaging of multiple speckle fields may be applied. It turns out, however, that the results may strongly deviate from the expected √N behavior. Using speckle-shearing interferometry as an example, we investigate the mechanism behind the reduction of phase singularities, both by calculations and by computer simulations. Key to an understanding of the reduction mechanism during incoherent averaging is the representation of the physical averaging process in terms of certain vector fields associated with each speckle field.

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.

Model-based multi-fringe interferometry using Zernike polynomials

NASA Astrophysics Data System (ADS)

Gu, Wei; Song, Weihong; Wu, Gaofeng; Quan, Haiyang; Wu, Yongqian; Zhao, Wenchuan

2018-06-01

In this paper, a general phase retrieval method is proposed, which is based on one single interferogram with a small amount of fringes (either tilt or power). Zernike polynomials are used to characterize the phase to be measured; the phase distribution is reconstructed by a non-linear least squares method. Experiments show that the proposed method can obtain satisfactory results compared to the standard phase-shifting interferometry technique. Additionally, the retrace errors of proposed method can be neglected because of the few fringes; it does not need any auxiliary phase shifting facilities (low cost) and it is easy to implement without the process of phase unwrapping.

Phase retrieval in generalized optical interferometry systems.

PubMed

Farriss, Wesley E; Fienup, James R; Malhotra, Tanya; Vamivakas, A Nick

2018-02-05

Modal analysis of an optical field via generalized interferometry (GI) is a novel technique that treats said field as a linear superposition of transverse modes and recovers the amplitudes of modal weighting coefficients. We use phase retrieval by nonlinear optimization to recover the phase of these modal weighting coefficients. Information diversity increases the robustness of the algorithm by better constraining the solution. Additionally, multiple sets of random starting phase values assist the algorithm in overcoming local minima. The algorithm was able to recover nearly all coefficient phases for simulated fields consisting of up to 21 superpositioned Hermite Gaussian modes from simulated data and proved to be resilient to shot noise.

The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII)

NASA Technical Reports Server (NTRS)

Rinehart, Stephen A.

2010-01-01

Astronomical studies at infrared wavelengths have dramatically improved our understanding of the universe. The relatively low angular resolution of these missions, however, is insufficient to resolve the physical scale on which mid-to far-infrared emission arises. We will build the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII), an eight-meter Michelson interferometer to fly on a high-altitude balloon. BETTII's spectral-spatial capability, provided by an instrument using double-Fourier techniques, will address key questions about the nature of disks in young star clusters and active galactic nuclei and the envelopes of evolved stars. BETTII will also lay the technological groundwork for future space interferometers.

High throughput detection of antibody self-interaction by bio-layer interferometry.

PubMed

Sun, Tingwan; Reid, Felicia; Liu, Yuqi; Cao, Yuan; Estep, Patricia; Nauman, Claire; Xu, Yingda

2013-01-01

Self-interaction of an antibody may lead to aggregation, low solubility or high viscosity. Rapid identification of highly developable leads remains challenging, even though progress has been made with the introduction of techniques such as self-interaction chromatography (SIC) and cross-interaction chromatography (CIC). Here, we report a high throughput method to detect antibody clone self-interaction (CSI) using bio-layer interferometry (BLI) technology. Antibodies with strong self-interaction responses in the CSI-BLI assay also show delayed retention times in SIC and CIC. This method allows hundreds of candidates to be screened in a matter of hours with minimal material consumption.

BETTII: The Balloon Experimental Twin Telescope for Infrared Interferometry

NASA Technical Reports Server (NTRS)

Rinehart, Stephen

2011-01-01

Astronomical studies at infrared wavelengths have dramatically improved our understanding the universe. The relatively low angular resolution of these missions, however, is insufficient to resolve the physical scale on which mid-to far-infrared emission arises. We will build the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII),8oeight-meter Michelson interferometer to fly on a high-altitude balloon. BETTII's spectral-spatial capability, provided by an instrument using double-Fourier techniques, will address key questions about the nature of disks io young star clusters and active galactic nuclei and the envelopes of evolved stars. BETTII will also lay the technological groundwork for future space interferometers.

Photothermoplastic recording media and its application in the holographic method of determination of the refractive index of liquid objects.

PubMed

Davidenko, N A; Davidenko, I I; Pavlov, V A; Chuprina, N G; Kravchenko, V V; Kuranda, N N; Mokrinskaya, E V; Studzinsky, S L

2018-03-10

The photothermoplastic medium based on the films of photosensitive polymeric composites with semiconductor properties is developed for application in optical information recording and storage, in holographic interferometry, as well as for medical purposes. This medium was used in the modified holographic device for determination of changes of the refractive index of homogeneous and inhomogeneous liquid objects. The technique and holographic equipment were modified by employing the specially developed and produced transparent cuvette of special shape and the phase shifting interferometry method. Experimentally demonstrated precision of the measurements is not less than 10 -5 .

Fourier emission infrared microspectrophotometer for surface analysis. I - Application to lubrication problems

NASA Technical Reports Server (NTRS)

Lauer, J. L.; King, V. W.

1979-01-01

A far-infrared interferometer was converted into an emission microspectrophotometer for surface analysis. To cover the mid-infrared as well as the far-infrared the Mylar beamsplitter was made replaceable by a germanium-coated salt plate, and the Moire fringe counting system used to locate the moveable Michelson mirror was improved to read 0.5 micron of mirror displacement. Digital electronics and a dedicated minicomputer were installed for data collection and processing. The most critical element for the recording of weak emission spectra from small areas was, however, a reflecting microscope objective and phase-locked signal detection with simultaneous referencing to a blackbody source. An application of the technique to lubrication problems is shown.

Surface induced selective deposition of Dysprosium Polyoxometalate on HOPG surface studied by STM and STS

NASA Astrophysics Data System (ADS)

Costa Milan, David; Pinilla Cienfuegos, Elena; Cardona Serra, Salvador; Coronado Miralles, Eugenio; Untiedt Lecuona, Carlos

2013-03-01

Scanning Tunneling Microscope (STM) and scanning Tunnelling spectroscopy (STS) techniques have been used to study the Preyssler type Polyoxometalate K12[DyP5W30O110] molecules deposited on Highly Oriented Pyrolytic Graphite surface (HOPG). Chainlike arrangements of clusters containing two or three molecules, as well as different cluster sizes are observed. As many structural artifacts are present on the graphite surface, like Moiré patterns, that could look like the molecular deposits, we have studied their STS and size to ensure the presence of the POM molecules on the surface. This article shows the possibility of addressing POMs on a flat surface to obtain their electronic properties through STS.

Grating interferometry-based phase microtomography of atherosclerotic human arteries

NASA Astrophysics Data System (ADS)

Buscema, Marzia; Holme, Margaret N.; Deyhle, Hans; Schulz, Georg; Schmitz, Rüdiger; Thalmann, Peter; Hieber, Simone E.; Chicherova, Natalia; Cattin, Philippe C.; Beckmann, Felix; Herzen, Julia; Weitkamp, Timm; Saxer, Till; Müller, Bert

2014-09-01

Cardiovascular diseases are the number one cause of death and morbidity in the world. Understanding disease development in terms of lumen morphology and tissue composition of constricted arteries is essential to improve treatment and patient outcome. X-ray tomography provides non-destructive three-dimensional data with micrometer-resolution. However, a common problem is simultaneous visualization of soft and hard tissue-containing specimens, such as atherosclerotic human coronary arteries. Unlike absorption based techniques, where X-ray absorption strongly depends on atomic number and tissue density, phase contrast methods such as grating interferometry have significant advantages as the phase shift is only a linear function of the atomic number. We demonstrate that grating interferometry-based phase tomography is a powerful method to three-dimensionally visualize a variety of anatomical features in atherosclerotic human coronary arteries, including plaque, muscle, fat, and connective tissue. Three formalin-fixed, human coronary arteries were measured using advanced laboratory μCT. While this technique gives information about plaque morphology, it is impossible to extract the lumen morphology. Therefore, selected regions were measured using grating based phase tomography, sinograms were treated with a wavelet-Fourier filter to remove ring artifacts, and reconstructed data were processed to allow extraction of vessel lumen morphology. Phase tomography data in combination with conventional laboratory μCT data of the same specimen shows potential, through use of a joint histogram, to identify more tissue types than either technique alone. Such phase tomography data was also rigidly registered to subsequently decalcified arteries that were histologically sectioned, although the quality of registration was insufficient for joint histogram analysis.

Advances in imaging and quantification of electrical properties at the nanoscale using Scanning Microwave Impedance Microscopy (sMIM)

NASA Astrophysics Data System (ADS)

Friedman, Stuart; Yang, Yongliang; Amster, Oskar

2015-03-01

Scanning Microwave Impedance Microscopy (sMIM) is a mode for Atomic Force Microscopy (AFM) enabling imaging of unique contrast mechanisms and measurement of local permittivity and conductivity at the 10's of nm length scale. Recent results will be presented illustrating high-resolution electrical features such as sub 15 nm Moire' patterns in Graphene, carbon nanotubes of various electrical states and ferro-electrics. In addition to imaging, the technique is suited to a variety of metrology applications where specific physical properties are determined quantitatively. We will present research activities on quantitative measurements using multiple techniques to determine dielectric constant (permittivity) and conductivity (e.g. dopant concentration) for a range of materials. Examples include bulk dielectrics, low-k dielectric thin films, capacitance standards and doped semiconductors. Funded in part by DOE SBIR DE-SC0009586.

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

Dynamic Deformation of ETNA Volcano Observed by GPS and SAR Interferometry

NASA Technical Reports Server (NTRS)

Lundgren, P.; Rosen, P.; Webb, F.; Tesauro, M.; Lanari, R.; Sansosi, E.; Puglisi, G.; Bonforte, A.; Coltelli, M.

1999-01-01

Synthetic aperture radar (SAR) interferometry and GPS have shown that during the quiescent period from 1993-1995 Mt. Etna volcano, Italy, inflated. Since the initiation of eruptive activity since late 1995 the deformation has been more contentious. We will explore the detailed deformation during the period from 1995-1996 spanning the late stages of inflation and the beginning of eruptive activity. We use SAR interferometry and GPS data to measure the volcano deformation. We invert the observed deformation for both simple point source. le crack elastic sources or if warranted for a spheroidal pressure So In particular, we will examine the evolution of the inflation and the transition to a lesser deflation observed at the end of 1995. We use ERS-1/2 SAR data from both ascending and descending passes to allow for dense temporal 'sampling of the deformation and to allow us to critically assess atmospheric noise. Preliminary results from interferometry suggest that the inflation rate accelerated prior to resumption of activity in 1995, while GPS data suggest a more steady inflation with some fluctuation following the start of activity. This study will compare and contrast the interferometric SAR and GPS results and will address the strengths and weaknesses of each technique towards volcano deformation studies.

Assessing tear film on soft contact lenses with lateral shearing interferometry.

PubMed

Szczesna, Dorota H

2011-11-01

Evaluating precorneal tear film is one of important clinical measurements for assessing health of anterior eye. Contact lens wear is known to influence the quality of tear film. The aim was to evaluate the applicability of lateral shearing interferometry technique in the noninvasive assessment of the effects of contact lens replacement modality and its water content on tear film stability. Sixteen regular soft contact lens wearers took place in the study. Lateral shearing interferometry measurements, in suppressed blinking conditions, were taken in the mornings and afternoons, after a minimum of 5 hours of lens wear for the daily lenses, and after 2 weeks and 1 month for the fortnightly and monthly lens replacement modalities, respectively. Significant differences (paired bootstrap-based Behrens-Fisher test, P < 0.05) in the tear film surface quality were found between all considered pairs of replacement modalities except for the daily and fortnightly lenses measured in the afternoon of the first day of wear. Significant worsening (paired bootstrap-based Behrens-Fisher test, P < 0.001) of tear film quality was found for the low water content materials. Lateral shearing interferometry is a powerful method for the noninvasive assessment of tear film surface quality on soft contact lenses that may find, in future, its use in the clinical assessment of anterior eye's health.

Residual stresses investigations in composite samples by speckle interferometry and specimen repositioning

NASA Astrophysics Data System (ADS)

Baldi, Alfonso; Jacquot, Pierre

2003-05-01

Graphite-epoxy laminates are subjected to the "incremental hole-drilling" technique in order to investigate the residual stresses acting within each layer of the composite samples. In-plane speckle interferometry is used to measure the displacement field created by each drilling increment around the hole. Our approach features two particularities (1) we rely on the precise repositioning of the samples in the optical set-up after each new boring step, performed by means of a high precision, numerically controlled milling machine in the workshop; (2) for each increment, we acquire three displacement fields, along the length, the width of the samples, and at 45°, using a single symmetrical double beam illumination and a rotary stage holding the specimens. The experimental protocol is described in detail and the experimental results are presented, including a comparison with strain gages. Speckle interferometry appears as a suitable method to respond to the increasing demand for residual stress determination in composite samples.

SAR Interferometry as a Tool for Monitoring Coastal Changes in the Nile River Delta of Egypt

NASA Technical Reports Server (NTRS)

Aly, Mohamed H.; Klein, Andrew G.; Giardino, John R.

2005-01-01

The Nile River Delta is experiencing rapid rates of coastal change. The rate of both coastal retreat and accretion in the Eastern Nile Delta requires regular, accurate detection and measurement. Current techniques used to monitor coastal changes in the delta are point measurements and, thus, they provide a spatially limited view of the ongoing coastal changes. SAR interferometry can provide measurements of subtle coastal change at a significantly improved spatial resolution and over large areas (100 sq km). Using data provided by the ERS-1&2 satellites, monitoring can be accomplished as frequently as every 35 days when needed. Radar interferometry is employed in this study to detect segments of erosion and accretion during the 1993-2000 period. The average rates of erosion and accretion in the Eastern Nile Delta are measured to be -11.64 m/yr and +5.12 m/yr, respectively. The results of this interferometric study can be used effectively for coastal zone management and integrated sustainable development for the Nile River Delta.

On-line surface inspection using cylindrical lens-based spectral domain low-coherence interferometry.

PubMed

Tang, Dawei; Gao, Feng; Jiang, X

2014-08-20

We present a spectral domain low-coherence interferometry (SD-LCI) method that is effective for applications in on-line surface inspection because it can obtain a surface profile in a single shot. It has an advantage over existing spectral interferometry techniques by using cylindrical lenses as the objective lenses in a Michelson interferometric configuration to enable the measurement of long profiles. Combined with a modern high-speed CCD camera, general-purpose graphics processing unit, and multicore processors computing technology, fast measurement can be achieved. By translating the tested sample during the measurement procedure, real-time surface inspection was implemented, which is proved by the large-scale 3D surface measurement in this paper. ZEMAX software is used to simulate the SD-LCI system and analyze the alignment errors. Two step height surfaces were measured, and the captured interferograms were analyzed using a fast Fourier transform algorithm. Both 2D profile results and 3D surface maps closely align with the calibrated specifications given by the manufacturer.

Interfaces detection after corneal refractive surgery by low coherence optical interferometry

PubMed Central

Verrier, I.; Veillas, C.; Lépine, T.; Nguyen, F.; Thuret, G.; Gain, P.

2010-01-01

The detection of refractive corneal surgery by LASIK, during the storage of corneas in Eye Banks will become a challenge when the numerous operated patients will arrive at the age of cornea donation. The subtle changes of corneal structure and refraction are highly suspected to negatively influence clinical results in recipients of such corneas. In order to detect LASIK cornea interfaces we developed a low coherence interferometry technique using a broadband continuum source. Real time signal recording, without moving any optical elements and without need of a Fourier Transform operation, combined with good measurement resolution is the main asset of this interferometer. The associated numerical processing is based on a method initially used in astronomy and offers an optimal correlation signal without the necessity to image the whole cornea that is time consuming. The detection of corneal interfaces - both outer and inner surface and the buried interface corresponding to the surgical wound – is then achieved directly by the innovative combination of interferometry and this original numerical process. PMID:21258562

The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII): Spatially Resolved Spectroscopy in the Far-Infrared

NASA Technical Reports Server (NTRS)

Rinehart, Stephen

2009-01-01

Astronomical studies at infrared wavelengths have dramatically improved our understanding of the universe, and observations with Spitzer, the upcoming Herschel mission, and SOFIA will continue to provide exciting new discoveries. The relatively low angular resolution of these missions, however, is insufficient to resolve the physical scale on which mid-to far-infrared emission arises, resulting in source and structure ambiguities that limit our ability to answer key science questions. Interferometry enables high angular resolution at these wavelengths - a powerful tool for scientific discovery. We will build the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII), an eight-meter baseline Michelson stellar interferometer to fly on a high-altitude balloon. BETTII's spectral-spatial capability, provided by an instrument using double-Fourier techniques, will address key questions about the nature of disks in young star clusters and active galactic nuclei and the envelopes of evolved stars. BETTII will also lay the technological groundwork for future space interferometers and for suborbital programs optimized for studying extrasolar planets.

Remote monitoring of the earthquake cycle using satellite radar interferometry.

PubMed

Wright, Tim J

2002-12-15

The earthquake cycle is poorly understood. Earthquakes continue to occur on previously unrecognized faults. Earthquake prediction seems impossible. These remain the facts despite nearly 100 years of intensive study since the earthquake cycle was first conceptualized. Using data acquired from satellites in orbit 800 km above the Earth, a new technique, radar interferometry (InSAR), has the potential to solve these problems. For the first time, detailed maps of the warping of the Earth's surface during the earthquake cycle can be obtained with a spatial resolution of a few tens of metres and a precision of a few millimetres. InSAR does not need equipment on the ground or expensive field campaigns, so it can gather crucial data on earthquakes and the seismic cycle from some of the remotest areas of the planet. In this article, I review some of the remarkable observations of the earthquake cycle already made using radar interferometry and speculate on breakthroughs that are tantalizingly close.

The Dynamic Atmospheres of Carbon Rich Giants: Constraining Models Via Interferometry

NASA Astrophysics Data System (ADS)

Rau, Gioia; Hron, Josef; Paladini, Claudia; Aringer, Bernard; Eriksson, Kjell; Marigo, Paola

2016-07-01

Dynamic models for the atmospheres of C-rich Asymptotic Giant Branch stars are quite advanced and have been overall successful in reproducing spectroscopic and photometric observations. Interferometry provides independent information and is thus an important technique to study the atmospheric stratification and to further constrain the dynamic models. We observed a sample of six C-rich AGBs with the mid infrared interferometer VLTI/MIDI. These observations, combined with photometric and spectroscopic data from the literature, are compared with synthetic observables derived from dynamic model atmospheres (DMA, Eriksson et al. 2014). The SEDs can be reasonably well modelled and the interferometry supports the extended and multi-component structure of the atmospheres, but some differences remain. We discuss the possible reasons for these differences and we compare the stellar parameters derived from this comparison with stellar evolution models. Finally, we point out the high potential of MATISSE, the second generation VLTI instrument allowing interferometric imaging in the L, M, and N bands, for further progress in this field.

Hyperspectral Thermal Infrared Remote Sensing of the Land Surface and Target Identification using Airborne Interferometry

DTIC Science & Technology

2009-10-01

variational data assimilation technique are profiles of temperature, water vapour and ozone , surface temperature and spectrally varying emissivity. HOW TO...that are insensitive to the land surface because of the complexity of the land surface emissivity. We have utilised the techniques described here for...state as well as surface properties. Furthermore with by utilising a variational assimilation technique and a state of the art Numerical Weather

Extension of electronic speckle correlation interferometry to large deformations

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Sciammarella, Federico M.

1998-07-01

The process of fringe formation under simultaneous illumination in two orthogonal directions is analyzed. Procedures to extend the applicability of this technique to large deformation and high density of fringes are introduced. The proposed techniques are applied to a number of technical problems. Good agreement is obtained when the experimental results are compared with results obtained by other methods.

Regional distribution of forest height and biomass from multisensor data fusion

Treesearch

Yifan Yu; Sassan Saatch; Linda S. Heath; Elizabeth LaPoint; Ranga Myneni; Yuri Knyazikhin

2010-01-01

Elevation data acquired from radar interferometry at C-band from SRTM are used in data fusion techniques to estimate regional scale forest height and aboveground live biomass (AGLB) over the state of Maine. Two fusion techniques have been developed to perform post-processing and parameter estimations from four data sets: 1 arc sec National Elevation Data (NED), SRTM...

Ocular dispersion

NASA Astrophysics Data System (ADS)

Hammer, Daniel X.; Noojin, Gary D.; Thomas, Robert J.; Stolarski, David J.; Rockwell, Benjamin A.; Welch, Ashley J.

1999-06-01

Spectrally resolved white-light interferometry (SRWLI) was used to measure the wavelength dependence of refractive index (i.e., dispersion) for various ocular components. The accuracy of the technique was assessed by measurement of fused silica and water, the refractive indices of which have been measured at several different wavelengths. The dispersion of bovine and rabbit aqueous and vitreous humor was measured from 400 to 1100 nm. Also, the dispersion was measured from 400 to 700 nm for aqueous and vitreous humor extracted from goat and rhesus monkey eyes. For the humors, the dispersion did not deviate significantly from water. In an additional experiment, the dispersion of aqueous and vitreous humor that had aged up to a month was compared to freshly harvested material. No difference was found between the fresh and aged media. An unsuccessful attempt was also made to use the technique for dispersion measurement of bovine cornea and lens. Future refinement may allow measurement of the dispersion of cornea and lens across the entire visible and near-infrared wavelength band. The principles of white- light interferometry including image analysis, measurement accuracy, and limitations of the technique, are discussed. In addition, alternate techniques and previous measurements of ocular dispersion are reviewed.

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.

Simultaneous topography and tomography of latent fingerprints using full-field swept-source optical coherence tomography

NASA Astrophysics Data System (ADS)

Dubey, Satish Kumar; Singh Mehta, Dalip; Anand, Arun; Shakher, Chandra

2008-01-01

We demonstrate simultaneous topography and tomography of latent fingerprints using full-field swept-source optical coherence tomography (OCT). The swept-source OCT system comprises a superluminescent diode (SLD) as broad-band light source, an acousto-optic tunable filter (AOTF) as frequency tuning device, and a compact, nearly common-path interferometer. Both the amplitude and the phase map of the interference fringe signal are reconstructed. Optical sectioning of the latent fingerprint sample is obtained by selective Fourier filtering and the topography is retrieved from the phase map. Interferometry, selective filtering, low coherence and hence better resolution are some of the advantages of the proposed system over the conventional fingerprint detection techniques. The present technique is non-invasive in nature and does not require any physical or chemical processing. Therefore, the quality of the sample does not alter and hence the same fingerprint can be used for other types of forensic test. Exploitation of low-coherence interferometry for fingerprint detection itself provides an edge over other existing techniques as fingerprints can even be lifted from low-reflecting surfaces. The proposed system is very economical and compact.

Vibration Analysis Of Automotive Structures Using Holographic Interferometry

NASA Astrophysics Data System (ADS)

Brown, G. M.; Wales, R. R.

1983-10-01

Since 1979, Ford Motor Company has been developing holographic interferometry to supplement more conventional test methods to measure vehicle component vibrations. An Apollo PHK-1 Double Pulse Holographic Laser System was employed to visualize a variety of complex vibration modes, primarily on current production and prototype powertrain components. Design improvements to reduce powertrain response to problem excitations have been deter-mined through pulsed laser holography, and have, in several cases, been put into production in Ford vehicles. Whole-field definition of vibration related deflections provide continuity of information missed by accelerometer/modal analysis techniaues. Certain opera-tional problems, common among pulsed ruby holographic lasers, have reauired ongoing hardware and electronics improvements to minimize system downtime. Real-time, time-averaged and stroboscopic C. W. laser holographic techniques are being developed at Ford to complement the double pulse capabilities and provide rapid identification of modal frequencies and nodal lines for analysis of powertrain structures. Methods for mounting and exciting powertrains to minimize rigid body motions are discussed. Work at Ford will continue toward development of C. W. holographic techniques to provide refined test methodology dedicated to noise and vibration diagnostics with particular emphasis on semi-automated methods for quantifying displacement and relative phase using high resolution digitized video and computers. Continued use of refined pulsed and CW laser holographic interferometry for the analysis of complex structure vibrations seems assured.

Monitoring the tidal response of a sea levee with ambient seismic noise

NASA Astrophysics Data System (ADS)

Planès, Thomas; Rittgers, Justin B.; Mooney, Michael A.; Kanning, Wim; Draganov, Deyan

2017-03-01

Internal erosion, a major cause of failure of earthen dams and levees, is often difficult to detect at early stages using traditional visual inspection. The passive seismic-interferometry technique could enable the early detection of internal changes taking place within these structures. We test this technique on a portion of the sea levee of Colijnsplaat, Netherlands, which presents signs of concentrated seepage in the form of sandboils. Applying seismic interferometry to ambient noise collected over a 12-hour period, we retrieve surface waves propagating along the levee. We identify the contribution of two dominant ambient seismic noise sources: the traffic on the Zeeland bridge and a nearby wind turbine. Here, the sea-wave action does not constitute a suitable noise source for seismic interferometry. Using the retrieved surface waves, we compute time-lapse variations of the surface-wave group velocities during the 12-hour tidal cycle for different frequency bands, i.e., for different depth ranges. The estimated group-velocity variations correlate with variations in on-site pore-water pressure measurements that respond to tidal loading. We present lateral profiles of these group-velocity variations along a 180-meter section of the levee, at four different depth ranges (0m-40m). On these profiles, we observe some spatially localized relative group-velocity variations of up to 5% that might be related to concentrated seepage.

On safe ground? Analysis of European urban geohazards using satellite radar interferometry

NASA Astrophysics Data System (ADS)

Capes, Renalt; Teeuw, Richard

2017-06-01

Urban geological hazards involving ground instability can be costly, dangerous, and affect many people, yet there is little information about the extent or distribution of geohazards within Europe's urban areas. A reason for this is the impracticality of measuring ground instability associated with the many geohazard processes that are often hidden beneath buildings and are imperceptible to conventional geological survey detection techniques. Satellite radar interferometry, or InSAR, offers a remote sensing technique to map mm-scale ground deformation over wide areas given an archive of suitable multi-temporal data. The EC FP7 Space project named PanGeo (2011-2014), used InSAR to map areas of unstable ground in 52 of Europe's cities, representing ∼15% of the EU population. In partnership with Europe's national geological surveys, the PanGeo project developed a standardised geohazard-mapping methodology and recorded 1286 instances of 19 types of geohazard covering 18,000 km2. Presented here is an analysis of the results of the PanGeo-project output data, which provides insights into the distribution of European urban geohazards, their frequency and probability of occurrence. Merging PanGeo data with Eurostat's GeoStat data provides a systematic estimate of population exposures. Satellite radar interferometry is shown to be as a valuable tool for the systematic detection and mapping of urban geohazard phenomena.

Nonnegative Matrix Factorization for Efficient Hyperspectral Image Projection

NASA Technical Reports Server (NTRS)

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

2015-01-01

Hyperspectral imaging for remote sensing has prompted development of hyperspectral image projectors that can be used to characterize hyperspectral imaging cameras and techniques in the lab. One such emerging astronomical hyperspectral imaging technique is wide-field double-Fourier interferometry. NASA's current, state-of-the-art, Wide-field Imaging Interferometry Testbed (WIIT) uses a Calibrated Hyperspectral Image Projector (CHIP) to generate test scenes and provide a more complete understanding of wide-field double-Fourier interferometry. Given enough time, the CHIP is capable of projecting scenes with astronomically realistic spatial and spectral complexity. However, this would require a very lengthy data collection process. For accurate but time-efficient projection of complicated hyperspectral images with the CHIP, the field must be decomposed both spectrally and spatially in a way that provides a favorable trade-off between accurately projecting the hyperspectral image and the time required for data collection. We apply nonnegative matrix factorization (NMF) to decompose hyperspectral astronomical datacubes into eigenspectra and eigenimages that allow time-efficient projection with the CHIP. Included is a brief analysis of NMF parameters that affect accuracy, including the number of eigenspectra and eigenimages used to approximate the hyperspectral image to be projected. For the chosen field, the normalized mean squared synthesis error is under 0.01 with just 8 eigenspectra. NMF of hyperspectral astronomical fields better utilizes the CHIP's capabilities, providing time-efficient and accurate representations of astronomical scenes to be imaged with the WIIT.

Electronic dispersion from long-range atomic ordering and periodic potentials in two overlapping graphene sheets

NASA Astrophysics Data System (ADS)

Ohta, Taisuke; Robinson, Jeremy; Feibelman, Peter; Beechem, Thomas; Diaconescu, Bogdan; Bostwick, Aaron; Rotenberg, Eli; Kellogg, Gary

2013-03-01

A worldwide effort is underway to learn how to build devices that take advantage of the remarkable electronic properties of graphene and other two-dimensional crystals. An outstanding question is how stacking two or a few such crystals affects their joint electronic behavior. Our talk concerns ``twisted bilayer graphene (TBG),'' that is, two graphene layers azimuthally misoriented. Applying angle-resolved photoemission spectroscopy and density functional theory, we have found van Hove singularities (vHs) and associated mini-gaps in the TBG electronic spectrum, which represent unambiguous proof that the layers interact. Of particular interest is that the measured and calculated electronic dispersion manifests the periodicity of the moiré superlattice formed by the twist. Thus, there are vHs not just where the Dirac cones of the two layers overlap, but also at the boundaries of the moiré superlattice Brillouin zone. Moirés, ubiquitous in hybrid solids based on two-dimensional crystals, accordingly present themselves as tools for manipulating the electronic behavior. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Validation of a Hartmann-Moiré wavefront sensor with large dynamic range.

PubMed

Wei, Xin; Van Heugten, Tony; Thibos, Larry

2009-08-03

Our goal was to validate the accuracy, repeatability, sensitivity, and dynamic range of a Hartmann-Moiré (HM) wavefront sensor (PixelOptics, Inc.) designed for ophthalmic applications. Testing apparatus injected a 4 mm diameter monochromatic (532 nm) beam of light into the wavefront sensor for measurement. Controlled amounts of defocus and astigmatism were introduced into the beam with calibrated spherical (-20D to + 18D) and cylindrical (-8D to + 8D) lenses. Repeatability was assessed with three repeated measurements within a 2-minute period. Correlation coefficients between mean wavefront measurements (n = 3) and expected wavefront vergence for both sphere and cylinder lenses were >0.999. For spherical lenses, the sensor was accurate to within 0.1D over the range from -20D to + 18D. For cylindrical lenses, the sensor was accurate to within 0.1D over the range from -8D to + 8D. The primary limitation to demonstrating an even larger dynamic range was the increasingly critical requirements for optical alignment. Sensitivity to small changes of vergence was constant over the instrument's full dynamic range. Repeatability of measurements for fixed condition was within 0.01D. The Hartmann-Moiré wavefront sensor measures defocus and astigmatism accurately and repeatedly with good sensitivity over a large dynamic range required for ophthalmic applications.

Basic research for the geodynamics program

NASA Technical Reports Server (NTRS)

Mueller, I. I.

1985-01-01

The current technical objectives for the geodynamics program consist of (1) optimal utilization of laser and Very Long Baseline Interferometry (VLBI) observations for reference frames for geodynamics; (2) utilization of range difference observations in geodynamics; and (3) estimation techniques in crustal deformation analysis.

Experimental 3-D residual stress measurement in rails with thermal annealing

DOT National Transportation Integrated Search

1999-07-01

This report describes a novel method to determine residual stresses in railroad rails. The method uses thermal annealing to relieve the internal stresses in rail slices while advanced techniques (Miore and Twyman/Green interferometry) are applied to ...

Attosecond electronic recollision as field detector

NASA Astrophysics Data System (ADS)

Carpeggiani, P. A.; Reduzzi, M.; Comby, A.; Ahmadi, H.; Kühn, S.; Frassetto, F.; Poletto, L.; Hoff, D.; Ullrich, J.; Schröter, C. D.; Moshammer, R.; Paulus, G. G.; Sansone, G.

2018-05-01

We demonstrate the complete reconstruction of the electric field of visible–infrared pulses with energy as low as a few tens of nanojoules. The technique allows for the reconstruction of the instantaneous electric field vector direction and magnitude, thus giving access to the characterization of pulses with an arbitrary time-dependent polarization state. The technique combines extreme ultraviolet interferometry with the generation of isolated attosecond pulses.

X-ray phase scanning setup for non-destructive testing using Talbot-Lau interferometer

NASA Astrophysics Data System (ADS)

Bachche, S.; Nonoguchi, M.; Kato, K.; Kageyama, M.; Koike, T.; Kuribayashi, M.; Momose, A.

2016-09-01

X-ray grating interferometry has a great potential for X-ray phase imaging over conventional X-ray absorption imaging which does not provide significant contrast for weakly absorbing objects and soft biological tissues. X-ray Talbot and Talbot-Lau interferometers which are composed of transmission gratings and measure the differential X-ray phase shifts have gained popularity because they operate with polychromatic beams. In X-ray radiography, especially for nondestructive testing in industrial applications, the feasibility of continuous sample scanning is not yet completely revealed. A scanning setup is frequently advantageous when compared to a direct 2D static image acquisition in terms of field of view, exposure time, illuminating radiation, etc. This paper demonstrates an efficient scanning setup for grating-based Xray phase imaging using laboratory-based X-ray source. An apparatus consisting of an X-ray source that emits X-rays vertically, optical gratings and a photon-counting detector was used with which continuously moving objects across the field of view as that of conveyor belt system can be imaged. The imaging performance of phase scanner was tested by scanning a long continuous moving sample at a speed of 5 mm/s and absorption, differential-phase and visibility images were generated by processing non-uniform moire movie with our specially designed phase measurement algorithm. A brief discussion on the feasibility of phase scanner with scanning setup approach including X-ray phase imaging performance is reported. The successful results suggest a breakthrough for scanning objects those are moving continuously on conveyor belt system non-destructively using the scheme of X-ray phase imaging.