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Full-Text Articles in Physics

Different Topological Quantum States In Ternary Zintl Compounds: Bacax (X = Si, Ge, Sn And Pb), Lin-Lin Wang, Adam Kaminski, Paul C. Canfield, Duane D. Johnson Jan 2018

Different Topological Quantum States In Ternary Zintl Compounds: Bacax (X = Si, Ge, Sn And Pb), Lin-Lin Wang, Adam Kaminski, Paul C. Canfield, Duane D. Johnson

Ames Laboratory Accepted Manuscripts

Topological quantum states require stringent combination of crystal symmetry and spin–orbit coupling (SOC) strength. Here, we report that the ternary Zintl compound series BaCaX (X = Si, Ge, Sn and Pb, Group IV) in the same crystal structure having eight valence electrons per formula unit can host two different topological quantum phases, controlled by atomic size and SOC strength. BaCaSi is a nodal-line semimetal (NLSM) with band inversion protected by mirror symmetry and hosts a strong topological insulator (TI) state when SOC is turned on, thus, a NLSM-TI phase. Moving to larger atomic sizes and heavier atoms, BaCaGe and BaCaSn ...


Oleds On Flexible Substrates, Chamika M. Hippola Jan 2018

Oleds On Flexible Substrates, Chamika M. Hippola

Creative Components

In some applications flexible plastic substrates are advantageous over glass substrates for organic light emitting diode (OLED) fabrication due to properties such as higher refractive index, ease ofnano-patterning for enhanced extraction of light generated in the OLED, and promise in wearable electronics and biochemical sensing. Defects, impurities, and in particular sharp edges that may be formed in patterned plastic substrates such as polycarbonate (PC) can lead to catastrophic shorts when biased due to very high local electric fields. This work evaluated various PC substrates and their treatment with the goal of identifying the best substrates for patterning for enhancing OLED ...


Optical Absorption Properties Of Ge2–44 And P-Doped Ge Nanoparticles, Wei Qin, Wen-Cai Lu, Li-Zhen Zhao, Kai-Ming Ho, Cai-Zhuang Wang Dec 2017

Optical Absorption Properties Of Ge2–44 And P-Doped Ge Nanoparticles, Wei Qin, Wen-Cai Lu, Li-Zhen Zhao, Kai-Ming Ho, Cai-Zhuang Wang

Ames Laboratory Accepted Manuscripts

The optical absorption properties of non-crystalline and crystalline Ge nanoparticles with the sizes from ∼2.5 to 15 Å have been studied at the B3LYP/6-31G level using time-dependent density functional theory. Hydrogen passivation and phosphorus doping on some selected Ge nanoparticles were also calculated. With the increase of cluster size, the optical absorption spectra of the non-crystalline Ge nanoparticles change from many peaks to a continuous broad band and at the same time exhibit a systematic red-shift. Doping phosphorus also causes the absorption spectra to shift toward the lower energy region for both non-crystalline and crystalline Ge nanoparticles. The ...


Near Infrared And Optical Beam Steering And Frequency Splitting In Air Holes-In-Silicon Inverse Photonic Crystals, Anna Tasolamprou, Thomas Koschny, Maria Kafesaki, Costas Soukoulis Sep 2017

Near Infrared And Optical Beam Steering And Frequency Splitting In Air Holes-In-Silicon Inverse Photonic Crystals, Anna Tasolamprou, Thomas Koschny, Maria Kafesaki, Costas Soukoulis

Ames Laboratory Accepted Manuscripts

We present the design of a dielectric inverse photonic crystal structure that couples line-defect waveguide propagating modes into highly directional beams of controllable directionality. The structure utilizes a triangular lattice made of air holes drilled in an infinitely thick Si slab, and it is designed for operation in the near-infrared and optical regime. The structure operation is based on the excitation and manipulation of dark dielectric surface states, in particular on the tailoring of the dark states’ coupling to outgoing radiation. This coupling is achieved with the use of properly designed external corrugations. The structure adapts and matches modes that ...


Red-Emitting Manganese-Doped Aluminum Nitride Phosphor, Nerine J. Cherepy, Stephen A. Payne, Nicholas M. Harvey, Daniel Åberg, Zachary M. Seeley, Kiel S. Holliday, Ich C. Tran, Fei Zhou, H. Paul Martinez, Jessica M. Demeyer, Alexander D. Drobshoff, Alok M. Srivastava, Samuel J. Camardello, Holly A. Comanzo, Deborah L. Schlagel, Thomas A. Lograsso Apr 2016

Red-Emitting Manganese-Doped Aluminum Nitride Phosphor, Nerine J. Cherepy, Stephen A. Payne, Nicholas M. Harvey, Daniel Åberg, Zachary M. Seeley, Kiel S. Holliday, Ich C. Tran, Fei Zhou, H. Paul Martinez, Jessica M. Demeyer, Alexander D. Drobshoff, Alok M. Srivastava, Samuel J. Camardello, Holly A. Comanzo, Deborah L. Schlagel, Thomas A. Lograsso

Materials Science and Engineering Publications

We report high efficiency luminescence with a manganese-doped aluminum nitride red-emitting phosphor under 254 nm excitation, as well as its excellent lumen maintenance in fluorescent lamp conditions, making it a candidate replacement for the widely deployed europium-doped yttria red phosphor. Solid-state reaction of aluminum nitride powders with manganese metal at 1900 °C, 10 atm N2 in a reducing environment results in nitrogen deficiency, as revealed diffuse reflectance spectra. When these powders are subsequently annealed in flowing nitrogen at 1650 °C, higher nitrogen content is recovered, resulting in white powders. Silicon was added to samples as an oxygen getter to improve ...


Unoccupied Electronic Structure Of Ni2mnga Ferromagnetic Shape Memory Alloy, M. Maniraj, S. W. D′Souza, Abhishek Rai, Deborah L. Schlagel, Thomas A. Lograsso, Aparna Chakrabarti, S. R. Barman Nov 2015

Unoccupied Electronic Structure Of Ni2mnga Ferromagnetic Shape Memory Alloy, M. Maniraj, S. W. D′Souza, Abhishek Rai, Deborah L. Schlagel, Thomas A. Lograsso, Aparna Chakrabarti, S. R. Barman

Ames Laboratory Publications

Momentum resolved inverse photoemission spectroscopy measurements show that the dispersion of the unoccupied bands of Ni2MnGa is significant in the austenite phase. In the martensite phase, it is markedly reduced, which is possibly related to the structural transition to an incommensurate modulated state in the martensite phase. Based on the first principle calculations of the electronic structure of Ni–Mn–Ga, we show that the modification of the spectral shape with surface composition is related to change in the hybridization between the Mn 3d and Ni 3d-like states that dominate the unoccupied conduction band.


Soft Lithography Microlens Fabrication And Array For Enhanced Light Extraction From Organic Light Emitting Diodes (Oleds), Wai Y. Leung, Joong-Mok Park, Zhengqing Gan, Kristen P. Constant, Joseph Shinar, Ruth Shinar, Kai-Ming Ho Jun 2014

Soft Lithography Microlens Fabrication And Array For Enhanced Light Extraction From Organic Light Emitting Diodes (Oleds), Wai Y. Leung, Joong-Mok Park, Zhengqing Gan, Kristen P. Constant, Joseph Shinar, Ruth Shinar, Kai-Ming Ho

Iowa State University Patents

Provided are microlens arrays for use on the substrate of OLEDs to extract more light that is trapped in waveguided modes inside the devices and methods of manufacturing same. Light extraction with microlens arrays is not limited to the light emitting area, but is also efficient in extracting light from the whole microlens patterned area where waveguiding occurs. Large microlens array, compared to the size of the light emitting area, extract more light and result in over 100% enhancement. Such a microlens array is not limited to (O)LEDs of specific emission, configuration, pixel size, or pixel shape. It is ...


Manufacturing Method Of Photonic Crystal, In Sung Park, Tae Ho Lee, Jin Ho Ahn, Rana Biswas, Kristen P. Constant, Kai-Ming Ho, Jae-Hwang Lee Jan 2013

Manufacturing Method Of Photonic Crystal, In Sung Park, Tae Ho Lee, Jin Ho Ahn, Rana Biswas, Kristen P. Constant, Kai-Ming Ho, Jae-Hwang Lee

Iowa State University Patents

A manufacturing method of a photonic crystal is provided. In the method, a high-refractive-index material is conformally deposited on an exposed portion of a periodic template composed of a low-refractive-index material by an atomic layer deposition process so that a difference in refractive indices or dielectric constants between the template and adjacent air becomes greater, which makes it possible to form a three-dimensional photonic crystal having a superior photonic bandgap. Herein, the three-dimensional structure may be prepared by a layer-by-layer method.


Metal-Nanowall Grating Transparent Electrodes: Achieving High Optical Transmittance At High Incident Angles With Minimal Diffraction, Ping Kuang, Joong Mok Park, Geyuan Liu, Zhuo Ye, Wai Y. Leung, Sumit Chaudhary, David W. Lynch, Kai-Ming Ho, Kristen P. Constant Jan 2013

Metal-Nanowall Grating Transparent Electrodes: Achieving High Optical Transmittance At High Incident Angles With Minimal Diffraction, Ping Kuang, Joong Mok Park, Geyuan Liu, Zhuo Ye, Wai Y. Leung, Sumit Chaudhary, David W. Lynch, Kai-Ming Ho, Kristen P. Constant

Materials Science and Engineering Publications

A novel architecture has been employed to fabricate transparent electrodes with high conductivity and high optical transmittance at high incident angles. Soft lithography is used to fabricate polymer grating patterns onto which thin metallic films are deposited. Etching removes excess metal leaving tall walls of metal. Polymer encapsulation of the structure both protects the metal and minimizes diffraction. Transmission is dependent upon the height of the walls and encapsulation and varies from 60% to 80% for structures with heights of 1400 nm to 300 nm. In encapsulated structures, very little distortion is visible (either parallel to or perpendicular to standing ...


Photonic Crystal: Energy-Related Applications, Zhuo Ye, Joong Mok Park, Kristen P. Constant, Tae Guen Kim, Kai-Ming Ho Jun 2012

Photonic Crystal: Energy-Related Applications, Zhuo Ye, Joong Mok Park, Kristen P. Constant, Tae Guen Kim, Kai-Ming Ho

Materials Science and Engineering Publications

We review recent work on photonic-crystal fabrication using soft-lithography techniques. We consider applications of the resulting structures in energy-related areas such as lighting and solar-energy harvesting. In general, our aim is to introduce the reader to the concepts of photonic crystals, describe their history, development, and fabrication techniques and discuss a selection of energy-related applications.


Soft Holographic Interference Lithography Microlens For Enhanced Organic Light Emitting Diode Light Extraction, Joong Mok Park, Zhengqing Gan, Wai Y. Leung, Rui Liu, Zhuo Ye, Kristen P. Constant, Joseph Shinar, Ruth Shinar, Kai-Ming Ho Jul 2011

Soft Holographic Interference Lithography Microlens For Enhanced Organic Light Emitting Diode Light Extraction, Joong Mok Park, Zhengqing Gan, Wai Y. Leung, Rui Liu, Zhuo Ye, Kristen P. Constant, Joseph Shinar, Ruth Shinar, Kai-Ming Ho

Materials Science and Engineering Publications

Very uniform 2 μm-pitch square microlens arrays (μLAs), embossed on the blank glass side of an indium-tin-oxide (ITO)-coated 1.1 mm-thick glass, are used to enhance light extraction from organic light-emitting diodes (OLEDs) by ~100%, significantly higher than enhancements reported previously. The array design and size relative to the OLED pixel size appear to be responsible for this enhancement. The arrays are fabricated by very economical soft lithography imprinting of a polydimethylsiloxane (PDMS) mold (itself obtained from a Ni master stamp that is generated from holographic interference lithography of a photoresist) on a UV-curable polyurethane drop placed on the ...


Fabrication Of Submicron Metallic Grids With Interference And Phase-Mask Holography, Joong Mok Park, Tae Geun Kim, Kristen P. Constant, Kai-Ming Ho Jan 2011

Fabrication Of Submicron Metallic Grids With Interference And Phase-Mask Holography, Joong Mok Park, Tae Geun Kim, Kristen P. Constant, Kai-Ming Ho

Materials Science and Engineering Publications

Complex, submicron Cu metallic mesh nanostructures are made by electrochemical deposition using polymer templates made from photoresist. The polymer templates are fabricated with photoresist using two-beam interference holography and phase mask holography with three diffracted beams. Freestanding metallic mesh structures are made in two separate electrodepositions with perpendicular photoresist grating templates. Cu mesh square nanostructures having large (52.6%) open areas are also made by single electrodeposition with a photoresist template made with a phase mask. These structures have potential as electrodes in photonic devices.


Semicrystalline Woodpile Photonic Crystals Without Complicated Alignment Via Soft Lithography, Jae-Hwang Lee, Ping Kuang, Wai Y. Leung, Yong-Sung Kim, Joong Mok Park, Henry Kang, Kristen P. Constant, Kai-Ming Ho Jan 2010

Semicrystalline Woodpile Photonic Crystals Without Complicated Alignment Via Soft Lithography, Jae-Hwang Lee, Ping Kuang, Wai Y. Leung, Yong-Sung Kim, Joong Mok Park, Henry Kang, Kristen P. Constant, Kai-Ming Ho

Materials Science and Engineering Publications

We report the fabrication and characterization of woodpile photonic crystals with up to 12 layers through titania nanoparticle infiltration of a polymer template made by soft lithography. Because the complicated alignment in the conventional layer-by-layer fabrication associated with diamondlike symmetry is replaced by a simple 90° alignment, the fabricatedphotonic crystal has semicrystalline phase. However, the crystal performs similarly to a perfectly aligned crystal for the light propagation integrated from the surface normal to 30° at the main photonic band gap.


Polarized Thermal Radiation By Layer-By-Layer Metallic Emitters With Sub-Wavelength Grating, Jae-Hwang Lee, Wai Y. Leung, Tae Guen Kim, Kristen P. Constant, Kai-Ming Ho Jun 2008

Polarized Thermal Radiation By Layer-By-Layer Metallic Emitters With Sub-Wavelength Grating, Jae-Hwang Lee, Wai Y. Leung, Tae Guen Kim, Kristen P. Constant, Kai-Ming Ho

Materials Science and Engineering Publications

Metallic thermal emitters consisting of two layers of differently structured nickel gratings on a homogeneous nickel layer are fabricated by soft lithography and studied for polarized thermal radiation. A thermal emitter in combination with a sub-wavelength grating shows a high extinction ratio, with a maximum value close to 5, in a wide mid-infrared range from 3.2 to 7.8 µm, as well as high emissivity up to 0.65 at a wavelength of 3.7µm. All measurements show good agreement with theoretical predictions. Numerical simulations reveal that a high electric field exists within the localized air space surrounded by ...


Three-Dimensional Metallic Photonic Crystals Fabricated By Soft Lithography For Midinfrared Applications, Jae-Hwang Lee, Chang-Hwan Kim, Yong-Sung Kim, Kai-Ming Ho, Kristen P. Constant, Cha-Hwan Oh Jan 2006

Three-Dimensional Metallic Photonic Crystals Fabricated By Soft Lithography For Midinfrared Applications, Jae-Hwang Lee, Chang-Hwan Kim, Yong-Sung Kim, Kai-Ming Ho, Kristen P. Constant, Cha-Hwan Oh

Materials Science and Engineering Publications

We present an efficient method of fabricating freestanding three-dimensional metallic photonic crystals using soft lithography. Low cost and ease of fabrication are achieved through gold sputter deposition on a freestanding woodpile polymer template. We compare experimental results to theoretical calculations for tetragonal and face-centered-tetragonal structures as a function of the number of layers. The photonic crystals behave like full metallic structures with a photonic band edge at a wavelength of 3.5μm. The rejection rates of the structures are about 10dB/layer.


Photonic Bandgaps Of Conformally Coated Structures, Rana Biswas, Jinho Ahn, Taoho Lee, Jae-Hwang Lee, Yong-Sung Kim, Chang-Hwan Kim, Wai Y. Leung, Cha-Hwan Oh, Kristen P. Constant, Kai-Ming Ho Dec 2005

Photonic Bandgaps Of Conformally Coated Structures, Rana Biswas, Jinho Ahn, Taoho Lee, Jae-Hwang Lee, Yong-Sung Kim, Chang-Hwan Kim, Wai Y. Leung, Cha-Hwan Oh, Kristen P. Constant, Kai-Ming Ho

Materials Science and Engineering Publications

Polymeric molds of the layer-by-layer photonic crystal can be economically synthesized with a microtransfer molding technique. The refractive indices of these molds are low, preventing formation of a photonic bandgap. We find that such molds can be conformally coated with higher-index material. Photonic band calculations find structures in which conformally coated layer-by-layer molds have complete bandgaps for both titania and silicon coatings. Large stop bands exist in the 001 stacking direction. Feasibility of experimental conformal coating of the molds has been demonstrated with a titania-coated polyurethane mold, which shows optical features in agreement with simulations of reflection and transmission.


Diffracted Moiré Fringes As Analysis And Alignment Tools For Multilayer Fabrication In Soft Lithography, Jae-Hwang Lee, Chang-Hwan Kim, Yong-Sung Kim, Kai-Ming Ho, Kristen P. Constant, Wai Y. Leung, Cha-Hwan Oh Jan 2005

Diffracted Moiré Fringes As Analysis And Alignment Tools For Multilayer Fabrication In Soft Lithography, Jae-Hwang Lee, Chang-Hwan Kim, Yong-Sung Kim, Kai-Ming Ho, Kristen P. Constant, Wai Y. Leung, Cha-Hwan Oh

Materials Science and Engineering Publications

We studied the first-order diffractedmoiré fringes of transparent multilayered structures comprised of irregularly deformed periodic patterns. By a comparison study of the diffractedmoiré fringe pattern and detailed microscopy of the structure, we show that the diffractedmoiré fringe can be used as a nondestructive tool to analyze the alignment of multilayered structures. We demonstrate the alignment method for the case of layer-by-layer microstructures using soft lithography. The alignment method yields high contrast of fringes even when the materials being aligned have very weak contrasts. The imaging method of diffractedmoiré fringes is a versatile visual tool for the microfabrication of transparent deformable ...


Fabrication Of Photonic Band Gap Crystal Using Microtransfer Molded Templates, Wai Y. Leung, Henry Kang, Kristen P. Constant, D. Cann, Chang-Hwan Kim, Rana Biswas, M. M. Sigalas, Kai-Ming Ho Jan 2003

Fabrication Of Photonic Band Gap Crystal Using Microtransfer Molded Templates, Wai Y. Leung, Henry Kang, Kristen P. Constant, D. Cann, Chang-Hwan Kim, Rana Biswas, M. M. Sigalas, Kai-Ming Ho

Materials Science and Engineering Publications

We have proposed and demonstrated an economical technique to fabricate a three-dimensional layer-by-layer photonic band gapstructure in the infrared wavelengths. An organic polymer template structure, an inverse layer-by-layer photonic crystalstructure, is assembled using the microtransfer molding technique. This template is infiltrated with sol-gel or nanoparticle titanium oxide slurry, then later removed by heat treatment at a temperature range of 550–800 °C. This method can be extended to fabricatephotonic crystals operating at optical and ultraviolet frequencies.


Structural Characterization Of Thin Film Photonic Crystals, G. Subramania, Rana Biswas, Kristen P. Constant, M. M. Sigalas, Kai-Ming Ho May 2001

Structural Characterization Of Thin Film Photonic Crystals, G. Subramania, Rana Biswas, Kristen P. Constant, M. M. Sigalas, Kai-Ming Ho

Materials Science and Engineering Publications

We quantitatively analyze the structure of thin film inverse-opal photonic crystals composed of ordered arrays of air pores in a background of titania. Ordering of the sphere template and introduction of the titania background were performed simultaneously in the thin film photonic crystals. Nondestructive optical measurements of backfilling with high refractive index liquids, angle-resolved reflectivity, and optical spectroscopy were combined with band-structure calculations. The analysis reveals a thin film photonic crystal structure with a very high filling fraction (92–94 %) of air and a substantial compression along the c axis (∼22–25%).


Optical Photonic Crystals Fabricated From Colloidal Systems, G. Subramania, Kristen P. Constant, Rana Biswas, M. M. Sigalas, Kai-Ming Ho Jun 1999

Optical Photonic Crystals Fabricated From Colloidal Systems, G. Subramania, Kristen P. Constant, Rana Biswas, M. M. Sigalas, Kai-Ming Ho

Materials Science and Engineering Publications

Photonic crystals of close-packed arrays of air spheres in a dielectric background of titania have been fabricated with a ceramic technique. Unlike previous methods, ordering of the spheres and the formation of the titania network are performed simultaneously. The photonic crystals exhibit a reflectance peak and a uniform color at the position of the first stop band. The wavelength of the reflectance peak scales very well with the sphere size.


Application Of Diffracto Sight Ot The Nondestructive Inspection Of Aircraft Structures, Jerzy Komorowski, Ronald W. Gould, David L. Simpson, Omer Hageniers Jan 1993

Application Of Diffracto Sight Ot The Nondestructive Inspection Of Aircraft Structures, Jerzy Komorowski, Ronald W. Gould, David L. Simpson, Omer Hageniers

Review of Progress in Quantitative Nondestructive Evaluation

The D Sight optical set up was first assembled nearly ten years ago at Diffracto Ltd. It has received several patents, the first of which was in the United States [1]. Since the mid 1980’s, D Sight has been successfully applied to surface quality inspections, particularly in the automotive and plastics industries. Recently, Komorowski et al. [2–5] have shown several potential applications of D Sight in the field of nondestructive inspection of aircraft structures. The technique has been shown to be particularly effective in locating nonvisible impact damage on large surfaces of aircraft structures built from composite materials ...


High-Speed Time-Resolved Holography For Imaging Transient Events, Michael Ehrlich, James W. Wagner Jan 1993

High-Speed Time-Resolved Holography For Imaging Transient Events, Michael Ehrlich, James W. Wagner

Review of Progress in Quantitative Nondestructive Evaluation

A time-resolved holographic system was developed to study detonation dynamics in dispersed solid particulate explosives. This required a system capable of recording a rapid sequence of exposures during the approximate 1/µs lifetime of the detonation event.


General Automated Flaw Detection Scheme For Nde X-Ray Images, Karl Ulmer, John P. Basart Jan 1993

General Automated Flaw Detection Scheme For Nde X-Ray Images, Karl Ulmer, John P. Basart

Review of Progress in Quantitative Nondestructive Evaluation

This paper presents an approach to automated flaw detection (AFD) in an arbitrary X-ray image. The intensities in the digitized radiographic image are modeled as piecewise-smooth surface functions corrupted by noise and flaws. It has been observed that radiographs generated for NDE purposes containing flaws also have a combination of three unwanted features; background trends, geometrical structures, and noise. These features inhibit the performance of automated flaw detection algorithms. The proposed general processing scheme reduces the unwanted features in such a way that candidate flaws within the image can be identified. The proposed scheme is robust and is applicable to ...


Electronic Holography And Shearography Nde For Inspection Of Modern Materials And Structures, J. Clarady, M. Summers Jan 1993

Electronic Holography And Shearography Nde For Inspection Of Modern Materials And Structures, J. Clarady, M. Summers

Review of Progress in Quantitative Nondestructive Evaluation

Coherent optical techniques such as holography, shearography, and ESPI have been available for inspection applications for years. However, they are still not well known or widely used. In fact, they have sometimes been described as “a solution looking for a problem” and like so many new technologies, they may have been somewhat oversold. These optical NDE methods do, however, offer some impressive advantages over more conventional inspection techniques for the right applications. It is the intent of this paper to provide some basic information on how two of these optical methods, holography and shearography, work discuss capabilities and limitations of ...


Beam Profile Reflectometry: A New Technique For Thin Film Measurements, J. Fanton, J. Opsal, D. L. Willenborg, S. M. Kelso, Allan Rosencwaig Jan 1993

Beam Profile Reflectometry: A New Technique For Thin Film Measurements, J. Fanton, J. Opsal, D. L. Willenborg, S. M. Kelso, Allan Rosencwaig

Review of Progress in Quantitative Nondestructive Evaluation

In the manufacture of semiconductor devices, it is of critical importance to know the thickness and material properties of various dielectric and semiconducting thin films. Although there are many techniques for measuring these films, the most commonly used are reflection spectrophotometry [1,2] and ellipsometry [3]. In the former method, the normal- incidence reflectivity is measured as a function of wavelength. The shape of the reflectivity spectrum is then analyzed using the Fresnel equations to determine the thickness of the film. In some cases, the refractive index can also be determined provided that the dispersion of the optical constants are ...


Electronic Shearography: Current Capabilities, Potential Limitations, And Future Possibilities For Industrial Nondestructive Inspection, John Deaton Jr., Robert S. Rogowski Jan 1993

Electronic Shearography: Current Capabilities, Potential Limitations, And Future Possibilities For Industrial Nondestructive Inspection, John Deaton Jr., Robert S. Rogowski

Review of Progress in Quantitative Nondestructive Evaluation

Image-shearing speckle pattern interferometry, more commonly referred to as ‘shearography’, is a full-field, laser-based interferometric technique first developed for applications in experimental mechanics [1,2]. Shearography is sensitive to derivatives of the out-of-plane surface displacement of a body under load, as opposed to other full-field methods such as holographic interferometry and conventional speckle pattern interferometry, which typically contour the surface displacement directly [3]. The early shearography experiments used high-resolution photographic film to record images of the laser speckle patterns. In contrast to traditional film-based techniques, electronic shearography uses an electronic camera for image recording [4]. This technology, commercially available for ...


Quantitative Analysis Of A Class Of Subsurface Cracks Using Shearography And Finite Element Modeling, Leland Melvin, Brooks A. Childers, James P. Fulton Jan 1993

Quantitative Analysis Of A Class Of Subsurface Cracks Using Shearography And Finite Element Modeling, Leland Melvin, Brooks A. Childers, James P. Fulton

Review of Progress in Quantitative Nondestructive Evaluation

The application of a full field non-contacting measurement system for nondestructively evaluating (NDE) subsurface flaws in structures has been conducted using Electronic Shearography. Shearography has primarily been used as a qualitative tool for locating areas of stress concentration caused by anomalies in materials[1–4]. NASA has been applying optical techniques such as these to NDE inspection of aircraft lap joint integrity, composite material defects, and pressure vessel quality assurance. This paper examines a special class of defects manufactured in thin metal panels and serves as a testbed for interpreting the displacement gradients produced on a simple well-characterized sample with ...


Laser Shearographic Testing Of Foam Insulation On Cryogenic Fuel Tanks, Douglas Burleigh, James E. Engel, David R. Kuhns Jan 1993

Laser Shearographic Testing Of Foam Insulation On Cryogenic Fuel Tanks, Douglas Burleigh, James E. Engel, David R. Kuhns

Review of Progress in Quantitative Nondestructive Evaluation

The Centaur is a high-energy rocket used as a second stage to the Atlas launch vehicle. The Centaur is cryogenically fueled, using liquid hydrogen and liquid oxygen, and requires insulation to prevent fuel boiloff prior to launch. The original insulation system used on Centaur is a set of fiberglass honeycomb panels, which are jettisoned after launch. These panels are still used on the Atlas I version of Atlas/Centaur.


Shearography With Syncrhonized Pressure Stressing, Tom Chatters, Bruno Pouet, Sridhar Krishnaswamy Jan 1993

Shearography With Syncrhonized Pressure Stressing, Tom Chatters, Bruno Pouet, Sridhar Krishnaswamy

Review of Progress in Quantitative Nondestructive Evaluation

Non-destructive evaluation (NDE) techniques of optical video-based speckle interferometry are gaining importance as inspection tools, particularly by the aerospace industry [1,2]. An optical technique such as shearography is attractive to the NDE community largely because of its non-contacting nature, full-field measurement and fast inspection results. However, in order for this optical interferometric method to become widely used as an NDE tool, this technique must be made to be robust enough to operate in noisy environments typically found in industry settings. In this paper, we address these issues for the case of detection of disbonds using shearography in conjunction with ...


Practical Estimates Of The Errors Associated With The Governing Shearography Equation, John Fulton, M. Namkung, L. D. Melvin Jan 1993

Practical Estimates Of The Errors Associated With The Governing Shearography Equation, John Fulton, M. Namkung, L. D. Melvin

Review of Progress in Quantitative Nondestructive Evaluation

In a series of papers Hung[1–3] pioneered the development of shearography, an optical NDE technique that detects gradients of surface displacements. Its utility for qualitative flaw characterization has been demonstrated, and while there is a need for using shearography in NDE for quantitative analysis, a large amount of the research[2–7] has concentrated on the qualitative evaluation of structures and materials. The purpose of this paper is to begin building upon a foundation for the newly emerging quantitative shearography[8].