1. Articles in category: NDE/NDT

    1-24 of 200 1 2 3 4 5 6 7 8 9 »
    1. High resolution Fourier domain optical coherence tomography in the 2 μm wavelength range using a broadband supercontinuum source

      High resolution Fourier domain optical coherence tomography in the 2 μm wavelength range using a broadband supercontinuum source

      A 220 nm bandwidth supercontinuum source in the two-micron wavelength range has been developed for use in a Fourier domain optical coherence tomography (FDOCT) system. This long wavelength source serves to enhance probing depth in highly scattering material with low water content. We present results confirming improved penetration depth in high opacity paint samples while achieving the high axial resolution needed to resolve individual paint layers. This is the first FDOCT developed in the 2 μm wavelength regime that allows fast, efficient capturing of 3D image cubes at a high axial resolution of 13 μm in air (or 9 μm ...

      Read Full Article
    2. High resolution Fourier domain optical coherence tomography in the 2 um wavelength range using a broadband supercontinuum source

      High resolution Fourier domain optical coherence tomography in the 2 um wavelength range using a broadband supercontinuum source

      A 220 nm bandwidth supercontinuum source in the two-micron wavelength range has been developed for use in a Fourier domain optical coherence tomography (FDOCT) system. This long wavelength source serves to enhance probing depth in highly scattering material with low water content. We present results confirming improved penetration depth in high opacity paint samples while achieving the high axial resolution needed to resolve individual paint layers. This is the first FDOCT developed in the 2 μm wavelength regime that allows fast, efficient capturing of 3D image cubes at a high axial resolution of 13 μm in air (or 9 μm ...

      Read Full Article
    3. Hydrogel-coated feed spacers in two-phase flow cleaning in spiral wound membrane elements: A novel platform for eco-friendly biofouling mitigation

      Hydrogel-coated feed spacers in two-phase flow cleaning in spiral wound membrane elements: A novel platform for eco-friendly biofouling mitigation

      Biofouling is still a major challenge in the application of nanofiltration and reverse osmosis membranes. Here we present a platform approach for environmentally friendly biofouling control using a combination of a hydrogel-coated feed spacer and two-phase flow cleaning. Neutral (polyHEMA-co-PEG 10 MA), cationic (polyDMAEMA) and anionic (polySPMA) hydrogels have been successfully grafted onto polypropylene (PP) feed spacers via plasma-mediated UV-polymerization. These coatings maintained their chemical stability after 7 days incubation in neutral (pH 7), acidic (pH 5) and basic (pH 9) environments. Anti-biofouling properties of these coatings were evaluated by Escherichia coli attachment assay and nanofiltration experiments at a TMP ...

      Read Full Article
    4. Quantitative assessment of touch-screen panel by nondestructive inspection with three-dimensional real-time display optical coherence tomography

      Quantitative assessment of touch-screen panel by nondestructive inspection with three-dimensional real-time display optical coherence tomography

      We investigated the use of optical coherence tomography (OCT) to measure several materials immersed in optical adhesives. The effects of variations in the concentration, physical characteristics, and thickness of the materials were studied, and these parameters were found to significantly affect the OCT measurement. The materials were selected for their distinct spectral properties in the infrared region. To ensure reliability, we acquired images using a scanning electron microscope after performing the semiconductor production process. We verified the feasibility of the application of OCT for defect inspection and product verification of touch-screen panels.

      Read Full Article
    5. Optical coherence tomography as film thickness measurement technique

      Optical coherence tomography as film thickness measurement technique

      Optical coherence tomography (OCT) is a powerful optical method, noninvasive and noncontact diagnostic method. Although it is usually used for medical examinations, particularly in ocular exploration; it can also be used in optical metrology as measure technique. In this work, we use OCT to measure thicknesses of films. In OCT, depth profiles are constructed by measuring the time delay of back reflected light by interferometry measurements. Frequency in k-space is proportional to optical path difference. Then the reflectivity profile is obtained by a Fourier transformation, and the difference between two successive peaks of the resulting spectrum gives the film thickness ...

      Read Full Article
    6. Feature Of The Week 01/04/2015: Zhejiang University Investigates Ultrawide-Field SD-OCT for NDE of Large Glass Surfaces

      Feature Of The Week 01/04/2015: Zhejiang University Investigates Ultrawide-Field SD-OCT for NDE of Large Glass Surfaces

      Due to its merits of nondestruction and high-resolution, the use of OCT in material industry is increased recently. Besides profilometry of metal, monitoring of printed electronics, nondestructive inspection of glass is another important application. Material defects such as bubbles, impurities, and distortion affect the quality of glass. To realize quality control of glass, a technique for nondestructive inspection of glass is required. Given the large amount of glass productions, a large field-of-view (FOV) is necessary for the system to achieve high-speed inspection. However, as the required FOV becomes large, conventional OCT system always encounters the problem of image distortion because ...

      Read Full Article
    7. Polarization-sensitive optical coherence tomography for ceramic materials inspection

      Polarization-sensitive optical coherence tomography for ceramic materials inspection

      Ceramics production is looking for a fast, reliable and non-destructive method that can be implemented on site for defect detection and analysis. In this paper we present polarization-sensitive optical coherence tomography (PS-OCT) as a method for defect inspection. Proposed extensions to standard OCT provide additional information for complete characterization of tested object. We compare OCT and microscope imaging that can easily detect enamel layer defects. The object under test is a sample ceramic plate with several defects occurring in production process. Results of OCT imaging show those defects are only in enamel layer without any effect on potsherd layer.

      Read Full Article
    8. Optical Coherence Tomography for Material Characterization (Thesis)

      Optical Coherence Tomography for Material Characterization (Thesis)

      Optical coherence tomography (OCT) is a non-invasive, contactless and high resolution imaging method, which allows the reconstruction of two or three dimensional depth-resolved images in turbid media. In the past 20 years, OCT has been extensively developed in the field of biomedical diagnostics, while OCT in the non-destructive testing (NDT) field is lagging far behind. The aim of this thesis is to use OCT as a novel NDT technique for material structure characterization and damage detection. Besides an overview of the OCT fundamentals and developments, the thesis is mainly driven by three tasks: instrument design, signal processing, and applications. An ...

      Read Full Article
    9. Gravity-driven membrane filtration as pretreatment for seawater reverse osmosis: Linking biofouling layer morphology with flux stabilization

      Gravity-driven membrane filtration as pretreatment for seawater reverse osmosis: Linking biofouling layer morphology with flux stabilization

      In this study gravity-driven membrane (GDM) ultrafiltration is investigated for the pretreatment of seawater before reverse osmosis (RO). The impacts of temperature (21 ± 1 and 29 ± 1 °C) and hydrostatic pressure (40 and 100 mbar) on dynamic flux development and biofouling layer structure were studied. The data suggested pore constriction fouling was predominant at the early stage of filtration, during which the hydrostatic pressure and temperature had negligible effects on permeate flux. With extended filtration time, cake layer fouling played a major role, during which higher hydrostatic pressure and temperature improved permeate flux. The permeate flux stabilized in a range ...

      Read Full Article
    10. Ultrawide-field parallel spectral domain optical coherence tomography for nondestructive inspection of glass

      Ultrawide-field parallel spectral domain optical coherence tomography for nondestructive inspection of glass

      Aiming at the requirements of real-time inspection in material industry, an ultrawide-field parallel SD-OCT system capable of visualizing cross-sectional image of internal structures by a single shot of a 2-D CMOS camera is developed. To achieve ultrawide-field parallel detection, one meniscus lens with negative dioptric is introduced as an additional relay lens and imaging optics including sample arm, relay lenses and spectrometer are optimized as a whole for desirable imaging quality. The developed system has an ultrawide-field of 35 mm and an axial range of 8 mm in air. The maximum on-axis sensitivity and the axial resolution are experimentally determined ...

      Read Full Article
    11. DETECTION OF SUBSURFACE DAMAGE IN OPTICAL TRANSPARENT MATERIALSS USING SHORT COHERENCE TOMOGRAPHY

      DETECTION OF SUBSURFACE DAMAGE IN OPTICAL TRANSPARENT MATERIALSS USING SHORT COHERENCE TOMOGRAPHY

      This paper describes the use of short coherence interferometry for the detection of subsurface damage (SSD) in optical transparent materials. The method is based on an interferometer using a light source with a short coherence length. A time domain (TD) and a frequency domain (FD) approach are explained. The OCT method allows a nondestructive measurement of the SSD compared to the state of the art SSD metrology, where the sample is destroyed. Compared to previous results [Ser10] a frequency domain (FD) setup is build up which allows SSD measurements under production environment conditions. The results of the FD set are ...

      Read Full Article
    12. Optical coherence tomography in the 2um wavelength regime for paint and other high opacity materials

      Optical coherence tomography in the 2um wavelength regime for paint and other high opacity materials

      An optical coherence tomography system using a compact fiber source emitting amplified spontaneous emission at central wavelength of 1960 nm with bandwidth of 40 nm is developed to enhance the probing depth in a highly scattering material with low water content. Examples of application to paint are used to demonstrate significantly improved penetration depth in high opacity materials in the 2-μm wavelength regime.

      Read Full Article
    13. A Novel Approach to Characterizing the Growth of a Fouling Layer during Membrane Filtration via Optical Coherence Tomography

      A Novel Approach to Characterizing the Growth of a Fouling Layer during Membrane Filtration via Optical Coherence Tomography

      Fouling control is one of the critical issues in membrane filtration and plays a very important role in water/wastewater treatment. Better understanding of the underlying fouling mechanisms entails novel characterization techniques that can realize a real-time non-invasive observation and provide high resolution images recording the formation of a fouling layer . This work presents a characterization method based on optical coherence tomography (OCT), which is able to detect the internal structures and motions by analyzing the interference signals. An OCT system was incorporated with a lab-scale membrane filtration system, and the growth of the fouling layer was observed by using ...

      Read Full Article
    14. Machining Head For A Laser Machining Device Comprising A PATH-LENGTH Modulator In The Reference Arm; Method For Laser Machining Of A Workpiece, Comprising Corresponding Steps

      Machining Head For A Laser Machining Device Comprising A PATH-LENGTH Modulator In The Reference Arm; Method For Laser Machining Of A Workpiece, Comprising Corresponding Steps

      The invention relates to a machining head for a laser machining device, which is equipped for machining a workpiece (24) using laser radiation (30). The laser machining head comprises an adjustable focusing optical unit (34), which focuses the laser radiation (30) in a focal spot (22). The distance between the focal spot (22) and a machining head can be modified by modifying the focal length of the focusing optical unit (34). A scanning apparatus (44) deflects the laser radiation (30) in different directions. An optical coherence tomography device (48) measures a distance between the treatment head and the workpiece (24 ...

      Read Full Article
    15. Accurate and automated image segmentation of 3D optical coherence tomography data suffering from low signal-to-noise levels

      Accurate and automated image segmentation of 3D optical coherence tomography data suffering from low signal-to-noise levels

      Optical coherence tomography (OCT) has proven to be a useful tool for investigating internal structures in ceramic tapes, and the technique is expected to be important for roll-to-roll manufacturing. However, because of high scattering in ceramic materials, noise and speckles deteriorate the image quality, which makes automated quantitative measurements of internal interfaces difficult. To overcome this difficulty we present in this paper an innovative image analysis approach based on volumetric OCT data. The engine in the analysis is a 3D image processing and analysis algorithm. It is dedicated to boundary segmentation and dimensional measurement in volumetric OCT images, and offers ...

      Read Full Article
    16. Air etalon facilitated simultaneous measurement of group refractive index and thickness using spectral interferometry

      Air etalon facilitated simultaneous measurement of group refractive index and thickness using spectral interferometry

      A simple method based on air etalons of a transparent cavity is proposed to simultaneously measure the group refractive index and thickness of a transparent optical plate by spectral domain low coherence interferometry. In this method, only a single beam path is needed in contrast to the two beam paths, the reference and sample arms, of the conventional Michelson interferometer. An empty cavity is first constructed in the beam path by two glass plates. Then the transparent plate under test is inserted into the cavity, so that two air gaps are formed in the cavity. A beam of light of ...

      Read Full Article
    17. Non-destructive stress profile determination in chemically tempered glass

      Non-destructive stress profile determination in chemically tempered glass

      Apparatus, systems and methods for improving strength of thin cover glass for electronic devices are disclosed. Optical coherence tomography analysis may reveal fine details of a residual stress profile within chemically strengthened cover glass. One or more parameters of chemical strengthening treatments may be adjusted, based upon the analysis of the residual stress profile.

      Read Full Article
    18. Feature of the Week 10/26/14: 3D Polymer Weld Seam Characterization Based on OCT Laser Transmission Welding Applications

      Feature of the Week 10/26/14: 3D Polymer Weld Seam Characterization Based on OCT Laser Transmission Welding Applications

      Plastics have low weight but a high weight to strength ratio and a good corrosion resistance allied to a high degree of freedom on its form design. These characteristics lead plastics to be used in several technical systems with high production and application requirements. Herewith the complete production chain of these components as well as their integration in technical systems are also subjected to high standards. The joining of plastics and polymers is an important step in this process chain, as often at this stage pre-processed parts with a high added value are machined. Especially in high performance production chains ...

      Read Full Article
    19. Optical coherence tomography for shape and radius of curvature measurements of deeply curved machined metallic surfaces: a comparison with two-beam laser interferometry

      Optical coherence tomography for shape and radius of curvature measurements of deeply curved machined metallic surfaces: a comparison with two-beam laser interferometry

      An application of optical coherence tomography (OCT) for measuring shape and the radius of curvature of deeply curved metallic surfaces in precision mechanical components is demonstrated. Measurements carried out by OCT technique on concave and convex hemispherical metallic surfaces generated by diamond turning process is presented. The technique is compared with a two-beam laser interferometric method for determinations of shape errors and radius of curvature. It is shown that OCT is a useful tool for three-dimensional shape determinations for deeply curved surfaces such as hemispheres and has advantages over two-beam laser interferometric method.

      Read Full Article
      Mentions: K. Divakar Rao
    20. Metrology research on PDMS phantoms for evaluating resolution performance of OCT systems

      Metrology research on PDMS phantoms for evaluating resolution performance of OCT systems

      Imaging resolution, an important performance parameter of OCT systems, can be evaluated by suitable point spread function (PSF) phantoms. In this paper, we propose an innovative method to prepare PSF phantoms by mixing polystyrene microspheres of standard sizes with transparent polymer - polydimethylsiloxane (PDMS). Detailed procedures as well as specific design are described, and the produced PSF phantoms are employed to verify OCT system resolution performance by analyzing corresponding point spread functions. For comparison, images of the standard-size microspheres are provided by measuring the PSF phantoms with optical microscope.

      Read Full Article
    21. Feature Of The Week 9/21/14: National University of Singapore Investigates OCT as a Tool for Characterization of Complex Biological Surfaces Including Morphology of Crab Shells

      Feature Of The Week 9/21/14: National University of Singapore Investigates OCT as a Tool for Characterization of Complex Biological Surfaces Including Morphology of Crab Shells

      The advent of scanning electron microscopy has facilitated our understanding of the In recent years, there has been a growing interest in the study of natural biological surfaces in the search for novel solutions in surface engineering design from nature. Most methods for surface imaging of natural biological samples are however, sacrificial and require that samples be sectioned and prepared for characterization. One example is the use of the scanning electron microscope (SEM) to obtain detailed images of microtopography, where a section of the specimen is cut and sputter coated with electrically conductive material like gold or platinum for scanning ...

      Read Full Article
    22. 3D Polymer Weld Seam Characterization Based on Optical Coherence Tomography for Laser Transmission Welding Applications

      3D Polymer Weld Seam Characterization Based on Optical Coherence Tomography for Laser Transmission Welding Applications

      Laser transmission welding is an established single-stage plastic joining process, which enables hermetically sealed joints under the workpiece surface. The process requires joining partners with proper degrees of transmission and absorption to the processing wavelength. For reaching a stable process an in-process quality assurance is very valuable. Current monitoring systems have a limited usage, as no quantitative information of the weld itself is obtained without its destruction. In medical and pharmaceutical applications a weld with leakage is e.g. unacceptable. The main objective of this paper is the presentation of the optical coherence tomography as a tool for the quality ...

      Read Full Article
    23. Two-dimensional optical coherence tomography for real-time structural dynamical characterization

      Two-dimensional optical coherence tomography for real-time structural dynamical characterization

      We present a two-dimensional optical coherence vibration tomography (2DOCVT) system with an ultra-precision displacement resolution of ~0.1 nm that is capable of in site real-time absolute displacement measurement of structural line vibrations. Experimental results of sinusoidal, sweep and impulse vibrations were reported. The key figures of merit such as the 2DOCVT system could obtain fast line vibration measurement without scanning and it also could be used to capture structural modal parameters in one single impulse excitation measurement without any vibration excitation input information, making it attractive for the application in low-frequency vibration measurement and response-only modal analysis.

      Read Full Article
    24. Second International Symposium on Optical Coherence Tomography for Non-Destructive Testing March 25th, 2015

      Second International Symposium on Optical Coherence Tomography for Non-Destructive Testing March 25th, 2015

      Optical Coherence Tomography (OCT) is a well-qualified tool for contactless, structural imaging of various samples. Already well-established in medical applications, in the last years the usage of OCT has been extended to diverse fields of non-destructive testing as well. In course of this progress, various devices for industrial measurements, process monitoring and research were developed. With our invitation to the second international symposium on Optical Coherence Tomography for Non-Destructive Testing OCT4NDT we like to settle a tradition from the well-founded forum for the OCT community. The symposium is intended to serve as a platform enabling an exchange of information on ...

      Read Full Article
      Mentions: RECENDT
    1-24 of 200 1 2 3 4 5 6 7 8 9 »
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks
  2. Popular Articles

  3. Organizations in the News

    1. (2 articles) Nottingham Trent University
    2. (2 articles) University of Southampton
    3. (1 articles) Kyungpook National University
    4. (1 articles) University of Twente
  4. People in the News

    1. (1 articles) Jeehyun Kim
    2. (1 articles) Haida Liang