1. Articles in category: NDE/NDT

    1-24 of 278 1 2 3 4 ... 10 11 12 »
    1. Advanced analysis of domain walls in Mg doped LiNbO3 crystals with high resolution OCT

      Advanced analysis of domain walls in Mg doped LiNbO3 crystals with high resolution OCT

      The structure of domain walls (DW) in ferroelectric media is of great interest as this material is used for frequency doublers and other applications. We show that the structure of the DWs can nicely be visualized by high resolution optical coherence tomography (OCT). While the high group refractive index of lithium niobate allows a resolution much better than 1 µm, the large dispersion can blur the image and has to be compensated. Therefore, we developed an adaptive dispersion compensation algorithm based on maximizing the intensity of the DWs. By measuring a group of DWs, the mean period of the DWs ...

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    2. Analyzing Car Paint Through Optical Coherence Tomography

      Analyzing Car Paint Through Optical Coherence Tomography

      Researchers at the University of Liverpool in the UK have demonstrated for the first time how the medical imaging technique optical coherence tomography (OCT) could provide the car industry with a practical way to automatically analyze the distribution and characteristics of the metallic flakes in car paint. Originally a medical imaging technique Medical professionals routinely use optical coherence tomography, invented in 1991, for applications such as diagnosing eye diseases. Meanwhile, OCT is advancing into new biomedical applications and is being explored as a tool for improving manufacturing and industrial processes. The Liverpool team reports that moving their OCT technique from ...

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    3. Non-destructive analysis of flake properties in automotive paints with full-field optical coherence tomography and 3D segmentation

      Non-destructive analysis of flake properties in automotive paints with full-field optical coherence tomography and 3D segmentation

      Automotive coating systems are designed to protect vehicle bodies from corrosion and enhance their aesthetic value. The number, size and orientation of small metallic flakes in the base coat of the paint has a significant effect on the appearance of automotive bodies. It is important for quality assurance (QA) to be able to measure the properties of these small flakes, which are approximately 10 μm in radius, yet current QA techniques are limited to measuring layer thickness. We design and develop a time-domain (TD) full-field (FF) optical coherence tomography (OCT) system to scan automotive panels volumetrically, non-destructively and without contact ...

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    4. Feature Of The Week 07/24/2017: Spectral Domain Optical Coherence Tomography for Non-Destructive Testing of Protection Coatings on Metal Substrates

      Feature Of The Week 07/24/2017: Spectral Domain Optical Coherence Tomography for Non-Destructive Testing of Protection Coatings on Metal Substrates

      Industrial monuments and other artefacts of vanishing industries have to be preserved as cultural heritage. For example, in Germany next year the public subsidy for the mining industry will end and with this the active mining will end as well. The Deutsches Bergbau-Museum in Bochum as one of the largest of its kind and as a research institution of the Leibnitz association is committed to preserve the cultural heritage of the mining industry. Thus it is facing the huge task to conserve a lot of mining industry objects in their actual authentic appearance, ranging from small tools like hammers to ...

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    5. Determination of Coefficient of Thermal Expansion in High Power GaN-Based Light-Emitting Diodes via Optical Coherent Tomography

      Determination of Coefficient of Thermal Expansion in High Power GaN-Based Light-Emitting Diodes via Optical Coherent Tomography

      One of the most challenging issues when operating a high-power light-emitting diode (LED) is to conduct appropriate packaging materials for the reliable thermal management of the entire device. Generally, the considerable amount of heat produced around the junction area of the LED would transfers to the entire device, and causes thermal expansion in the packaging material. It induces strain inevitably, and hinders the output performances and possible applications of high-power LEDs. The coefficient of thermal expansion (CTE) is a physical quantity that indicates the expansion to which value a material will be upon heating. Therefore, as far as an advancement ...

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    6. Viewing a Weld Seam in 360°: New Scan Solution Utilizes OCT Technology to Coaxially Track and Inspect Seams

      Viewing a Weld Seam in 360°: New Scan Solution Utilizes OCT Technology to Coaxially Track and Inspect Seams

      At the Laser World of Photonics tradeshow in Munich, Germany, Blackbird Robotersysteme GmbH (acknowledged remote welding expert and SCANLAB GmbH associate company) will present an entirely new scan solution prototype with integrated distance sensor. Based on optical coherence tomography (OCT), the system detects and measures 3D laser weld seam topographies in high resolution. This is particularly advantageous for industrial system integrators and users looking to secure process safety and comprehensive quality management without a separate monitoring solution. In healthcare OCT has proven itself as an examination technique for opththamology, skin analysis, cancer diagnosis and more. For patients, this optical measurement ...

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    7. Feature Of The Week 07/07/2017: Tomographical process monitoring of laser transmission welding with OCT

      Feature Of The Week 07/07/2017: Tomographical process monitoring of laser transmission welding with OCT

      Laser transmission welding as a contactless and locally limited joining technique is well-established in different production areas. It is used in a variety of demanding applications like for example parts which require a particle-free joining process. Sensitive parts demand a joining technique which does not affect the inner components. The welding process itself faces higher requirements concerning for example tightness of the weld joint or cleanliness of the produced part (no material must impurify the part during the process). During the laser transmission welding process the laser radiation is locally focused on an absorbing surface. The joining is performed between ...

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    8. Pharmaceutical film coating catalogue for spectral-domain optical coherence tomography

      Pharmaceutical film coating catalogue for spectral-domain optical coherence tomography

      Optical coherence tomography (OCT) has recently been demonstrated to measure the film coating thickness of pharmaceutical tablets and pellets directly. The results enable the analysis of inter- and intra-tablet coating variability at an off-line and in-line setting. To date, only a few coating formulations have been tried and there is very little information on the applicability of OCT to other coatings. As it is well documented that optical methods including OCT are prone to scattering leading to limited penetration, some pharmaceutical coatings may not be measurable altogether. This study presents OCT measurements of 22 different common coatings for the assessment ...

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    9. Axsun Hopes to Break Into the 3D Printing Market | 3D Print Plan

      Axsun Hopes to Break Into the 3D Printing Market | 3D Print Plan

      Axsun is a 100-person Boston-based company that specializes in “advanced photonics”, a science involving light and microscopic devices. Their technology uses “Optical Coherence Tomography (OCT)” in a way that could benefit 3D print operations. This technology is well-established in the medical community, where it is used to capture highly detailed images of sub-surface structures in transparent or translucent materials. Normally, this is used to “see” into patients for medical diagnoses. Specialized lasers provide the imaging through materials. However, the theory is that it could also be used in 3D printing. Axsun’s proposition is that this technology could be added ...

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    10. Structural Analysis of Polymer Composites Using Spectral Domain Optical Coherence Tomography

      Structural Analysis of Polymer Composites Using Spectral Domain Optical Coherence Tomography

      The structural analysis of nylon/graphene oxide (NY/GO) and polyetherblockamide/ trisilinolphenyl-polyhederal oligomeric silsesquioxane (PEBA/t-POSS) composites were performed using high-resolution spectral domain optical coherence tomography (SD-OCT). This optical technology revealed both cross-sectional, as well as sub-layer depth information of sample. The non-destructive real-time imaging demonstrated the nature of defects in the composites. The thickness and location of each defect point in the composites were measured using A-scan analysis on the SD-OCT images. The cross-sectional and volumetric images clearly demonstrate the effectiveness of SD-OCT for composite research, as well as the for industrial quality assurance of polymer materials.

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    11. Spectral Domain Optical Coherence Tomography for Non-Destructive Testing of Protection Coatings on Metal Substrates

      Spectral Domain Optical Coherence Tomography for Non-Destructive Testing of Protection Coatings on Metal Substrates

      In this paper we demonstrate that optical coherence tomography (OCT) is a powerful tool for the non-destructive investigation of transparent coatings on metal substrates. We show that OCT provides additional information which the common practice electrical impedance spectroscopy (EIS) cannot supply. First, coating layer thicknesses were measured and compared with reference measurements using a magnetic inductive (MI) measurement technique. After this validation of the OCT measurements, a customized sectioned sample was created to test the possibility to measure coating thicknesses with underlying corrosion, which cannot be analyzed accurately by MI or EIS measurements. Finally, we demonstrate the benefit of OCT ...

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    12. Scan-Less Line Field Optical Coherence Tomography, with Automatic Image Segmentation, as a Measurement Tool for Automotive Coatings

      Scan-Less Line Field Optical Coherence Tomography, with Automatic Image Segmentation, as a Measurement Tool for Automotive Coatings

      The measurement of the thicknesses of layers is important for the quality assurance of industrial coating systems. Current measurement techniques only provide a limited amount of information. Here, we show that spectral domain Line Field (LF) Optical Coherence Tomography (OCT) is able to return to the user a cross sectional B-Scan image in a single shot with no mechanical moving parts. To reliably extract layer thicknesses from such images of automotive paint systems, we present an automatic graph search image segmentation algorithm. To show that the algorithm works independently of the OCT device, the measurements are repeated with a separate ...

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      Mentions: Yalin Zheng
    13. Optical Coherence Tomography Reveals Coral Structure, Response to Environmental Stress

      Optical Coherence Tomography Reveals Coral Structure, Response to Environmental Stress

      Brightfield imaging and epifluorescence microscopy have been used to observe living coral, but with limited depth and areal resolution due to the opaque coral tissue, which is composed of different cell layers, and diffuse backscatter from the underlying coral skeleton. Use of visible light for these observations can also impact the coral, e.g., by stimulating photosynthesis or by exposure to potentially harmful UV and blue light. Employing optical coherence tomography (OCT), researchers at the Faculty of Science, University of Copenhagen , have found a way around these obstacles. Michael Kühl of the Department of Biology explained, “OCT is an ...

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    14. Secure fingerprint identification based on structural and microangiographic optical coherence tomography

      Secure fingerprint identification based on structural and microangiographic optical coherence tomography

      Optical coherence tomography (OCT) allows noncontact acquisition of fingerprints and hence is a highly promising technology in the field of biometrics. OCT can be used to acquire both structural and microangiographic images of fingerprints. Microangiographic OCT derives its contrast from the blood flow in the vasculature of viable skin tissue, and microangiographic fingerprint imaging is inherently immune to fake fingerprint attack. Therefore, dual-modality (structural and microangiographic) OCT imaging of fingerprints will enable more secure acquisition of biometric data, which has not been investigated before. Our study on fingerprint identification based on structural and microangiographic OCT imaging is, we believe, highly ...

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    15. Feature of the Week 01/23/2017: In-Situ Biofouling Assessment in Spacer Filled Channels Using Optical Coherence Tomography - Biofilm Thickness Mapping

      Feature of the Week 01/23/2017: In-Situ Biofouling Assessment in Spacer Filled Channels Using Optical Coherence Tomography - Biofilm Thickness Mapping

      Biofouling is a one of the major problem in membrane filtration systems. Biofouling leads to performance losses such as reduction of permeate flux, reducing permeate quality, increase in energy consumption, and decreasing of membrane lifetime. Conventional techniques to investigate biofouling involve taking samples by physically breaking up membrane modules and analyzing biofilm build-up. However, this can disrupt the natural process behind biofouling. Therefore, those methods are not able to provide on-line and real-time information about biofilm development. Our research is focused in studying the biofilm development in membrane filtration systems in-situ online under continuous operation using Optical Coherence Tomography (OCT ...

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    16. In-situ biofouling assessment in spacer filled channels using optical coherence tomography (OCT): 3D biofilm thickness mapping

      In-situ biofouling assessment in spacer filled channels using optical coherence tomography (OCT): 3D biofilm thickness mapping

      Membrane systems for water purification can be seriously hampered by biofouling. The use of optical coherence tomography (OCT) to investigate biofilms in membrane systems has recently increased due to the ability to do the characterization in-situ and non-destructively. The OCT biofilm thickness map is presented for the first time as a tool to assess biofilm spatial distribution on a surface. The map allows the visualization and evaluation of the biofilm formation and growth in membrane filtration systems through the use of a false color scale. The biofilm development was monitored with OCT to evaluate the suitability of the proposed approach ...

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    17. Optical sensing method to analyze germination rate of Capsicum annum seeds treated with growth-promoting chemical compounds using optical coherence tomography

      Optical sensing method to analyze germination rate of Capsicum annum seeds treated with growth-promoting chemical compounds using optical coherence tomography

      Seed germination rate differs based on chemical treatments, and nondestructive measurements of germination rate have become an essential requirement in the field of agriculture. Seed scientists and other biologists are interested in optical sensing technologies-based biological discoveries due to nondestructive detection capability. Optical coherence tomography (OCT) has recently emerged as a powerful method for biological and plant material discoveries. We report an extended application of OCT by monitoring the germination rate acceleration of chemically primed seeds. To validate the versatility of the method, Capsicum annum seeds were primed using three chemical compounds: sterile distilled water (SDW), butandiol, and 1-hexadecene. Monitoring ...

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    18. Noncontact three-dimensional quantitative profiling of fast aspheric lenses by optical coherence tomography

      Noncontact three-dimensional quantitative profiling of fast aspheric lenses by optical coherence tomography

      The use of optical coherence tomography (OCT) for noncontact three-dimensional aspheric lens profiling and retrieval of aspheric surface parameters is demonstrated. Two commercially available aspheric lenses with different focal length-to-diameter ratio have been imaged using OCT, and the measured optical path length distribution has been least square fitted with the aspheric lens surface retrieving the radius of curvature, aspheric constant, and conic constants. The refractive index of these lenses has also been measured referencing with a standard Zerodur glass flat. The fitted aspheric surface coefficients of the lenses are in close agreement with the manufacturer’s values, thus, envisaging the ...

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      Mentions: K. Divakar Rao
    19. Measurement of the inter-tablet coating uniformity of a pharmaceutical pan coating process with combined terahertz and optical coherence tomography in-line sensing

      Measurement of the inter-tablet coating uniformity of a pharmaceutical pan coating process with combined terahertz and optical coherence tomography in-line sensing

      We present in-line coating thickness measurements acquired simultaneously using two independent sensing modalities: terahertz pulsed imaging (TPI) and optical coherence tomography (OCT). Both techniques are sufficiently fast to resolve the coating thickness of individual pharmaceutical tablets in-situ during the film coating operation and both techniques are direct structural imaging techniques that do not require multivariate calibration. The TPI sensor is suitable to measure coatings greater than 50 μm and can penetrate through thick coatings even in the presence of pigments over a wide range of excipients. Due to the long wavelength, terahertz radiation is not affected by scattering from dust ...

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    20. Effects of spacer orientations on the cake formation during membrane fouling: Quantitative analysis based on 3D OCT imaging

      Effects of spacer orientations on the cake formation during membrane fouling: Quantitative analysis based on 3D OCT imaging

      Spacer design plays an important role in improving the performance of membrane processes for water/wastewater treatment. This work focused on a fundamental issue of spacer design, i.e., investigating the effects of spacer orientations on the fouling behavior during a membrane process. A series of fouling experiments with different spacer orientation were carried out to in situ characterize the formation of a cake layer in a spacer unit cell via 3D optical coherence tomography (OCT) imaging. The cake layers formed at different times were digitalized for quantitatively analyzing the variation in the cake morphology as a function of time ...

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    21. Non-invasive method and apparatus for screening high-quality seeds

      Non-invasive method and apparatus for screening high-quality seeds

      Disclosed is a method and apparatus for the non-invasive selection of high-quality seeds, based on optical coherence tomography, by which pathogen-infected and pathogen-free seeds can be discriminated in a non-invasive manner. The apparatus is operated by the processes of scanning a seed of diagnostic interest in a non-invasive manner using an optical coherence tomographic unit; processing interference signals of the scanned tomographic images to produce tomographic image data of the seed of diagnostic interest; analyzing the tomographic image data; comparing the analyzed tomographic image data with preset reference tomographic image data; diagnosing the seed of diagnostic interest as a pathogen-infected ...

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    22. Investigating Intra-Tablet Coating Uniformity With Spectral-Domain Optical Coherence Tomography

      Investigating Intra-Tablet Coating Uniformity With Spectral-Domain Optical Coherence Tomography

      Spectral domain optical coherence tomography (SD-OCT) has recently attracted a lot of interest in the pharmaceutical industry as a fast and non-destructive modality for direct quantification of thin film coatings that cannot easily be resolved with other techniques. While previous studies with SD-OCT have estimated the intra-tablet coating uniformity, the estimates were based on limited number of B-scans. In order to obtain a more accurate estimate, a greater number of B-scans are required that can quickly lead to an overwhelming amount of data. To better manage the data so as to generate a more accurate representation of the intra-tablet coating ...

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    23. Fast Industrial Inspection of Optical Thin Film Using Optical Coherence Tomography

      Fast Industrial Inspection of Optical Thin Film Using Optical Coherence Tomography

      An application of spectral domain optical coherence tomography (SD-OCT) was demonstrated for a fast industrial inspection of an optical thin film panel. An optical thin film sample similar to a liquid crystal display (LCD) panel was examined. Two identical SD-OCT systems were utilized for parallel scanning of a complete sample in half time. Dual OCT inspection heads were utilized for transverse (fast) scanning, while a stable linear motorized translational stage was used for lateral (slow) scanning. The cross-sectional and volumetric images of an optical thin film sample were acquired to detect the defects in glass and other layers that are ...

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    24. Automated Internal Classification of Beadless Chinese ZhuJi Fleshwater Pearls based on Optical Coherence Tomography Images

      Automated Internal Classification of Beadless Chinese ZhuJi Fleshwater Pearls based on Optical Coherence Tomography Images

      Optical coherence tomography (OCT) has been applied to inspect the internal defect of beadless Chinese ZhuJi fleshwater pearls. A novel fully automated algorithm is proposed to classify between normal and defective sub-layer in nacre layer. Our algorithm utilizes the graph segmentation approach to estimate the up and down boundaries of defect sub-layers from flattened and cropped image, and also proposes the strategy for edge and weight construction in segmentation process. The vertical gradients of boundary pixels are used to make grading decision. The algorithm is tested by typical pearl samples, and achieves 100% classification accuracy. The experiment result shows the ...

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    1-24 of 278 1 2 3 4 ... 10 11 12 »
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