1. Articles in category: NDE/NDT

    1-24 of 429 1 2 3 4 ... 16 17 18 »
    1. Introducing the Santec OPS-1000 3D Optical Profiler

      Introducing the Santec OPS-1000 3D Optical Profiler

      Santec introduces the new 3D Optical Profiler, OPS-1000. Designed to support R&D and production environments the OPS-1000 delivers fast, accurate and wide 3D object scans with high sensitivity, capturing surfaces other profilers may miss. A wide system dynamic range of >70dB enables non-contact, high-speed measurements with high accuracy, regardless of shape, material, color or surface condition. Intuitive control software allows the user to quickly configure scan profiles, automate testing, and export the point cloud data for analysis.

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      Mentions: Santec
    2. Monitoring fatigue damage in different CAD/CAM materials: A new approach with optical coherence tomography.

      Monitoring fatigue damage in different CAD/CAM materials: A new approach with optical coherence tomography.

      Purpose: To investigate fatigue damage over time, monolithic posterior computer-aided-designed/computer-aided-manufactured (CAD/CAM) crowns were artificially aged in a mouth-motion-simulator, and damage was monitored with optical coherence tomography (OCT). Methods: Forty-eight crowns were milled of six different CAD/CAM-materials (n=8), including 3Y-TZP (Lava Plus,‘3Y’), 4Y-PSZ (Pritidentamultidisc,‘4Y’), 5Y-PSZ (Prettauanterior,‘5Y’), zirconia-reinforced lithium silicate (CeltraDuo,‘ZLS’), hybrid ceramic (Vita Enamic,‘VE’),and resin composite (BrilliantCrios,‘COM’), and were adhesively luted on CAD/CAM-milled human molars. Specimens were artificially aged in a mouth-motion-simulator (50-500N, 2Hz, 37°C) for a period of 1 million cycles. Before loading and every 250,000 ...

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    3. Correlative infrared optical coherence tomography and hyperspectral chemical imaging

      Correlative infrared optical coherence tomography and hyperspectral chemical imaging

      Optical coherence tomography (OCT) is a high-resolution three-dimensional imaging technique that enables nondestructive measurements of surface and subsurface microstructures. Recent developments of OCT operating in the mid-infrared (MIR) range (around 4 µm) lifted fundamental scattering limitations and initiated applied material research in formerly inaccessible fields. The MIR spectral region, however, is also of great interest for spectroscopy and hyperspectral imaging, which allow highly selective and sensitive chemical studies of materials. In this contribution, we introduce an OCT system (dual-band, central wavelengths of 2 µm and 4 µm) combined with MIR spectroscopy that is implemented as a raster scanning chemical imaging ...

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    4. Surface and Internal Fingerprint Reconstruction from Optical Coherence Tomography through Convolutional Neural Network

      Surface and Internal Fingerprint Reconstruction from Optical Coherence Tomography through Convolutional Neural Network

      Optical coherence tomography (OCT), as a non-destructive and high-resolution fingerprint acquisition technology, is robust against poor skin conditions and resistant to spoof attacks. It measures fingertip information on and beneath skin as 3D volume data, containing the surface fingerprint, internal fingerprint and sweat glands. Various methods have been proposed to extract internal fingerprints, which ignore the inter-slice dependence and often require manually selected parameters. In this paper, a modified U-Net that combines residual learning, bidirectional convolutional long short-term memory and hybrid dilated convolution (denoted as BCL-U Net) for OCT volume data segmentation and two fingerprint reconstruction approaches are proposed. To ...

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    5. Full-Range Line-Field Optical Coherence Tomography for High-Accuracy Measurements of Optical Lens

      Full-Range Line-Field Optical Coherence Tomography for High-Accuracy Measurements of Optical Lens

      A full-range line-field Fourier-domain optical coherence tomography (LF-FDOCT) system with an accuracy at nanoscale was proposed for high-accuracy measurements of optical lens surface profile. The LF surface curve information of optical lens could be obtained in one measurement which does not need point-by-point scanning used in the traditional 1-D FDOCT system. The measurement accuracy of surface profile curve could be improved from micrometer scale to nanoscale by applying spectral center correction method (SCCM) to the complex spectral interferogram. The corrected five phase-shifting (CFPS) method was employed to eliminate the complex-conjugate artifacts and the polychromatic error. The numerical simulation and experiment ...

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    6. Three-dimensional color camera based on optical coherence tomography

      Three-dimensional color camera based on optical coherence tomography

      We propose a 3D color camera to record the moving objects image based on optical coherence tomography (OCT). A precise surface topography map of the object is acquired by OCT, to which, a color image acquired by a CCD, is fused. During OCT scanning, adjacent color images are cross-correlated to compute the offset position of the moving object. The offset position is applied to the OCT to tracking scan the moving object. A 3D topography algorithm is to reconstruct surface topography maps. The affine transform and similarity model are used to match the 2D color image to the surface topography ...

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    7. Physiological, Biochemical and Microstructural Changes in Rice (Oryza sativa L.) under Varying pH Levels

      Physiological, Biochemical and Microstructural Changes in Rice (Oryza sativa L.) under Varying pH Levels

      Soil acidification exerts detrimental effects on rice plant leading to severe reduction in its yield. In the present study, we investigated the physiological, biochemical and microstructural changes in the leaves of rice cultivars, namely, Jhilli Dhan (JD) and Gora Dhan (GD), under varying pH conditions (pH 6.5, 5.5, 4.5 and 3.5). Seedlings were grown at varying pH levels for 14 days under controlled conditions. Root and shoot growth and chlorophyll content were found to be decreased with increasing acidity, whereas electrolyte leakage was increased with increasing acidity. Overall, seedling growth was significantly reduced at pH 3 ...

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    8. Biospeckle optical coherence tomography in speedy visualizing effects of foliar application of plant growth hormone to Chinese chives leaves

      Biospeckle optical coherence tomography in speedy visualizing effects of foliar application of plant growth hormone to Chinese chives leaves

      Objective The aim of this study is to demonstrate the potential of applying the contrast of the speckles obtained as noise in optical coherence tomography (OCT) images to monitor short term activity changes during foliar application of phytohormones to a plant leaf. Plant growth hormone, gibberellic acid (GA 3 ) was sprayed onto the leaf of Chinese chives and after 60 min, OCT images (1 frame: 512 × 2048 pixels) were recorded at ten frames per second for a few tens of seconds. Results Contrast across the temporal axis was calculated for each pixel of the structural images and biospeckle OCT contrast ...

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    9. Optical coherence tomography for characterization of nanocomposite materials (Thesis)

      Optical coherence tomography for characterization of nanocomposite materials (Thesis)

      Nanocomposite materials play an increasingly important role in various application areas, be it in an industrial, medical or everyday environment. The unique properties of nanocomposites go beyond those of conventional composite materials. Because nanoparticles have a high surface-to-volume ratio such as carbon nanotubes, they can reinforce an embedding polymer host matrix mechanically, or they enhance the electrical material conductivity. A major challenge in the development of nanoparticles and nanocomposites is the control of particle size and shape, and of the uniform dispersion of nanoparticles in the host material. Conventional characterization techniques lack either resolution, or can only inspect details of ...

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    10. Optical coherence tomography measurement of capillary filling in porous silicon

      Optical coherence tomography measurement of capillary filling in porous silicon

      The use of nanoporous structures with known morphology allows studying the properties of fluids in conditions of strong spatial confinement. Alternatively, the capillary filling of nanoporous structures with simple fluids provides information on their morphology. When a liquid enters the porous structure there is an increase in the optical path of the porous layer, and measuring this optical path as a function of position and time allows evaluating the filling dynamics of the pores. In this work, we determined the capillary filling dynamics of nanostructured porous silicon (PS) by optical coherence tomography. The high spatial resolution of this technique allows ...

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    11. Absolute depth LIBS-stratigraphy with NoScSiSp-OCT

      Absolute depth LIBS-stratigraphy with NoScSiSp-OCT

      LIBS is a proven method for elemental analysis. It needs little to no sample preparation and relies solely on optical access to the sample. LIBS has therefore been handled as a promising analytical method for layered or structured samples with the potential to replace metallurgic cross-sections followed by SEM/EDX raster screenings. Due to the strong dependency of the ablation process on changing crater geometries, laser fluence, and plasma dynamics ( e.g. laser absorption and scattering by the plasma, material dependent optical depth, reflecting coefficients, scattering processes, etc. ), attributing an absolute depth to the number of laser pulses applied to ...

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    12. Effect of chlorination and pressure flushing of drippers fed by reclaimed wastewater on biofouling

      Effect of chlorination and pressure flushing of drippers fed by reclaimed wastewater on biofouling

      Dripper clogging reduces the performance and service life of a drip irrigation system. The impact of chlorination (1.5 ppm of free chlorine during 1 h application) and pressure flushing (0.18 MPa) on the biofouling of non-pressure-compensating drippers fed by real reclaimed wastewater was studied at lab scale using Optical Coherence Tomography. The effect of these treatments on microbial composition (bacteria and eukaryotes) was also investigated by High-throughput DNA sequencing. Biofouling was mainly observed in inlet, outlet and return areas of the drippers. Chlorination limited biofilm development mainly in the mainstream of the milli-labyrinth channel. It was more efficient ...

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    13. Laser Lens Size Measurement Using Swept-Source Optical Coherence Tomography

      Laser Lens Size Measurement Using Swept-Source Optical Coherence Tomography

      A high-speed, high-resolution swept-source optical coherence tomography (SS-OCT) is presented for focusing lens imaging and a k-domain uniform algorithm is adopted to find the wave number phase equalization. The radius of curvature of the laser focusing lens was obtained using a curve-fitting algorithm. The experimental results demonstrate that the measuring accuracy of the proposed SS-OCT system is higher than the laser confocal microscope.

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    14. Ultrafast-laser ablation of polymer multicore fibers enhances biomedical sensing

      Ultrafast-laser ablation of polymer multicore fibers enhances biomedical sensing

      The next step is to integrate the multipoint-emission fiber, with optimization, in devices to perform a range of biomedical applications such as fluorescence, 2 confocal imaging, 3 photobiomodulation, 4 optical tomography, 5 medical device location, 6 and 3D optical coherence tomography (OCT). 7 The discrete emission of light has potential in medical diagnostics, enabling spectroscopic investigation at many points along a medical device throughout an organ or extended tissue structures. During medical-device placement—for instance, central venous catheter placement—multipoint light emission along the device length could be viewed through the skin. An immediate application of such a fiber is ...

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    15. A Method for the Assessment of Textile Pilling Tendency Using Optical Coherence Tomography

      A Method for the Assessment of Textile Pilling Tendency Using Optical Coherence Tomography

      Pilling is caused by friction pulling and fuzzing the fibers of a material. Pilling is normally evaluated by visually counting the pills on a flat fabric surface. Here, we propose an objective method of pilling assessment, based on the textural characteristics of the fabric shown in optical coherence tomography (OCT) images. The pilling layer is first identified above the fabric surface. The percentage of protruding fiber pixels and Haralick’s textural features are then used as pilling descriptors. Principal component analysis (PCA) is employed to select strongly correlated features and then reduce the feature space dimensionality. The first principal component ...

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    16. Optical coherence tomography with balanced signal strength across the depth for pearl inspection

      Optical coherence tomography with balanced signal strength across the depth for pearl inspection

      Optical coherence tomography (OCT) relies on the reflection of light from structures in different layers to interferometrically reconstruct the volumetric image of the sample. However, light returned from multiple layers suffers from imbalanced attenuation owing to the optical path difference and inhomogeneous tissue absorption. We report an optimization algorithm to improve signal strength in deep tissue for swept-source (SS)-OCT imaging. This algorithm utilizes the attenuation coefficient of consecutive layers within the sample and combines them to compensate for the signal intensity loss from deep tissue. We stacked 170-µm thick cover slides as a standard sample for benchmark testing ...

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    17. Keyhole mapping to enable closed-loop weld penetration depth control for remote laser welding of aluminum components using optical coherence tomography

      Keyhole mapping to enable closed-loop weld penetration depth control for remote laser welding of aluminum components using optical coherence tomography

      Remote laser welding (RLW) combines the positive features of tactile laser welding with additional benefits such as increased processing speed, reduced operational cost and service, and higher process flexibility. A leading challenge preventing the full uptake of RLW technology in industry is the lack of efficient closed loop in-process (CLIP) monitoring and weld quality control solutions. This underpins the need to fuse multiple sensor technologies and data analytics with predictive engineering simulations. Although the development and integration of a variety of sensors covers the radiation spectrum from ultraviolet to far-infrared, the flawless deployment of CLIP solutions is still challenged by ...

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    18. Optical Coherence Tomography and Its Non-medical Applications (Textbook)

      Optical Coherence Tomography and Its Non-medical Applications (Textbook)

      Optical coherence tomography (OCT) is a promising non-invasive non-contact 3D imaging technique that can be used to evaluate and inspect material surfaces, multilayer polymer films, fiber coils, and coatings. OCT can be used for the examination of cultural heritage objects and 3D imaging of microstructures. With subsurface 3D fingerprint imaging capability, OCT could be a valuable tool for enhanci...

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    19. Complementary Use of Active Infrared Thermography and Optical Coherent Tomography in Non-destructive Testing Inspection of Ancient Marquetries

      Complementary Use of Active Infrared Thermography and Optical Coherent Tomography in Non-destructive Testing Inspection of Ancient Marquetries

      Imaging-based inspection techniques have practical advantages in the study and/or rehabilitation of artworks. They provide in some cases internal information on the status of the sample to be inspected. On the one hand, techniques based on active infrared thermography (IRT) are advantageous to obtaining complete images of the inspected parts, although a technical interpretation performed by a team of experts in non-destructive testing (NDT) techniques is needed above all when the target is composed, as in our case, by different materials. On the other hand, optical coherence tomography (OCT) is slow when inspecting complete parts, but it has great ...

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    20. Extended sub-surface imaging in industrial OCT using ‘non-diffracting’ Bessel beams

      Extended sub-surface imaging in industrial OCT using ‘non-diffracting’ Bessel beams

      Optical coherence tomography (OCT) is an imaging technique which can provide sub-surface evaluation of defects in optically compliant components such as those manufactured by polymeric selective laser sintering. In OCT systems, achieving lateral imaging resolutions of <10 µm means that full-depth imaging requires multiple scans due to the limited depth of focus (DOF). We present a study on the application of ‘non-diffracting’ Bessel beams to extend system DOF and enable deeper imaging with a single scan. Such capability expands the potential for OCT as a rapid tool for sub-surface assessment, either in-line or in-process, by greatly reducing acquisition times.

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    21. Improvement of the depth resolution of swept-source THz-OCT for non-destructive inspection

      Improvement of the depth resolution of swept-source THz-OCT for non-destructive inspection

      We construct a terahertz swept source optical coherence tomography system using a continuous-wave diode multiplier source in the 600-GHz band for defect inspection in multilayer objects and evaluate its performance. Using this system, we image a multilayer plastic sample to demonstrate the effectiveness of nondestructive three-dimensional imaging. To enhance the depth resolution, we apply an annihilating filter to the analysis and confirm that two surfaces of a 1-mm-thick plastic plate can be resolved. In addition, the repeatability of measured thicknesses is 0.22 mm. These values are approximately one-half and one-tenth of the resolution achievable by conventional Fourier analysis, respectively.

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    22. Robust and high-security fingerprint recognition system using optical coherence tomography

      Robust and high-security fingerprint recognition system using optical coherence tomography

      Traditional fingerprint recognition systems are vulnerable to attacks, such as the use of artificial fingerprints, and poor performance will be achieved if the captured surface fingerprints are of low-quality. Developing high-security and robust fingerprint recognition systems is of increasing concern in modern society. The introduction of optical coherence tomography (OCT) for fingerprint imaging opens up a new research domain for fingerprint recognition due to its ability to capture the depth information of skin layers. This paper proposes a fingerprint recognition system based on OCT. The research first establishes a database with normal, worn-out, artificial and degraded fingerprints imaged by our ...

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    23. 3D-printed corals could improve bioenergy and help coral reefs

      3D-printed corals could improve bioenergy and help coral reefs

      Researchers from Cambridge University and University of California San Diego have 3D printed coral-inspired structures that are capable of growing dense populations of microscopic algae. Their results, reported in the journal Nature Communications , open the door to new bio-inspired materials and their applications for coral conservation. In the ocean, corals and algae have an intricate symbiotic relationship. The coral provides a host for the algae, while the algae produce sugars to the coral through photosynthesis. This relationship is responsible for one of the most diverse and productive ecosystems on Earth, the coral reef. "Corals are highly efficient at collecting and ...

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    1-24 of 429 1 2 3 4 ... 16 17 18 »
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