1. Articles in category: NDE/NDT

    1-24 of 329 1 2 3 4 ... 12 13 14 »
    1. Determination of mechanical properties of biofilms by modeling the deformation measured using optical coherence tomography

      Determination of mechanical properties of biofilms by modeling the deformation measured using optical coherence tomography

      The advantage of using non-invasive imaging such as optical coherence tomography (OCT) to asses material properties from deformed biofilm geometries can be compromised by the assumptions made on fluid forces acting on the biofilm. This study developed a method for the determination of elastic properties of biofilms by modelling the biofilm deformation recorded by OCT imaging with poroelastic fluid-structure interaction computations. Two-dimensional biofilm geometries were extracted from OCT scans of non-deformed and deformed structures as a result of hydrodynamic loading. The biofilm geometries were implemented in a model coupling fluid dynamics with elastic solid mechanics and Darcy flow in the ...

      Read Full Article
    2. Feature Of The Week 08/31/2018: Spectroscopic Characterization of Si/Mo Thin-film Stack at Extreme Ultraviolet Range

      Feature Of The Week 08/31/2018: Spectroscopic Characterization of Si/Mo Thin-film Stack at Extreme Ultraviolet Range

      Using extreme ultraviolet (EUV) radiation for nanoscale imaging has recently seen much interest. As actinic patterned mask inspection tools are not available, chipmakers have to rely on wafer inspection to identify mask defects. To fulfill the requirements of mask inspection, EUV sources with high brightness, high stability (spatial and temporal), and cost effectiveness are needed. In a laser-produced-plasma (LPP) generated EUV system, a high-intensity laser beam is focused onto a tin target to form a hot plasma, which emits ultraviolet light. In this study, a fiber-laser excitation source was used to generate stable 13.5-nm EUV for spectroscopic optical coherence ...

      Read Full Article
    3. Characterisation of textured surfaces under a laminar flow by Optical Coherence Tomography (Thesis)

      Characterisation of textured surfaces under a laminar flow by Optical Coherence Tomography (Thesis)

      Textured surfaces are present everywhere in nature and in our daily life, interacting constantly with a flow. In this report, we focus on how a textured surface with pillars responds to a laminar flow inside a confined channel. The study is mainly focused on the measurements of the bending of the pillars and of the velocity field, using optical coherence tomography. The potential of this technique, which is not very common in microfluidics, is explored here to characterise our system and its limits are discussed. The measurements of the bending and of the velocity field allow to get the value ...

      Read Full Article
    4. Integrating optical coherence tomography with gravimetric and video analysis (OCT-Gravimetry-Video method) for studying the drying process of polystyrene latex system

      Integrating optical coherence tomography with gravimetric and video analysis (OCT-Gravimetry-Video method) for studying the drying process of polystyrene latex system

      Latex, an aqueous dispersion of sub-micron polymer particles, is widely used as polymer binder in waterborne coatings and adhesives. Drying of a latex is inhomogeneous, during which the spatial distribution of particles is non-uniform and changes with time, usually resulting in a compromise of the integrity of a dried film. To study drying inhomogeneity of latex, we developed a system integrating optical coherence tomography (OCT) with gravimetric and video analysis (OCT-Gravimetry-Video method) to non-destructively monitor the drying process of non-film-forming latexes consisting of hard polystyrene spheres over time. OCT structural and speckle images of the latex’s internal structure show ...

      Read Full Article
    5. Effect of biofilm structural deformation on hydraulic resistance during ultrafiltration: A numerical and experimental study

      Effect of biofilm structural deformation on hydraulic resistance during ultrafiltration: A numerical and experimental study

      Biofilm formation in membrane systems negatively impacts the filtration system performances. This study evaluated how biofilm compression driven by permeate flow increases the hydraulic resistance and leads to reduction in permeate flux. We analysed the effect of biofilm compression on hydraulic resistance and permeate flux through computational models supported by experimental data. Biofilms with homogeneous surface structure were subjected to step-wise changes in flux and transmembrane pressure during compression and relaxation tests. Biofilm thickness under applied forces was measured non-invasively in-situ using optical coherence tomography (OCT). A numerical model of poroelasticity, which couples water flow through the biofilm with biofilm ...

      Read Full Article
    6. Optical Coherence Tomography for NDE (Book Chapter)

      Optical Coherence Tomography for NDE (Book Chapter)

      Optical coherence tomography (OCT) is a noninvasive, high-resolution, interferometric imaging modality using near-infrared light to acquire cross sections and three-dimensional images of the subsurface microstructure of samples. Because of the rapid enhancement of OCT with respect to acquisition speed and axial resolution over the past years, OCT is becoming more and more attractive for applications in nondestructive testing and evaluation. In this chapter, a brief introduction to the technique and the instrumentation is first given, followed by an overview of application of OCT in NDE reported so far.

      Read Full Article
    7. Spectroscopic characterization of Si/Mo thin-film stack at extreme ultraviolet range

      Spectroscopic characterization of Si/Mo thin-film stack at extreme ultraviolet range

      A noninvasive method for characterizing Si/Mo thin-film stack thickness and its complex transfer function using common-path optical coherence tomography is proposed, analyzed, and experimentally demonstrated. A laser-produced plasma (LPP)-based extreme ultraviolet (EUV) source was excited by a four-stage nanosecond Yb:fiber laser amplifier with a pulse energy of 1.01 mJ. The tabletop LPP EUV source was compact and stable for generating the EUV interference fringes. The measured complex transfer function of the Si/Mo stack was verified near the pristine 13.5-nm wavelength range.

      Read Full Article
    8. Non-Destructive Classification of Diversely Stained Capsicum annuum Seed Specimens of Different Cultivars Using Near-Infrared Imaging Based Optical Intensity Detection

      Non-Destructive Classification of Diversely Stained Capsicum annuum Seed Specimens of Different Cultivars Using Near-Infrared Imaging Based Optical Intensity Detection

      The non-destructive classification of plant materials using optical inspection techniques has been gaining much recent attention in the field of agriculture research. Among them, a near-infrared (NIR) imaging method called optical coherence tomography (OCT) has become a well-known agricultural inspection tool since the last decade. Here we investigated the non-destructive identification capability of OCT to classify diversely stained (with various staining agents) Capsicum annuum seed specimens of different cultivars. A swept source (SS-OCT) system with a spectral band of 1310 nm was used to image unstained control C. annuum seeds along with diversely stained Capsicum seeds, belonging to different cultivar ...

      Read Full Article
    9. Microscale light management and inherent optical properties of intact corals studied with optical coherence tomography

      Microscale light management and inherent optical properties of intact corals studied with optical coherence tomography

      Coral reefs are highly productive photosynthetic systems and coral optics studies suggest that such high efficiency is due to optimised light scattering by coral tissue and skeleton. Here, we characterise the inherent optical properties, i.e., the scattering coefficient, μ s , and the anisotropy of scattering, g , of 8 intact coral species using optical coherence tomography (OCT). Specifically, we describe light scattering by coral skeletons, coenoarc tissues, polyp tentacles and areas covered by fluorescent pigments (FP). Our results reveal that light scattering between coral species ranges from μ s = 3 mm -1 ( Stylophora pistillata ) to μ s = 25 mm -1 ( Echinopora lamelosa ). For ...

      Read Full Article
    10. Depth-resolved measurement of the compression displacement fields on the front and rear surfaces of an epoxy sample

      Depth-resolved measurement of the compression displacement fields on the front and rear surfaces of an epoxy sample

      Compression is one of the typical parameters measured in material mechanics. In this research, the compression displacement fields on the front and rear surfaces of an epoxy sample are measured by using a tilt depth-resolved wavenumber-scanning Michelson interferometer. The light source is a distributed feedback laser diode, the wavenumber of which can be modulated to about 1.017 × 104 m–1 by the temperature without mode hopping. A random-sampling Fourier transform is designed to evaluate the phase differences before and after the applied loads. Experimental results show that the depth-resolved measurement of the compression displacement field is of high accuracy ...

      Read Full Article
    11. Non-destructive and non-contact measurement of semiconductor optical waveguide using optical coherence tomography with a visible broadband light source

      Non-destructive and non-contact measurement of semiconductor optical waveguide using optical coherence tomography with a visible broadband light source

      We demonstrated non-destructive and non-contact measurement of semiconductor optical waveguide using optical coherence tomography with a visible broadband light source (vis-OCT). Vis-OCT can provide high axial and lateral resolutions of less than 1 µm, which were effective for measurement of optical waveguides with several-micrometer structure. We obtained cross-sectional images of ridge-type optical waveguides (RWGs) fabricated as test samples and measured the height and width of the RWGs. The height and width measured by vis-OCT were similar to these values measured by scanning electron microscopy. These results indicated that vis-OCT enables measurement of the height and width of optical waveguides without ...

      Read Full Article
    12. Bacterial inactivation and in situ monitoring of biofilm development on graphene oxide membrane using optical coherence tomography

      Bacterial inactivation and in situ monitoring of biofilm development on graphene oxide membrane using optical coherence tomography

      In an attempt to advance GO-based environmental applications, herein we probed the anti-biofouling properties and mechanisms of graphene oxide (GO) surface coating. A flexible and mechanically stable GO membrane was fabricated using vacuum filtration technique and its ability to inactivate bacterial growth and subsequent biofilm formation was investigated. Our preliminary results authenticate that the GO membrane, owing to its unique physicochemical surface properties, exhibits superior antibacterial activity against planktonic cell proliferation. An optical coherence tomography (OCT)-based nondestructive in situ monitoring of bacterial biofilm evolution and behavior revealed that the GO surface initially inhibited biofilm growth for 24 h under ...

      Read Full Article
    13. Evaluation of fouling in nanofiltration for desalination using a resistance-in-series model and optical coherence tomography

      Evaluation of fouling in nanofiltration for desalination using a resistance-in-series model and optical coherence tomography

      Resistance-in-series models have been applied to investigate fouling behavior. However, it is difficult to model the influence of morphology on fouling behavior because resistance is indirectly calculated from the water flux and transmembrane pressure. In this study, optical coherence tomography (OCT) was applied to evaluate the resistance of the fouling layer based on fouling morphology. Sodium alginate, humic acid, and bovine serum albumin (BSA) with high salts concentrations (conductivity: 23 mS/cm) were used as model foulants. At the same total fouling resistance, BSA showed the highest cake layer thickness (BSA (114.5 μm) > humic acid (53.5 μm) > sodium ...

      Read Full Article
    14. Quality assessment of the optical thin films using line field spectral domain optical coherence tomography

      Quality assessment of the optical thin films using line field spectral domain optical coherence tomography

      Cross-sectional and three-dimensional images show the effectiveness of the system. In this study, the industrial inspection of optical thin film on touch screen panels was demonstrated using line field spectral domain optical coherence tomography. The conventional Fourier domain optical coherence tomography system requires a single scanner for two-dimensional cross-sectional images and two scanners for volumetric images. Our developed line field spectral domain optical coherence tomography has the advantage of needing only a single scanner for volumetric images, while two-dimensional cross-sectional images are obtained by the parallel acquisition of an illuminated line on a sample using an area camera. Further, the ...

      Read Full Article
    15. In vivo automated quantification of quality of apples during storage using optical coherence tomography images

      In vivo automated quantification of quality of apples during storage using optical coherence tomography images

      Moisture content is an important feature of fruits and vegetables. As 80% of apple content is water, so decreasing the moisture content will degrade the quality of apples (Golden Delicious). The computational and texture features of the apples were extracted from optical coherence tomography (OCT) images. A support vector machine with a Gaussian kernel model was used to perform automated classification. To evaluate the quality of wax coated apples during storage in vivo , our proposed method opens up the possibility of fully automated quantitative analysis based on the morphological features of apples. Our results demonstrate that the analysis of the ...

      Read Full Article
    16. Evaluating the effect of different draw solutes in a baffled osmotic membrane bioreactor-microfiltration using optical coherence tomography with real wastewate

      Evaluating the effect of different draw solutes in a baffled osmotic membrane bioreactor-microfiltration using optical coherence tomography with real wastewate

      This study investigated the performance of an integrated osmotic and microfiltration membrane bioreactor for real sewage employing baffles in the reactor. To study the biofouling development on forward osmosis membranes optical coherence tomography (OCT) technique was employed. On-line monitoring of biofilm growth on a flat sheet cellulose triacetate forward osmosis (CTA-FO) membrane was conducted for 21 days. Further, the process performance was evaluated in terms of water flux, organic and nutrient removal, microbial activity in terms of soluble microbial products (SMP) and extracellular polymeric substance (EPS), and floc size. The measured biofouling layer thickness was in the order sodium chloride ...

      Read Full Article
    17. In situ biofilm quantification in Bioelectrochemical Systems using Optical Coherence Tomography

      In situ biofilm quantification in Bioelectrochemical Systems using Optical Coherence Tomography

      Detailed studying of microbial growth in bioelectrochemical systems is required for their proper design and operation. Here we report on the use of Optical Coherence Tomography (OCT) as a tool for in situ and non‐invasive quantification of biofilm growth on electrodes (bioanodes). An experimental platform is designed and described in which transparent electrodes are used to allow for real‐time, three‐dimensional biofilm imaging. The accuracy and precision of the developed method is assessed by relating OCT results to well‐established standards for biofilm quantification (COD and Total N) and show high correspondence to these standards. Biofilm thickness as ...

      Read Full Article
    18. Understanding and improving optical coherence tomography imaging depth in selective laser sintering nylon 12 parts and powder

      Understanding and improving optical coherence tomography imaging depth in selective laser sintering nylon 12 parts and powder

      Optical coherence tomography (OCT) has shown promise as a process sensor in selective laser sintering (SLS) due to its ability to yield depth-resolved data not attainable with conventional sensors. However, OCT images of nylon 12 powder and nylon 12 components fabricated via SLS contain artifacts that have not been previously investigated in the literature. A better understanding of light interactions with SLS powder and components is foundational for further research expanding the utility of OCT imaging in SLS and other additive manufacturing (AM) sensing applications. Specifically, in this work, nylon powder and sintered parts were imaged in air and in ...

      Read Full Article
    19. Microdefect identification in polymers by mapping depth-resolved phase-difference distributions using optical coherence tomography

      Microdefect identification in polymers by mapping depth-resolved phase-difference distributions using optical coherence tomography

      A novel method for the identification of microdefects in transparent or semi-transparent polymers and polymer composites is established, which maps the depth-resolved phase-difference distribution during polymer deformation using optical coherence tomography (OCT), and detects internal microdefects using the defect-induced phase-difference-distribution anomalies. For validation, epoxy resin, silicone rubber and glass fiber-reinforced resin matrix composite samples with internal defects with different dimensions were measured by using a line-field spectral-domain OCT system. Small defects, which could not be observed from the cross-sectional images, were identified from the measured phase-difference distributions; fibers and microdefects of a similar size in the polymer composites were distinguished ...

      Read Full Article
    20. Loquat Bruise Detection Using Optical Coherence Tomography Based on Microstructural Parameters

      Loquat Bruise Detection Using Optical Coherence Tomography Based on Microstructural Parameters

      Slight postharvest bruises of loquats remarkably affect the quality and shelf life of the fruits, but they are difficult to identify using visual inspection. Sub-surface structural changes in cells caused by mechanical injury or impact can be detected using spectroscopy-based methods from different angles. Optical coherence tomography (OCT), a non-destructive technology, can acquire cross-sectional images to analyze sub-surface structures of loquats, thus offering the potential to identify fruit bruises. This study proposes an automated OCT image processing method for extracting large cells from loquat images, which involves a series of steps including image denoising, boundary detection, filtering, binarization, segmentation, and ...

      Read Full Article
    21. Non-destructive biomechanical testing of tissues using a vibrational optical coherence tomography setup (Thesis)

      Non-destructive biomechanical testing of tissues using a vibrational optical coherence tomography setup (Thesis)

      The mechanical properties of tissues and implants contribute to their physiological functionality, and have been vast areas of research in fields such as Dermatology, Cardiology, Neurology, Ophthalmology, Orthopedics and Urology. Several tests and modalities have been used to measure the mechanical properties of tissues and implants including tensile, compressive, shear, and bending in one or more axial directions. However, majority of these tests are destructive, rendering the material unusable post-testing; whereas most of the non-destructive imaging modalities such as magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR) and ultrasound are costly and have lower spatial resolution. Optical coherence tomography (OCT ...

      Read Full Article
    22. Quantitative discrimination of pearls using polarization-sensitive optical coherence tomography

      Quantitative discrimination of pearls using polarization-sensitive optical coherence tomography

      We propose a robust method that can quantitatively discriminate genuine pearls from imitation ones by introducing the concept of entropy in the polarization-sensitive optical coherence tomography (PS-OCT). Qualitatively, by examining the birefringence properties of the nacre region of pearls with PS-OCT, the genuine pearls can be easily discriminated. To quantify the amount of birefringence formation, however, the concept of phase retardation entropy is introduced, which is expected to have a higher value when a PS-OCT tomogram has more diverse phase retardation values in its histogram. Experimental confirmation demonstrated that the phase retardation entropy of a genuine pearl was always higher ...

      Read Full Article
    23. Optical coherence tomography characterization of femtosecond laser manufactured microfluidic circuits

      Optical coherence tomography characterization of femtosecond laser manufactured microfluidic circuits

      Dimensional characterization of microfluidic circuits were performed using three-dimensional models constructed from OCT images of such circuits. Were fabricated microchannels on the same BK7 glass plate, under different laser ablation conditions and substrate displacement velocity in relation to laser beam. Were used the following combination of energy, from 30 μJ to 60 μJ and velocity from 588 mm/min to 1176 mm/min, at 1 kHz laser repetition rate and 40 fs of pulse duration (FWHM). For OCT imaging we used an OCP930SR (Thorlabs System Inc) with 930 nm central wavelength, 6 μm of lateral and axial resolution, and image ...

      Read Full Article
    1-24 of 329 1 2 3 4 ... 12 13 14 »
  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) Delft University of Technology
    2. (1 articles) National Taiwan University
    3. (1 articles) Dresden University of Technology
    4. (1 articles) Karlsruhe Institute of Technology
  4. People in the News

    1. (1 articles) Julia Walther
    2. (1 articles) Sheng-Lung Huang
    3. (1 articles) Chao Zhou
    4. (1 articles) Yongyang Huang
    5. (1 articles) Edmund Koch
    6. (1 articles) Yin-Wen Lee
    7. (1 articles) Lars Kirsten