1. Articles in category: NDE/NDT

    1-24 of 161 1 2 3 4 5 6 7 »
    1. 3D monitoring of delamination growth in a wind turbine blade composite using optical coherence tomography

      3D monitoring of delamination growth in a wind turbine blade composite using optical coherence tomography

      In this paper, delamination and delamination growth in a glass fiber composite used for the spar webs in wind turbine blades is investigated by optical coherence tomography (OCT). The cross-sectional and volumetric images clearly showed the microstructure and the crack within the specimen. After applying an optimized signal processing algorithm, 3D crack growth measured using OCT were demonstrated for the first time to the best of our knowledge. The crack structures inside the composite material at different stages during the delamination growth were revealed.

      Read Full Article
    2. Low coherence interferometric second harmonic generation microscopy for non-destructive material testing using a broadband 1550 nm fs-fiber laser

      Low coherence interferometric second harmonic generation microscopy for non-destructive material testing using a broadband 1550 nm fs-fiber laser

      In this paper low coherence interferometric second harmonic generation (SHG) imaging is successfully demonstrated using a compact broadband fs-fiber laser operating around 1550 nm. In combination with linear optical coherence microscopy, this SHG technique is tailored for structural and functional investigations of surfaces and subsurface regions of non-biological samples, like corrosion sites formed on metals below organic coatings.

      Read Full Article
    3. Simultaneous detection of optical retardation and axis orientation by polarization-sensitive full-field optical coherence microscopy for material testing

      Simultaneous detection of optical retardation and axis orientation by polarization-sensitive full-field optical coherence microscopy for material testing

      We present a polarization-sensitive full-field optical coherence microscopy modality which is capable of simultaneously delivering depth resolved information on the reflectivity, optical retardation and optical axis orientation. In this way local birefringence, inherent stress–strain fields and optical anisotropies can be visualized with high resolution, as exemplified for various technical material applications.

      Read Full Article
    4. In-Situ Optical Coherence Tomography (OCT) for the Time-Resolved Investigation of Crystallization Processes in Polymers

      In-Situ Optical Coherence Tomography (OCT) for the Time-Resolved Investigation of Crystallization Processes in Polymers

      Optical coherence tomography (OCT) is a low-coherence interferometric imaging method which was developed in the 1990s prevalently in the area of biomedical diagnostics. (1) It generates depth scans of samples in a contact-free, nondestructive manner. Having become a standard method for ophthalmologic examinations, (2, 3) within the past decade also applications outside the medical field were found, as summarized in a recent review (4) and with a special focus put on polymer science: in contrast to biological tissues, polymers usually do not contain water and therefore also light in the near-infrared (NIR) region, which otherwise would be absorbed, can be ...

      Read Full Article
    5. Non-destructive evaluation of delamination growth in glass fiber composites using optical coherence tomography

      Non-destructive evaluation of delamination growth in glass fiber composites using optical coherence tomography

      Based on low coherence interferometry, a robust optical coherence tomography (OCT) system has been built. The system was used to monitor the growth of a delamination between the middle layers of a glass fiber composite under a static loading. Firstly specimens of the material used for the spar webs in wind turbines were prepared with an interlaminar crack from free edges. Then they were statically loaded by a customized tensile test stage to extend the delamination length and simultaneously scanned by the OCT system. To process the acquired data, an optimized signal processing algorithm was developed. The cross-sectional images clearly ...

      Read Full Article
    6. Spectroscopic measurement of absorptive thin films by Spectral-Domain Optical Coherence Tomography

      Spectroscopic measurement of absorptive thin films by Spectral-Domain Optical Coherence Tomography

      A non-invasive method for measuring the refractive index, extinction coefficient and film thickness of absorptive thin films using spectral-domain optical coherent tomography is proposed, analyzed and experimentally demonstrated. Such an optical system employing a normal-incident beam of light exhibits a high spatial resolution. There are no mechanical moving parts involved for the measurement except the transversal scanning module for the measurement at various transversal locations. The method was experimentally demonstrated on two absorptive thin-film samples coated on transparent glass substrates. The refractive index and extinction coefficient spectra from 510 to 580 nm wavelength range and film thickness were simultaneously measured ...

      Read Full Article
    7. Cost-effective optical coherence tomography spectrometer based on a tilted fiber Bragg grating

      Cost-effective optical coherence tomography spectrometer based on a tilted fiber Bragg grating

      A compact, fiber-based spectrometer for biomedical application utilizing a tilted fiber Bragg grating (TFBG) as integrated dispersive element is demonstrated. Based on a 45° UV-written PS750 TFBG a refractive spectrometer with 2.06 radiant/μm dispersion and a numerical aperture of 0.1 was set up and tested as integrated detector for an optical coherence tomography (OCT) system. Featuring a 23 mm long active region at the fiber the spectrum is projected via a cylindrical lens for vertical beam collimation and focused by an achromatic doublet onto the detector array. Covering 740 nm to 860 nm the spectrometer was optically ...

      Read Full Article
    8. Optical Coherence Tomography as a Novel Tool for In-Line Monitoring of a Pharmaceutical Film-Coating Process

      Optical Coherence Tomography as a Novel Tool for In-Line Monitoring of a Pharmaceutical Film-Coating Process

      Optical coherence tomography (OCT) is a contact-free non-destructive high-resolution imaging technique based on low-coherence interferometry. This study investigates the application of spectral-domain OCT as an in-line quality control tool for monitoring pharmaceutical film-coated tablets. OCT images of several commercially-available film-coated tablets of different shapes, formulations and coating thicknesses were captured off-line using two OCT systems with centre wavelengths of 830 nm and 1325 nm. Based on the off-line image evaluation, another OCT system operating at a shorter wavelength was selected to study the feasibility of OCT as an in-line monitoring method. Since in spectral-domain OCT motion artefacts can occur as ...

      Read Full Article
    9. Non-Contact Creep Measurement Based on Fourier Domain Optical Coherence Tomography

      Non-Contact Creep Measurement Based on Fourier Domain Optical Coherence Tomography

      A non-contact Fourier-domain optical coherence creep tomography (OCCT) is developed and employed in real-time non-contact creep measurement. Experiments on thermal deformation were carried out by using the self-developed OCCT to measure a high-temperature structure. In the OCCT system, a high-performance spectrometer, and a thermal light are, respectively, employed as the detector and the light source. Due to the broadband of the spectrometer and light source, the system provided high robust performance with an excellent deformation measurement resolution of sub-millimeter scale. Due to the energy leakage effect of FFT, a spectrum correction technique was employed to enhance the resolution of the ...

      Read Full Article
    10. Optical characterization of ultra-short Bragg grating on lithium niobate ridge waveguide

      Optical characterization of ultra-short Bragg grating on lithium niobate ridge waveguide

      In this Letter, we report a technique to etch giant aspect ratio nanostructures in lithium niobate. An 8 μm long Bragg grating on a Ti : LiNbO 3 ridge waveguide was fabricated by combining optical-grade dicing and focused ion beam milling. The reflectivity was evaluated using an optical coherence tomography system: it is measured to be 53% for the TM wave and 47% for the TE wave. We study by 2D-FDTD the modeled behavior of the electromagnetic field when an angle exists between two consecutive sidewalls of the grating in order to understand the difference between ideal Bragg grating and experimental ...

      Read Full Article
    11. Real-time critical dimension measurement of thin film transistor liquid crystal display patterns using optical coherence tomography

      Real-time critical dimension measurement of thin film transistor liquid crystal display patterns using optical coherence tomography

      A coherence scanning tomographic imaging system with an innovative signal correction method is presented for a critical dimension (CD) measurement of thin film transistor liquid crystal display patterns having multiple focus positions within a single field of view. To facilitate the analyzing of coherence signals, a simulation model based on fast Fourier transform method is proposed, and its simulated result is compared with the coherence signals from the actual experiments. The comparison shows that the majority of frequency characteristics from simulation modeling results are matched with the experimental results. However, in many edge regions, discrepancies in frequency characteristics between the ...

      Read Full Article
    12. Optical Coherence Tomography (OCT) for Industrial NDT (Non-Destructive

      Optical Coherence Tomography (OCT) for Industrial NDT (Non-Destructive

      Optical coherence tomography (OCT) has evolved to a non-invasive standard biomedical analysis technique yielding a detail-rich cross-sectional image of living tissue. As a high frequency analog to and as a possible replacement of ultrasound examination techniques, optical coherence tomography delivers images of a much higher resolution well into the micrometer realm. The penetration depth possible with OCT is determined by the type of material under test and the wavelength used as shown in Figure 1. In medical applications, for human tissue investigations, and when using light sources in the short wave infrared, OCT penetration can reach 6mm and more (much ...

      Read Full Article
      Mentions: Xenics
    13. Characterization of PET preforms using spectral domain optical coherence tomography

      Characterization of PET preforms using spectral domain optical coherence tomography

      Polyethylene terephthalate (PET) preforms are massively produced nowadays with the purpose of producing food and beverages packaging and liquid containers. Some varieties of these preforms are produced as multilayer structures, where very thin inner film(s) act as a barrier for nutrients leakage. The knowledge of the thickness of this thin inner layer is important in the production line. The quality control of preforms production requires a fast approach and normally the thickness control is performed by destructive means out of the production line. A spectral domain optical coherence tomography (SD-OCT) method was proposed to examine the thin layers in ...

      Read Full Article
    14. Non-Destructive Evaluation of Polymer Coating Structures on Pharmaceutical Pellets Using Full-Field Optical Coherence Tomography

      Non-Destructive Evaluation of Polymer Coating Structures on Pharmaceutical Pellets Using Full-Field Optical Coherence Tomography

      Full-field optical coherence tomography (FF-OCT) using a conventional light-emitting diode and a complementary metal-oxide semiconductor camera has been developed for characterising coatings on small pellet samples. A set of en-face images covering an area of 700 × 700 μm 2 was taken over a depth range of 166 μm. The three-dimensional structural information, such as the coating thickness and uniformity, was subsequently obtained by analysis of the recorded en-face images. Drug-loaded pharmaceutical sustained-release pellets with two coating layers and of a sub-millimetre diameter were studied to demonstrate the usefulness of the developed system. We have shown that both coatings can be ...

      Read Full Article
    15. One-shot measurement of the air-liquid interface effect by a spectral-domain low-coherence dynamic light scattering technique

      One-shot measurement of the air-liquid interface effect by a spectral-domain low-coherence dynamic light scattering technique

      The Brownian motion of particles close to the interface between air and liquid is investigated using the one-shot measurement of temporal autocorrelation functions as a function of the distance from the interface by using a spectral domain low-coherence dynamic light scattering. The technique is based on the principle of spectral-domain optical coherence tomography combined with that of dynamic light scattering. It is experimentally found that Brownian motion is suppressed in the region close to the air-liquid interface, but increases consistently with distance from the liquid surface, until free Brownian motion occurs. The results confirm the potential of the proposed technique ...

      Read Full Article
    16. Pearl Thickness Measurements from Optical Coherence Tomography Images

      Pearl Thickness Measurements from Optical Coherence Tomography Images

      By measuring the thickness of the nacreous layer, pearl optical coherence tomography (OCT) images are now increasingly used in identification and characterization. An approach to automated thickness measurement of pearl OCT image has been reported in this paper. A Total Variational (TV) Model filter has been used to remove noise in images. After the image filtering, edges are detected by self-adaptive Canny operator. In the end we used circle fitting technologies to archive the goal of automated thickness measurement. The experimental results show this approach is accurate and adaptable.

      Read Full Article
    17. Feature Of The Week 9/8/13: Austrian Researchers Investigate OCT for Analysis of Coatings in Pharmaceutical Tablets

      Feature Of The Week 9/8/13: Austrian Researchers Investigate OCT for Analysis of Coatings in Pharmaceutical Tablets

      Tablet coating is a common pharmaceutical technique to apply a thin continuous layer of solid on the top of a tablet or a granule containing active pharmaceutical ingredients (APIs). The coating itself can serve for different purposes. On the one hand we have the so-called “immediate-release coatings”, which do not have any special effect on the pharmaceutical impact of the tablet, but well on the acceptance among patients and therefore on the commercial success. Examples are increasing the visual attractiveness, taste masking and brand recognition. On the other hand it is possible to apply coatings which actually influence the overall ...

      Read Full Article
    18. Special session dedictated to OCT at the 16th International Conference on Experimental Mechanics - ICEM16, July 2014, Cambridge/UK

      Special session dedictated to OCT at the 16th International Conference on Experimental Mechanics - ICEM16, July 2014, Cambridge/UK

      Special session dedictated to OCT at the 16th International Conference on Experimental Mechanics - ICEM16, 7th to 11th July 2014, Cambridge/UK. The conference brings together internationally leading researchers across a wide range of disciplines in both academia and industry to interchange ideas and discuss new research in the area of experimental mechanics. A special session is dedicated to the application of OCT, which provides access in a non-invasive/non-destructive way to the interior of materials to study their structure and mechanical properties. Contributions for both, biological as well as non-biological applications and case studies, are welcomed as well as dedicated ...

      Read Full Article
      Mentions: David Stifter
    19. Assessment of nanoparticle loading and dispersion in polymeric materials using optical coherence tomography

      Assessment of nanoparticle loading and dispersion in polymeric materials using optical coherence tomography

      The inclusion of small concentrations of nanoparticles can significantly enhance the thermal and electrical properties, and to a lesser degree the mechanical performance, of polymers. Dispersion of nanoparticles during mixing is problematic, with poor mixing resulting in particle agglomeration (i.e. particle clustering), which subsequently limits the potential for property enhancement. Achieving good dispersion is considered key to large-scale production and commercialization of polymer nanocomposites (PNCs), and a measurement technique capable of quantitatively characterizing particle loading and dispersion would significantly enhance product development. This paper presents the results of a study using a static light scattering technique, Fourier domain optical ...

      Read Full Article
    20. VIS-NIR Full-Field Low Coherence Interferometer for Surface Layers Non-destructive Testing and Defects Detection

      VIS-NIR Full-Field Low Coherence Interferometer for Surface Layers Non-destructive Testing and Defects Detection

      Low coherence interferometry (LCI) is a well known measurement technique that allows shape measurements with a nanometer resolution. The range of LCI is theoretically unlimited but in practice it is determined by the length of a scanning motion along the measurement axis. The resolution of the measurement is determined by the scanning resolution, the spectral characteristics of the light source and the fringe analysis algorithm

      Read Full Article
    21. Nondestructive metrology by optical coherence tomography empowering manufacturing iterations of layered polymeric optical materials

      Nondestructive metrology by optical coherence tomography empowering manufacturing iterations of layered polymeric optical materials

      In recent years, there has been an ever-growing interest in exploring different optical materials and components to develop compact and effective optical systems. The design and fabrication of high-performance optics require nondestructive metrology techniques to inspect the samples. We have investigated the capability of optical coherence tomography (OCT) to nondestructively characterize layered polymeric materials. Using a custom developed Gabor-domain optical coherence microscopy system centered at 800 nm with 120 nm full width at half maximum enabling unprecedented 2 μ m resolution both laterally and axially in an 8     mm 3 volume, we investigated the internal structure of 50 μ m thick films ...

      Read Full Article
    22. Kinetics of varnish long-term drying process monitored by a heterogeneous optical sensor system

      Kinetics of varnish long-term drying process monitored by a heterogeneous optical sensor system

      The drying process of an acrylic varnish film was monitored over 24 h by a heterogeneous optical sensor system. The system employs a fibre optic transducer based on Bragg gratings and optical coherence tomography, operating respectively around 1.55 and 1.3 µm. The sensor is able to provide information about the temporal evolution of temperature, mechanical deformation, thickness and average refractive index of the coating during the drying process. Resolutions for these optically measured parameters are 0.05 °C (temperature), 0.5 µε (strain), 1.5 µm (thickness) and 0.004 (refractive index). Besides, the sensor can detect the growth ...

      Read Full Article
    23. Optical coherence tomography as a reference method for the detection of nanoparticles in thin-film polymer matrices

      Optical coherence tomography as a reference method for the detection of nanoparticles in thin-film polymer matrices

      In food and feed production an emerging issue is the use of nanoparticles as additives to control specific properties of the products. In this context, one focus in food chemistry is the development and evaluation of measurement techniques, which could allow the detection and quantification of nanoparticles in food products. For this purpose, special noninvasive and non-destructive reference methods are required, which allow subsequent analysis with other measurement techniques. Additionally, non-invasive and fast imaging techniques are potentially appropriate for applications in the food production. Optical coherence tomography is sensitive to the backscattering of particles and is regarded as a promising ...

      Read Full Article
    24. Optical coherence tomography for non-destructive analysis of coatings in pharmaceutical tablets

      Optical coherence tomography for non-destructive analysis of coatings in pharmaceutical tablets

      Tablet coating is a common pharmaceutical technique to apply a thin continuous layer of solid on the top of a tablet or a granule containing active pharmaceutical ingredients (APIs). Coating thickness and homogeneity are critical parameters regarding the drug release rate, and consequently a direct or indirect monitoring strategy of these critical process parameters is essential. With the aid of Optical Coherence Tomography (OCT) it is not only possible to measure the absolute coating thickness, but also to detect inhomogeneities in the coating or substrate material. In this work the possible application of OCT as in-line method for monitoring pharmaceutical ...

      Read Full Article
    1-24 of 161 1 2 3 4 5 6 7 »
  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, Velocimetry
    4. Miscellaneous:

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

  3. Organizations in the News

    1. (2 articles) Johannes Kepler University of Linz
    2. (1 articles) Delft University of Technology
  4. People in the News

    1. (2 articles) David Stifter
    2. (1 articles) Stefan E. Schausberger
    3. (1 articles) Bettina Heise
    4. (1 articles) Roger M. Groves