1. Articles in category: NDE/NDT

    1-24 of 460 1 2 3 4 ... 18 19 20 »
    1. Image processing based detection of the fibre orientation during depth-controlled laser ablation of CFRP monitored by optical coherence tomography

      Image processing based detection of the fibre orientation during depth-controlled laser ablation of CFRP monitored by optical coherence tomography

      Layer-accurate and precisely stepped removal of damaged areas is required for the repairing process of parts made of carbon fibre-reinforced plastic (CFRP) to obtain a high bonding strength of the repair plies in the rebuilding process. Conventional techniques are characterized by a high degree of manual labour and mechanical load of the processed part. Here, a novel laser-based and controlled approach for automated and layer-accurate removal of damaged areas is presented. In-line depth measurements by optical coherence tomography during nanosecond laser ablation enable depth-controlled homogeneous material removal with minimum damage <10 μm and low surface roughness in the range of ...

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    2. Inpainting for Saturation Artifacts in Optical Coherence Tomography using Dictionary-based Sparse Representation

      Inpainting for Saturation Artifacts in Optical Coherence Tomography using Dictionary-based Sparse Representation

      Saturation artifacts in optical coherence tomography (OCT) occur when received signal exceeds the dynamic range of spectrometer. Saturation artifact shows a streaking pattern and could impact the quality of OCT images, leading to inaccurate medical diagnosis. In this paper, we automatically localize saturation artifacts and propose an artifact correction method via inpainting. We adopt a dictionary-based sparse representation scheme for inpainting. Experimental results demonstrate that, in both case of synthetic artifacts and real artifacts, our method outperforms interpolation method and Euler's elastica method in both qualitative and quantitative results. The generic dictionary offers similar image quality when applied to ...

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    3. Study on cocoonase, sericin, and degumming of silk cocoon: computational and experimental

      Study on cocoonase, sericin, and degumming of silk cocoon: computational and experimental

      Cocoonase is a proteolytic enzyme that helps in dissolving the silk cocoon shell and exit of silk moth. Chemicals like anhydrous Na2CO3, Marseille soap, soda, ethylene diamine and tartaric acid-based degumming of silk cocoon shell have been in practice. During this process, solubility of sericin protein increased resulting in the release of sericin from the fibroin protein of the silk. However, this process diminishes natural color and softness of the silk. Cocoonase enzyme digests the sericin protein of silk at the anterior portion of the cocoon without disturbing the silk fibroin. However, no thorough characterization of cocoonase ...

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      Mentions: UCSF
    4. Material-specific imaging of nanolayers using extreme ultraviolet coherence tomography

      Material-specific imaging of nanolayers using extreme ultraviolet coherence tomography

      Scientific and technological progress depend substantially on the ability to image on the nanoscale. In order to investigate complex, functional, nanoscopic structures like, e.g., semiconductor devices, multilayer optics, or stacks of 2D materials, the imaging techniques not only have to provide images but should also provide quantitative information. We report the material-specific characterization of nanoscopic buried structures with extreme ultraviolet coherence tomography. The method is demonstrated at a laser-driven broadband extreme ultraviolet radiation source, based on high-harmonic generation. We show that, besides nanoscopic axial resolution, the spectral reflectivity of all layers in a sample can be obtained using algorithmic ...

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    5. Recent progress of nondestructive techniques for fruits damage inspection: a review

      Recent progress of nondestructive techniques for fruits damage inspection: a review

      In the process of growing, harvesting, and storage, fruits are vulnerable to mechanical damage , microbial infections, and other types of damage , which not only reduce the quality of fruits , increase the risk of fungal infections, in turn greatly affect food safety, but also sharply reduce economic benefits. Hence, it is essential to identify damaged fruits in time. Rapid and nondestructive detection of fruits damage is in great demand. In this paper, the latest research progresses on the detection of fruits damage by nondestructive techniques , including visible/near-infrared spectroscopy, chlorophyll fluorescence techniques , computer vision, multispectral and hyperspectral imaging, structured-illumination reflectance imaging ...

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    6. Forensic Problems, Optical Solutions

      Forensic Problems, Optical Solutions

      Since first hitting the scene in 1991, optical coherence tomography (OCT) has become a leviathan among biomedical imaging techniques, due to the method’s nondestructive ability to resolve layers of tissue. In ophthalmology, especially, OCT has been revolutionary, imaging retinal layers noninvasively through an approximately one-inch-thick watery window—the human eye. Now, U.K. researchers in applied optics, forensic science and the document-examination industry have joined forces to apply OCT to the high-resolution subsurface analysis of multilayered identification documents (Sci. Justice, doi: 10.1016/j.scijus.2020.12.001 ). The method can reportedly detect forged passports or national ID cards ...

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    7. Media filter fouling assessment using optical coherence tomography: New methodolog

      Media filter fouling assessment using optical coherence tomography: New methodolog

      Drip irrigation is an efficient and safe system for reusing wastewater in agriculture. Since emitter clogging is its main limitation, filtration is needed for preventing it. Media filters are commonly used when irrigation water has a high particle load. However, particle removal through a media bed in media filters used in drip irrigation systems has not been widely studied mainly due to experimental difficulties. To overcome this issue a new methodology using optical coherence tomography (OCT) is presented here. Experiments were carried out on a media filter at laboratory scale using wastewater. Once the filter was clogged, several 20 mm ...

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    8. Sub-surface imaging technology can expose counterfeit travel documents

      Sub-surface imaging technology can expose counterfeit travel documents

      ew research by the University of Kent has found that optical coherence tomography (OCT) imaging technology can be utilised to distinguish between legitimate and counterfeit travel documents. OCT imaging has been widely used in the medical and biomedical fields, recognised as transforming the field of clinical ophthalmology, and this research published in Science & Justice has now identified its capabilities for forgery detection use. This was a joint study between the Applied Optics Group (PDRA Dr Manuel Marques and Professor Adrian Podoleanu) and the Forensic Group (Reader Robert Green OBE) in the University of Kent's School of Physical Sciences, while ...

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    9. A new method for measuring pen pressure in forensic handwriting analysis – a proof of concept study

      A new method for measuring pen pressure in forensic handwriting analysis – a proof of concept study

      This work describes a new method for the analysis of handwritten documents through a system composed of a pre-selector optical analyser equipped with light sources of different wavelengths coupled with bandpass filters combined with an optical coherence tomography (OCT) instrument. The optical analyser identifies regions with different pen pressures on the paper using specific wavelengths from ultraviolet (UV) to infrared (IR) and bandpass filters. Then the selected regions are analysed with a coherence tomography analyser to measure the depth of grooves and capture three-dimensional images. With this methodology, it is possible to identify similarities, or differences, between the pieces of ...

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    10. Towards real time assessment of intramuscular fat content in meat using optical fiber-based optical coherence tomography

      Towards real time assessment of intramuscular fat content in meat using optical fiber-based optical coherence tomography

      We consider the use of optical coherence tomography (OCT) imaging to predict the quality of meat. We find that intramuscular fat (IMF) absorbs infrared light about nine times stronger than muscle, which enables us to estimate fat content in intact meat samples. The method is made very efficient by extracting relevant information from the three-dimensional high-resolution images generated by OCT using principal component analysis (PCA). The principal components are then used as regressors into a support vector regression (SVR) prediction model. The SVR model is found to predict IMF content stably and accurately, with an R 2 value of 0 ...

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    11. Contactless mapping of ceramic green density using optical coherence tomography

      Contactless mapping of ceramic green density using optical coherence tomography

      We propose a contactless method for mapping the density distribution of green ceramics using optical coherence tomography (OCT). A correlation was found between the OCT signal and density of green alumina tablets. Using this relationship, proof-of-concept mapping of model samples produced reasonable results, suggesting that high-speed, contactless mapping of the ceramic green density with micrometer-scale resolution is possible, owing to the unique features of OCT. This technique may contribute to more efficient and eco-friendly ceramics production.

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    12. Mechano-Vibrational Spectroscopy of Tissues and Materials Using Vibrational Optical Coherence Tomography: A New Non-Invasive and Non-Destructive Technique

      Mechano-Vibrational Spectroscopy of Tissues and Materials Using Vibrational Optical Coherence Tomography: A New Non-Invasive and Non-Destructive Technique

      Elastic moduli of tissues andsynthetic polymeric materials are important design properties needed to develop new implants. In this paper we report the use of vibrational optical coherence tomography (VOCT) to measure the resonant frequency and calculate the modulus of tissues and synthetic polymers non-invasively and non-destructively in vitro and in vivo . Values of tissue and polymer moduli were obtained by applying an audible sinusoidal sound wave to the surface of each specimen. The sound wave travels to the interior of the material and is reflected back to the surface from underlying layers. A spectrum of resonant frequencies and moduli are ...

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    13. Identification of Organs Inside Hard Tick Body Using Spectral-domain Optical Coherence Tomography

      Identification of Organs Inside Hard Tick Body Using Spectral-domain Optical Coherence Tomography

      Ixodidae tick, also known as a hard tick, is one of the major vectors of various tick-borne diseases. Studying its anatomy is the fundamental approach for diverse acarological studies and the key to understanding tick morphology. However, the conventional methods of observing internal organs rely primarily on dissection, which damages specimens irrecoverably. In this study, we developed an optical coherence tomography (OCT) system to non-invasively investigate the morphological characteristics of the hard tick. Herein, OCT imaging was conducted by the developed spectral-domain OCT (SD-OCT) system with two different objective lenses. The developed system provides an axial resolution (in the air ...

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    14. Initial Study for the Determination of the Sequence of Intersecting Lines between Gel Pens and Seals by Optical Coherence Tomography

      Initial Study for the Determination of the Sequence of Intersecting Lines between Gel Pens and Seals by Optical Coherence Tomography

      Determining the sequence of intersecting lines is a significant issue in the forensic document examination that can reveal the fraud or distinguish between different allegations. Optical coherence tomography (OCT) is a high-resolution cross-sectional imaging technique that has been introduced into forensic science field recently. The potential of OCT as a novel method to determine the sequence of intersecting lines was examined for the first time. In this study, a spectral-domain OCT system with a center wavelength of 900 nm was employed to perform nondestructive examination on determining the sequence of 18 heterogeneous intersecting line samples produced using three types of ...

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    15. Integrated System for Combined Optical Coherence Tomography-Raman Spectroscopy of Neocaridina denticulate sinensis

      Integrated System for Combined Optical Coherence Tomography-Raman Spectroscopy of Neocaridina denticulate sinensis

      Optical coherence tomography (OCT) and Raman spectroscopy (RS) can be complementary biological tissue optical analysis methods. To study the internal structure and tissue compositions of biological samples, an OCT-RS system was built to carry out OCT section imaging and RS analysis in common. Neocaridina denticulate sinensis were collected regularly for morphological observation by OCT imaging and biochemical investigation based on the Raman spectra. The internal structure of the N. denticulate sinensis was imaged by OCT, and the morphology of the tissues and the position in the body were distinguished according to the gray scale changes. The imaging depth along the ...

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    16. Applying optical coherence tomography for weld depth monitoring in remote laser welding of automotive battery tab connectors

      Applying optical coherence tomography for weld depth monitoring in remote laser welding of automotive battery tab connectors

      This paper addresses in-process monitoring of weld penetration depth (WPD) during remote laser welding of battery tab connectors using optical coherence tomography (OCT). The research aims at studying the impact of welding process parameters on the accuracy of WPD measurements. In general, the highest measurement accuracy is achievable by positioning the OCT measuring beam toward the bottom of the keyhole. However, finding and maintaining the alignment between the OCT measuring beam and the bottom of the keyhole is a challenging task because of the dynamic changes in the size and shape of the keyhole itself. The paper addresses the above ...

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    17. Analyzing Scaling Behavior of Calcium Sulfate in Membrane Distillation via Optical Coherence Tomography

      Analyzing Scaling Behavior of Calcium Sulfate in Membrane Distillation via Optical Coherence Tomography

      Deepening the understanding of scaling processes would facilitate the improvement of membrane distillation (MD) as a promising technique for sustainable development. This study investigated the scaling of calcium sulfate in MD via an approach based on optical coherence tomography (OCT). The OCT-based characterization enabled an analysis that correlated the flux decline with the morphological evolution of the scaling layer. It was revealed by this analysis that the reduction in the evaporation rate could be dominated by different mechanisms as the crystalline particles grew and deposited on the membrane surface; the striping phenomenon visualized by mapping the local growth rates provided ...

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    18. Photonics for Forensics: new publication on peer-reviewed journal

      Photonics for Forensics: new publication on peer-reviewed journal

      A study on the applicability of optical coherence tomography imaging for questioned documents examination, particularly identification documents (national ID cards and passports) has just been published by researchers from the Applied Optics group, the Forensic Science Research group in our School, and Foster and Freeman, Ltd., a manufacturer of forensic science lab equipment. This is a unique study for the group and the wider school, where Photonics was so exquisitely used for Forensic Science research. It is also another step in our work together with Foster and Freeman, which should hopefully enable even more fruitful collaboration in the future. This ...

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    19. Sub-surface characterisation of latest-generation identification documents using optical coherence tomography

      Sub-surface characterisation of latest-generation identification documents using optical coherence tomography

      The identification of individuals, particularly at international border crossings, coupled with the evolving sophistication of identity documents are issues that authorities must contend with. Particularly, the ability to distinguish legitimate from counterfeit documents, with high throughput, sensitivity, and selectivity is an ever-evolving challenge. Over the last decade, an increasing number of security features have been introduced by authorities in identification documents. The latest generation of travel documents (such as passports and national ID cards) forego paper substrates for several layers of polycarbonate, allowing security features to be embedded within the documents. These security features may contain information at either the ...

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    20. Microfluidic organ-on-a-chip model of the outer blood–retinal barrier with clinically relevant read-outs for tissue permeability and vascular structure

      Microfluidic organ-on-a-chip model of the outer blood–retinal barrier with clinically relevant read-outs for tissue permeability and vascular structure

      The outer blood–retinal barrier (oBRB) tightly controls the transport processes between the neural tissue of the retina and the underlying blood vessel network. The barrier is formed by the retinal pigment epithelium (RPE), its basal membrane and the underlying choroidal capillary bed. Realistic three-dimensional cell culture based models of the oBRB are needed to study mechanisms and potential treatments of visual disorders such as age-related macular degeneration that result from dysfunction of the barrier tissue. Ideally, such models should also include clinically relevant read-outs to enable translation of experimental findings in the context of pathophysiology. Here, we report a ...

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    21. Real-time monitoring of pharmaceutical coatings by optical coherence tomography (OCT)

      Real-time monitoring of pharmaceutical coatings by optical coherence tomography (OCT)

      heir dissolution profile and stability are affected by the thickness and homogeneity of the coating layer(s), for example, and their appearance depends on the roughness of the coating film. For drug products with a tailored dissolution behaviour, it is crucial to reach the specified thickness of the coating layer exactly. Traditional testing is based on sampling a handful tablets from the coating drum and manually measuring either diameter or weight gain. These methods are statistically not representative and are influenced by both the operator and tablet core variation. Information in terms of coating quality is missing and the off-line ...

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    22. Researchers demonstrate nondestructive mid-infrared imaging using entangled photons

      Researchers demonstrate nondestructive mid-infrared imaging using entangled photons

      Researchers have shown that entangled photons can be used to improve the penetration depth of optical coherence tomography (OCT) in highly scattering materials. The method represents a way to perform OCT with mid-infrared wavelengths and could be useful for non-destructive testing and analysis of materials such as ceramics and paint samples.

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      Mentions: RECENDT
    23. PhD position in the Applied Optics Group, University of Kent, Canterbury UK

      PhD position in the Applied Optics Group, University of Kent, Canterbury UK

      Project Summary Plant cuticle and underlying epidermis forms the outermost layer protecting plants from desiccation and from abiotic and biotic stresses. The cuticle comprises mainly of polyester cutin and epicuticular waxes that help to prevent moisture loss and maintenance of cell turgor. In fruits changes in surface properties play an important role in increasing consumer appeal during maturation through development of ‘blooms’ and colour changes. Importantly, the cuticle and epidermis form a mechanical barrier acting as the first-line in defence against the ingress from plant pathogens. The PhD Studentship will aim to develop optical coherence tomography (a non-invasive high-resolution microscopy ...

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    24. Effects of the chlorination and pressure flushing of drippers fed by reclaimed wastewater on biofouling

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

      Milli-channel baffle labyrinths are widely used in drip irrigation systems. They induce a pressure drop enabling drip irrigation. However, with a section thickness that is measured in mm 2 , they are sensitive to clogging, which 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 ...

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    1-24 of 460 1 2 3 4 ... 18 19 20 »
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