1. Articles in category: Other Non-Medical

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    1. Accurate velocity measurements of boundary-layer flows using Doppler optical coherence tomography

      Accurate velocity measurements of boundary-layer flows using Doppler optical coherence tomography

      Pulsed ultrasound Doppler velocimetry and nuclear magnetic resonance imaging are popular non-invasive measurement methods for flows of opaque fluids. The spatial and temporal resolution of these methods, however, is quite limited, and they lack accuracy, especially close to solid boundaries. In this paper, we show that solution to these problems is achieved by using Doppler optical coherence tomography (DOCT). DOCT provides simultaneous information about the fluid structure and velocity with very high spatial and temporal resolution. For benchmarking of the method we use water as the reference fluid. We show how DOCT gives a very good agreement with theory for ...

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    2. Internal fingerprint acquisition from optical coherence tomography fingertip scans

      Internal fingerprint acquisition from optical coherence tomography fingertip scans

      Current surface fingerprint scanners measure the surface topography of skin, resulting in vulnerabilities to surface skin erosion, distortion due to contact with the scanner, and fingerprint counterfeiting. An improved means of fingerprint acquisition is necessitated in these facts. By employing an imaging technique known as Optical Coherence Tomography to the human fingertip skin, a three-dimensional digital reconstruction of subsurface layers of skin can be used for the extraction of an internal fingerprint. The internal fingerprint is robust towards counterfeiting, damage, and distortion, thus providing a replacement for the surface fingerprint. However, OCT scans are corrupted by speckle noise and have ...

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    3. Internal fingerprint zone detection in optical coherence tomography fingertip scans

      Internal fingerprint zone detection in optical coherence tomography fingertip scans

      Optical coherence tomography (OCT) is a high-resolution imaging technology capable of capturing a three-dimensional (3-D) representation of fingertip skin. The papillary junction—a junction layer of skin containing the same topographical features as the surface fingerprint—is contained within this representation. The top edge of the papillary junction contains the topographical information pertinent to the internal fingerprint. Extracting the internal fingerprint from OCT fingertip scans has been shown to be possible. Currently, acquiring the internal fingerprint involves manually defining the region containing it. This manner of definition is inefficient. Perfect knowledge of the location of the papillary junction is hypothesized ...

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    4. Six-dimensional Optical Multilayer Storage Using Two-photon Absorption Writing, Erasing and Optical Coherence Tomography Reading

      Six-dimensional Optical Multilayer Storage Using Two-photon Absorption Writing, Erasing and Optical Coherence Tomography Reading

      This invention relates a method of six-dimensional optical multilayer storage using two-photon absorption writing, erasing and optical coherence tomography reading and the apparatus designed based on this method. The invented system stores data in three spatial dimensions plus three physical dimensions of wavelength, intensity and polarization.

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    5. Visualization of dynamic boiling processes using high-speed optical coherence tomography

      Visualization of dynamic boiling processes using high-speed optical coherence tomography

      Investigating microscale nucleate boiling processes with high heat flux requires experimental visualization and quantification with high spatial resolution in the micrometer range as well as a sufficient temporal resolution. Numerous measurement techniques are employed for providing comprehensive experimental data on microscale boiling processes and other multiphase flows. In this context, optical coherence tomography (OCT) has been introduced recently for the visualization of quasistatic growing vapor bubbles in turbid fluids with a high spatial resolution. Since OCT detects backscattered light, only one optical access is necessary and OCT is feasible for measurements in turbid media, where other imaging techniques fail. Within ...

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    6. A review of state-of-the-art speckle reduction techniques for optical coherence tomography fingertip scans

      A review of state-of-the-art speckle reduction techniques for optical coherence tomography fingertip scans

      Standard surface fingerprint scanners are vulnerable to counterfeiting attacks and also failure due to skin damage and distortion. Thus a high security and damage resistant means of fingerprint acquisition is needed, providing scope for new approaches and technologies. Optical Coherence Tomography (OCT) is a high resolution imaging technology that can be used to image the human fingertip and allow for the extraction of a subsurface fingerprint. Being robust toward spoofing and damage, the subsurface fingerprint is an attractive solution. However, the nature of the OCT scanning process induces speckle: a correlative and multiplicative noise. Six speckle reducing filters for the ...

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    7. Tomographic Inspection of Fiber Coils Using Optical Coherence Tomography

      Tomographic Inspection of Fiber Coils Using Optical Coherence Tomography

      We report the first study of using optical coherence tomography (OCT) to inspect the winding quality of fiber optical gyro coils. We use a swept-source OCT system to scan a quadrupole-wind fiber coil for obtaining its two-dimensional and three-dimensional (3D) tomographic images. The defects beneath the surface of the fiber coil, which otherwise are invisible by video inspection, can be clearly identified with such tomographic images. The winding quality of each layer can also be independently visualized with the reconstructed 3D images from different angles or in different sections. We believe that the proposed method will be useful to ensuring ...

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    8. Extracting subsurface fingerprints using Optical Coherence Tomography

      Extracting subsurface fingerprints using Optical Coherence Tomography

      Physiologists have found that fingerprint patterns exist in the inner layers (viz. papillary junction) of the skin of the fingertip. However, conventional acquisition systems do not have capabilities to extract fingerprints at subsurface layers of the finger for use in identity authentication. The subsurface fingerprint representation is of a higher quality than the surface representation as it does not contain deformations such as creases or scars which may be present on the surface of the fingertip. This paper presents a novel approach to extract the subsurface fingerprint representation using a high-resolution imaging technology known as Optical Coherence Tomography (OCT).

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    9. Gravity-driven membrane filtration as pretreatment for seawater reverse osmosis: Linking biofouling layer morphology with flux stabilization

      Gravity-driven membrane filtration as pretreatment for seawater reverse osmosis: Linking biofouling layer morphology with flux stabilization

      In this study gravity-driven membrane (GDM) ultrafiltration is investigated for the pretreatment of seawater before reverse osmosis (RO). The impacts of temperature (21 ± 1 and 29 ± 1 °C) and hydrostatic pressure (40 and 100 mbar) on dynamic flux development and biofouling layer structure were studied. The data suggested pore constriction fouling was predominant at the early stage of filtration, during which the hydrostatic pressure and temperature had negligible effects on permeate flux. With extended filtration time, cake layer fouling played a major role, during which higher hydrostatic pressure and temperature improved permeate flux. The permeate flux stabilized in a range ...

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    10. Method and device for early non-invasive diagnosis of fruit tree disease

      Method and device for early non-invasive diagnosis of fruit tree disease

      The present invention relates to a non-invasive early diagnostic method and device that allows an early diagnosis of Marssonina blotch disease, which infects apple tree leaves, before the occurrence of lesions to enable early prevention of apple Marssonina blotch disease. The method and device of the present invention comprise the following steps: irradiating a broadband light source on an apple tree leaf undergoing diagnosis by means of optical coherence tomography; detecting interference signals from light reflected from the apple tree leaf undergoing diagnosis and light reflected from a reference arm; signal processing the interference signals, which have been detected through ...

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    11. A Novel Approach to Characterizing the Growth of a Fouling Layer during Membrane Filtration via Optical Coherence Tomography

      A Novel Approach to Characterizing the Growth of a Fouling Layer during Membrane Filtration via Optical Coherence Tomography

      Fouling control is one of the critical issues in membrane filtration and plays a very important role in water/wastewater treatment. Better understanding of the underlying fouling mechanisms entails novel characterization techniques that can realize a real-time non-invasive observation and provide high resolution images recording the formation of a fouling layer . This work presents a characterization method based on optical coherence tomography (OCT), which is able to detect the internal structures and motions by analyzing the interference signals. An OCT system was incorporated with a lab-scale membrane filtration system, and the growth of the fouling layer was observed by using ...

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    12. The Application of Optical Coherence Tomography to Image Subsurface Tissue Structure of Antarctic Krill Euphausia superba

      The Application of Optical Coherence Tomography to Image Subsurface Tissue Structure of Antarctic Krill Euphausia superba

      Many small open ocean animals, such as Antarctic krill, are an important part of marine ecosystems. To discover what will happen to animals such as krill in a changing ocean, experiments are run in aquaria where conditions can be controlled to simulate water characteristics predicted to occur in the future. The response of individual animals to changing water conditions can be hard to observe, and with current observation techniques it is very difficult to follow the progress of an individual animal through its life. Optical coherence tomography (OCT) is an optical imaging technique that allows images at high resolution to ...

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    13. Optical coherence tomography for shape and radius of curvature measurements of deeply curved machined metallic surfaces: a comparison with two-beam laser interferometry

      Optical coherence tomography for shape and radius of curvature measurements of deeply curved machined metallic surfaces: a comparison with two-beam laser interferometry

      An application of optical coherence tomography (OCT) for measuring shape and the radius of curvature of deeply curved metallic surfaces in precision mechanical components is demonstrated. Measurements carried out by OCT technique on concave and convex hemispherical metallic surfaces generated by diamond turning process is presented. The technique is compared with a two-beam laser interferometric method for determinations of shape errors and radius of curvature. It is shown that OCT is a useful tool for three-dimensional shape determinations for deeply curved surfaces such as hemispheres and has advantages over two-beam laser interferometric method.

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      Mentions: K. Divakar Rao
    14. Michelson Diagnostics launches new improved version of VivoSight OCT scanner with Micro-Camera to aid skin cancer diagnosis

      Michelson Diagnostics launches new improved version of VivoSight OCT scanner with Micro-Camera to aid skin cancer diagnosis

      Michelson Diagnostics, the UK based medical device company focused on multi-beam Optical Coherence Tomography (‘OCT’) technology, announces the launch of a new improved version of its innovative VivoSight OCT scanner at the European Academy of Dermatology and Venereology (EADV) Annual Meeting, 8-12 October, Amsterdam. The VivoSight scanner probe is now equipped with a new Micro Camera that provides the user with a real-time, colour, magnified view of the skin lesion being scanned. The new Micro Camera image is shown simultaneously with the vertical and en face OCT images, making the VivoSight scanner the only dermatological clinical OCT device to provide ...

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    15. Extreme optical confinement in a slotted photonic crystal waveguide

      Extreme optical confinement in a slotted photonic crystal waveguide

      Using Optical Coherence Tomography, we measure the attenuation of slow light modes in slotted photonic crystal waveguides. When the group index is close to 20, the attenuation is below 300 dB cm −1 . Here, the optical confinement in the empty slot is very strong, corresponding to an ultra-small effective cross section of 0.02  μ m 2 . This is nearly 10 times below the diffraction limit at λ  = 1.5  μ m, and it enables an effective interaction with a very small volume of functionalized matter.

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    16. Feature Of The Week 9/21/14: National University of Singapore Investigates OCT as a Tool for Characterization of Complex Biological Surfaces Including Morphology of Crab Shells

      Feature Of The Week 9/21/14: National University of Singapore Investigates OCT as a Tool for Characterization of Complex Biological Surfaces Including Morphology of Crab Shells

      The advent of scanning electron microscopy has facilitated our understanding of the In recent years, there has been a growing interest in the study of natural biological surfaces in the search for novel solutions in surface engineering design from nature. Most methods for surface imaging of natural biological samples are however, sacrificial and require that samples be sectioned and prepared for characterization. One example is the use of the scanning electron microscope (SEM) to obtain detailed images of microtopography, where a section of the specimen is cut and sputter coated with electrically conductive material like gold or platinum for scanning ...

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    17. 3D Polymer Weld Seam Characterization Based on Optical Coherence Tomography for Laser Transmission Welding Applications

      3D Polymer Weld Seam Characterization Based on Optical Coherence Tomography for Laser Transmission Welding Applications

      Laser transmission welding is an established single-stage plastic joining process, which enables hermetically sealed joints under the workpiece surface. The process requires joining partners with proper degrees of transmission and absorption to the processing wavelength. For reaching a stable process an in-process quality assurance is very valuable. Current monitoring systems have a limited usage, as no quantitative information of the weld itself is obtained without its destruction. In medical and pharmaceutical applications a weld with leakage is e.g. unacceptable. The main objective of this paper is the presentation of the optical coherence tomography as a tool for the quality ...

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    18. Surface imaging of metallic material fractures using optical coherence tomography

      Surface imaging of metallic material fractures using optical coherence tomography

      We demonstrate the capability of optical coherence tomography (OCT) to perform topography of metallic surfaces after being subjected to ductile or brittle fracturing. Two steel samples, OL 37 and OL 52, and an antifriction Sn–Sb–Cu alloy were analyzed. Using an in-house-built swept source OCT system, height profiles were generated for the surfaces of the two samples. Based on such profiles, it can be concluded that the first two samples were subjected to ductile fracture, while the third one was subjected to brittle fracture. The OCT potential for assessing the surface state of materials after fracture was evaluated by ...

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    19. Using Optical Coherence Tomography to Examine Additives in Chinese Song Jun Glaze

      Using Optical Coherence Tomography to Examine Additives in Chinese Song Jun Glaze

      We use optical coherence tomography (OCT) to acquire microstructure images of Chinese Song Jun glaze to reveal the copper and quartz additives used and, in two typical samples, we show that the amount added is considerable. Focusing on these two additives, including the species, amount and granule (particle) size added in the glaze, the objective of the present study is to explore how they functioned in relation to the Jun glaze's visual characteristics, opalescence and sky-blue colour, attributed to the unique liquid–liquid phase separation that occurs in Jun glaze.

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    20. En-face full-field optical coherence tomography for fast and efficient fingerprints acquisition

      En-face full-field optical coherence tomography for fast and efficient fingerprints acquisition

      Optical coherence tomography (OCT) has been recently proposed by a number of laboratories as a promising tool for fingerprints acquisitions and for fakes discrimination. Indeed OCT being a non-contact, non-destructive optical method that virtually sections the volume of biological tissues that strongly scatter light it appears obvious to use it for fingerprints. Nevertheless most of the OCT setups have to go through the long acquisition of a full 3D image to isolate an “en-face” image suitable for fingerprint analysis. A few “en-face” OCT approaches have been proposed that use either a complex 2D scanning setup and image processing, or a ...

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    21. Improved inspection and micrometrology of embedded structures in multi-layered ceramics: Development of optical coherence tomographic methods and tools (Thesis)

      Improved inspection and micrometrology of embedded structures in multi-layered ceramics: Development of optical coherence tomographic methods and tools (Thesis)

      Roll-to-roll manufacturing of micro components based on advanced printing, structuring and lamination of ceramic tapes is rapidly progressing. This large-scale and cost-effective manufacturing process of ceramic micro devices is however prone to hide defects within the visually opaque tape stacks. To achieve a sustainable manufacturing with zero defects in the future, there is an urgent need for reliable inspection systems. The systems to be developed have to perform high-resolution in-process quality control at high speed. Optical coherence tomography (OCT) is a promising technology for detailed in-depth inspection and metrology. Combined with infrared screening of larger areas it can solve the ...

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    22. Growth Kinetics of Concave Nanocubes Studied by Optical Coherence Tomography

      Growth Kinetics of Concave Nanocubes Studied by Optical Coherence Tomography

      This work presents the analysis of the growth kinetics of two syntheses of concave gold nanocubes with a mean size of 72 and 108 nm followed by the optical coherence tomography (OCT) technique by acquiring B-scan images each 5 s. In addition, ultra violet-visible (UV-Vis) spectra and mean size from dynamic light scattering (DLS) were acquired during nanoparticle growth to generate kinetic plots in order to corroborate the OCT results. Kinetic plots from OCT images were obtained by plotting contrast enhancement of B-scan images as function of time. Fitting parameters values given by using the classical Kolmogorov-Johnson-Mehl-Avrami (KJMA) equation show ...

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    23. 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 ...

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