1. Articles from Home: SPIE.org

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    1. Towards freehand image acquisition in optical coherence tomography

      Towards freehand image acquisition in optical coherence tomography
      A new data-capture method could provide increased flexibility for clinical imaging applications. Optical coherence tomography (OCT), a biomedical diagnostic-imaging technique, is currently transitioning from the research laboratory into clinical practice.1 Providing micrometer-scale resolution over millimeter-scale fields of view, OCT is the optical analog of ultrasound. It uses low-coherence interferometry to perform optical ranging in biological tissue. Clinical applications under investigation include optical biopsy2 and detection of tumor margins during image-guided surgery.3 The clinical applications of OCT benefit from its real-time imaging capability and diverse sample-arm designs, including hand-held probes, rotating fiber-optic catheters, and miniature needles. The real-time diagnostic ...
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    2. Monitoring oncological surgery using optical coherence tomography

      Monitoring oncological surgery using optical coherence tomography
      Detailed, real-time imaging allows for adjustment of surgical margins, thus sparing healthy tissue and increasing the likelihood of complete tumor removal. Development of local recurrence is one of the main causes of unsatisfactory long-term recovery prospects following cancer surgery. Determining the adequate balance between radical tumor removal and maximum preservation of the surrounding tissue is therefore very important for cancer management and, subsequently, the patient's quality of life. Rates of recurrence following surgical resection are appreciably high for a number of cancers. Following transurethral resection of bladder tumors (TURBT), they are reported to be as high as 40–80 ...
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    3. Optical coherence angiography for the eye

      Optical coherence angiography for the eye
      A new technique for monitoring blood flow will help investigate eye functions and retinal disease. Poor blood supply is one of the main causes of several retinal diseases. Vascular disorders and impaired circulation are observed in major eye diseases that cause blindness, including age-related macular degeneration (AMD)1 and glaucoma.2 A noninvasive, 3D imaging tool for major vascular systems of the eye might be helpful for understanding and diagnosing eye diseases. Circulation abnormalities are typically diagnosed using fluorescence angiography, in which injected fluorescent dye is detected. However, this technique is invasive, may have side effects, and cannot be used ...
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    4. Where is retinal optical coherence tomography heading?

      Where is retinal optical coherence tomography heading?
      Recent advances in imaging technology facilitate cellular-resolution retinal imaging and wide-field 3D visualization, enabling enhanced penetration below the retina for routine diagnosis. Optical coherence tomography (OCT) is a rapidly emerging, noninvasive, optical diagnostic-imaging technique that enables in-vivo cross-sectional visualization of internal microstructure in biological systems at a resolution of a few micrometers.1 Novel high-speed detection techniques and the recent development of tunable light sources with ultrabroad bandwidth have revolutionized imaging performance and the clinical feasibility of OCT. As a consequence, it has become an optical analog to computed tomography and magnetic-resonance imaging. Although OCT does not enable full-body imaging ...
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    5. Multifunctional optical imaging reveals tissue properties of the anterior eye

      Multifunctional optical imaging reveals tissue properties of the anterior eye
      A combination of polarization and Doppler-flow imaging for optical coherence tomography enhances image contrast without sacrificing acquisition speeds. Corneal and anterior-segment optical coherence tomography (CAS-OCT) is an imaging mode used to obtain cross-sectional images of the anterior eye segment in a noncontact and noninvasive manner.1 CAS-OCT has been used in clinics for diagnosis and basic research of ocular diseases such as glaucoma. Although conventional OCT helps to visualize the distribution of backscattering intensities from tissues, unlike histological techniques it does not guarantee clear differentiation of individual tissues. To enhance the contrast of OCT images, the birefringence and Doppler flow ...
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    6. Optical coherence tomography holds promise for conserving art

      Optical coherence tomography holds promise for conserving art
      OCT has migrated successfully from medical imaging to materials science, where it is used online to monitor varnish removal from paintings. Noninvasive examinations of human patients and art objects share more than the important modus operandi of ‘do no harm.’ Soon after medical x-rays were discovered, they were applied to inspect the underlying layers of paintings. More recently, that extended to the newer modality of x-ray tomography. Now, optical coherence tomography (OCT), which acquires and processes optical signals to produce high-quality 3D images, has entered the picture. Medical OCT was first described in 1991,1 and reports of its use ...
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    7. Imaging the Eye: A video interview with Robert Zawadzki

      Imaging the Eye: A video interview with Robert Zawadzki
      Robert J. Zawadzki's research interests focus on the aging human eye. He is working on development of new instrumentation for high-resolution in vivo retina imaging, which allows for visualization of individual cellular structures. This includes optical coherence tomography (OCT) and adaptive optics (AO), scanning laser opthalmoscopy (SLO), and combinations of all three. Adaptive optics can be used to compensate for issues that come up when working with imperfections of the human eye, while OCT
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    8. Cellular imaging of the living human retina

      Cellular imaging of the living human retina
      A device combining optical coherence tomography and adaptive optics can capture micron-scale 3D pictures of the retina. Viewing the retina through the eye's cornea and crystalline lens dates back to the time of Helmholtz, inventor of the ophthalmoscope. Ophthalmoscopes have advanced substantially since then and are now an indispensable non-invasive tool for diagnosis and treatment monitoring. While there are three principal types—conventional ophthalmoscopes, confocal scanning laser ophthalmoscopes (cSLOs), and optical coherence tomography (OCT)).123 The latter has changed the diagnosis and monitoring of retinal and optic nerve disease most.
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    9. High-speed visualization of tissue-perfusion dynamics

      High-speed visualization of tissue-perfusion dynamics
      Optical coherence tomography enhances clinical diagnosis and could increase our understanding of major disease progression. Quantitative knowledge about blood flow in tissues is crucial for evaluating health, and different methods have been applied to assess blood-tissue perfusion, such as Doppler ultrasound and laser-Doppler imaging. Doppler optical coherence tomography (DOCT), a sophisticated non-invasive technique based on optical interferometry which can capture detailed images of biological tissues, provides the best available spatial and temporal resolution to localize and quantify blood flow.1 The first DOCT systems date back to the late 1990s, but the method has yet to find its way into ...
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    10. Optical coherence tomography captures embryonic heart dynamics

      Optical coherence tomography captures embryonic heart dynamics
      An advanced imaging technique has both the spatial and temporal resolution to investigate the developing heart in important animal models such as chicks and mice. In studying the mechanisms that drive early heart formation, researchers rely primarily on static methods such as histology and immunohistochemistry. During cardiac looping, the minuscule heart transforms from a tubular form to a four-chambered heart, a complex process which relies upon mechanical stresses from the functioning heart for feedback. Optical coherence tomography (OCT) imaging emdash a sophisticated, noninvasive technique that can capture detailed images of biological tissue by measuring optical scattering emdash offers the ability ...
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    11. Fourier domain mode locking: new lasers for optical coherence tomography

      Fourier domain mode locking: new lasers for optical coherence tomography
      A new operating regime for rapidly wavelength swept, narrowband light sources has enabled high-performance biomedical imaging. Optical coherence tomography (OCT) generates micron-scale resolution, cross-sectional images of tissue by measuring the echo time delay of backscattered light (see Figure 1).1 Recent work showed that rapidly wavelength-swept narrowband laser sources can be used for this technique.2 This approach, called swept source OCT (ss-OCT), is similar to the frequency modulated radar used in police speed guns, but uses light instead of radio waves. In the technique, one depth scan is generated for each sweep of the laser. The system performance depends ...
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    12. OCT-guided laser therapy shows promise

      OCT-guided laser therapy shows promise
      Advances in optical-coherence tomography may lead to a new class of endoscopic, image-guided therapies that target disease with microscopic precision. Nearly 15 years of technical innovation, robust engineering, and cross-disciplinary collaboration have advanced endoscopic optical-coherence tomography1 (OCT) from a promising laboratory tool to clinically deployed instrumentation. The latest OCT technologies are being studied at research hospitals throughout the world for applications such as heart disease and cancer.2 One of the applications we have pursued in our laboratory is the use of OCT to identify cancer in the gastrointestinal (GI) tract.3,4 It is hoped that OCT's high-resolution ...
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    13. Novel optical-signal acquisition method addresses grand challenges for silicon technology

      Novel optical-signal acquisition method addresses grand challenges for silicon technology
      The superior image definition and nondestructive testing technology provided by optical-coherence tomography targets the characterization issues posed by nanometer-scale devices. The UK's Engineering and Physical Sciences Research Council's recent consultation exercise1 reinforced the belief that future silicon technology will be advanced by new and evolving characterization techniques. Among the grand challenges identified are the development and implementation of nanometer-scale features, 3D structures, and manufacturing quality. The developing market for microelectromechanical systems (MEMS)—which integrate mechanical elements, sensors, actuators, and electronics on a common silicon substrate—provides a proof statement. Driven by the demand for smaller, cheaper, more versatile ...
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    14. Photonic-crystal fiber characteristics benefit numerous applications

      Photonic-crystal fiber characteristics benefit numerous applications
      Advantages in efficiency, beam quality, scalability, and operating cost make new optical fiber technology highly competitive compared to traditional laser designs. Photonic-crystal fibers (PCFs) are among the most specialized optical lightguides. Ranging from fibers with low levels of nonlinearities supporting high-power pulses to highly nonlinear counterparts for supercontinuum generation, PCF is an attractive and versatile technology. It is based on a microstructured arrangement of low- and high-refractive-index materials. The high-index background material is typically undoped silica while the low-index region is usually provided by air holes along the fiber length. They can be made using a stack-and-draw fabrication process (see ...
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      Mentions: NKT Photonics
    15. Photoacoustic microscopy at super depths

      Photoacoustic microscopy at super depths
      Combining light and ultrasound in a single hybrid technology enables multiscale, high-resolution imaging deep into biological tissue. With their ability to sense rich optical contrast in living tissue using harmless nonionizing radiation, commercial high-resolution 3D optical imaging techniques—such as confocal microscopy, two-photon microscopy, and optical coherence tomography—have had a fundamental impact on biomedicine. These techniques, which are collectively known as ballistic imaging, depend on unscattered or minimally scattered photons. Its utility notwithstanding, ballistic imaging also has several limitations. In particular, diffraction constrains its resolution, and because living tissue scatters light, ballistic imaging techniques are unable to penetrate deeper ...
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    16. Effect of paper porosity on OCT images: Monte Carlo study

      Non-invasive measurement of paper porosity is an important problem for papermaking industry. Presently used techniques are invasive and require long time for processing the sample. In recent years optical coherence tomography (OCT) has been proved to be an effective tool for non-invasive study of optically non-uniform scattering media including paper. The aim of present work is to study the potential ability of OCT for sensing the porosity of a paper sample by means of numerical simulations. The paper sample is characterized by variation of porosity along the sample while numerical simulations allow one to consider the samples with constant porosity ...
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    17. Optical imaging of hard and soft dental tissues using discretely swept optical frequency domain reflectometry optical coherence tomography at wavelengths from 1560 to 1600 nm .

      Optical imaging of hard and soft dental tissues using discretely swept optical frequency domain reflectometry optical coherence tomography at wavelengths from 1560 to 1600 nm (Journal Paper) Author(s): Hideo Kakuma; Kohji Ohbayashi; Yasuhiko Arakawa We have been developing a Mach-Zehnder type of optical frequ
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    18. Versatile confocal/optical coherence tomography system for embryonic developmental imaging

      An Optical Coherence Tomography (OCT) imaging system has been designed and constructed to acquire images of scattering biological samples. By simultaneously acquiring and displaying high resolution en-face (C-scan) OCT and Laser Scanning Confocal images of Drosophila melanogaster embryos we demonstrate the potential of the system to be used as a powerful tool for imaging in Drosophila embryonic development. The system can equally be used for non invasive visualizations and measurements of the movement of Drosophila melanogaster larval heart and can easily be switched in the OCT B-scan regime. The confocal channel adds guidance as the specimen can be quickly located ...
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    19. Contribution of various scattering orders to OCT images of skin

      Simulated OCT images of skin were obtained implementing Monte Carlo simulations. The multilayer skin model used in simulations was based on the experimental OCT images obtained at the wavelength of 910 nm. The following skin layers were considered in the model: stratum corneum, epidermis prickle layer, epidermis basal layer, dermis with upper plexus, dermis, and dermis with lower plexus. The images were obtained both with and without speckle accounting. The latter case is calculated from the envelopes of calculated interference signals while the former accounts for the interference fringe patterns. The contributions of least and multiple scattering, diffusive and non-diffusive ...
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    73-96 of 99 « 1 2 3 4 5 »
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