1. 1-24 of 101 1 2 3 4 5 »
    1. Supercontinuum generation for ultrahigh-resolution optical coherence tomography at wavelength of 0.8µm using carbon nanotube fiber laser and similariton amplifier

      Supercontinuum generation for ultrahigh-resolution optical coherence tomography at wavelength of 0.8µm using carbon nanotube fiber laser and similariton amplifier

      We demonstrated supercontinuum (SC) generation for ultrahigh-resolution optical coherence tomography (UHR-OCT) in the 0.8 µm wavelength region using an ultrashort-pulse fiber laser system. An Er-doped ultrashort-pulse fiber laser with single-wall carbon nanotubes was developed as the seed pulse source. A 46 fs, highest quality, pedestal-free, clean, ultrashort pulse was generated with a similariton amplifier. Then, a 60 fs ideal ultrashort pulse was generated at a wavelength of 0.8 µm with a second-harmonic generation (SHG) crystal, and a Gaussian-like SC was generated in a photonic crystal fiber. UHR-OCT was demonstrated using the generated SC, and precise images of a ...

      Read Full Article
    2. Anisotropic polyvinyl alcohol hydrogel phantom for shear wave elastography in fibrous biological soft tissue: a multimodality characterization

      Anisotropic polyvinyl alcohol hydrogel phantom for shear wave elastography in fibrous biological soft tissue: a multimodality characterization

      Shear wave elastography imaging techniques provide quantitative measurement of soft tissues elastic properties. Tendons, muscles and cerebral tissues are composed of fibers, which induce a strong anisotropic effect on the mechanical behavior. Currently, these tissues cannot be accurately represented by existing elastography phantoms. Recently, a novel approach for orthotropic hydrogel mimicking soft tissues has been developed (Millon et al 2006 J. Biomed. Mater. Res. B 305–11). The mechanical anisotropy is induced in a polyvinyl alcohol (PVA) cryogel by stretching the physical crosslinks of the polymeric chains while undergoing freeze/thaw cycles. In the present study we propose an original ...

      Read Full Article
    3. Simultaneous estimation of bidirectional particle flow and relative flux using MUSIC-OCT: phantom studies

      Simultaneous estimation of bidirectional particle flow and relative flux using MUSIC-OCT: phantom studies

      In an optical coherence tomography (OCT) scan from a living tissue, red blood cells (RBCs) are the major source of backscattering signal from moving particles within microcirculatory system. Measuring the concentration and velocity of RBC particles allows assessment of RBC flux and flow, respectively, to assess tissue perfusion and oxygen/nutrition exchange rates within micro-structures. In this paper, we propose utilizing spectral estimation techniques to simultaneously quantify bi-directional particle flow and relative flux by spectral estimation of the received OCT signal from moving particles within capillary tubes embedded in tissue mimicking phantoms. The proposed method can be directly utilized for ...

      Read Full Article
    4. Dependence of light attenuation and backscattering on collagen concentration and chondrocyte densityin agarose scaffolds

      Dependence of light attenuation and backscattering on collagen concentration and chondrocyte densityin agarose scaffolds

      Optical coherence tomography (OCT) has been applied for high resolution imaging of articular cartilage. However, the contribution of individual structural elements of cartilage on OCT signal has not been thoroughly studied. We hypothesize that both collagen and chondrocytes, essential structural components of cartilage, act as important light scatterers and that variation in their concentrations can be detected by OCT through changes in backscattering and attenuation. To evaluate this hypothesis, we established a controlled model system using agarose scaffolds embedded with variable collagen concentrations and chondrocyte densities. Using OCT, we measured the backscattering coefficient ( µ b ) and total attenuation coefficient ( µ t ) in ...

      Read Full Article
    5. Influence of different sized nanoparticles combined with ultrasound on the optical properties of invitro normal and cancerous human lung tissue studied with OCT and diffuse reflectance spectra

      Influence of different sized nanoparticles combined with ultrasound on the optical properties of invitro normal and cancerous human lung tissue studied with OCT and diffuse reflectance spectra

      The present study is concerned with the in vitro study of different sized titanium dioxide (TiO 2 ) nanoparticles' (NPs) penetration and accumulation in human normal lung (NL) tissue and lung adenocarcinoma tumor (LAT) tissue by the methods of continuous optical coherence tomography (OCT) monitoring and diffuse reflectance (DR) spectra measurement, and their evaluating the effects of TiO 2 NPs in two sizes (60 nm and 100 nm) and their combination with ultrasound (US) on the optical properties of human NL and LAT tissue. Spectral measurements indicate that TiO 2 NPs penetrate and accumulate into the tissues and thus induce enhancement ...

      Read Full Article
    6. MOEMS optical delay line for optical coherence tomography

      MOEMS optical delay line for optical coherence tomography

      Micro-Opto-Electro-Mechanical optical coherence tomography, a lab-on-chip for biomedical applications is designed, studied, fabricated and characterized. To fabricate the device standard PolyMUMPS processes is adopted. We report the utilization of electro-optic modulator for a fast scanning optical delay line for time domain optical coherence tomography. Design optimization are performed using Tanner EDA while simulations are performed using COMSOL. The paper summarizes various results and fabrication methodology adopted. The success of the device promises a future hand-held or endoscopic optical coherence tomography for biomedical applications.

      Read Full Article
    7. Measurement of the temperature dependence of Young's modulus of cartilage by phase-sensitive optical coherence elastograph

      Measurement of the temperature dependence of Young's modulus of cartilage by phase-sensitive optical coherence elastograph

      The development of an effective system to monitor the changes in the elastic properties of cartilage tissue with increasing temperature in laser reconstruction is an urgent practical task. In this paper, the use of phase-sensitive optical coherence elastography for detection of elastic waves in the sample has allowed Young's modulus of cartilage tissue to be measured directly during heating. Young's modulus was calculated from the group velocity of propagation of elastic waves excited by means of a system supplying focused air pulses. The measurement results are in agreement with the results of measurements of the modulus of elasticity ...

      Read Full Article
    8. Improvement of lateral resolution of spectral domain optical coherence tomography images inout-of-focus regions with holographic data processing techniques

      Improvement of lateral resolution of spectral domain optical coherence tomography images inout-of-focus regions with holographic data processing techniques

      An analogy between spectral-domain optical coherence tomography (SD OCT) data and broadband digital holography data is considered. Based on this analogy, a method for processing SD OCT data, which makes it possible to construct images with a lateral resolution in the whole investigated volume equal to the resolution in the in-focus region, is developed. Several issues concerning practical application of the proposed method are discussed.

      Read Full Article
    9. Volumetric cutaneous microangiography of human skin in vivo by VCSEL swept-source optical coherence tomography

      Volumetric cutaneous microangiography of human skin in vivo by VCSEL swept-source optical coherence tomography

      We demonstrate volumetric cutaneous microangiography of the human skin in vivo that utilises 1.3-μm high-speed sweptsource optical coherence tomography (SS-OCT). The swept source is based on a micro-electro-mechanical (MEMS)-tunable vertical cavity surface emission laser (VCSEL) that is advantageous in terms of long coherence length over 50 mm and 100 nm spectral bandwidth, which enables the visualisation of microstructures within a few mm from the skin surface. We show that the skin microvasculature can be delineated in 3D SS-OCT images using ultrahigh-sensitive optical microangiography (UHS-OMAG) with a correlation mapping mask, providing a contrast enhanced blood perfusion map with ...

      Read Full Article
    10. Multimodal diagnosis and visualisation of oncologic pathologies

      Multimodal diagnosis and visualisation of oncologic pathologies

      The combined application of optical coherence tomography, Raman and autofluorescence spectroscopy of biotissues for the analysis of human malignant neoplasms is demonstrated. Rapid investigation of vast biotissue regions (at the scale of entire organs) is possible using the autofluorescence response. After selection of possible zones of pathologies one can visualise the neoplasm topology in the zone of interest with micron precision by using optical coherence tomography. In the case of suspecting the malignancy the analysis of the biotissue Raman spectrum is carried out that allows identification of the neoplasm type with the sensitivity and specificity ~85%. An experimental scheme is ...

      Read Full Article
    11. Principles and Applications of Fourier Optics (Textbook)

      Principles and Applications of Fourier Optics (Textbook)

      `All of optics is Fourier optics!' While this statement may not be literally true, when there is one basic mathematical tool to explain light propagation and image formation, with both coherent and incoherent light, as well as thousands of practical everyday applications of the fundamentals, Fourier optics is worth studying. This book contains summaries of the principles of Fourier optics that have been developed over the past hundred years and of many applications over the past fifty years, especially since the invention of the laser. This book is intended as a series of guideposts to improve our world through the ...

      Read Full Article
    12. Line-scan Raman microscopy complements optical coherence tomography for tumor boundary detection

      Line-scan Raman microscopy complements optical coherence tomography for tumor boundary detection

      Current technique for tumor resection requires biopsy of the tumor region and histological confirmation before the surgeon can be certain that the entire tumor has been resected. This confirmation process is time consuming both for the surgeon and the patient and also requires sacrifice of healthy tissue, motivating the development of novel technologies which can enable real-time detection of tumor-healthy tissue boundary for faster and more efficient surgeries. In this study, the potential of combining structural information from optical coherence tomography (OCT) and molecular information from line-scan Raman microscopy (LSRM) for such an application is presented. The results show a ...

      Read Full Article
    13. A model for simulating speckle-pattern evolution based on close to reality procedures used inspectral-domain OCT

      A model for simulating speckle-pattern evolution based on close to reality procedures used inspectral-domain OCT

      A robust model for simulating speckle-pattern evolution in optical coherence tomography (OCT) depending on the OCT system parameters and tissue deformation is reported. The model is based on the application of close to reality procedures used in spectral-domain OCT scanners. It naturally generates images reproducing properties of real images in spectral-domain OCT, including the pixelized structure and finite depth of unambiguous imaging, influence of the optical spectrum shape, dependence on the optical wave frequency and coherence length, influence of the tissue straining, etc. Good agreement with generally accepted speckle features and properties of real OCT images is demonstrated.

      Read Full Article
    14. Achromatic registration of quadrature components of the optical spectrum in spectral domain opticalcoherence tomography

      Achromatic registration of quadrature components of the optical spectrum in spectral domain opticalcoherence tomography

      We have thoroughly investigated the method of simultaneous reception of spectral components with the achromatised quadrature phase shift between two portions of a reference wave, designed for the effective suppression of the 'mirror' artefact in the resulting image obtained by means of spectral domain optical coherence tomography (SD OCT). We have developed and experimentally tested a phase-shifting element consisting of a beam divider, which splits the reference optical beam into the two beams, and of delay lines being individual for each beam, which create a mutual phase difference of π/2 in the double pass of the reference beam. The phase ...

      Read Full Article
    15. Nanosensitive optical coherence tomography for the study of changes in static and dynamic structures

      Nanosensitive optical coherence tomography for the study of changes in static and dynamic structures

      We briefly discuss the principle of image formation in Fourier domain optical coherence tomography (OCT). The theory of a new approach to improve dramatically the sensitivity of conventional OCT is described. The approach is based on spectral encoding of spatial frequency. Information about the spatial structure is directly translated from the Fourier domain to the image domain as different wavelengths, without compromising the accuracy. Axial spatial period profiles of the structure are reconstructed for any volume of interest within the 3D OCT image with nanoscale sensitivity. An example of application of the nanoscale OCT to probe the internal structure of ...

      Read Full Article
    16. A method for obtaining scattering decomposed images in optical coherence tomography

      A method for obtaining scattering decomposed images in optical coherence tomography

      A method for obtaining scattering decomposed images in optical coherence tomography based on a multiple scattering model is proposed. Images of different scattering components can be obtained with this method. Employing the proposed method, scattering decomposed images of a biological sample are obtained. Then spatial mean filtering for denoising is performed on only the multiple scattering component, and the total signal is reconstructed. This method is useful for observing the images of different scattering components and has the potential to be applied to information extraction or signal processing on these components separately.

      Read Full Article
    17. Effect of differently sized nanoparticles' accumulation on the optical properties of ex vivo normal and adenomatous human colon tissue with OCT imaging and diffuse reflectance spectra

      Effect of differently sized nanoparticles' accumulation on the optical properties of ex vivo normal and adenomatous human colon tissue with OCT imaging and diffuse reflectance spectra

      Using optical coherence tomography (OCT) and diffuse reflectance spectra, we investigated the dynamics of titanium dioxide (TiO 2 ) nanoparticles, of different sizes, when penetrating and accumulating in human normal colon tissue (NC) and adenomatous colon tissue (AC). The process of nanoparticle penetration and accumulation in biotissue is accompanied by changes in the optical properties of tissue. Continuous OCT monitoring showed that, after application of TiO 2 nanoparticles, the OCT signal intensities of NC and ac both increase with time, and the larger nanoparticles tend to produce a greater signal enhancement in the same type of tissue. The average attenuation coefficient ...

      Read Full Article
    18. Microvascular imaging: techniques and opportunities for clinical physiological measurements

      Microvascular imaging: techniques and opportunities for clinical physiological measurements

      The microvasculature presents a particular challenge in physiological measurement because the vessel structure is spatially inhomogeneous and perfusion can exhibit high variability over time. This review describes, with a clinical focus, the wide variety of methods now available for imaging of the microvasculature and their key applications. Laser Doppler perfusion imaging and laser speckle contrast imaging are established, commercially-available techniques for determining microvascular perfusion, with proven clinical utility for applications such as burn-depth assessment. Nailfold capillaroscopy is also commercially available, with significant published literature that supports its use for detecting microangiopathy secondary to specific connective tissue diseases in patients with ...

      Read Full Article
    19. Measurement of elastic wave propagation velocity near tissue surface by optical coherence tomographyand laser Doppler velocimetry

      Measurement of elastic wave propagation velocity near tissue surface by optical coherence tomographyand laser Doppler velocimetry

      We demonstrate a new technique for measuring the velocity of elastic waves propagating near a tissue surface by swept-source optical coherence tomography (OCT). We establish a theory for estimating the elastic wave velocity from the OCT images taken with a slow mechanical scanning, which is experimentally verified using agar and tissue samples. The elastic wave velocity measured by this technique agrees well with previous results and that measured with a laser Doppler velocimeter. We also carry out some trial measurements of the elastic wave velocities of several tissue samples by this method.

      Read Full Article
    20. Experimental research and observation of the skin response of mice with a second-degree scald duringirradiation by a CO 2 laser

      Experimental research and observation of the skin response of mice with a second-degree scald duringirradiation by a CO 2 laser

      Second-degree scalding is a common dermatological injury. Inappropriate treatment methods in clinical practice always produce scarring, and can lead to skin cancer and other complications in the longer term. In this study optical coherence tomography (OCT) combined with a skin detector was used to monitor the response of second-degree scalded skin tissue irradiated by a CO2 laser. The process of treatment of second-degree scalding was systematically studied from the perspective of tissue optics. The OCT signal intensity was stronger within the whole recovery period in the experimental group undergoing CO2 laser treatment, and the attenuation coefficient (μt) returned ...

      Read Full Article
    21. Two-dimensional optical scanner with monolithically integrated glass microlens

      Two-dimensional optical scanner with monolithically integrated glass microlens

      A miniaturized two-dimensional forward optical scanner with a monolithically integrated glass microlens was developed for microendoscopic imaging applications. The fabricated device measures 2.26 × 1.97 × 0.62 mm 3 in size and a through-silicon microlens with a diameter of 400 µm and numerical aperture of 0.37 has been successfully integrated within the silicon layer. An XY stage structure with lens shuttle and comb actuators was designed, and proprietary glass isolation blocks were utilized in mechanical and electric isolation of X- and Y -axis actuators. Resonant frequencies of the stage in X and Y directions were 3.238 and ...

      Read Full Article
    22. 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
    23. 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
    24. 800-nm-centered swept laser for spectroscopic optical coherence tomography

      800-nm-centered swept laser for spectroscopic optical coherence tomography

      The isosbestic point of oxy- and deoxy-hemoglobin at 800 nm is an important point in biomedical optical spectroscopic imaging. We have developed a novel swept laser centered at 800 nm and demonstrated its performance for spectroscopic optical coherence tomography. The measured −10 dB spectral bandwidth of the swept laser was 40 nm and averaged laser output power per sweep was 4 mW. This swept laser was incorporated into our OCT system and used to measure non-scattering liquid phantoms and blood samples. The measured maximum sensitivity and roll-off rate over a range of image depths were 112 dB and − 1.45 ...

      Read Full Article
    1-24 of 101 1 2 3 4 5 »
  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