1. 1-24 of 29 1 2 »
    1. Low-Coherence Interferometric Fiber-Optic Sensors with Potential Applications as Biosensors

      Low-Coherence Interferometric Fiber-Optic Sensors with Potential Applications as Biosensors

      Fiber-optic Fabry-Pérot interferometers (FPI) can be applied as optical sensors, and excellent measurement sensitivity can be obtained by fine-tuning the interferometer design. In this work, we evaluate the ability of selected dielectric thin films to optimize the reflectivity of the Fabry-Pérot cavity. The spectral reflectance and transmittance of dielectric films made of titanium dioxide (TiO 2 ) and aluminum oxide (Al 2 O 3 ) with thicknesses from 30 to 220 nm have been evaluated numerically and compared. TiO 2 films were found to be the most promising candidates for the tuning of FPI reflectivity. In order to verify and ...

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    2. Cosmetics, Vol. 4, Pages 2: In Vitro Methodologies to Evaluate the Effects of Hair Care Products on Hair Fiber

      Cosmetics, Vol. 4, Pages 2: In Vitro Methodologies to Evaluate the Effects of Hair Care Products on Hair Fiber

      Consumers use different hair care products to change the physical appearance of their hair, such as shampoos, conditioners, hair dye and hair straighteners. They expect cosmetics products to be available in the market to meet their needs in a broad and effective manner. Evaluating efficacy of hair care products in vitro involves the use of highly accurate equipment. This review aims to discuss in vitro methodologies used to evaluate the effects of hair care products on hair fiber, which can be assessed by various methods, such as Scanning Electron Microscopy, Transmission Electron Microscopy, Atomic Force Microscopy, Optical Coherence Tomography, Infrared ...

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    3. Validating Intravascular Imaging with Serial Optical Coherence Tomography and Confocal Fluorescence Microscopy

      Validating Intravascular Imaging with Serial Optical Coherence Tomography and Confocal Fluorescence Microscopy

      Atherosclerotic cardiovascular diseases are characterized by the formation of a plaque in the arterial wall. Intravascular ultrasound (IVUS) provides high-resolution images allowing delineation of atherosclerotic plaques. When combined with near infrared fluorescence (NIRF), the plaque can also be studied at a molecular level with a large variety of biomarkers. In this work, we present a system enabling automated volumetric histology imaging of excised aortas that can spatially correlate results with combined IVUS/NIRF imaging of lipid-rich atheroma in cholesterol-fed rabbits. Pullbacks in the rabbit aortas were performed with a dual modality IVUS/NIRF catheter developed by our group. Ex vivo ...

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    4. Evaluation of Laser-Assisted Trans-Nail Drug Delivery with Optical Coherence Tomography

      Evaluation of Laser-Assisted Trans-Nail Drug Delivery with Optical Coherence Tomography

      The nail provides a functional protection to the fingertips and surrounding tissue from external injuries. The nail plate consists of three layers including dorsal, intermediate, and ventral layers. The dorsal layer consists of compact, hard keratins, limiting topical drug delivery through the nail. In this study, we investigate the application of fractional CO 2 laser that produces arrays of microthermal ablation zones (MAZs) to facilitate drug delivery in the nails. We utilized optical coherence tomography (OCT) for real-time monitoring of the laser–skin tissue interaction, sparing the patient from an invasive surgical sampling procedure. The time-dependent OCT intensity variance was ...

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    5. Bio-Photonic Detection and Quantitative Evaluation Method for the Progression of Dental Caries Using Optical Frequency-Domain Imaging Method

      Bio-Photonic Detection and Quantitative Evaluation Method for the Progression of Dental Caries Using Optical Frequency-Domain Imaging Method

      The initial detection of dental caries is an essential biomedical requirement to barricade the progression of caries and tooth demineralization. The objective of this study is to introduce an optical frequency-domain imaging technique based quantitative evaluation method to calculate the volume and thickness of enamel residual, and a quantification method was developed to evaluate the total intensity fluctuation in depth direction owing to carious lesions, which can be favorable to identify the progression of dental caries in advance. The cross-sectional images of the ex vivo tooth samples were acquired using 1.3 μm spectral domain optical coherence tomography system (SD-OCT ...

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    6. Full-Field Optical Coherence Tomography Using Galvo Filter-Based Wavelength Swept Laser

      Full-Field Optical Coherence Tomography Using Galvo Filter-Based Wavelength Swept Laser

      We report a wavelength swept laser-based full-field optical coherence tomography for measuring the surfaces and thicknesses of refractive and reflective samples. The system consists of a galvo filter–based wavelength swept laser and a simple Michelson interferometer. Combinations of the reflective and refractive samples are used to demonstrate the performance of the system. By synchronizing the camera with the source, the cross-sectional information of the samples can be seen after each sweep of the swept source. This system can be effective for the thickness measurement of optical thin films as well as for the depth investigation of samples in industrial ...

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    7. Extending the Effective Ranging Depth of Spectral Domain Optical Coherence Tomography by Spatial Frequency Domain Multiplexing

      Extending the Effective Ranging Depth of Spectral Domain Optical Coherence Tomography by Spatial Frequency Domain Multiplexing

      We present a spatial frequency domain multiplexing method for extending the imaging depth range of a spectral domain optical coherence tomography (SDOCT) system without any expensive device. This method uses two galvo scanners with different pivot-offset distances in two independent reference arms for spatial frequency modulation and multiplexing. The spatial frequency contents corresponding to different depth regions of the sample can be shifted to different frequency bands. The spatial frequency domain multiplexing SDOCT system provides an approximately 1.9-fold increase in the effective ranging depth compared with that of a conventional full-range SDOCT system. The reconstructed images of phantom and ...

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    8. Optical Coherence Tomography and Magnetic Resonance Imaging in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder

      Optical Coherence Tomography and Magnetic Resonance Imaging in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder

      Irreversible disability in multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) is largely attributed to neuronal and axonal degeneration, which, along with inflammation, is one of the major pathological hallmarks of these diseases. Optical coherence tomography (OCT) is a non-invasive imaging tool that has been used in MS, NMOSD, and other diseases to quantify damage to the retina, including the ganglion cells and their axons. The fact that these are the only unmyelinated axons within the central nervous system (CNS) renders the afferent visual pathway an ideal model for studying axonal and neuronal degeneration in neurodegenerative diseases. Structural magnetic ...

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    9. Fast Industrial Inspection of Optical Thin Film Using Optical Coherence Tomography

      Fast Industrial Inspection of Optical Thin Film Using Optical Coherence Tomography

      An application of spectral domain optical coherence tomography (SD-OCT) was demonstrated for a fast industrial inspection of an optical thin film panel. An optical thin film sample similar to a liquid crystal display (LCD) panel was examined. Two identical SD-OCT systems were utilized for parallel scanning of a complete sample in half time. Dual OCT inspection heads were utilized for transverse (fast) scanning, while a stable linear motorized translational stage was used for lateral (slow) scanning. The cross-sectional and volumetric images of an optical thin film sample were acquired to detect the defects in glass and other layers that are ...

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    10. Tunable Emission Wavelength Stacked InAs/GaAs Quantum Dots by Chemical Beam Epitaxy for Optical Coherence Tomography

      Tunable Emission Wavelength Stacked InAs/GaAs Quantum Dots by Chemical Beam Epitaxy for Optical Coherence Tomography

      We report on Chemical Beam Epitaxy (CBE) growth of wavelength tunable InAs/GaAs quantum dots (QD) based superluminescent diode’s active layer suitable for Optical Coherence Tomography (OCT). The In-flush technique has been employed to fabricate QD with controllable heights, from 5 nm down to 2 nm, allowing a tunable emission band over 160 nm. The emission wavelength blueshift has been ensured by reducing both dots’ height and composition. A structure containing four vertically stacked height-engineered QDs have been fabricated, showing a room temperature broad emission band centered at 1.1 µm. The buried QD layers remain insensitive to the ...

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    11. An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography

      An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography

      We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT) and optical coherence tomography (OCT). The PAT remotely measures photoacoustic (PA) signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF) and a large-core multimode fiber (MMF). The compact and robust common probe is capable of obtaining both the PA and the OCT ...

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    12. An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography

      An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography

      We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT) and optical coherence tomography (OCT). The PAT remotely measures photoacoustic (PA) signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF) and a large-core multimode fiber (MMF). The compact and robust common probe is capable of obtaining both the PA and the OCT ...

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    13. Enhanced Tissue Ablation Efficiency with a Mid-Infrared Nonlinear Frequency Conversion Laser System and Tissue Interaction Monitoring Using Optical Coherence Tomography

      Enhanced Tissue Ablation Efficiency with a Mid-Infrared Nonlinear Frequency Conversion Laser System and Tissue Interaction Monitoring Using Optical Coherence Tomography

      We report development of optical parametric oscillator (OPO)-based mid-infrared laser system that utilizes a periodically poled nonlinear crystal pumped by a near-infrared (NIR) laser. We obtained a mid-infrared average output of 8 W at an injection current of 20 A from a quasi-phase-matched OPO using an external cavity configuration. Laser tissue ablation efficiency is substantially affected by several parameters, including an optical fluence rate, wavelength of the laser source, and the optical properties of target tissue. Dimensions of wavelength and radiant exposure dependent tissue ablation are quantified using Fourier domain optical coherence tomography and the ablation efficiency was compared ...

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      Mentions: Dae Yu Kim
    14. Comparing Macular Thickness Measurements in Patients with Diabetic Macular Edema with the Optos Spectral OCT/SLO and Heidelberg Spectralis HRA + OC

      Comparing Macular Thickness Measurements in Patients with Diabetic Macular Edema with the Optos Spectral OCT/SLO and Heidelberg Spectralis HRA + OC

      The aim of this study was to compare measurements of macular thickness, obtained from patients with diabetic macular edema, using two spectral-domain optical coherence tomography (SD-OCT) devices. These were the Spectralis Heidelberg Retina Angiograph + Optical Coherence Tomography (HRA + OCT) (Heidelberg Engineering), which is often considered the gold-standard for OCT measurement, and the Spectral Optical Coherence Tomography/Scanning Laser Ophthalmoscopy (OCT/SLO) (Optos plc), which can additionally perform microperimetry, a useful measure of visual function. In this prospective observational study, each eye had SD-OCT performed with both devices on the same day by the same investigator. Mean retinal thickness was calculated ...

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    15. Effect of Outflow Tract Banding on Embryonic Cardiac Hemodynamics

      Effect of Outflow Tract Banding on Embryonic Cardiac Hemodynamics

      We analyzed heart wall motion and blood flow dynamics in chicken embryos using in vivo optical coherence tomography (OCT) imaging and computational fluid dynamics (CFD) embryo-specific modeling. We focused on the heart outflow tract (OFT) region of day 3 embryos, and compared normal (control) conditions to conditions after performing an OFT banding intervention, which alters hemodynamics in the embryonic heart and vasculature. We found that hemodynamics and cardiac wall motion in the OFT are affected by banding in ways that might not be intuitive a priori . In addition to the expected increase in ventricular blood pressure, and increase blood flow ...

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    16. New Trends in Dental Biomechanics with Photonics Technologies

      New Trends in Dental Biomechanics with Photonics Technologies

      Engineering techniques used to evaluate strain-stress fields, materials’ mechanical properties, and load transfer mechanisms, among others, are useful tools in the study of biomechanical applications. These engineering tools, as experimental and numerical ones, were imported to biomechanics, in particular in dental biomechanics, a few decades ago. Several experimental techniques have been used in dental biomechanics, like photoelasticity, ESPI (Electronic Speckle Pattern Interferometry), strain gages, and other kinds of transducers. However, these techniques have some limitations. For instance, photoelasticity and ESPI give the overall field pattern of the strain, showing the stress-strain concentration points. These methods cannot give an accurate measurement ...

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    17. Wide-Field OCT Angiography at 400 kHz Utilizing Spectral Splitting

      Wide-Field OCT Angiography at 400 kHz Utilizing Spectral Splitting

      Optical angiography systems based on optical coherence tomography (OCT) require dense sampling in order to maintain good vascular contrast. We demonstrate a way to gain acquisition speed and spatial sampling by using spectral splitting with a swept source OCT system. This method splits the recorded spectra into two to several subspectra. Using continuous lateral scanning, the lateral sampling is then increased by the same factor. This allows increasing the field of view of OCT angiography, while keeping the same transverse resolution and measurement time. The performance of our method is demonstrated in vivo at different locations of the human retina ...

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    18. Fiber-Based Polarization Diversity Detection for Polarization-Sensitive Optical Coherence Tomography

      Fiber-Based Polarization Diversity Detection for  Polarization-Sensitive Optical Coherence Tomography

      We present a new fiber-based polarization diversity detection (PDD) scheme for polarization sensitive optical coherence tomography (PSOCT). This implementation uses a new custom miniaturized polarization-maintaining fiber coupler with single mode (SM) fiber inputs and polarization maintaining (PM) fiber outputs. The SM fiber inputs obviate matching the optical lengths of the two orthogonal OCT polarization channels prior to interference while the PM fiber outputs ensure defined orthogonal axes after interference. Advantages of this detection scheme over those with bulk optics PDD include lower cost, easier miniaturization, and more relaxed alignment and handling issues. We incorporate this PDD scheme into a galvanometer-scanned ...

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    19. Preliminary Design and Evaluation of a B-Scan OCT-Guided Needle

      Preliminary Design and Evaluation of a B-Scan OCT-Guided Needle

      Real-time intraoperative B-scan optical coherence tomography (OCT) visualization of intraocular tissues is a desired ophthalmic feature during retinal procedures. A novel intraocular 25-gauge B-mode forward-imaging OCT probe was combined with a 36-gauge needle into a prototype instrument. Imaging of the needle tip itself and the effects of saline injection into a gelatin phantom were performed. A combined B-scan forward-imaging OCT-needle prototype was capable of real-time-imaging of saline injection into a gelatin phantom. Additional future miniaturization may permit this instrument to be an adjunctive real-time imaging and procedure tool for vitreoretinal surgery.

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    20. A Fiber Bragg Grating Sensor Interrogation System Based on a Linearly Wavelength-Swept Thermo-Optic Laser Chip

      A Fiber Bragg Grating Sensor Interrogation System Based on a Linearly Wavelength-Swept Thermo-Optic Laser Chip

      A linearized wavelength-swept thermo-optic laser chip was applied to demonstrate a fiber Bragg grating (FBG) sensor interrogation system. A broad tuning range of 11.8 nm was periodically obtained from the laser chip for a sweep rate of 16 Hz. To measure the linear time response of the reflection signal from the FBG sensor, a programmed driving signal was directly applied to the wavelength-swept laser chip. The linear wavelength response of the applied strain was clearly extracted with an R-squared value of 0.99994. To test the feasibility of the system for dynamic measurements, the dynamic strain was successfully interrogated ...

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    21. Two-Level Optical Coherence Tomography Scheme for Suppressing Spectral Saturation Artifacts

      Two-Level Optical Coherence Tomography Scheme for Suppressing Spectral Saturation Artifacts

      We demonstrate a novel method for reducing saturation artifacts in spectral-domain optical coherence tomography (SD-OCT) systems. This method is based on a two-level SD-OCT system with a dual-line charge-coupled device (CCD) camera. We compensate the saturated signal detected by the first line using the unsaturated signal detected by the second line. The Fourier transform of the compensated spectrum shows effective suppression of saturation artifacts. This method was also successfully performed on phantom material and skin on a human finger. Our method causes neither back-scattering power loss nor signal-to-noise ratio (SNR) degradation. The only difference between the traditional system and our ...

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    22. Endoscopic Optical Coherence Tomography for Clinical Gastroenterology

      Endoscopic Optical Coherence Tomography for Clinical Gastroenterology

      Optical coherence tomography (OCT) is a real-time optical imaging technique that is similar in principle to ultrasonography, but employs light instead of sound waves and allows depth-resolved images with near-microscopic resolution. Endoscopic OCT allows the evaluation of broad-field and subsurface areas and can be used ancillary to standard endoscopy, narrow band imaging, chromoendoscopy, magnification endoscopy, and confocal endomicroscopy. This review article will provide an overview of the clinical utility of endoscopic OCT in the gastrointestinal tract and of recent achievements using state-of-the-art endoscopic 3D-OCT imaging systems.

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    23. Development of Real-Time Dual-Display Handheld and Bench-Top Hybrid-Mode SD-OCTs

      Development of Real-Time Dual-Display Handheld and Bench-Top Hybrid-Mode SD-OCTs

      Development of a dual-display handheld optical coherence tomography (OCT) system for retina and optic-nerve-head diagnosis beyond the volunteer motion constraints is reported. The developed system is portable and easily movable, containing the compact portable OCT system that includes the handheld probe and computer. Eye posterior chambers were diagnosed using the handheld probe, and the probe could be fixed to the bench-top cradle depending on the volunteers’ physical condition. The images obtained using this handheld probe were displayed in real time on the computer monitor and on a small secondary built-in monitor; the displayed images were saved using the handheld probe ...

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    24. Dental Optical Coherence Tomography

      Dental Optical Coherence Tomography

      This review paper describes the applications of dental optical coherence tomography (OCT) in oral tissue images, caries, periodontal disease and oral cancer. The background of OCT, including basic theory, system setup, light sources, spatial resolution and system limitations, is provided. The comparisons between OCT and other clinical oral diagnostic methods are also discussed.

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    1-24 of 29 1 2 »
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