1. 1-24 of 572 1 2 3 4 ... 22 23 24 »
    1. Rat brain imaging using full field optical coherence microscopy with short multimode fiber probe

      Rat brain imaging using full field optical coherence microscopy with short multimode fiber probe

      We demonstrated FF OCM(full field optical coherence microscopy) using an ultrathin forward-imaging SMMF (short multimode fiber) probe of 50 μm core diameter, 125 μm diameter, and 7.4 mm length, which is a typical graded-index multimode fiber for optical communications. The axial resolution was measured to be 2.20 μm, which is close to the calculated axial resolution of 2.06 μm. The lateral resolution was evaluated to be 4.38 μm using a test pattern. Assuming that the FWHM of the contrast is the DOF (depth of focus), the DOF of the signal is obtained at 36 μm ...

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    2. High frame-rate en face optical coherence tomography system using KTN optical beam deflector

      High frame-rate en face optical coherence tomography system using KTN optical beam deflector

      We developed high frame-rate en face optical coherence tomography (OCT) system using KTa 1-x Nb x O 3 (KTN) optical beam deflector. In the imaging system, the fast scanning was performed at 200 kHz by the KTN optical beam deflector, while the slow scanning was performed at 800 Hz by the galvanometer mirror. As a preliminary experiment, we succeeded in obtaining en face OCT images of human fingerprint with a frame rate of 800 fps. This is the highest frame-rate obtained using time-domain (TD) en face OCT imaging. The 3D-OCT image of sweat gland was also obtained by our imaging ...

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    3. Speckle variance optical coherence tomography using an SS-OCT system and an extended k-sampling clock

      Speckle variance optical coherence tomography using an SS-OCT system and an extended k-sampling clock

      is vacant or filled with material having a refractive index different from the tissue, the observed structure is deformed significantly. This deformation artifact can be minimized by filling the cavity with liquid having a refractive index nearly equal to the tissue. Furthermore, by using dynamical OCT method, cavity image intensity can be significantly enhanced compared with the tissue. This image contrast improvement may allow imaging of cavity structures inside deep in tissues. In this paper, we demonstrate good contrast of speckle variance OCT imaging of phantoms. A trial of deep OCT imaging is introduced with which we can extend the ...

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    4. Master/slave: the ideal tool for coherence revival based optical coherence tomography imaging instruments

      Master/slave: the ideal tool for coherence revival based optical coherence tomography imaging instruments

      In this communication, we present the utility of the Master/Slave (MS) method in combination with the coherence revival technique to obtain full axial range Optical Coherence Tomography (OCT) cross-section images. The MS method eliminates two major drawbacks of the conventional Fourier Transformed (FT) based OCT technology when applied to the coherence revival technique: the need of data re-sampling as well as the need to compensate for unbalanced dispersion in the interferometer.

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    5. Ultralong-range optical coherence tomography-based angiography by akinetic swept source

      Ultralong-range optical coherence tomography-based angiography by akinetic swept source

      Most of current OCT-based angiography suffers from small FOV with short imaging range. Here we implement an ultralong-range OCT system for vascular imaging based on an akinetic swept source. This swept-source OCT (SS-OCT) system enables us to achieve up to 46 mm long imaging range with unprecedented roll-off performance. To compare with traditional spectral domain OCT (SD-OCT) system, we demonstrated the vascular imaging of the entire mice brain with wide FOV by this ultralong-range SS-OCT system and captured the blood flow images at different depth position, which shows the great advantages and bright future of this ultralong-range SS-OCT in vascular ...

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    6. Dual-beam angular compounding for speckle reduction in optical coherence tomography

      Dual-beam angular compounding for speckle reduction in optical coherence tomography

      Optical coherence tomography (OCT), as a low-coherence interferometric imaging technique, inevitably suffers from speckle noise, which can reduce image quality and signal-to-noise (SNR). In this paper, we present a dual-beam angular compounding method to reduce speckle noise and improve SNR of OCT image. Two separated parallel light beams are created on the sample arm using a 1x2 optical fiber coupler and are focused into samples at different angles. The epi-detection scheme creates three different light path combinations of these two light beams above. The three combinations produce three images in single B-scan, which are completely separated in depth. The three ...

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    7. Textural analysis of optical coherence tomography skin images: quantitative differentiation between healthy and cancerous tissues

      Textural analysis of optical coherence tomography skin images: quantitative differentiation between healthy and cancerous tissues

      Optical Coherence Tomography (OCT) offers real-time high-resolution three-dimensional images of tissue microstructures. In this study, we used OCT skin images acquired from ten volunteers, neither of whom had any skin conditions addressing the features of their anatomic location. OCT segmented images are analyzed based on their optical properties (attenuation coefficient) and textural image features e.g., contrast, correlation, homogeneity, energy, entropy, etc. Utilizing the information and referring to their clinical insight, we aim to make a comprehensive computational model for the healthy skin. The derived parameters represent the OCT microstructural morphology and might provide biological information for generating an atlas ...

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    8. High sensitivity contrast enhanced optical coherence tomography for functional in vivo imaging

      High sensitivity contrast enhanced optical coherence tomography for functional in vivo imaging

      In this study, we developed and applied highly-scattering large gold nanorods (LGNRs) and custom spectral detection algorithms for high sensitivity contrast-enhanced optical coherence tomography (OCT). We were able to detect LGNRs at a concentration as low as 50 pM in blood. We used this approach for noninvasive 3D imaging of blood vessels deep in solid tumors in living mice. Additionally, we demonstrated multiplexed imaging of spectrally-distinct LGNRs that enabled observations of functional drainage in lymphatic networks. This method, which we call MOZART, provides a platform for molecular imaging and characterization of tissue noninvasively at cellular resolution

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    9. Gold nanoparticles evaluation using functional optical coherence tomography

      Gold nanoparticles evaluation using functional optical coherence tomography

      The main object of this research was to assess the ability to characterize the gold nanoparticles using optical modalities like optical coherence tomography. Since the nanoparticles, especially gold one, have been very attractive for medical diagnosis and treatment the amount of research activities have been growing rapidly. The nanoparticles designed for different applications like contrast agents or drugs delivery change the optical features of tissue in different way. Therefore, the expanded analysis of scattering optical signal may lead to obtain much more useful information about the tissues health and the treatment efficiency. The noninvasive measurements of the concentration and distribution ...

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    10. High contrast and polarization-artifact-free optical coherence tomography by maximum a-posteriori estimation

      High contrast and polarization-artifact-free optical coherence tomography by maximum a-posteriori estimation

      We propose a maximum a-posteriori (MAP) intensity estimator to improve the image contrast of polarization diversity (PD)-OCT imaging to achieve high contrast polarization-artifact-free images. The MAP estimator compensates for the inevitable reduction of signal-to-noise ratio (SNR) in PD-OCT caused by the splitting of power into two polarization detection channels. It also has low noise-offset in low intensity regions such as the vitreous. This method is applied to posterior eye images, and shows high-contrast, polarization-artifact-free images. This method also enables attenuation coefficient imaging with finer differentiation of attenuation levels.

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    11. Multimodal swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography at 400 kHz

      Multimodal swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography at 400 kHz

      Multimodal imaging systems that combine scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) have demonstrated the utility of concurrent en face and volumetric imaging for aiming, eye tracking, bulk motion compensation, mosaicking, and contrast enhancement. However, this additional functionality trades off with increased system complexity and cost because both SLO and OCT generally require dedicated light sources, galvanometer scanners, relay and imaging optics, detectors, and control and digitization electronics. We previously demonstrated multimodal ophthalmic imaging using swept-source spectrally encoded SLO and OCT (SS-SESLO-OCT). Here, we present system enhancements and a new optical design that increase our SS-SESLO-OCT data throughput ...

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    12. Classification of human ovarian tissue using full field optical coherence tomography

      Classification of human ovarian tissue using full field optical coherence tomography

      The feasibility of a full-field optical coherence tomography (FFOCT) system for rapid wide field optical analysis of normal and malignant human ovarian tissue pathologies was demonstrated. Five features were extracted from the normalized image histogram from 56 FFOCT images, based on the differences in the morphology of the normal and malignant tissue samples.

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    13. Non-contact rapid optical coherence elastography by high-speed 4D imaging of elastic waves

      Non-contact rapid optical coherence elastography by high-speed 4D imaging of elastic waves

      Shear wave OCE (SW-OCE) uses an OCT system to track propagating mechanical waves, providing the information needed to map the elasticity of the target sample. In this study we demonstrate high speed, 4D imaging to capture transient mechanical wave propagation. Using a high-speed Fourier domain mode-locked (FDML) swept-source OCT (SS-OCT) system operating at ~1.62 MHz A-line rate, the equivalent volume rate of mechanical wave imaging is 16 kvps (kilo-volumes per second), and total imaging time for a 6 x 6 x 3 mm volume is only 0.32 s. With a displacement sensitivity of ~10 nanometers, the proposed 4D ...

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    14. Design and optimization of a miniaturized imaging probe for simultaneous endomicroscopy and optical coherence tomography

      Design and optimization of a miniaturized imaging probe for simultaneous endomicroscopy and optical coherence tomography

      A highly-integrated MEMS-based bimodal probe design with integrated piezoelectric fiber scanner for simultaneous endomicroscopy and optical coherence tomography (OCT) is presented. The two modalities rely on spectrally-separated optical paths that run partially in parallel through a micro-optical bench system, which has dimensions of only 13 x 2 x 3mm 3 (l x w x h). An integrated tubular piezoelectric fiber scanner is used to perform en face scanning required for three dimensional OCT measurements. This scanning engine has an outer diameter of 0.9mm and a length of 9mm, and features custom fabricated 10 μm thick polyimide flexible interconnect lines ...

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    15. Correlation between polarization sensitive optical coherence tomography and SHG microscopy in articular cartilage

      Correlation between polarization sensitive optical coherence tomography and SHG microscopy in articular cartilage

      Polarization-sensitive optical coherence tomography (PS-OCT) and second harmonic generation (SHG) microscopy are two imaging modalities with different resolutions, field-of-views (FOV), and contrasts, while they both have the capability of imaging collagen fibers in biological tissues. PS-OCT can measure the tissue birefringence which is induced by highly organized fibers while SHG can image the collagen fiber organization with high resolution. Articular cartilage, with abundant structural collagen fibers, is a suitable sample to study the correlation between PS-OCT and SHG microscopy. Qualitative conjecture has been made that the phase retardation measured by PS-OCT is affected by the relationship between the collagen fiber ...

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    16. Multi-volumetric registration and mosaicking using swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography

      Multi-volumetric registration and mosaicking using swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography

      Ophthalmic diagnostic imaging using optical coherence tomography (OCT) is limited by bulk eye motions and a fundamental trade-off between field-of-view (FOV) and sampling density. Here, we introduced a novel multi-volumetric registration and mosaicking method using our previously described multimodal swept-source spectrally encoded scanning laser ophthalmoscopy and OCT (SS-SESLO-OCT) system. Our SS-SESLO-OCT acquires an entire en face fundus SESLO image simultaneously with every OCT cross-section at 200 frames-per-second. In vivo human retinal imaging was performed in a healthy volunteer, and three volumetric datasets were acquired with the volunteer moving freely and refixating between each acquisition. In post-processing, SESLO frames were used ...

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    17. Dependence on fiber Fabry-Pérot tunable filter characteristics in an all-fiber swept-wavelength laser for use in an optical coherence tomography system

      Dependence on fiber Fabry-Pérot tunable filter characteristics in an all-fiber swept-wavelength laser for use in an optical coherence tomography system

      Optical coherence tomography (OCT) has become a useful and common diagnostic tool within the field of ophthalmology. Although presently a commercial technology, research continues in improving image quality and applying the imaging method to other tissue types. Swept-wavelength lasers based upon fiber ring cavities containing fiber Fabry-P´erot tunable filters (FFP-TF), as an intracavity element, provide swept-source optical coherence tomography (SS-OCT) systems with a robust and scalable platform. The FFP-TF can be fabricated within a large range of operating wavelengths, free spectral ranges (FSR), and finesses. To date, FFP-TFs have been fabricated at operating wavelengths from 400 nm to 2 ...

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      Mentions: Micron Optics
    18. Scattering angle resolved optical coherence tomography for in vivo murine retinal imaging

      Scattering angle resolved optical coherence tomography for in vivo murine retinal imaging

      Optical coherence tomography (OCT) retinal imaging contributes to understanding central nervous system (CNS) diseases because the eye is an anatomical “window to the brain” with direct optical access to nonmylenated retinal ganglion cells. However, many CNS diseases are associated with neuronal changes beyond the resolution of standard OCT retinal imaging systems. Though studies have shown the utility of scattering angle resolved (SAR) OCT for particle sizing and detecting disease states ex vivo, a compact SAR-OCT system for in vivo rodent retinal imaging has not previously been reported. We report a fiber-based SAR-OCT system (swept source at 1310 nm ± 65 nm ...

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    19. In vivo monitoring laser tissue interaction using high resolution Fourier-domain optical coherence tomography

      In vivo monitoring laser tissue interaction using high resolution Fourier-domain optical coherence tomography

      Laser-induced therapies include laser ablation to remove or cut target tissue by irradiating high-power focused laser beam. These laser treatments are widely used tools for minimally invasive surgery and retinal surgical procedures in clinical settings. In this study, we demonstrate laser tissue interaction images of various sample tissues using high resolution Fourier-domain optical coherence tomography (Fd-OCT). We use a Q-switch diode-pumped Nd:YVO4 nanosecond laser (532nm central wavelength) with a 4W maximum output power at a 20 kHz repetition rate to ablate in vitro and in vivo samples including chicken breast and mouse ear tissues. The Fd-OCT system acquires time-series ...

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      Mentions: Dae Yu Kim
    20. Extracting relevant information for cancer diagnosis from dynamic full field OCT through image processing and learning

      Extracting relevant information for cancer diagnosis from dynamic full field OCT through image processing and learning

      For a large number of cancer surgeries, the lack of reliable intraoperative diagnosis leads to reoperations or bad outcomes for the patients. To deliver better diagnosis, we developed Dynamic Full Field OCT (D-FFOCT) as a complement to FFOCT. FFOCT already presents interesting results for cancer diagnosis e.g. Mohs surgery and reaching 96% accuracy on prostate cancer. D-FFOCT accesses the dynamic processes of metabolism and gives new tools to diagnose the state of a tissue at the cellular level to complement FFOCT contrast. We developed a processing framework that intends to maximize the information provided by the FFOCT technology as ...

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    21. Retinal imaging with adaptive optics full-field OCT

      Retinal imaging with adaptive optics full-field OCT

      Adaptive optics full-filed OCT (FFOCT) with a transmissive liquid crystal spatial light modulator (LCSLM) as wavefront corrector is used without strict plane conjugation for low order aberrations corrections. We validated experimentally that FFOCT resolution is independent of aberrations and only reduce the signal level. A signal based sensorless algorithm was thus applied for wavefront distortion compensation. Image quality improvements by the wavefront sensorless control of the LCSLM were evaluated on in vitro samples. By replacing the FFOCT sample arm objective with an artificial eye used to train ophthalmologists, adaptive optics retinal imaging was achieved. In vivo experiments using a liquid ...

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    22. Image-guided feedback for ophthalmic microsurgery using multimodal intraoperative swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography

      Image-guided feedback for ophthalmic microsurgery using multimodal intraoperative swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography

      Surgical interventions for ocular diseases involve manipulations of semi-transparent structures in the eye, but limited visualization of these tissue layers remains a critical barrier to developing novel surgical techniques and improving clinical outcomes. We addressed limitations in image-guided ophthalmic microsurgery by using microscope-integrated multimodal intraoperative swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography (iSS-SESLO-OCT). We previously demonstrated in vivo human ophthalmic imaging using SS-SESLO-OCT, which enabled simultaneous acquisition of en face SESLO images with every OCT cross-section. Here, we integrated our new 400 kHz iSS-SESLO-OCT, which used a buffered Axsun 1060 nm swept-source, with a surgical microscope and ...

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    23. Multi-beam optical coherence tomography for microvascular imaging of human skin in vivo

      Multi-beam optical coherence tomography for microvascular imaging of human skin in vivo

      In this paper, a multi-beam optical coherence tomography (OCT) was used to reconstruct the microvascular image of human skin in vivo with phase resolved Doppler OCT (PRDOCT), phase resolved Doppler variance (PRDV) and speckle variance OCT (svOCT), in which the blood flow image was calculated by averaging the four blood flow images obtained by the four beams. In PRDOCT method, it is difficult to detect the blood flow perpendicular to optical axis of the probe beam for single beam OCT, but the multi-beam scanning method can solve this because the input angles of the four probe beams are slightly different ...

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    24. Birefringence and vascular imaging of in vivo human skin by Jones-matrix optical coherence tomography

      Birefringence and vascular imaging of in vivo human skin by Jones-matrix optical coherence tomography

      A customized 1310-nm Jones-matrix optical coherence tomography (JM-OCT) for dermatological investigation was constructed and used for in vivo normal human skin tissue imaging. This system can simultaneously measure the threedimensional depth-resolved local birefringence, complex-correlation based OCT angiography (OCT-A), degree-ofpolarization- uniformity (DOPU) and scattering OCT intensity. By obtaining these optical properties of tissue, the morphology, vasculature, and collagen content of skin can be deduced and visualized. Structures in the deep layers of the epithelium were observed with depth-resolved local birefringence and polarization uniformity images. These results suggest high diagnostic and investigative potential of JM-OCT for dermatology.

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