1. Articles from sheng-lung huang

    1-24 of 33 1 2 »
    1. Ultra-broadband wavelength-swept Ti:sapphire crystal fiber laser

      Ultra-broadband wavelength-swept Ti:sapphire crystal fiber laser

      An ultra-broadband wavelength-swept laser (WSL) was generated using glass-clad Ti:sapphire crystal fiber as the gain media. Due to the low signal propagation loss of the crystal fiber, the swept laser has a tuning bandwidth of 250 nm (i.e., 683 nm to 933 nm) at a repetition rate of 1200 Hz. The steady-state and pulsed dynamics of the WSL were analyzed. The 0.018-nm instantaneous linewidth corresponds to a 3-dB coherence roll-off of 7 mm. When using the laser for swept-source optical coherence tomography, an estimated axial resolution of 1.8 µm can be achieved.

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    2. Depth-dependent in vivo human skin backscattering spectra extraction from full-field optical coherence tomography

      Depth-dependent in vivo human skin backscattering spectra extraction from full-field optical coherence tomography

      With homemade active crystalline fibers, we generated bright and broadband light sources for full-field optical coherence tomography, offering deep penetration into skin tissues with cellular resolution at a high frame rate. Extraction of backscattered spectra from the tissue has potential applications in biomedicine. The hysteresis nonlinearity of the piezoelectric transducer actuating the Mirau interferometer has been greatly reduced by a by a feedforward compensation approach. The linearized hysteresis response enables us to extract depth-dependent spectra accurately. To validate, the complex dispersion of a fused silica plate was characterized with 2% error. Further validation on an in vitro setting, the backscattered ...

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    3. Classification of squamous cell carcinoma from FF-OCT images: Data selection and progressive model construction

      Classification of squamous cell carcinoma from FF-OCT images: Data selection and progressive model construction

      We investigate the speed and performance of squamous cell carcinoma (SCC) classification from full-field optical coherence tomography (FF-OCT) images based on the convolutional neural network (CNN). Due to the unique characteristics of SCC features, the high variety of CNN, and the high volume of our 3D FF-OCT dataset, progressive model construction is a time-consuming process. To address the issue, we develop a training strategy for data selection that makes model training 16 times faster by exploiting the dependency between images and the knowledge of SCC feature distribution. The speedup makes progressive model construction computationally feasible. Our approach further refines the ...

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    4. Generation of Augmented Capillary Network Optical Coherence Tomography Image Data of Human Skin for Deep Learning and Capillary Segmentation

      Generation of Augmented Capillary Network Optical Coherence Tomography Image Data of Human Skin for Deep Learning and Capillary Segmentation

      The segmentation of capillaries in human skin in full-field optical coherence tomography (FF-OCT) images plays a vital role in clinical applications. Recent advances in deep learning techniques have demonstrated a state-of-the-art level of accuracy for the task of automatic medical image segmentation. However, a gigantic amount of annotated data is required for the successful training of deep learning models, which demands a great deal of effort and is costly. To overcome this fundamental problem, an automatic simulation algorithm to generate OCT-like skin image data with augmented capillary networks (ACNs) in a three-dimensional volume (which we called the ACN data) is ...

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    5. Submicron spatial resolution optical coherence tomography for visualising the 3D structures of cells cultivated in complex culture systems

      Submicron spatial resolution optical coherence tomography for visualising the 3D structures of cells cultivated in complex culture systems

      Three-dimensional (3D) configuration of in vitro cultivated cells has been recognised as a valuable tool in developing stem cell and cancer cell therapy. However, currently available imaging approaches for live cells have drawbacks, including unsatisfactory resolution, lack of cross-sectional and 3D images, and poor penetration of multi-layered cell products, especially when cells are cultivated on semitransparent carriers. Herein, we report a prototype of a full-field optical coherence tomography (FF-OCT) system with isotropic submicron spatial resolution in en face and cross-sectional views that provides a label-free, non-invasive platform with high-resolution 3D imaging. We validated the imaging power of this prototype by ...

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    6. Dermal Epidermal Junction Detection for Full-Field Optical Coherence Tomography Data of Human Skin by Deep Learning

      Dermal Epidermal Junction Detection for Full-Field Optical Coherence Tomography Data of Human Skin by Deep Learning

      Full-field optical coherence tomography (FF-OCT) has been developed to obtain three-dimensional (3D) OCT data of human skin for early diagnosis of skin cancer. Detection of dermal epidermal junction (DEJ), where melanomas and basal cell carcinomas originate, is an essential step for skin cancer diagnosis. However, most existing DEJ detection methods consider each cross-sectional frame of the 3D OCT data independently, leaving the relationship between neighboring frames unexplored. In this paper, we exploit the continuity of 3D OCT data to enhance DEJ detection. In particular, we propose a method for noise reduction of the training data and a multi-directional convolutional neural ...

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    7. Direct inverse linearization of piezoelectric actuator’s initial loading curve and its applications in full-field optical coherence tomography (FF-OCT)

      Direct inverse linearization of piezoelectric actuator’s initial loading curve and its applications in full-field optical coherence tomography (FF-OCT)

      Abstract Piezoelectric actuator (PEA) has become popular in spectroscopic optical coherence tomography (SOCT) as it can provide depth dependent spectra with sub‐nanometer positioning resolution. However, the inherent hysteresis of the PEA introduces unwanted distortions to the obtained spectra and image. OCT imaging can be completed during the first forward motion of the PEA, i.e., the initial loading curve (ILC). Therefore, this paper proposes a feedforward hysteresis compensation method for the linearization of the ILC, aiming at improving the spectroscopic and imaging accuracy of OCT without any feedback on the PEA’s displacement or feedback controllers. A polynomial operator ...

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    8. En Face and Cross-sectional Corneal Tomograms Using Sub-micron spatial resolution Optical Coherence Tomography

      En Face and Cross-sectional Corneal Tomograms Using Sub-micron spatial resolution Optical Coherence Tomography

      Accurate diagnosis of corneal pathology and morphological identification of different corneal layers require clear delineation of corneal three-dimensional structures and en face or cross-sectional imaging of palisade of Vogt (POV), neovascularization (NV) or corneal nerves. Here we report a prototype of full-field optical coherence tomography (FF-OCT) system with isotropic sub-micron spatial resolution in the en face and cross-sectional views. It can also provide three-dimensional reconstructed images and a large field of view (FOV) by stitching tomograms side by side. We validated the imaging power of this prototype in in vivo rat and rabbit eyes, and quantified anatomical characteristics such as ...

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    9. Feature Of The Week 08/31/2018: Spectroscopic Characterization of Si/Mo Thin-film Stack at Extreme Ultraviolet Range

      Feature Of The Week 08/31/2018: Spectroscopic Characterization of Si/Mo Thin-film Stack at Extreme Ultraviolet Range

      Using extreme ultraviolet (EUV) radiation for nanoscale imaging has recently seen much interest. As actinic patterned mask inspection tools are not available, chipmakers have to rely on wafer inspection to identify mask defects. To fulfill the requirements of mask inspection, EUV sources with high brightness, high stability (spatial and temporal), and cost effectiveness are needed. In a laser-produced-plasma (LPP) generated EUV system, a high-intensity laser beam is focused onto a tin target to form a hot plasma, which emits ultraviolet light. In this study, a fiber-laser excitation source was used to generate stable 13.5-nm EUV for spectroscopic optical coherence ...

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    10. Spectroscopic characterization of Si/Mo thin-film stack at extreme ultraviolet range

      Spectroscopic characterization of Si/Mo thin-film stack at extreme ultraviolet range

      A noninvasive method for characterizing Si/Mo thin-film stack thickness and its complex transfer function using common-path optical coherence tomography is proposed, analyzed, and experimentally demonstrated. A laser-produced plasma (LPP)-based extreme ultraviolet (EUV) source was excited by a four-stage nanosecond Yb:fiber laser amplifier with a pulse energy of 1.01 mJ. The tabletop LPP EUV source was compact and stable for generating the EUV interference fringes. The measured complex transfer function of the Si/Mo stack was verified near the pristine 13.5-nm wavelength range.

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    11. Extracting Blood Vessels From Full-Field OCT Data of Human Skin by Short-Time RPCA

      Extracting Blood Vessels From Full-Field OCT Data of Human Skin by Short-Time RPCA

      Recent advances in optical coherence tomography (OCT) lead to the development of OCT angiography to provide additional helpful information for diagnosis of diseases like basal cell carcinoma. In this paper, we investigate how to extract blood vessels of human skin from full-field OCT (FF-OCT) data using the robust principal component analysis (RPCA) technique. Specifically, we propose a short-time RPCA method that divides the FF-OCT data into segments and decomposes each segment into a low-rank structure representing the relatively static tissues of human skin and a sparse matrix representing the blood vessels. The method mitigates the problem associated with the slow-varying ...

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    12. Three-dimensional optical coherence tomography apparatus and its application

      Three-dimensional optical coherence tomography apparatus and its application

      Provided herein are devices and systems that apply full-field optical coherence tomography (OCT) technology to three-dimensional skin tissue imaging. A special designed Mirau type objective and an optical microscope module allowing both OCT mode and orthogonal polarization spectral imaging (OPSI) mode are disclosed.

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    13. Feature of The Week 03/26.2017: Segmentation of nucleus and cytoplasm of a single cell in 3D tomogram using OCT

      Feature of The Week 03/26.2017: Segmentation of nucleus and cytoplasm of a single cell in 3D tomogram using OCT

      uclear-to-cytoplasmic (N/C) ratio is an effective feature to distinguish cancer cells from their normal counterparts. In conventional cytopathology, cells printed or smeared on a glass slide were stained and then evaluated by two-dimensional (2D) images through light microscopy. A random rayburst sampling (RRBS) framework was developed to detect the nucleus and cell membrane boundaries in three-dimensional (3D) space. Raw images were acquired through a full-field optical coherence tomography (FF-OCT) system with submicron resolution—i.e. 0.8 µm in lateral and 0.9 µm in axial direction. The near isometric resolution enables 3D segmentation of nucleus and cell membrane ...

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    14. Segmentation of nucleus and cytoplasm of a single cell in three-dimensional tomogram using optical coherence tomography

      Segmentation of nucleus and cytoplasm of a single cell in three-dimensional tomogram using optical coherence tomography

      A random rayburst sampling (RRBS) framework was developed to detect the nucleus and cell membrane boundaries in three-dimensional (3-D) space. Raw images were acquired through a full-field optical coherence tomography system with submicron resolution—i.e., 0.8    μ m 0.8  μm in lateral and 0.9    μ m 0.9  μm in axial directions. The near-isometric resolution enables 3-D segmentation of a nucleus and cell membrane for determining the volumetric nuclear-to-cytoplasmic (N/C) ratio of a single cell. The RRBS framework was insensitive to the selection of seeds and image pixel noise. The robustness of the RRBS framework was verified ...

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    15. Feature Of The Week 9/28/14: National Taiwan University Reports on Full-depth epidermis tomography using a Mirau-based full-field OCT

      Feature Of The Week 9/28/14: National Taiwan University Reports on Full-depth epidermis tomography using a Mirau-based full-field OCT

      All living things are made of cells. Most living organisms are single cells; others, such as human bodies, are vast multicellular cities with an aggregation of more than 10 billion cells. Non-invasive and high speed imaging of cells and tissues with sub-micron resolution could help unveil functions of living organisms, and facilitate disease/cancer diagnosis, new drug development, etc. Such an imaging modality is one of the key technologies to detect disease and cancer in the early stage so that the ever-escalating medical cost could be controlled. At the same time, biomedical discovery often originated from technology advancement. Optical coherence ...

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    16. Full-depth epidermis tomography using a Mirau-based full-field optical coherence tomography

      Full-depth epidermis tomography using a Mirau-based full-field optical coherence tomography

      With a Gaussian-like broadband light source from high brightness Ce 3+ :YAG single-clad crystal fiber, a full-field optical coherence tomography using a home-designed Mirau objective realized high quality images of in vivo and excised skin tissues. With a 40 × silicone-oil-immersion Mirau objective, the achieved spatial resolutions in axial and lateral directions were 0.9 and 0.51 μm, respectively. Such a high spatial resolution enables the separation of lamellar structure of the full epidermis in both the cross-sectional and en face planes. The number of layers of stratum corneum and its thickness were quantitatively measured. This label free and non-invasive ...

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    17. Fabrication and Characteristics of Ce-Doped Fiber for High-Resolution OCT Source

      Fabrication and Characteristics of Ce-Doped Fiber for High-Resolution OCT Source

      The fabrication of Ce-doped fibers (CeDFs) is demonstrated by drawing-tower method employing rod-in-tube technique. The fluorescence spectrum of CeDFs with a 16-μm core exhibited a 160-nm broadband emission with 1.45-μm axial resolution. This CeDF may be functioned as a high-resolution light source for optical coherence tomography applications.

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    18. 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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    19. Apparatus for low coherence optical imaging

      Apparatus for low coherence optical imaging

      The present invention relates to an apparatus for low coherence optical imaging, and more particularly to an apparatus for low coherence optical imaging which can obtain the information of the different depths of a sample simultaneously. The apparatus comprises a phase transformation unit or a beam shift unit. The phase transformation unit or beam shift unit transforms and reflects the reference light, such that the reflected reference light comprises different phases at the different positions of a cross-section. When the reference light and a information light from the sample are superimposed on a photo detector, the information of the different ...

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    20. Three-dimensional optical coherence tomography confocal imaging apparatus

      Three-dimensional optical coherence tomography confocal imaging apparatus

      A 3D OCT confocal imaging apparatus includes a light source module for providing an illumination beam with wider bandwidth from a crystal fiber; a reference source module; a pickup module; a beam splitter; an optical filter; and a sensor module. When the illumination beam illuminates a sample, a pickup objective lens and a piezoelectric actuator of the pickup module together provide an image beam scanning the sample in depth direction. The image beam and a reference beam from the reference source module together form an interference image beam, which is converted by a photosensor into a coherence image electric signal ...

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    21. Optical imaging apparatus and method

      Optical imaging apparatus and method

      The present invention relates to an optical imaging apparatus and a method, and more particularly to an optical imaging apparatus and a method with short coherence length optical source. The apparatus comprises an optical source with a plurality of outputs for providing a reference light and a sample light; a sample probe module for leading the sample light to a sample, and leading an information light out; an interference module for leading the reference light to a photo detector, and leading the information light to the photo detector; and a signal processing unit electrically coupled to the photo detector; wherein ...

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    22. Mirau-based full-field time-domain optical coherence tomography using Ce3+ :YAG crystal fiber light source

      Mirau-based full-field time-domain optical coherence tomography using Ce3+ :YAG crystal fiber light source

      Based on single-objective construction utilizing high brightness Ce 3+ :YAG single-clad crystal fiber light source, this Mirau-based full-field time-domain optical coherence tomography with circular polarization incident light represents deeper penetration in scattering medium. Using objective-changeable ability of home-designed Mirau objective, this system provides different applications, like biological tissue and single cells, by different spatial resolution with corresponding dynamics. High quality image relying on less ghost image and near common-path interference was demonstrated under this compact and power-stable system.

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    23. Full EM wave simulation on optical coherence tomography: impact of surface roughness

      Full EM wave simulation on optical coherence tomography: impact of surface roughness

      In this paper we attempted to simulate the macroscopic light scattering phenomenon of optical coherence tomography. Numerical solutions of Maxwell’s equations were computed to accurately account for phase and amplitude of light. According to the simulation results, the qualitative and quantitative characterization may provide important information for future development of this technique, especially on the index mapping of biological cells.

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    24. Feature Of The Week 10/21/12: Cell Death Detection by Quantitative Three-Dimensional Single-Cell Tomography

      Feature Of The Week 10/21/12: Cell Death Detection by Quantitative Three-Dimensional Single-Cell Tomography


      The aim of cancer therapies is mainly to stop cell proliferation or induce cell death. Cell death regulation is important for normal development and homeostasis. Cancer cells escape from death signals and continue their abnormal proliferation. Therefore, the ability to induce death in cancer cells has been a crucial biomarker for the efficacy of chemotherapeutic agents. However, individual cancer cells, even from the same population, vary greatly in their response to cell death stimuli. Measuring the response at the single-cell levels provide further pharmacokinetic and pharmacodynamics information, which aids drug development and regimen design. Developing a microscopic technology with non-invasive ...

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    1-24 of 33 1 2 »
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