1. Articles from Sangyeob Han

    1-6 of 6
    1. Dynamic compensation of path length difference in optical coherence tomography by an automatic temperature control system of optical fiber

      Dynamic compensation of path length difference in optical coherence tomography by an automatic temperature control system of optical fiber

      Optical fiber is widely used in optical coherence tomography (OCT) to propagate light precisely with low attenuation and low dispersion. However, the total optical path length within the optical fiber varies in accordance with changes of the temperature. This leads changes in the total optical travel path of the interfering signals and results in shifting of OCT image position to an unintended depth pixel value. In this paper, we presented the temperature-based automatic path length compensating method in OCT to limit the external temperature effect and control the image position in micro-scale without manual movement of optical components. By utilizing ...

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    2. Optical Interferometric Fringe Pattern-Incorporated Spectrum Calibration Technique for Enhanced Sensitivity of Spectral Domain Optical Coherence Tomography

      Optical Interferometric Fringe Pattern-Incorporated Spectrum Calibration Technique for Enhanced Sensitivity of Spectral Domain Optical Coherence Tomography

      Depth-visualizing sensitivity can be degraded due to imperfect optical alignment and non-equidistant distribution of optical signals in the pixel array, which requires a measurement of the re-sampling process. To enhance this depth-visualizing sensitivity, reference and sample arm-channeled spectra corresponding to different depths using mirrors were obtained to calibrate the spectrum sampling prior to Fourier transformation. During the process, eight interferogram patterns corresponding to point spread function (PSF) signals at eight optical path length differences were acquired. To calibrate the spectrum, generated intensity points of the original interferogram were re-indexed towards a maximum intensity range, and these interferogram re-indexing points were ...

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    3. Identification of multi-dimensional thread geometry using depth-resolved swept-source optical coherence tomography for assessment of dental implant fabrication

      Identification of multi-dimensional thread geometry using depth-resolved swept-source optical coherence tomography for assessment of dental implant fabrication

      The geometrical characteristics of dental implants, such as thread depth and width, facing angle, pitch, and surface roughness, are important to assess their stability and osseointegration after implant surgery. Herein, we demonstrate the potential use of depth-resolved swept-source optical coherence tomography (SS-OCT) to assess the structural quality of widely used dental implants. The implemented SS-OCT system was centered at a wavelength of 1300 nm with a 100 nm full-width at half-maximum. Four dental implants with different structural formations fabricated using either titanium or ceramic were visualized. Qualitative assessments were performed using boundary flattening with an amplitude-profiling algorithm to emphasize and ...

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    4. An averaged intensity difference detection algorithm for identification of human gingival sulcus in optical coherence tomography images

      An averaged intensity difference detection algorithm for identification of human gingival sulcus in optical coherence tomography images

      In the past decade, there has been an increase in the development of sensitive, highresolution, non-invasive diagnostic methods for periodontic diseases. Optical coherence tomography (OCT) has attracted considerable attention in clinical settings. In this study, a reliable, robust algorithm for the detection of gingival sulcus in 2D OCT cross-sectional images is proposed. Previously, the measurement of gingival sulcus in OCT images has been performed by manual identification using two-dimensional (2D) cross-sectional images. The automated detection of gingival sulcus continuity in 2D OCT images may help medical practitioners to assess important features of gingival tissues. The Sobel and canny operators have ...

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    5. Numerical-Sampling-Functionalized Real-Time Index Regulation for Direct k-Domain Calibration in Spectral Domain Optical Coherence Tomography

      Numerical-Sampling-Functionalized Real-Time Index Regulation for Direct k-Domain Calibration in Spectral Domain Optical Coherence Tomography

      An index-regulation technique functionalized by numerical sampling for direct calibration of the non-linear wavenumber ( k )-domain to a linear domain in spectral domain optical coherence tomography (SD-OCT) is proposed. The objective of the developed method is to facilitate high-resolution identification of microstructures in biomedical imaging. Subjective optical alignments caused by nonlinear sampling of interferograms in the k -domain tend to hinder depth-dependent signal-to-noise ratios (SNR) and axial resolution in SD-OCT. Moreover, the optical-laser-dependent k -domain requires constant recalibrated in accordance with each laser transition, thereby necessitating either hardware or heavy software compensations. As the key feature of the proposed method ...

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    6. 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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    1-6 of 6
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  2. Topics in the News

    1. (6 articles) Kyungpook National University
    2. (6 articles) Jeehyun Kim
    3. (6 articles) Ruchire Eranga Wijesinghe
    4. (6 articles) Mansik Jeon
    5. (3 articles) National Institutes of Health
    6. (2 articles) Naresh Kumar Ravichandran
    7. (2 articles) Harvard University
    8. (1 articles) Changho Lee
    9. (1 articles) Texas A&M University
    10. (1 articles) FDA
    11. (1 articles) University of Southern California
    12. (1 articles) Dresden University of Technology
    13. (1 articles) Francesco Prati
    14. (1 articles) Edmund Koch
    15. (1 articles) Lars Kirsten
    16. (1 articles) Javier A. Jo
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    Fast Industrial Inspection of Optical Thin Film Using Optical Coherence Tomography Numerical-Sampling-Functionalized Real-Time Index Regulation for Direct k-Domain Calibration in Spectral Domain Optical Coherence Tomography An averaged intensity difference detection algorithm for identification of human gingival sulcus in optical coherence tomography images Identification of multi-dimensional thread geometry using depth-resolved swept-source optical coherence tomography for assessment of dental implant fabrication Optical Interferometric Fringe Pattern-Incorporated Spectrum Calibration Technique for Enhanced Sensitivity of Spectral Domain Optical Coherence Tomography Dynamic compensation of path length difference in optical coherence tomography by an automatic temperature control system of optical fiber Medical treatment of inflammatory punctual stenosis monitored by anterior segment optical coherence tomography Development and Validation of a Deep Learning System for Diagnosing Glaucoma Using Optical Coherence Tomography Methylene blue-filled biodegradable polymer particles as a contrast agent for optical coherence tomography Optical coherence tomography for thyroid pathology: 3D analysis of tissue microstructure Mathematical Analysis of Texture Indicators for the Segmentation of Optical Coherence Tomography Images Comparison of Current Optical Coherence Tomography Angiography Methods in Imaging Retinal Hemangioblastomas