1. Articles from Changho Lee

    1-19 of 19
    1. 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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    2. Ophthalmic laser system integrated with speckle variance optical coherence tomography for real-time temperature monitoring

      Ophthalmic laser system integrated with speckle variance optical coherence tomography for real-time temperature monitoring

      A commercial ophthalmic laser system (R;GEN, Lutronic Corp) was integrated with a swept-source optical coherence tomography (OCT) imaging system for real-time tissue temperature monitoring. M-scan OCT images were acquired during laser-pulse radiation, and speckle variance OCT (svOCT) images were analyzed to deduce temporal signal variations related to tissue temperature change from laser-pulse radiation. A phantom study shows that svOCT magnitude increases abruptly after laser pulse radiation and recovered exponentially, and the peak intensity of svOCT image was linearly dependent on pulse laser energy until it saturates. A study using bovine iris also showed signal variation dependence on the laser ...

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    3. In vivo observation of metamorphosis of Plodia interpunctella Hübner using three-dimensional optical coherence tomography

      In vivo observation of metamorphosis of Plodia interpunctella Hübner using three-dimensional optical coherence tomography

      Morphological assessment and three-dimensional reconstructions of internal structures of Plodia interpunctella Hübner during metamorphosis stages were experimentally demonstrated using optical coherence tomography (OCT) for the first time. The conventional, complex sectioning methods were significantly simplified owing to the non-invasive three-dimensional imaging capability of OCT. Further, this study demonstrates the use of OCT as a non-invasive detection tool for in vivo morphological observation of metamorphosis stages to gain a better understanding about the growth of internal organs, which can be considered a useful discovery in the field of entomology. Thus, the metamorphosis stages starting from the larva, three pupa stages ...

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    4. Feasibility study: protein denaturation and coagulation monitoring with speckle variance optical coherence tomography

      Feasibility study: protein denaturation and coagulation monitoring with speckle variance optical coherence tomography

      We performed the feasibility study using speckle variance optical coherence tomography (SvOCT) to monitor the thermally induced protein denaturation and coagulation process as a function of temperature and depth. SvOCT provided the depth-resolved image of protein denaturation and coagulation with microscale resolution. This study was conducted using egg white. During the heating process, as the temperature increased, increases in the speckle variance signal was observed as the egg white proteins coagulated. Additionally, by calculating the cross-correlation coefficient in specific areas, denaturized egg white conditions were successfully estimated. These results indicate that SvOCT could be used to monitor the denaturation process ...

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    5. Non-invasive method and apparatus for screening high-quality seeds

      Non-invasive method and apparatus for screening high-quality seeds

      Disclosed is a method and apparatus for the non-invasive selection of high-quality seeds, based on optical coherence tomography, by which pathogen-infected and pathogen-free seeds can be discriminated in a non-invasive manner. The apparatus is operated by the processes of scanning a seed of diagnostic interest in a non-invasive manner using an optical coherence tomographic unit; processing interference signals of the scanned tomographic images to produce tomographic image data of the seed of diagnostic interest; analyzing the tomographic image data; comparing the analyzed tomographic image data with preset reference tomographic image data; diagnosing the seed of diagnostic interest as a pathogen-infected ...

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    6. In Vivo Near Infrared Virtual Intraoperative Surgical Photoacoustic Optical Coherence Tomography

      In Vivo Near Infrared Virtual Intraoperative Surgical Photoacoustic Optical Coherence Tomography

      Since its first implementation in otolaryngological surgery nearly a century ago, the surgical microscope has improved the accuracy and the safety of microsurgeries. However, the microscope shows only a magnified surface view of the surgical region. To overcome this limitation, either optical coherence tomography (OCT) or photoacoustic microscopy (PAM) has been independently combined with conventional surgical microscope. Herein, we present a near-infrared virtual intraoperative photoacoustic optical coherence tomography (NIR-VISPAOCT) system that combines both PAM and OCT with a conventional surgical microscope. Using optical scattering and absorption, the NIR-VISPAOCT system simultaneously provides surgeons with real-time comprehensive biological information such as tumor ...

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    7. Two-axis polydimethylsiloxane-based electromagnetic microelectromechanical system scanning mirror for optical coherence tomography

      Two-axis polydimethylsiloxane-based electromagnetic microelectromechanical system scanning mirror for optical coherence tomography

      Compact size and fast imaging abilities are key requirements for the clinical implementation of an optical coherence tomography (OCT) system. Among the various small-sized technology, a microelectromechanical system (MEMS) scanning mirror is widely used in a miniaturized OCT system. However, the complexities of conventional MEMS fabrication processes and relatively high costs have restricted fast clinical translation and commercialization of the OCT systems. To resolve these problems, we developed a two-axis polydimethylsiloxane (PDMS)-based MEMS (2A-PDMS-MEMS) scanning mirror through simple processes with low costs. It had a small size of 15 × 15 × 15    mm 3 15×15×15  mm3 , was fast ...

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    8. A 2-axis Polydimethylsiloxane (PDMS) based electromagnetic MEMS scanning mirror for optical coherence tomography

      A 2-axis Polydimethylsiloxane (PDMS) based electromagnetic MEMS scanning mirror for optical coherence tomography

      Optical coherence tomography (OCT) is a noninvasive imaging tool for visualizing cross-sectional images of biological tissues on a microscale. Various microelectromechanical system (MEMS) techniques have been applied to OCT for endoscopic catheters and handheld probes. Despite having several advantages such as compact sizes and high speeds for real-time imaging, the complexities of the fabrication processes and relatively high costs were bottlenecks for fast clinical translation and commercialization of the earlier MEMS scanners. To overcome these issues, we developed a 2-axis polydimethylsiloxane (PDMS)-based electromagnetic MEMS scanning mirror based on flexible, cost-effective, and handleable PDMS. The size of this MEMS scanner ...

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    9. Microscope System, And Method For Providing Augmented Reality Images Of Microscope System

      Microscope System, And Method For Providing Augmented Reality Images Of Microscope System

      Provided is a microscope system. The system comprises: an optical microscope unit for collecting a surface image of an object to be examined; an OCT unit for collecting an optical coherence tomography image of the object to be examined; a PA unit for collecting a photoacoustic image of the object to be examined; an image processing unit for generating an augmented reality image by superimposing the optical coherence tomography image and the photoacoustic image over the surface image; and an image observation unit for making the augmented reality image visible.

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    10. Stimulated penetrating keratoplasty using real-time virtual intraoperative surgical optical coherence tomography

      Stimulated penetrating keratoplasty using real-time virtual intraoperative surgical optical coherence tomography

      An intraoperative surgical microscope is an essential tool in a neuro- or ophthalmological surgical environment. Yet, it has an inherent limitation to classify subsurface information because it only provides the surface images. To compensate for and assist in this problem, combining the surgical microscope with optical coherence tomography (OCT) has been adapted. We developed a real-time virtual intraoperative surgical OCT (VISOCT) system by adapting a spectral-domain OCT scanner with a commercial surgical microscope. Thanks to our custom-made beam splitting and image display subsystems, the OCT images and microscopic images are simultaneously visualized through an ocular lens or the eyepiece of ...

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    11. Combined photoacoustic and optical coherence tomography using a single near-infrared supercontinuum laser source

      Combined photoacoustic and optical coherence tomography using a single near-infrared supercontinuum laser source

      . We developed an integrated dual-modal photoacoustic and optical coherence tomography (PA-OCT) system using a single near-infrared supercontinuum laser source to simultaneously provide both optical absorption and scattering contrasts. A pulsed broadband supercontinuum source was generated by a pulsed Nd:YAG laser and a photonic-crystal fiber. When we imaged two colored hairs, the black hair was visible in both PA and OCT images, whereas the white hair was only mapped in the OCT image. The single laser source will potentially allow us to implement relatively simple, cheap, and compact dual-modal PA-OCT systems, which are key criteria for fast clinical translation and ...

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    12. Dual-modal photoacoustic and optical coherence tomography using a single near-infrared supercontinuum laser source

      Dual-modal photoacoustic and optical coherence tomography using a single near-infrared supercontinuum laser source

      We report the development of a combined dual-modal photoacoustic and optical coherence tomography (PA-OCT) system using a single near-infrared (NIR) supercontinuum laser source which can provide both optical absorption and scattering contrasts simultaneously. By using a small sized pulsed Nd:YAG microchip laser and a photonic crystal fiber, we fabricated a pulsed broadband supercontinuum source from 600 to 1700 nm. Under the same optical hardware system, intrinsically registered PA and OCT images are acquired in a single scanning. In order to demonstrate feasibility of our system, we successfully acquired the PA and OCT images of black and white hairs images ...

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    13. Method And Device For Early Non-Invasive Diagnose Of Fruit Tree Disease

      Method And Device For Early Non-Invasive Diagnose Of Fruit Tree Disease

      The present invention relates to a non-invasive early diagnostic method and device that allows an early diagnosis of Marssonina blotch disease, which infects apple tree leaves, before the occurrence of lesions to enable early prevention of apple Marssonina blotch disease. The method and device of the present invention comprise the following steps: irradiating a broadband light source on an apple tree leaf undergoing diagnosis by means of optical coherence tomography; detecting interference signals from light reflected from the apple tree leaf undergoing diagnosis and light reflected from a reference arm; signal processing the interference signals, which have been detected through ...

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    14. Application of optical coherence tomography to detect Cucumber green mottle mosaic virus (CGMMV) infected cucumber seed

      Application of optical coherence tomography to detect Cucumber green mottle mosaic virus (CGMMV) infected cucumber seed

      Abstract  In this study, we distinguished Cucumber green mottle mosaic virus (CGMMV) infected seeds from healthy seeds using optical coherence tomography (OCT). Two dimensional OCT images and stereo micrographs revealed that the infected seeds had narrow gap between the seed coat and endosperm that were not present in the healthy seeds. Three dimensional OCT images confirmed that the narrow gaps were present in the inner structure of overall the infected seeds. A-scan analysis was also performed to calculate the distance from the seed coat to the endosperm. The results revealed a difference in the width of the gap of about ...

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    15. Pulsed magneto-motive optical coherence tomography for remote cellular imaging

      Pulsed magneto-motive optical coherence tomography for remote cellular imaging

      We developed pulsed magneto-motive optical coherence tomography (PMM-OCT) to reduce environmental temperature in the measurement volume and to expand the effective magnetic field distance from a pulse source. The proposed PMM-OCT system consisted of a spectral-domain OCT system and a customarily designed electrical pulse generator. The enhanced magnetic field allowed the proposed system to be able to image magnetically labeled cells in a distance as far as 30 mm away from the pulse generator. As an easy and sensitive approach, our PMM-OCT may be beneficially applied to a molecular-level imaging systems.

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    16. Ultra-Fast Displaying Spectral Domain Optical Doppler Tomography System Using a Graphics Processing Unit

      Ultra-Fast Displaying Spectral Domain Optical Doppler Tomography System Using a Graphics Processing Unit

      We demonstrate an ultrafast displaying Spectral Domain Optical Doppler Tomography system using Graphics Processing Unit (GPU) computing. The calculation of FFT and the Doppler frequency shift is accelerated by the GPU. Our system can display processed OCT and ODT images simultaneously in real time at 120 fps for 1,024 pixels × 512 lateral A-scans. The computing time for the Doppler information was dependent on the size of the moving average window, but with a window size of 32 pixels the ODT computation time is only 8.3 ms, which is comparable to the data acquisition time. Also the phase noise ...

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    17. Optical Sensing Method for Screening Disease in Melon Seeds by Using Optical Coherence Tomography

      Optical Sensing Method for Screening Disease in Melon Seeds by Using Optical Coherence Tomography

      We report a noble optical sensing method to diagnose seed abnormalities using optical coherence tomography (OCT). Melon seeds infected with Cucumber green mottle mosaic virus (CGMMV) were scanned by OCT. The cross-sectional sensed area of the abnormal seeds showed an additional subsurface layer under the surface which is not found in normal seeds. The presence of CGMMV in the sample was examined by a blind test (n = 140) and compared by the reverse transcription-polymerase chain reaction. The abnormal layers (n = 40) were quantitatively investigated using A-scan sensing analysis and statistical method. By utilizing 3D OCT image reconstruction, we confirmed the ...

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    18. Pulse Analyzing System Using Optical Coherence Tomography for Oriental Medical Application

      Pulse Analyzing System Using Optical Coherence Tomography for Oriental Medical Application

      In oriental medicine, the pulse wave of a radial artery is a critical diagnosis factor. An oriental doctor puts a finger on the radial artery to sense the pulse wave of a radial artery. The pulse wave plays an important role because its shape, pressure, and duration determine the pathological status of a patient. Chongumaekbeop, which is a traditional technique for measuring the pulse by using a finger, is sometimes believed to be not reproducible due to the subjective judgment of the measurement location and pulse signal, so we performed a clinical experiment with a developed diagnosis equipment to produce ...

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    19. Full-range k-domain linearization in spectral-domain optical coherence tomography

      Full-range k-domain linearization in spectral-domain optical coherence tomography

      A full-bandwidth k-domain linearization method for spectral-domain optical coherence tomography (SD-OCT) is demonstrated. The method uses information of the wavenumber–pixel-position provided by a translating-slit-based wavelength filter. For calibration purposes, the filter is placed either after a broadband source or at the end of the sample path, and the filtered spectrum with a narrowed line width (∼0.5 nm) is incident on a line-scan camera in the detection path. The wavelength-swept spectra are co-registered with the pixel positions according to their central wavelengths, which can be automatically measured with an optical spectrum analyzer. For imaging, the method does not require ...

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    1-19 of 19
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  2. Topics in the News

    1. (19 articles) Changho Lee
    2. (17 articles) Jeehyun Kim
    3. (15 articles) Kyungpook National University
    4. (6 articles) Mansik Jeon
    5. (2 articles) Johns Hopkins University
    6. (2 articles) State University of New York at Buffalo
    7. (2 articles) Ruchire Eranga Wijesinghe
    8. (2 articles) Jin U. Kang
    9. (2 articles) Santec
    10. (1 articles) Stephen A. Boppart
    11. (1 articles) Harvard University
    12. (1 articles) Massachusetts General Hospital
    13. (1 articles) University of North Carolina
    14. (1 articles) Baylor College of Medicine
    15. (1 articles) Masamichi Takano
    16. (1 articles) Joel S. Schuman
    17. (1 articles) Ik-Kyung Jang
    18. (1 articles) Yoshiyasu Minami
    19. (1 articles) Donald L. Budenz
    20. (1 articles) Gadi Wollstein
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    Full-range k-domain linearization in spectral-domain optical coherence tomography Pulse Analyzing System Using Optical Coherence Tomography for Oriental Medical Application Optical Sensing Method for Screening Disease in Melon Seeds by Using Optical Coherence Tomography Ultra-Fast Displaying Spectral Domain Optical Doppler Tomography System Using a Graphics Processing Unit Pulsed magneto-motive optical coherence tomography for remote cellular imaging Application of optical coherence tomography to detect Cucumber green mottle mosaic virus (CGMMV) infected cucumber seed Dual-modal photoacoustic and optical coherence tomography using a single near-infrared supercontinuum laser source Combined photoacoustic and optical coherence tomography using a single near-infrared supercontinuum laser source Method And Device For Early Non-Invasive Diagnose Of Fruit Tree Disease A 2-axis Polydimethylsiloxane (PDMS) based electromagnetic MEMS scanning mirror for optical coherence tomography High space-bandwidth in quantitative phase imaging using partially spatially coherent optical coherence microscopy and deep neural network Optical coherence tomography assessment of macrophages accumulation in non-ST-segment elevation acute coronary syndromes