1. Articles from Sang-Won Lee

    1-19 of 19
    1. Retina phantom for the evaluation of optical coherence tomography angiography based on microfluidic channels

      Retina phantom for the evaluation of optical coherence tomography angiography based on microfluidic channels

      Optical coherence tomography (OCT) angiography (OCTA) has been actively studied as a noninvasive imaging technology to generate retinal blood vessel network maps for the diagnoses of retinal diseases. Given that the uses of OCT and OCTA have increased in the field of ophthalmology, it is necessary to develop retinal phantoms for clinical OCT for product development, performance evaluation, calibration, certification, medical device licensing, and production processes. We developed a retinal layer-mimicking phantom with microfluidic channels based on microfluidic fabrication technology using polydimethylsiloxane (PDMS) and titanium dioxide (TiO 2 ) powder. We implemented superficial and deep retinal vessels using microfluidic channels. In ...

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      Mentions: Sang-Won Lee
    2. Stacked Gold Nanodisks for Bimodal Photoacoustic and Optical Coherence Imaging

      Stacked Gold Nanodisks for Bimodal Photoacoustic and Optical Coherence Imaging

      Herein, we report on biological imaging nanoprobes: physically-synthesized gold nanodisks that have inherent optical advantages—a wide range of resonant wavelengths, tunable ratio of light absorption-to-scattering, and responsiveness to random incident light—due to their two-dimensional circular nanostructure. Based on our proposed physical synthesis where gold is vacuum-deposited onto a pre-patterned polymer template and released from the substrate in the form of a nanodisk, monodisperse two-dimensional gold nanodisks were prepared with independent control of their diameter and thickness. The optical benefits of the Au nanodisk were successfully demonstrated by the measurement of light absorbance of the nanodisks and the application ...

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      Mentions: Sang-Won Lee
    3. Intraocular application of gold nanodisks optically tuned for optical coherence tomography: inhibitory effect on retinal neovascularization without unbearable toxicity

      Intraocular application of gold nanodisks optically tuned for optical coherence tomography: inhibitory effect on retinal neovascularization without unbearable toxicity

      Bare gold nanospheres have been shown to have anti-angiogenic effects but are optically unfavorable because their resonant wavelength lies in the visible spectrum. Here, we design gold nanodisks with a higher scattering capability than gold nanorods and with a resonant wavelength at near-infrared region – the area where the source of light utilized by optical coherence tomography (OCT) lies. With a physical synthesis system, we then fabricate 160-nm-sized gold nanodisks exhibiting resonant wavelength at 830 nm. The synthesized nanoparticles were successfully visualized in in vivo OCT at concentrations as low as 1 pM. After demonstrating their binding ability to vascular endothelial ...

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      Mentions: Sang-Won Lee
    4. Ultrahigh-Resolution Spectral Domain Optical Coherence Tomography Based on a Linear-Wavenumber Spectrometer

      Ultrahigh-Resolution Spectral Domain Optical Coherence Tomography Based on a Linear-Wavenumber Spectrometer

      In this study we demonstrate ultrahigh-resolution spectral domain optical coherence tomography (UHR SD-OCT) with a linear-wavenumber (k) spectrometer, to accelerate signal processing and to display two-dimensional (2-D) images in real time. First, we performed a numerical simulation to find the optimal parameters for the linear-k spectrometer to achieve ultrahigh axial resolution, such as the number of grooves in a grating, the material for a dispersive prism, and the rotational angle between the grating and the dispersive prism. We found that a grating with 1200 grooves and an F2 equilateral prism at a rotational angle of 26.07°, in combination with ...

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    5. Optics for forming a linear beam in optical coherence tomography

      Optics for forming a linear beam in optical coherence tomography

      This invention relates to an optical coherence tomography, in which a light source and an optical linear beam forming system are adopted to obtain two dimensional image of high quality resolution within short time without affection by any mechanical movements. For such purpose, the optical linear beam forming system (20) comprises semicy Under lens (21), convex lens (22) and slit (23) to implement the frequency domain optical coherence tomography. Parallel light beam from the light source is incident on the surface of the semicylinder lens (21), and focal line of the semicylinder lens (21) is located in front of the ...

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    6. Optical Monitoring of Tumors in BALB/c Nude Mice Using Optical Coherence Tomography

      Optical Monitoring of Tumors in BALB/c Nude Mice Using Optical Coherence Tomography

      We report a method for optical monitoring of tumors in an animal model using optical coherence tomography (OCT). In a spectral domain OCT system, a superluminescent diode light source with a full width of 66 nm at half maximum and peak wavelength of 950 nm was used to take images having an axial resolution of 6.8 μ m. Cancer cells of PC-3 were cultured and inoculated into the hypodermis of auricle tissues in BALB/c nude mice. We observed tumor formation and growth at the injection region of cancer cells in vivo and obtained the images of tumor mass center ...

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    7. Spectral-domain OCT with dual illumination and interlaced detection for simultaneous anterior segment and retina imaging

      Spectral-domain OCT with dual illumination and interlaced detection for simultaneous anterior segment and retina imaging

      We present Fourier-domain/spectral-domain optical coherence tomography (FD/SD-OCT) using a single spectrometer with dual illumination and interlaced detection at 830 nm, which can provide anterior segment and retinal tomograms simultaneously. Two orthogonal polarization components were used so that both parallel and focused beams could simultaneously be made incident on the eye. This configuration with a polarization-separated sample arm enables us to acquire images from the anterior segment and retina effectively with minimum loss of sample information. In the detector arm, a single spectrometer is illuminated via an ultrafast optical switch for interlaced detection. A graphical user interface (GUI) was ...

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    8. Investigating in vivo airway wall mechanics during tidal breathing with optical coherence tomography

      Investigating in vivo airway wall mechanics during tidal breathing with optical coherence tomography
      Optical coherence tomography (OCT) is a nondestructive imaging technique offering high temporal and spatial resolution, which makes it a natural choice for assessing tissue mechanical properties. We have developed methods to mechanically analyze the compliance of the rabbit trachea in vivo using tissue deformations induced by tidal breathing, offering a unique tool to assess the behavior of the airways during their normal function. Four-hundred images were acquired during tidal breathing with a custom-built endoscopic OCT system. The surface of the tissue was extracted from a set of these images via image processing algorithms, filtered with a bandpass filter set at ...
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    9. Wide tuning range wavelength-swept laser with a single SOA at 1020 nm for ultrahigh resolution Fourier-domain optical coherence tomography

      Wide tuning range wavelength-swept laser with a single SOA at 1020 nm for ultrahigh resolution Fourier-domain optical coherence tomography
      In this study, we demonstrated a wide tuning range wavelength-swept laser with a single semiconductor optical amplifier (SOA) at 1020 nm for ultrahigh resolution, Fourier-domain optical coherence tomography (UHR, FD-OCT). The wavelength-swept laser was constructed with an external line-cavity based on a Littman configuration. An optical wavelength selection filter consisted of a grating, a telescope, and a polygon scanner. Before constructing the optical wavelength selection filter, we observed that the optical power, the spectrum bandwidth, and the center wavelength of the SOA were affected by the temperature of the thermoelectric (TE) cooler in the SOA mount as well as the ...
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      Mentions: Sang-Won Lee
    10. Fourier Domain Optical Coherence Tomography for Retinal Imaging with 800-nm Swept Source: Real-time Resampling in k-domain

      Fourier Domain Optical Coherence Tomography for Retinal Imaging with 800-nm Swept Source: Real-time Resampling in k-domain
      In this study, we demonstrated Fourier-domain/swept-source optical coherence tomography (FD/SS-OCT) at a center wavelength of 800 nm for in vivo human retinal imaging. A wavelength-swept source was constructed with a semiconductor optical amplifier, a fiber Fabry-Perot tunable filter, isolators, and a fiber coupler in a ring cavity. Our swept source produced a laser output with a tuning range of 42 nm (779 to 821 nm) and an average power of 3.9 mW. The wavelength-swept speed in this configuration with bidirectionality is 2,000 axial scans per second. In addition, we suggested a modified zero-crossing method to achieve ...
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    11. Quantification of airway thickness changes in smoke-inhalation injury using in-vivo 3-D endoscopic frequency-domain optical coherence tomography

      Quantification of airway thickness changes in smoke-inhalation injury using in-vivo 3-D endoscopic frequency-domain optical coherence tomography

      Smoke inhalation injury is frequently accompanied by cyanide poisoning that may result in substantial morbidity and mortality, and methods are needed to quantitatively determine extent of airway injury. We utilized a 3-D endoscopic frequency-domain optical coherence tomography (FD-OCT) constructed with a swept-source laser to investigate morphological airway changes following smoke and cyanide exposure in rabbits. The thickness of the mucosal area between the epithelium and cartilage in the airway was measured and quantified. 3-D endoscopic FD-OCT was able to detect significant increases in the thickness of the tracheal walls of the rabbit beginning almost immediately after smoke inhalation injuries which ...

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    12. Reference spectrum extraction and fixed-pattern noise removal in optical coherence tomography

      Reference spectrum extraction and fixed-pattern noise removal in optical coherence tomography
      We present a new signal processing method that extracts the reference spectrum information from an acquired optical coherence tomography (OCT) image without a separate calibration step of reference spectrum measurement. The reference spectrum is used to remove the fixed-pattern noise that is a characteristic artifact of Fourier-domain OCT schemes. It was found that the conventional approach based on an averaged spectrum, or mean spectrum, is prone to be influenced by the high-amplitude data points whose statistical distribution is hardly randomized. Thus, the conventional mean-spectrum subtraction method cannot completely eliminate the artifact but may leave residual horizontal lines in the final ...
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    13. Semi-resonant operation of a fiber-cantilever piezotube scanner for stable optical coherence tomography endoscope imaging

      Semi-resonant operation of a fiber-cantilever piezotube scanner for stable optical coherence tomography endoscope imaging
      A forward-view optical coherence tomography (OCT) scanning catheter has been developed based on a fiber-cantilever piezotube scanner by using a semi-resonant scan strategy for a better scan performance. A compact endoscope catheter was fabricated by using a tubular piezoelectric actuator with quartered electrodes in combination with a resonant fiber cantilever. A cantilever weight was attached to the fiber cantilever to reduce the resonance frequency down to 63 Hz, well in the desirable range for Fourier-domain OCT. The resonant-cantilever scanner was driven at semi-resonance frequencies that were well out of the resonance peak but within a range of partial resonance. This ...
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    14. High-speed spectral domain polarization-sensitive optical coherence tomography using a single camera and an optical switch at 1.3 µm

      We propose high-speed spectral domain polarization-sensitive optical coherence tomography (SD-PS-OCT) using a single camera and a 1×2 optical switch at the 1.3-µm region. The PS-low coherence interferometer used in the system is constructed using free-space optics. The reflected horizontal and vertical polarization light rays are delivered via an optical switch to a single spectrometer by turns. Therefore, our system costs less to build than those that use dual spectrometers, and the processes of timing and triggering are simpler from the viewpoints of both hardware and software. Our SD-PS-OCT has a sensitivity of 101.5 dB, an axial ...

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    15. OPTICAL COHERENCE TOMOGRAPHY (WO 2009/051446)

      OPTICAL COHERENCE TOMOGRAPHY (WO 2009/051446)

      This invention relates to an optical coherence tomography, in which a light source and an optical linear beam forming system are adopted to obtain two dimensional image of high quality resolution within short time without affection by any mechanical movements. For such purpose, the optical linear beam forming system(20) comprises semicy Under lens(21), convex lens(22) and slit(23) to implement the frequency domain optical coherence tomography. Parallel light beam from the light source is incident on the surface of the semicylinder lens(21), and focal line of the semicylinder lens (21) is located in front of the ...

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    16. Axial resolution and depth range of high-resolution spectral domain optical coherence tomography at 1.3 um

      We built a high-speed, real-time spectral domain optical coherence tomography (SD-OCT) system at the 1.3 µm region using an InGaAs line-scan camera with 1024 pixels and 46.99 klines/s. In SD-OCT, the actual spatial resolution can be different from the theoretical one due to the large bandwidth of the light source and the finite number of detector pixels, especially for a long center wavelength. We calculated and compared the axial resolutions obtained from the point spread function and the physical pixel size of the OCT image. We found that the axial resolution of the SD-OCT system could be ...
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    17. Quantification of scattering changes using polarization-sensitive optical coherence tomography

      We demonstrate that changes in the degree of polarization (DOP) depend on changes in the scattering coefficient, and they can be quantified by using a polarization-sensitive optical coherence tomography (PS-OCT) system. We test our hypothesis using liquid and solid phantoms made from Intralipid suspensions and gelatin, respectively. We also quantify the DOP changes with depth caused by changes in the concentration of scatterers in the liquid and solid phantoms. It is clearly shown that the DOP change has a linear relationship with the scattering change. In our previous study, we showed that the axial slope of the DOP is different ...

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    18. Second harmonic optical coherence microscopy for functional optical imaging of biological tissues

      Chang-Keun Kim, Sang-Won Lee, Hyun-Woo Jeong et al. We constructed a second-harmonic optical coherence microscope (OCM) that combines confocal microscopy and the second-harmonic optical coherence tomography technique. This microscope provides micron or submicron resolutions in lateral direction along with coherence gating to achieve a reasonably good ... [Proc. SPIE Int. Soc. Opt. Eng. 6850, 68500Q (2008)] published Tue Feb 12, 2008.
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    19. Optical diagnosis of cervical intraepithelialneoplasm (cin) using polarization-sensitive optical coherence tomography

      Sang-Won Lee, Ji-Yeong Yoo, Jin-Ho Kang, Moon-Sik Kang, Soon-Hee Jung, Yosep Chong, Dong-Su Cha, Kyung-Hee Han, Beop-Min KimWe present a polarization-sensitive optical coherence tomography (PS-OCT) technique that can quantify the polarization changes (the degrees of circular polarization, DOCP) caused by the scattering changes induced by cervical intraepithelial neoplasia (CIN). The axial and lateral resolutions of ... [Opt. Express 16, 2709-2719 (2008)]
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    1-19 of 19
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  2. Topics in the News

    1. (19 articles) Sang-Won Lee
    2. (7 articles) Yonsei University
    3. (5 articles) UC Irvine
    4. (5 articles) Zhongping Chen
    5. (3 articles) Korea University
    6. (2 articles) Matthew Brenner
    7. (1 articles) Samsung
    8. (1 articles) Marc Rubinstein
    9. (1 articles) Brian J. F. Wong
    10. (1 articles) Gangjun Liu
    11. (1 articles) Sun Yat-Sen University
    12. (1 articles) National Institutes of Health
    13. (1 articles) University of Illinois at Urbana-Champaign
    14. (1 articles) Tianjin University
    15. (1 articles) Zhejiang University
    16. (1 articles) New York Eye and Ear Infirmary
    17. (1 articles) Eric J. Chaney
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    OPTICAL COHERENCE TOMOGRAPHY (WO 2009/051446) Semi-resonant operation of a fiber-cantilever piezotube scanner for stable optical coherence tomography endoscope imaging Reference spectrum extraction and fixed-pattern noise removal in optical coherence tomography Quantification of airway thickness changes in smoke-inhalation injury using in-vivo 3-D endoscopic frequency-domain optical coherence tomography Fourier Domain Optical Coherence Tomography for Retinal Imaging with 800-nm Swept Source: Real-time Resampling in k-domain Investigating in vivo airway wall mechanics during tidal breathing with optical coherence tomography Spectral-domain OCT with dual illumination and interlaced detection for simultaneous anterior segment and retina imaging Optical coherence tomography angiography in glaucoma Handheld optical coherence tomography for clinical assessment of dental plaque and gingiva Characterisation of macular superficial vessel density alteration in preclinical ethambutol-induced optic neuropathy using optical coherence tomography angiography Three-dimensional spatial reconstruction of coronary arteries based on fusion of intravascular optical coherence tomography and coronary angiography Dynamic-range compression and contrast enhancement in swept-source optical coherence tomography systems with a frequency gain compensation amplifier