1. Articles from Eun Seo Choi

    1-11 of 11
    1. Spectral Domain Optical Coherence Tomography Imaging Performance Improvement Based on Field Curvature Aberration-Corrected Spectrometer

      Spectral Domain Optical Coherence Tomography Imaging Performance Improvement Based on Field Curvature Aberration-Corrected Spectrometer

      We designed and fabricated a telecentric f-theta imaging lens (TFL) to improve the imaging performance of spectral domain optical coherence tomography (SD-OCT). By tailoring the field curvature aberration of the TFL, the flattened focal surface was well matched to the detector plane. Simulation results showed that the spot in the focal plane fitted well within a single pixel and the modulation transfer function at high spatial frequencies showed higher values compared with those of an achromatic doublet imaging lens, which are commonly used in SD-OCT spectrometers. The spectrometer using the TFL had an axial resolution of 7.8 m, which ...

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    2. VCSEL-based swept source for low-cost optical coherence tomography

      VCSEL-based swept source for low-cost optical coherence tomography

      We present a novel wavelength-swept laser source for optical coherence tomography (OCT) which is based on the conventional laser diode technology of the verticalcavity surface-emitting laser (VCSEL). In our self-heating sweep VCSEL (SS-VCSEL), a VCSEL device is simply driven by ramped pulses of currents in direct intensity modulation. The intrinsic property of VCSEL produces a frequency-swept output through the self-heating effect. By the injected current, the temperature of the active region is gradually increased in this effect. Consequently, it changes the wavelength of the laser output by itself. In this study, various characteristics of our SS-VCSEL were experimentally investigated for ...

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    3. Optical coherence tomography application by using optical phase shift based on fiber optic sensor

      Optical coherence tomography application by using optical phase shift based on fiber optic sensor

      We demonstrate fiber-optic sensor applications to full-range complex optical coherence tomography (OCT). To extend imaging range in OCT, real value or interferogram measured from an interferometer is needed to convert into complex value. For the purpose, various treatments such as mechanical, electro-optical, optical and programming based methods have been exploited in the interferometer. To make complex signal in fiber-optic interferometer, we propose vibrationbased optical phase shifting method. The proposed method utilizes optical fiber sensors that are for the detection of vibration using optical fiber. When coiled fiber was exposed to vibration, interferogram presents fringe shift without periodicity variations, which means ...

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    4. Full-field optical coherence tomography system implemented with fiber-optic components

      Full-field optical coherence tomography system implemented with fiber-optic components

      We have presented full-field optical coherence tomography(FF-OCT) system implemented with fiber optics. Usually FFOCT system illuminates large area at once while conventional OCT system irradiates light at single focal point. From these reason, light guidance with single fiber waveguide is not proper in FF-OCT system and fiber-optic components is not dealt in the system implementation. In this paper, we demonstrate FF-OCT system implemented with fiber-optics, where fiber coupler and fiber-optic circulator were used to perform the function of beam splitting and optical delay line. Each arm of fiber coupler acts as reference arm and sample arm. Fiber-optic collimator and ...

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    5. Feasibility of Full-field Optical Coherence Microscopy in Ultra-structural Imaging of Human Colon Tissues

      Feasibility of Full-field Optical Coherence Microscopy in Ultra-structural Imaging of Human Colon Tissues
      We demonstrated imaging feasibility of full-field optical coherence microscopy (FF-OCM) in pathological diagnosis of human colon tissues. FF-OCM images enabling high transverse resolution were obtained at different depth of the samples without any dye staining and physical slicing and visualized detailed microstructure of the human colon tissues. Morphological differences in normal tissues, cancer tissues and tissues under transition state were observed and matched with results seen in conventional optical microscope images. The optical biopsy based on FF-OCM could overcome the limitations on the number of physical cutting of tissues and perform high-throughput mass diagnosis of diseased tissues. The proved utility ...
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    6. Ultrawideband photonic crystal fiber coupler for multiband optical imaging system

      Ultrawideband photonic crystal fiber coupler for multiband optical imaging system
      We report a photonic crystal fiber (PCF) coupler having an ultrawide spectral bandwidth keeping single mode operation. The use of the PCF coupler in a fiber-based optical coherence tomography (OCT) system enables us to handle the wide spectral bands of various light sources, including superluminescent diodes (SLDs) at 1300 nm and 820 nm, Ti:sapphire lasers, and white-light sources. The multiband imaging performances of the PCF-based OCT system are demonstrated by obtaining dental images at 1300 nm and 820 nm with the same setup. In addition, we show that the PCF coupler could cover the spectrum over a one octave ...
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    7. Thickness and index measurements of a transparent specimen by full-field optical coherence microscopy

      We present the method measuring the thickness and the refractive index of a transparent specimen at a same time based on full-field optical coherence tomography. As a sample a small drop of epoxy was placed on a flat plate and the high-resolution depth resolved en-face images of the epoxy drop were taken. With adopting the plate surface as a reference plane, the physical thickness and the refractive index distribution could be obtained. Owing to the full-field imaging capability, we could obtain the transverse distributions of the thickness and the refractive index without any transverse scanning. The measured thickness at the ...
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    8. Simultaneous measurements of optical coherence tomography and fluorescence spectroscopy based on double clad fiber

      We report an all-fiber system aided by double-clad fiber (DCF) and DCF devices for simultaneous measurements of optical coherence tomography (OCT) and fluorescence spectroscopy (FS). The DCF together with DCF coupler and single-body DCF lens helped in realizing a ultifunctional single-unit probe fo ... [Proc. SPIE 7171, 71710T (2009)] published Fri Feb 20, 2009.
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    9. Combined system of optical coherence tomography and fluorescence spectroscopy based on double-cladding fiber

      We report the development of an all-fiber multimodal system, based on a double-cladding fiber (DCF) and related devices, suitable for simultaneous measurements of optical coherence tomography (OCT) and fluorescence spectroscopy (FS). The DCF together with a DCF coupler and a single-body DCF lens ... [Opt. Lett. 33, 2347-2349 (2008)]
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    10. Optical approach for monitoring the periodontal ligament changes induced by orthodontic forces around maxillary anterior teeth of white rats

      Optical approach for monitoring the periodontal ligament changes induced by orthodontic forces around maxillary anterior teeth of white rats
      Abstract  Structural variations of the periodontal ligament (PDL) induced by orthodontic forces have been evaluated by optical coherence tomography (OCT) and compared to images obtained by conventional radiography. Here, two specially designed orthodontic appliances were installed on the maxillary anterior teeth of white rats for applying different magnitudes of orthodontic forces. Constant distraction force magnitudes of 0, 5, 10, and 30 gf were given to four respective rats over a period of 5 days. At the end of the treatment period, the rats were sacrificed and the maxillaries were extracted for X-ray and OCT imaging. The PDL variations, proportional to ...
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    11. Image restoration method based on Hilbert transform for full-field optical coherence tomography

      A full-field optical coherence tomography (FF-OCT) system utilizing a simple but novel image restoration method suitable for a high-speed system is demonstrated. An en-face image is retrieved from only two phase-shifted interference fringe images through using the mathematical Hilbert transform. ... [Appl. Opt. 47, 459-466 (2008)]
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    1-11 of 11
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  2. Topics in the News

    1. (8 articles) Gwangju Institute of Science and Technology
    2. (6 articles) Seon Young Ryu
    3. (6 articles) Byeong Ha Lee
    4. (5 articles) Jihoon Na
    5. (4 articles) Hae Young Choi
    6. (3 articles) Woo June Choi
    7. (1 articles) UC Irvine
    8. (1 articles) University of Ulsan
    9. (1 articles) Zhongping Chen
    10. (1 articles) Tae Joong Eom
    11. (1 articles) Yamagata University
    12. (1 articles) Bern University of Applied Sciences
    13. (1 articles) Medical University of Vienna
    14. (1 articles) University of Maryland
    15. (1 articles) Koen A. Vermeer
    16. (1 articles) Vishali Gupta
    17. (1 articles) Bernhard Baumann
    18. (1 articles) Brandon J. Lujan
    19. (1 articles) Antonia Lichtenegger
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    Optical approach for monitoring the periodontal ligament changes induced by orthodontic forces around maxillary anterior teeth of white rats Ultrawideband photonic crystal fiber coupler for multiband optical imaging system Feasibility of Full-field Optical Coherence Microscopy in Ultra-structural Imaging of Human Colon Tissues Full-field optical coherence tomography system implemented with fiber-optic components Optical coherence tomography application by using optical phase shift based on fiber optic sensor VCSEL-based swept source for low-cost optical coherence tomography Hybrid registration of retinal fluorescein angiography and optical coherence tomography images of patients with diabetic retinopathy Optical Coherence Tomography Angiography Quality Across Three Multicenter Clinical Studies of Diabetic Retinopathy The Role of Optical Coherence Tomography Angiography(OCTA) in Detecting Choroidal Neovascularization in DifferentStages of Best Macular Dystrophy: A Case Series Discrimination of diabetic retinopathy from optical coherence tomography angiography images using machine learning methods Quantitative analysis of vascular changes during photoimmunotherapy using speckle variance optical coherence tomography (SV-OCT) High-resolution, depth-resolved vascular leakage measurements using contrast-enhanced, correlation-gated optical coherence tomography in mice