• Journal of the Optical Society of Korea
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• v.19 no.1
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• pp.69-73
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• 2015

The mesothelium is an essential lining for maintaining the normal homeostasis of the closed body cavity and a central component of pathophysiologic processes. The mesothelium has been known as the end target for asbestos which induces asbestos-related lung diseases. Malignant mesothelioma (MM) is a rare and fatal neoplasm predominantly due to asbestos exposure. Adaptation of an advanced and reliable technology is necessary for early detection of MM because it is difficult to diagnose this disease in its early stages. Optical coherence tomography (OCT) provides cross-sectional images of micro-tissue structures with a resolution of $2-10{\mu}m$ that can image the mesothelium with a thickness of ${\sim}100{\mu}m$ and, therefore, enable investigation of early development of MM. The mesothelium is typically located at the pleura and tunica vaginalis of the scrotum. In this study, we developed animal window models in the above two anatomical sites to visualize mesothelial layers within the mesothelium. OCT images at the two locations were also acquired.

• Journal of the Optical Society of Korea
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• v.19 no.1
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• pp.55-62
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• 2015

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 $26.07^{\circ}$, in combination with a lens of focal length 85.1 mm, are suitable for UHR SD-OCT with the imaging depth range (limited by spectrometer resolution) set at 2.0 mm. As guided by the simulation results, we constructed the linear-k spectrometer needed to implement a UHR SD-OCT. The actual imaging depth range was measured to be approximately 2.1 mm, and axial resolution of $3.8{\mu}m$ in air was achieved, corresponding to $2.8{\mu}m$ in tissue (n = 1.35). The sensitivity was -91 dB with -10 dB roll-off at 1.5 mm depth. We demonstrated a 128.2 fps acquisition rate for OCT images with 800 lines/frame, by taking advantage of NVIDIA's compute unified device architecture (CUDA) technology, which allowed for real-time signal processing compatible with the speed of the spectrometer's data acquisition.

• Journal of the Optical Society of Korea
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• v.16 no.2
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• pp.174-180
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• 2012

In this study, the feasibility of spectral domain optical Doppler tomography for measuring blood flow characteristics in a micro-tube was demonstrated through several experiments. The use of an SD-ODT system in blood flow measurement can provide high resolution images (5 microns resolution). We prepared three capillary tubes to reveal the effect of different concentrations of hematocrit ratio (HR). One tube serves as the control. The two other tubes contained different concentrations of HR (5%, 25%). Three different capillary tube inlet flow velocities were tested in the present study. The Reynolds number (Re) which is based on the capillary tube inner diameter ranges from Re=6 to 48. We calculated a Doppler shift of the power spectrum of the temporal interference fringes with Kasai autocorrelation function to achieve the velocity profile of the flow. As a result, SD-ODT systems could not detect the cell depletion layer in the present study due to the limitation of spatial resolution. Nevertheless, these systems were proven to be capable of observing the RBCs of blood.

• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.55-59
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• 2014

Sarcopenia, or reduced muscle mass and volume, is due to various factors such as senile change, neuronal degeneration, drug, malignancy, and sepsis. Sarcopenia with the aging process has been evidenced by the decline in muscle mass by 0.5 to 1% per year with 3-5% reduction in muscle strength for 10 years between the ages of 40 and 50, and a 1-2% of decline of mass every year in people aged 60-70. Therefore, early diagnosis and understanding the mechanism of sarcopenia are crucial in the prevention of muscle loss. However, it is still difficult to image changes of muscle microstructure due to a lack of techniques. In this study, we developed an animal model using denervated rats to induce a rapid atrophy in the tibialis anterior (TA) and imaged its structural changes using optical coherence tomography (OCT) along with histologic and ultrasound analyses. Ultrasound showed changes of overall muscle size. Histology revealed that the atrophic TA muscle displayed an increased size variability of muscle fiber and inflammatory changes. Three dimensional OCT imaged the changes of perimysial grid and muscle fiber structure in real time without sacrifice. These observed advantages of multimodal imaging using OCT and ultrasound would provide clinical benefits in the diagnosis of sarcopenia.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.126-131
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• 2004

As a noninvasive imaging method, optical coherence tomography system has been extensively studied because it has some advantages such as imaging of high resolution, low cost, and compact size configuration. In order to improve the SNR of OCT system, two types of interferometers were configured and then, we compared simulation with measurement of reference sample. In the OCT system is configured with Michelson interferometer, the contrast of cross-sectional image is reduced with low SNR detection which is due to loss of feedback interference signal from light source part. Also, in order to image measured data with real time, image processing program is constructed. From results of simulation, it is confirmed that improved Michelson interferometer is improved about 10[dB] with a 50 : 50 fiber coupler. And from the measurement of reference sample, about 5[dB] is improved with a 50 : 50 fiber coupler. It is confirmed that the OCT system is configured with the improved Michelson interferometer which has a good distinctive cross-sectional image due to higher contrast.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.274-275
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• 2003

광통신 분야의 연구 중 근거리 광통신 분야에 적용하기 위한 Plastic Optical Fiber(POF)에 관한 연구와 개발이 활발히 이루어지고 있다. POF의 광전송 특성을 결정짓는 요소 중 가장 중요한 특성이 바로 굴절률 분포이다. 이에 따라 그동안 다양한 형태의 POF 굴절률 측정 방법이 연구되어 왔다. 기존 Glass Optical Fiber의 굴절률 분포 측정 방법 중 가장 일반적이고 효과적인 방법 중 하나는 coherent 빛의 간섭을 이용한 transverse interferograms을 분석하는 방법으로 Fizeau 간섭계와 같은 간섭계를 이용하여 위상변화를 측정하고 측정한 위상을 tomography적인 해석방법을 통해 굴절률 분포를 계산하는 방법이다. (중략)

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.3
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• pp.299-304
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• 2021

Purpose. The purpose of the present study was to investigate the effects of image matching experience of operators on the accuracy and working time of image registration between radiographic and optical scan images. Materials and methods. Computed tomography and optical scan of a dentate dental arch were obtained. Image matching between the computed tomography and the optical scan (IDC S1, Amann Girrbach, Koblah, Austria) was performed using the point-based automatic registration method in planning software programs (Implant Studio, 3Shape, Copenhagen, Denmark) using two different experience conditions on image registration: experienced group and inexperienced group (n = 15 per group, N = 30). The accuracy of image registration in each group was evaluated by measuring linear discrepancies between matched images, and working time was recorded. Independent t test was used to statistically analyze the result data (α = .05). Results. In the linear deviation, no statistically significant difference was found between the experienced and inexperienced groups. Meanwhile, the working time for image registration was significantly shorter in the experienced group than in the inexperienced group (P = .007). Conclusion. Difference in the image matching experience may not influence the accuracy of image registration of optical scan to computed tomography when the point-based automatic registration was used, but affect the working time for the image registration.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.711-712
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• 2008

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.69-70
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• 2007

• The Magazine of the IEIE
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• v.41 no.2
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• pp.44-48
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• 2014