• 한국레이저가공학회지
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• 제18권1호
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• pp.18-22
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• 2015

In this paper, controlling shape of optical fiber tip for endoscope was investigated for eliminating blind spot. The blind spot of endoscope is generated by divergence angle of optical fiber, so it is easy to generate blind spot when tightly focusing. In order to eliminate this region, fiber tip is necessary to be controlled as convex or concave. Illumination simulation of convex and concave type of fiber tip in the endoscope was in progress, so the distance of non- blind region was investigated in each case. As well as the simulation, the tip was fabricated as concave shape by UV laser machining. Then the beam radiation was measured to observe the blind region. The result showed that controlling the fiber tip as convex or concave shape makes the narrow blind region of illumination in endoscope.

• 대한의용생체공학회:의공학회지
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• 제30권3호
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• pp.263-269
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• 2009

An object's color and intensity are determined by its spectral reflectance and illumination. Therefore, the illumination plays a key role in forming the appearance of the object in a scene. In this paper, we focus on color distinction of objects and derive the optimal illumination conditions to maximize the distance between objects in the RGB color space. As a practical approach the optimal illumination is composed by deriving the optimal linear combinations given a set of LED light sources. The effectiveness of our approach is shown through experimental results using an endoscope system.

• Current Optics and Photonics
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• 제7권6호
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• pp.755-760
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• 2023

In this paper, an illumination optical system that can mitigate the saturation phenomenon in the center of an image (caused by the typical flexible-endoscope illumination system using LEDs with Lambertian light distribution) is designed. When an LED with Lambertian light distribution is used as a light source, the amount of light in the center of the endoscopic illumination system is relatively high, compared to the periphery, causing saturation in the image. Since this phenomenon causes difficulty in detecting the patient's lesion, it is necessary to find a lighting-system design that can alleviate the saturation phenomenon. Therefore, in this paper a lighting system with bat-wing light distribution, which can lower the intensity at the center and secure the maximum amount of light at the maximum light distribution angle, is designed. In addition, to check the performance of the designed lighting system, a simulation of illumination and luminance is conducted for a system using a common aspherical lens with otherwise the same components. As a result, it is confirmed that the lighting system designed in this paper effectively reduces the luminance value at the center and secures more luminance values at the periphery than the familiar lighting system.

• 한국광학회지
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• 제32권2호
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• pp.68-78
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• 2021

측면 360° 조명을 위한 6개의 LED (light emitting diode)로 구성된 조명계가 부착된 캡슐내시경용 초소형 반사굴절식 전방위 광학계를 설계하고 성능을 평가하였다. 이 광학계의 총 길이, 전장길이, 반화각(HFOV: half field of view), F-수는 각각 14.3 mm, 8.93 mm, 51°~120°, 3.5로 설계되었다. 이 전방위 광학계는 0.1 megapixels의 CMOS (complementary metal-oxide-semiconductor) 센서를 사용하였으며, LED 조명계는 한 개당 0.25 lm의 LED 6개를 사용하여 광축을 따라 놓여 있는 내장의 내벽을 조명하도록 하였다. 이 결과, 최적화 설계된 광학계의 변조전달함수 0.3에서의 공간주파수, 나이퀴스트 주파수인 44 lp/mm와 0.3의 변조전달함수에서 공차에 따른 누적확률, 초점심도는 각각 130 lp/mm, 95%, -0.097 mm~+0.076 mm이다. 또한 광학계의 시야각 범위 내에서 LED 조명계에 의한 광축으로부터 물체거리가 15 mm인 내장의 내벽에서의 시뮬레이션된 조도는 최소 315 lx~최대 725 lx로 내장의 내벽을 촬영할 수 있는 조도와 가시도임을 알 수 있다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1158-1159
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• 2009

Tri-stimulus values of CIE-XYZ and RGB values obtained by photographic film, CCD camera or scanner depend on the spectral sensitivity of imaging devices and the spectral radiant distribution of the illumination. It is important to record and reproduce the reflectance spectra of the object for true device independent color reproduction and high accurate recording of the scene. In this paper, a method to record the reflection spectra of the object is introduced and its application to spectral endoscopes is presented.