• Current Optics and Photonics
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• 제3권2호
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• pp.177-180
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• 2019

Based on liquid-lens technology and our previous findings on the optical model of the Chinese eye, the liquid lens is applied in the research of the crystalline-lens optical model. Theoretical models of three-layer liquid lenses are built with COMSOL software, and the effect of voltage on the shape of the interface between two liquids is analyzed. By polynomial fitting, different equations describing the interface shape are set up under different voltages. Finally, the optical system of the human eye with a three-layer liquid lens is built and analyzed with Zemax optical design software, and moreover the optical system models of emmetropia, myopia, and hyperopia are presented. This method to build a model of the human eye with a variable-focus liquid lens can provide a novel idea for more practical human-eye models for clinical regulation and control in the future.

• 한국전자통신학회논문지
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• 제5권3호
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• pp.262-268
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• 2010

본 논문은 카메라의 고정 초점방식 렌즈를 통해 얻은 영상의 왜곡을 보상하여 왜곡된 이미지 좌표에서 본래의 좌표를 갖는 원영상으로 복원하는 연구이다. 이미지 센서의 다양한 영상 기기 발달과 활용으로 다방면의 산업분야에 확대 이용되고 있으나, 카메라의 소형화와 경량화 필요로 인해 렌즈의 굴곡에 의한 수신 영상의 왜곡이 영향을 미치는 경향이 많다. 특히, 입체 영상 카메라 응용 기기인 경우 좌, 우측 렌즈의 서로 다른 왜곡으로 입체감 저하 및 좌우 이미지 왜곡 등이 수반된다. 좌, 우측 카메라 수신 영상의 각 부분별로 본래의 좌표로 환산하는 근사식을 세우고 이들을 종합하는 방식으로 접근했다. 적응 뉴로-퍼지 추론시스템을 구성하여 소속 함수를 통해 분할하고 1차 Sugeno fuzzy 모델식으로 추정하여 좌, 우측 본래의 영상에 근접한 결과를 얻었다. 이로서 저가이며 소형 렌즈를 활용한 영상으로도 정확한 입체 영상 센싱 기능과 판별을 기대할 수 있게 된다.

• Journal of the Optical Society of Korea
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• 제19권2호
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• pp.182-187
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• 2015

This paper presents a new graphical method for selecting a pair of optical glasses to simultaneously achromatize and athermalize an imaging lens made of materials in contact. An athermal glass map that plots thermal glass constant versus inverse Abbe number is derived through analysis of optical glasses and plastic materials in visible light. By introducing the equivalent Abbe number and equivalent thermal glass constant, although it is a multi-lens system, we have a simple way to visually identify possible optical materials. Applying this method to design a phone camera lens equipped with quarter inch image sensor having 8-mega pixels, the thermal defocuses over $-20^{\circ}C$ to $+60^{\circ}C$ are reduced to be much less than the depth of focus of the system.

• Current Optics and Photonics
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• 제3권5호
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• pp.429-437
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• 2019

Temperature adaptability is an important metric for evaluating the performance of an optical system. The temperature characteristics of the optical system are closely related to the material and shape of its lens. In this paper, we establish a mathematical model relating the temperature characteristics to the shape and material of the lens. Then a novel assembly structure that can solve the lens constraint and positioning problem is proposed. From those basics, the correctness of the theoretical model and the effectiveness of the assembly structure are verified through simulated analysis of the imaging quality of the optical system, whose operating temperature range is $-60{\sim}100^{\circ}C$.

• Journal of the Optical Society of Korea
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• 제19권3호
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• pp.303-310
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• 2015

An image-space telecentric lens for an intra-oral 3D scanner was designed and fabricated for dental application. Since a telecentric function can provide the same results regardless of image plane position, it helps to realize a more accurate image for an intra-oral scanner. The performance of the designed lens meets the required properties for HD resolution. In particular, lateral color is corrected within 1 pixel. This system achieves depth of focus of more than 3 mm. For user convenience, the developed system consists of a prism part and an imaging part. Both parts are optimized to reduce the front size and weight of the system. In order to make the parallax sights, parallax angle was determined to be 8 degrees between two optical systems.

• 반도체디스플레이기술학회지
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• 제8권4호
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• pp.43-48
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• 2009

The aim of this paper is to describe the development of the electron-beam optic analysis algorithm for simulating the e-beam behavior concerned with electrostatic lenses and their focal properties in the micro-column of the multi-beam lithography system. The electrostatic lens consists of an array of electrodes held at different potentials. The electrostatic lens, the so-called einzel lens, which is composed of three electrodes, is used to focus the electron beam by adjusting the voltages of the electrodes. The optics of an electron beam penetrating a region of an electric field is similar to the situation in light optics. The electron is accelerated or decelerated, and the trajectory depends on the angle of incidence with respect to the equi-potential surfaces of the field. The performance parameters, such as the working distances and the beam diameters are obtained by the computational simulations as a function of the focusing voltages of the einzel lens electrodes. Based on the developed simulation algorithm, the high performance of the micro-column can be achieved through optimized control of the einzel lens.

• Bulletin of the Korean Chemical Society
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• 제29권4호
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• pp.731-735
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• 2008

The fluid ensemble in the liquid lens, which is composed of electrolyte and silicone oil, is the key material system to vary the focal length processing of the electrochemical desorption. In order to characterize the capability of the liquid lens according to response time and optical range, we prepared a fluid ensemble comprising the electrolyte and oil. To elucidate the physical mechanism of the effective response time, we examined the viscosity dependency while satisfying the requirements for the density and refractive index of the electrolyte and oil, respectively. The characterization results indicated that the response time (up and down) is influenced by the viscosity of the electrolyte and oil. On this basis, we prepared a fluid ensemble capable of reversibly adjusting for the focal length of the liquid lens, as well as the response time. The ensemble is applicable to various systems such as micro-lens and optical sensors.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.585-589
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• 2004

This paper deals with the algorithm development that inspects defects such as Lens Focus, Black Defect, Dim Defect, Color Defect, White Balance, and Line Defect caused by the process of Compact Camera Module (CCM). These days the demand of CCM goes on increasing in various types like PDA, a cellular phone and PC camera every year. However, owing to the defect inspection of CCM by the semiskilled work the average inspection time of CCM takes about 40 to 50 seconds. As time goes by the efficiency takes a sudden turn for the worse because workers must inspect with seeing a monitor directly. In this paper, to solve these problems, we developed the imaging processing algorithm to inspect the defects in captured image of assembled CCM. The performances of the developed inspection system and its algorithm are tested on many samples. Experimental results reveal that the proposed system can focus the lens of CCM within 5s and we can recognize various types of defect of CCM modules with good accuracy and high speed.

• 한국공작기계학회논문집
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• 제15권2호
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• pp.24-29
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• 2006

The use electron-beam(E-beam) manufacturing system provides a means to alleviate optic exposure equipment's problems. We are developing an E-beam manufacturing system with scanning electron microscope(SEM) function. The E-beam manufacturing system consist of high voltage generator, beam blanker, condenser lenses, object lenses, stigmator and stage. The development of E-beam manufacturing system is used on the method of remaking SEM's structure. The functions of SEM are developed. It is important for the test of E-beam performance. In E-beam manufacturing system and SEM, beam focus is important function. In this paper, we propose intelligent remote control function for beam focus in E-beam manufacturing system. The function extends the user's function and gives convenience.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.490-495
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• 1996

Though the increment of using computer vision system in modern industry, there are lots of difficulties to measure precisely because of measurement error distortion phenomenon. Among these reasons, the distortion of edge is dominant reason which is occurred by the blurred image. The blurred image is happened when camera can not discriminate its precise focus. To calibrate and generalize distortion phenomenon is important. Thus, we must fix the discrimination criteria which is collected by image recognition of precise focus. Also, radial distortion causes an inward or outward displacement of a given image point from its ideal location. This type of distortion is mainly caused by flawed radial curvature curve of the elements. Thus, we were analyzed the distortion in terms of the changed with lens magnification.