• 마이크로전자및패키징학회지
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• 제26권1호
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• pp.17-21
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• 2019

본 논문에서는 공작기계 등에서 필요로 하는 진직도 측정시스템을 가시광의 레이저와 CMOS 이미지센서를 사용하여 저가로 구현하였다. CMOS 이미지센서를 이용하여 광이미지를 검출하고 영상처리를 통해 진직도 변화를 계산하였다. 레이저와 이미지센서의 거리를 3m로 하여 실험한 진직도 측정에서 오차가 0.9%로 우수함을 확인하였으며, 제작된 진직도 시스템은 3D 프린터 등 다른 응용분야에서도 사용 할 수 있을 것으로 생각된다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.746-751
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• 2003

A method of measuring the length of defects on the wall of the spent nuclear fuel pool using the image processing and a laser slit beam is proposed. Since the defect monitoring camera is suspended by a crane and hinged to the crane hook, the camera viewing direction can not be adjusted to the orientation that is exactly perpendicular to the wall. Thus, the image taken by the camera, which is horizontally rotated along the axis of the camera supporting beam, is distorted and thus, the precise length can not be measured. In this paper, by using the LASER slit beam generator, the horizontally rotated angle of the camera is estimated. Once the angle is obtained, the distorted image can be easily reconstructed to the image normal to the wall. The estimation algorithm adopts a 3-dimensional coordinate transformation of the image plane where both the laser slit beam and the original image of the defects exist. The estimation equation is obtained by using the information of the beam projected on the wall and the parameters of this equation are experimentally obtained. With this algorithm, the original image of the defect taken at arbitrary rotated angle can be reconstructed to an image normal to the wall. From the result of a series of experiments, the accuracy of the defect is measured within 0.6 and 1.3 % error bound of real defect size in the air and underwater, respectively under 30 degree of the inclined angle of the laser slit beam generator. Also, the error increases as the inclined angle increases upto 60 degree. Over this angle, the defect length can not be measured since the defect image disappears. The proposed algorithm enables the accurate measurement of the defect length only by using a single camera and a laser slit beam.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.246-249
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• 2009

A compact, flexible family of UV laser material processing systems has been developed to drive advancements in both large area processing and annealing of semiconductor surfaces. UV photons can either be applied via demagnifying a mask pattern image or by scanning a homogenized excimer beam across the substrate area. 193nm, 248nm and 308nm wavelength applications are supported.

• 한국레이저가공학회지
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• 제14권2호
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• pp.24-29
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• 2011

The design of a telecentric f-${\theta}$ lens with a field of view (FOV) $30^{\circ}$ and an effective focal length of 1000mm is presented. The optical stop is placed at the front plane and the design is based on a geometric ray tracing technique, and the designed system consists of a series of convex and concave lenses. The designed f-${\theta}$ lens showed a considerable reduction in weight with a simplified structure and resulted in a good performance in the designated FOV. Detail analysis of rays is also presented. 653nm (red laser), 586nm (green laser), and 468nm (blue laser) were simulated as a light source and image illuminating source. The developed optical design requires 7 pieces of lenses made of SF1, N-FK56, N-LAK33, and BK7 glass materials. With optimal parametric design, the effective focal length was calculated to be 974.839mm which is very close to the initial design target. For the manufacturing purpose, the dimensions of lens curvature and thickness were truncated with error ranging 0.1% to 3.2%. As a result, the overall error was calculated to be 3.2% which can be still tolerable for display, laser material, and machining processing.

• Journal of Welding and Joining
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• 제33권4호
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• pp.7-16
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• 2015

New lasers such as high power, high brightness and short wavelength laser are using diverse industry. Also new technologies are developing actively to solve various issues such as spattering, process monitoring, deep penetration and key-hole stability. ICALEO is the international congress where recent technology for laser material processing and laser system are present. At 2014, it was held at San Diego in USA and more than 260 papers were presented from 28 country. The effect of the laser beam shape such as Gaussian like and top-hat was investigated on acoustic emission signal and pore formation in welding. Inline penetration depth was measured with ICI(Inline Coherent Imaging) technique and the data was verified with real time X-ray image on laser welding. The laser welding performance at low pressure environment was evaluated for the thick plate alloy steel. UV laser was used to weld various metals such as Cu, Aluminum, steel and stainless steel. The effect of the wavelength of the laser on the formation of the wave at the wall of the key-hole front and the absorptivity was investigated.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 2006년도 추계학술발표대회 논문집
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• pp.123-127
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• 2006

Hybrid type microscope with a Scanning Confocal Microscope (SCM) and a shear-force Atomic Force Microscope (AFM) is suggested and preliminarily studied. A image of $120{\times}120{\mu}m^2$ is obtained within 1 second by SCM because scan speed of a X-axis and Y-axis are 1kHz and 1Hz, respectively. Shear-force AFM is able to correctly measure the hight and width of sample with a resolution 8nm. However, the scan speed is slow and it is difficult to distinguish a surface composed of different kinds of materials. We have carried out the measurement of total image of a sample by SCM and an exact analysis of each image by shear-force AFM.

• Journal of Welding and Joining
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• 제17권3호
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• pp.71-78
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• 1999

The welded metal bellows is commonly manufactured by welding pairs of washer-shaped discs of thin sheet metal stamped from strip stock in thickness from 0.025 to 0.254 mm. The discs, or diaphragms, are formed with mating circumferential corrugations. In this study, the diaphragms were welded by using a CW Nd: YAG laser to form metal bellows. The bellows was fixed on a jig and compressed axially, while Cu-rings were installed between belows edges for intimate contact of edges. The difference between the inner diameter of bellows and jig shaft causes an eccentricity, while the tolerance between motor shaft and jig shaft causes a wobble type motion. A vision sensor which is based on the optical triangulation was used for seam tracking. An image processing algorithm which can distinguish the image by bellows edge from that by Cu-ring was developed. The geometric relationship which describes the eccentricity and wobble type motion was modeled. The seam tracking using the image processing algorithm and the geometric modeling was performed successfully.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.595-599
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• 2002

Edge welding of thin sheets is very difficult because of the fit-up problem and small weld area In laser welding, joint fit-up and penetration are critical for sound weld quality, which can be monitored by appropriate methods. Among the various monitoring systems, visual monitoring method is attractive because various kinds of weld pool information can be extracted directly. In this study, a vision sensor was adopted for the weld pool monitoring in pulsed Nd:YAG laser edge welding to monitor whether the penetration is enough and the joint fit-up is within the requirement. Pulsed Nd:YAG laser provides a series of periodic laser pulses, while the shape and brightness of the weld pool change temporally even in one pulse duration. The shutter-triggered and non-interlaced CCD camera was used to acquire a temporally changed weld pool image at the moment representing the weld status well. The information for quality monitoring can be extracted from the monitored weld pool image by an image processing algorithm. Weld pool image contains not only the information about the joint fit-up, but the penetration. The information about the joint fit-up can be extracted from the weld pool shape, and that about a penetration from the brightness. Weld pool parameters that represent the characteristics of the weld pool were selected based on the geometrical appearance and brightness profile. In order to achieve accurate prediction of the weld penetration, which is nonlinear model, neural network with the selected weld pool parameters was applied.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1069-1077
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• 2008

레이저와 카메라를 이용한 레일 마모도 측정 시스템은 정확한 마모도 측정을 위하여 레일에 조사된 레이저의 영역을 왜곡 없이 획득하고 이를 레일 단면과 정밀하게 일치시키는 과정이 매우 중요하다. 그러나 기존의 레일 마모도 측정 시스템은 빗물 등의 레일 위에 이물질이 있을 경우와 온도와 같은 측정 환경에 민감하게 반응하는 레이저의 특성으로 인하여 오차가 발생할 수 있으며 특히 외부에서 유입되는 태양광, 등과 같이 레일에 조사된 레이저와 같은 파장을 가지는 빛의 간섭에 의하여 레일에 조사된 레이저 영역 추출에 한계를 가진다. 또한, 2차원 상의 좌표 값으로 표현되는 추출된 레이저 영역을 레일단면에 맵핑시키는 과정에서 발생하는 기하학적 왜곡과 변형으로 측정 정밀도에 대한 한계가 발생하는 문제점을 가지고 있다. 본 논문에서는 레일 마모도 측정을 위하여 카메라로부터 입력되는 1메가급 해상도의 영상을 초당 480 프레임의 속도로 실시간 처리할 수 있는 DSP와 FPGA가 탑재된 고성능 영상처리보드를 개발하고 이를 기반으로 각 프레임에 대한 2D 영상 데이터를 3차원 상의 데이터로 맵핑함으로써 정밀한 레일 마모도 측정 방법을 제안하고자 한다. 획득한 영상으로부터 레일에 조사된 레이저의 영역을 정확하게 추출하기 위하여 웨이브렛 기반의 영상 알고리즘을 적용하고 2차원 상의 좌표값으로 표현된 레이저 영역을 카메라 모델과 투시 변환을 이용하여 레일의 단면에 정확하게 위치시킴으로서 ${\pm}0.5mm$ 이하의 오차범위를 가지는 고정밀 레일 마모도 측정 시스템을 개발하였다.

• 소성∙가공
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• 제19권5호
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• pp.320-324
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• 2010

Multi-Layer Ceramic Circuit(MLCC) in the face of thousands of fine pitch multi hole is processed. However, the fine pitch multi hole has a size of only a few micrometers. Therefore, in order to curtail the measurement time and reduce error, the image processing measurement method is required. So, we proposed an image processing measurement algorithm which is required to accurately measure the fine pitch multi hole. The proposed algorithm gets image of the fine pitch multi hole, extracts object from the image by morphological process, and extracts the parameters of its position and feature by edge detecting process. In addition, we have used the sub-pixel algorithm to improve accuracy. As a result, the proposed algorithm shows 97% test-retest measurement reliability within 2 ${\mu}m$. We found that the algorithm was wellsuited for measuring the fine pitch multi hole.