• 한국광학회지
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• 제27권1호
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• pp.41-46
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• 2016

본 논문은 경면체의 3차원 형상을 측정하기 위한 광학시스템에 관한 것으로, 특히 LED 배열로 이루어진 점광원과 하프미러, 이미지센서로 구성된 비전시스템을 구성하여 광로분석을 수행하고 효과적인 근사화 방법을 제시한다. 실험을 통하여 취득된 영상 내의 점광원의 상대적 위치변화로부터 경면체의 3차원형상의 효과적 추정이 가능함을 보인다.

• International journal of advanced smart convergence
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• 제8권3호
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• pp.39-45
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• 2019

This paper presents an optical technique for the three-dimensional (3D) shape inspection of micro solder balls used in ball-grid array (BGA) packaging. The proposed technique uses an optical source composed of spatially arranged light-emitting diodes (LEDs) and the results are derived based on the specular reflection characteristics of the micro solder balls for BGA A vision system comprising a camera and LEDs is designed to capture the reflected images of multiple solder balls arranged arbitrarily on a tray and the locations of the LED point-light-source reflections in each ball are determined via image processing, for shape inspection. The proposed methodology aims to determine the presence of defects in 3D BGA shape using the statistical information of the relative positions of multiple BGA balls, which are included in the image. The presence of the BGA balls with large deviations in relative position imply the inconsistencies in their shape. Experiments were conducted to verify that the proposed method could be applied to inspection without sophisticated mechanism and productivity problem.

• 한국광학회지
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• 제14권5호
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• pp.504-508
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• 2003

최근 전자산업계에 새롭게 널리 생산되는 마이크로 전자부품들은 왜곡이 최소화된 정밀한 외관 형상을 갖도록 제조되고 관리되지만, 측정 대상의 표면이 가시광 영역에서 광산란되는 특징을 가짐으로 인해, 기존의 피죠나 마이켈슨 형태의 비교간섭법으로는 고정밀의 삼차원 형상측정이 용이하지 아니하였다. 본 논문에서는 광섬유를 이용한 새로운 개념의 점회절 간섭계를 제안하고, 이를 광산란 거친표면의 대표적인 제품인 칩패키지와 실리콘 웨이퍼의 삼차원 형상 측정에 적용하였다. 측정결과 66 mm 측정영역에서 측정 형상오차 PV(peak-to-valley value) 5.6 $\mu\textrm{m}$, 분산값($\sigma$) 1.5 $\mu\textrm{m}$를 획득함으로써 기존의 비교 간섭 측정법에 비해 더욱 향상된 측정 정밀도를 획득하였다.

• 한국광학회지
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• 제16권4호
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• pp.361-365
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• 2005

표면거칠기가 큰 가공면의 표면형상을 비접촉 고속 측정 하기 위해 고안된 점광원 절대간섭계는 점광원의 위치가 시스템 변수로 정의된다. 시스템 오차인 점광원의 위치 오차가 측정 결과에 미치는 영향을 분석하며, 이를 보정하기 위해 CCD 카메라를 이용한 보정법을 제안한다. 제안된 방법을 검증하기 위해 기준면을 측정하여 측정 정밀도의 향상을 확인하며, 이를 거친 표면형상의 특징을 가진 칩모듈 측정에 적용하였다. 측정 결과 기존의 촉침식 측정기와 $50mm{\time}50mm$의 영역에서 $9.8{\mu}m$의 측정 차이를 보임을 확인하였다.

• Current Optics and Photonics
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• 제1권2호
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• pp.107-112
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• 2017

An adaptive optics system can be simulated or analyzed to predict its closed-loop performance. However, this type of prediction based on various assumptions can occasionally produce outcomes which are far from actual experience. Thus, every adaptive optics system is desired to be tested in a closed loop on an optical test bench before its application to a telescope. In the close-loop test bench, we need an atmospheric simulator that simulates atmospheric disturbances, mostly in phase, in terms of spatial and temporal behavior. We report the development of an atmospheric turbulence simulator consisting of two point sources, a commercially available deformable mirror with a $12{\times}12$ actuator array, and two random phase plates. The simulator generates an atmospherically distorted single or binary star with varying stellar magnitudes and angular separations. We conduct a simulation of a binary star by optically combining two point sources mounted on independent precision stages. The light intensity of each source (an LED with a pin hole) is adjustable to the corresponding stellar magnitude, while its angular separation is precisely adjusted by moving the corresponding stage. First, the atmospheric phase disturbance at a single instance, i.e., a phase screen, is generated via a computer simulation based on the thin-layer Kolmogorov atmospheric model and its temporal evolution is predicted based on the frozen flow hypothesis. The deformable mirror is then continuously best-fitted to the time-sequenced phase screens based on the least square method. Similarly, we also implement another simulation by rotating two random phase plates which were manufactured to have atmospheric-disturbance-like residual aberrations. This later method is limited in its ability to simulate atmospheric disturbances, but it is easy and inexpensive to implement. With these two methods, individually or in unison, we can simulate typical atmospheric disturbances observed at the Bohyun Observatory in South Korea, which corresponds to an area from 7 to 15 cm with regard to the Fried parameter at a telescope pupil plane of 500 nm.