• 한국분무공학회지
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• 제2권4호
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• pp.29-35
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• 1997

Liquid film thickness is measured by $moir\acute{e}$ topography which monitored liquid surface. $Moir\acute{e}$ fringe measurement techniques share the inherent simplicity found in optical interferometric techniques have the advantage of use over a greater range of displacement. $Moir\acute{e}$ fringe are the geometric interference patterns observed when two dense line grating are superposed. Light transmitted through a fixed line grating is deviated by the liquid film surface, producing a distored image of the grating. The $moir\acute{e}$ fringe produced by projection of this optically distored grating onto a second stationary grating permit visualization of the liquid surface and measurement of the liquid film thickness. This study measured the small amplitude of liquid film thickness to the $moir\acute{e}$ fringe pattern produced when spherical metal was dropped glycerin put)1 And the measurement of liquid film thickness flowing down an inclined plate are required to calculate the liquid slope in a position.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.500-506
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• 2014

A new 3-D reconstruction algorithm for the human face is proposed using the derivative Moir$\acute{e}$ topography which ensures fast and robust reconstruction even for rough surfaces. The Moir$\acute{e}$ interference fringe pattern is initially obtained through the projection Moir$\acute{e}$ topography based on phase shifting, and then differentiated to provide a full unwrapped phase map for a human face. $2{\pi}$ ambiguity, which has been a chronically unsolved problem with Moir$\acute{e}$ topography, is successfully surmounted by differentiating the Moir$\acute{e}$ fringe patterns both in x- and y-directions when the object is located in the x-y plane. A real human face is used for verifying the proposed derivative Moir$\acute{e}$ topography. A human face of 4 different phase-shifted images taken in the fixed plane is almost fully reconstructed in 3-D format in 0.1 mm lateral resolution.

• 반도체디스플레이기술학회지
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• 제13권1호
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• pp.83-90
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• 2014

Using a ray tracing simulation, we have investigated the moir${\acute{e}}$ and starburst phenomena of touch screen panels (TSPs) based on opaque metallic grids (square, hexagonal, and random grids). It is demonstrated that employing a random metal mesh is the most effective way to suppress the moir${\acute{e}}$ and starburst phenomena at the same time. At high crossing angles between metal mesh of TSPs and black matrix (BM) of displays, however, a random metal mesh brings in stronger moir${\acute{e}}$ phenomenon than a square metal mesh due to point defects. Though the square metal mesh suppresses the moir${\acute{e}}$ effect substantially at high crossing angles, yet it results in the strongest starburst patterns. We have also provided the simulation scheme that can capture the moir${\acute{e}}$ and starburst patterns observed experimentally and useful design guidelines for metal grids.

• 전자공학회논문지
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• 제51권1호
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• pp.152-157
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• 2014

디지털 카메라에서는 일반적으로 높은 공간주파수에 의해 발생하는 주파수 간섭을 제거하기 위해 광저대역 투과 필터(optical lowpass filter)를 사용한다. 그러나 영상을 획득할 때 광저대역 투과 필터의 사용으로 고주파 성분이 제거되어 상세 성분의 손실을 가져오게 된다. 이와 반대로, 광저대역 투과 필터를 제거한 후에 영상을 획득할 경우, 높은 공간주파수를 가지는 영역에서 moir$\acute{e}$가 발생하게 된다. 따라서, 본 논문에서는 카메라의 광저대역 투과 필터를 제거 후 영상의 상세 성분을 보존하고 moire를 제거하는 방법을 제안한다. 먼저 ISO12233 해상도 차트를 사용하여 카메라의 공간해상도(spatial frequency response)를 분석하고, 카메라의 최대 분해능에 해당하는 해상도 차트의 패턴을 모델링하여 moir$\acute{e}$가 발생하는 영역을 검출한다. 검출된 moir$\acute{e}$ 영역을 주파수 도메인에서 분석하고 DC 성분과 최대 주파수 사이의 각 주파수별 최대 값에서 발생하는 변곡점을 검출하고 변곡점에 해당하는 값을 제거하여 moir$\acute{e}$ 성분을 제거한다. 실험 결과 제안한 방법은 상세 성분의 손실을 줄이고 moir$\acute{e}$ 제거에서 우수한 성능을 보였다.

• 한국방사선학회논문지
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• 제2권4호
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• pp.5-9
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• 2008

비산란 그리드는 X선 영상에서 산란방사선을 제거시키기 위해 사용되고, 그에 따라 X선 영상의 대조도를 향상 시킬 수 있다. 그러나 많은 경우 디지털 X선 영상에서는 그리드의 부적절한 샘플링으로 인해 moir$\acute{e}$ artifact를 발생 시키게 된다. 본 논문에서는 그리드 주파수, pixel pitch, 각도와 moir$\acute{e}$ artifact의 상관관계에 관하여 분석하고 실험으로 확인하였다. 실험을 위하여 4..0 - 8.5 까지의 6가지 탄소 그리드를 사용하여 $139{\mu}m{\times}139{\mu}m$ pixel size의 DDR system에서 실험을 하였다. 본 실험을 통하여 획득한 moir$\acute{e}$ artifact의 frequency는 이론적 계산값과 거의 같았고, 특히 그리드와 detector array의 각도에 따라 moir$\acute{e}$ frequency가 달라지는 것을 확인 할 수 있었다. 본 연구를 통한 moir$\acute{e}$ artifact에 대한 이론과 data는 향후 DR system에서 moir$\acute{e}$ artifact 제거에 큰 도움을 주리라 생각한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1990-1993
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• 2003

In this paper, we propose a technique for automatic spinal deformity detection from $moir\acute{e}$ topographic images. Normally the $moir\acute{e}$ stripes show symmetry as a human body is almost symmetric. According to the progress of the deformity of a spine, asymmetry becomes larger. Numerical representation of the degree of asymmetry is therefore useful in evaluating the deformity. First, displacement of local centroids and difference of gray values are evaluated statistically between the left- and the right-hand side regions of the $moir\acute{e}$ images with respect to the extracted middle line. We classify the moire images into two categories i.e., normal and abnormal cases from the features, employing discriminant analysis. An experiment was performed employing 1,200 $moir\acute{e}$ images and 85% of the images were classified correctly.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.659-661
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• 1997

An in-plane motion measurement method using $moir{\acute{e}}$ patterns by linear-gratings and cross-gratings, which can be used as micro inertial sensors, micro actuators, and micromachined scanning microscopes is demonstrated. A simple digital image processing method that calculates and analyzes the motion of microstructure from $moir{\acute{e}}$ patterns was developed. And using several grating structures fabricated by surface micromachining, we formed $moir{\acute{e}}$ patterns and analyzed the motion of microstructure.

• 한국정밀공학회지
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• 제22권7호
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• pp.88-93
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• 2005

$Moir\acute{e}$ topography method is a well-known non-contacting 3-D measurement method. Recently, the automatic 3-D measurement by $Moir\acute{e}$ topography has been required, since the method was frequently applied to the engineering and medical fields. The 3-D measurement using projection $Moir\acute{e}$ topography is very attractive because of its high measuring speed and high sensitivity. In this paper, using two-wavelength method of projection $Moir\acute{e}$ topography was tested to measuring object with $2\pi-ambiguity$ problems. The experimental results prove that the proposed scheme is capable of finding absolute fringe orders, so that the $2\pi-ambiguity$ problems can be effectively overcome so as to treat large step discontinuities in measured objects.

• 대한기계학회논문집A
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• 제23권7호
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• pp.1129-1138
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• 1999

[$Moir\acute{e}$] technique is now being extensively investigated as a fast non-contact means of three-dimensional profile measurement especially for reverse engineering. One problem with $moir\acute{e}$ technique is so called $2\pi$-ambiguity problem that limits the maximum step height difference between two neighboring sampling points to be less than half the equivalent wavelength of $moir\acute{e}$ fringes. In this investigation, a new two-wavelength scheme of projection $moir\acute{e}$ topography is proposed and tested to cope with the $2\pi$-ambiguity problem. Experimental results are discussed to assess the new method in measuring large objects with high step discontinuities.

• 대한기계학회논문집A
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• 제32권2호
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• pp.186-193
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• 2008

[ $Moir{\acute{e}}$ ] interferometry is an optical method, providing whole field contour maps of in-plane displacements with high resolution. The demand for enhanced sensitivity in displacement measurements leads to the technique of microscopic $moir{\acute{e}}$ interferometry. The method is an extension of the $moir{\acute{e}}$ interferometry, and employs an optical microscope for the required spatial resolution. In this paper, the sensitivity of $moir{\acute{e}}$ interferometry is enhanced by an order of magnitude using an immersion interferometry and the optical/digital fringe multiplication(O/DFM) method. In fringe patterns, the contour interval represents the displacement of 52 nm per fringe order. In order to estimate the reliability and the applicability of the optical system implemented, the measurements of rigid body displacements of grating mold and the coefficient of thermal expansion(CTE) for an aluminium block are performed. The system developed is applied to the measurement of thermal deformation in a flip chip plastic ball grid array package.