• Journal of ILASS-Korea
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• v.2 no.4
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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 Korean Society for Precision Engineering
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• v.22 no.7 s.172
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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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.7 s.166
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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.

• Proceedings of the KIEE Conference
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• 1997.11a
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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.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.11a
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• pp.49-53
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• 2009

미래병사를 위한 전투지원 시스템은 여러 가지 디지털 디바이스로 구성되며, 이러한 디바이스들을 적절한 위치에 분산시킴으로써 병사의 전투력을 향상시킬 수 있도록 설계하는 것이 중요하다. 분산 디자인을 위해서는 동작에 따른 인체의 변화를 측정하는 것이 중요하며, 특히 센서를 탑재하기 위해서는 인체 표면의 변화가 세밀히 분석되어야 할 것이다. 본 연구는 Moir$\acute{e}$ 계측방법을 이용하여 동작에 따른 체표변화를 측정함으로써 각종 디지털 디바이스를 탑재할 적절한 신체 부위를 알아내어 기기를 배치함으로써 미래 전장에 적합한 스마트 전투복 디자인을 개발하는 것을 목표로 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.2
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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.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.1
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• pp.57-65
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• 2017

The electronic components in mobile device are composed of electronic chips and various other materials. These components become extremely thin and the constituent materials have different coefficient of thermal expansion, so that considerable warpages occurs easily due to temperature change or external load. Shadow $moir{\acute{e}}$ is non-contact, whole field technique for measuring out-of-plane displacement, but the measurement sensitivity is not less than $50{\mu}m/fringe$, which is not suitable for measuring the warpage of the electronic components. In this paper, we implemented a measurement method with enhanced sensitivity of $25{\mu}m/fringe$ by investigating and optimizing various experimental conditions of the shadow $moir{\acute{e}}$. In addition, four $moir{\acute{e}}$ fringe patterns recorded by the phase shift are processes to obtain a $moir{\acute{e}}$ fringe patterns with a sensitivity four times higher. The measurement technique is applied to small electronic components of a smart phone for measuring warpage with a high sensitivity of $5{\mu}m/fringe$ at room temperature and at the temperature of $100^{\circ}C$.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.3
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• pp.57-65
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• 2015

Electronic packages consist of various materials, and as temperature changes, warpage occurs because of the difference in coefficient of thermal expansion. Shadow $moir{\acute{e}}$ is non-contact, whole field measurement technique for out-of-plane displacement. However, the technique has low sensitivity above $50{\mu}m/fringe$, it is not adequate for the warpage measurement in some circumstance. In this paper, by applying phase shifting process to the traditional shadow $moir{\acute{e}}$, measurement system having enhanced sensitivity of $12.5{\mu}m/fringe$ is constructed. Considering Talbot effect, the measurement is carried out in the half Talbot area. Shadow fringe pattern having four times enhanced sensitivity is obtained by the image process with four shadow fringes. The measurement technique is applied to the fibered package substrate and coreless package substrate for measuring warpages at room temperature and at about $100^{\circ}C$.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.181-186
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• 2000

The setup of the moir$\acute{e}$ deflectometry using the virtual grating was done, so the convergence and divergence of a pencil of ray was determined. The light source was He-Ne laser(3mW). The focal length of the first lens, the second lens being 18 mm, 250 mm respectively was used for the setup of the beam expander. The optics of the moir$\acute{e}$ deflectometry determining the vergence was used a diffraction grating(pitch = $1.6{\mu}m/line$) and a front flat reflection mirror. The effective focal length of the trial lens set was measured and compared with the theoretical value.

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.126-127
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• 1999