• Korean Journal of Optics and Photonics
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• v.28 no.5
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• pp.213-220
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• 2017

This paper proposes how to fabricate an educational Mach-Zehnder interferometer that is easy to align and inexpensive, using 3D printers and semiconductor lasers. The interferometer consists of a body $165mm{\times}120mm{\times}57mm$ in size, mirror mounts, a laser holder, beam splitters, and so on. The laser path is adjusted by 4 mirror mounts, each comprised of rubber bands, small metal wires, and a screw. The interference fringe is enlarged by the lens at the final stage. The refractive index of a slide glass was measured by counting the number of moving interference fringes while the slide glass, inserted into one of the two interferometer arms, is rotating. The formula for the refractive index as a function of the optical-path difference and rotation angle was obtained, and used to calculate the refractive index of glass from the interferometer experiment. The use of a rotating glass in one arm of the interferometer nullifies the need for a precision stage, which despite its high cost is often required to observe the moving interference fringe in the classroom. Therefore, the 3D-printed Mach-Zehnder interferometer proposed in this paper can be very useful for education, because of its affordability and performance. It enables students to perform both qualitative and quantitative studies using a 3D-printed interferometer, such as measuring the refractive index of a glass sample, and the wavelength of light.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.1
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• pp.37-43
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• 2001

In this paper, we propose a new optical security technique using two phase masks based on interferometer. A binary random phase image is used as a reference image and the encrypted image is generated according to the phase difference between the reference image and the original image. If there is no phase difference of a same pixel position in two phase masks, interference intensity of the pixel has minimum value and if phase difference of a same pixel position in two phase masks is $\pi$, its interference intensity has maximum value. We can decrypt the original image by putting two phase masks on each of the two optical paths of the Mach-Zehnder interferometer. Computer simulation and the optical experiments show a good performance of the proposed optical security system.

• Korean Journal of Optics and Photonics
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• v.2 no.1
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• pp.20-25
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• 1991

Using evanescent field coupling between single ($LP_{01}$) and double ($LP_{01}, LP_{11}$) mode optical fiber, we selected LPII mode beam. With a $LP_{11}$ mode beam from a double mode fiber. we fabricated $LP_{11}$ mode fiber optic resonant ring interferometer, and assured that the guided mode is $LP_{11}$ mode from a radiation beam coming through the prism output coupler. When an external perturbation applied to the signal arm of the $LP_{11}$ fiber optic resonant ring interferometer, we examined the change of radiation mode coming from a prism output coupler and an end of optical fiber. Using two photodiode, LPn mode beam converted to voltage. This two output voltages is applied to X and Y terminal of oscilloscope to display circular motion on oscilloscope.

• Journal of the Korea Computer Graphics Society
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• v.16 no.1
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• pp.9-20
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• 2010

In order to visualize participating media in 3D space, they usually calculate the incoming radiance by subdividing the ray path into small subintervals, and accumulating their respective light energy due to direct illumination, scattering, absorption, and emission. Among these light phenomena, scattering behaves in very complicated manner in 3D space, often requiring a great deal of simulation efforts. To effectively simulate the light scattering effect, several approximation techniques have been proposed. Volume photon mapping takes a simple approach where the light scattering phenomenon is represented in volume photon map through a stochastic simulation, and the stored information is explored in the rendering stage. While effective, this method has a problem that the number of necessary photons increases very fast when a higher variance reduction is needed. In an attempt to resolve such problem, we propose a different approach for rendering particle-based volume data where kernel smoothing, one of several density estimation methods, is explored to represent and reconstruct the light in-scattering effect. The effectiveness of the presented technique is demonstrated with several examples of volume data.

• Polymer(Korea)
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• v.37 no.5
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• pp.656-662
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• 2013

The flexible patterned cover film was made by a simple solution coating process using polymethyl methacrylate (PMMA) solution with glass beads. The effect of patterned cover film on the efficiency of solar cell has been investigated. It was found that the relative solar cell efficiency increased up to 3.4% with the incident light angle between $0-90^{\circ}$ by the sphere shape of glass bead coated on the film surface. This was understood that the loss of transmittance and scattering due to the light directional dependency on solar cell were minimized because the light entered glass beads normal to its surface regardless of incident light angle. The maximum relative solar cell efficiency was achieved when glass bead shape on the film is hemisphere and the relative efficiency increased with increasing the amount of glass bead on the film surface. However, too much glass beads on the film surface resulted in the lower relative solar cell efficiency due to the lowering of transmittance as well as the occurring of light interference.

• Journal of the Korean Magnetics Society
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• v.4 no.4
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• pp.307-312
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• 1994

The magneto-optical Kerr effect due to the (Fe,Co)/(Pd,Pt,Cu,Ag) multilayer film is calculated considering of multiple reflection effect, and the calculated Kerr spectrum is compared to the reported experimental value. In case of Co/Pd, the reliance of composition and the variable tendency of magneto-optical Kerr rotation angle for Co thickness fully coresponds to experimantal and theoretical value. The theoretical Kerr spectrum of Fe/Cu and Fe/Ag multilayer films show the peaks near the Cu and Ag optical ansorption band in accordance with the experiment. But in case of Co/Pt, the increase tendency of Kerr rofation with decreasing wavelength reported by experiments could not be explained by the optical multiple interference. This difference of theoretical and experimental Kerr spectrum of Co/Pt film might be related with the change of electronic structure of Co and/or Pt from their bulk state.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.76-92
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• 2016

산업이 고도화될수록 높은 품질과 보다 정밀하게 가공된 제품의 안정된 생산이 요구되고 있으며, 그에 대한 표준화된 측정법 및 관리법이 요구되고 있다. 산업체에서 생산되는 다양한 형태의 제품들 중, 마이크로메타 또는 나노메타 수준의 정밀한 가공 및 측정에 있어서, 정확하고 일관성 있게 빠른 시간 안에 제품분석을 수행 할 수 있는 방법은 오래 전부터 활발히 연구되고 있으며, 그 중 광학 기반의 3D-profiler 는 빠른 속도와 간편한 사용으로 많은 인기를 얻고 있다. 이러한 분석법은 광학 현미경의 평면 분해능을 가지고, 나노크기의 물체 높이를 판별하여, 측정된 정보를 3차원 이미지로 형태를 재 구성할 수 있어, 미세한 표면 조도 변화나 나노 수준의 패턴 단차에 대한 정보를 간단하게 얻을 수 있다. 또한 빛의 간섭현상에 기초하여 시료 표면에 대한 정보를 얻기 때문에 원자단위 이하 수준의 측정 해상도를 가지게 된다. 표면의 칼라패턴에 대해서도 2D 평면 정보를 기초로, 다양한 색상의 패턴들에 대해 각각의 색에 따른 정확한 높이 분석 및 그 패턴 분리, 색깔과 매칭되는 3D 이미지 구현 등과 같은 분석이 가능하여, 이를 활용하여 다양한 분야에서 활발히 사용되고 있다. 실제 현장에서 측정된 다양한 3D 이미지를 소개하며, 이를 통해 광학 3D-Profiler에 대한 전반적인 성능 소개와 그 이해를 돕고자 한다.

• Korean Journal of Optics and Photonics
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• v.8 no.1
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• pp.26-30
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• 1997

A wide dynamic range heterodyne interferometer scheme using intermode beat between a stabilized, dual frequency He-Ne laser beam has been applied for a measurement of optical thickness of an optical medium. Resolution of the optical thickness measurement is about $\pm$ 1.74 ${\mu}{\textrm}{m}$. Using this technique, we are able to determine the optical thickness of an organic dye film. We also obtain a map of the optical thickness variations over a surface of the film

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.1
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• pp.83-90
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• 2019

LED lighting is spreading on the strength of LED lighting, and various government policies are being implemented. VLC research which is a wireless communication technology using lighting has been actively conducted, and it has been proven through many studies that a general LED light source such as a high-speed data transmitter can be used. But from now on, one of the main problems is the noise from side lights, which can be compared to the noise of radio broadcasts. So in this paper, we proposed a noise canceling model to remove the interference of ambient light by using an optical filter for a detachable VLC channel. In order to verify the proposed model, various high brightness RGB LED modules were used for comparative analysis. In addition, the applicability was verified through experiments using High Luminance LED lighting which is applied in real life.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.2
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• pp.122-127
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• 2001

The high stability of the interference pattern is very important in the case of measuring interference when a phase noise like a vibration occurs in the measuring environment. In this paper, we proposed the method of phase noise filtering by BaTiO$_3$ with the characteristic of SPPCM. Also, a beam with a shape of an ellipse was incident into BaTiO$_3$ by using the tilted lens so as to improve the reflectivity and the response time. And we confirmed the result by optical experiment.