• Korean Journal of Optics and Photonics
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• v.10 no.2
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• pp.102-106
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• 1999

In this study, inhomogeneous amplitude modulation effects on the imaging performance a lens system are expermentally investigated by measuring the diffraction OTF. The lens under the test is a binocular objective made in Korea. Inhomogeneous amplitude modulation is carried out by positioning the modulator cross contacted to the lens under test which is illuminated by collimated light beam. The aberration characteristics of the lens under test are examined by caculating the ray-fan through finite ray tracing. The MTFs of the lens illuminated by the homogeneous and inhomogeneous light beam are measured on the Gaussian image plane and compared with one another.

• Korean Journal of Optics and Photonics
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• v.8 no.1
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• pp.19-25
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• 1997

Holographic zone plate (HZP) is fabricated by interfering a plane wave and a spherical wave in a dichromated gelatin (DCG) film obtained from Agfa 8E75HD plates. We have developed a simple theory for HZP considering optical nonlinearity of DCG material. Analysis of our theory for HZP shows that it has infinite focal points at distances f,f/2, f/3,,…. In experiment, we observed the corresponding focal points of up to f/6 when illuminating HZP by a plane wave. It is also shown that the beam profile around the first focal point measured by using a knife-edge scanning method has a Gaussian shape.

• Current Optics and Photonics
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• v.1 no.4
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• pp.271-277
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• 2017

Based on the extended Huygens-Fresnel principle, the analytical propagation formulae for spectrally partially coherent Gaussian Schell-model pulsed (SPGSMP) beams propagating in turbulent atmosphere have been derived. The influences of the parameters for turbulent atmosphere and SPGSMP beams on the on-axis and off-axis spectral shift and degree of coherence for SPGSMP beams propagating in turbulent atmosphere have been analyzed, using numerical calculations. The obtained results have potential applications for SPGSMP beams in free-space optical communication and laser lidar.

• Journal of the Korea Society of Computer and Information
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• v.21 no.12
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• pp.27-33
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• 2016

In this paper, we propose the bilateral filter based on median value that can reduce random noise and impulse noise with minimal loss of contour information. In general, EO / IR camera to generate a random or impulse noise due to a number of reasons. This noise reduces the performance of detecting and tracking by signal processing. To reduce noise, our proposed bilateral filter sorts the values of the target pixel and the peripheral pixels, and extracts a median filter coefficients of the Gaussian type. Then to extract the Gaussian filter coefficient involved with the distance between the center pixel and the surrounding pixels. As using those filter coefficients, our proposed method can remove the various noise effectively while minimizing the loss of the contour information. To validate our proposed method, we present experimental results for several IR images.

• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.95-98
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• 1997

The Gaussian diffraction pattern initially assumed in the diffraction inverse problem is further sharply defined by multiplying $e^{-q{\omega}_0$\mid${\chi}$\mid$}$. The modified pupil function is obtained and the diffraction intensity distribution for the finite aperture ($-{\omega}_0~{\times}{\omega}_0$ is obtained, and then the OTF is derived analytically. It is found the OTF is equal to or less than the $(OTF)_{q=0}$, namely the modulation is not useful. It is shown that the narrowing down the initial Gaussian diffraction pattern does not give the anticipated improvement in OTF and the reason is clarified.

• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.80-83
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• 2008

Optical tweezers are a tool that can use a tightly focused laser beam to trap and manipulate micron-sized dielectric particles that are immersed in a medium with lower refractive index. In this paper, the calculation of the trapping force of optical tweezers is presented. A nonparaxial Gaussian beam is used to represent a tightly focused Gaussian beam, and the FDTD (Finite-Difference Time-Domain) method is used for computing the electromagnetic field distributions in the dielectric medium. Scattered-field formulation is used for analytical expression of the incident fields. Using the electromagnetic field distribution from FDTD simulation, the trapping force is calculated based on Maxwell's stress tensor.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.207-209
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• 2006

This study is about an effect on a characteristics of the laser heat treatment as a optic systems which have a transverse beam mode each other. An experiment are carried out using a circular gaussian beam optics and rectangular beam optics. Generally, the optic system which has a uniform power intensity is mainly used in the laser heat treatment process. In this study, we would like to carried out experiments simultaneously using two optic systems and research the differences from a characteristics of the laser heat treatment.

• Journal of the Optical Society of Korea
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• v.10 no.4
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• pp.188-195
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• 2006

Third harmonic generation microscopy is described in the frame work of the theory of harmonic generation with Gaussian focused beams inside a bulk material as well as at the vicinity of an interface. This model is then applied to characterize different types of materials in terms of electronic third-order susceptibility. Examples of bulk glasses, poled glasses, laser-induced modifications in glasses and nanoparticles in solution are given in order to give a survey of the broad application field of THG microscopy in material characterization.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.5-9
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• 2000

The visual evoked potential was electrophysiological method for the identify of the EEG response on visual cortex. This test was objective test method on the eye function. This study was used the visual evoked potential for the objective color test. The subjects was a normal color function in Korean adults. The test condition was performed on the differens distance and illumination. According to convergence condition of color vision target. On the appearance of EEG wave of visual stimulation on visual cortex. The most EEG wave style was delta wave, and the next amount wave form was beta wave and theta wave, and the least EEG wave form was alpha wave. The histogram of amplitude of EEG wave form was almost non-Gaussian shape, and the phase diagram of amplitude was almost all linear shape. On the kinds of color vision target, the frequency of EEG wave style appeared a similar results.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.30-31
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• 2002

하나의 구동기를 작동하여 거울을 변형시킬 때, 변형된 거울면의 형태를 영향 함수(influence function)라고 정의하며, 이러한 영향 함수를 이용하여 적응 광학계의 주요한 광학 요소인 변형 거울을 효과적으로 모형화하고 설계할 수 있다. 본 논문에서는 유한요소해석을 이용하여 계산된 변형 거울의 실제 영향 함수를 가우시안 함수(Gaussian function) 형태로 단순화하고, 추가로 구동기들 사이의 영향을 고려한 커플링 계수(coupling coefficient)를 도입하여, 주어진 구동기 배열에 대한 영향 함수를 결정하였다. (중략)