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조두진(Doo Jin Cho) 한국광학회 1993 한국광학회지 Vol.4 No.1
수치가 정확히 알려지지 않은 결상계에 있어서, exit pupil에 인위적인 위상의 random fluctuation을 도입하고 복스펙트럼 스펙클 영상법(bispectral speckle imaging)을 이용하므로서 수차의 효과를 극소화하여 거의 회절한계의 영상을 얻을 수 있다. Defocus, 구면수차, 코마수차, 비점수차가 각각 1파장씩 있을 때, 주어진 사용영상수(50개)에 대해서 Gaussian random phase model의 correlation length가 어느 정도일 때 최적의 결과를 얻을 수 있는지를 점 물체에 대해 컴퓨터 시뮬레이션을 시행하므로서 연구하였다. 평가기준으로서는 복원된 점물체에 대한 point spread function의 FWHM, normalized peak intensity, MTF 그리고 visual inspection을 채용하였는데, exit pupil 위해서 Fried parameter ro범위에 대한 수차의 차의 rms값 σ가 구면수차에 대해서는 0.27~0.53 파장일 때, defocus와 비점수차에 대해서는 0.24~0.36 파장일 때 좋은 결과를 주는 것으로 나타났고, 코마수차의 경우에는 좋은 결과를 얻을 수 없었다. In the case of an imaging system affected by aberrations which are not precisely known, the effect of aberrations can be minimized and near-diffraction-limited images can be restored by introducing artificial random phase fluctuations in the exit pupil of the imaging system and using bispectral speckle imaging. In order to determine the optimum value of the correlation length for Gaussian random phase model, computer simulation is performed for 50 image frames of a point object in the presence of defocus, spherical aberration, coma, astigmatism of 1 wave, respectively. In terms of the criterion of performance, the FWHM of the point spread function, normalized peak intensity, MTF and visual inspection of the restored object are employed. The optimum value for the rms difference σ of aberration on the exit pupil in the interval of Fried parameter ro is given by 0.27~0.53 wave for spherical aberration, and 0.24~0.36 wave for defocus and astigmatism, respectively. It is found that the bispectral speckle imaging technique does not give good results in the case of coma.
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회절광학을 이용한 적외선 광학계 설계 및 BSP를 이용한 성능 평가, 분석
공현배,조두진,Kong, Hyun Bae,Cho, Doo Jin 한국광학회 2013 한국광학회지 Vol.24 No.4
본 논문에서는 두 매의 BD-2 렌즈와 비구면 회절 광학을 포함하는 F/1.2, 시야각 $15.2^{\circ}$와 $8-14{\mu}m$의 원적외선 파장대역을 가지는 광학계를 설계하였다. 이 광학계는 uncooled camera에 사용될 수 있으며, 광학계의 분석은 BSP로 진행되었다. 회절광학은 주어진 두께를 가지는 물리적인 면으로 취급하였으며, 분석결과를 출사동공법과 같은 기존 방법들에 의한 것과 회절차수 합성법에 의한 것과 비교하였다. An F/1.2 infrared optical system that involves two aspheric BD-2 lenses and an aspheric diffractive surface was designed over $8-14{\mu}m$ with a field angle of $15.2^{\circ}$. The system may be used in uncooled cameras and is analyzed using beam synthesis propagation (BSP). The diffractive surface is modeled as a physical surface with a given thickness, and results are compared with those obtained by conventional methods, such as the exit-pupil method and a method which superposes diffraction orders.
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조두진 조선대학교 기초과학연구소 1981 自然科學硏究 Vol.4 No.1
Spherically symmetric dust was studied using the Einstein field equation in the synchronous, comoving reference frame. It was assumed that this dust system was initially at rest, and had the following density distribution : p(r, 0)=p_α for 0≤r≤r_α, p(r, 0)=p_b for r_α≤r≤r_b, p(r, 0)=0 for r≥r_b, where p_α and p_b were constants. In the case of p_α>p_b, it was shown that the region 0≤r≤r_α collapsed to singularity in the same way as the uniform density distribution case, and that the density distribution in the region r_α≤r≤r_b became nonuniform as time lapsed. In the case of p_α<p_b, so called "shell-crossing singularity" occurred. It was also found that other choices of B(r, 0) than r^2 in the region r_α≤r≤r_b did not remove this singularity.
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Semiconductor-Liquid Junction의 전기화학적 특성
조관상,최승평,이관교,최성휴,서동주,조두진,이수일 조선대학교 기초과학연구소 1981 自然科學硏究 Vol.4 No.1
Ⅲ-Ⅳ semiconductor films, as prepared by the electroless deposition method, have been studied in the liquid-junction solar cell to determine the open-circuit voltage (V_oc) and the power concersion(η). The CdS and CdZnS films prepared by this method have many of the advantages of those made by the spray deposition method, such as the ease of coating large areas and simplicity of the process. For the CdS film cell, the V_oc and η were found to be 0.6 V and 0.127%, respectively. For the CdZnS film cell, the V_oc and η were found to be 0.56 V and 0.135%.
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