• Journal of the Optical Society of Korea
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• 제12권3호
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• pp.186-191
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• 2008

A phase retrieval method using an error reduction algorithm is developed for reconstructing a wavefront aberration of an 100-TW Ti:sapphire laser pulse from the measurement of a focal spot. The phase retrieval method can successfully reconstruct a wavefront aberration of a 100-TW Ti:sapphire laser pulse, and the reconstructed wavefront aberration shows a good agreement with the wavefront aberration measured with a wavefront sensor. The effect of the dynamic range and the intensity noise on the reconstruction is also investigated in reconstructing a wavefront aberration of an 100-TW Ti:sapphire laser pulse.

• 정보저장시스템학회논문집
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• 제3권3호
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• pp.135-138
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• 2007

Using a Shack-Hartmann sensor and sub-wavelength sized pinhole point source, we develope an optical testing system that measures the wavefront error of high numerical aperture and small sized optical components. The subwavelength sized pinhole generates perfect spherical waves with large diffraction angle and this makes possible to test high numerical aperture optics. The Shack-Hartmann sensor reconstructs the wavefront and calculates the aberrations. We make a home-made reference plane wave source which generates nearly perfect plane waves and the calibration with this plane source gives the overall uncertainty of the optical testing system 0.010 $\lambda$ rms.

• Journal of the Optical Society of Korea
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• 제19권1호
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• pp.45-54
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• 2015

In this study, a novel parallel wavefront correction system architecture is proposed, and a model-based tabu search (MBTS) algorithm is introduced for this new system to compensate wavefront aberration caused by atmospheric turbulence in a free-space optical (FSO) communication system. The algorithm flowchart is presented, and a simple hypothetical design for the parallel correction system with multiple adaptive optical (AO) subsystems is given. The simulated performance of MBTS for an AO-FSO system is analyzed. The results indicate that the proposed algorithm offers better performance in wavefront aberration compensation, coupling efficiency, and convergence speed than a stochastic parallel gradient descent (SPGD) algorithm.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.160-161
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• 2005

Using a Shack-Hartmann sensor, we construct an optical testing system measuring the wavefront error of small optical components. The systematic error of the sensor is compensated with a reference plane-wave system that produces almost perfect plane waves. Several types of lenses are tested using a point source that generates spherical waves emitted from a pinhole. The results of the optical testing obtained with the Shack- Hartman sensor are compared with those measured with Zygo interferometer.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.384-387
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• 1995

Two axes lateral-shearing interferometer(LSI) specially devised for production line inspection lenses is presented. The interferometer composed with four prisms and a dove prism can test the lens performance including asymmetric aspheric lens. The dove prism which rotates the input image with respect to optical axis makes it possible. The wavefront passing through the test lens is reconstsucted by the phase derivative obtained form the two axes LSI system. Zernike-polynomials fitting of this wavefront is presented for determinating quantitative aberration of aspherical lenses.

• 한국광학회:학술대회논문집
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• 한국광학회 2005년도 제16회 정기총회 및 동계학술발표회
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• pp.132-133
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• 2005

• 한국안광학회지
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• 제10권4호
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• pp.357-364
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• 2005

본 연구에서는 안광학계의 성능평가 장비 개발을 위한 눈과 같은 광학계의 파면수차를 구현하는 프로그램을 개발하였다. 광학계의 파면수차를 재구성하기 위한 프로그램은 matlab을 사용하였으며, 파면수차 합수는 modal 방법에 의한 저니케 다항식을 사용하였다. 본 연구에서 개발된 파면수차 재구성 프로그램을 검증하기 위해 cooke triplet 광학계의 저니케 계수(n=7)를 code V를 사용하여 계산하였으며, 이 결과를 본 연구에서 개발된 프로그램에 의해 계산된 결과와 비교하였다. 이 때 사용한 저니케 계수는 n=2, 3, 4, 5, 6, 7, 8, 9, 그리고 10인 경우이며, sub-aperture 수는 1,253개이다. 개발된 프로그램의 검증결과 n=4 이상인 경우에는 본래의 파면수차와 거의 일치하였으며, n=7인 경우의 저니케 계수는 code V에서 계산된 저니케 계수와 동일함을 알 수 있었다. 이러한 연구 결과는 적응광학을 사용한 안광학계의 성능평가 장비 개발을 위한 핵심 기술로 사용될 것이다.

• Journal of the Optical Society of Korea
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• 제16권3호
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• pp.228-235
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• 2012

It is very important to analyze effectively the tolerance of an optical system with high resolution as the projection lens of photolithography or as the objective lens of a microscope. We would like to find an effective assembly structure and compensators to correct aberrations through global wavefront sensitivity analysis using Zernike polynomial expansion from the field and pupil coordinates rather than from only pupil coordinates. In this paper, we introduce global wavefront coefficients by small perturbations of the optical system, and analyze the optical performance with these coefficients. From this analysis, it is possible to see how we can enlarge the tolerance through the proper assembly structure and compensators.

• Journal of the Optical Society of Korea
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• 제16권3호
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• pp.236-242
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• 2012

In general, such methods as interferometers or wavefront sensors are commonly used for testing of an optical system and optical components. In these cases, the surrounding environments are unlikely to affect the measurements. On the other hand, intraocular lenses of hydrophilic materials with special properties experience a certain difficulty in testing the optical properties. An intraocular lens is dried in the air, which causes deformation and changes the optical characteristics such as index of refraction and thickness. Thus, it is hard to measure the optical characteristics of an intraocular lens by using common methods. In this study, a special structure is used for measuring of the transmission wavefront aberration and effective focal length of an intraocular lens of hydrophilic materials by using a Shark-Hartmann sensor among the various measuring methods. As an application of this measuring method, this study shows a simple method to measure the index of refraction of unknown liquids with a plano-convex lens with a well known index of refraction. Also, this method is used to measure the optical properties of a plano-convex such as index of refraction and curvature by using a liquid with a well known index of refraction.

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
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• pp.126-127
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• 2003

눈의 시력을 진단하는 도구로는 시력표, 검영기, 빔프로젝터, 자동굴절력측정기 등이 있다. 파면분석기(wavefront aberrometer)를 이용하면 눈의 굴절력 및 난시도수 외에도 광학적 고위수차(higher order aberration)를 표현하는 파면수차함수를 산출할 수 있기 때문에, 눈의 결상 능력을 정확하고 정밀하게 진단할 수 있는 가능성을 가지고 있다. 따라서 파면분석기는 현재까지 사용되고 있던 시력 또는 굴절력 계측기들의 다음 세대를 이어갈 것으로 전망하고 있다. (중략)