• Current Optics and Photonics
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• v.7 no.1
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• pp.1-14
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• 2023

Wavefront-coding imaging can achieve high-quality imaging along with a wide range of defocus. In this paper, the anti-laser detection and damage performance of wavefront-coding imaging systems using different asymmetric phase masks are studied, through modeling and simulation. Based on FresnelKirchhoff diffraction theory, the laser-propagation model of the wavefront-coding imaging system is established. The model uses defocus distance rather than wave aberration to characterize the degree of defocus of an imaging system. Then, based on a given defocus range, an optimization method based on Fisher information is used to determine the optimal phase-mask parameters. Finally, the anti-laser detection and damage performance of asymmetric phase masks at different defocus distances and propagation distances are simulated and analyzed. When studying the influence of defocus distance, compared to conventional imaging, the maximum single-pixel receiving power and echo-detection receiving power of asymmetric phase masks are reduced by about one and two orders of magnitude respectively. When exploring the influence of propagation distance, the maximum single-pixel receiving power of asymmetric phase masks decreases by about one order of magnitude and remains stable, and the echodetection receiving power gradually decreases with increasing propagation distance, until it approaches zero.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.129-130
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• 2009

In order to determine the aberration coefficients of an aspheric lens with a small diameter, its transmitted wavefront was compensated with a null CGH and an auxiliary convex lens. The configuration of the measuring system and the fabrication step of CGHs could be simplified by using a reflective amplitude-type CGH as null optics. The compensated waterfronts of several sample lenses were measured and analyzed, and consequently the performance of the CGH was evaluated.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.3
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• pp.61-64
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• 2008

Purpose: The analysis of individual eye model designed from clinical demonstration about emmetropia shows that the aberration would be changed by the wave change. Method: The model on the basis of clinical demonstration of eye ball is designed in a form of having 4 refraction surfaces and a constant refractive index. We analyzed designed twelve individual eye model into aberrations changes, as giving changes Fraunhofer lines's six wavelengths. Result: About individual eye model, change in the wavelength of the wavefront aberrations analysis using the Zernike coefficient. This data indicate that the shorter wave is, the more defocus increases and the deviation value of spherical aberration and RMS are widened. Conclusion: As quantity of defocus according to result wavelength change is shorter and shorter, inclination which is similar twelve individual eye model is bigger and bigger and individual eye model majority of cases, little change, and change is shown in part individual eye model is a significant performance degradation can be raised.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.78-79
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• 2002

눈의 시력을 진단하는 도구 또는 장비로는 자각식 측정법인 시력표, 타각식 계측기로는 검영기와 자동굴절력측정기 등이 있다. 이들 방법으로 얻는 결과는 시력 또는 굴절력 값으로 제한된다. 그러나 인체안도 일반 광학계와 같이 공간적으로 불균일한 광학적 특성을 가지기 때문에, 눈의 광학적 기능을 정확하게 진단하기 위해서는 공간에 따른 광학수차 분포를 측정할 필요가 있다. 특히 엑시머레이저를 이용한 굴절각막교정수술에서, 광학수차 정보는 정교한 교정수술을 위한 기초 자료가 될 수 있다. (중략)

• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.299-304
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• 1996

We numerically determined the direction of ray and the average ray-crossing position from the shape of the wavefront on the exit pupil of optical system which had aberrations and apodized aperture. This position was calculated easier and closer to the position of the maximum intensity than that calculated by Safa's method when the aberration is greater than about 2λ.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.161-166
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• 1997

A improved method to measure the wavefront aberration of aspheric lens is described. In this study, which is a kind of lateral shearing interferometry, a sinusoidal diffraction grating is used for better quality of interferogram. Also,the grating is inclined to horizontal axis for obtaining the two orthogonal derivatives and minimizing moving error simultaneously. Measurement result shows that the repeatability is about 6 times better then that of previouse Ronchi Test.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.122-122
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• 2004

최근 휴대폰, 디지털 카메라, 캠코더, MP3 플레이어, 노트북 PC 등 휴대용 디지털 기기의 보급이 확산되면서 휴대용 저장장치의 수요가 급증하고 있다. 휴대용 저장장치의 요구사항으로 초소형화, 대용량화를 들 수 있는데, 이를 만족할 수 있는 기술로 사용될 수 있는 것이 Blu-Ray를 이용한 광 저장장치이다. 초소형 광저장장치에 사용되는 3cm 디스크에는 1.5Gbyte를 기록할 수 있으므로 기존의 휴대용 저장장치에 비해 가격이 저렴하며 대량배포가 가능하다.(중략)

• Journal of the Optical Society of Korea
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• v.1 no.1
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• pp.41-43
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• 1997

We report the operation of a self-adaptive vector phase conjugate laser (VPCL) oscillator which compensates intracavity polarization distortion and wavefront aberration simultaneously. The VPCL in Nd:YAG gain media produce an output with energy of 125mJ in a 20ns single-longitudinal-mode pulse at 10Hz, which is unaffected by intracavity polarization distortion.

• Korean Journal of Optics and Photonics
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• v.26 no.4
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• pp.217-225
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• 2015

This paper shows the best selection and combination of glass in lens design, to correct a chromatic aberration using achromatic and apochromatic conditions. Using this research result, we have designed a telecentric lens for machine vision in the full range of visible light. We obtain good optical quality in the form of a quite small RMS wavefront error of $0.057{\lambda}$ in the super-broadband wavelength range 380 nm -780 nm. This result is better than that for a common telecentric lens in the visible wavelength range 486.1-656.2 nm.

• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.50-55
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• 2005

A method for measuring the wavefront error and the modulation transfer function(MTF) of large aperture optics using an unequal path interferometer is presented. A bidirectional shearing interferometer is used for collimation testing of the measurement system. A large aperture Fizeau interferometer with long optical path difference measures the wavefront error of the optics under test by using a $\Phi$ 400 mm off-axis parabolic mirror. The MTF is also measured at the wavelength of the interferometer by changing the laser light into partially incoherent light. Test results of a $\Phi$ 300 mm Cassegrain type satellite telescope made in Korea are presented.