• Current Optics and Photonics
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• 제7권6호
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• pp.692-700
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• 2023

We present a method for improving the accuracy of the modal wavefront reconstruction in the radial shearing interferometers (RSIs). Our approach involves expanding the reduced radial terms of Zernike polynomials to high-order, which enables more precise reconstruction of the wavefront aberrations with high-spatial frequency. We expanded the reduced polynomials up to infinite order with symbolic variables of the radius, shearing amount, and transformation matrix elements. For the simulation of the modal wavefront reconstruction, we generated a target wavefront subsequently, magnified and measured wavefronts were generated. To validate the effectiveness of the high-order Zernike polynomials, we applied both low- and high-order polynomials to the wavefront reconstruction process. Consequently, the peak-to-valley (PV) and RMS errors notably decreased with values of 0.011λ and 0.001λ, respectively, as the order of the radial Zernike polynomial increased.

• 한국광학회지
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• 제17권3호
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• pp.256-261
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• 2006

본 논문에서는 비축 포물 거울을 통과한 레이저 빔의 파면을 측정하는 방식으로 국내 및 국외에서 제작된 비축 포물 거울을 평가하였으며, 이로부터 비축 포물 거울의 집속 성능 및 정렬 민감도를 측정하였다. 국외에서 제작된 비축 포물 거울은 직경 약 34 mm의 레이저 빔에 대해 고차 파면 수차(higher-order aberration)의 rms 값이 $0.03{\mu}m$ 정도로 작아 광학적으로 좋은 품질을 갖는 것으로 판명되었다. 국내에서 제작된 비축 포물 거울은 같은 34 mm의 레이저 빔에 대해 고차 파면 수차의 rms 값이 $2.01{\mu}m$나 관측되어 아직 개선이 필요한 것으로 보인다. 또한, 비축 포물 거울의 회전 정렬 오차에 대한 비점수차(astigmatism)의 민감도를 측정한 결과 회전 정렬 오차에 대한 비점수차의 민감도는 $0.371{\mu}m/mrad$인 것으로 관측되었다. 이는 광선 추적 소프트웨어를 사용하여 계산한 값과 거의 같은 양으로 이러한 비점수차의 정렬 민감도 측정은 비축 포물 거울을 정렬하는데 도움을 줄 것으로 생각된다.

• Current Optics and Photonics
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• 제8권2호
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• pp.151-155
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• 2024

Optical systems often suffer from optical aberrations caused by imperfect hardware, which places significant constraints on their utility and performance. To reduce these undesirable effects, a comprehensive understanding of the aberrations inherent to optical systems is needed. This article presents an effective method for aberration detection using Zernike polynomials. The process involves scanning the object plane to identify the optimal focus and subsequently fitting the acquired focus data to Zernike polynomials. This fitting procedure facilitates the analysis of various aberrations in the optical system.

• 한국안광학회지
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• 제14권2호
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• pp.35-39
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• 2009

목적: 본 연구는 각막지형검사기의 각막형상을 이용하여 각막수차를 구현하는 프로그램을 개발하고자 하며, 개발된 프로그램을 이용하여 저니케 다항식(Zernike Polynomial)으로 파면과 각막수차를 구현하고자 한다. 방법: 각막지형검사기인 ORBSCAN의 각막형상 데이터로부터 각막의 형상을 재구성하기 위해 저니케 다항식을 사용하였으며, 이때 동공의 유효구경은 6 mm를 고려하였다. 구현된 각막형상으로부터 광선추적을 사용하여 동일한 광학적 거리의 파면을 구현하는 프로그램을 개발하였으며, 파면으로부터 6차 28항의 저니케 계수로 각막수차를 구현하였다. 결론: 본 연구에서는 각막지형검사기의 각막형상으로부터 각막의 수차와 파면을 구현하는 프로그램을 개발하였으며, 이러한 결과는 각막지형검사기 개발과 콘택트렌즈 및 OK렌즈 처방에 유용하게 적용될 수 있으리라 사료된다.

• International Journal of Internet, Broadcasting and Communication
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• 제16권3호
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• pp.77-84
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• 2024

Aberration is still a problem for making augmented reality displays. The existing methods to solve this problem are either slow and inefficient, consume too much battery, or are too complex for straightforward implementation. There are still some problems with image quality, and users may suffer from eye strain and headaches because the images provided to each eye lack accuracy, causing the brain to receive mismatched cues between the vergence and accommodation of the eyes. In this paper, we implemented a computer simulation of an optical aberration using Zernike polynomials which are defocus, trefoil, coma, and spherical. The research showed that these optical aberrations impact the Point Spread Function (PSF) and Modulation Transfer Function (MTF). We employed the phase conjugate technique to mitigate aberrations. The findings revealed that the most significant impact on the PSF and MTF comes from the influence of spherical aberration and coma aberration.

• 한국컴퓨터정보학회논문지
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• 제23권2호
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• pp.1-7
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• 2018

The adaptive optics for compensating for optical wavefront distortion due to atmospheric turbulence has recently been used in systems that improve beam quality by eliminating the aberrations of high power laser beam wavefront. However, unseen-mode, which can not be measured in the wavefront sensor, increases the instability of the laser beam wavefront compensator on the adaptive optics system. As a method for improving such instability, a mathematical method for limiting the number of singular values is used when generating the command matrix involved in generation of the drive command of the wavefront compensator. In the past, however, we have relied solely on experimental methods to determine the limiting range of the singular values. In this paper, we propose a criterion for determining the limiting range of the singular values using the driving characteristics and the correlation technique of the wavefront compensator's actuators and have proved its performance experimentally.

• 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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• 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.

• Current Optics and Photonics
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• 제6권5호
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• pp.473-478
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• 2022

To overcome the capture-range problem in phase-diversity phase retrieval (PDPR), a geometrical-optics initial-estimate method is proposed to avoid a local minimum and to improve the accuracy of laser-wavefront measurement. We calculate the low-order aberrations through the geometrical-optics model, which is based on the two spot images in the propagation path of the laser, and provide it as a starting guess for the PDPR algorithm. Simulations show that this improves the accuracy of wavefront recovery by 62.17% compared to other initial values, and the iteration time with our method is reduced by 28.96%. That is, this approach can solve the capture-range problem.

• Current Optics and Photonics
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• 제6권1호
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• pp.1-9
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• 2022

This paper proposes a robust, simple zonal wavefront-estimation method in a grid sampling model. More slopes are added to the integral equation of the algorithm to improve the accuracy and convergence rate of this approach, especially for higher-order optical aberrations. The Taylor theorem is applied to clarify the mathematical description of the remaining error in the proposed method. Several numerical simulations are conducted to ensure the performance and improvement in comparison to the Southwell and previous algorithm. An experiment is also conducted according to deflectometry output and the results are verified using a reference measured with a stylus system.