• Korean Journal of Optics and Photonics
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• v.5 no.3
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• pp.372-378
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• 1994

A simple 2-step astigmatic rainbow holography method using the characteristics of holographic aberration is proposed. Point sources are used to record and reconstruct primary hologram. When the primary hologram is reconstructed, object image is divided into two components by the holographic astigmatism. This characteristics of holographic astigmatism and cylindrical lens power are used to obtain rainbow hologram of sharp image, no matter how far from the hologram the obseved image locates, in front of the hologram. And this hologram has optimum viewing distance long enough.enough.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.2
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• pp.77-83
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• 2006

We have studied the astigmatism according to the bevel position and the tilting(pantoscopic) angle of decentered spectacle lens for prism prescription. For prism prescription, generally we make a general spectacle lens into decentered spectacle lens. At this time the bevel position of decentered lens is a important matter, because the difference between optic axis and visual axis occur aberrations. Using the calculation we find that the case that the axis of bevel rotation band passes the front curvature center of (+) lens has a smaller astigmatism than the case that the axis of bevel rotation band passes the rear curvature center of (+) lens and that the case that the axis of bevel rotation band passes the rear curvature center of (-) lens has a smaller astigmatism than the case that the axis of bevel rotation band passes the front curvature center of (-) lens. We find the lens with higher refraction index has a smaller astigmatism.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.191-198
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• 1998

A method is described to produce off-axis hologram lenses without astigmatism for semiconductor lasers. We fabricated a holographic collimating lens by using dichromated gelatin film with high diffraction efficiency and without astigmatism which makes a collimated off-axis beam of semiconductor laser. We have designed the holographic collimating lens by applying the classical ray-tracing method to holographic diffraction. The elimination of astigmatism is obtained by choosing appropriate angles of recording and reconstruction beams. The hologram is recorded by use of Ar^{+}$ laser (488nm wavelength) and reconstructed by semiconductor laser(670nm wavelength). The physical parameters of recording and reconstruction angles, wavelength, and astigmatism are analytically calculated and experimentally confirmed.

• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.212-213
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• 2001

본 논문에서는 마이크로디스플레이용 광학계의 렌즈 설계와 시뮬레이션으로 구면수차, 비점수차, 왜곡, 색수차를 보정하여 설계한 광학계의 성능 평가를 소개하고자 한다.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.1
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• pp.117-124
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• 2004

In this paper, we took the clinical data of Korean eyes and designed the schematic eye with the same optical properties of the real eye. In the design process, we took the clinical emmetorpia data of young Korean adults collected in the past and analyzed to get a basic specification of the real eye for the design of schematic eye. The purpose of design was for the schematic eye to have the same optical properties of real eye in spherical aberration and astigmatism.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.55-60
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• 2002

In this paper, we investigate the MTF in image plane using the shifted magnitude, the shifted direction, and the astigmatism as the real amplitude distribution of incident beam in an optical system is shifted. The shifted magnitudes of incident beam are 0.0, 0.25, 0.5 and 0.75 and the shifted directions of incident beam are 0 and ${\pi}/2$. We also consider the optical system having the astigmatism which are $0.0{\lambda}$, $0.25{\lambda}$, $0.5{\lambda}$, and $0.75{\lambda}$. As the shifted magnitude of the real amplitude distribution of incident beam increases, the MTFs of sagittal and tangential direction in an optical system having an aberration free decrease, but that in an optical system having the astigmatism which is $0.75{\lambda}$ and the shifted direction of incident beam which is ${\pi}/2$ increases. We know from these results that the shift of the real amplitude distribution of the incident beam in an optical system compensates the effect of astigmatism as the shifted direction of that in an optical system is ${\pi}/2$, and Stiles-Crawford effect having the shifted real amplitude distribution of incident beam in pupil area is minimized the effect of astigmatism for eye.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.4
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• pp.355-360
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• 2010

Purpose: Analysis performance for spectacle lens which sales in domestic market and optimization design a spectacle lens which is corrected aberration. Methods: Measured center thickness, radius and aspherical surface coefficient for spherical and aspherical lenses which were ${\pm}$5.00D. Refractive index for every lens was 1.6 and they came from 4 different companies. I used 3 types of equipment to measure lenses. ID-F150 (Mitutoyo) : Center Thickness, FOCOVISION (SR-2, Automation Robotics) : Radius, PGI 1240S (Taylor Hobson) : Aspherical surface coefficient. Designed a lens which had 27 mm of distance from lens rear surface to center of eye, 4 mm of pupil diameter and small aberration on center vision $30^{\circ}C$. To shorten axial distance compared with the measured lens rise merits for cosmetic. Lens Design tool was CODE V (Optical Research Associates). Results: -5.00D aspherical lens had somewhat high astigmatism and distortion compared with the spherical lens. But it had a merit for cosmetic because of short axial height and decrease edge thickness. Improved a performance of distortion and ascertain merits for cosmetic due to short axial height and decrease edge thickness same as (-) lens in case of +5.00 aspherical lens. Though an optimization process front surface aspherical lens had a good performance for astigmatism and distortion and the merit for beauty compared with measured spherical lens. Conclusions: Design trend for domestic aspherical lens is decrease axial height and thickness to increase a merit for cosmetic not but increase performance of aberration. From design theory for optimization design front surface aspherical spectacle lens which has improved performance of aberration and merit for cosmetic at the same time compared with the measured lens. Expect an improved performance from design back aspherical lens compared with front aspherical lens.

• Korean Journal of Optics and Photonics
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• v.4 no.1
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• pp.28-35
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• 1993

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 $\sigma$ of aberration on the exit pupil in the interval of Fried parameter ${\Upsilon}_0$ 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.

• Korean Journal of Optics and Photonics
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• v.2 no.3
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• pp.127-132
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• 1991

We have obtained the analytic solutions of the four spherical mirror system free from the Seidel third order aberratios which are spherical aberration, coma, astigmatism, and distortion, Vignetting. Petzval field curvature, and optical properties according to the design parameters are numerically investigated and optimized. The numerical aperture of this system is 0.2 and the half field angle is $1.5^{\circ}$.

• Korean Journal of Optics and Photonics
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• v.17 no.3
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• pp.256-261
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• 2006

Wavefront aberrations of a laser beam that was reflected from an off-axis parabolic (OAP) mirror were measured to evaluate the optical performance of the OAP mirror. For a diamond turned OAP mirror, the root-mean-square (rms) value of higher-order aberrations was only $0.03{\mu}m$ for the laser beam size of about 34 mm. The other OAP mirror which was polished at a domestic company had the rms value of higher-order aberrations of $2.07{\mu}m$ for the same beam size. Although the diamond turned OAP mirror was well fabricated to have a small amount of aberrations, the aberrations were induced by the misalignment of the OAP mirror. Especially, 0 degree astigmatism increased with the sensitivity of $0.372{\mu}m/mrad$ when the OAP mirror was tilted in the tangential plane, which agreed well with the calculated results using a commercial ray tracing software.