• Journal of The Korean Astronomical Society
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• v.19 no.1
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• pp.11-14
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• 1986

It is shown in this paper that the astigmatic property of single gravitational lens in static bounded gravitational field can be retained, if n-gravitating body as a whole acts simultaneously as gravitational lens.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.257-258
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• 2006

This paper presents the displacement sensor based on astigmatic method that has a small measurement range. The sensor has the characteristic that the measuring range is changed easily by exchanging a objective lens or distance between a objective lens and a collimator lens. The measuring range and resolution is evaluated by a laser interferometer.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.189-198
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• 2014

Purpose: The present has analyzed the correlation between the direction of lens and the amount of rotation upon soft toric contact lens fitting after classifying the corneal astigmatism. Methods: Soft toric contact lens was fitted on 114 with-the-rule astigmatic eyes with total astigmatism of at least -0.75 D in their 20s and 30s according to the fitting guideline of the manufacturer and the correlation between the astigmatic degree and the rotational direction/amount of rotation was analyzed by when keeping the eyes on the front and by changing the direction of gaze. As for re-orientation movement. The speed of lens re-orientation and total amount of lens rotation was compared and analyzed by corneal astigmatism after mis-location of lens of $45^{\circ}$ to temporal and nasal direction, respectively. Results: The positive correlations were shown between corneal astigmatism and the direction of lens rotation and between corneal astigmatism and the amount of lens rotation. Meanwhile, the amount of lens rotation was different by the direction of gaze however, there was no correlation with corneal astigmatism. The speed of lens re-orientation was fastest in the group of high astigmatic degree when the lens was mis-located to both temporal and nasal directions. Conclusions: For optimal axis stabilization of toric soft lens, it is proposed that the adjustment of fitting guideline considering corneal astigmatism is necessary since the current fitting guideline is only based on total astigmatism.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.1
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• pp.37-45
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• 2012

Purpose: The change of alignment between RGP lens and cornea according to the lens design was investigated by comparing the areas of fluorescein pattern in central and peripheral regions analyzed by astigmatic degree and corneal type when spherical and aspherical RGP lenses fitted in alignment. Methods: The fluorescein patterns of 90 eyes (19-30 years, $25.12{\pm}3.52$) having with-the-rule astigmatism were analyzed after spherical and aspherical RGP lenses fitted in alignment. Then, their fluorescent areas in central and peripheral regions were calculated and compared for the quantitative evaluation. Results: The case showing concordant base curve between spherical and aspherical RGP lenses in alignment fitting was 72% however, the possibility to have same base curves between spherical and aspherical RGP lenses in alignment fitting was to be less in the case of symmetric bowtietyped cornea and high astigmatism. The fluorescent area in peripheral region of aspherical RGP lens in alignment fitting was smaller than it of spherical RGP lens. Peripheral fluorescent areas in both RGP lenses decreased according to the increase of astigmatic degree and peripheral area in symmetric bowtie-typed corea was smaller than round-typed cornea's peripheral area. In the case of same astigmatic degree, peripheral fluorescent area of aspherical RGP lens was smaller in both corneal types. Conclusions: The results above suggest the changing degree in the alignment between RGP lens and cornea can be varied according to lens design, corneal astigmatism and corneal type. Thus, the results obtained from the quantitative analysis of the alignment between lens design and cornea may be used as the basic information about the establishment of guidelines for RGP lens fitting, the development of proper lens design, and different tear volume in partial regions.

• Journal of the Optical Society of Korea
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• v.17 no.2
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• pp.219-223
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• 2013

The purpose of this study was to determine the relationship between the spherical equivalent visual acuity (VA) and uncorrected astigmatism. On 108 emmetropic eyes, the spherical equivalent VA was measured for cross cylindrical lens (CC lens)-induced astigmatic eyes and the VA-astigmatism relation determined. On 158 astigmatic eyes, the spherical equivalent VA and corrected astigmatism were measured and the measured values were compared with the calculated values from the VA-astigmatism relation by correlation coefficient analysis. Subsequent to that, the relationship between spherical equivalent VA and uncorrected astigmatism was made. The relationship was fitted for an exponential equation. Correlation coefficient between calculated values by equation and measured values for astigmatic eyes was 0.991 (p<0.01). The relationship between the spherical equivalent VA and the uncorrected astigmatism was decided as follows (spherical equivalent VA / uncorrected astigmatism): 1.0 / 0.25 D, 0.9 / 0.50 D, 0.8 / 0.75 D, 0.7 / 1.00 D, 0.6 / 1.25 D, 0.5 / 1.50 D, 0.4 / 2.00 D, 0.3 / 2.50 D, 0.2 / 3.00 D, 0.1 / 4.00 D, and 0.05 / 4.75 D. In conclusion, the relationship table devised from this study is a useful reference for predicting uncorrected astigmatism by measurement of decimal VA in spherical equivalent.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.163.2-163
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• 2001

Confocal scanning microscopy (CSM) has been reported as an excellent method using the optical probe in scanning probe microscopy (SPM). Transmission or reflection confocal scanning microscopy (TCSM, RCSM) has been used in the three-dimensional reconstruction of specimen or the non-destructive measurement in vivo. The axial movement of the primary focal point having the information of specimen gives a good measurement performance with the great sensitivity. Application of the confocal theory and astigmatism to displacement measurement sensor uses the aperture as the pinhole or slit after collecting lens relating to confocal response in non-contact measurement; and astigmatic lens using four-segments detector as short-range sensor, long-range one combining the grating and rotary one hating the rotary directional grating. The aperture type can play an ...

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.263-267
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• 1998

Today's diopter of optical lens can reveal the derivation apparently compared with that of refraction measure lens. First, this is applicable when there is a difference in the shape and thickness basically and when the lens is used for a short distance. When measure and use it, an astigmatic difference is occurred by the discordant light passage. This is also applicable to optical lens with prism diopter lens and in some cases, must be corrected relating to the diopter incidently.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.3
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• pp.255-264
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• 2012

Purpose: In this study, the effect of lens fitting status on the contact area between spherical/aspherical RGP lens and the cornea having different astigmatic degree and corneal type was investigated for guiding the proper selection of RGP lens. Methods: Spherical and aspherical RGP lenses were applied on ninety eyes $(25.12{\pm}3.52years)$ having with-the-rule astigmatism by different fitting status. Then, their central, mid-peripheral and peripheral areas of fluorescein pattern were calculated and compared for the quantitative evaluation of the contact area between spherical/aspherical RGP lens. Results: The central and peripheral areas with the alignment fitting was significant different based on lens design. However, the central area didn't show any significant difference by lens design and corneal type when fitted in steep or flat. When analyzed by the corneal shape, both lenses with alignment and flat fitting had significant difference in central and peripheral areas. However, the central, mid-peripheral and peripheral areas with steep fitting didn't show the difference by corneal types. When analyzed by the astigmatic degree, the central and peripheral areas with alignment fitting changed proportionally to the increase of corneal astigmatism regardless of corneal shape. With steep and flat fitting, however, the central, mid-peripheral and/or peripheral areas in round- and symmetric bowtie-typed corneas showed the conflicting result when compared to those of alignment fitting when analyzed by the astigmatic degree. Conclusions: In this study, it was confirmed that the contact areas of cornea and RGP lens fitted steep and flat status were largely affected by the corneal type and corneal astigmatism rather than RGP lens fitted in alignment status. Also, this result commonly occurred in both spherical and aspherical RGP lenses.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.278-279
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• 2009

• 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.