• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.403-406
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• 1996

In this paper, the geometry between horizontal and vertical movement of lens is studied for automatic vergence control of horizontal moving axis stereo camera. When the disparity of stereo remains contant, the horizontal movement of camera lens for image disparity and the vertical movement for image focus have linear geometry. Using this linearity, we can control the vergence of stereo camera only by focusing of stereo camera lens.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.1
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• pp.21-30
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• 2011

Purpose: The study was performed to compare the differences in lens rotation, lens movement by blinking and lens centration with alignment or steep fitting of soft contact lens in normal and dry eyes. Methods: Total 40 eyes (aged 20~30 years) were classified into the normal (n=20) or dry eye group (n=20) by the diagnosis methods for dry eyes and worn soft contact lens (polymacon material) with alignment fitting or steep fitting. Lens rotation, lens movement by blinking and lens centration were separately measured immediately after lens wearing and after stabilization of tear film and compared by fitting states of soft contact lenses. Results: With steep fitting of soft contact lens in dry eyes, averaged lens rotation immediately after lens wearing was not significantly different from that of the normal eye group with alignment fitting however, lens rotation after stabilization in dry eyes was significantly larger than that in normal eyes. Any significant difference in lens movement by blinking was not shown in normal eyes. However, lens movement by blinking in dry eyes was increased with steep fitting. The range of lens centration on cornea in normal eyes with alignment fitting was more vertically distributed. On the other hand, the range of lens centration on cornea in dry eyes with alignment fitting was more horizontally distributed. Lens centration was shown to be changed by stabilization of tear film. That is, lens centrations were somewhat vertically widespread immediately after lens wearing and restrictively distributed in horizontal direction, respectively, with steep fitting in dry eyes. Conclusions: These results suggested that lens movements and centration in dry eyes were different from those of normal eyes. Especially, those differences between normal and dry eyes were much bigger with steep fitting of soft contact lenses. Thus, those differences should be considered for the comfortable and safe fitting of soft contact lens in dry eyes.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.2
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• pp.40-49
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• 1992

In this paper,a new approach-using the linear movement of the lens location in a camera and focal distance in each location for the measurement of the depth of the 3-D object from several 2-D images-is proposed. The sharply focused edges are extracted from the images obtained by moving the lens of the camera, that is, the distance between the lens and the image plane, in the range allowed by the camera lens system. Then the depthin formation of the edges are obtained by the lens location. In our method, the accurate and complicated control system of the camera and a special algorithm for tracing the accurate focus point are not necessary, and the method has some advantage that the depth of all objects in a scene are measured by only the linear movement of the lens location of the camera. The accuracy of the extracted depth information is approximately 5% of object distances between 1 and 2m. We can see the possibility of application of the method in the depth measurement of the 3-D objects.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.5-13
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• 2008

Purpose: This review article was written to investigate what kind of forces are acting on the contact lens fitted on the cornea and its subsequent motion. Methods: A capillary action-induced force develops in the tear layer between the lens and cornea, which leads to the restoring force due to difference in layer thickness according to lens rotation. The characteristics of the lens movement can be determined by the various factors such as friction between eyelid and lens, acceleration force based on blinking and the restoring force incorporated with the viscous damping force. A mathematical model which consists of the differential equations and their numerical solution was proposed to analyze the damped motion of lenses. The model predicts the time dependence of lenses during and after the blink varying the BC, blink period and eyelid pressure. Results: It was found that both the blink period and lid pressure increases the movement increases because of the enhanced lid friction. As the BC increases the viscous damping reduces due to the lacrimal layer's increase which resulted in the enhanced lens motion. After blink the lens illustrates the damped oscillation because of the restoring force by the increased lacrimal layer thickness and reduced viscous resistance. The time for the lens to return to the equilibrium shortens as the BC increase because of the resistance reduction. Conclusions: The movement of the contact lens is governed by the characteristics of the lacrimal layer between the lens and cornea as well as the lid blink.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.1
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• pp.1-7
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• 2007

To investigate the momentary movement pattern of soft contact lens(SCL) depending on wearing time, eight types of soft contact lenses were worn by 10 normal subjects and the momentary movements of SCLs were estimated using by high speed camera(FASTCAM ultima 1024). When the momentary movements of SCLs in the cornea between blinkings were compared after 15 min wearing, the vertical movements of all eight SCLs were about 2 times larger than the horizontal movement but the extent of these movement difference was a function of kinds of SCLs. The momentary moving distance of SCL varied from the kinds of SCLs, which A and B lens, daily wear lens, moved significantly larger distance compared with other SCLs. The momentary movements between blinkings decreased significantly after 8hr wear of SCLs. The extents were different when SCLs were compared with each other, which the reduction range of horizontal and vertical movement was 24.6~60.0% and 20.4~94.3%, respectively. The A, B and C lenses which had relatively higher water content showed the larger movement reduction after SCL wear. This results suggest that wearing SCL for some hours decreases the movement of SCl, which can induce the change of tear flow.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.1
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• pp.27-35
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• 2012

Purpose: The present study was conducted to compare any difference caused by pigmentation in the centrations and movement patterns on the cornea between circle and soft contact lens with identical material and parameters during lens wearing. Methods: Soft and circle contact lenses with identical material and parameters were applied to twenty eyes with normal tear volume for 3 hrs a day during a total of 5 days and then their lens centrations, the moving distances and rotations by repeat blinking were compared. Results: The lens centration beyond the fitting criteria was shown in initial wears of both soft contact lens and circle contact lens. However, the centration of soft contact lens was changed to the pupil center for being suitable to the fitting criteria with longer wearing time. On the other hand, the decentration of circle contact lens in the horizontal direction was still presented even with longer wearing time. The moving distances of soft contact lens and circle contact lens decreased with the expand of lens wearing but were not significantly different between total wearing period and daily wearing time. The rotation of circle contact lens by repeat blinking was significantly different from that of soft contact lens even when the wearing period was extended. Conclusions: We revealed that the lens centration and movement of circle contact lens on cornea were different from those of regular soft contact lens resulting in bigger difference with the expand of wearing period in the study.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.2
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• pp.123-133
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• 2011

Purpose: The present study was conducted to analyze any difference in the movement of aspheric RGP lens by the amounts of keratometiric astigmatisms using keratometer and corneal topography. Methods: Corneal curvatures in thirty six eyes of males and females of with-the-rule keratometric astigmatisms in their twenties were measured by a keratometer and worn aspheric RGP lenses. Then, lens rotations, vertical and horizontal movements of lens by blinking were measured to compare with lens movements when aspheric RGP lenses were fitted by total keratometric astigmatisms using corneal topography. Results: The case having higher amount of central keratometric astigmatism was 61.1% of subjects, however, 36.1% of subjects showed higher total keratometric astigmatism indicating that central keratometric astigmatism was not always bigger than total keratometric astigmatism. Since over 0.25 diopter difference between total and central keratometric astigmatisms was shown in 19 eyes (52.8% of subjects), the prescription for lens fitting could be changed. Significant difference in horizontal movement was detected with increase of astigmatism when it compared based on the amount of keratometric astigmatism measured by a keratometer. However, there was no significant difference in lens rotation, horizontal and vertical movements by comparison with the amount of total keratometric astigmatism using a corneal topography. When central keratometric astigmatism measured by keratometer was bigger than total keratometric astigmatism estimated by corneal topography, bigger lens rotation was shown compared with opposite case. Also, the tendency of bigger lens rotation was measured with the increase of keratomatric astigmatism in the case of same prescription having same base curves with same amount of keratometric astigmatism but different curvatures. Conclusions: From the present study, we concluded that lens movements on cornea were not totally different when aspheric RGP lens fitted on with-the-rule astigmatism by keratometer and corneal topography. However, there was some difference in certain lens movements. Therefore, we concluded that further study on the relationship between the prescriptions for lens fitting should be conducted for improving the rate of successful lens fitting by keratometer or for the proper application of corneal topography for lens fitting.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.1
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• pp.145-159
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• 2004

A mathematical model and its computer solution program were proposed to analyze the motion of contact lenses which are being subject to lid-blinking. The equation was derived by incorporating an acceleration induced lid's force exerting on the contact lens, the viscous damping resistance in the tear layer beneath the lens and the sliding frictional force between the lid and the contact lens surface into the formulation of differential equation describing the vibration. The model predicts the time-dependent displacement from the equilibrium postion during/after the blinking. During the blinking, as the time for the completion of one cycle of blinking decreases the off-the-equilibrium displacement of contact lens increases while the decrease of diameter in the contact cause the opposite effect. It is found that lid pressure exerting on the lens cause an insignificant lens displacement from the equilibrium position. After blinking the frequency of damped oscillation of contact lens decreases as the diameter of lens increases, due to the incresed surface while the reduced blinking time does not cause a significant frequency change. This is because that driving force for the contact lens movement posterior to blinking is the capillary-induced force not the lid force.

• Applied Microscopy
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• v.29 no.2
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• pp.231-239
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• 1999

Morphological changes of Drosophila ocellar corneagenous cells were studied to the development with electron microscopy, and the movement of produced proteins was traced with autoradiography. Corneagenous cells of immediate postemergence showed very active secretion pattern. However, a few days after the emergence, the secretory activity of corneagenous cell was supposed to be dropped suddenly. In autoradiography, almost of proteins that produced by corneagenous cells moved toward lens. From this, it was supposed that the corneagenous cells do not function in photoreceptor cells rather in the formation of lens at the postemergence stage. Corneagenous cells of pupal stage were well developed. In the period of lens formation, rER of corneagenous cells were well developed and it suggested very active material metabolism. Granules and microtubules were also frequently observed and the later would be a pathway of the movement of materials. In conclusion, corneagenous cells were well developed at vigorous lens forming stage. After emergence, when the lens formation was completed, both the function and the size of corneagenous cells were reduced.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.2
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• pp.33-39
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• 2003

A new microlens fabrication technique, the excimer laser lithography is developed. This bases on the pulsed laser irradiation and the transfer of a chromium-on-quartz reticle on to the polymer surface with a proper projection optics system. An excimer laser lithography system with 1/4 and 1/20 demagnification ratios was constructed first, and the photoablation characteristics of the PMMA and Polyimide were experimentally examined using this system. For two different shapes of microlenses, a spherical lens and a cylindrical lens, fabrication techniques were investigated. One for the spherical lens is a combination of the mask pattern projection and fraction effect. The other for the cylindrical lens is a combination of the mask pattern projection and the relative movement of a specimen. The result shows that various shapes of micro optical components can be easily fabricated by the excimer laser lithography.