• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.279-288
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• 2000

The variations of output energy due to tilt output coupler for different types of pulsed Nd:YAG laser resonators were compared by measuring FWHM (full width at half maximum) which means the width of angle displacement where maximum output energy decreases to half value. We proposed a new configuration of pulsed solid-state laser resonator which had high FWHM for tilting of output coupler and which was little sensitive for tilting of rear optics. We proved that our laser resonator had high alignment stability using ABeD ray matrix method because the ray matrix of such a resonator corresponded to unit matrix. atrix.

• Korean Journal of Optics and Photonics
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• v.25 no.4
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• pp.207-215
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• 2014

In this paper the radial stiffness associated with stacking sequence effects, and the dimensional stability issue associated with thermally induced surface deformation in quasi-isotropic laminates due to the effect of stacking sequence and additional resin layer technique, are numerically investigated. Finally, the influence of surface resin layer techniques for fiber print-through mitigation in a composite mirror is tested for evaluation of surface accuracy across varying thermal conditions.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.319-321
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• 2004

We report on progress in developing high-power excimer lasers as well as UV-optics for creating low-temperature poly silicon (LTPS). A new high-power excimer laser offers 315 Watts with high pulse to pulse energy stability. Larger substrates can now be processed in better quality with either the SLS process or the new optics for line beam excimer laser annealing.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.161-164
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• 2001

The purpose of our study was stability of tear film for Korean. In the 1970s, the major problem for the contact lens practitioner was the management of contact lens parameters. In the 1980s, oxygen permeability was the main problem in contact lens practice: now it is dry eyes. To appropriately fit the patient with contact lenses it is imperative to know in advance if the patient has a marginal dry eye. Based on the initial diagnosis appropriate care can be taken to minimize problems with the result that the patient can successfully wear contact lenses. A well known test for dry eyes is Schirmer test which has shown to be useful for diagnosing Sjogren syndrome. Biomicroscopy can often unmask numerous problems. The classical test for marginal dry eye is measuring the tear break up time(TBUT). A dry eye problem with contact lenses is often caused by the lid. If an incomplete blink is responsible for the dry eye it is possible to change the situation by blinking exercises. The result of these test, mean value of age was 22.8, mean value of blink rate was 19 times/min, mean value of Schirmer test was 25 mm/5 min, mean value of TBUT was 7.1 sec.

• Journal of the Korea Society of Computer and Information
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• v.23 no.2
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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.

• Smart Structures and Systems
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• v.21 no.6
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• pp.777-791
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• 2018

This paper discusses the shape control of deformable mirrors for Adaptive Optics in the dynamic range. The phenomenon of control-structure interaction appears when the mirror becomes large, lowering the natural frequencies $f_i$, and the control bandwidth $f_c$ increases to improve the performance, so that the condition $f_c{\ll}f_i$ is no longer satisfied. In this case, the control system tends to amplify the response of the flexible modes and the system may become unstable. The main parameters controlling the phenomenon are the frequency ratio $f_c/f_i$ and the structural damping ${\zeta}$. Robustness tests are developed which allow to evaluate a lower bound of the stability margin. Various passive and active strategies for damping augmentation are proposed and tested in simulation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.441-441
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• 2007

As Rhenium-Iridium{Re-Ir) coating possesses such features as, high hardness, high elasticity, abrasion resistance and chemical stability, there have been exerted continuous efforts in research works in a variety of fields, and this technology has also been applied widely to industrial areas. In this research, the optimal grinding condition was identified using Microlens Process Machine in order to contribute to the development of aspheric glass lens for mobile phone module having 3 mega pixel and 2.5X zoom, and molding core(WC) was manufactured having performed ultra-precision machining. Effects of Re-Ir coating on form accuracy (P-V) of molding core and surface roughness(Ra) were measured and evaluated.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.73-75
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• 2005

The latest scientific highlights obtained with the Subaru telescope are given together with its current status and on-going instrumentation. We have been successfully operating the telescope and 8 observatory instruments (including an adaptive optics system) since January 1999, when the first light was accomplished. Open-use of Subaru began in December 2000. Subaru has a unique capability of its prime focus among other 8-10 meter class telescopes and has an excellent imaging performance as a result of its sophisticated active optics combined with the high stability of the sky at Mauna Kea. Scientific highlights are given on the discoveries of the most distant galaxies, spiral structure on a protoplanetary disk around AB Aur, and planetesimal belts in the debris disk around $\beta$ Pic. Brief summaries are given for three new instruments: the Multi-Object Infrared Camera and Spectrograph (MOIRCS), 188 element adaptive optics system, and Fiber Multi-Object Spectrograph (FMOS)

• Current Optics and Photonics
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• v.4 no.6
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• pp.500-508
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• 2020

The rifling angle of artillery is an important parameter, and its determination plays a key role in the stability, hit rate, accuracy and service life of artillery. In this study, we propose an optical measurement method for the rifling angle based on angle error correction. The method is based on the principle of geometrical optics imaging, where the rifling on the inner wall of the artillery barrel is imaged on a CCD camera target surface by an optical system. When the measurement system moves in the barrel, the rifling image rotates accordingly. According to the relationship between the rotation angle of the rifling image and the travel distance of the measurement system, different types of rifling equations are established. Solving equations of the rifling angle are deduced according to the definition of the rifling angle. Furthermore, we added an angle error correction function to the method that is based on the theory of dynamic optics. This function can measure and correct the angle error caused by the posture change of the measurement system. Thus, the rifling angle measurement accuracy is effectively improved. Finally, we simulated and analyzed the influence of parameter changes of the measurement system on rifling angle measurement accuracy. The simulation results show that the rifling angle measurement method has high measurement accuracy, and the method can be applied to different types of rifling angle measurements. The method provides the theoretical basis for the development of a high-precision rifling measurement system in the future.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.1
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• pp.119-124
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• 2001

Dimethyl terephthalate (DMT). 1.4-butanediol (1.4-BD) and poly (tetramethylene ether) glycol (PTMG) in the molecular weight of 2000 (g/mol) were used to synthesize poly(ether-b-ester) thermoplastic elastomers (TPEEs). The final copolymers were annealed to improve thermal stability at elevated temperatures and mechanical properties. This study showed that as the proportion of soft segment increases melting temperature and degree of crystallinity of TPEEs decrease constantly. In case of mechanical properties like flexural strength and flexural elastic modulus. $35-PTMG^{2000}$ indicates the highest values due to more efficient physical interlock.