• Journal of Korean Ophthalmic Optics Society
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• v.14 no.3
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• pp.29-35
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• 2009

Purpose: To develop a relay lens type scope with 70 mm eye relief. Methods: By using Sigma 2000 design program, we designed and manufactured a relay lens type scope with 70 mm eye relief, which is integrated after designing an objective part with relay lenses and an eyepiece part, respectively. Results: The characteristics of the relay lens type scope with 70 mm eye relief whch is designed and manufactured by methods, which integrate after respectively designing an object part with relay lenses and an eyepiece part, have the magnification of $+4{\times}$,the length from 1st lens to last lens of about 105 mm, the barrel diameter of 18mm, and the effective diameter of 13 mm. Also we know that the resolution line width is 275 cycles/rad at the 30% MTF value criterion. Conclusions: We could design and manufacture the relay type scope with 70 mm eye relief, the characteristics of which have the magnification of $+4.0{\times}$the MTF above 30% at 275 cycles/rad, and the length from 1st lens to last lens of about 105 mm.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.9
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• pp.95-102
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• 2007

The scanning electron microscope (SEM) is one of the most popular instruments available for the measurement and analysis of the micro/nano structures. It is equipped with an electron optical system that consists of an electron beam source, magnetic lenses, apertures, deflection coils, and a detector. The magnetic lenses playa role in refracting electron beams to obtain a focused spot using the magnetic field driven by an electric current from a coil. A SEM column usually contains two condenser lenses and an objective lens. The condenser lenses generate a magnetic field that forces the electron beams to form crossovers at desired locations. The objective lens then focuses the electron beams on the specimen. The present work concerns finite element analysis for the electron magnetic lenses so as to analyze their magnetic characteristics. To improve the performance of the magnetic lenses, the effect of the excitation current and pole-piece design on the amount of resulting magnetic fields and their peak locations are analyzed through the finite element analysis.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.5 s.170
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• pp.80-86
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• 2005

Optical performance evaluation results and an interference fringe pattern analysis of alignment errors for an optical head of a near-field receding (NFR) system are presented. The focusing unit is an optical head of a NFR system and is composed of a solid immersion lens (SIL) and an objective lens (OL). Generally, the size of the focusing unit is smaller than that of the conventional optical recording head. Hence there are difficulties to assemble the small focusing unit precisely. We composed an evaluation system with an interferometer and evaluated some focusing unit samples aligned and assembled by manual and present the obtained results. Using the conventional optical tool, Code V, a tolerance analysis of the alignment error between the SIL and the objective lens and an interference pattern analysis for the assembly error are executed. Then, through an analysis of the simulation results, the conceptual auto-alignment methodology using a neural network approach is considered.

• Current Optics and Photonics
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• v.4 no.4
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• pp.330-335
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• 2020

We have investigated optimization of the working distance (WD) for a highly miniaturized imaging probe for endoscopic optical coherence tomography (OCT). The WD is the axial distance from the distal end of the imaging probe to its beam focus, which is demanded for dimensional margins of protective structures, operational safety, or full utilization of the axial imaging range of OCT. With an objective lens smaller than a few hundred micrometers in diameter, a micro-optic imaging probe naturally exhibits a very short WD due to the down-scaled optical structure. For a maximized WD careful design is required with the optical aperture of the objective lens optimally filled by the incident beam. The diffraction-involved effect was taken into account in our analysis of the apertured beam. In this study, we developed a simple design formula on the maximum achievable WD based on our diffraction simulation. It was found that the maximum WD is proportional to the aperture size squared. In experiment, we designed and fabricated very compact OCT probes with long WDs. Our 165-㎛-thick fiber-optic probes provided WDs of 3 mm or longer w ith reasonable OCT imaging performance.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.279-289
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• 2013

Purpose: To evaluate the changes of refractive power when worn soft contact lenses were temporarily removed. Methods: 91 soft contact lens wearers (15 males and 76 females; total 182 eyes) from 17 to 39 years of age (average: $24{\pm}4.8$ years) were participated. Objective and subjective refraction, and corneal radius were measured at 0, 30, 60 and 90 min after lens removal. The changes in refractive power were evaluated between measurements over time. The other parameters such as types of lenses, fitting and wearing conditions were also assessed. Results: Objective refraction, subjective refraction and corneal radius were significantly changed according to measured time (p<0.0001). A moderate myopic shifts was observed at the beginning (30 min after lens removal) and a slight myopic shift at the late of measurement (60 min to 90 min after lens removal). There are no significant differences between lens types, fitting states, wearing time, wearing days and sleeping time in the previous day. However, there was significant interaction in changes for corneal radius between measuring time and lens type (p=0.017), fitting state (p=0.019), and sleeping time prior to the test (p=0.010). Conclusions: Time to reach refractive and corneal radius stability after contact lens removal revealed at least more than 60 min, regardless of types of lenses, fitting and wearing conditions. Therefore, refraction for correction should be performed after waiting for more than that time as possible.

• Journal of the Ergonomics Society of Korea
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• v.31 no.1
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• pp.77-83
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• 2012

Objective: The aim of this paper is to introduce a method that can measure and analyze the judgment gaps between service providers and customers. Background: It is important to understand the good service that service providers and customers are thinking. If there is judgment gap between service providers and customers, it would cause an unsatisfactory service. The judgment gap should be thoroughly investigated for a good service design. Method: Lens model is a human decision making model that was proposed by Brunswick(1952). This study indicates whether the Lens model can be applied to analyze judgment gaps between service providers and customers. As a case study, a library lending service was selected. 5 librarians and 15 customers participated in the experiment that investigates their judgments on a good service. The obtained data were analyzed by a modified lens model. Results: Cue weighting policies of consumers and service providers were similar, except that consumers gave higher weight on tangibility than service providers. Service providers and consumers had a good knowledge on the service quality, but they could not well apply the knowledge to judge it. Conclusion: The lens model may be used to analyze judgment gaps between service providers and consumers in the other service areas. The decision cues that were used in this study can be changed, depending on the characteristics of the target service. Application: The method that is proposed in this study may help to investigate and analyze both consumers' and service providers' judgments on a variety of services.

• International Journal of Contents
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• v.6 no.4
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• pp.35-38
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• 2010

The current categorization of digital games is not objective and is unable to assess the latest and more complex digital games. Digital games need to be systematically categorized so that similarities and differences can be identified and analyzed. The fundamental characteristic of digital games is interactivity. This paper addresses the current categorization gaps through the lens of interactivity. Through this lens, a conceptual framework consisting of primary and corresponding participants and controlling characters is developed. Future research topics are then presented based on this framework.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.4
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• pp.411-417
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• 2005

The aim of this study was to investigate the ability for wearers in adapting to the Pure Vision contact lens. Methods: Subjects consisted of 78 university students who were analyzed by subjective and objective methods. During each day of use or extended wear, results relative to clinically adapt were analyzed over a period of one week. Results: 1. Visual function status Good 62.3%, Moderate 27.2%, Bad 10.6% 2. Side affects No sensation 76.12%, Moderate sensation 18.21%, Excessive sensation 6.5% 3. Lens handling ability Skillful 97.44%, Difficult 2.56% 4. Understanding Pure Vision lens characteristics 50.64% understood very well Conclusions: Most Pure Vision contant lens wearers had a good clinical response both subjectively and objectively but about one half did not understand fully the lens characteristics.

• Journal of KSNVE
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• v.11 no.1
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• pp.49-56
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• 2001

In this paper, two plant models, of which one is newly developed and the other one is the conventional one, of the focus servo system of DVD drive are presented and a two-degree-of freedom controller consisted of Inverse dynamics feedforward and LQG/LTR feedback controller is designed. The newly developed plant model is used to design the feedforward controller and the conventional model is used for the design of feedback controller. The output of newly developed model is the displacement of objective lens and the output of conventional model is the focus error of the DVD focus servo system. The displacement of the objective lens is estimated by the dynamics model of the DVD focus servo system. The disturbance rejection performance of the two-degree-of freedom controller is compared with that of an LQG/LTR one.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.386-389
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• 2003

Recent issues in Optical Disk Drive (ODD) are focused on small size. Blu-ray Disk (BD), using blue laser (405nm wavelength) and high NA (0.85) objective lens. can store 25Gbyte on a conventional 12cm optical disk. Small Form Factor Optical (SFFO) drive uses 3cm disk which can store 1.5Gbyte on a disk. This kind of Small Form Factot Optical (SFFO) drive correspond to PCMCIA type memory (Compact Flash or Micro Drive). Preferably, Optical Disk has relatively low cost of the storage media per Byte rather than PCMCIA type memory. To make Small Form Factor Optical (SFFO) drive. optical pickup and its component must be miniaturized. Miniaturization of the component needs new concept of Optical Pickup. This paper is focused on two main subjects. One is Objective Lens design which can be manufactured on a wafer, and the other is optical path design of the pickup which has 2mm thickness.