• Journal of Korean Ophthalmic Optics Society
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• v.4 no.2
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• pp.91-96
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• 1999

This study involves the research about relationship between visual charts and illumination. The subjects were both males and females in their teens and twenties. The examination instrument used was a B-VAT II BVS(Mentol) which was produced in the USA, and the illumination used was a low illumination of 100LUX and a high illumination of 1500LUX in the clinical examination room. The results were as follows: 1. Different types of illumination resulted in similar values of visual acuity. 2. In the male teen subjects, the Snellen visual acuity was better than the numerical visual acuity when using low illumination. But the Landolt visual acuity presented similar results when using both low and high illumination. 3. In male subjects in their twenties, the Numerical visual acuity was better than the Landolt and Snellen visual acuity under low illumination. 4. In the female teen subjects, The Snellen visual acuity was better than the Landolt and Numerical visual acuity under low illumination. 5. In the female subjects in their twenties, The Snellen, Landolt and numerical visual acuities were high under low illumination. 6. Different types of illumination resulted in 0.3 or 0.4 variation of visual acuity. 7. The males and females was similar to the visual acuity.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1341-1344
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• 2009

A novel method to control the viewing direction by moving aperture location in 4-f illumination optics to control light direction is proposed. Based on integral imaging principle, the relayed point light sources by 4-f optics are modulated by a spatial light modulator, displaying three-dimensional images. In the proposed method, we locate the aperture, which acts as a band pass filter, around an optic axis to control the light direction. Resultantly, assuming that we know the viewer position by a tracking system, we can display appropriate three-dimensional images over large viewing angle.

• Current Optics and Photonics
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• v.1 no.1
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• pp.23-28
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• 2017

The laser has been regarded as the potential illumination source for the next generation of projectors. However, currently the major issues in applying the laser as an illumination source for projectors are beam shaping and laser speckle. We present a compact solution for both issues by using a vibrating diffractive optical element (DOE). The DOE is designed and fabricated, and it successfully transforms the circular Gaussian laser beam to a low speckle contrast uniform rectangular pattern. Under a vibration frequency of 150 Hz and amplitude of $200{\mu}m$, the speckle contrast value is reduced from 67.67% to 13.78%, and the ANSI uniformity is improved from 24.36% to 85.54%. The experimental results demonstrate the feasibility and potential of the proposed scheme, and the proposed method is a feasible approach to the miniaturization of laser projection display illumination systems.

• Journal of the Optical Society of Korea
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• v.17 no.5
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• pp.376-383
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• 2013

The design of the LEDs lighting in general household illumination was proposed and compared with the fluorescent lighting in this study. Using the LED as a light source would promote energy saving lighting for household illumination purposes. We used the LightTools and DIALux software to design and simulate different standards of illuminance, different correlated color temperatures and different color rendering indices for household environments. The power consumption and efficiency of traditional illuminated light sources and an LED light source with the same standard of illuminance for lighting the household environment were analyzed and compared with each other. Finally, our results show the advantages of using white-light LEDs for lighting and household illumination.

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.745-751
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• 2016

A detection algorithm, based on the combined local-global (CLG) optical-flow model and Gaussian pyramid for a moving target appearing against a dynamic background, can compensate for the inadaptability of the classic Horn-Schunck algorithm to illumination changes and reduce the number of needed calculations. Incorporating the hypothesis of gradient conservation into the traditional CLG optical-flow model and combining structure and texture decomposition enable this algorithm to minimize the impact of illumination changes on optical-flow estimates. Further, calculating optical-flow with the Gaussian pyramid by layers and computing optical-flow at other points using an optical-flow iterative with higher gray-level points together reduce the number of calculations required to improve detection efficiency. Finally, this proposed method achieves the detection of a moving target against a dynamic background, according to the background motion vector determined by the displacement and magnitude of the optical-flow. Simulation results indicate that this algorithm, in comparison to the traditional Horn-Schunck optical-flow algorithm, accurately detects a moving target undergoing illumination changes against a dynamic background and simultaneously demonstrates a significant reduction in the number of computations needed to improve detection efficiency.

• Current Optics and Photonics
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• v.6 no.3
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• pp.332-336
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• 2022

Given a cubic space, it is easy to uniformly illuminate the floor with light sources placed on top. However, little has been reported about uniform illumination on walls with the same configuration of light sources. Here we present a luminaire consisting of nine light-emitting diodes (LEDs) with perfect Lambertian distribution, placed on the top as a 3 × 3 rectangular LED array. The distances between LEDs and tilt angles of each individual LED are adjustable and optimized by an annealing algorithm. After optimization, the array produces a rectangular illumination pattern on one wall with a uniformity of about 89%. Analysis shows that the tilt angles of individual LEDs are key parameters for uniform side illumination. In a scenario that is more practical, the tilt angles of all the LEDs are set to be the same, only decreasing the uniformity to 83%.

• Journal of the Semiconductor & Display Technology
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• v.11 no.3
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• pp.1-6
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• 2012

In this paper, inspection system based on optical scanning mechanism is designed and developed for solar cell wafer. It consists of optical scanning mechanism, NIR camera optics, machinery and control system, algorithm of defect detection and software. Optical scanning mechanism is composed of geometrical camera optics and structured hybrid illumination system. It is used to inspection of surface defects. NIR camera optics is used for inspection of defects inside solar cell wafer. It is shown that surface and internal micro defects can be detected in developed inspection system for solar cell wafer.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.1-4
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• 2000

The test of stereoacuity provides relatively accurate assessment of binocular functior. in the clinical fields. The purpose of this study was to investigate performance on the Random-dot E(RDE) stereotest under the binocular conditions by the difference of the illumination and test distance. The more light illumination increase. The more pass of RDE stereotest increase. On the other hand. On the near distance of test target. All subjects have a pass toe RDE stereatest. But On the far distance of test target. Some subjects have a pass the RDE stereatest. According to the test distance. The more far distance of test target. the less subjects have a pass the RDE stereotest. As a results, The RDE stereotest have effected the test distance and illumination.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.12
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• pp.1089-1093
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• 2013

Depth extraction using the structured illumination method is popularly applied since it has the benefit of measuring the object without contact. With multiple spatial frequencies and phase-shifting techniques, it is possible to extract the depth of objects with large discontinuity. For applications such as 3D (Three Dimensional) displays, 3D information of the object is required and is useful if corresponding to each view of the display. For this purpose, hypercentric optics is appropriate to measure the depth information of an object with a large field of view that is applicable for a 3D display. By experiment, we present the feasibility for phase-shifting profilometry using hypercentric optics to obtain the depth information of an object with the field of view appropriate for a 3D display.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.4
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• pp.549-554
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• 2013

Purpose: To determine the minimal illumination for visual acuity with the decimal vision chart and individual difference with varying contrast and illumination. Methods: Landolt's vision chart with 10 different grade of contrast was made. Minimal illumination was measured for 69 eyes using 100% contrast vision chart. Minimal contrast for identifying the chart was measured in conditions of the minimal illumination and 230 lx, respectively. Results: Minimal illumination was gradually increased with decrease of the chart size. Mean of minimal illumination to identify the 1.0 visual acuity was $74.39{\pm}25.90$ lx with range of 17~107 lx. In conditions of the minimal illumination and 230 lx, the minimal contrast for identifying the chart were gradually increased with decrease of the chart size in both conditions, the those deviation for 69 eyes was also increased. Conclusions: For refractive correction, examiners need to consider the individual difference for identifying the visual chart according to illumination and contrast.