• Journal of the Korea society of information convergence
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• v.6 no.2
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• pp.57-60
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• 2013

In this paper, We compared middle-aged wearer's satisfaction of progressive multifocal lens and free-form progressive multifocal lens wearers, and investigate the direction of improvement of progressive multifocal lens. We tried to predict the development direction of progressive lenses in the future. The results of the survey, satisfaction of free-form progressive multifocal lens wearers was high, compared to normal progressive lenses. The price of free-form progressive multifocal lens is expensive compared to the nomal progressive multifocal lens, but provides a wide view than nomal progressive lenses. It was confirmed that there is sufficient merit. because it can be made in individual customized to the wearer. In the near future, It is expected that free-form progressive multifocal lenses is the most popular progressive multifocal lenses to middle-aged wearers.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.2
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• pp.131-135
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• 2006

The purposes of this study is examining a wearing tendency of a progressive multifocal lens. We measured refractive error values using subjective and objective refraction method with subjects in 40-65 ages. Also, we investigated and analyzed distribution of addition power and wearing tendency of progressive multifocal lens. Detected addition powers were ranged of +0.75D - +3.00D. In case of average addition, they were detected with +1.18D in 40's, +1.55D - +1.97D in 50's and +2.38D in above 61's age. The distributions of visual ability at a distant were measured that the hyperopia and hyperopic astigmatism 43%, the myopia and myopic astigmatism characteristic astigmatism 7% appeared highly with 36%. The male who uses the interior aspect multi focal lens with the short-range work were appeared the male 20%, the woman 19%.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.07a
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• pp.557-560
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• 2020

최근, 광소자에서 공간 변조되는 wavefront profile 특성을 광소자의 표면 단차 변화 없이 단일 두께 박막 상에서 자유로이 구현할 수 있는 기하위상 홀로그램 (geometric phase hologram) 기반의 optical component에 대한 관심이 증대되고 있다. 특히 이를 이용해 제작된 기하위상 렌즈 (geometric phase lens)는 dynamic phase의 공간적 차이에 의해 구현되던 기존 bulk optics 기반의 lens 대비 초박형으로 제작이 가능한 파장 선택적 flat optics 기술로써, 다초점 및 경량화를 요구하는 차세대 디스플레이 기술 (augmented reality 또는 AR, mixed reality 또는 MR) 및 광파변조 및 제어를 요구하는 홀로그래픽 카메라 분야에 대한 응용처로 많은 주목을 받고 있다. 이에 본 논문에서는 해당 기하 위상렌즈에 대한 원리 및 이에 따른 개발이슈 및 해결법에 대해 연구 하였으며, 이에 대한 응용처로 기하위상 렌즈의 편광에 따른 이중초점특성을 이용해, 기존 단일 초점 형성이 가능한 AR기기 대비, 다초점 형성이 가능한 switchable dual-depth 3D AR device를 compact한 모듈과 함께 구현하였다. 또한, 기하위상렌즈의 광파 변조 및 분리특성을 이용한 기하위상 렌즈기반의 자가간섭 홀로그래픽 시스템(GP-self-interference incoherent digital holographic, GP-SIDH)에 편광 이미지센서 적용과 함께 맞춤형 설계/제작된 기하 위상렌즈를 적용함으로써, 기존 GP-SIDH 시스템대비 안정적으로 실시간 복소 홀로그램 획득이 가능한 실시간 공간영상정보 획득용 GP-SIDH을 동영상 프레임으로 구현하였다.

• The Optical Journal
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• s.121
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• pp.34-35
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• 2009

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.1
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• pp.103-108
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• 2009

Purpose: The objective of this study is to compare and analyze the wearing status of refractive error correction devices of elders who reside in a city or in a small town district. Methods: Each of opticians from a small town or a city was selected for the study of wearing status of presbyopia correction device for each residential district in units of percentage. with the analysis of the age and gender distributions of the elders, numbers of elderly members, and the kinds of presbyopia correction. Results: The wearing rate of progressive lens was reduced in reverse proportion to the increase of the age for the people of presbyopia in a twon. Pepople in 60s living in a town perferred to wearing bifocal lens, but people of 50~60s preferred to single vision lenses. However, none of people living in a city who is diagnosed as presbyopia had refractive error correction device, and no one used bifical lenses. The progressive lens was mostly used in the people of 40~50s and using rate of those lenses reduced with the age; and single vision lens had the highest rate of in the 40~50s but no one wore it in the 70s. Conclusions: Among the refractive error correction devices, the progressive lens was most widely worn by presbyopia group who is living in a town or a city. In particular, the refractive error correction devices were most preferred in 40~50s of early presbyopia. The highest preference for the progressive lens in the people with the early presbyopia indicates that the wearing rate of the progressive will be increased in future. Therefore, the opportunity of systematic education on the progressive lens should be increased.

• Korean Journal of Optics and Photonics
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• v.33 no.1
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• pp.28-34
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• 2022

We study through computational simulation the focal performance of an infrared (IR) Fresnel lens, composed of a multilayer-graphene zone plate formed under a graphene electrode. Here the Fermi level E_F of the patterned multilayer graphene is adjusted by the overlying graphene electrode. The Fresnel lens effect, with respect to the reflectance contrast between the graphene electrode and the 8-layer graphene zone plate placed on a glass substrate, has been analyzed over a broad wavelength range from 4 to 30 ㎛. As the optimal wavelength of 8 ㎛ (considering the reflectance and the reflectance-contrast ratio) is incident upon the Fresnel lens with a focal length of 240 ㎛, the focal intensity is enhanced by a factor of 4.3 as the E_F of multilayer graphene increases from 0.4 eV to 1.6 eV, and is improved by a factor of 5.8 as the number of graphene layers increases from two to eight. As a result, an all-graphene-based IR Fresnel zone-plate lens, exhibiting multifocal function (240 ㎛ and 360 ㎛) according to the selected E_F, is proposed as an ultrathin lens platform.

• Korean Journal of Optics and Photonics
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• v.20 no.6
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• pp.354-360
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• 2009

We have constructed and analyzed the performance of a simple fiber bundle multi-focal microscope. The microscope had a fiber bundle substituted for micro-lens array that is the core part of MMM(multi-focal multi-photon microscope). The MMM is a type of confocal microscope. To analyze the performance and characteristics of the fiber bundle multi-focal microscope, three types of samples were used: a standard grating, USAF 1951(7, 3), and 1951(7, 6). Using two polarizers and a polarizing beam splitter, we eliminated noise and got clear images. We obtained the FWHM of fiber spot images with the standard grating using two different magnifier lenses which were 63X and 20X, and found an image of the sample as a distribution of fiber spot images. For this case we used the low magnification lens, which gives denser distribution, so that we could get clearer images. In order to test the resolution of the fiber bundle multi-focal microscopic system, we used the USAF 1951 sample which has a smaller line interval than that of the standard grating. The FWHM of the line width of the image coincides well with the real line width of the USAF 1951 sample. We confirmed the performance of a fiber bundle multi-focal microscopic system which is relatively simple but has submicron resolution and is able to get 1600 images at the same time.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.487-491
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• 1994

최근에 광학을 기초로 한 산업계에서 중요시 되는 문제는 촛점을 자동으로 맞추는 문제다. 대부분 오토콜리케터(autocollimater)를 사용하여 수동으로 사람이 그 초점을 판별하여 맞추는 것이 현실이다. 하지만 산업계에서 이러한 작업을 필요로 하는 부분이 급성장하고 있으며 대량생산을 위해서는 자동화가 필수적으로 되어가고 있다. 특히 카메라 렌즈의 경우 최근 자동카메라의 급수요현상으로 조립시 카메라의 촛점을 맞추는 작업은 가장 기본적이고 정교한 작업이 되고 있다. 초점을 맞추는 것은 렌즈의 절대좌표를 지정하는 것으로 렌즈의 구동은 이 점을 기준으로 움직이게 된다. 본 논문에서는 초첨을 자동으로 맞추기 위한 작업으로 MTF(modulation transfer function)의 방법을 사용하였다. 일반적인 방법은 CCD(charge coupled device)를 사용하여 빛의 조도의 값을 비교하여 최대값이 나올때를 기준으로 하였으나, 모든 픽셀에 대한 계산을 행해야 하므로 시간이 오래 걸리게 되고 광원의 변화에 따라 민감하게 변화하는 단점을 가지고 있다. 그러나 MTF를 사용하면 아주 간단한 장치를 사용하고, 신호의 처리를 용이하게 하여 초첨의 거리를 쉽게 판단할 수 있다는 장점을 가지고 있다.

• Korean Journal of Optics and Photonics
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• v.26 no.3
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• pp.147-154
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• 2015

We propose a method for simultaneously measuring the front and back surface profiles of transparent optical components. The proposed method combines dual-wavelength transmission deflectometry with liquids to record distorted phases at different wavelengths, and then numerically reconstructs the three-dimensional phase information to image the front and back surfaces of the lens. We propose a theoretical model to determine the surface information, and a bifocal lens is experimentally investigated. Unlike conventional transmission deflectometry, our proposed method supports direct observation of the front and back surface profiles of the optical elements.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.41-45
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• 2002

To study the ametropia and the sort of glasses, especially progressive multifocal lens, for near purpose on Middle aged & Manhood. 500 adults were tested by the object and subject methods. Among the 500 adults, myopia is 22.4%, hyperopia is 61.4%, and emmetropia is 16.2%, respectively. In test of astigmatism, the amount of astigmatism for the age of forty one to under forty five with-the rule is 28%, the amount of astigmatism against-the rule is 43% and the amount of astigmatism with oblique is 11%, respectively. Whereas, the amount of astigmatism for the age of fifty six to under sixty with-the rule is 10%, the amount of astigmatism against-the rule is 71% and the amount of astigmatism with oblique is 19%, respectively. With-the-rule decreased with increasing age while against-the-rule increased with increasing age. The oblique astigmatism relationship to age could not be determined. The ratio of the progressive multifocal lens was 67.3% for male and 35% for female.