• Journal of Korean Ophthalmic Optics Society
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• v.16 no.4
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• pp.391-401
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• 2011

Purpose: In the present study, the actual management state of trial contact lenses and lens care products in local optical shops was surveyed and analyzed to reduce the risk of lens complication possibly induced by neglecting lens care. Methods: The feeling of contact lens wearers during the wear of trial contact lenses was surveyed. Futhermore, the actual management state of trial contact lenses such as cosmetic lens and RGP lens and lens care products was also investigated by surveying opticians who trade contact lenses in local optical shops. Results: It was found that consumers trusted the sanitary conditions of the lens since trial cosmetic contact lens and RGP lens were cleaned before and after trails by over 98% of opticians in local optical shops. For trial cosmetic lens, cleaning with normal saline, multipurpose solution for soft lens and combination of saline and multipurpose solution were 38.5%, 40.5% and 21%, respectively, before trials. After trials, cosmetic lenses were cleaned with normal saline, multipurpose solution for soft lens and a combination of saline and multipurpose solution were 13%, 75%, and 12%, respectively. On the other hand, cleaning with normal saline, multipurpose solution for RGP lens and combination of saline and multipurpose solution were 28.5%, 38.5% and 33%, respectively, before trying trial RGP lens. After trials, RGP lenses were cleaned with normal saline, multipurpose solution for RGP lens and a combination of saline and multipurpose solution were 2.5%, 70%, and 27.5%, respectively, indicating that relatively many opticians followed the lens cleaning regimen. In local optical shops, the cleaning trial cosmetic lens was mainly conducted at every 10 days or a month and the washing cycle of cosmetic lens case was in a month or 2~3 months. The cleaning interval of trial RGP lens was primarily in a month or 2~3 months. For those lens cases, more than 75% of opticians washed them with a surfactant and then rinsed with cold water. The storing periods of lens care products were primarily in a week for saline and in a month and 2~3 months indicating that storing period of lens care products was relatively well-kept in local optical shops. Conclusions: It is thought that the concern about any microbial infection is not that high since trial contact lenses and lens care products were generally well-managed by opticians in local optical shops from the results above. However, better public eye health and better public confidence in opticians may be possible if further strengthen in avoidance of lens cleaning with saline, keep of cleaning cycles within 2 weeks and rinsing of lens cases with hot water happens.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.6
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• pp.472-476
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• 2019

We have proposed a novel planar lightwave circuit (PLC) optical sensor to monitor the contamination in a flow-cell where water is continuously supplied through a water quality measurement system. We designed a PLC chip with a V-shape waveguide and the simulated its function as a sensor for monitoring contamination in a flow-cell using a numerical the FDTD (finite-difference time-domain) analysis. A novel cross type of waveguide was introduced to make the PLC chip of the V-shaped waveguide. The fabricated PLC was cut into the cross waveguide. A change in the optical propagation loss of the PLC sensor was observed after immersing the PLC sensor into city water. It was determined that the propagation loss of the PLC sensor was 3 dB at a wavelength of $1.55{\mu}m$ in the city water for 15 days.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.217-224
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• 2005

A light-guide plate of an LCD backlight coupled with a microfresnel lens array (MFLA) is designed and analyzed. Computer simulated results of optical characteristics of our MFLA-type light-guided plate compared with the conventional prism-type one are presented. We show that the MFLA-type light-guide plate can replace well the conventional prism-type plate.

• Korean Journal of Optics and Photonics
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• v.34 no.6
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• pp.276-282
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• 2023

In this paper, we designed a lighting optical system using a freeform lens as a substitute for expensive gobo lighting. Unlike gobo lighting, freeform lens lighting does not use an image mask, and it can form and project an image directly on the lens surface using only a single lens, thus reducing the cost compared to gobo lighting. In order to verify the performance of freeform lens lighting with these advantages, we conducted an illuminance simulation. As a result, it was confirmed that it can replace gobo lighting because it has an illuminance distribution similar to the image we want to irradiate and a light efficiency of 47% similar to the performance of gobo lighting.

• Current Optics and Photonics
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• v.7 no.3
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• pp.273-282
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• 2023

This paper presents a new method for redistributing effectively the first orders of each lens element to achromatize and athermalize an optical system, by introducing a novel method for adjusting the slope of an achromatic and athermal line. This line is specified by connecting the housing, equivalent single lens, and aberration-corrected point on a glass map composed of available plastic and glass materials for molding. Thus, if a specific lens is replaced with the material characterized by the chromatic and thermal powers of an aberration-corrected point, we obtain an achromatic and athermal system. First, we identify two materials that yield the minimum and maximum slopes of the line from a housing coordinate, which specifies the slope range of the line spanning the available materials on a glass map. Next, redistributing the optical first orders (optical powers and paraxial ray heights) of lens elements by moving the achromatic and athermal line into the available slope range of materials yields a good achromatic and athermal design. Applying this concept to design a mobile-phone camera lens, we efficiently obtain an achromatic and athermal system with cost-effective material selection, over the specified temperature and waveband ranges.

• Korean Journal of Optics and Photonics
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• v.34 no.2
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• pp.66-71
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• 2023

Zoom lenses are now starting to be applied to mobile-phone cameras as well. A zoom lens applied to a mobile-phone camera is mainly used to capture images in the telephoto range. Such an optical system has a long focal length, similar to that of a high-magnification zoom optical system, so the position of the imaging device also shifts significantly, due to manufacturing errors of the lenses and mechanical parts. In the past, the positional shift of the imaging device was corrected by moving the first lens group and the total optical system, but this paper confirms that the position of the imaging device can be corrected by selecting any two moving lens groups. However, it is found that more distance must be secured in the front and rear of a moving lens group for this purpose.

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.20-21
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• 2005

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.34-35
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• 2000

In optical pick-up systems, it's important of the efficiency of lens. We had simulated and estimated the efficiency of micro fresnel lenses which designed according to various focal lengths and wave lengths. Also we had simulated and estimated the micro fresnel lenses with a step-shape which number of steps are 2, 4 and 7. Through studies on between step_shape and design factor, we have obtained a proper number of step-shape fresnel lens for manufacturing that.

• Journal of the Optical Society of Korea
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• v.19 no.1
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• pp.88-94
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• 2015

This paper reports the fabrication of a lenticular liquid crystal (LC) lens array with thermally tunable focus and with the function of a convertible lens type, using the surface structure of a UV-curable polymer and a twisted-nematic (TN) LC cell. The TN LC cell makes the LC lenticular lens function as a converging or diverging lens by controlling electrically the polarization of input light. Therefore, the focal lengths for both the converging and diverging lenses, which can be switched from the TN cell, can be tuned by changing the effective refractive index of the LC by Joule heating of the transparent electrode. As a result, the focal length of the lens with the E7 LC was changed continuously from 8.7 to 31.2 mm for the converging lens type and from -9.8 to -14.2 mm for the diverging lens when the temperature was increased from 25 to $56^{\circ}C$.

• Korean Journal of Optics and Photonics
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• v.28 no.2
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• pp.75-82
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• 2017

We present a new type of receiver-transmitter optical system that can be adapted to the sensor head of a displacement-measuring interferometer. The interferometer is utilized to control positioning error and repetition accuracy of a wafer, down to the order of 1 nm, in a semiconductor manufacturing process. Currently, according to the tendency of scale-up of wafers, an interferometer is demanded to measure a wider range of displacement. To solve this technical problem, we suggest a new type of receiver-transmitter optical system consisting of a GRIN lens-Collimating lens-Afocal lens system, compared to conventional receiver-transmitter using a single collimating lens. By adapting this new technological optical structure, we can improve coupling efficiency up to about 100 times that of a single conventional collimating lens.