• Current Optics and Photonics
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• v.4 no.5
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• pp.441-445
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• 2020

A novel design for a Fresnel lens for a solar end-pumped laser is demonstrated in this paper. The new hybrid Fresnel lens includes two parts, inner and outer. The inner part is a twice-total-internal-reflection and vertical-transmission lens. The outer part is a once-total-reflection and vertical-transmission lens. The radius of the Fresnel lens is 600 mm, and its focal length is 750 mm. The concentrating performance of the Fresnel lens is examined using TracePro. The results show that the concentration efficiency has been greatly improved. The total concentration efficiency of the hybrid Fresnel lens reaches 73.2% when the radius of the laser rod is 3 mm. This design can simplify the concentration system of a solar end-pumped solid-state laser.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.1
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• pp.107-116
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• 2011

Purpose: The review article was written to establish an excel program that could calculate minimal Dk of contact lens without $O^2$ deficiency and actual $O^2$ concentration on cornea when contact lens were being fitted by changing lens-related factors. Methods: An excel program was formulated to calculate the thickness of post-lens lacrimal layer, Dk of contact lens and $O^2$ concentration on cornea. Results: With the excel program established, minimal $O^2$ concentration needed on cornea could be calculated when the thickness of post-lens lacrimal layer was changed by varying lens-related factors. A different route in the excel program was needed to choose based on the shape of lacrimal layer. The thickness of lacrimal layer was determined by the shape of meniscus made of tear between lens edge and cornea with flat fit. Thus, the $O^2$ concentration showing negative number in calculation decreased on peripheral cornea with flatter fitting and actual $O^2$ concentration would be zero on cornea. With tight fitting, the thickness of post-lens lacrimal layer is much thicker than lens itself thus negative number in calculation by the excel program is shown indicating zero oxygen on cornea. It can cause $O^2$ deficiency regardless of Dk of contact lens. Conclusions: The calculation of thickness of post-lens lacrimal layer and $O^2$ concentration on cornea by the established excel program is suggested to avoid $O^2$ deficiency when fitting state is varied by changing lens-related factors.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.27-33
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• 2011

HCPV(High Concentrated PV) systems have well known for CPV market all over the world. Low concentration type silicon based modules have been introduced in the market. But low cost of standard flat silicon modules made them useless nowadays. High cost of compound semiconductor solar cell reduced cost effective cpv module production than that of recently silicon solar cell. In order to overcome increasing cost of CPV module, we study middle concentration type fresnel lens simulation using concentrated type silicon based solar cell. Linear type fresnel lens made production of CPV module without secondary optics such as light pipe or light tunnel. This type of fresnel lens design makes more cost effective solution for cpv niche market.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.283-289
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• 2014

A Fresnel lens is an optical component which can be used as a cost-effective, lightweight alternative to conventional continuous surface optics. Fresnel lens solar concentrators continue to fulfill a market requirement as a system component in high volume cost effective Concentrating Photovoltaic (CPV) electricity generation. The basic principles of the fresnel lens are reviewed and some practical examples are described. To investigate the performance space of the Fresnel lens, a fast simulation method which is a hybrid between raytracing and analytical computation is employed to generate a cache of simulation data. Injection molders are warming up to the idea of cycling their tool surface temperature during the molding cycle rather than keeping it constant. Heat and cool process are now also finding that raising the mold wall temperature above the resin's glass-transition or crystalline melting temperature during the filling stage and product performance in applications from automotive to packaging to optics. This paper deals with the suitability of Fresnel lenses of imaging and non-imaging designs for solar energy concentration. The concentration fresnel lens confirmed machinability and optical transmittance and roughness measure through manufactured the prototype.

• New & Renewable Energy
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• v.5 no.3
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• pp.26-31
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• 2009

Using MBE growth method, GaAs/AlGaAs solar cell structure was grown. Deposited electrodes are Au/Ni/Ge for n-type and Au/Pt/Ti for p-type electrodes were deposited by E-beam evaporator. Indoor light concentrators were devised and fabricated in order to concentrate artificial solar rays. Also mirror and prism and Fresnel lens concentration system with solar simulator were devised and fabricated. Results of solar cell characteristics were measured with shutting system which can control the amount of light. Maximum power density was 2.13 W/$cm^2$ and maximum concentration was 124 sun, when mirror with Fresnel lens was used at $7854\;mm^2$ of shutter hole.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.1
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• pp.23-30
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• 2014

Purpose: The present study was aimed to figure out the correlation amongst the evaluation methods for critical micelle concentration, surface tension and protein cleaning efficacy to evaluate cleaning efficacy of contact lens care products. Methods: The critical micelle concentration of surfactants and the actual concentration of surfactants in contact lens care solutions were investigated by employing references published and related information. Surface tension of contact lens care solutions was measured by surface tension device at $25{\pm}1^{\circ}C$, and contact lenses made of lotrafilcon A, comfilcon A and balafilcon A were washed with contact lens care solutions after the incubation in artificial tears for 14 days and their cleaning efficacy was compared. Results: Among the 22 contact lens care products, 9 products provided the label of the concentration of surfactant, and 7 products showed higher concentration of surfactant than the critical micelle concentration reported in references. As a result of measuring surface tension, the surface tension of lens care products for soft contact lens was generally lower than other care products. When examined the removal effect of protein deposited on lens surface, it was known that the care products having lower surface tension showed higher protein removal efficiency. Conclusions: The surface tension is low when surfactant concentration in contact lens care solutions is high, and the removal effect of protein deposited is accordingly increased with the decrease of surface tension. Thus, these indicate the correlation amongst the evaluation methods for cleaning efficacy.

• Archives of Pharmacal Research
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• v.11 no.4
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• pp.312-314
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• 1988

Thirteen monoterpenes were examined for their effects on the bovine lens aldose reductase activity. the monoterpenes tested in this study showed mild inhibitory effects except 3-carene which did not show any significant effect. At the concentration of $10^{-3}$ M(+) Pulegon showed 42% inhibition on lens aldose reductase activity, which is the most otent effect among the tested substance.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.3
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• pp.45-50
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• 2008

Purpose: A soft contact lens was manufactured by adding naringin known as natural anti-bacterial material to resin solution. With solution eluted from manufactured contact lens, we examined its optical properties, physical and chemical states of naringin in the polymer, and elution properties. Methods: The soft contact lens with naringin was synthesized by bulk polymerization method. IR spectrum and HPLC were used to define the bonding type of naringin itself in the soft contact lens contained naringin, elution process of naringin to the saline solution, and the amount of naringin solution eluted from the lens with elapsed time. Results: Naringin was continuously eluted with constant concentration from the soft contact lens for about a month and the structure ofnaringin which is eluted was as same as before it was added to resin solution. Any change in optical properties such as transmittance couldn't be found. Bonding state and the structure of naringin in contact lens were explained with IR spectrum and HPLC results. Conclusions: In the contact lens with naringin, naringin remained in the contact lens bonding with weak hydrogen bonding and/or van der Waals force between naringin and polymer. Naringin was continuously eluted from the contact lens contained naringin during about 1 month. Even after 1 month, it showed that the concentration of the naringin eluted was approximately 10 ppm in a day. From the results, adding naringin to the soft contact lens resin is very effective method for manufacturing the soft contact lens which has anti-bacterial function for a period of time.

• Journal of Biomedical Engineering Research
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• v.17 no.3
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• pp.291-296
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• 1996

Poly(ethylene glycol)(PEG) macromers terminated with diacrylate Iyoups and interpenetrating poly- mer networks(IPN) composed of poly(hydroxyethyl methacrylate)(PHEMA) or poly(hydroxyethyl methacrylate-co-hydronypropyl methacrylate-co- N-vinyl pyrrolidone ) [ P( HEM A-co- HPM A-co- NVP) ] and PEG macromer were synthesized with the aim of obtaining protein adsorption resistant soft contact lens. Polymerization of PEC macromer resulted in the formation of cross-linked gels due to the multifunctionality of macromer. Crosslinked P(HEMA) or P(HEMA-co-HPMA-co-WVP) chains were interpenetrated into the cross-linked three-dimensional networks of PEG. It was found that albumin adsorption onto the contact lens prepared by P(HEMA-co-HPMA-co-NVP) /PEG IPW decreases with an increase of molecular weight of PEG. Also, it was found that albumin adsorption onto the both contact lens decreases with an increase of concentration of PEC macromer in the IPN preparation. There are also more adequate in the bioinertnen for the contact lens by P(HEMA)/PEG IPN or P (HEMA-co-HPMA-co-NVP)/PEG IPN than that by P(HEMA) or P(HEMA-co-HPMA-co-NVP)

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.4
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• pp.403-408
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• 2011

Purpose: To study the concentration distribution and diffusion depth in tinted lenses using the law of diffusion. Methods: The measured values taken from experiments were fitted with the theoretical fitting curve induced on the basis of Fick's second law of diffusion. Results: The fitting curves were in very good agreement with the measured values. As the results, we found the quantitative relationship between mass of dye solution diffused into the tinted lens per unit area and dyeing time, and evaluated concentration distribution of dye in tinted lens, diffusion depth, etc. Conclusions: The dyeing mechanism of tinted lenses can be well described by diffusion theory.