• Korean Journal of Materials Research
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• v.28 no.12
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• pp.685-690
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• 2018

In this study, a multifunctional ophthalmic lens material with an electromagnetic shielding effect, high oxygen permeability, and high water content is tested, and its applicability is evaluated. Metal oxide nanoparticles are applied to the ophthalmic lens material for vision correction to shield harmful electromagnetic waves; the pyridine group is used to improve the antibacterial effect; and silicone substituted with urethane and acrylate is employed to increase the oxygen permeability and water content. In addition, multifunctional tinted ophthalmic lens materials are studied using lens materials with an excellent antibacterial effect (2,6-difluoropyridine, 2-fluoro-4-pyridinecarboxylic acid) and functional (UV protection, high wettability) lens materials (2,4-dihydroxy benzophenone, 2-hydroxy-4-(methacryloyloxy)benzophenone). To solve problems such as air bubbles generated during the polymerization process for the manufacturing and turbidity of the lens surface, polymerization conditions in which the defect rate is minimized are determined. The results show that the polymerization temperature and time are most appropriate when they are $110^{\circ}C$ and 40 minutes, respectively. The optimum injection amount of the polymerization solution is 350 ms. The turbid phenomenon that appears in lens processing is improved by 10 to 95 % according to the test time and conditions.

• Korean Journal of Materials Research
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• v.34 no.7
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• pp.315-320
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• 2024

In order to maximize the function and increase the compatibility of silicone hydrogel lens, this study compared and analyzed the properties of Amino modified silicone oil using mini and microemulsion technique, respectively. Optical and physical properties were evaluated by spectral transmittance, refractive index, water content, oxygen transmittance and contact angle measurements to evaluate the performance of the manufactured hydrogel lens. The spectral transmittance results revealed the copolymerization method lens showed 31 % of the visible light area, which did not satisfy the basic optical properties. However, the lens using the mini and microemulsion materials showed more than 90 % of the visible light area, satisfying the optical characteristics. In addition, all physical properties were superior to a basic hydrogel lens. The mini and microemulsion techniques effectively improved the stability and function of the ophthalmic hydrogel lens and are considered a promising ways of manufacturing an ophthalmic hydrogel contact lens with increased compatibility and stability.

• Korean Journal of Materials Research
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• v.31 no.8
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• pp.427-432
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• 2021

This study uses silicone monomer, DMA, crosslinking agent EGDMA, and initiator AIBN as a basic combination to prepare hydrogel lenses using fluorine-based perfluoro polyether and iron oxide and zinc oxide nanoparticles as additives. After manufacturing the lens using iron oxide nanoparticles and zinc oxide nanoparticles, the optical, physical properties, and polymerization stability are evaluated to investigate the possibility of application as a functional hydrogel lens material. As a result of this experiment, it is found that the addition of the wetting material containing fluorine changes the surface energy of the produced hydrogel lens, thereby improving the wettability. Also, the addition of iron oxide and zinc oxide nanoparticles satisfies the basic hydrogel ophthalmic lens properties and slightly increases the UV blocking performance; it also increases the tensile strength by improving the durability of the hydrogel lens. The polymerization stability of the nanoparticles evaluated through the eluate test is found to be excellent. Therefore, it is judged that these materials can be used in various conditions as high functional hydrogel lens material.

• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.531-536
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• 2015

This paper presents a new graphical method for selecting a pair of optical glass and housing materials to simultaneously achromatize and athermalize a multilens system composed of many elements. To take into account the lens spacing and housing, we quantify the lens power, chromatic power, and thermal power by weighting the ratio of the paraxial ray height at each lens to them. In addition, we introduce the equivalent single lens and the expanded athermal glass map including a housing material. Even though a lens system is composed of many elements, we can simply identify a pair of glass and housing materials that satisfies the athermal and achromatic conditions. Applying this method to design a black box camera lens equipped with a 1/4-inch image sensor having a pixel width of $2{\mu}m$, the chromatic and thermal defocusings are reduced to less than the depth of focus, over the specified ranges in temperature and frequency.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.119-126
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• 2012

Purpose: To study changes in coating and lens materials after chemically etched different polymer based glass lenses in short-term and ambient condition using hydrofluoric acid. Methods: Vinyl ester polymer (Lens A) and thiourethane polymer (Lens B), both dyed in gray 70%, were etched in hydrofluoric acid solution for 5, 10, or 15 min. The mechanical properties, degrees of damages in hard coating, anti-reflection coating, and other coatings, rates of refractive index and light transmission of both polymer types were evaluated. Results: Rates of refractive index of both lens types were not changed significantly after chemical etching. However, anti-reflection coatings and hard coatings were removed and lens surfaces were damaged. As a results, UV light transmission of lenses increased and mechanical properties decreased. Chemical etching notably changed various properties of thiourethane polymer materials. Conclusions: Depending on types of polymer materials, chemical reactions by hydrofluoric acid were dissimilar. Thus, various properties of les materials were altered differently.

• Korean Journal of Materials Research
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• v.28 no.8
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• pp.452-458
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• 2018

This research is conducted to create a functional hydrogel ophthalmic lens containing nanoparticles. Carbon nanoparticles and PEGMEMA are used as additives for the basic combination of HEMA, MA, and MMA, and the materials are copolymerized with EGDMA as the cross-linking agent and AIBN as the thermal initiator. The hydrogel lens is produced using a cast-mold method, and the materials are thermally polymerized at $100^{\circ}C$ for an hour. The polymerized lens sample is hydrated in a 0.9 % saline solution for 24 hours before the optical and physical characteristics of the lens are measured. The refractive index, water content, contact angle, light transmittance, and tensile strength are measured to evaluate the physical and optical characteristics of the hydrogel lens. The refractive index, water content, contact angle, UV-B light transmittance, UV-A light transmittance, visible light transmittance, tensile strength and breaking strength of the hydrogel lens polymer are 1.4019~1.4281, 43.05~51.18 %, $31.95{\sim}68.61^{\circ}$, 21.69~58.11 %, 35.59~84.26 %, 45.85~88.06 %, 0.1075~0.1649 kgf and 0.1520~0.2250 kgf, respectively. The results demonstrate an increase in refractive index, tensile strength and breaking strength and a decrease in contact angle and light transmittance. Furthermore, the visible light transmissibility is significantly increased at PEG 10 %. It is clear that this material can be used for high-performance ophthalmic lenses with wettability, ultraviolet ray blocking effect, and tensile strength.

• ETRI Journal
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• v.31 no.6
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• pp.695-702
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• 2009

We propose a lens-drive unit composed of an ionic polymer-metal composite (IPMC) for an auto-focus compact camera module in cellular phones to solve the power consumption problem of voice coil motors which are widely used in commercial products. In this research, an IPMC incorporated into a lens-drive unit is designed to implement a large displacement in low-power consumption by using an anisotropic plasma treatment. Experimental results show that a camera module containing IPMCs can control and maintain the position of the lens by using proportional integral derivative control with a photo-reflective position sensor despite the non-linear actuation behavior of IPMCs. We demonstrate that the fabrication and commercialization of a lens actuator that has a large displacement and low power consumption using IPMCs is possible in the near future.

• Microbiology and Biotechnology Letters
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• v.37 no.1
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• pp.75-79
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• 2009

In this study, we polymerized new materials for soft contact lens using HEMA (2-hydroxyethyl methacrylate) which is the based-monomer of soft contact lens, EGDMA (ethylene glycol dimethacrylate) as cross linkage agent, and the new additives of monoester or di-ester derived from itaconic acid commercially produced by the fermentation of Asp. itaconicus. New polymer materials for soft contact lens were synthesized with the mixture of HEMA and mono- or diester at different ratios and presented to a good water content and oxygen transmissibility (Dk/L) values. In case of polymerization with HEMA and mono-ester (15%), the water content and oxygen transmissibility of contact lens were found to be good values at 57.6% and 28.5 Dk respectively. The mixture of HEMA and mono-ester is more excellent than HEMA/di-ester in the water content and oxygen transmissibility. The toxicity of new contact lens materials were confirmed in the fibroblast L-929 cell line using a agar overlay test and a growth inhibition test with the extract solution of contact lens.

• Korean Journal of Materials Research
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• v.29 no.12
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• pp.735-740
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• 2019

The purpose of this study is to fabricate an ophthalmic lens by copolymerizing two types of carbon nanotubes and hydrophilic hydrogel lens materials, and to investigate its application as an ophthalmic lens material by analyzing its physical properties and antimicrobial effect. For polymerization, HEMA (2-hydroxyethyl methacrylate), EGDMA (ethylene glycol dimethacrylate), a crosslinking agent, and AIBN (azobisisobutyronitrile), an initiator, are used as a basic combination, and a single-walled carbon nanotube and a single-walled, carboxylic-acid-functionalized carbon nanotube are used as additives. To analyze the physical properties, the water content, refractive index, breaking strength, and antimicrobial effect of the fabricated lenses are measured. The fabricated lenses satisfies all the basic properties of the basic hydrogel ophthalmic lens. The water content increases with increasing amount of additive and decreases with addition of 0.2 % ratio of nanoparticles. The refractive index is inversely proportional to the water content result. As a result of the antimicrobial test of the fabricated lens, the addition of carbon nanotubes shows an excellent antimicrobial effect. Therefore, it is considered that the fabricated lens can be applied as a functional material for basic ophthalmic hydrogel lenses.

• Korean Journal of Materials Research
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• v.32 no.12
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• pp.515-521
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• 2022

Various types of optical materials and devices used in special environments must satisfy durability and optical properties. In order to improve the durability of zinc sulfide multispectral (MS ZnS) substrates with transmission wavelengths from visible to infrared, Ge-Sb-Se-based chalcogenide glass was used as a sealing material to bond the MS ZnS substrates. Wetting tests of the Ge-Sb-Se-based chalcogenide glass were conducted to analyze flowability as a function of temperature, by considering the glass transition temperature (T_g) and softening temperature (T_s). In the wetting test, the viscous flow of the chalcogenide glass sample was analyzed according to the temperature. After placing the chalcogenide glass disk between MS ZnS substrates (20 × 30 mm), the sealing test was performed at a temperature of 485 ℃ for 60 min. Notably, it was found that the Ge-Sb-Se-based chalcogenide glass sealed the MS ZnS substrates well. After the MS ZnS substrates were sealed with chalcogenide glass, they showed a transmission of 55 % over 3~12 ㎛. The tensile strength of the sealed MS ZnS substrates with Ge-Sb-Se-based chalcogenide glass was analyzed by applying a maximum load of about 240 N, confirming its suitability as a sealing material in the far infrared range.