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KMID : 1159320160180010041
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Korean Journal of Vision Science
2016 Volume.18 No. 1 p.41 ~ p.47
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Crack of Coating Film on Eyeglasses Lenses in Dry heat Environment
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Lee Hyun-Joo
Kim Heung-Soo
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Abstract
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Purpose: This paper examines a condition of crack of coating film depending on dry heat environment of eyeglasses Lenses.
Materials and Methods: Like the most commonly used lenses for eyeglasses, lenses have UV blocking, hard-surface, and anti-glare coatings with diopter -2.00 D., index 1.56, center thickness 1.22 mm, diameter 73 mm. To make the experiment, two different conditions are constructed. The average temperature of automobile interior environment at outdoor parking lots in summer(70℃) and that of public bath and sauna(90℃) are made respectively by applying dry-heat condition inside an electric oven. Then, lenses are placed in each state. There is periodical observation on crack of
coating film on eyeglasses Lenses with slit lamp microscope(SL-102, Zeiss, Germany), which is every five minute for total 20 minutes in the state of 70℃ and every three minute for total nine minutes in the state of 90℃ respectively. The result is analyzed by using photo-spectrometer (UV-2450, Shimadzu, Japan) to measure spectral transmittance and reflectance of 380 nm~780 nm visible light.
Results: In 70℃, a crack is found on the coating film during the initial 5.1 to 10 minutes. There is no crack during the first five minutes. In 90℃, a crack is always found on the coating film after the initial 1 minutes. That is to say, the initial crack occurs during the first 1.1 to 3 minutes in 90℃. As a crack on coating film gets bigger, spectral transmittance decreases and reflectance increases.
Conclusions: Eyeglasses located inside the car at summer outdoor parking lot(average 70℃), and people with eyeglasses inside the public bath, sauna and sweating bathroom(average 90℃) can be easily spotted these days. Given this reality, Eyeglasses wearer, possible damages on their eyeglasses need to be handled with great care. Furthermore, glasses wearers should be guided by more publications and educational resources on the basis of realistic and practical research.
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KEYWORD
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eyeglasses lenses, dry heat, coating film, Crack time of coating film, spectral transmittance, reflectance
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