The main ingredient of such material is silicon dioxide, usually colorless and tinted in two ways. The material easy to wear, small thermal expansion coefficient. Because of its UV with unique transparency, ease of Visual fatigue caused by worn when. In
addition, because the Crystal density of this material is not uniform,
the lens often contains impurities, prone to when using double
refraction.
Glass lens
Main material is the production of lenses, is divided into the following five categories:
1, thanks to Lectra (Toric)
This
lens is also known as the white tray, white tablets, optical white
tablets, whose basic ingredient is sodium titanium silicate, colorless,
higher definition, 330A-absorbing UV radiation. Bai Tuo added Ceo2, Tio2 prevents ultraviolet 346A, also known as the UV white tablets. Its visible light penetration rate of 91-92%, refractive index of 1.523.
2, Crocker
Commonly known as ' chip, light transmission rate of 87%. A
two-color effect such lenses, in pale blue under sunlight (also known
as the blue-chip), pale red under incandescent (neodymium-containing
metals), absorbable 340A part following ultraviolet, infrared and
visible 580A yellow.
3, Crocker race
Commonly known as the gram game, add Ceo2 and Mno2 in Bai Tuo lens materials can improve the ability of ultraviolet absorption. This lens is pale red in daylight and incandescent, it is also known as the red. It to 350A ultraviolet absorption, light transmission rate of 88% per cent.
4, super thin slices
Such lenses in the raw material, add Tio2, Pbo, the refractive index increase of 1.7 per cent. Its
high reflectivity on the surface, than the ordinary one diopter of
white or red stacks of thin one-third, suitable for wear in high myopia,
aesthetic appearance. Due to the low Abbe
Number, color aberration, super thin slices can easily lead to lower
peripheral vision, color appears when the line curves.
, 5 glass lens
The
refractive index of the lens as 1.6, compared with ordinary glass
lenses (1.523) thinner, and relatively thin lenses (1.7) the proportion
of smaller, so it is very light, ideal for the wearer, some
manufacturers call it super light and super thin lenses.
According to the different face shapes to select different glasses
Square
Square face and short, jaw lines stand out, and have sharp corners. We need to be aware of the two features is a square face: short. Use a round frame, in particular, is round at the bottom of the frames can reduce the felt edges is too obvious.
"Long" faces two options:
1.
this method is most important: select the height small frame, frame
height is too large will face most and make people feel that face
shorter;
2. If possible, select mirrors the feet higher on the frame, will make the face look longer."sdwwwssa3xg"
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