Lens'types
Optical frames are necessary to us,whether you are students or old people!
And lens are one of the most important of these components,how do we to distinguish them?
There 're four kinds of lens that we shall learn about:
1)Glasses lens:
Advantage:the hardness is high,scratch-resistant;high definition;
Disadvantage:the difference in color image is quite large,easy lead to the decrease of peripheral vision.
This lens are applicable for office business type instead of outdoor sports activity!
2)PC lens
This lens are solid in state,the major component is polycarbonate,belongs to heat shrinkable materials.
Advantage:light and safety since it's not easy to break.
Disadvantage:it's hard to process ,and there will a big possiblity to be scratched!
It is widely used to rimless frames,flat galsdses ,and hardly to apply to optcial frame.
3)Resin lens
This lens are liquid which is the most widely used good quality ones.
The advantage is it has light weight,reduce the pressure of wearing glasses.
Disadvantage is abrasion resistance is poor,easy to be scratched,the index of refraction is low.
4)Natural lens material
This material is made from fine ground quartz.
Advantage:The hardness of the material is relatively large
Disadvantage:It can not totally absorbed sun shine ultraviolet.
This material is eliminated now!
