|CR39 1.499 Semi Finished Lens|
|Material: 1.499 Index Resin(Ne=1.50, Abbe value=57, Specific gravity=1.33 )|
|Production||1.499 semi finished single vision lens|
|Guarantee years||5 years|
|Power range||Base: 50~1000|
Semi Finished Lens:
The starting point for freeform production is a semi-finished lens, also known as a puck due to its resemblance to an ice hockey puck. These are produced in a casting process that is also used to manufacture stock lenses. The semi-finished lenses are produced in a casting process. Here, liquid monomers are first poured into moulds. Various substances are added to the monomers, e.g. initiators and UV absorbers. The initiator triggers a chemical reaction that leads to hardening or "curing" of the lens, while the UV absorber increases the UV absorption of the lenses and prevents yellowing.
1 ) . The better among other index lenses in hardness and toughness , high impact resistance .
2 ) . The more easily tinted than other index lenses.
5 ) . The more reliable and consistent lens product physically and optically .
6 ) . The more popular in the middle level countries .
|Hard Coating is also named anti-scratch coating, can protect uncoated lenses from impact and scratch resistance.|