CR39 1.499 Single Vision Optical Lens Blanks , Anti Scratch Semi Finished Lens Blanks

 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.

CR39 Features:

1 ) . The better among other index lenses in hardness and toughness , high impact resistance .   2 ) . The more easily tinted than other index lenses. 3 ) . The higher transmittance as compared with other index lenses . 4 ) . The higher ABBE value providing the most comfortable visual experience .   5 ) . The more reliable and consistent lens product physically and optically .   6 ) . The more popular in the middle level countries .