Progressive lenses are line-free multifocals that have a seamless progression of added magnifying power for intermediate and near vision.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. Tags: 1.56 progessive lens,1.56 semi-finished lens
3）Minus and plus semi-finished lenses ①Lenses with different dioptric powers can be made from one semi-finished lens. The curvature of the front and back surfaces indicates whether the lens will have a plus or minus power. ②Semi-finished lens is the raw blank used to produce the most individualized RX lens according to the patient's prescription. Different prescription powers request for different semi-finished lens types or base curves. ③Rather than just the cosmetic quality, semi-finished lenses are more about the inner quality, such as precise and stable parameters, especially for the prevailing freeform lens.