--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.
---- 1.74 index lens.
1). Impact resistance: 1.74 high index lenses meet FDA standard, can pass the falling spere test, have higher resistance to scratches and impact
2). Design: It approaches flat base curve, can offer people amazing visual comfort and aesthetic appeal
3). UV protection: 1.74 single vision lenses have UV400 protection, that means full protection against UV rays, including UVA and UVB, protect your eyes everytime and everywhere.
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4) Higher index lenses bend light at a steeper angle than lesser index versions.
The ‘index’ is the result given as a number: 1.56,1.61,1.67 or 1.74 and the higher the number, the more light is bent or 'slowed down'. Therefore, these lenses have less curvature for the same focal power requiring less lens substance/material.
5). Aspherical shape: Aspherical lenses are thinner and lighter than spherical lenses, relieving the visual fatigue caused by oppression effectively. In addition, they also can reduce aberration and distortion, give people more comfortable visual effect.
6). Super Hydrophobic Coating: It also called crazil coating, can make the surface of the lenses super hydrophobic, smudge resistance, anti static, anti scratch, reflection and oil, etc.