|1.74 High Index Semi Finished Aspherical Lens|
|Material: 1.74 Index Resin(Ne=1.738, Abbe value=33, Specific gracity=1.34)|
|CONVEX SURFACE||CONCAVE SURFACE|
|Mominal Curve||True Curve||Sag(sagitta: 40mm)||Sag(sagitta: 50mm)||Radius||Radius||CT(mm)||ET(mm)||Dia(mm)|
Semi finished lens:
The definition of semi finished lens
Semi-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.
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 advantages of high index lens:
Semi finished lens can be reprocessed to finished lens, and the prescription can according to your requirement. As 1.74 finished lens, there are several advantages for your reference.
1. High index lenses are thinner:
High index lenses are much thinner due to their ability to bend light.
As they bend light more than an ordinary lens they can be made much thinner but offer the same prescription power.
2. High index lenses are lighter:
As they can be made thinner, they contain less lens material and are therefore much lighter than ordinary lenses.
These benefits will increase the higher the index lens option selected. The more the lens bends light, the thinner and lighter it will be.
3. Impact resistance: 1.74 high index lenses meet FDA standard, can pass the falling spere test, have higher resistance to scratches and impact
4. Design: It approaches flat base curve, can offer people amazing visual comfort and aesthetic appeal
5. 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.
6. 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.