Q. What's semi-finished lens for? A. 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.
Q. What's the importance of a good semi finished lens to RX production? A. a. High qualified rate in power accuracy and stability b. High qualified rate in cosmetics quality c. High optical features d. Good tinting effects and hard-coating/AR coating results e. Realize the maximum production capacity f. Punctual delivery
Q. What's the most important parameters in regards of semi-finished lenses?
A: Before put the semi-finished lenses into RX process, we must make it clear about several data, such as Radius, Sag, True curve, Tooling index, Material index, CT/ET, etc.
Front/Back Radius: A stable precise radius value is very important to the power accuracy and consistency.
True Curve: The correct and precise true curve (not nominal curve) is very important to the power accuracy and consistency.
CT/ET: The center thickness and edge thickness affect the RX production range
Index: Correct material index and tooling index are both very important to get an accurate power.
Rather 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. Freeform lab requests for high quality of semi-finished lenses in precise and stable base curves / radius / thickness. Unqualified semi-finished lenses will lead to much waste in capacity, labor, clicking charge, delivery postpone, the consequence of which will be more than the semi-finished lens cost.