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Edge Thickness Formula:
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Lens edge thickness is a critical measurement in optical lens manufacturing and fitting. It represents the thickness of a lens at its periphery, which is calculated by adding the center thickness to the sagitta difference between the front and back surfaces of the lens.
The calculator uses the edge thickness formula:
Where:
Explanation: This calculation helps opticians and lens manufacturers determine the final edge thickness of a lens, which affects both the aesthetic appearance and practical fitting of eyeglasses.
Details: Accurate edge thickness calculation is essential for proper lens fitting, cosmetic appearance, and ensuring the lens can be properly edged and mounted into frames. It also helps in predicting the final weight and thickness of prescription lenses.
Tips: Enter the center thickness and sagitta difference in millimeters. Both values must be positive numbers. The calculator will provide the total edge thickness measurement.
Q1: Why is edge thickness important in lens selection?
A: Edge thickness affects the cosmetic appearance of glasses, the weight of the lenses, and determines if lenses can be properly fitted into certain frame types.
Q2: What factors influence lens edge thickness?
A: Prescription strength, lens material, base curve, lens diameter, and frame size all contribute to the final edge thickness.
Q3: How can I reduce edge thickness in high-prescription lenses?
A: Using high-index materials, aspheric designs, proper frame selection, and optical center placement can help minimize edge thickness.
Q4: What is considered acceptable edge thickness?
A: While subjective, most opticians aim for edge thickness under 5-6mm for aesthetic reasons, though this varies based on prescription and frame style.
Q5: Does edge thickness affect lens durability?
A: Extremely thin edges may be more prone to chipping, while very thick edges can make lenses heavy and difficult to fit properly in frames.