How Lenses Are Made - Part 3
Surfacing
Once we receive your order, the journey to a finished pair of glasses begins in our surfacing department. Here is where the prescription is cut into the lenses.
From Lens Blank to Prescription Lens
We start with a lens blank, attaching it to a fixture with a medium like wax or alloy. This allows our machines to hold the blank securely as it moves through the process.
Unlike the glass molds we make in another part of our lab, surfacing lens blanks doesn’t require diamond tools because these blanks are made from softer materials like polycarbonate or plastic.
Cutting the Prescription
The generator then cuts the prescription directly into the back of the lens. At this stage, the lenses look frosted as they're covered with fine scratches. To bring them to optical clarity, we put them through polishing where abrasive pads and polishing compounds smooth the surface until the lens is crystal clear.
After polishing, the lens is de-blocked and prepared for its protective coatings.
Traditional vs. Digital Surfacing
Traditional Surfacing
Traditional surfacing, the classic method used in many older labs, creates lenses with two curves on the back, a sphere and a cylinder. Suitable for:
- Single-vision lenses
- Front-side progressives
- Bifocals
This process uses toric polishers with hard tools (metal, foam, or ceramic), along with varying grits of abrasive material, to refine the lenses from frosted to clear.
Digital Surfacing
Digital surfacing doesn't just cut two curves, it uses a surface topography map of the lens to cut highly detailed prescriptions, including:
- Digital progressives
- Digital bifocals
- Custom lens designs
Because digital generators are so precise, lenses often come out almost clear. Polishing requires only soft tools, making the process gentler and more accurate.
Protective Coatings
After polishing, the back surface of the lens is softer and more vulnerable. To ensure durability, every lens goes through a hard-coating process where a clear lacquer is applied for long-lasting protection.
