Lens secondary processing transforms semi-finished lenses (SFLs) into final, wearable eyeglasses—combining precision craftsmanship with modern technology to meet unique prescriptions, frame requirements, and lifestyle needs. Below, we break down the key steps: grinding, surface treatments, and finishing processes that deliver high-quality, custom lenses.
Grinding is the core process that molds the concave (inner) side of SFLs into functional, prescription-matched curves. Traditional methods handled simple spherical/cylindrical shapes, but free-form surface technology now enables custom curves for progressive, aspheric, and other complex prescriptions—revolutionizing how we address astigmatism, presbyopia, and high-index needs.
The process balances accuracy with efficiency, whether using traditional tools or CNC (computer numerical control) machines:
- Lens Retrieval: SFLs—single-vision (10–25 types) or progressive (over 200 convex-side designs)—are selected from inventory via order management systems, matching your prescription and frame.
- Design Marking: Reference lines (center point, astigmatic axis, prism base) are marked on the convex side, and a protective tape is applied to prevent scratches during processing.
- Mounting: The marked SFL is secured to a fixture with low-melting-point wax, ready for grinding.
- Cutting/Grinding: Diamond wheels shape spherical/cylindrical lenses; CNC turning creates free-form surfaces (inner progressive/aspheric) for better vision.
- Fine Grinding: A sandpaper-like pad smooths rough-grinded surfaces (removing ~10-micron irregularities) to avoid polishing delays or shape distortion.
- Polishing & Inspection: Alumina slurry polishes lenses to a mirror finish (free-form lenses skip fine grinding). Post-polishing, lenses are cleaned, demounted, and inspected for power, prism, thickness, and defects (scratches, gaps).
Specialized grinding solves specific user challenges:
- Thinner Edges: Trimmed diameters for plus/mixed lenses reduce bulk and weight.
- Ultra-Thin Lenses: Minimized edge thickness for a sleeker, more comfortable fit.
- Precise Prescriptions: Half-diopter (0.125D) increments for exact vision correction.
- Decentered Lenses: Shifted optical centers for larger frames.
- Prism Lenses: Redirect light to treat strabismus or alignment issues.
Surface treatments add value by solving common pain points—from scratches to glare. Here’s how each coating benefits you:
Dyeing adjusts hue (tone), lightness (brightness), and saturation (vividness) to match your style. Colors are tested under sunlight, fluorescent, and incandescent light to ensure consistency. Methods include:
- Dip Dyeing: Plastic lenses soak in 85–95°C disperse dye (adjusted for depth).
- Transfer Dyeing: Dye printed on paper is heat-applied to non-dyeable materials.
- Anti-Scratch: A mix of inorganic oxides and organic silanes prevents daily wear (critical for plastic lenses). Applied via dip or spin coating, then cured with heat or UV light.
- Anti-Reflective (AR): Reduces surface reflection from ~10% to 1–1.5%, eliminating glare from screens, headlights, and bright light. Inorganic AR (5–7 oxide layers via vacuum deposition) offers 98.5–99% transmittance—ideal for high-index lenses.
- Waterproof/Anti-Fouling: Silicone/fluoride layers repel water and fingerprints for easy cleaning.
- Anti-Fog: Hydrophilic surfactants spread moisture into a thin film (no fogging from masks or cold weather).
- UV Protection: Blocks UV rays below 400 nm to prevent lens degradation and eye damage.
- Blue Light Filter: Reduces eye strain from screens by filtering 400–450 nm blue-violet light.
The final steps ensure your lenses are wearable, identifiable, and frame-ready:
Manufacturers etch brand logos, progressive fitting markers, and spec codes (outside the vision zone) using:
- Mold Transfer: Pressed into lenses during casting.
- Laser/Diamond Etching: Applied pre- or post-coating for precision.
Progressive lenses include printed guides—horizontal lines, fitting points, and power markers—to ensure accurate alignment during frame fitting.
Shapes lenses to match your frame:
- Digital Edging: Uses CNC machines and frame measurement data (no physical frame needed) for a precise, gap-free fit.
- Traditional Edging: Uses templates traced from frames for classic styles.
From custom grinding to anti-glare coatings, lens secondary processing turns generic SFLs into personalized eyewear that meets your vision, style, and lifestyle needs. Every step—rooted in precision and innovation—ensures you get lenses that are as unique as you are.
All images referenced in the original document are omitted from this text.
