FFV (Free Form Verifier) is a special system for checking spectacle lenses. It enables fast and precise quality checks.
This applies to free-form lenses, progressive (PAL) lenses, toric lenses, and other lens types.
The system creates maps for spherical power, cylinder, addition, and difference.
These maps compare the made lens to its theoretical design.
The need for this system comes from the rise in customized free-form lenses over the past ten years.
These lenses allow full personalization to a customer’s prescription. However, they also require strict quality control.
The Lens Holder: Why It Matters?
The Lens Holder is a critical component of the FFV system, because it:
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Aligns the lens at the right angle: It matches the lens’s optical axis to the sensor’s axis. This ensures that every measurement is taken at the exact intended point.
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Preserves lens integrity: It stops direct contact between the lens and sensitive parts (Sensor Head, laser beams). This ensures that each inspection is not affected by fingerprints or surface defects.
The holder can hold many types of lenses.
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It can securely hold round lenses.
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It can also hold rectangular lenses.
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It works with edged lenses, whether they have beveled rims or not.
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Additionally, it can hold progressive and free-form lenses.
- Enables automatic calibration: The system detects the lens’s contours (Contour Detection) and performs an initial alignment without requiring complex manual intervention. Lens Installation Procedure Before each measurement, clean the lens. Use a lint-free flannel cloth and isopropyl alcohol. This will remove fingerprints and moisture.
- Adjusting for bevels or edged rims: If the lens has a bezel or edge, make sure the holder’s padded corners hold those edges gently. Do not apply pressure at all.
- Centering: Position the lens so that its optical center aligns exactly with the measurement datum defined in the software.
- Software setup: In the FFV user interface, choose the lens type (Free-Form, Toric, PAL, Spheric). Then, set the Go/No-Go tolerance criteria before you start the scan.
Once these steps are done, FFV can quickly measure without contact. It will mark each area right away, making sure each lens meets its design specifications.
