Glass Inspection and Quality Control via Industrial CT Scanning
Inspecting transparent objects like glass cups, medical vials, and cosmetic bottles presents a unique challenge for traditional metrology. Because glass has a different refractive index than air, light bends and distorts as it passes through the material. This makes optical measuring machines struggle or fail entirely to capture accurate data.
The Challenge of Transparency
On an optical system, a glass object is nearly “invisible” or creates “ghost images” due to diffraction. To bypass this, technicians often resort to “tricks,” such as filling containers with specialized liquids (like glycerine) that match the refractive index of the glass. However, this process is:
Messy and time-consuming: Requires filling, cleaning, and drying.
Impractical: Difficult to implement in a fast-paced production environment.
Limited: Does not allow for the measurement of complex internal radii or wall thickness variations.
The CT Scanning Advantage
Industrial Computed Tomography (CT) does not rely on light. Instead, it uses X-rays to penetrate the material, making it the perfect solution for the Medical, Cosmetic, and Food & Beverage sectors. Whether it is a glass cup, a pharmaceutical vial, or a perfume bottle, CT scanning allows for:
Precisive Wall Thickness: Map the entire thickness of the glass to ensure structural integrity.
Internal Geometry: Inspect internal radii and diameters that are unreachable by contact probes.
Non-Destructive Testing: No need to break or fill the object with liquids.
Total Visibility: Inspecting what is inside a sealed vial or bottle without opening it.
| Feature | Optical CMM (Vision) | Contact CMM (Touch Probe) | Computed Tomography (CT) |
| Transparency Handling | Poor: Refraction and diffraction cause high errors. | Good: Physical contact ignores transparency. | Excellent: X-rays are unaffected by optical refraction. |
| Internal Geometries | Very Difficult: Blocked by reflections. | Limited: Restricted by probe size/reach. | Total: Full 3D capture of internal/external walls. |
| Preparation Time | High: May require liquids (glycerine) or sprays. | Medium: Requires complex fixturing. | Low: Minimal setup; no “tricks” required. |
| Measurement Speed | Fast (if it works), but unreliable. | Slow (point-by-point). | Very Fast: Thousands of measurements in one scan. |
| Wall Thickness Map | Not possible. | Limited to specific points. | Complete: Full color-coded thickness map. |
