Surface inspection of UCAV camera lenses
On an indexing table the lens moves under a dark-field ring light. The clean surface stays dark, while scratches, digs and coating defects scatter the light and show up bright. Each defect is measured and graded by size class.
Defect count, scratch width, dig diameter and size class are written to the quality record for every lens, and the annotated image is shown on the operator display. For a lens beyond the class limit the stack light signals NG and the lens is flagged for removal.
- 01 Index
- 02 Dark field
- 03 Detect
- 04 Grade
- 05 Decide
The rotary table brings the next lens under the camera.
- Defect count
- —
- Scratch width
- —
- Scratch-dig
- —
Scenes are illustrative simulations; they are not customer references or performance guarantees.
Need
Scratches and digs are almost too small to see, while the polished, curved glass reflects light like a mirror. Under direct lighting the reflection swamps the defect; in dark field, stray ambient light and dust light up just like defects.
Solution approach
The ring light around the lens strikes the surface at a very low angle; light reflected by the clean surface misses the camera and the image stays dark. Only scratches, digs and coating defects scatter light into it. Each bright region is marked; a scratch is sized by comparing its transverse intensity profile with reference scratches, a dig by its diameter, and a size class is assigned.
Process steps
- 01
Index
The rotary table brings the next lens under the camera.
- 02
Dark field
The ring light illuminates at a low angle; only surface defects scatter light.
- 03
Detect
Each bright scratch, dig and coating blemish is marked.
- 04
Grade
Scratch width and dig diameter are measured and a size class is assigned.
- 05
Decide
The lens class is compared with the permitted limit.
Related applications
Let us assess your application together
We test your sample in our laboratory and report on resolution, optics and lighting selection.