Glossary · Machine vision
Bright-field illumination
Also known as: Bright-field lighting
German: Hellfeldbeleuchtung
In machine vision, bright-field illumination is a lighting arrangement in which light reflected directly from the object's surface reaches the camera, so flat, reflective areas appear bright and features that scatter light, such as scratches or engravings, appear dark.
- Machine vision
In one sentence
Bright-field illumination sends reflected light straight into the camera, so flat surfaces look bright and scattering features dark.
Example
Coaxial bright-field illumination makes the laser-etched code on a polished shaft appear dark on a bright background.
How it applies
- Engineering: Bright-field is achieved with coaxial lights, ring lights at a steep angle or dome lights, depending on the surface. It suits flat, reflective parts and printed or etched marks.
- Commissioning: Angle and distance of the light are critical; small changes in part tilt change the image strongly on shiny surfaces.
- Documentation: The documentation team should document the light type, angle and distance, ideally with a photo of the setup, so that maintenance can restore it after a replacement.
Bright-field vs. dark-field illumination
In bright-field, directly reflected light enters the camera. In Dark-field illumination, light arrives at a low angle and only scattered light enters the camera, so the contrast is reversed.