Dark Field Lighting

Dark Field Lighting (low-angle illumination) is used in machine vision when surface defects or contours are not sufficiently visible with frontal lighting. By directing light at a shallow angle across the object, the base surface reflects little to no light into the camera, while scratches, edges, and height variations scatter light toward the sensor. In practice, this means that both micro-defects and contour transitions appear with high contrast.

The effectiveness strongly depends on the geometry between light source, object, and camera; small changes in angle or working distance can completely alter the contrast. For contour inspection, dark field is often used to enhance edges, especially on shiny or reflective materials where backlight is not feasible. On diffuse surfaces, the effect is more limited due to uncontrolled light scattering.

In combination with a suitable camera and lens—providing sufficient resolution and a controlled viewing angle—dark field lighting enables reliable detection of very small deviations. Our range includes industrial LED dark field lighting in various configurations, where selection is directly linked to illumination angle, working distance, and the size of the defects or contours to be detected.