Application of Machine Vision Lighting in Industrial Inspection

Machine vision lighting systems are critical to the proper function of the vision system. The human eye can quickly adjust and see objects under various complex conditions. Machine vision systems applied to industrial inspections are technologically advanced, but they still cannot recognize objects the way the human eye can. Therefore, there is a need to provide proper lighting for machine vision systems to improve system performance.

Ⅰ. Matters needing attention in machine vision lighting

Machine vision lighting must be consistent and stable. If the light changes, industrial inspection systems may misinterpret this change as a change in the product itself. Machine vision lighting should magnify elements of the part to be inspected and also reduce elements that do not need to be inspected.

Good machine vision lighting can make industrial inspections faster and improve accuracy. Poor lighting often leads to errors and malfunctions. Most of the time, existing lighting is not sufficient for machine vision. If the head lighting dims or burns out, the machine vision system may report an error on the production line. Therefore, it is important to install a dedicated machine vision lighting system.

Ⅱ. Types of machine vision lighting

Because lighting is critical to machine vision and industrial inspection, there are several options to ensure a vision system has the best lighting for its application. Below are some of the telecentric lighting types available.

1. Backlight

Backlighting provides uniform illumination from behind the object being inspected, which highlights the outline of the object, backlighting is suitable for industrial inspection of holes, object outlines and scratches on transparent parts. Backlighting is not suitable for inspecting object surface details.

2. Dark field lighting

Dark field illumination is suitable for detecting the surface features of the object surface. This method provides light at a shallow angle to the object to be inspected, highlighting the scratches, edges and notches on the object surface, while the rest of the object surface is darker. Any angle that can be tilted can be used. directional light.

3. Dome lighting

If even light is required to eliminate glare, dome lighting provides light from all angles without glare, even on mirrored objects. Dome lighting works best with shiny surfaces. The dome light must be installed close to the object being inspected.

4. Low angle dark field lighting

This form of lighting shines on the subject at an angle of 10-15 degrees. Surface features such as scuffs and fingerprints appear shiny on the mirror surface while the rest of the surface remains dark. Height differences are also highlighted.

5. Ring lighting

Ring lighting illuminates the surface of an object with a ring of bright, intense light. It removes shadows and provides good contrast. But this can cause glare on reflective parts. Ring lighting is widely used in various industrial inspections.