Ensuring perfection on production lines, detecting invisible flaws in a fraction of a second, or fully automating quality control processes... Today, all of this is possible thanks to industrial machine vision systems. However, the heart of these systems isn't just state-of-the-art cameras or complex AI algorithms. Often staying in the background but ultimately deciding the system's fate, the true hero is lighting.
No matter how high-end the camera is, without the right light, issues like reflections, dark spots, shadows, and low contrast can render all the data unusable. In short, "what the camera sees" in industrial systems is strictly tied to "how the lighting shows" the object to it.
In this newly launched blog series, we are opening the doors to the world of industrial machine vision and examining that delicate balance between camera and lighting. In this first installment of our series, we take a closer look at LED lighting technologies—indispensable to modern systems—and the lighting scenarios (ring, bar, back, dome, etc.) that work wonders on different surfaces.
If you're ready, let's turn on the lights!
1. Why LED Lighting? Thanks to their low energy consumption, long lifespan, and stable light output, LED lights have now become the gold standard in industrial vision systems.
Stable light output
Long lifespan
Low energy consumption
High controllability
These advantages make LEDs indispensable in modern machine vision applications. Providing lower heat emission and more stable light generation compared to traditional light sources is of great importance, especially in applications requiring micron-level precision measurement. Furthermore, their ability to turn on and off at the microsecond level allows them to operate in perfect synchronization with the camera shutter. This way, motion blur that might occur on fast-moving objects flowing down the production line is minimized.
Another fantastic feature of LED lighting is that it can be manufactured in various wavelengths. This allows for the selection of the appropriate light color to create contrast based on the optical properties and color of the inspected object, making surface defects much more prominent.
However, we must not forget that lighting performance depends not only on the type of light source but also on how the light is applied to the object. Let's take a look at the most commonly used LED lighting configurations together.
2. LED Lighting Configurations Based on Needs
Ring Light: One of the most popular configurations. It is based on the principle of placing the light source around the camera lens, allowing the light to hit the object's surface at a nearly perpendicular angle. Thanks to this structure, the surface is illuminated homogeneously, and annoying shadows are greatly reduced. It is particularly effective for capturing the general image of flat and small parts. However, since the light strikes at a right angle, it can "hide" some micro-surface flaws; thus, it may not be sufficient on its own for highly detailed scratch or dent analysis.
Bar Light: In this method, linear LED sources are positioned at specific angles to the object, usually from the sides. Because the light hits the surface at an oblique angle, topographical defects such as scratches, bumps, dents, and recesses create shadows, making them much more visible. It is an excellent solution for inspecting large surfaces and for use on moving production lines. The adjustable light angle depending on the project provides engineers with immense flexibility.
Backlight: A method where the light source is placed directly behind the object, while the camera looks from the front. In this technique, the object is perceived by the camera as a pitch-black silhouette. It provides tremendous accuracy, especially for defining the contours of a part, precision dimensional measurement, and hole/shape analysis. It is also highly effective in inspecting transparent or translucent materials. It highlights the physical form of the object rather than its surface details (color, texture).
Dome Light: What happens when you shine a light directly on a shiny metal or packaging surface? The camera sees nothing due to glare. Dome lighting solves exactly this problem. It is a system that allows light to reach the object in an indirect and diffused manner. The light reflects inside a hemispherical dome structure and distributes softly and homogeneously onto the surface from every angle. It is the best choice for preventing glare on metal, glass, plastic, or polished surfaces.
Spot Light: A targeted method used to intensely illuminate a specific area. By focusing the light on a narrow area, small details or defects located in a specific region of the part can be highlighted. Since it does not provide homogeneous illumination, it is preferred in applications where we say, "I just need to inspect this pin or barcode right here," rather than for general imaging (seeing the whole part). [IMAGE: image11.png]
In summary; In industrial machine vision systems, LED lights are not just simple "light bulbs"; they are critical optical components that determine the success of the system through their wavelength, angle, diffusion method, and synchronization. Selecting the appropriate lighting type and geometry is the fundamental building block that ensures system accuracy and allows the AI/software to make the correct decisions.
In the next part of our blog series, we will touch upon the types of industrial cameras that work seamlessly with these lighting setups and discuss the importance of lens selection. Stay tuned!
