Vision systems save manufacturers time and money by streamlining product assessments on the production line. This technology scans and processes digital images at high speeds using a combination of sensors, lenses, and processors. 

Vision systems lighting illuminates objects and enables the internal camera to identify faulty features like cracks and surface warping without hassle.  

Read on as our developers at Sciotex explain why proper lighting is vital to digital imaging. Additionally, these professionals recommend practical lighting techniques that may help during your next inspection. 

What Is Machine Vision Lighting?

In the past, engineers did not integrate lighting features into vision system hardware. Most companies inspected products for defects using fluorescent bulbs or simple room lighting. As you can expect, these solutions created considerable delays in the production process. 

Despite advancements in modern vision systems, optical lenses still depend on sufficient lighting to operate efficiently. Often, these machines must complete 3D scans of an object’s surface to identify defects. Blind spots and shadows can reduce a system’s ability to grade surfaces accurately. 

Dedicated machine vision lighting solves this problem with cutting-edge illumination features. Some vision inspection systems utilize built-in lighting, while others provide space for mounted fixtures. 

Vision systems lighting allows you to adjust the position of a light source according to your spatial limitations. With the proper techniques, machine vision lighting will: 

·       Enhance imaging quality

·       Reduce the presence of blur and glare

·       Eliminate ambient lighting in darker rooms

·       Improve the depth and contrast of the target object

·       Increase inspection output 

Types of Light

You can use different types of lighting to assist the camera in capturing high-quality images. Colors and wavelength play a crucial role in identifying the right lighting for a target object.  

Color

A target object’s surface color may prevent your camera from capturing textures and defects. Try using a different color to improve visibility.  Many lighting color combinations for vision systems imaging scenarios exist.

For example, yellow lights on a white or yellow object will create obstructive glare and reduce the contrast between the object and the background. Using a red or green color may provide more context to the image. 

Alternative Imaging

Ultraviolet and infrared lights can clarify features that may disappear under conventional lighting.  

For example, circuitry manufacturers can use ultraviolet light to identify soldering features in greater detail. Furthermore, they can use infrared to isolate these features from elements that may interfere with the inspection, like reflections. 

Vision System Lighting Techniques

Optimizing your vision systems lighting technique requires precise calibration. Angles, distance, and brightness impact the camera’s ability to capture certain features of your object.  

Let’s take a look at some of the most popular lighting techniques among technicians:

Ring Technique

Ring lighting is one of the most effective ways to conduct inspections on small parts and stationary objects. These light fixtures attach to the camera around the lens and illuminate the target object from above. 

Because the light surrounds the object, you can enjoy a complete picture of the material without room light interference.  

Still, a ring light may not be appropriate if you need to assess features like fading text on a product label. A bright-light field can wash out small details and make them hard for the camera to pick up. 

Backlighting Solutions

Backlighting solutions are excellent for producing high-contrast images.  

A light source shines from below your target to the camera lens. This method purposefully creates a shadow around the object to help you view measurements and shapes accurately. 

Backlighting exposes holes and cracks in the surface of thin objects. Try using RGB color to get the most out of this solution. These colors emphasize edges and hair-thin damages.
 

Single/Multi-Directional Lighting

You can control shadows with single and multi-directional vision system lighting techniques.  

A dark-field light reflects excess glare away from the camera lens and allow you to view convex surface features. This option is suitable for inspecting highly reflective objects. Conversely, directional bright-field lights can illuminate surfaces and reduce contrast around the object. This solution works best for concave features and holes. 

You can also create a multi-directional solution using several different light sources. Or control lighting through polarization. Using multiple lights reduces blind spots. Moreover, this strategy enables the camera to complete a 3D scan without you needing to reposition the mounts.  

Dome Lights

Dome lights achieve the most uniform multi-directional lighting solution. These fixtures create an entire bright-light field around the object. However, the dome light must be close enough to the target object to illuminate every surface evenly. 

Large objects may not always fit under dome lighting and will require alternative solutions, such as bar lights.
 

Bar Lights

Bar lights are the best solution when inspecting large or dusty surfaces. These tools ignore dirty surface particles and enable the camera to take high-contrast images. 

Automobile manufacturers use these lighting techniques to assess large parts. 

Target Axis 

This solution utilizes a light splitter that illuminates the target object from above. Overhead lighting minimizes shadow interference and diffuses light around the object’s surface. Moreover, this bright-field method prevents blurriness in the camera that may occur from reflective or glossy objects. Like dome lighting, this solution is most effective at a close distance. 

Choosing the Right Lighting Solution

It may be challenging to determine which technique is the best solution for your needs. With vision systems lighting, there is no one-size-fits-all option. Fortunately, you can consider several factors that help you decide. 

Goals

Choosing the right lighting solution depends on your company’s production standards. Ask yourself what type of objects go through your inspection process.  

·       How much detail do you require from your images? 

·       Are you looking for significant faults, like surface fractures? 

·       Do you need to assess microscopic damage, like weaknesses in adhesive?

·       Will you need to accurately measure defects for reporting purposes? 

The answers to these questions will determine which lighting technique is best for you. 

Assessing the Object

Assessing the objects you work with may help you discover the right solution. If you work with large or thick objects, a ring lighting solution won’t do you any good. Conversely, bright-light fields may not be the best choice for tiny or reflective materials. 

Consider that a glass producer may need a lighting solution that allows them to view weak points on the surface of their products. Backlighting solutions may enable the camera to view microscopic cracks and other features. 

Alternatively, engineers in the automotive industry may require directional lighting to inspect the quality of metal sheets and bolts. 

Distance

The distance of your lighting sources to an object can make or break image quality. 

Some limitations may restrict you from positioning your light source in the proper place. Fortunately, many vision inspection system producers can offer personalized light mounts that fit wherever you need them.  

Speed

Using the wrong lighting technique on a fast-moving production line may create image blur. 

Several vision inspection systems on the market, like ConveyorVIEW, provide high-resolution imaging for objects in motion. Still, calibrating the system with the right lighting solution will significantly enhance your results. 

Testing

Testing different lighting techniques is the only way to know which solutions work for you. Each lighting technique performs well in controlled spaces. Still, they may not yield the results you expect.  

The best way to start is by performing an inspection without vision systems lighting. This method lets you view what your camera catches naturally and which features it struggles to detect. Attempt to resolve these issues by testing both bright and dark-light fields. 

Even if you find a lighting solution that works, experiment with different colors to improve image clarity. Using a color camera will allow you to explore which hue displays the best detail. Additionally, try placing the light source in different spaces around the room to track lens glare.  

Testing your light solution may take some creativity, but achieving a clear image makes it well worth the effort. 

Investing in a Customizable Solution

Partnering with a professional vision inspection system distributor is an excellent way to ensure that you get the most out of your lighting solution.  

Many companies develop dedicated lighting systems to match their clients’ specific applications.  

Some manufacturers require larger machines that will fit the measurements of their products. Others require more than one lighting system if they produce multiple items in a single location.  

Professionals will save you time and money by providing advice on how to accomplish the best image quality for your inspection. 

Conclusion

If you aren’t getting the desired results, you should speak to our tech experts. 

At Sciotex, we provide clients with some of the most reliable vision inspection systems and appliances on the market. We recruit a dedicated team of developers and engineers with years of experience. 

Our company uses cutting edge-technology to help customers achieve the highest return on their investments. We commit to providing ongoing technical and operational collaboration when you need it. Continue exploring our website or ask us questions about these additional services. 

Contact our Sciotex team in Newtown Square, PA, to learn more about vision systems lighting. Call us at (610) 459-9646 today.