A quick look at color lighting and filters for vision sensors
Bob Tremblay, 08-30-2011
Effective color lighting and filter technology turns your ordinary vision sensor into a Super vision sensor.
With the right lighting and filters, your vision sensors create stronger image contrast resulting in more consistent and accurate optical inspection results.
Visible colored illumination such as red and green allow you to optimize the contrast of features you are looking to inspect . If you were inspecting for the presence of a safety seal with red print over a white cap using green light would make the print appear black while using red lighting would remove the red print from the image.
In some factories flashing lights are a safety concern as it can distract line operators performing tasks. This can be overcome by using Infrared lighting which is invisible to the human eye.
One of the largest problems one faces in successfully deploying a vision sensor will be dealing with changes in factory lighting conditions. Through the use of colored lighting and bandpass filtering one can completely eliminate these influences resulting in more consistent and accurate optical inspection results.
Using polarization filters lets you drastically reduce specular reflections “or glare” which can obscure features and cause inconsistent optical inspection results from your vision sensor.
From a cost and simplicity of integration perspective having a lighting and filter solution which is integrated into your vision sensor housing gives you the most affordable and tightly integrated solution.
At the end of the day the more consistent the image appears the more consistent your inspection results will be.