Circular Pattern in Image When Using a Camera With a Laser#
Issue#
In some applications involving lasers, especially laser beam profiling, you may see an interference pattern on the image, resembling a "bull's eye".
Reason#
This effect is commonly known as "Newton's Rings" and is caused by the laser light interacting with the image sensor's cover glass.
The effect varies depending on many variables, including the curvature of the cover glass, wavelength of light, incident angle, etc.
More details can be found here (Wikipedia).
Solution#
The only truly effective solution is to remove the image sensor's cover glass (e.g., Wilco Imaging in the US). However, this is a very labor-intensive process with a very high risk of damage to the sensor's die. Even a small particle of dust on an open die will damage many pixels.
For some cameras, Basler may be able to supply "glassless" cameras. However, due to the complexity of the handling process, a special contract with Basler is required. For most applications, or for applications using other models, Basler maintains a list of reputable third parties who can provide aftermarket cover glass removal.
Contact Basler sales or support to discuss your application and find an appropriate solution.