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Machine Vision

Colored Light Selection Guide

There are many factors to consider when designing a lighting system for your smart camera.

Choosing the appropriate color (wavelength) of light is one of these factors.  It is also critical to consider ancillary factors such as lighting geometry, pattern, structure, and other elements that may influence the effectiveness of colored lighting for a specific application.

An Overview of Colored Lighting Options for Smart Cameras

Color White Infrared (IR) Red Green Blue Ultraviolet (UV)
Wavelength WHI 850nm - 1050nm 625nm-660nm 530nm 470nm 365nm - 395nm
Benefits Includes every wavelength of the spectrum IR light is invisible, so it is suitable in situations where visible wavelengths disturb workers Typically the least expensive; CCD sensitivity; is usually high High scattering rate 365nm light can cause materials to flouresce
Drawbacks Difficult to use bandpass filter to avoid interference from ambient light Double check camera sensitivity, some CCDs are not sensitive in IR range
IR light requires special polarization filters, be sure to use IR lens
High scattering rate could create noise on an object with many defects Be aware of safety precautions in environments where humans are present
Typical Applications Color camera applications For applications requiring that light penetrate through material like plastic such as plastic; where and object needs to be made to be seen through Any For inspecting green colored objects such as PCBs or wafers For applications requiring higher resolution of minor defects For inspecting glue, adhesives, paint, UV ink

How to use color reflection/absorption to obtain contrast

Does the part have color?
  • If the wavelength used is the same color as the object, the light will be reflected bright in the binary image.
  • If the wavelength used is opposite the color of the object, the light will be absorbed and present as dark in the binary image.



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