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.