Light filtering is a typical need in machine vision applications.
Together with LED illuminators, filters can improve image contrast by
blocking unwanted light and increase the accuracy and repeatability
of the vision system.
Ambient light is very frequently causing errors in imaging systems
due to unwanted reflections off the surface of the parts being
measured. In these cases, a band pass or long pass filter that
matches the emission wavelength of the illuminator is usually
integrated in front of the imaging lens: this way, only the light coming
from the illuminator is collected while the rest of the spectrum is cut
out.
Furthermore, many machine vision applications require
monochrome illumination in order to enhance or suppress
particular object features: under these conditions, only the features
with a certain color are imaged and inspected.
