Select machine vision lighting in this order: geometry, light pattern, wavelength, then filters. Keep the setup only when the feature stays separable on the samples you will run, including the oily, rotated, or slightly different ones. A clean sample that looks good once is not the decision.
Open the matching series, then send the part or the images.
Move the light, the part, or the camera until the feature separates from the background. On-axis light returns from a flat mirror-like face. Light from a low angle misses that face and can catch a scratch. Light from many directions, as in a dome, reduces a hotspot on a curve. If the feature is still mixed with the background, do not jump to a catalog adjective. Change the angle first.
A ring, a bar, a dome, a backlight, and a line light are different patterns, not different slogans. A ring surrounds the lens. A bar comes from one side and can be paired. A backlight makes a silhouette and does not inspect a surface scratch. A line light matches a moving web and a line-scan camera. Pick the pattern that matches the geometry you already found.
Change wavelength after geometry. A coating, oil film, plastic, or printed mark can reflect one colour and absorb another. The camera sensor also responds differently across the spectrum. Record the colour you tried and the one you rejected. Do not treat a wavelength as a fix for a light that is still in the wrong place.
A polarizer on the light and an analyzer on the lens can block a mirror reflection that geometry did not remove. A colour filter can block ambient factory light when the lamp is narrow-band. Filters also remove light, so exposure, gain, or a strobe may have to change. If the image only works with a filter angle nobody can repeat, the setup is not finished.
The feature stays separable when the part is rotated, when the finish varies, and when the ambient light is the light you will have on the machine. Write down the geometry, the model family, the wavelength, the filter, and the condition that made the feature disappear. That missing condition is part of the answer. It is also the input for a quotation or a sample test.
Change the position of the light relative to the camera and the part. Wavelength and filters come after the geometry has been tried. A new wavelength does not repair a light that is aimed at the wrong surface.
The feature you need can be separated from the background on the samples you will actually run, including rotated, oily, or slightly different parts. A result on one clean sample is a candidate, not the decision.
After the geometry is chosen. Coaxial, dome, and low-angle candidates are compared on the geometry page. Ring and bar candidates are compared on the ring-versus-bar page. The model page then carries the drawings and the listed options.
