Ultraviolet (UV) Lighting for Machine Vision Applications
Some defects don't just have low contrast — they are genuinely invisible under any normal lighting. UV excitation is the only optical technique that can make them appear at all.
The Physical Problem
Certain features share the exact same color and reflectance as their surroundings under visible or infrared light: a hairline crack in clear plastic, a residue of adhesive, a trace of contaminating oil, or a security marking designed to be undetectable under normal light. No amount of repositioning, filtering or intensity adjustment under white, colored or IR illumination will ever separate these features from their background — the light reflected back to the camera from the defect and from the surrounding material is simply identical.
The Optical Solution
Certain materials fluoresce: they absorb high-energy ultraviolet photons and re-emit part of that absorbed energy as visible light at a longer wavelength — a real, well-documented photophysical effect known as the Stokes shift. Machine vision UV sources typically operate in the 365-405nm UV-A band. Illuminate the target with UV, and only the fluorescing material — the adhesive trace, the contaminant, the invisible ink — glows back in visible light, standing out sharply against a background that reflects almost none of it. Pairing the UV source with an optical filter that blocks the reflected UV excitation itself further isolates the fluorescent signal from any residual glare.
Wiring & Integration Recommendations
UV modules wire onto the same standard M12 pinout as our other lights. For maximum fluorescence contrast, work inside a darkened enclosure where possible — ambient visible light adds nothing to the fluorescent signal you're actually trying to capture, and only dilutes it.
Not Sure About the Optical Result?
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Describe your inspection challenge and one of our engineers will recommend the right optical approach.
Recommended Lighting Formats
Integration Tools
Application Notes & Optical Challenge Resolution
Three engineering application notes showing how the right optical principle — not a different camera or software — resolves the inspection challenge.
Industrial Context
Food & Beverage / PackagingOptical Problem
Saturating glare on glossy plastic film during seal inspection.
Solution & Geometry
630nm Diffuse Dome Lighting (omnidirectional light).
Physical Result
Elimination of the specular hot spot and light homogeneity above 90%.
Industrial Context
Pharmaceutical / VialsOptical Problem
Liquid fill-level inspection through an opaque amber glass vial.
Solution & Geometry
850nm Infrared Backlight, transmitted through the tinted glass.
Physical Result
Optimal transmittance through the liquid, clean contrast on the meniscus.
Industrial Context
Metalworking / AutomotiveOptical Problem
Reading a laser-marked Data Matrix (DPM) code on a machined metal surface.
Solution & Geometry
Darkfield Grazing Light + Crossed Polarization.
Physical Result
Cancellation of directional glare, clean separation of the code's micro-relief.
Application notes based on real physical and optical principles — exact outcomes depend on your configuration and are validated during a lab sample test.