UV LED Illumination for Fluorescent Inspection
- 365 nm and 395 nm excite different fluorophores.
- Leak detection finds tiny tracer leaks brightly.
- Security markers verified at production speed.
- Adhesive and sealant beads checked for continuity.
- Covered by RODER DL6, DC6, DL5 and FD2 UV illuminators.
Ultraviolet LED illumination opens applications that visible light cannot reach. Many materials, inks, coatings and biological substances fluoresce under UV. They absorb UV photons and re-emit visible light. Therefore, a standard camera captures this emission easily. As a result, invisible features become visible with very high contrast against a dark background.
UV Wavelengths in Industrial Vision
Industrial UV illuminators work at two main bands. These are 365 nm and 395 nm. The choice between them affects performance significantly. Therefore, it should match the fluorophore in use.
365 nm UV Illumination
Light at 365 nm sits firmly in the UV-A band. Therefore, it excites a wide range of fluorophores efficiently. However, it has a drawback. The LED efficiency at 365 nm is lower than at longer UV wavelengths. Consequently, more LEDs or higher current are needed for the same irradiance. As a result, thermal management becomes more critical here.
395 nm UV Illumination
Light at 395 nm borders the visible spectrum. Therefore, the eye sees it as a faint violet glow. The camera also detects it partially. Its advantage is higher LED efficiency and irradiance for the same power. Moreover, many tracers and security inks respond well to it.
This partial visibility has a consequence. Specifically, a short-pass or band-pass filter is needed on the lens. The filter blocks the excitation and passes only the fluorescence. Without it, the 395 nm background overwhelms the signal. Therefore, RODER Vision offers both 365 nm and 395 nm to match the fluorophore.
Fluorescent Leak Detection
Leak detection with fluorescent tracers is a high-value UV task. A small amount of UV-fluorescent dye is added to the fluid or gas. Then the exterior of the system is imaged under UV. The leaked tracer fluoresces brightly. Therefore, even very small leak points stand out against the dark background.
Hydraulic and Pneumatic Systems
Hydraulic systems use tracer dyes to find tiny leaks. These appear on hoses, connectors, seals and heat exchangers. The dye is added at 0.1% to 0.5% concentration. After running under pressure, the exterior is imaged under UV. Therefore, even a single drop fluoresces and is detected at once.
Machine vision replaces manual UV lamp inspection at volume. An automated station images the component at defined positions. The algorithm detects fluorescent spots above a size and intensity threshold. Therefore, it classifies each spot and triggers the reject for confirmed leaks.
Refrigeration and Air Conditioning
These systems require 100% leak testing before shipment. UV tracer dyes are compatible with most refrigerants and oils. The system is charged with traced refrigerant and pressurised. Therefore, UV vision then checks brazed joints, valve connections and pipe penetrations.
Security Marker and Authentication Verification
Security markers are invisible under white light but fluoresce under UV. They are widely used for authentication, document security and brand protection. Therefore, UV vision can verify their presence, position and content. Moreover, it does so at full production speed.
Pharmaceutical Label Authentication
Pharmaceutical labels often carry UV security features. These include UV-reactive inks, fluorescent fibres and UV-visible codes. Under UV, the system confirms all features are present and correctly placed. Therefore, the check integrates into the label station at line speed.
Document and Banknote Verification
High-security documents use complex UV-fluorescent patterns. These are hard to reproduce without the original ink formulas. Therefore, UV vision verifies the presence and pattern of these features. As a result, it rejects counterfeit or tampered documents in automated systems.
Adhesive, Sealant and Coating Inspection
Many adhesives and coatings contain UV-fluorescent additives. Therefore, their presence and coverage can be verified by UV vision. This happens after application and before assembly. As a result, defects are caught before they become costly.
Adhesive Bead Presence and Continuity
Structural adhesive must be continuous and correctly placed. It is applied to body panels, door seals and bonded assemblies. Under UV, the complete bead is imaged clearly. Therefore, the algorithm measures bead width and finds gaps or skips. It also confirms the bead sits within the position tolerance.
Gasket and Seal Compound Verification
Sealing compounds can also carry a UV additive. Therefore, UV vision confirms the compound on critical sealing faces. Missing or misplaced compound is detected before the joint is made. As a result, it prevents costly disassembly and rework.
UV Illuminator Design and Integration
UV systems need careful design for reliable, stable and safe operation. Three points deserve special attention. These are thermal management, camera filters and operator safety.
Camera Filter Requirements
Fluorescence imaging needs a filter on the lens. A long-pass or band-pass filter blocks the UV excitation. Therefore, it passes only the visible fluorescence emission. Without it, reflected UV overwhelms the weaker signal. For 365 nm, a cut-on at 400 to 420 nm is used. For 395 nm, a cut-on at 420 to 450 nm is needed. RODER Vision optical filter accessories complete the system.
Operator Safety
UV at 365 nm and 395 nm can harm the eyes and skin with sustained exposure. Therefore, UV illuminators are usually installed inside enclosed cells. This eliminates operator exposure during operation. When guards are open for setup, UV-protective eyewear is required. RODER Vision UV illuminators comply with CE marking for electrical and optical safety.
RODER Vision Illuminator Families for UV Applications
The families below support UV leak detection, security and adhesive inspection. Each one is available with 365 nm or 395 nm LEDs. Therefore, the right choice follows the geometry and the fluorophore.
DL6 Series — High-Density Matrix Illuminators
High-density matrix with MCCD© driver and HTTM© thermal control. Therefore, it suits area UV inspection of adhesive beads and security features over a wide field.
DC6 Series — High-Density Ring Illuminators
High-density ring light with even illumination around the lens. Therefore, it suits UV leak detection and label authentication on components. Available in 365 nm and 395 nm.
DL5 Series — High-Intensity Matrix Illuminators
High-intensity matrix that delivers strong UV irradiance. Therefore, it excites weak fluorophores and supports short exposures. Useful where 365 nm output must be maximised.
FD2 Series — Flat Dome Illuminators
Flat dome illuminator giving even, diffuse excitation. Therefore, it suits UV inspection of curved or reflective parts. It avoids hotspots on shiny adhesive and coating surfaces.
The right choice depends on the task and the geometry. For wide-area beads, the DL6 matrix leads. Component leak detection instead suits the DC6 ring. Weak fluorophores call for the DL5, which maximises irradiance. Curved parts favour the FD2 dome, which gives even excitation. In every case, RODER Vision provides matching optical filters and engineering support. Therefore, define the fluorophore, the wavelength and the geometry first, and then choose the matching light.
Frequently Asked Questions
365 nm excites a wide range of fluorophores but has lower LED efficiency, so it needs more careful thermal management. 395 nm is more efficient and brighter, but it is partially visible. Therefore, 395 nm requires a camera filter to block the excitation.
A small amount of UV-fluorescent dye is added to the fluid or gas, typically at 0.1 to 0.5 percent. The system runs under pressure, then the exterior is imaged under UV. The leaked tracer fluoresces brightly, so even a single drop is detected against the dark background.
The filter blocks the UV excitation and passes only the visible fluorescence. Without it, reflected UV overwhelms the weaker signal. For 365 nm, use a long-pass cut-on at 400 to 420 nm. For 395 nm, use 420 to 450 nm to block the stronger background.
UV at 365 and 395 nm can harm the eyes and skin with sustained exposure. Therefore, UV illuminators are usually installed inside enclosed cells, which eliminates exposure during operation. For open-guard setup, UV-protective eyewear is required, and RODER units are CE marked.
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Contacts & Information
Contact for general information : info@roder.it
Systems and Sensor Integration Partner : www.roder.it
RODER Artificial Vision Division : www.visiotronix.com
RODER Instruments Division : www.innovacheck.com
More information about VISIOTRONIX : about us
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Please note: Some images on this website have been intentionally generated using Artificial Intelligence (AI). This is due to the fact that, for many applications and projects, it is not possible to disclose photographs of the actual installation or system due to confidentiality agreements, contractual clauses, and Non-Disclosure Agreements (NDAs).