Selecting UV Wavelengths for Machine Vision Applications

September 9, 2025

Ultraviolet (UV) radiation is becoming increasingly common in machine vision applications, enabling detection capabilities beyond the range of human vision. With advancements in technology, UV vision systems are gaining traction, leading to increased demand for UV illumination and expanding the scope of machine vision applications.

What is UV Lighting?

UV is a type of electromagnetic radiation with wavelengths that are shorter than visible light but longer than x-rays. It is invisible to the human eye and UV wavelengths range from 100 to 400 nanometres (nm). It is naturally emitted from the sun but can also be produced by artificial sources in industrial applications.

UV for Machine Vision

In the world of machine vision, UV illumination unlocks an entirely new sector of inspection power. Unlike standard LED lighting, UV light reveals what the naked eye can’t see. By creating fluorescence excitation in specialised materials, UV light highlights hidden features and illuminates microscopic contaminants with stunning clarity. This has elevated the industry, opening doors to advanced applications and expanding machine vision into wider markets.

UV Wavelength Bands

UV is divided into these wavelength ranges:

UV-A (315 – 400 nm) – Most commonly used in machine vision. Used for fluorescence inspection, surface inspection, detecting invisible markings, adhesives, and inks.
UV-B (280 – 315 nm) – Has deeper penetration and higher energy. This is less common in machine vision due to safety concerns, but useful for specific inspection tasks for specialised material analysis or defect detection.
UV-C (100 – 280 nm) – A rarely used option due to hazards and low sensor compatibility. For machine vision, UV-C is mainly used in specialised applications like germ detection or biofilm analysis.

UV-A spectrum is the most widely used UV band in machine vision because it offers both high performance and safety. Its wavelengths (315–400 nm) trigger fluorescence in many materials, showing hidden features and contaminants, while remaining safe for most equipment and easy integration.

Machine vision systems using UV-A light are valuable in a range of industries. Applications include inspecting pharmaceutical packaging for tampering, verifying security features on documents and currency, and detecting contaminants on surfaces.

UV-A Wavelengths (315-400 nm)

365 nm
This wavelength is the industry standard for fluorescence imaging. It reacts with a wide range of substances like inks, glues, and dyes, making it ideal for applications that need high contrast. It’s particularly useful for detecting surface defects, invisible markings, and contaminants that can’t be seen under visible light.

Commonly used in applications:

Pharmaceutical Packaging Inspection
Adhesive verification
Anti-counterfeit inspection
Forensic-quality defect detection
Cleanliness verification

375–385 nm
This range produces strong fluorescence in many materials. With broader LED availability and greater efficiency, this option is a practical choice for general-purpose UV inspections with enhanced durability and performance.

Commonly used in applications:

Food and beverage inspection
Automotive assembly
Cosmetic packaging quality control
Textile or fabric inspection

395 nm
Positioned at the edge of the visible violet spectrum, 395 nm doesn’t create as much fluorescence, but it is excellent for inspecting materials that reflect or absorb UV strongly. It’s commonly used in applications that need more reflectivity than fluorescence, like in surface texture analysis or detecting marks on dark materials.

Commonly used in applications:

Surface inspection on dark materials
Label presence verification
Printed circuit board and component checking
Packaging seal inspection

Selecting the Correct UV Light Solution

Choosing between 365 nm, 375–385 nm, and 395 nm depends on your application needs. It’s essential to consider the materials you’re inspecting and the visual effect you require. Use 365 nm for strong fluorescence and high contrast, 375–385 nm for a balance of performance and durability, and 395 nm when reflectivity matters more than fluorescence. Matching the wavelength to your inspection goal ensures optimal imaging results and system efficiency.

As UV technology continues to advance, its role in machine vision is becoming more impactful than ever. By leveraging the unique capabilities of UV illumination, industries can achieve greater inspection accuracy, uncover hidden defects, and maintain higher quality standards across a wide range of applications. As machine vision systems evolve, UV lighting remains a powerful tool for pushing the boundaries of what’s visible—and what’s possible.