Imaging fluorescence measurement technology

Using the fluorescence of coatings or impurities for measurements

While oil, grease and polymers are often used as coatings, they can also contaminate components. Autofluorescence is a way of detecting whether a component is covered or contaminated with one of these substances: They glow when irradiated with light. Violet or ultraviolet light in particular can be used to detect organic materials with great sensitivity.

To employ fluorescence in measurement technology, the component’s surface must be illuminated using a strong light source, such as a laser or an LED. Optical filters will then separate the fluorescent light from the short-wave excitation light. The fluorescent light is then detected by cameras or even more sensitive detectors.

Fluorescence measurement technology on the production line

Fluorescence measurement technology is a powerful quality control method – whether for detecting impurities or checking the accuracy of coatings. Checking surfaces or coatings for organic contamination is becoming more and more important, in particular in the production of high-tech components. For example, surfaces need to be contamination-free for sensitive processes such as galvanizing or bonding. The same applies to vacuum or sterile applications. In turn, surface coatings are essential for processes such as deep drawing or mold parting components.

Fraunhofer IPM develops highly sensitive, very fast and robust fluorescence imaging systems for a range of very different applications, both for integration in production lines and for use in laboratories. Examples include 100 percent checks of oiled sheets in the production of vehicle body parts or devices for detecting even minute impurities on electronic housing components. The dedicated software solutions enable the presentation and processing of data at the rate of production. Mechanics, optics, electronics, software and interfaces are customized for both laboratory equipment and production line systems.

Laser scanner or camera system?

Our F-Scanner systems combine highly-sensitive, laser-excited fluorescence measurement with laser scanning to enable large-scale and fast imaging. A violet laser beam is moved over the component surface by a deflection unit., while fluorescence is being detected simultaneously. Based on the measurement data, the software generates a high-resolution image of contaminations or coatings on the component surface.

Smaller components of up to 100 cm² are inspected using the high-resolution F-Camera system for even greater detail. This system allows for the combination of fluorescence with other imaging techniques to detect particles or defects, producing highly conclusive image data.

Both systems are available in several versions – always tailor-made for a specific application – for use in laboratories, stationary inline use or even robotics applications. For the inspection of bulk mass-produced parts, Fraunhofer IPM offers fluorescence measurement in free fall, which scans all sides of a component simultaneously without complex handling. The method can be combined with a detailed geometry inspection.