Fluorescence Intensity Density
The brightness of excited indicator particles under UV-A radiation for reliable visual detection of the smallest surface cracks.
Physical-Chemical Mechanism of Action
Fluorescent intensity density refers to the brightness of indicator particles that, when excited under UV-A radiation, release their energy in the form of light. This process is called fluorescence.
Metallurgical Relevance & Risks in Welding
Fluorescent intensity density is important for visual detection of surface cracks and defects in the weld. A high intensity level indicates strong particle excitation and points to the smallest cracks that would not be visible to the naked eye. A low intensity level may indicate that the surface is clean or that the indicator particles could not be excited.
Workshop Practice & Instructions
To measure and interpret fluorescent intensity density, a special UV-A light is used. The intensity of the light should be set so that it is sufficient for the excited indicator particles but not so high that it damages the surface. A high intensity level (e.g. above 100 mW/cm²) indicates the smallest cracks and should lead to further inspection or repair.