retroreflektioarvoa

Retroreflektioarvo, or retroreflective value, is a measure of how effectively a material reflects light back toward its light source. It describes the property of retroreflection, which helps objects become visible to observers located near a light source, such as drivers at night. Materials with a higher retroreflektioarvo appear brighter when illuminated from the direction of the light source.

The retroreflektioarvo is typically measured with a retroreflectometer under standardized geometries. The value is usually reported as a retroreflection coefficient, R, in units such as cd/lux/m², with higher numbers indicating greater brightness. In practice, many applications also refer to RA or RL values, which reflect specific measurement geometries or conditions. Standards set the test setup, light source, observation angles, and how results are expressed to ensure comparability between products.

Several factors influence retroreflection. The microstructure of the material, such as glass bead bead-on-surface designs or cube-corner prisms, determines how light is redirected back toward the source. The angle of illumination and viewing, surface smoothness, dirt, moisture, wear, and aging all affect performance. Weathering and abrasion can reduce the retroreflective value over time, making cleaning and maintenance important for long-term visibility.

Common applications include high-visibility clothing, road signs, reflective safety markings on vehicles, and traffic control devices. Standards in international and national contexts govern measurement methods and minimum retroreflection requirements for different uses, ensuring predictable performance across conditions.