Luminance describes how bright the human eye perceives luminous or illuminated surfaces. The unit of measurement is candela per square meter (cd/m²).
- If we look into the midday sun with its luminance of 1,600 x 106 cd/m², we risk serious eye damage, while at 2,500 cd/m², the sunlight reflected from the moon is gentle on the eyes. However, staring into an opaque 60-watt light bulb (~ 120,000 cd/m²) is unpleasant.
- Depending on the manufacturer, the luminescence of a laser high beam is between 600 and 1,000 cd/mm²—n other words, 600 million to 1 billion cd/m². The high dazzle effect for other road users is specifically prevented with the help of camera-based control systems.