Valonmäärä
Valonmäärä, often translated as "light quantity" or "amount of light," is a fundamental concept in photometry and illumination engineering. It refers to the total amount of visible light emitted by a source or received by a surface over a specific period. Unlike illuminance, which measures the intensity of light falling on a surface at a given moment, valonmäärä considers the duration.
The standard SI unit for valonmäärä is the lumen-second (lm·s). This unit is derived from the lumen
In practical applications, valonmäärä is important for understanding total light exposure. For example, when designing lighting