attenuation length

Attenuation length is the distance a light or other type of wave can travel through a material before its intensity decreases to about 37% (or 1/e) of its original strength. It measures how quickly the wave weakens as it moves through the material due to absorption or scattering. For example, in a clear liquid, the attenuation length tells us how deep light can travel before it becomes too faint to detect. A longer attenuation length indicates a clearer or less absorbing material, allowing waves to penetrate further.