illuminance; intensity of illumination
Technical term for the amount of light falling on a surface, measured in lux. Used in lighting design, photography, and workplace safety standards.
An illuminance of 500 lux or more is recommended for offices.
Please measure the illuminance in this room.
照度 measures the amount of light falling on a surface (illuminance, in lux), while 輝度 measures the light emitted or reflected from a surface (luminance, in cd/m²), so learners often mix the two up.
Compound of 照 (illuminate) and 度 (degree, measure).