The amount of light emitted by one candle that falls on one square foot of surface one foot away is called a lumen ( lm ) 光的量是由一支蜡?由一英?的距离照在一平方英?的地方做为计量单位:流明。
lumen (lm) meaning:[Architecture] The SI unit of luminous flux equal to the luminous flux received on a unit surface, all points of which are equidistant from a point source having a uniform intensity of 1 candela.