Lambertian emitter

LED is selected as standard because its luminous intensity distribution curve(LIDC)is close to that of Lambert light source.

鉴于LED标准管具有量值传递方便进而统一量值的优点,指出作为标准管不仅要保证赋值的准确性和其量值保持长期稳定性,选择LED标准管要求其配光曲线要好,即接近朗伯发光体。