The wavelengths of these rays range from 360 to 830nm, a very small part of the electromagnetic spectrum. LED luminous flux, in unit of Lumen (LM). All radiant energy emitted by a light source and perceived by human eyes is called luminous flux. Luminous intensity (luminous intensity,I). The flux of a light source at a solid Angle in a certain direction. Generally, LED light sources emit light flux in different directions at different intensives. The intensity of visible light emitted ina particular direction is called Illuminance (E, Lux, Lx). Illuminance is the ratio of the luminous flux to the surface being illuminated. Luminance (L) refers to the intensity of light reflected from an object seen by the eye in one direction. Luminance (L) refers to the efficiency with which electrical energy is converted into light energy. Luminance (L), unit, candela per square meter (CD/square meter). Common-Cathode CC 3101AB 7-Segment digit 3101AB LED Common-Anode CA 3101BB Display 3101BB 0.30 inch Common-Cathode CC 3011AB 7-Segment digit 3011AB LED Common-Anode CA 3011BB Display 3011BB 0.30 inch