The relationship between led fluorescent light flux, light intensity, brightness and illuminance
Luminous flux is an indicator of the overall brightness of the light source. The unit is lm (lumens). It is often used to indicate the glare of LEDs for display. It is defined as a light source emitting 540×1012Hz (wavelength 555nm) frequency monochromatic light, the light emission intensity in the specified direction is 1/683W/sr, and the light intensity in this direction is defined as 1cd.
Brightness is an indicator of the intensity of light emitted to the observer from secondary light sources such as a light source and a reflective surface and a transmissive surface. The unit is cd/m2. Like luminous flux, it is a physical quantity expressed in conjunction with the sensitivity of the human eye. It is mostly used to indicate the brightness of display screens such as liquid crystal panels and PDPs.
Illuminance is an index indicating the brightness of light irradiated on a flat surface. The unit is lx (lux), sometimes also marked as lm/m2. It refers to the luminous flux per unit area of the luminous flux emitted by the light source to the planar object. Used to compare the brightness of lighting fixtures irradiated on a flat surface.
Brightness, illuminance, lumens, luminous flux
The relationship between luminous flux, luminous intensity, brightness and illuminance is simply summarized as follows: luminous flux divided by unit solid angle equals luminous intensity; luminous flux divided by unit area equals illuminance, luminous intensity divided by unit area equals luminance.
