Correlation between illuminance measured by illuminance meter and illuminance unit
(1) When a light source shines on an object, we can measure which part is emitted by the light source (Lumvnance? D brightness) or which part is reflected by the object (Illuminance? D illumination).
(2) Illumination depends on the reflective characteristics of the object. It's very similar to a photo in that it measures only reflected light. Its common unit is lux.
(3) However, an EL lamp is a light source: it should be expressed in brightness units, which are fL (foot-lambert) or cd/m2, also known as "nits". Some engineers prefer to use fL, while international standards organizations commonly use nits. The formulas for converting nits and fL are: 1nits×0.2919=1fL; and 1fL×3.426=1nits [Note; These factors are derived from pi (π) and m2/ft2 (0.0929).
(4) Obviously, using lux is an incorrect unit, and it cannot be converted from lux to other units. 1 Lux = 1 lumenpersquaremeter= 0.0929 footcandle 1 footcandle= 1lumen persquarefoot =10.764 Lux1 foot Lambert= 3.426 candelas per squaremeter (nit) 1nit (candelas per square meter) = 0.2919 footLambert
Luminous flux
Luminous flux: The rate of light energy emitted by a light source or the flow rate of light (Flowarte). It is the basic quantity that describes the ability of a light source to emit light. The unit is Lumen. For example, a 100-watt (W) light bulb can produce 1,750lm, while a 40W cool white fluorescent tube can produce 3,150lm of luminous flux. According to the definition, 1lm is the luminous flux emitted by a uniform point light source with luminous intensity (l) 1cd within a solid angle of 1 steradian.
light intensity
Luminous intensity (Luminousintensity, Candlepower): Luminous intensity, referred to as luminosity, refers to the luminous flux emitted from a solid angle (unit: sr) of the light source, that is, the distribution density of the luminous flux emitted by the light source or lighting fixture in a selected direction in space. The unit is candlelight (CandleorCandela, cd). A light source with a luminous intensity of 1cd can emit a luminous flux of 12.57lm. Illuminance: The density of light flux received on the illuminated plane, which can be measured by the light flux per unit area. A luminous flux of 1lm is evenly distributed on a surface of 1 square meter (m2), which produces an illumination of 1 lux (Lux, environmental technology > illuminance meter); a luminous flux of 1lm falls on a surface of 1 square foot (ft2), and its illumination value is 1 footcandle (Footcandle, fc).
