Illuminance meter brightness and illuminance unit conversion relationship
(1) When a light source shines on an object, we can measure which is emitted by the source (Lumvnance? D brightness) or which is reflected by the object (Illuminance? D illuminance).
(2) Illuminance depends on the reflective properties of an object. It is very similar to a photograph 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 units of luminance, i.e., fL (feet Lambert) or cd/m2, also known as "nits". Some engineers prefer fL, while the International Standards Organization uses nits. nits is converted to fL by the formula: 1nits x 0.2919 = 1fL; and 1fL x 3.426 = 1nits [Note; these factors are derived from pi(π) and m2/ft2 (0.0929).
(4) It is clear that the use of lux is an incorrect unit, nor can it 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 (Luminousflux): that is, the rate of light energy radiated by a light source or the rate of flow of light (Flowarte), for the description of the ability of the light source to emit light the basic amount of light, the unit for the lumen (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. By definition, 1lm is the luminous flux emitted by a uniform point light source of luminous intensity (l) 1cd at a stereo angle of 1 spherical degree.
Luminous intensity
Luminous intensity (Luminousintensity, Candlepower): Luminous intensity referred to as luminous intensity, refers to a stereo angle from the light source (unit sr) radiated by the luminous flux, that is, the light source or lighting fixtures emitted by the luminous flux in the space of the selected direction on the distribution of density in the unit of candela (CandleorCandela, cd). Luminous intensity of 1cd light source can radiate 12.57lm of luminous flux. Illumination illuminance (luminance): illuminated plane to receive the density of luminous flux, available per unit area of luminous flux to measure. 1lm of luminous flux uniformly distributed in 1 square meter (m2) of the surface, that is, to produce 1 lux (Lux, environmental technology> illuminance meter) of the illuminance; 1lm of the luminous flux falling on the surface of 1 square foot (ft2), the illuminance value of 1 foot-candle ( Footcandle,fc).
Luminance brightness or luminance (luminance, Brightness): when the human eye visualization of something seen, can be expressed in two ways: one for higher luminous value such as light sources or lamps, directly to its luminous intensity to express; the other is used for its own non-luminous only reflective light, such as: indoor surfaces or general objects, expressed in terms of luminance. Brightness that is illuminated per unit area in a certain direction or reflected luminous intensity, to show the difference between light and dark illuminated, the metric unit of candela / square meter (Candela / m2, cd / m2) or nits (nit), the British unit of feet Lambert (Footlambert, fl).
(illuminance meter) Brightness and illuminance unit conversion relationship Luminous flux: Symbol Φ, unit lumens Lm, indicating that the luminous body per second kind of light emitted by the sum of the amount of light, that is, the luminous flux Light intensity: Symbol I, unit Candelas cd, indicating that the luminous body in a particular direction unit stereo angle of the luminous flux emitted by the luminous body Illumination: Symbol E, unit lux Lm/m2, indicating that the luminous body irradiation in the light of the illuminated object on a unit area luminous flux Brightness: Symbol L, unit nits cd/m2, illustrates the luminous flux emitted by the luminous body in a specific direction unit stereo angle unit area Luminous efficacy: unit lumens per watt Lm/w, illustrates the ability of an electric light source to convert electrical energy into light to the luminous flux emitted divided by the power consumption to be expressed.
