The average value of the illuminance on the surface is specified.
Unit: LX =lm/m
Symbol: EAV
Beam angle
On a given plane, the value of the luminous intensity of the vector is usually equal to the maximum luminous intensity value of 10% or 50% in the angle between the two vectors of the luminous intensity curve expressed in polar coordinates.
Candela
The standard light intensity unit is simplified as CD, and 1 Candela represents the luminous flux of 1 lumens in the solid corner.
Color rendering
The influence of lighting source on object color table is due to the conscious or unconscious comparison between the illuminant and the color table under the standard light source.
CRI (color rendering index)
The color rendering ability of light source to objects is called chromaticity. Color rendering index (Ra) is the main parameter to define the color rendering of light sources. The numerical range of Ra is 0~100, and the higher the Ra value, the better the color rendering of the light source. It is generally considered that Ra is more than 80, the color rendering of light source is excellent, and the color rendering of light source is generally less than 50 or less than Ra, Ra < 50, and the color rendering of light source is poor. The color rendering index of incandescent lamp is defined as 100, which is regarded as the ideal reference light source.
Color temperature
Color temperature is the most common indicator of spectral quality of light source. The color temperature is defined according to the absolute blackbody. The radiation of the light source is exactly the same as the radiation in the visible region and the absolute blackbody, at this time the temperature of the black body is called the color temperature of the light source. The characteristics of the low color temperature light source are the energy distribution, the red radiation is much more, usually called "warm light". After the color temperature is raised, the proportion of blue radiation is increased in the energy distribution, usually called "cold light". The color temperature of some common light sources is: Standard candlelight 1930K (Kelvin temperature unit); tungsten filament lamp for 2760-2900K; fluorescent lamp for 3000K; flash for 3800K; noon sun for 5600K; electronic flash 6000K; blue sky for 12000-18000K.
Glare
A visual object that causes discomfort or reduces the ability to observe the details or targets due to the discomfort of the brightness distribution or luminance range in the field of vision, or the existence of extreme contrast.
Illuminance
The illumination on the surface is the quotient of the D flux divided by the area dA of the surface element, That is
The symbol for this amount is E, The unit is LX, lx=lm/lm².
Lumen depreciation
Refers to the reduction of light output during the use of a light source.
Luminous efficacy
Refers to the amount of light emitted by a light source per kilowatt of energy consumed. Note that both the light source and the whole lighting system (including the lamp and the ballast) are determined, and the light efficiency of the lighting system is usually lower than the light effect of the light source.
Luminous flux
The luminosity derived from the effect of radiation on the standard photometric observer. For the vision, there is
In the form: dΦe（λ）/dλ = Spectral distribution of radiant flux
V（λ）= Spectral light (visual) efficiency
Km = The maximum value of the spectral (visual) efficiency of radiation,
The unit is a lumen per watt (LM W-1).
In monochromatic radiation, the Km value is 683lm/ W (lambda m=555nm) under
the condition of bright vision.
The symbol of this quantity is LM, 1lm=1cd = Sr.
Luminous intensity
The luminous intensity of the light source in a given direction is the amount of D flux transmitted by the light source in the solid corner D ohm of this direction divided by the quotient of the solid angle element. That is,
The symbol of this quantity is l, and the unit is Candela (CD) and lcd=lm/1sr.
Lux
It is the standard unit of illumination. 1 lux indicated that the luminous flux was 1 lumens on the surface of 1 square meters.
