Lighting Knowledge


Lighting technology is like scientific discipline and any other technology, which have specialty terms. This some special terms and ideas are used for defining the characteristic of light and lamps and lanterns and measuring the unit to unitize. The following are some important lighting terms.


Light and radiation

Light is a brightness electromagnetism radiation that human eye can be perceived. It also can be said the part that the human eye can be seen in the electromagnetic radiation spectrum. The wavelength of this part is distributed 360 to 830mn; only occupy electromagnetic radiation small part very of spectrum that knows already.


Luminous flux, Φ

Unit: lumen, lm

Called the luminous flux by all radiation energy launched and perceived by the human eye of a light source.


Luminous intensity, I

The light source is in some size of luminous flux to the solid angle of one party.


Unit: candela, cd


Generally speaking, the light source will radiate its luminous flux with different intensity in different directions. Called luminous intensity in the visible light radiation intensity emitted of the specific direction


Illuminance, E

Unit: Lux, lx

The intensity of illumination is luminous flux and shown up’s ratio.

It is the area of one square meter that the intensity of 1 lux illumination is distributed for the luminous flux of 1 lumen evenly in the area.


Luminance, L

Unit: cd/

             A light source or a brightness shown up mean its unit surface is in some upward density of luminous intensity of one party. It also can be said this light source or the bright degree shown up that the human eye perceives.


The important examine all formula:

I, luminous intensity [cd]= the luminous flux in the solid angle/ in the solid angle Ω[sr]

E, illuminance [x]= leave the luminous flux on some area [lm]/the shone area[]=luminous intensity [cd] /(distance[m] )2

L, luminance [cd/]= luminous intensity [cd] / area of showing up of the finding []
    η luminous efficacy [lm/W]= produced of luminous flux [lm] / consume the electric power[W]

Luminous efficacy, η

Unit: lm/W

Represent the light source and change the electric energy consumed into mere efficiency.


Color Temperature

Unit: Kelvin, K

One color temperature of light source defines for instead of have the same color of black body radiator's own absolute temperature value. This temperature can find their corresponding particle at the Plonk orbit at the picture. The temperature of the black body radiator is higher, the blue compositions are the more in the light spectrum produced in its radiation, the less reradiator is higher, the blue compositions are the more in the light spectrum produced in its radiation, the less red compositions stand opposite each other too. Regard sending out all as the warm and white ordinary white heat bulb as the example, color temperature its 2700K, and the color temperature of fluorescent lamp of light on day time its 6000K.


Light color

The light color can be shown with color temperature simply. Light color can divide into three big classes mainly.


Warm color< 3300K

Demitint3300 to 5000K

Day light color> 5000K


Even the light color is the same, light kind perhaps make up with have performing color behavior differencing very heavy because their send out light spectrum.


Color rendering

It is generally acknowledged artificial light sources should let human eye perceive color correct, as see the things under the sunlight. Certainly this needs to look at occasion and purposes used and have different demand degree. Namely performing the color characteristic of light source, called it general color rendering index. Average to color rendering index color that show instead of shine color relative difference of the two under according to light source until some light source shine for target. Evaluation for in order to according to light source and according to 6169 eight color that stipulate make comparisons and quantize their differences one by one on the kind in DIN light source of awaiting measuring separately law of number value its. The smaller the difference is, namely represent and await measuring performing the color of light source is the better, average to perform color index Ra can let various kinds of colors demonstrate for 100 light source like according to the color that the light source shine, the lower Ra value is, the more distorted the color appearing is.


Luminaire efficiency

Luminaire efficiency is an important standard of the energy efficiency that is used for assessing the lamps and lanterns. The value its equip with luminous flux that lamps and lanterns send out of light source divided by load with light source itself house send out trader value, luminous flux of income.


Invisible Light

To the visible light, the invisible light called the visible light in 360 electromagnetic radiation of getting beyond 830nm. What the electromagnetic wave that the wavelength is smaller than 360nm is understood for common people the most is an ultraviolet ray, other has x ray, r ray, universe line, the electromagnetic radiation greater than 780nm is infrared ray and radio wave, etc.



The light is called the spectrum in accordance with the distribution of the size order of the wavelength. Each light source can make up but demonstrate their power spectrum distribution at spectrogram in accordance with their wavelength. The spectrum energy of sunlight and incandescent lamp is distributed for the continuous curve, and it is the non- continuous curve to generally put the electric light.


Incandescent lamp

The incandescent lamp is the early ripest artificial electric light source. It is the principle of utilizing filament to set up an electric circuit and generate heat to give out light to give out light. Generally speaking, the luminescence efficiency of the incandescent lamp is relatively low, the life span is relatively short too, but it is relatively convenient to use.


Gas discharge lamp

The luminescence principle of this kind of light source is excited by the electron and given out light for the gas between its two electrodes. Can divide and put the electric light for the low-voltage gas, such as fluorescent lamp, high-pressure gas, mercury vapor lamp, high-pressure sodium and reply the metal light.



LED is made of special material p-n diode. Obeying it to the bias voltage, the electron is while flowing the joint, will give out light during the process of combining again but eliminate. Small bulk, give out light efficiency is not originally high. But develop rapidly in recent years, has already popularized the traffic signal lamp, indicator lamp in suitable occasion, even suitable for some lighting uses of special occasion too.

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