1、The essence of light ：
　　The essence of light is electromagnetism wave, is that a part of light of very little scope in entire electromagnetism wave table is a kind of form of energy, ; visible light is electromagnetism radiation table in can arouse person the part of eye vision. visible light have formed the part of so-called electromagnetism spectrum, electromagnetism spectrum exist in radio and television signal in, include infrared and ultraviolet radiation, x ray, nuclear radiation and universal radiation. in these electromagnetism radiations in, lustrous wave is animal and person eye evidently . this spectrum also include the 50 Hertz alternating currents of standard( the wavelength metre of six millions) with 380-780 wavelength nanometer( = 10-9 metre) the part of visible light. the wavelength of difference give person eye cause the color feeling of difference, from bonus and orange , yellow , green , blue , indigo( blue purple) arrive purple.

2、 Luminous flux ( light beam) ：
　　The light that sent for light source ( number) unit is lumen ( lm), for instance can lamp send 780( strip) light, total luminous flux( light beam) is 780 lumens.

3、Intensity of illumination ：
　　For the light passed through by each unit area, unit is lx. ( lm/m2)

4、 Brightness ：
　　Define with intensity of illumination nearly identical, if we each object is regard as the words of light source , so brightness is describe the shiny level of light source, intensity of illumination happen is each object is have been come to case history according to object with a plank, pawn certain light beam shine plank we speak plank have how many intensity of illumination, then plank will how many reflection of light beam go to person eye, is called as how many brightness of plank , so have following formula: brightness is equal to intensity of illumination multiply with reflectance. in put the intensity of illumination of a dark cloth and a calico with a room same one is identical, brightness is different.

5、 Light intensity ：
　　To pass through the light of 1 solid angles number,( know the density of light beam ). the unit of light intensity is the basic unit of photometry, is also the basic unit of international system of unit one. for the unit of reproduction luminous intensity, smooth standard ware is candle initially, so the unit of luminous intensity is called as early( candle ). develop , smooth standard ware afterwards along with science and technology alter for tengsten lamp, again alter for black body, 1948 the rear unit of luminous intensity name formally is Kan virtue pull ( cd ).

6、Dazzle , how control dazzle ：
　　There is brightness in field of vision very bright object or strong luminance contrast may arouse not comfortable or cause the phenomenon of visual reduction, is called as dazzle. cause person eye vision reduce dazzle name lose can dazzle; make one have the dazzle of unhappy sense to be called as not comfortable dazzle. have the method of two control dazzles normally: the brightness of 1 and direct control light source or weaken dazzle with pervious to light material; 2 , control dazzle with the shielding angle of lamps and lanterns 。

7、 The colour appearance of light source ( colour temperature) are colour temperature with psychology ：
　　Since people are used , the chromaticity with light source is equal or approximate complete radiation body absolute temperature describe the colour appearance of light source , therefore the colour appearance of light source is again called as light source colour temperature. colour temperature: light source project black body and the color of light radiate smooth hue under certain a temperature at the same time, the temperature of black body is called as this light source colour temperature. colour temperature have steady atmosphere below 3300 Ks, warm feeling; colour temperature in 3000 --5000 K is intermediate colour temperature, have straightforward feeling; colour temperature have cold feeling more than 5000 Ks. is the colour temperature shining of light source high do not give people high as brightness have the atmosphere of a kind of cloudy air; low colour temperature light source shine , brightness is a kind of hot and stuffy feeling to people high can have . in same space use two smooth aberration great light sources, its contrast will arise level effect, smooth colour contrast big , in get brightness level at the same time, may again get the level of smooth colour.
　　Colour rendering denotes the illumination of light source, shoot the objective effect that produces on object . if the object of all kinds receive shine effect and standard light source( black body or reshuffle sunlight) shine like, think the colour rendering of this light source good( the index of colour developing is colour or biography colour high ); otherwise, if object in receive according to rear color distortion, the colour rendering of this light source differ from ( the index of colour developing low ). colour rendering also fit develop.

8、 The physiological foundation of colour sleep: ：
　　The light that object sends makes thing resemble focusing in retina through cornea, room water, crystal and glass body , is nerve impulse from the sensitization cell transformation of retina, conduct the high-grade visual center of cerebrum again , produce vision, . the sensitization cell on human retina have two: rod form cell and awl form cell. rod form cell is , awl form cell very much for the understanding of light high low very much for the understanding of light. have only rod form cell work therefore under weak intensity of illumination, increase , awl form cell constantly along with brightness take affect increase , final awl form cell constantly take leading role. rod form cell can not distinguish color, only awl form cell just colored sleep.

9、Efficiency
a) , light source give out light efficiency denote a light source send luminous flux φ consume with this light source the P of electrical power than.
b) the light output ratio of light output ratio denote under rated condition measure lamps and lanterns project the lamps and lanterns and value of luminous flux own light source send out the ratio of mensuration value the sum of luminous flux.

10、Manufacturer the property that home can give which parameter explanation electric-optic source normally:
a) :specified voltage with specified current: will ask according to light source work need voltage and current. have electrical good power
b) in specified voltage and specified current operation) rated power: electric-optic source consume under normal operating conditions meritorious power
c): specified luminous flux with give out light efficiency: specified luminous flux is reflection electric-optic source send out under normal operating conditions luminous flux, call luminous flux normaliy; give out light efficiency denote electric-optic source each consumption 1 W electrical power send luminous flux. put forward in catalogue item luminous flux with give out light efficiency can along with time prolong drop.
d): life: the life of electric-optic source have whole life and effective life( point at electric-optic source give out light efficiency drop initial value at 70% o'clock use time) the
e): of mean life) the distribution curve of spectrum energy: spectrum energy distribution curve express electric-optic source radiate the smooth composition of each wavelength and the distribution condition of relative strength, this kind of press different wavelength place corresponding relative strength draw curve is called as electric-optic source relative spectrum energy spread curve.
f): colour temperature
g): colour rendering
Dodge frequently
h ): effect: electric-optic source supply power with alternating current source , make the change of periodicity because of alternating current, so electric-optic source send luminous flux also follow make the change of periodicity, this can make person eye produce dodge the feeling of kerosene. the luminous element of the light source of heat radiation hot inertia big, so twinkle feel not obviously, but the lamp of gas discharge relatively obvious.