is an electromagnetic wave, the speed is: 30 × 10000 km /s
Wavelength of 780 ~ 380nm (nanometers). 1 nm = 10 -9 th m

two. Spectral and color:
spectrum: red, orange, yellow, green, blue, indigo, violet
Infrared Wavelength: 620 ~ 780nm. UV wavelength: 380 ~ 420nm. As shown below:

wavelength of 780 ~ 620 ~ 590 ~ 560 ~ 490 ~ 450 ~ 420 ~ 380nm
Sunlight: the wavelength is 780 ~ 380nm, pure white.
Incandescent lamp: wavelength 780 ~ 400nm, the lack of purple, so a bit more red, yellow, light color after synthesis.
Fluorescent lamp: wavelength 750 ~ 310nm, the lack of red, green or slightly after it was synthesized green white.

three. The main role of light:
1 fixed and protection of light;
2 control and distribution of light, the light distribution required emergent;
3 decorative and landscaping;

four. lighting optical properties: lighting of the optical properties with three major technical data to illustrate that:
1 the spatial distribution of luminous intensity;
(2) Lighting efficiency;
3 . brightness distribution or light shielding angle;

V. luminous intensity of the spatial distribution

any lights light up all the space is not the same intensity, we can use the data or graphics to lighting in the space of luminous intensity distribution recorded, usually with a vertical coordinates to represent the lighting of the light intensity distribution to the origin as the center, the luminous intensity in all directions marked out with a vector, the vector connecting the endpoints, ie the formation of light intensity distribution curve, also called light distribution curve.

because most of the lamp shape is axisymmetric rotating body, the luminous intensity distribution in space is axisymmetric. Therefore, the axis through the light side to take Ren Yiping, to the plane of the light intensity distribution curve that lighting in the distribution of the entire space is enough. If the lighting luminous intensity distribution is asymmetric in space, such as a long strip of fluorescent lamps, you need to use a number of metering plane light intensity distribution curve to illustrate the spatial light distribution. Take the same long axis perpendicular to the lamp by lamp center line of the plane to drop C0 plane, perpendicular to the plane with the C0 and sagging lines by lighting the center of the plane of C90 plane. At least use the C0, C90 two plane light intensity distribution shows an asymmetric spatial distribution of light fixtures. In order to facilitate a variety of lighting the light distribution characteristics compared to uniform regulations to luminous flux of 1000 lumens (lm) of the imaginary light source to provide light intensity distribution data. Therefore, the actual light metering data should be provided light intensity value is multiplied by the ratio of the actual flux and 1000.

lighting intensity distribution is the use of light reflectors, light prism, grating or mask control scattered light to achieve. Reflector is a basic lighting control light components, the higher its reflectance, rules reflecting the stronger, more significant ability to control light. Anodized or polished aluminum, stainless steel mirror-emitting material is used. Accordance with the rules of law of reflection of the aluminum reflector geometry, size of careful design, installation, pay attention to precise positioning of light source, can get a variety of needs light distribution. Grid covered mainly from the light source, reducing direct glare effect. The light distribution through the grid is generally more narrow.

six. illuminance luminous intensity and spatial distribution of
Lighting layout and illumination calculation is an important part of lighting design, lighting design directly affects the quality. Point light source illumination calculation:

Where: E: illuminance
ΔS: light-receiving area
F: flux
IQ: luminous intensity
Formula shows that: a point source illumination generated by it to be face to face and the square of the distance, and angle of incidence is proportional to the cosine, and the reflective intensity is proportional to. When the light source is smaller than it is to be face to face distance of 1 /10 is considered a point source.

seven. lighting budget figure
Lighting budget figure used to express the number of lamps per unit area relationship. Given the same budget figure is usually light fixtures in several different suspension height, when the illumination requirements for 100Ix face when a surface area of ​​the required number of lamps, lighting as the basis for selection. If the face of the illumination is not required 100Ix correct, then the actual budget figure for the number of lamps multiplied by the number given on the ratio of actual illumination and 100Ix.

eight. Glossary: ​​
1. Flux: light source unit of time given to space, gives rise to the light feeling of energy. Light source is located in t seconds is the total radiated energy W, we put out the light radiation and radiation W elapsed time t as the ratio of luminous flux. Luminous flux is a measure of how much of an indicator light. To an F, in units of watts of light. Light watt unit is too large, common lumen (lm) as a practical unit, their relationship is a light watt = 683 lumens (lm). 1lm = 1cd · sr
Example: ordinary 40W fluorescent lamp luminous flux of 2200 lumens (100 hours)
1W power consumption of each domestic incandescent light flux generated about 12.5lm (4tlm)
2. Luminous intensity: is the space density of luminous flux, luminous flux per unit solid angle, which is a measure of the amount of light source intensity level. Unit candela (cd).
A candle's luminous intensity is about 1cd.
Domestic 100W incandescent luminous intensity of about 100cd.
3. Illumination (the illumination): is on the surface by the light flux density, that is, the flux per unit area. It is said illumination surface is illuminated by the light level of a volume. With E expressed in units of lux (Lx).
Example: natural light illumination approximately as follows:
100000Lx under direct sunlight sunny
10000Lx When sunny shade
20 Lx ; sunny corner room when
0.2 Lx ; Moonlight
100 ~ 200 Lx ; general office requirements of the illumination
General learning of illumination of not less than 75Lx
40W light bulb in an ordinary office illumination is about 1m below the 30Lx
1.3m below the 40W fluorescent illumination at about 90Lx

40W fluorescent lamp illumination of the surface of 7000cd /㎡

generally cloudy sky brightness average of 2000cd /㎡
5. Light effect: light-emitting efficiency, that is, light flux, and it occurred in the electric power consumption ratio, referred to as the luminous efficiency. Unit: lm /W, symbol: lm /W
Ordinary incandescent light efficiency of about 7 ~ 20lm /W
Straight tube fluorescent light efficiency is about 30 ~ 60lm /W, so better to use fluorescent energy saving than incandescent.

nine. light color and distortion
Light source color is a measure of quality is an important indicator. Including:
1 color table: direct observation of the occurrence of the human eye see color light.
(2) color: light exposure on the surface to produce objective results.
3. CRI: color of light shows and color under the sun than the value compared.
4 color temperature: is that a hot luminous object color.
X. scientific and reasonable lighting
1. Brightness contrast
When the ambient brightness and the center of brightness equal to or darker around, the visual acuity is best.
2 glare
In the visual environment, if the object is extremely bright or intense light.
Direct glare and reflected glare points.
Direct glare of light emitted by the light source shines directly caused by the human eye. Visual discomfort glare caused by reasons:
①. A high level of stimulation miosis;
②. As the cornea or lens and other eye tissue light scattering, in eye formation screens;
③. Depending on the stimulus screen by the high brightness, so that the state adapt to damage.
Direct glare of the light intensity and, following the most significant glare:
①. Light around the dark, the eyes adapt to the darker, more significant glare.
②. The higher the light intensity, the more significant glare.
③. Light source closer to the line of sight, the more significant glare.
④. Source of surface area the greater the number the more light, glare more significant.
Generally brighter than 160000cd /m have uncomfortable glare. Avoid methods:
Control the direction of projection light source, so that light can not be fired directly at the human eye, which requires light (or shade) has a protective angle.
Some lamps with transparent or translucent cover grille to cover the light source, because light leaving the area increases the brightness of each light to reduce light becomes soft but not dazzling.
Lighting glare definition:
When people feel the brightness of the eye directly over the ability to accept when they have no comfort, ability to decline and other adverse figuring reflected glare is light pollution, select the light source, light fixtures and lamps with improper or no time, often produce glare.