In the road lighting LED lights for the fog penetrating understanding of a great misunderstanding. Most people have always thought that the LED lights penetrating sodium than traditional lighting penetration is low, this is a wrong understanding. Most people are seeing some of the information from the network or to see some of the sensory feel on the road, and did not do scientific assessment and analysis, so that the penetration of LED street light is poor. In this article the analysis of this situation as a science.
That is all the lights only within this band of light have use value, out of the range of the human eye is unable to recognize. This paper analyzes the penetration only be carried out within this range.
Effect of fog and rain on the road lighting is mainly reflected in: drop penetrating mist of suspended particles and raindrops on the scattering of light caused by the direct result of the decline in the intensity of illumination. Airborne particles of light scattering theory is mainly based on Rayleigh scattering law and the meter - Debye scattering law, the scope of application of the law of scattering in the visible range as follows: r represents the radius of particulate matter; when r <Rayleigh scattering when 0.037μm law, obey meters when r> 0.037μm - Debye scattering laws. Rayleigh scattering law of light scattering effect and wavelength are related m - law of Debye scattering light scattering effect is not affected by wavelength. Fog and rain radius of suspended particles are distributed as follows: Fog is 2.8μm ~ 10μm, raindrops 10μm ~ 5000μm. Since larger particles than 0.037μm, so the scattering of light rain and fog and is not related to the wavelength. That road lighting lamps and penetration is the color does not matter. LED penetration and sodium is the same.
Traditional empirical knowledge may feel strong penetration of sodium, this is just an emotional understanding. Because sodium light is dark yellow, led light is white, and white fog. Found on white background sodium definitely much easier than finding led lights on white background.
When road illumination particularly fog, color rendering index can not be ignored. Sodium lamp color rendering index of 17 common LED color rendering index is about 65-80. Since the blue spectrum deletion sodium sodium directly in lower color rendering index. Blue body irradiation sodium would appear black, that when sodium light impinges on the blue object, the object does not reflect light. This will result when pedestrians wearing blue clothes with blue or obstacles on the road, under the irradiation of sodium lamp, the reflected light does not emit a blue object, an object in the fog will drown in blue background light, people will not see blue objects. This will lead to traffic accidents. If you use LED lighting would not be the case.
In addition, LED lights are also a number of stars and integrated LED points. Multiple LED light-emitting area is large, low surface brightness, and integrated package LED high brightness light-emitting surface area is small. Thus, integrated packaged LED directivity of the irradiated surface has certain advantages that make it easy to see in the fog weather extending direction of the road in the fog lighting will be an advantage.
In summary, the traditional view is that sodium than the LED lights in the fog penetrating awareness of the existence of an advantage biased, this article discusses from a theoretical point of sodium does not have an advantage in penetrating than the LED lights, but from the viewpoint of color rendering index, the LED lights in the fog kind distinguish better; in addition, the surface emission intensity from the light source to consider, integrated package LED light source for lighting and fog day advantage.
