Study On The Impact Of Mesopic Vision On Visual Effect

With the acceleration of the construction of highway,the number of tunnel is more and more.Tunnel lighting system is the maximum overhead of a tunnel system.How to ensure the safety of tunnel lighting at the same time to achieve energy-saving,is a problem that people pay special attention to.The brightness of mesopic vision between the photopic and scotopic,that is generally considered range of 0.001-3cd/m2.Most of the lighting in the tunnel belong to mesopic vision.There is no measure measuring instruments for mesopic vision.So this paper proposes an mesopic visual equi、valent illumination factor to realize the illumination conversion between photopic illumination and mesopic.In order to study whose light efficiency higher for HPS and LED,the paper measures the human eye visual effects for two kinds of lamps,in the mesopic lighting with different visual environment.The research results of this paper will be helpful to the optimization of tunnel lighting standards,and guide the selection of the tunnel light,and realize the best lighting effect with the least energy.The paper analysed the typically mesopic models,and find a model suitable for tunnel lighting.Based on a number of recent mesopic photometry studies,an equation is deduced for the tramsition from the photopic illumination to mesopic equivalent illumination.and one kind of modified coefficient for different light sources under mesopic light levels is studied.The modeified coefficient can be used to calculate the mesopic equivalent illumination by using the measuring results of photopic illumination.The results show that in the mesopic light levels,modeified coefficient of LED is greater than 1,and HPS is less than 1.This means that in the mesopic light levels,LED luminous efficiency is higher than HPS.And tunnel lighting brightness standards should distinguish different lamps and lanterns.The paper tests the reaction time of the human observing targets for the HPS and LED lights in the mesopic light levels.The results indicate the effeet of light level,visual angle and eccentricity on detection rate and reaction time at mesopic region,and compare the HPS and LED reaction time under different lighting conditions,to find a source which is suitable to tunnel lighting.The experiment tunnel uses LED for tunnel lighting and measure the tunnel pavement illumination real-time.And the tunnel uses the modeified coefficient to calculate the mesopic equivalent illumination by using the measuring results of photopic illumination,so as to better achieve energy-saving tunnel.