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能见度一般为人眼视觉能够观测目标物的最大估计水平距离.能见度的观测和预报已经广泛的应用于气象预报、环境污染分析、交通运输等各个领域.现有的能见度观测方法主要分为散射式与透射式.其中数字摄像式能见度观测方法最贴近能见度定义,随着数字摄像技术的发展,加快了数字图像能见度的测量方法的研究与应用.但在利用数字摄像进行夜间能见度观测量过程中不可避免的受到不同天气背景光、光源灰度等影响从而造成能见度测量不稳定,观测结果精度低、观测范围较小.已知利用双光源的稳定性可以保证能见度的测量精度,大多数研究都是通过使用白光源的角度来解决能见度的测量不稳定问题.本文从准单色光源的角度出发,通过不同频段光源对能见度的穿透能力不同,在可见光范围内对不同频段光源的穿透能力进行特性分析.在已有的双光源基础上,提出了一种改进的恒温双色光源夜间能见度观测方法,实现在不同天气状况下,对能见度的高精度、大范围观测.通过设计恒温双光源,消除了环境温度变化对光强的影响;恒压恒流模块保证双光源光强一致性;利用积分球保证光强的均匀性;根据不同频段光源对能见度的穿透能力不同,选用双色光源实现高精度、大范围能见度的有效测量.在恒温双色光源的能见度观测系统中进行一系列的实验验证,实验结果表明两个光源的一致性达到0.99,能见度不好时,蓝光到达相机的光强弱,红光的测量结果接近真值;晴天时夜间能见度良好,蓝光透射率差值大,有利于提高信噪比,双光源为蓝光的标准差36.90,蓝光的测量结果接近真值.当观测极限为15000 m时,进行1个月的实验观测,通过与真实值进行比较,所提出的改进恒温双色光源夜间能见度观测方法能够很好的在能见度观测极限范围内进行准确的测量.“,”Visibility is the maximum horizontal distance that can be seen .Its observations and forecasts have been widely used in various fields of weather forecasting ,environmental pollution analysis ,and transportation . The existing visibility estimation methods are mainly divided into scattering type and transmission type . Among them ,digital camera method for measuring visibility is the closest to the definition .With the develop-ment of digital camera technology ,the research and application of digital camera measurement methods have been accelerated .However ,in the process of nighttime visibility measurement by using a digital camera ,the measurement is inevitably affected by the background light ,the gray level of the light source ,etc .,resulting in unstable visibility measurement , low precision of observation results and small observation range . It is known that the accuracy of visibility measurement can be guaranteed by using the stability of dual light sources .Most studies have used a white light source to solve the measurement visibility instability problem . From the perspective of quasi-monochromatic light sources ,the penetration ability of light sources in different frequency bands is different .In the visible range ,the characteristics of the penetrating ability are analyzed . Based on the existing dual light sources ,a method for nighttime visibility estimation based on constant temper-ature two-color light sources has been proposed ,which realized high-precision and wide-range visibility estima-tion under different weather conditions .By designing the constant temperature duallight sources ,the influence of ambient temperature change on the light intensity is reduced .Constant voltage and the constant current module are used to ensure the consistency of the dual sources light intensity .The integrating sphere is used to ensure the uniformity of the light intensity .According to different penetrating powers of different frequency bands ,the two-color light sources are used to achieve high-precision and wide-range visibility .A visibility observation system based on constant temperature two-color light sources has been established .A series of experiments have been carried out .The experimental results show that the consistency of the two light sources reaches 0.99 .When the visibility is not good ,the light intensity of the blue light reaching the camera is weak , and the measurement result of the red light is close to the true value .When it is sunny ,nighttime visibility is good .At this time ,the difference in blue transmittance is large ,which is beneficial to improve the signal-to-noise ratio .The standard deviation of the blue light source is 36.90 ,and the measurement result of blue light is close to the true value .When the visibility range is up to 15000 m ,one month of experimental observation is performed . By comparing with real values ,the proposed method has great accuracy within the visibility range .