Near-Field Photometry: A New Approach
Near-Field Photometry: A New Approach
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近场光度测定：一种新方法
DOI：
10.1080/00994480.1993.10748029
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
I. Ashdown
中科院分区：
文献类型：
--
作者：
I. Ashdown
在“近场间接照明计算研究”中，Mistrick和English15研究了照明计算程序模拟间接照明器附近天花板亮度的能力。他们得出结论：“目前在近场应用中利用远场光度数据的计算实践并不能准确地模拟间接光源附近的天花板亮度。为了提高照明计算的技术水平，我们必须研究允许我们精确地模拟近场环境的可替换的测量和计算过程。“曾多次尝试制定此类程序。Stannard和Zero23开发了应用距离测光，将灯具建模为等效点源。Franck 4和Lautzenheiser等人10将灯具建模为点光源阵列。Verbeck和Greenberg 24以及Ngai 18研究了将灯具建模为点光源阵列的理论方面，但没有提供任何测量程序。应用距离测光为特定的测量平面提供近场环境的近似值。Bradford和Stannard 2以及Ngai等人19证明，可以根据光度数据合理地内插测量平面之间以及与测量平面平行的平面的照度。然而，这些数据不能外推到相对于那些测量的平面倾斜的平面或与灯具体积相交的任何平面。16将灯具建模为点光源阵列需要知道每个光源的发光强度分布和空间位置。然后，可以通过使用平方反比定律来计算每个源的光通量贡献来确定近场环境中的表面的亮度，Ngai 18证明，如果每个点的亮度分布函数已知，则可以计算灯具表面上的每个无穷小点的发光强度分布。不幸的是，这是不可能准确地测量这些功能，因为我们被限制在有限区域的亮度测量。如果表面是凸的或凹的，则该区域以倾斜角度部分地遮挡自身，或者被灯具的其他部分遮挡。
In" A Study of Near-Field Indirect Lighting Cal culations," Mistrick and English15 investigated the ability of lighting calculation programs to model ceiling luminances near an indirect luminaire. They concluded," The current calculation practice of utilizing far-field photometric data in near-field applications does not accurately model ceiling luminances near an indirect luminaire... to advance the state-of-the-art in lighting calculations, we must in vestigate alternative measurement and calculation procedures that would permit us to accurately model the near-field environment." There have been several attempts to develop such procedures. Stannard and Brass23 developed applica tion distance photometry, which models the luminaire as an equivalent point source. Franck4 and Lautzenheiser, et al. 10 modeled the luminaire as an array of point sources. Verbeck and Greenberg24 and Ngai18 examined the theoretical aspects of modeling the luminaire as an array of point sources, but did not offer any measurement procedures. Application distance photometry offers an approx imation of the near-field environment for specific planes of measurement. Bradford and Stannard2 and Ngai, et al. 19 demonstrated that the illuminance of planes between and parallel to those measured can be interpolated reasonably from the photometric data. However, these data cannot be extrapolated to planes that are tilted with respect to those measured or to any plane that intersects the luminaire volume. 16 Modeling the luminaire as an array of point sources requires that the luminous intensity distribution and spatial location of each source be known. The il luminance of a surface in the near-field environment can then be determined by using the inverse square law to calculate the luminous flux contribution of each source, Ngai18 demonstrated that the luminous intensity distribution of each infinitesimal point on the surface of a luminaire can be calculated if the luminance distribution function of each point is known. Unfor tunately, it is not possible to accurately measure these functions because we are limited to measuring the luminance of finite areas. If the surface is convex or concave, the area partially occludes itself at oblique angles, or is occluded by other parts of the luminaire.