Edens Harald E
Appl Opt. 2015 Feb 1;54(4):B26-34. doi: 10.1364/AO.54.000B26.
A photograph has been obtained of a natural fifth-order (quinary) rainbow. The photograph was acquired on 8 August 2012 with a digital camera and a polarization filter to maximize contrast of the rainbows with the background. The quinary rainbow, together with its first supernumerary, appears in a contrast-enhanced version of the photograph as broad green and blue-violet color bands within Alexander's dark band between the primary and secondary rainbows. The red band of the quinary rainbow is obscured by the much brighter secondary rainbow. A comparison with a numerical simulation using the Debye series confirms that the color bands of the quinary rainbow appear at the expected location. The numerical simulation produces a good match with the photograph for a droplet radius of 0.46 mm. The green band of the quinary rainbow is even faintly discernible in the unprocessed photograph, suggesting that under exceptional viewing conditions the green band of the quinary rainbow may be observed visually with the aid of a polarization filter.
已获得一张自然的五级（五重）彩虹照片。该照片于2012年8月8日使用数码相机和偏振滤光片拍摄，以最大化彩虹与背景之间的对比度。在照片的对比度增强版本中，五级彩虹及其第一道附属虹以宽的绿色和蓝紫色带的形式出现在主虹和次虹之间的亚历山大暗带内。五级彩虹的红色带被亮得多的次虹遮住了。与使用德拜级数的数值模拟进行比较证实，五级彩虹的色带出现在预期位置。对于0.46毫米的液滴半径，数值模拟与照片匹配良好。在未处理的照片中甚至还能隐约看到五级彩虹的绿色带，这表明在特殊的观测条件下，借助偏振滤光片可能肉眼观测到五级彩虹的绿色带。
