Multilayer thin-film structures in the wings of a butterfly; Papilio crino produce a colourful iridescence from reflected light. In this investigation, scanning electron microscope images show both the concave cover scales and pigmented air-chamber ground scales. The microstructures with the concavities retroreflect incident light, thus causing the double reflection. This gives rise to both the colour mixing and polarisation conversion clearly depicted in the optical images. The result of the numerical and theoretical analysis via the CIELAB, and optical reflection and transmission of light through the multilayer stacks with the use of transfer method show that the emerging colouration on the Papilio crino is structural and is due to the combination of colours caused by multiple bounces within the concavities. The butterfly wing structure can be used as the template for designing the photonic device.

中文翻译：

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综合分析 Papilio crino Fabricius，1792 翅膀的逆向反射。

蝴蝶翅膀中的多层薄膜结构；Papilio crino 从反射光中产生五颜六色的虹彩。在这项调查中，扫描电子显微镜图像显示了凹面覆盖鳞片和着色气室地面鳞片。具有凹面的微结构回射入射光，从而引起双反射。这产生了在光学图像中清晰描绘的颜色混合和偏振转换。通过 CIELAB 进行数值和理论分析的结果，以及使用转移法通过多层堆叠的光反射和透射结果表明，Papilio crino 上出现的颜色是结构性的，是由于颜色组合引起的凹面内的多次反弹。