They have developed a complicated three-dimensional photonic structure on their wing scales in order to efficiently reflect white light.
At the same time, this structure is very porous and is confined within a thin layer of about 10 µm, about one fifth of the thickness of ordinary white paper, which makes it very light and therefore advantageous to fly.
Researchers of the University of Fribourg and their collaborators wanted to understand how this fascinating structure is optimized, for which they needed a faithful 3D image. However, conventional microscopy techniques providing enough spatial resolution such as electron microscopy required the sample to be cut for imaging consecutive slices, causing damage of the structure during the process.
Image: Cyphochilus white beetle source: PSI