The image above shows why. While it looks pretty, the ripples that you see are not a natural feature of the bee's compound eye (the underlying hexagonal structures in the image). The ripples are caused by putting the sample into a vacuum prior to drying it sufficiently and are the result of water evaporating from the surface, causing significant damage to the surface.
All biological specimen preparation for microscopy aims to preserve the sample as close to the living state as possible. With light microscopy, imaging live, dynamic samples is achievable and routinely used. This is not possible with electron microscopy due to the necessity for high* vacuum requirements.
As such, samples must be prepared to withstand the vacuum conditions. This requires removing or stabilising all water in the sample. However, dehydration has the effect of coagulating proteins, molecules and other cellular and extracellular components, changing their arrangement and structure. Prior to dehydration, fixation is applied.
Physical fixation can be applied in the form of rapidly freezing the sample, which can then be imaged in its frozen state with specialised cryo-microscopes. Alternatively, the sample can be dehydrated at -90 degrees centigrade and then brought back to room temperature once all the water has been removed.
Chemical fixation involves the use of chemicals that form bonds between biological structures, preventing their movement when the water is extracted.
The samples are often embedded in a hard resin and sectioned (50-200 nm thick) for transmission electron microscopy or dried for scanning electron microscopy.
The image shown is a false colour scanning electron micrograph of artefacts produced as a result of inadequate dehydration and drying. The micrograph was taken by myself and the false colour applied later. These artefacts are attractive but obscure the biological tissue underneath, which may lead to incorrect conclusions about the structures being studied.
*High vacuum is require in most cases, exceptions being variable pressure/environmental scanning electron microscopes that can work at low vacuum with some cost to resolution.