In this blog we have already seen photos of spiderwebs scattering rays of light, and even a thistle seed showing spectral colours. Now I would like to contribute to this collection with another possible source for observing this optical phenomenon: cat's hair. The pictures attached show the dark Sámán (of Mónika Landy-Gyebnár) and the white Manci (my cat). When light comes from the appropriate angle, their fur can display the colours of the rainbow surprisingly clearly. Please, click the images to see it better. Full size photos of Sámán's and Manci's shining hair are also available.
The other photo is another "animal test". Given that birds' feathers have a very regular structure, I was interested whether they show corona-like diffraction if we place one in front of a light source. I found that the repetitive structure of barbs, barbules and tiny hooks interlocking on them create beautiful interference patterns. This picture - somewhat out of focus - shows an owl's feather (a secondary from its wing) with a lamp behind it. The pattern is curved because the feather itself has a bent surface. Further images: #1, #2, #3