Tuesday, 19 February 2008

animal optics



Animal Optics

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 S�m�n (of M�nika Landy-Gyebn�r) 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 S�m�n'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


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