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SUMMARY:Electromagnetic surfaces from butterflies to battleships - Profess
 or J Roy Sambles\, School of Physics\, University of Exeter
DTSTART:20090513T151500Z
DTEND:20090513T161500Z
UID:TALK16465@talks.cam.ac.uk
CONTACT:Leona Hope-Coles
DESCRIPTION:*Question:*  _What do graceful\, flickering\, vividly iridesce
 nt\, tropical butterflies have in common with dull grey ponderous battlesh
 ips?_ \n\n*Answer:* _Structured materials give somewhat surprising electro
 magnetic responses._\n\nTaking little other than common cuticle\, loaded w
 ith a small amount of melanin\, butterflies have evolved some stunning mic
 rostructures in their wing scales. These structured surfaces\, often only 
 microns thick\, act as selective reflectors and polarizers as well as bein
 g sometimes very strong scatterers (white) or very strong absorbers (black
 ) of electromagnetic radiation. This use of structure in nature to give st
 riking effects when interacting with visible radiation is limited to diele
 ctrics. When it comes to synthetic structures we may also use metals. Stru
 ctured metals can also lead to unexpected effects such as negative index m
 aterials\, perfect lensing and ‘cloaking’. Even at very long wavelengt
 hs (microwaves and beyond) where metals are expected to behave as almost p
 erfect mirrors they can be structured to be almost perfect absorbers. \nTh
 is talk will illustrate briefly the wonderful structural colours of butter
 flies focusing primarily on some recent developments in the physics of str
 uctured metals for use at microwave frequencies. \n
LOCATION:Pippard Lecture Theatre\, Cavendish Laboratory
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