Giant Owl Butterfly Scale

pwnell · Post by **pwnell** » Tue Aug 21, 2012 11:47 pm

I tried to see what kind of resolution I can get with my setup using one single scale from this beautiful butterfly. The first image is an uncropped version taken with a 60x/1.35 oil objective and 2x magnification changer. The second is about a 100% crop. The tiny spore-like protuberances within the grid like pattern I measured to be about 290nm (0.29 µm). I think this is not too bad considering I am close to the theoretical limit of my 1.35 objective, which is about 0.23 µm. To get better I presume one needs a confocal microscope or a TEM / SEM.

ZereneStacker PMax

100% crop

Compare these to these photographs:
http://www.learnaboutbutterflies.com/An ... ineton.htm

Mitch640 · Post by **Mitch640** » Wed Aug 22, 2012 5:23 am

That's beautiful. Do you think it is grown as a mesh with holes, or is it one piece with the space between filled with a clear membrane?

pwnell · Post by **pwnell** » Wed Aug 22, 2012 8:27 am

I am no expert on this but I do believe there is no membrane. The spacing between the ribs is what causes the irridecence, ie it diffracts the light.

rjlittlefield · Post by **rjlittlefield** » Wed Aug 22, 2012 8:33 am

That is a beautiful image!

Mitch, probably no membrane. SEM shots of lepidoptera scales consistently show an open network. See for example http://en.wikipedia.org/wiki/File:SEM_i ... view_4.JPG, linked from the article http://en.wikipedia.org/wiki/Lepidoptera#Scales.

--Rik

Mitch640 · Post by **Mitch640** » Wed Aug 22, 2012 8:38 am

Rik, that's amazing. The question just came to me as I was writing a reply. I had no idea. The scales do not supply lift, but now it leads me to ask if air molecules are to big to fit through the holes? I don't have any idea of the scale of things. [I guess that's silly, come to think of it, or we would be able to see them in the eyepieces.] LOL

pwnell · Post by **pwnell** » Wed Aug 22, 2012 8:40 am

Air can easily move through the holes, as an air molecule is about 4 x 10^-10 m in diameter.

rjlittlefield · Post by **rjlittlefield** » Wed Aug 22, 2012 8:48 am

The molecules are about 1000 times smaller. Google search on "diameter oxygen molecule" etc turns up a small range of values. http://www.getnitrogen.org/pdf/graham.pdf has a detailed discussion. Roughly speaking the diameters of O2 and N2 are around 3 angstroms = 0.0003 microns.

Oops -- I see Waldo posted while I was off reading too much!

--Rik