Bragg Gratings and my attempts to understand them

You can just about see the defraction through this feather. The rainbow effect is actually more obvious with the naked eye.

That feather looks like this under a microscope. Now I wonder is the effect from the ribs or the very fine fur growing off them?

I read somewhere that it was possible to make silicone moulds of holograms. So I've decided to try to mould that feather. Possibly to reproduce in metal as a reflector Bragg.

And after a couple of hours this!

Look at the detail it captured! Next is to try Rochelle's Salt process to apply a silver coating. The grooves are very high ratio so I have doubts it will work. Stay tuned for more!

Foundry Refurbishment day 2

I felt like Howard Marks or Howard Hughes or no, Howard Carter when I uncovered the earth furnace. It hadn't collapsed so things are looking good

After a bit shoveling and scraping it's back to looking good. I stabilised the linings a bit by repacking in-between the clay mortar. The existing stuff is bisque fired at this stage. 

l will let this dry for the day and make a small charcoal fire in it later. BBQ anyone?!