Some time ago, James sent me this link:
https://www.youtube.com/watch?v=fQrS6lo5xjE
I finally got around to trying it. 40x crossed polarizers on a Diaphot.
Getting good video will be a bit more challenging!
This is E7 nematic liquid crystal with a couple of crystals of cholesteryl benzoate dissolved into it (heated) to make it a chiral nematic.
The raw crystals of cholesterol exhibit circular birefringence - rotating the crystal between crossed polarizers doesn't show an axis of extinction, or any change with rotaiton, for that matter. Heating it to the melting point (150°C) makes it go isotropic (no polarization properties), then cooling, with or without the E7 makes a "waveplate" with circular retardance instead of linear.
I'll be documenting this more and putting it on my site in the near future.
Happy Holidays!
Mike
chiral nematic liquid crystal
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