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chiral nematic liquid crystal

 
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mtuell



Joined: 11 May 2016
Posts: 275
Location: Tucson, AZ

PostPosted: Mon Dec 25, 2017 11:24 am    Post subject: chiral nematic liquid crystal Reply with quote

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
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Smokedaddy



Joined: 07 Oct 2006
Posts: 1163
Location: Phoenix, Arizona

PostPosted: Mon Dec 25, 2017 12:35 pm    Post subject: Reply with quote

Interesting. glad you finally were able to experiment with it. Just curious, where to you get the cholesteryl benzoate?

Cheers,
-JW:
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carlos.uruguay



Joined: 23 Feb 2012
Posts: 4989
Location: Uruguay - Montevideo - America del Sur

PostPosted: Tue Dec 26, 2017 6:11 am    Post subject: Reply with quote

Nice
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