From: jsavard@ecn.ab.ca   
      
   On Monday, October 26, 2020 at 7:35:22 AM UTC-6, Jeroen Belleman wrote:   
   > While playing with polarizing filters, I found a plastic ruler   
   > that turns out to rotate the polarization angle of the light   
   > passing through it by almost exactly 90 degrees. The ruler is   
   > of a 1mm thick colourless plastic, rather flexible, clearly   
   > not the usual polyethylene or polystyrene. It does not itself   
   > polarize light, it just rotates it. The angle of rotation does   
   > not seem to depend on wavelength. It's made in China.   
   >   
   > What plastic could this be?   
      
   As has been noted, optical activity is quite common in plastics.   
      
   If you put a mildly crumpled cellophane wrapper from a pack of cigarettes   
   between two polarizing filters, you will see beautiful colors.   
      
   John Savard   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)