Extinction

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<MOVIE LINK MISSING> <MOVIE LINK>

Single anisotropic crystals under crossed polars exhibit extinction when the stage is rotated. The polarization colors decrease in intensity once for every 90 degrees of rotation. The particle passes through extinction four times during complete rotation of the stage. Many particles become black like the background at extinction. This is called complete extinction. It is shown in the two movies at the left. The upper movie is azurite and the lower movie is quartz. Both were taken with a 50x objective under crossed polars. Be sure to hide the movies when you are finished.