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In August 1811 , François Arago reported that if a thin plate of mica was viewed against a white polarized backlight through a calcite crystal , the two images of the mica were of complementary colors ( the overlap having the same color as the background ) .
 François Arago
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 François Arago