Light refraction patterns. These diagrams are from 'Treatsie on light' (1690) by the Dutch astronomer and physicist Christiaan Huygens (1629-1695). It

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Light refraction patterns. These diagrams are from 'Treatsie on light' (1690) by the Dutch astronomer and physicist Christiaan Huygens (1629-1695). It was in this book that Huygens first proposed his wave theory of light.

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