In 2016, hoping to decrease the amount of counterfeit money in their economy, the government of India began issuing new bank notes, like these ₹200 notes. They created the notes with some built-in anti-counterfeiting features. Bidyut Das, a PhD student at Cotton University in the lab of Abdul Wahab, usually uses the lab’s ultraviolet-light chamber to look at fluorescent dyes he’s studying for high-efficiency solar cells, but this time he chose to check out one of the notes’ security features: a variety of fluorescent dyes used to print images on the bill and its security ribbon. When he placed the bill under ultraviolet light (top), he could see designs and words not visible under normal light (bottom).
Submitted by Bidyut Das (fluorescing note); Credit: Shutterstock (visible-light note)
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