Composite crystal colloidal array with photochromic member
The invention includes a composite material for use in a security device including a radiation diffracting component that exhibits a first optical effect and a photochromic component that exhibits a second optical effect. The composite material is particularly suited for use in authenticating articles, such as currency.
PPG Industries Ohio, Inc
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B42D B42D G02B B42D B42D B82Y G02B
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Wei Anil Xiangling Sean Jessica M. Noel R. Shan
Wang Kumar Xu Purdy Williamson Vanier Cheng