Holographic pigments

Figure 7-19 SEM photo of a holographic film made by aluminum metal deposition on a polymer film to be used for the production of holographic pigments. The average distance between the peaks of the structure is about 800 nm.

Holographic flake pigments are useful for the preparation of decorative coatings that can be used to emphasize the lines and contours of a three-dimensional surface. Another possibility is the application in molded plastics to provide a decorative appearance, e.g., in tiles. 

Nowadays most colorants have the purpose to satisfy our aesthetical needs and, thus, thousands of dyes and pigments are produced on industrial scales. Nevertheless, nearly periodically new demands arise for so-called fimctional dyes whose tt-conjugated systems exhibit novel functionahties beyond aesthetical purposes. Optical brighteners or near-infrared absorbers are examples where even transparency in the visible spectrum is desired and dyes for nonlinear optics, holographic optical data storage and two photon absorption are further examples where the color properties of dyes are insignificantly related to the functional demands. 

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