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Security holograms are a vital anti-counterfeiting measure on banknotes, ID cards, and passports. A recent hologram fabrication method involving graphene oxide reduction explores new materials which can be used as holographic substrates. In this process, a graphene oxide layer is irradiated with a laser to produce reduced graphene oxide, or graphene. By controlling the path of the laser, the desired pattern is etched into the oxide layer. The etched regions act like a diffraction grating to produce a hologram.
However, holograms generated with this method cannot be rewritten in the event of mistakes. Wan et al. overcame this difficulty by performing an oxygen plasma treatment using Harrick Plasma’s Expanded Plasma Cleaner. Oxygen plasma reverses the graphene oxide reduction reaction, removing features previously etched by the laser. After plasma treatment, a new laser pattern was written into the material, creating a new hologram. This writing /plasma cleaning process was repeated several times before the hologram intensity decreased significantly.
Graphene Oxide Reduction Articles
[1] Wan, Z., Zhang, K., He, Y., Lin, D., Dong, H., Dong, Y., Zhang, Q., Fang, X., Chen, X., & Gu, M. (2023). “Graphene Lithography Based on Laser Reduction and Plasma Oxidization for Rewritable Hologram Imaging.” Advanced Optical Materials, (2022)11:202300872 doi.org/10.1002/adom.202300872
[2] Wan, Z., Zhang, K., He, Y., Lin, D., Dong, H., Dong, Y., Zhang, Q., Fang, X., Chen, X., & Gu, M. (2023). Supplemental Material for “Graphene Lithography Based on Laser Reduction and Plasma Oxidization for Rewritable Hologram Imaging” Advanced Optical Materials, (2022)11:202300872 doi.org/10.1002/adom.202300872