NanoCODES: Nanofabrication of Cellular Optical Device Encryption Surfaces
Dr Robert Lee
Document Security Microtechnology, CSIRO Manufacturing & Infrastructure Technology
3.30pm, Friday 6 August 2004, AR103 Seminar Room, Graduate Research Centre
This talk describes a new approach to the design of optically variable devices for anti-counterfeiting
applications. Using arrays of micro-mirror pixels of very small size instead of arrays of miniature diffraction gratings we show
how the embossed hot stamping foil transfer step may be replaced by a much simpler transfer process involving only the use of
reflective nanophase inks and an embossed printing process. This simpler step provides a means for reducing the OVD replication
costs as well as providing for a more integrated process in producing the security document and is a result of the greatly increased
microstructure depth characteristics of the NanoCODES structures.
The optical physics associated with NanoCODES is analysed and it is demonstrated that the reflective
pixel ray equations are in isomorphic correspondence with the ray equations associated with diffractive devices. This mathematical
analysis shows how the optical effects generated by diffractive devices can be mapped into a corresponding set of reflective optical
effects. With the exception of colour effects all other characteristics of a diffractive OVD carry over into the reflective case.
The origination process for NanoCODES devices is also discussed, and while more complex than the process
used for diffractive devices (because of the extra photolithography step) the test results confirm the viability of the process.
Finally the application of the technology to the design of generic classes of micro mirror OVD devices
tuned to end user data encoding for ID applications is also discussed in the context of the rapid growth in ID fraud at the present
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