In order to increase the anticounterfeiting performance of interference security image structures, we propose to implement an active component using an electrochromic material. This novel device, based on metamerism, offers the possibility of creating various surprising optical effects, it is more challenging to duplicate due to its complexity, and it adds a second level of authentication. By designing optical filters that match the bleached and colored states of the electrochromic device, one can obtain two hidden images—one appearing when the device is tilted, and the other one disappearing when the device is colored under an applied potential. Specifically, we present an example of a filter that is metameric with the colored state of the electrochromic device, demonstrate how the dynamic nature of the device offers more fabrication flexibility, and discuss its performance. We also describe a design methodology for metameric filters based on the luminous efficiency curve of the human eye: this approach results in filters with a lower number of layers and hence lower fabrication costs, and with a lower color difference sensitivity under various illuminants and for nonstandard observers.
© 2011 Optical Society of America
Original Manuscript: July 27, 2010
Revised Manuscript: September 7, 2010
Manuscript Accepted: September 10, 2010
Published: October 14, 2010
Bill Baloukas, Jean-Michel Lamarre, and Ludvik Martinu, "Active metameric security devices using an electrochromic material," Appl. Opt. 50, C41-C49 (2011)