3M has developed a proprietary laser process for creating three-dimensional images that appear to float above and/or below the plane of a substrate containing an array of microlenses. During the imaging process the laser records a microscopic image of the desired three-dimensional pattern in the material located at the focal point of each microlens in the array. The images exhibit motion parallax comparable to that seen from holograms and are easily visible in a wide range of ambient lighting conditions. The images are therefore similar, but not identical, to integral images, first proposed in 1908 by Lippmann. The fidelity of these floating images requires maintaining exact registration between the microlens array and the corresponding microimage array. In addition, the use of an ablative laser process for the production of the microimages enables the production of microimage features smaller than the diffraction limit (up to approximately 50,000 dpi). The images are therefore very difficult to simulate, counterfeit, or modify and are highly desirable as an overt security feature. 3M has scaled up the floating image process to produce images in ConfirmTM Retroreflective Security Laminate to authenticate passports and driver's licenses and in retroreflective license plate sheeting as the EnsureTM Virtual Security Thread to authenticate vehicle registration. This allows addition of features to a secure document that are easily verifiable, using only the human eye, by a large and widely disperse population to create an identity document that is easily identified as genuine.


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    Title :

    Three-dimensional floating images as overt security features



    Conference:

    Optical Security and Counterfeit Deterrence Techniques VI ; 2006 ; San Jose,California,United States


    Published in:

    Publication date :

    2006-02-08





    Type of media :

    Conference paper


    Type of material :

    Electronic Resource


    Language :

    English



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