HOLOGRAM IMAGING TECHNIQUES AND HOLOGRAMS

摘要

This invention relates to improved techniques for reading holograms, in particular volume reflection holograms, and to improved security documents incorporating volume reflection holograms. A method of imaging a volume reflection hologram on a surface, said surface bearing said volume reflection hologram and printing, said hologram and said printing being at least partially co-incident, the method comprising: illuminating said surface at a first angle, said first angle being selected such that a first image stored in said volume reflection hologram is replayed; capturing a first image of said illuminated surface, said first image comprising an image of said printing and of said first stored image; illuminating said surface at a second angle, said second angle being selected such that substantially no image is replayed by said volume reflection hologram; capturing a second image of said illuminated surface, said second image comprising an image of said printing substantially without an image stored in said hologram; and generating an image of said first image stored in said hologram from said first captured image and said second captured image.