Security holograms

A modular master hologram stack comprising:

• a holder configured for interchangeable support of at least two multichannel image generation devices,
• a reservoir to contain refractive index matching fluid between said multichannel image generation devices,
• a support for at least one three-dimensional (3D) object or hologram of a 3D object beneath said multichannel image generation devices;
• wherein the modular master hologram stack is configured to record a holographic image onto holographic recording film, said holographic image comprising a hologram of a 3D object in conjunction with a multi-channel holographic image, the method comprising:
• forming a holographic recording stack by:
• positioning said holographic recording film over said multichannel image generation device;
• positioning said at least one 3D object or hologram of a 3D object under said multichannel image generation device;
• and
• providing a transparent window in said multichannel image generation device in a region above said at least one object;
• and then
• recording said holographic image in said holographic recording film by illuminating said stack through said holographic recording film with a laser light of at least one wavelength.