real-time transmitted realistic images that appear solid to the viewer and that the viewer can interact with.

Zero order device

often abbreviated to ZOD, these devices comprise gratings less than the wavelength of visible light (below 400 nanometres). These devices can be produced by embossing and display unique colour effects which are dependent on the plane of rotation of the device.

Volume hologram

otherwise known as a Bragg diffraction hologram, is where the thickness of the recording material is much larger than the wavelength of the light used for recording. The advantage of volume over surface relief holograms is the gain in image quality.