Why holograms I hear you ask? Well...
Holograms are important in the prevention of forgery. Credit cards and banknotes have incorporated holograms as they are difficult to create and thus difficult to forge.
Physicists can use holograms to capture images of bubble chambers from which accurate measurements can be made
HOE (Holographic Optical Elements) are holograms made from a lens or a mirror. The hologram then takes on the properties of the optical element it was made from. HOE's are used to focus Laser beams, for example in barcode readers.
Intereferometry is the use of interference (see Explanations) to make tiny measurements, usually of angles or distances. An object is recorded hologramatically before and after it is subjected to a force. The change in the shape of the object due to the force is then recorded as an interference pattern of light and dark bands. This technique is used industrially as a method of quality control.