Reconstructing a hologram
An interference pattern can be considered an encoded version of a scene, requiring a particular key - the original light source - in order to view its contents. This missing key is provided later by shining a laser, identical to the one used to record the hologram, onto the developed film. When this beam illuminates the hologram, it is diffracted by the hologram's surface pattern. This produces a light field identical to the one originally produced by the scene and scattered onto the hologram
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