How holograms works?

Though holography is often referred to as 3D photography, this is a misconception. A better analogy is sound recording where the sound field is encoded in such a way that it can later be reproduced. In holography, some of the light scattered from an object or a set of objects falls in the recording medium. A second light beam, known as the reference beam, also illuminates the recording medium, so that interference
occurs between the two beams.

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