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Physical Origin of Noise

Noise is called fundamental when it arises from the particle nature of light and matter and can never be totally eliminated, while non-fundamental (or excess) noise is due to imperfect components and instrumentation and can at least theoretically be eliminated. Non-random noise is never fundamental.

Fundamental noise:

Non-fundamental noise:

Since an instrument consists of a lot of different components, which individually introduce noise into the signal, the resulting measurement is contaminated by noise which may show complex properties. Fortunately, either one component is dominant so that the other contributions can be neglected, or the central limit theorem applies. In the second case, the noise in the system shows normal distribution.

Last Update: 2002-Nov-03