Closure
The present module is a short introduction to optical methods that rely on photon-particle interaction and scattering for signal generation. Signals can be generated
- when the particle is large enough to cast a shadow,
- particle influences the wave-like parameters of light, frequency and phase, for example, or
- when the electrons are pumped to one of the (quantized) higher energy levels.
Correspondingly, signal strengths can be strong, mild, or very weak. The measurement costs are, in general, inversely proportional to the signal strength.
The connection between the signal intensity and the property to be measured has not been discussed in this chapter. The subject is quite vast and the reader is advised to consult the specialist literature on subject.
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