Photonics, electronics and related applications

In specifying a sensor/transducer , it is necessary to identify the input and output energy. As for example, 

Sometimes the transducers utilize an auxiliary source of energy as in some electrical device with electrical energy as input and output forms, but the output signal is determined by an auxiliary form such as thermal or radiation energy. The transducers need to be specified by input, output and auxiliary forms and in such a case, they are known as self-modulating transducers. When no auxiliary form of energy is involved one has selfregulating transducers. 

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