For industrial applications it is necessary that the test systems are portable, for example measuring the concentration of pollutants in water or characterization of processes that occur in plants or other organisms be developed in situ and in vivo. The need to make the system portable, leads us to develop a driver that automatically controls the intensity of power and modulation of the laser, measuring the temperature of the respective material to be analyzed. Presents the implementation of

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... characteristics of a field effect transistor metal-oxide-semiconductor as a tool for modulating the laser diode. The result is a driver and cost effective that can be used in various photothermal phenomena.