ACTUATION AND EVALUATION CIRCUIT, MEASURING DEVICE AND METHOD FOR MEASURING THE CONCENTRATION OF A GAS

摘要

The invention relates to an actuation and evaluation circuit for a laser diode (1) and a photodiode (3) for determining the concentration of a gas. The laser diode, for example a variable frequency semi-conductor laser in the form of a DFB semi-conductor laser, can generate light in the range of an absorption line of the gas. The circuit comprises a driver (10, 11, 12, 13) for generating a driver signal (17) for the laser diode (1), an assembly (8, 9) for generating a reference signal (20), and a subtractor (5) for subtracting the reference signal (20) from the signal (21) supplied by the photodiode, in order to compensate the non-linear characteristic lines of the semi-conductor laser. The invention further relates to a measuring device for determining the concentration of a gas by way of such an actuation and evaluation circuit. Finally, the invention relates to a corresponding method.