Method in which, in order to actuate a wavelength-tunable laser diode in a spectrometer, a power-time function is predetermined instead of a current-time function, wherein the laser diode is tuned periodically over a wavelength range in accordance with the power-time function. For this purpose, a current profile (i) with which the laser diode is actuated is determined from the power-time function and measured values of the voltage (u) present at the laser diode.