Abstract: A process for controlling the preconduction current of a laser diode that operates in conjunction with a monitor diode in a control circuit with operational amplifiers, comprising signal processing filters, an electric supply unit such as, e.g., a power source, and a zero crossing detector, where the laser diode (5a) is driven by a linear current ramp signal provided by the supply unit, that the output signal (16) of the monitor diode (15) is differentiated three times, and that, when a zero crossing of the triple-differentiated monitor diode output signal (16) is detected, an optimum current of the current ramp signal is retained by the action of the zero passage detector.