Patent ID: 7660336

Claim:
A method for determining a laser threshold of a laser diode, which is operated by a drive circuit as a function of a first signal in a first feedback and a second signal in a second feedback, the method comprising the steps of: supplying the first feedback via an optical coupling of an optical output signal of the laser diode; supplying the second feedback by an electrical signal picked up between the drive circuit and the laser diode independent of the optical coupling; comparing the electrical signal with an adjustable activation threshold; transmitting only a portion of the electrical signal that exceeds an adjustable activation threshold to the drive circuit in such a way that the second feedback is active only when the portion occurs; changing the adjustable activation threshold so that an activity state of the second feedback changes; and determining the laser threshold of the laser diode as a function of a value of the adjustable activation threshold during a change in the activity state of the second feedback, wherein the first feedback is derived from an output of said drive circuit and the second feedback is also derived from said output of said drive circuit.