US 12,015,240 B2
Laser device and method of determining a malfunction of a laser diode
Philipp Henning Gerlach, Ulm (DE); Susanne Weidenfeld, Weilheim (DE); Robert Wolf, Dresden (DE); and Soren Sofke, Tuebingen (DE)
Assigned to TRUMPF PHOTONIC COMPONENTS GMBH, Ulm (DE)
Filed by TRUMPF Photonic Components GmbH, Ulm (DE); and Robert Bosch GmbH, Stuttgart (DE)
Filed on May 6, 2021, as Appl. No. 17/313,014.
Application 17/313,014 is a continuation of application No. PCT/EP2019/080642, filed on Nov. 8, 2019.
Claims priority of application No. 18205097 (EP), filed on Nov. 8, 2018.
Prior Publication US 2021/0273399 A1, Sep. 2, 2021
Int. Cl. G01J 1/42 (2006.01); H01S 5/00 (2006.01); H01S 5/026 (2006.01); H01S 5/183 (2006.01)
CPC H01S 5/0021 (2013.01) [G01J 1/4257 (2013.01); H01S 5/0264 (2013.01); H01S 5/183 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A laser device, comprising
a laser diode configured to emit radiation, wherein an output power of the radiation is dependent on a laser diode driving current;
a photodiode configured to receive the radiation emitted by the laser diode, wherein a photodiode current induced in the photodiode by the received radiation is dependent on a power of the received radiations; and
circuitry configured to:
measure first photodiode current values for at least two first laser diode driving current values at which the laser diode is in a non-lasing operation,
calculate a first linear slope from the measured first photodiode current values,
measure second photodiode current values for at least two second laser diode driving current values at which the laser diode is in a lasing operation,
calculate a second linear slope from the measured second photodiode current values,
determine a calculated laser threshold current of the at least one laser diode as the laser diode driving current value at which the first and second linear slopes intersect,
determine a ratio of the gradient of the second linear slope to the gradient of the first linear slope, and
detect a malfunction or degradation of the laser diode when the ratio is equal to or lower than a threshold.