METHOD OF CONTROLLING AN OPTICAL OUTPUT POWER OF A LASER DIODE, CONTROL DEVICE AND SYSTEM

摘要

The present invention relates to the field of optical particle sensing and in particular to a method of controlling an optical output power of a laser diode (10). A method of controlling an optical output power of a laser diode (10) is presented, wherein the laser diode is associated with a photodiode (20), wherein the photodiode converts light received from the laser diode into an electrical photodiode current; the method comprising the steps of: obtaining first optical trimming parameters indicative of a first optical output power of the laser diode (10) at a first laser diode current and a second optical output power of the laser diode at a second laser diode current different from the first laser diode current, above lasing threshold under predetermined calibration conditions; obtaining second electrical trimming parameters indicative of a photodiode characteristic curve of photodiode current versus laser diode current under the predetermined calibration conditions; measuring a first photodiode current at a third laser diode current below lasing threshold; measuring a second photodiode current at a fourth laser diode current different from the third laser diode current below lasing threshold; determining a slope of a photodiode current versus laser diode current based on said measurement of the first photodiode current and said second photodiode current below lasing threshold; controlling the optical output power of the laser diode (10) above lasing threshold based on the first optical trimming parameters, the second electrical trimming parameters and the slope of the photodiode current versus laser diode current below lasing threshold.