Patent ID: 7643525

Claim:
A method of controlling a printhead comprising: providing a laser source; providing a plurality of current sources coupled to said laser source including at least a bias current source, a first drive current source and a second drive current source; defining a set of operating states where each operating state corresponds to a desired laser output power level set by driving said laser source using a corresponding combination of said plurality of current sources; setting a ratio that establishes a relationship between a first one of said desired laser output power levels and a second one of said desired laser output power levels; and performing a calibration operation by: sampling actual laser output power of said laser source for less than all of said operating states in said set; computing adjustments to the current levels of said plurality of current sources such that the current level of said second drive current source relates to the current level of said first drive current source based upon a function of said ratio and for each operating state that is sampled, the sampled laser power level converges towards a corresponding one of said desired laser output power levels associated with that sampled operating state; and adjusting said plurality of current sources including said bias current source, said first drive current source and said second drive current source to their corresponding computed current levels.