Patent ID: 6933475

Claim:
A method for turning on an optical radiation source, said optical source having associated therewith control circuitry to control the temperature of said optical source, the method comprising: pre-heating said optical source before said optical source is caused to emit optical radiation by heating said optical source to an initial temperature using heater and subsequently heating said optical source by causing a current to flow through said optical source, wherein said initial temperature is a function of at least one parameter selected from the group consisting of a minimum current value, a temperature to be reached by said optical source during operation, and an estimation of the intensity of the current flowing through said optical source in emitting said radiation during operation; the method including controlling the temperature of said optical source during said pre-heating as a function of a target temperature, wherein optical radiation is emitted as a result of current flowing through said optical source above a threshold value, and wherein said optical source has associated therewith control circuitry to control the current flowing through said optical source, and wherein pre-heating said optical source includes causing current to flow through said optical source with an intensity at least partly below said threshold value, whereby said optical source is pre-heated while still emitting negligible optical power.