1. A method of controlling beam quality and stability of a laser apparatus, the laser apparatus comprising, a diode laser providing first radiation of at least a first wavelength, and a frequency conversion unit configured to frequency-convert the first radiation from the diode laser and to output the frequency-converted radiation, the frequency-converted radiation having at least a second wavelength different from the first wavelength, the diode laser comprising at least a first and a second section, a first contact for injecting a first current into the first section, a second contact for injecting a second current into the second section, and means for controlling a temperature of the diode laser; wherein the method comprises: monitoring a first parameter indicative of the power content of a dominant lobe of the first radiation; iteratively determining a combination of respective values of the first current, the second current and the temperature at which combination of respective values the monitored first parameter and a stability parameter indicative of a fluctuation over time of the monitored first parameter each fulfils a respective predetermined optimization criterion; and setting the first current, the second current, and the temperature to the determined combination of respective values.