| 摘要 |
PROBLEM TO BE SOLVED: To restore the temperature control of a wavelength conversion element to a controllable state promptly when it has reached an uncontrollable state due to a high temperature hang-up state, and to restore high optical output.SOLUTION: Fundamental wave light emitted from a semiconductor laser 2 is converted in wavelength by a wavelength conversion element 5 to be emitted. A lightning circuit 20 supplies the semiconductor laser 2 with electric power to light the semiconductor laser 2. Temperature control means 21b controls the amount of electric power supply of a heater 7 so that the temperature of the wavelength conversion element 5 reaches a temperature at which its wavelength conversion efficiency becomes optimal. When a state where the amount of electric power supply of the heater 7 controlled by the temperature control means 21b is a predetermined lower limit or less continues for a predetermined period or longer, or when duration time in a state where the actually measured temperature of the wavelength conversion element is higher than the control target temperature of the wavelength conversion element becomes longer than a predetermined constant value, hang-up suppressing means 21c reduces a laser lighting current by a predetermined amount, and restoring from a high temperature hang-up state is performed. |
