| 摘要 |
PURPOSE:To elongate the life of a crystal and stabilize the output of a laser beam, and improve the quality of a beam by providing an EO crystal in a constant-temperature vessel which has a laser beam transmitting window. CONSTITUTION:A constant-temperature vessel 10, which has an EO crystal 1 within and has a laser beam transmitting window 50a, is provided, and a heating coil 53 for heating the EO crystal 1 and a medium 51 is provided in the constant-temperature vessel 50. The EO crystal 1 is controlled for temperature within the constant-temperature vessel 50. The light damage of the EO crystal 1 can be reduced by keeping the stability of temperature not more than + or -5 deg.C, preferably, + or -1 deg.C, within the range of 50-250 deg.C, preferably, 150-200 deg.C in temperature of the medium 51, thus a laser beam 45 stable for a long term and excellent in beam quality can be gotten. In the condition that the temperature of this medium 51 is lower than 50 deg.C, the reduction of the light damage can not be achieved. Moreover, in the condition that the temperature is 250 deg.C, the occurrence of the impurities from the heating coil 53, etc., becomes active in the medium 51, it is necessary to control it to 250 deg.C or less. |
