| 摘要 |
PURPOSE:To suppress the deterioration of oscillating characteristics accompanging the change in ambient temperature to a large extent and to improve reliability, by forming a pair of optical substrate, which support both reflecting mirrors, with Ni cast iron having a small thermal expansion coefficient. CONSTITUTION:In the Table, the thermal expansion coefficients of materials (a), which constitute a pair of optical substrate 6, are compared. Among the materials, the thermal expansion coefficient of Ni cast iron (b) has the smallest value. Above all, the thermal expansion coefficient of high Ni cast iron, which includes 30 wt % or more Ni, is about 1/3-1/4 those of gray cast iron (c) and steels for general structures. Therefore, each optical substrate is formed with the high Ni cast iron having the small thermal expansion coefficient. In a laser oscillator constituted in this way, the thermal expansion of the optical substrate 6 is very small even if ambient temperature of the optical substrate is changed by the output of laser beam. A resonator can be maintained stably. Thus, the deterioration in oscillating characteristics accompanying the change in ambient temperature is largely suppressed, and the highly reliable laser oscillator is obtained. |
