| 摘要 |
PURPOSE:To stabilize the frequency of the title laser by preventing inversion of polarization by impressing a specific static magnetic field upon the inside of the laser thin tube and, at the same time, feedback-controlling the resonator length by utilizing a beat output produced at the time of three-longitudinal mode oscillation when the longitudinal mode having an inherent polarizing direction is positioned in a specific state after performing frequency-voltage conversion on the beat output after detection. CONSTITUTION:The light leaking out from the rear mirror of a laser tube LA is detected by means of a photodiode PD through a linearly polarizing plate LP1 and the signal of the diode PD is converted into a change in voltage by means of a frequency-voltage converter FV after passing through a band-pass filter BPF. That is, a change in the beat frequency is converted into a change in voltage as shown in the figure. The electric power supplied to a heater HE is controlled by utilizing the voltage change as an error signal and, as a result, the resonator length of the laser tube LA is fixed. Therefore, the frequency of the laser is stabilized to a fixed value. |
