抄録
Turning an He-Ne ring laser (0.6328μm, triangular cavity, one or two D.C. discharge gain tubes) on a rotating table, the beat signal generated by the optical mixing of the clockwise and counter-clockwise laser beams has been observed. Simultaneously, the relation between the angular velocity and the beat frequency has been measured.
It is found that the frequency, waveform, and amplitude of the beat signal are extremely unstable in the region near the lock-in rate, and that the beat frequency has a linear relation to the angular velocity in the region far above the lock-in rate. The beat frequency from a ring laser with one gain tube has a bias from the expected value in the absence of mode-pulling effects by Langmuir flow. It is found that the magnitude of the bias increases monotonically with that of the discharge current in the region of 12-18mA, and to be about 1kHz at 18mA. The direction of the bias depends on that of the discharge current and on that of the ring laser rotation. The possibility of achieving zero bias frequency is experimentally shown using a ring laser with two gain tubes.
An improvement of the ring laser devices is suggested in consideration of the analysis made on the various causes of the noise in the beat signal. The conditions to operate a ring laser as a practical equipment for the precise measurement of the angular velocity are discussed.
