| 摘要 |
PURPOSE:To enable the detection of fine vibration by detecting the cycle of the frequency variation of a beat signal obtained after a heterodyne detection of output lights of a first laser, and a second laser having its oscillation frequency being stabilized precisely. CONSTITUTION:A back incident light 2 of a first laser 1 for detection of vibration is reflected with an external reflector 4 integrated with a displacement detector section 5 and fed back to the laser 1. On the other hand, the output light 7 of a second laser 6 is separated into a control signal light 9 and a reference light 10 with a beam splitter 8. The control signal light 9 is received with a photo detector 12 after passing through a wavelength discriminating element 11 and fed back to the second laser 6 as a control signal 14 after passing through a control circuit 13. A forward incident light 3 of the first laser 1 and the reference light 10 are synthesized with a light synthesizer 15 and heterodyne detected with a photo detector 16. The best signal 17 thus obtained is converted into an electronic signal 19 having the vibration and cycle corresponding to the oscillation detected by a frequency discriminator 18. |
