| 摘要 |
PURPOSE:To enable to obtain a high performance detecting device by detecting a variation of the oscillated wave length following to a positional change of an outside mirror in an outside-resonator type semiconductor laser using a heterodyne formula. CONSTITUTION:An output of a semiconductor laser 11 is fed to an input terminal of a differential frequency detecting device 5 through an optical fiber 4. On the other hand, an output beam from an outside-resonator type semiconductor layer 8 is input to the other terminal of the device 5 through an optical fiber 5. And by detecting a differential frequency and transmitting through a lowpass filter 10, a variation of an oscillated frequency can be detected. As a result, a positional change of an outside mirror 12 can be detected. Meanwhile, the input current to a laser 6 is controlled by a return circuit 13 so that the differential frequency can be almost constant. And the detecting accuracy of this formula can be decided by a spectral bandwith of a laser and thus, a positional change can be detected in high accuracy.
|
