| 摘要 |
PURPOSE:To perform the automatic frequency control (AFC) of laser beam precisely and quickly by a method wherein a heterodyne detection is performed on the controlling laser beams, one of a plurality of spectrums is used as an objective substance and said spectrum is passed through the circuit containing a discriminator. CONSTITUTION:The heterodyne detection is performed on the control laser beams and an intermediate frequency signal is induced in filters FL1-FL3 from the input terminal 5 on a controlling device 10 through the intermediary of a distributor 7. The output of the filters FL1 and FL2 is rectified by detectors D1 and D2, and are compared by a comparator 11. On the other hand, the output of the filter FL3 is induced in a detector D3 and a discriminator 15 through the intermediary of distributor 14. The output of the detector D3 is compared with a reference voltage VS by a comparator 12. These outputs are induced in an output terminal 8 through the intermediary of electronic switches SW1 and SW2. |
