| 摘要 |
PURPOSE:To enable a desired control to be performed for a controlled laser device as well which has a large modulation index and is modulated with an FSK, by a method wherein after only a low frequency component is selected from a beat signal, the envelope thereof is differentiated and then subjected to a half-wave rectification to form two pulses, and subsequently one pulse of the two pulses which are obtained in one of a plurality of laser devices is made a component of a beat pulse train. CONSTITUTION:From a double-humped beat pulse corresponding to an FSK modulated light, only the rear hump part is selected. Next, the resultant pulse is applied to a circuit a whose output is to be sent to a counter. In this connection, in the circuit (a), the pulse is differentiated through a differentiation circuit and subsequently converted into two pulses by a diode. Thereafter, these two pulses are shaped into two square waves each of which has the amplitude equal to a logical level through both a Schmitt trigger circuit and a NOT logic element. Further, the former pulse is eliminated through both a T.FF and an OR circuit in the next stage, but the latter pulse is inputted to a counter in the following next stage. Thus, by the operation of the circuit (a), the double-humped beat pulse corresponding to the spectrum of the RSK modulated light is converted into a single pulse which rises at the time corresponding to the center frequency of a modulated wave. As a result, the interval of an oscillation frequency can be stabilized for the FSK modulated light. |
