| 摘要 |
PURPOSE:To always obtain a predetermined optical output of a laser diode even if an environmental temperature is varied by detecting the peak value of the optical output of the diode, applying it to pulse width varying means, simultaneously detecting the mean value of the optical outputs, and applying it to a laser diode driving circuit. CONSTITUTION:The peak value of the optical output obtained by a peak detector 70 is applied to one input terminal of an operational amplifier 80, a pulse width control voltage Vpcont is set to the other input terminal, and the differential voltage of both is input as a Vcomp to the base of a Tr32. On the other hand, the mean value of the optical outputs obtained by a mean value detector 71 is applied to one input terminal of an operational amplifier 81, a mean control voltage Vacont is set to the other input terminal, the differential voltage of both is input, as Vave, to the base of a Tr50, and the peak current of the optical output of the LD10 is controlled. Assume now that the environmental temperature is varied, for example, to a higher temperature side, an optical output having a narrow pulse width and a large peak value is obtained, and it is so controlled by the control voltage input to the Tr50 that the mean value of the optical outputs becomes constant, thereby obtaining a predetermined optical output pulse with the peak value pulse width. |
