OPTICAL INFORMATION RECORDING AND REPRODUCING DEVICE

摘要

PURPOSE:To detect the linearity of quantum efficiency of a semiconductor laser by discriminating the presence or absence of deterioration of a light source from the drive current of the light source and the intensity of the optical output. CONSTITUTION:A photodetector 2 detects the light emitted from the rear side of a semiconductor laser 1 and delivers a reference signal corresponding to the reproduction mode through the 1st signal generating means 4. While a reference signal corresponding to the information record or erasion mode is delivered from the 2nd signal generating means 5. A control means 6 is controlled by the output signal of a comparator 3 which is compared with each reference signal. The control output of the means 6 is applied to the 1st drive means 7 in case a light source is driven by the weak output light and to the means 7 and then to the 2nd drive means 8 as a control signal when the light source is driven by the intensive output light respectively. At the same time, the input signal is supplied to the means 5 and the means 8 to change the light output of the light source and functions to control the light source to a desired level with high stability.