| 摘要 |
PURPOSE:To always grasp an operating state and to obtain information of maintenance whether it is normal deterioration or abnormality by comparing a monitoring output with one of a plurality of comparison reference values, and sequentially comparing it with other comparison reference value to detect the operating state. CONSTITUTION:It is applied to a semiconductor laser device having an APC circuit including a current limiter to detect a deterioration or an abnormality, for example, in two stages. A first comparison reference voltage V2 is set to a value lower than a monitoring voltage at normal time. When a laser diode 1 is deteriorated to reduce a monitoring voltage V0, the output of a comparator 24 is inverted. The deterioration or abnormality of first stage of the diode 1 is notified to an exterior. A second comparison reference voltage V3 is set to a value lower than the first voltage. When the deterioration of the diode 1 is advanced so that the voltage V0 is further reduced, the output of the comparator 30 is inverted. The deterioration or abnormality of second stage is notified. |
