| 摘要 |
PURPOSE:To prevent the production of noise, by changing the set temperature to a proper value so as to prevent the combination of the light amount of a laser beam emitted by a semiconductor laser and the temperature of the semiconductor laser from entering into a mode hopping noise producing region stored in a memory circuit. CONSTITUTION:A region where mode hopping noise is produced is specified by the combination of a light amount of a laser beam and a temperature of a semiconductor laser. Data of such region is recorded in a memory means 30. A control circuit 28 is supplied with data of the temperature of the semiconductor laser from a temperature sensor 22 and with data of the light amount of the laser beam from a light amount sensor 18. These temperature and light amount data are compared with the data of the mode hopping noise producing region supplied from the memory means 30. If the combination of the temperature and the light amount is going to enter the mode hopping noise producing region, the set temperature supplied to a temperature controller 26 is changed such that the temperature is controlled to prevent the production of mode hopping noise. |
