| 摘要 |
PURPOSE:To output a predetermined optical output from an LD(laser diode) with respect to temperature change. CONSTITUTION:A TR(transistor) 2 is connected in series with an LD 1, and a forward current of the LD 1 is controlled by the TR 2. A parallel connection of a variable resistor 3, an FET 4 and a variable resistor 5 is connected in parallel with the LD 1 and the TR 2. A connecting point of the resistor 3 and the FET 4 is connected to a base of the TR 2. A constant current circuit is formed of the FET 4 and the resistor 5. A circuit current corresponding to a temperature change of a base voltage of the TR 2 is set by the resistor 5, an output current of the TR 2 is regulated to maintain an optical output of the LD 1 constant. |
