| 摘要 |
PURPOSE:To extend a dynamic range of laser rays of a semiconductor laser by a mehtod wherein the 1st semiconductor having a high optical output of a linear part of an optical output characteristic and the 2nd semiconductor having a low optical output are jointly used and a driving circuit of each laser can be changed over. CONSTITUTION:As for the 1st and 2nd semiconductor lasers 7, 8, the maximum and the minimum of a recording linear part of one semiconductor laser are respectively lower than the maximum and the minimum of the other. (or higher than the maximum and the minimum of the other). When an input signal S is smaller than a reference voltage Vo, it is entered into a driving circuit 6, and when it is larger than the reference voltage Vo, it is entered into a driving circuit 5 and a current having a linear relation to the magnitude of the input signal S is generated, respectively. As an entire light source device, the dynamic range of optical output is extended, thus, extinction ratio increases and a half tone recording is made possible. |
