| 摘要 |
PURPOSE:To decrease the fluctuation in a scanning spot diameter occurring in the deformation arising from a temp. change of a rotary polyhedral mirror by providing the functions to control scanning light intensity in such a manner that the approximately constant scanning spot diameter is obtd. regardless of the temp. of a rotary polyhedral mirror according to an adjustment signal to a scanning light intensity adjusting means. CONSTITUTION:The temp. of the rotary polyhedral mirror is detected by a temp. sensor 22 and is converted by an A/D converter 24 to a digital signal which is sent to a ROM 26. The output value corresponding to the temp. of the rotary polyhedral mirror 3 detected by the temp. sensor 22 is previously stored in the ROM 26 and the output value corresponding to the inputted temp. value is outputted therefrom and is inputted to a D/A converter 28. The D/A converter 28 modulates voltage according to the inputted value and outputs an output voltage and outputs an output voltage Vref. The scanning light intensity adjusting means automatically adjusts the light emission intensity of a semiconductor laser 32 in accordance with the adjustment signal so that the approximately the same scanning spot diameter is obtd. The diameter of the scanning spot is maintained approximately the same regardless of the temp. of the rotary polyhedral mirror and the good optical scanning is executed. |
