| 摘要 |
PROBLEM TO BE SOLVED: To provide a raster output scanner for adjusting a beam intensity by using a low cost and comparatively slower velocity constitutional element. SOLUTION: A beam intensity detection and control network 300 is operated to dynamically maintain the intensity of a light from a laser diode at a specified value. When an output from the laser diode is below a specified level, that is, a voltage from a sample held circuit 314 is lower than a reference voltage 322, a digital value included in an up/down counter 326 is incrementally set to entail an increase in the reference current 336 and a consequent increase in the amplitude of a laser excitation current with the increased intensity of a laser beam. When the output from the laser diode is too large, that is, the voltage from the sample hold circuit 314 is higher than the reference voltage 322, the digital content stored in the up/down counter is decrementally set to decrease the reference current 336. Thus the laser excitation current is decreased and consequently, the intensity of the laser beam is decreased. |
