A system and method are used to convert a parallel datastream to a serial datastream. A laser control circuit compares a value of the light power signal with a predetermined value, adjusts a terminal voltage of a capacitor based on a result of the comparison, controls emission power of one of the light sources in accordance with the terminal voltage of the capacitor, and executes the control once for each light source during a plurality of scanning operations. These changes in material stress can affect the operation of the overall MEMS device.