Micro-electromechanical apparatus and method with position sensor compensation to compensate for sensor drift. A preferred embodiment comprises modifying the intensity of a light source used in position detection to maintain a constant sum of the voltages output from photodetectors receiving light from the light source. Preferred embodiments may be implemented in digital signal processor code, or external to the processor in analog circuitry. By adjusting light source intensity, position calculations may be performed without normalization, and thus without a time-consuming division operation.