A high precision controller used to accurately drive low inertia galvanometer scanners is presented. Drift errors introduced by the galvanometer position sensor and its electronic driving circuit are compensated using two synchronization photodiodes or phototransistors. The effect of the temperature is analyzed, and comparisons are made with the conventional method of using an analog-to-digital converter to read the signal directly from the position sensor. Absolute accuracy of 10-5 is measured for a change of 10°C. This accuracy is limited to 10-2 when the galvanometer position sensor is used directly. Nonlinearity variations are negligible.