Hitachi Industry and Control Solutions 1 article published in JoVE Engineering Gain-compensation Methodology for a Sinusoidal Scan of a Galvanometer Mirror in Proportional-Integral-Differential Control Using Pre-emphasis Techniques Tomohiko Hayakawa1, Takanoshin Watanabe2, Taku Senoo1, Masatoshi Ishikawa1 1Department of Creative Informatics, University of Tokyo, 2Hitachi Industry & Control Solutions, Ltd. We propose a method to extend the corresponding frequency by using a pre-emphasis technique. This method compensates for the gain reduction of a galvanometer mirror in sine-wave path tracking using proportional-integral-differential control.