Atsushi Takeuchi (1960–) is a Japanese physicist and a professor at Waseda University’s Faculty of Science and Engineering. After studying engineering science at Osaka University and completing its graduate program, he worked at Fujitsu Laboratories and served as a visiting researcher at the Max Planck Institute for Solid State Research. Specializing in semiconductor physics and quantum electronics, he investigates ultrafast phenomena occurring on picosecond timescales in semiconductor quantum structures, as well as the optical generation and control of electron spins. He has also written numerous introductory books that explain physics and mathematics through high-school-level mathematics. “Koko sugaku de wakaru Furie henkan: Furie kyusu kara Rapurasu henkan made” develops the concepts of Fourier series and Fourier transforms—methods for representing complex waveforms as combinations of simpler waves—step by step from basic trigonometry and calculus.