Rayf Shiell passionately balances both research and teaching at Trent University, Canada. His primary research is in optics and ranges from probing matter using high-power laser beams to exploring the optics of the eye. He teaches a wide range of courses and delights in uncovering the often surprising connections between them. His love of good pedagogy has permeated not only this present text, from which he has taught for many years, but all his work as a mentor and instructor, extending also to coaching the university rowing team. He is co-developer of the integrated testlet, an assessment tool that employs a scaffolded answer-until-correct question structure, which features in each chapter of this text. For this work he was a co-recipient of Trent University's 2021 Award for Educational Leadership and Innovation. Iain McNab is a former Dean of the Faculty of Applied Science and Technology at Sheridan College, Canada; he counts among his mentors Nobel Laureates Harold Kroto and John Polanyi. At Newcastle University, UK, he was Head of the physics teaching laboratories and led research in laser spectroscopy. He has taught widely in physics and engineering and was an early adopter of innovative methods such as the flipped classroom and web-based learning systems. Iain is a former Chair: Spectroscopy Group of the Institute of Physics and currently runs the McNab Group, teaches for Canadian Laser Safety, and is a visiting Professor at Guangdong Technion Israel Institute of Technology, China. Matthew Romerein earned his M.Sc. in Materials Science from Trent University, researching polarimetry and spectroscopy. Working closely with the authors, he endeavoured to improve the clarity, scientific accuracy and educational impact of the figures in this book. The accompanying interactive animations were also designed by Matthew, who develops quality assurance testing software for the RF industry.