A Free Electron Laser (FEL) is a type of laser that generates high-intensity light by using free electrons. Unlike traditional lasers that rely on atoms or molecules, FELs use a beam of electrons accelerated to nearly the speed of light. These electrons pass through a magnetic structure, causing them to emit coherent light across a wide range of wavelengths, from infrared to X-rays. FELs are valuable in various fields, including medical imaging, materials science, and fundamental physics research. Their ability to produce tunable and intense light makes them useful for studying the properties of materials and biological systems at the molecular level.