Which instrument uses an electron gun to achieve high-resolution imaging?

• A. Light microscope
• B. Electron microscope
• C. Fluorescence microscope
• D. Light sheet microscope

Answer: (B)

Using an electron gun to generate a beam of electrons is what enables high-resolution imaging. Electrons have much shorter wavelengths than visible light when accelerated to high speeds, so they can resolve far finer details. An electron gun emits the electrons, which are then accelerated by a strong electric field and focused with magnetic lenses to form an image. In transmission electron microscopy, the beam passes through thin samples to reveal internal structures, while in scanning electron microscopy it scans the surface and detects emitted signals to build a surface image. Light-based instruments rely on photons, and their resolution is limited by the wavelength of light and optical diffraction, so they can’t reach the same nanometer-scale detail as electron-based systems.