Which illumination source is typically used with a fluorescence microscope?

• A. Halogen lamp
• B. Sodium lamp
• C. Xenon lamp
• D. LED only

Answer: (A)

Fluorescence microscopy relies on exciting fluorophores with bright, controllable light in the UV/blue range. A halogen lamp, while providing broadband visible light, delivers little UV and generates significant heat, making it inefficient for exciting many fluorophores. A sodium lamp emits nearly a single wavelength (589 nm) and lacks the broad excitation spectrum needed for multiple fluorophores. A xenon lamp, on the other hand, provides intense, broad-spectrum emission that covers UV and blue regions, offering versatile excitation for a wide range of fluorophores with stable output. LEDs are also used in modern systems, but claiming “LED only” doesn’t reflect setups that still rely on other excitation options or multi-wavelength configurations. Therefore, the xenon lamp is the typical choice among these options.