Fluorescence microscopy requires which type of lamp?

• A. Tungsten lamp
• B. Mercury or Halogen lamp
• C. Xenon lamp
• D. LED lamp

Answer: (B)

Fluorescence microscopy relies on exciting fluorophores with light of specific, short wavelengths that match their excitation spectra. The illumination source must provide bright, stable light in the UV or blue region to reliably stimulate fluorescence. Mercury arc lamps are ideal for this because they emit strong UV and blue lines that efficiently excite many common fluorophores. Some older or particular setups also use halogen (tungsten-halogen) lamps, which deliver a broad visible spectrum with appropriate excitation filters to reach the needed wavelengths in certain configurations. Ordinary tungsten (non-halogen) halogen lamps generally don’t supply enough UV/blue light for robust fluorescence excitation. Xenon arc lamps are also used in fluorescence, and LEDs are widely used in modern systems, but the traditional and commonly tested pairing for excitation in many fluorescence setups is mercury arc lamps, with halogen lamps as a viable alternative in some configurations.