What are the light sources used in Fluorophore microscope?
The light sources used on a fluorescence microscope are designed to provide intense light at specific excitation wavelengths to cause fluorophores in the specimen to fluoresce (emit light).
Arc Lamps
These are roadband light sources that emit light across the UV, visible, and sometimes near-infrared spectrum. Filters are used with these lamps to select the specific narrow wavelength band needed to excite a particular fluorophore.
- Mercury Arc Lamps (HBO): Produce high-intensity light with characteristic strong spectral peaks, particularly in the near-ultraviolet, violet, blue, and green regions. They are very bright, but the illumination across the field of view can be non-uniform.
- Xenon Arc Lamps: Provide a smoother, more continuous spectral output across the visible range than mercury lamps. They are often preferred for quantitative measurements where uniform intensity is critical, though they are typically less powerful at some key excitation peaks.
- Metal Halide Lamps: Offer a spectrum similar to mercury lamps but are more stable over time, which is an advantage for quantitative imaging, and have a longer lifespan.
Light-Emitting Diodes (LEDs)
LEDs are popular due to their long lifespan, low heat generation, and ability to be quickly and precisely controlled (on/off switching).
- Individual LEDs: Each LED generally emits light within a relatively narrow wavelength band. (20-70nm). Require no warm-up or cool-down time, and allow for rapid switching between wavelengths.
Lasers
Lasers are highly monochromatic (emitting light at a very narrow range of wavelengths), making them ideal for high-resolution and specialized imaging techniques.
- Types: Common lasers include Argon-ion (e.g., 488 nm), Helium-Neon (e.g., 543 nm, 633 nm), and various diode lasers (e.g., 405 nm).
- Applications: They are the primary light source for advanced techniques like Confocal Microscopy, Total Internal Reflection Fluorescence (TIRF) Microscopy, and Super-Resolution Microscopy (e.g., STED, PALM).
