LEDs for fluorescence microscopy

Traditional light sources for fluorescence microscopy have been mercury lamps, xenon lamps, and lasers. These sources have been essential in the development of fluorescence microscopy but each can have serious disadvantages: lack of near monochromaticity, heat generation, cost, lifetime of the light source, and possible distortions due to coherence effects. We are examining the possibility of using the new high-power light-emitting diode (LED) sources as alternatives to the above mentioned sources. LED sources are near monochromatic, are inexpensive, produce little heat, have no coherence problems, have extended lifetimes, are small, and can easily be modulated. We describe experiments comparing various LEDs to other light sources. We compare, for example, a 530 nm LED to the 546 nm line from a mercury lamp on a fluorophore whose absorption maximum is broad and in the middle between these two wavelengths.Quantitative Imaging GroupApplied Science