Microscopy and Microanalysis

Biological Applications

Light-Emitting Diodes Are Better Illumination Sources for Biological Microscopy than Conventional Sources

Richard W. Colea1 c1 and James N. Turnera1

a1 Wadsworth Center, New York State Department of Health, P.O. Box 509, Albany, NY 12201, USA

Abstract

Light-emitting diodes (LEDs) can be easily and inexpensively integrated into modern light microscopes. There are numerous advantages of LEDs as illumination sources; most notably, they provide brightness and spectral control. We demonstrate that for transmitted light imaging, an LED can replace the traditional tungsten filament bulb while offering longer life; no color temperature change with intensity change; reduced emission in the infrared region, which is important for live cell imaging; and reduced cost of ownership. We show a direct substitution of the typical tungsten bulb with a commercially available LED and demonstrated the color stability by imaging a histology section over a wide range of light intensities. For fluorescent imaging, where the typical illumination sources are mercury or xenon lamps, we demonstrate that LEDs offer advantages of providing a longer lifespan, having a more constant intensity output over time, more homogeneous illumination, and significantly lower photon dose. Our LED equipped system was used to image and deconvolve dual fluorescently labeled cells, as well as image cells undergoing mitosis expressing green fluorescent protein–histone 2B complex. The timing of the stages of mitosis is well established as an indicator of cell viability.

(Received October 26 2007)

(Accepted January 10 2008)

Correspondence:

c1 Corresponding author. E-mail: rcole@wadsworth.org