Fluorescence microscopy uses a much higher intensity light to illuminate the sample. This light excites fluorescence species in the sample, which then emit light of a longer wavelength. The image produced is based on the second light source or the emission wavelength of the fluorescent species -- rather than from the light originally used to illuminate, and excite, the sample.
Specifically, a dichroic mirror is used to separate the excitation and emission light paths. Within the objective, the excitation/emission share the same optics. In a fluorescence microscope, the dichroic mirror separates the light paths.
|Panel A) Anaphase Image and B) Telophase Image both labeled with centromeric probes for chromosomes 17 (green) and 12 (red).|
|Cells stained for cytosolic and nuclear proteins with a DAPI counterstain|