The Fluorescence Microscope
In fluorescence microscopy, wide variations between localized fluorophore concentrations within the specimen, coupled to differences in extinction coefficient and quantum yield from one fluorochrome to another, significantly influence the emission signal produced for a given quantity of excitation intensity. Considering that many specimens contain only minute quantities of fluorescent material in any particular viewfield, these combined factors produce an average level of fluorescence emission that is four to six orders of magnitude less than the excitation intensity.
Fluorescence microscopes have evolved with speed over the past decade, coupled to equally rapid advances in laser technology, solid-state detectors, interference thin film fabrication, and computer-based image analysis.
Discussed in this section are the various aspects of transmitted fluorescence illumination and equipment configurations needed to perform this type of microscopy.
Fluorescence Microscope Schematic Diagrams
The modern Olympus BX51 Upright epi-fluorescence microscope is equipped with a vertical illuminator that contains a turret of filter cubes and a mercury or xenon arc lamp housing.
Microscopes with an inverted-style frame are designed primarily for tissue culture applications and are capable of producing fluorescence illumination through an episcopic and optical pathway.
Interactive Java Tutorials
In reflected light Köhler illumination, an image of the light source is focused by the lens onto the aperture iris diaphragm located in the vertical illuminator as seen in this tutorial.
Explore illumination pathways in the Olympus BX51 research-level upright microscope. The microscope drawing presented in the tutorial illustrates a cut-away diagram of the Olympus BX51 microscope.
Explore light pathways through an inverted tissue culture microscope equipped with for both diascopic (tungsten-halogen) and epi-fluorescence (mercury arc) illumination in this interactive tutorial