Commonly, Fluorescence microscopes used in research applications are based on a set of optical filters:
- an excitation filter,
- a dichroic beam splitter, and
- an emission filter.
The excitation filter selects the wavelengths to excite a particular dye within the specimen, the emission filter serves as a kind of quality control by letting only the wavelengths of interest emitted by the fluorophore pass through. The dichroic mirror's purpose is to reflect light in the excitation band and transmit light in the emission band, enabling the classic epifluorescence incident light illumination.
Leica Microsystems’ fluorescence stereo microscopes use TripleBeam technology, a separate (third) beam path for fluorescence illumination of the sample without a dichroic mirror.
Therefore, one excitation filter for the illumination beam path and two emission filters, one for each observation beam path, are needed.
To obtain high quality fluorescence images, it is necessary to use an appropriate