The Motic EF-UPR is an Epi-Fluorescence light system installed on a microscope to enable fluorescence microscopy.  This product easily connects to your BA410 microscope, and holds three filter cassettes for excitation observation.
 
Fluorescence is a unique observation method, enabled by an optical phenomenon - light is absorbed by a material, creating a molecular excitation that causes the material to re-emit light at a different wavelength.  The use of epi-illuminators in fluorescence microscopy is an adaption of the vertical illuminator used in reflected light observation.
 
The radiation emitted by the light source first passes through the exciting filter and is incident to a short- pass filter* (dichroic beam splitter). The radiation is then reflected into the objective, which also serves as a condenser.
 
The objective concentrates the exciting radiation in the object field. Fluorescent light emitted from there, is collected by the objective and returned in the opposite direction to the short-pass filter, which directs it into the eyepiece through the barrier filter.
 
 
*A filter designed to allow the passage of radiation of wavelengths shorter than a given limit.