The importance and application of epifluorescence microscope in the study of hardened concrete in Switzerland and was then utilized chiefly as a device to identify the value of the air-void system in hardened concrete. The researchers utilized the ultraviolet light diffused through a thin section. The plan of the polarizing epifluorescence microscope creates probability to observe every point on a thin section with the entire light modes of a petrographic microscope alongside with incident ultraviolet light, and is therefore simply pliable to this purpose. The whole means of observing that are probable with a petrographic microscope were united with the capability to observe the fluorescence once lighted by means of ultraviolet light inside a thin section saturated with specifically dyed epoxy. The plan is such that altering the exciter filters through regulating turret housing and the dichroic mirrors by turning a slide across a slot, replacing barrier filters, and turning over the shutters are all that are needed to switch from one mode to the other mode. A scientist in the person of Soeder utilized epifluorescence microscope with a varied dye, dichroic mirrors and barrier filters to investigate the pore composition of rocks of low porosity.

It was discovered that when ultraviolet lighting was diffused through the thin section, it initiated fluorescence of the entire fluorescent dye throughout the thickness of the area. The dye was scattered all through the capillary pores, in the entire fissures no matter how diminutive, and in the whole minute hollows left behind in the paste as the cement hydrated. The fluorescence subsisted throughout the thickness of the area and formed a haze of uncollimated light that perplexed the entire observation with a cloud in which every opaque substance like cement ferrites appeared to float. If the area was over twenty five micrometer in thickness, even several of the air voids would be hard to identify from the surrounding haze.

The episode composition of the ultraviolet lighting required the utilization of the exposed thin sections and the kind of objective lenses needed by the exposed thin portions. The illumination produced inside the sample by the fluorescence of the dye is uncollimated and emits from all fluorescent point. Such uncollimated illumination hits a coated glass at arbitrary angles. Only illumination that hits a cover slip at ninety degrees to the surface will pass through directly. The illumination generated at other angles rebounds on all sides beneath the cover slip and from the highly completed surface of the thin section and produces a yellow haze that shrouds observation at everything but the lowest magnifications. For the reason that the incident ultraviolet illumination is collimated through the objective lens, there is a higher concentration of this illumination at the point of target with the superior power lenses such as extra ultraviolet illumination reaches every fluorescent molecule of the dye when the bigger power objectives are utilized. Hence, the fluorescence is more brilliant when the advanced power objectives are utilized. At extremely high magnifications such as sixty times objective of the epifluorescence microscope, the lens and lens mounting are so near to the sample that a yellow haze is created by illumination rebounded from the lens surface to the sample surface and back, just as when a cover slip is utilized.  Read more on this subject