This Nikon Ti-U is an inverted widefield epifluorescence microscope with both fluorescence and color imaging (RGB, histology). For fluorescence, this microscope uses an Excelitas Excite 100-watt metal ...

You just moved the stage instead. This won't happen with Nikon's new Eclipse E600 microscope because its stage control is on the other side of the microscope from its coaxial course/fine focus control ...