Abstract: An apparatus for measuring multiple wavelengths of fluorescence emitted from fluorescent dye-treated cells, tissue preparations, or solutions which is comprised of a custom designed optical module into which is integrally fitted a source of long wavelength red light, a specimen stage, an epifluorescence system, a high intensity ultraviolet light source for excitation, an optical subassembly which permits simultaneous fluorescence detection and real time visualization of the subject under study. A standard microscope may be used in place of the custom designed optical module for integration of the component systems.