  The rise of interest in the study of quantum emitters has recently prompted
many research groups to construct their own confocal epifluorescence
microscopy/spectroscopy instruments. The low light levels typically involved in
quantum emitter measurements makes it critically important to account for any
potential sources of background fluorescence by components used within such
setups. In this report, we show that emission originating from various
microscope objectives can possess elusive sharp linewidths that could
potentially be mistaken for quantum emission. Impurities present in many
glasses overlap in wavelength with single photon emission from several
candidate emitter systems of current interest. A careful consideration of this
system noise could be critical to exploratory work of the optical properties of
materials such as transition metal dichalcogenides and hexagonal boron nitride.
