The present invention teaches an apparatus for consistent and accurate on-site readings of fluorescence signals of coronavirus test result, with which a user directly reads a fluorescent light qualitatively instead of using electronic sensors. The fluorescent light is excited from a fluorescent source in a site of interest in a target assay. The device comprises a light source for generating an excitation light for exciting the fluorescent source of the target assay to generate a fluorescent light, a component for accurately transmitting the excitation light and the fluorescent light with less noise or reflection, a component for consistent detecting of the fluorescent source by bare eyes with minimal health risks, and a user control system that requires minimal training.