A system for detecting fluorescence emitted from a plurality of samples in a sample tray is provided. The system generally includes a plurality of lenses positioned in a linear arrangement, a linear actuator configured to translate the plurality of lenses, an excitation light source for generating an excitation light, an excitation light direction mechanism for directing the excitation light to a single lens of the plurality of lenses at a time so that a single sample holder aligned with the lens is illuminated at a time, and an optical detection system for analyzing light from the sample holders. In certain embodiments, the optical detection system includes a light dispersing element configured to spectrally disperse the light from the sample holder being illuminated, and a lens element configured to receive light from the light dispersing element and direct the light onto a light detection device. A method of scanning a sample tray having a plurality of samples positioned in sample holders to detect fluorescence is also provided.