An apparatus is provided that includes a light-emitting component, a light-detecting component, a lock-in amplifier, a frequency generator that is operatively linked to the lock-in amplifier and the light-emitting component, a speaker capable of emitting an audio signal wherein the output audio signal varies depending on the detected fluorescence in the sample, and a visible output of relative fluorescent intensity where the visible output varies depending on the detected fluorescence in the sample. The apparatus may also include a laser that is operatively coupled to the lock-in amplifier through a control switch, and focusing lens or an additional type of filter such as an interference filter, a short-pass filter, a notch filter, a long-pass filter or an infrared filter. The apparatus may be used to identify and/or to remove fluorescent or non-fluorescent material from a sample. Associated methods are also disclosed.
