In this work we present a simple and illustrative arrangement using materials available in research and teaching laboratories to measure fluorescence. The developed fluorimeter is basically composed of a dual LED lighting to excite the samples and produce their emission. Then, a converging lens focuses the emitted light in the entrance of a monochromator and a chopper is used to modulate this signal with a known frequency measured by an optical coupler. After that, the light enters the monochromator that is responsible for its spectral decomposition into components that are finally detected by an amplified photodiode. Since the intensity of the emitted light is very low, a lock-in amplifier is used for filtering this signal by the reference signal provided by the optical coupler. This fluorimeter was tested using an acridine orange fluorescence sample and the results were very similar to those expected by a commercial fluorimeter.
fluorimeter; fluorescence; fluorescence measurement; fluorescence spectroscopy
