Instrumentation for Fluorescence Measurement:

All fluorescence instruments use fundamentally the similar components as are used in absorption spectrophotometers. Thus, the geometric arrangement of the components is somewhat different. This is because of the purpose that any transmitted radiation is not measured along with the fluorescence. You know that the absorption and transmission of radiant energy occur only along the direction of the incident light while the fluorescence radiation emanates in all directions. Here the detection of transmitted radiation is prevented through placing the detector at a right angle to the transmitted beam.