MEASURING AND MODELING THE FREQUENCY-RESPONSE OF INFRARED DETECTORS

It is shown that a light-emitting diode is a simple way of characteriz ing the frequency response of an infrared detector over several decade s of frequency, since the diode has a linear relationship between inpu t current and output radiant power. By normalizing a detector's output voltage to the diode input current, the detector frequency response c an be measured as simply as one measures the transfer function of an e lectrical filter. This is advantageous in studying higher-order effect s in a thermal-type detector response, where the detector deviates fro m the Lorentzian behavior predicted by a simple model of a lumped heat capacity connected to a thermal bath by a lumped thermal conductance path. An example is given of a thermoelectric detector with marked non -lorentzian behavior.