Basic temperature correction of QWIP cameras in thermoelastic/plastic tests of composite materials

The present work is concerned with the use of a quantum well infrared photodetector (QWIP) infrared camera to measure very small temperature variations, which are related to thermoelastic/plastic effects, developing on composites under relatively low loads, either periodic or due to impact. As is evident from previous work, some temperature variations are difficult to measure, being at the edge of the IR camera resolution and/or affected by the instrument noise. Conversely, they may be valuable to get either information about the material characteristics and its behavior under periodic load (thermoelastic), or to assess the overall extension of delaminations due to impact (thermo-plastic). An image post-processing procedure is herein described that, with the help of a reference signal, allows for suppression of the instrument noise and better discrimination of thermal signatures induced by the two different loads.