NEW SEQUENTIAL METHOD TO PROCESS NOISY TEMPERATURE RESPONSE FROM FLASH EXPERIMENT MEASURED BY INFRARED CAMERA

The estimation of a thermal diffusivity map of a surface can be perfor med with an infrared camera by processing thermal images in response t o a pulse of radiant energy. Indirectly, it is then possible to map ot her properties (humidity, density, etc.). One of the first requirement s of this kind of device is to take into account the thermal measureme nt noise. When the thermal diffusivity varies by a small amount around a nominal value, a new method of sequential estimation based on an as ymptotic expansion is proposed. The confidence interval of this method has been analytically compared with success, to the moment method and the method of logarithmic transformation. An experiment demonstrated that thickness variations of 50 mu m can be detected on a plate 5 mm t hick for a sample of polyvinyl chloride. (C) 1998 American Institute o f Physics. [S0034-6748(98)02003-6].