Patent ID: 8692887

Claim:
An apparatus for determining variable thickness of a coating disposed on a substrate, the apparatus comprising: a flash-lamp source capable of generating a thermal pulse at the coating surface; an optical trigger coupled to the flash-lamp source and capable of initiating the flash-lamp firing; a transistor coupled to the flash lamp source and capable of quenching the thermal pulse; a reflective filter positioned between the flash-lamp source and the coating surface capable of preventing residual heat from the flash-lamp from heating the coating surface; an IR image capture device positioned to capture sequential image frames of the coating surface, where each sequential image frame corresponds to an elapsed time and comprises a pixel array, and wherein each pixel of the array corresponds to a location on the coating surface; a processor coupled to the IR image capture device, wherein the processor is programmed to: control the operation of the optical trigger and transistor; receive the image frames of the coating surface at the initiation of the flash-lamp firing and sequentially there after; and determine the thickness of the coating at selected points along the substrate using the sequential image frames to calculate a logarithmic time-temperature response curve for each pixel in the array corresponding to each of the selected points, to calculate an inflection point time for each logarithmic time-temperature response curve, wherein a time of maximum slope on the time-temperature response curve is defined as the inflection point time, and to select a temperature response for each pixel in the array corresponding to each of the selected points only at its corresponding inflection point time.