Date of download: 7/6/2016 Copyright © 2016 SPIE. All rights reserved. Natural logarithmic plot of the surface temperature versus time (in milliseconds) for an infinitely thick stainless steel sample and a 4- mm thick slab. Figure Legend: From: Automated processing of thermographic derivatives for quality assurance Opt. Eng. 2007;46(5): doi: /

Date of download: 7/6/2016 Copyright © 2016 SPIE. All rights reserved. (a) Logarithmic plot for the 4-mm thick stainless steel slab, and its (b) first and (c) second derivatives, calculated with respect to ln(t). Figure Legend: From: Automated processing of thermographic derivatives for quality assurance Opt. Eng. 2007;46(5): doi: /

Date of download: 7/6/2016 Copyright © 2016 SPIE. All rights reserved. Invariance of the second logarithmic derivative, calculated from the series solution [Eq. ]. (a) Derivatives for 1-cm thick plates of stainless steel, steel, titanium, and copper are identical except for the time at which the peak occurs. (b) Derivatives for stainless steel plates of various thicknesses are identical except for their peak times. Figure Legend: From: Automated processing of thermographic derivatives for quality assurance Opt. Eng. 2007;46(5): doi: /

Date of download: 7/6/2016 Copyright © 2016 SPIE. All rights reserved. Comparison of the logarithmic second derivative of the surface temperature (a) and the temperature of the back wall (b). The back wall reaches 91% of its maximum temperature at the time of the second derivative peak. Figure Legend: From: Automated processing of thermographic derivatives for quality assurance Opt. Eng. 2007;46(5): doi: /

Date of download: 7/6/2016 Copyright © 2016 SPIE. All rights reserved. (a) Logarithmic plot of experimental surface temperature data and fit function acquired from integration of the Gaussian for a 0.25-in. thick stainless steel plate. The R2 value for the fit is (b) Comparison of the second derivative acquired from the fit with the derivative for the ideal adiabatic slab. Figure Legend: From: Automated processing of thermographic derivatives for quality assurance Opt. Eng. 2007;46(5): doi: /

Date of download: 7/6/2016 Copyright © 2016 SPIE. All rights reserved. (a) Sketch of graphite epoxy sample with steps and film inserts. (b) Raw IR image of the sample acquired 6s after flash heating. Figure Legend: From: Automated processing of thermographic derivatives for quality assurance Opt. Eng. 2007;46(5): doi: /

Date of download: 7/6/2016 Copyright © 2016 SPIE. All rights reserved. Binary map based on second derivative amplitude and time behavior shows potential defects as black and defect-free areas as white. Figure Legend: From: Automated processing of thermographic derivatives for quality assurance Opt. Eng. 2007;46(5): doi: /

Date of download: 7/6/2016 Copyright © 2016 SPIE. All rights reserved. Typical defect-free second derivative peaks in the composite sample fall in a finite time and amplitude range (red box). Signals that fall outside that range are potential defects. (Color online only.) Figure Legend: From: Automated processing of thermographic derivatives for quality assurance Opt. Eng. 2007;46(5): doi: /