The aim of the paper is to study some factors influence on the contrast decreasing of the ampligram and phasegram obtained after optical lock-in thermography. It is analysed the effect of delay between excitation source modulated parameter changing and modulated signal due to thermal inertia of halogen lamp filament. Two software corrections for decreasing the effect of these factors are developed. In order to evaluate the effect of these corrections, lock-in thermography measurement is performed and multiple results processing at different correction parameters values are performed. The contrast dependence from correction parameters is presented in graphical form. Multiple results processing with random correction parameters values using the both corrections are performed for determination of maximum possible contrast An iterative method with less number of results processing for choosing appropriate values of correction parameters using the both corrections is proposed. The effect of this method is presented and compared in tabular and graphic form.
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