The aim of this work is the estimation of the specimen thickness from pulsed thermography data using the virtual wave concept. A virtual wave signal is calculated by applying a local transformation to the measured temperature data. This virtual wave is a solution of the wave equation, whereby for the parameter estimation also ultrasonic evaluation methods can be used, e.g. pulse-echo method for time-of-flight measurements. The time-of-flight is directly related to the distance traveled by the wave and can be used to reconstruct the position of the interface. This method yields a very good estimation of the thickness of a steel step wedge, with the advantage that the same evaluation method can be used for reflection as well as transmission measurements.