Method and system for the examination of a sample by means of thermography

The invention provides a method for a non-destructive, non-contacting and image forming examination of a sample by means of heat flow thermography. The method comprises exciting the sample at least twice independently from each other by means of the heat pulses from the excitation source; taking a first thermal image of the surface of the sample at a first time distance Δt1 from a first triggering of the heat pulse which first time distance Δt1 is characteristic for gradients in heat flow velocity in a first depth below the surface of the sample; taking a second thermal image of the surface of the sample at a 1 second time distance Δt2 from a second triggering of the heat pulse which second time distance Δt2 is characteristic for gradients in heat flow velocity in a second depth below the first depth; and taking any thermal images of the surface of the sample at a further time distances Δtn from any subsequent triggering of the heat pulse which further time distances Δtn are characteristic for gradients in heat flow velocity in further depths lying deeper as the second depth; and extracting from the thermal images an indication of the presence of any gradients of heat flow velocity at the respective depth distances from a surface of the sample. The system is configured to carry out the above method.