Improved method for inspection by the transmission of ultrasounds

An inspection method of an object (O) by ultrasound transmission, wherein a scanning of said object by an ultrasound beam and measurement of the amplitude of the ultrasound beam transmitted via said object (O) are carried out, said measurement comprising conversion of the ultrasound beam into an electrical signal, the application of an amplification gain to said signal and measurement of the amplitude of said signal, to deduce therefrom a mapping in which each point of a projection surface of said object according to the direction of exposure is associated to the amplitude of the ultrasound beam transmitted to said point via said object, the method being characterized in that it comprises the steps consisting of:

• carrying out said scanning and said amplitude measurement on a reference piece having a geometry identical to the object to be inspected, to deduce therefrom a mapping of said piece, the amplification gain applied for the amplitude measurement being a predetermined reference gain (Gref),
• determining, for a plurality of points of the mapping of the reference piece, gain corrections to be made to the reference gain (Gref) at the corresponding points of the scanning to obtain a constant amplitude of the ultrasound beam (Ac) transmitted via the reference piece for all the points of the mapping,
• carrying out said scanning and said amplitude measurement on the object to be inspected (O), by applying to the different points of the scanning an amplification gain (Gc) corresponding to the reference gain (Gref) corrected from the gain corrections previously determined.