MEASUREMENT OF THE THICKNESS OF LAYERS OF MATERIAL BY ULTRASONIC INTERFEROMETRY

The invention relates to a method for the automatic correction of the variations of efficiency of an electroacoustic transducer as a function of the frequency for improving the accuracy of a device measuring the thickness of layers of materials by ultrasonic interferometry. It is characterized in that: PA1 among the echoes generated are detected, on the one hand, a beat echo characteristic of the echo interference in the medium (1) considered and, on the other hand, an echo called pilot echo offet from the beat echo and whose amplitude is characteristic of the electroacoustic conversion factor of the transducer, PA1 the level of the pilot echo is compared with a predetermined reference (24) and a command (25) is elaborated proportional to the detected difference, PA1 as a function of this command, through a corrector means (26) situated upstream of the echo processing device (9), the amplitude of the signals representative of the beat echo and of the pilot echo is influenced uniformly, PA1 the method is repeated from the initial step.