Apparatus for examining objects by ultrasonic echography

Apparatus for examining objects by ultrasonic echography, comprising an array of m ultrasonic transducer elements, where m is a positive integer, a transmission stage, having n transmission channels, where n is a positive integer less than or equal to m, associated with n transducer elements, among said m elements, defining an ultrasonic aperture, said transmission stage together with said array of transducer elements being means for transmission of ultrasonic signals to the object to be examined, a receiving and processing stage, having n receiving channels associated with said n transducer elements, said receiving and processing stage together with said array of transducer element being means for receiving and processing echographic signals returned to said n transducer elements by the object being examined, said transmission stage comprising transmission-mode means for focusing by the provision of suitable delays in said n transmission channels and said receiving and processing stage comprising receiving-mode means for focusing by the provision of suitable delays in said n receiving channels, the receiving and processing stage further comprising:

• associated with said n receiving channels, means for determining (n-1) correction values for the focusing delays;
• and
• means for correcting said focusing delays as a function of the (n-1) correction values thus determined;
• wherein said determining means comprises, in parallel, (n-1) correction circuits each correction circuit being coupled for receiving two focused echographic signals from a different pair of outputs, in i.sup.th and (i+1).sup.th adjoining channels, where i is a positive integer less than n, of the receiving-mode focusing means and each of said correction circuits being means for determining an i.sup.th of said (n-1) correction values, each correction circuit comprising:
• means for generating a time window signal defining a time window during with the i.sup.th correction value is determined;
• and
• means for determining, during said time window, a phase shift between the two focused echographic signals received by said correction circuit, said phase shift constituting the i.sup.th correction value or being directly related to it, said determining means not including any correlators.