Patent ID: 6305225
Filing Date: 2001-10-23
Classification: G01S,G10K

Abstract:
A focusing delay method in an ultrasonic signal focusing medium for focusing an ultrasonic signal returning from a focal point on an object in a medium via an array transducer including a plurality of transducer elements, the ultrasonic signal focusing method comprising the steps of:(a) estimating a travelling distance of an ultrasonic signal returning from the focal point and points adjacent to the focal point;(b) estimating an ultrasonic signal travelling velocity at the medium including an object so that a receipt time at a transducer element located at the center of the array transducer is fixed as a reference time and corresponds to the estimated travelling distance;(c) obtaining a travelling distance of the ultrasonic signal to the focal point using the estimated ultrasonic signal travelling velocity and calculating a focusing delay time according to the travelling distance, thereby obtaining a focusing time delay curve;(d) varying the estimated ultrasonic signal travelling velocity and using the reference time and each of the varied ultrasonic signal travelling velocity to obtain a travelling distance of the ultrasonic signal to the focal point corresponding to each of the ultrasonic signal travelling velocity;(e) calculating a focusing delay time according to the travelling distance of each of the ultrasonic signal and obtaining a respective focusing time delay curve, and from the focusing time delay curve, forming a calculated ultrasonic image and obtaining brightness or contrast of the calculated ultrasonic image;(f) determining a corresponding travelling velocity obtained when the brightness or contrast of the ultrasonic image in step (e) becomes maximum as an average ultrasonic signal travelling velocity at the medium and then determining the corresponding focusing time delay curve as the optimal focusing time delay curve and the optimal ultrasonic image.