Ultrasonic echographic device incorporating a probe with adjustable focal length and means of obtaining a large depth of field with a high resolving power

摘要

The device incorporates a probe with a focal length adjustable by varying the curvature of the convex face of a plano-convex acoustic lens contained in it; it is characterised in that the probe 1 consists of a disc 10 made of a piezoelectric ceramic forming at least two concentric elementary transducers 101-102, of a membrane 11 shaped like a spherical cap forming with the disc a mainly closed chamber containing a liquid of acoustic index greater than that of water and of means for varying the curvature of the membrane so as to adjust the focal length of the probe; and of means 2 for switching on or off at least one of the elementary transducers 102 in order to alter the active surface area of the probe. IMAGE