Abstract: An ultrasonic probe for an ultrasonic medical diagnostic apparatus which is composed of a piezoelectric vibrator with electrodes attached onto both surfaces thereof and one or two acoustic matching layers which are provided on the surface of one electrode of the piezoelectric vibrator. One of the acoustic matching layers is made of thermosetting resin such as epoxy resin mixed with magnetic material. A backing load member which is made of ferrite rubber or plastic mixed with tungsten powder is provided on the surface of the other electrode of the piezoelectric vibrator. An acoustic lens which is made of silicone rubber may be disposed on the upper acoustic matching layer. The acoustic matching layers may be formed by pouring the materials, thereby to form the ultrasonic probe without an intermedium of a different kind of material on the piezoelectric vibrator.

Abstract: An ultrasonic probe for use in ultrasonic imaging systems includes an array of piezoelectric transducer elements. The array is backed by a rear member of an energy absorbing material composed of a mixture of urethane rubber and microballoons. The rear member has a Shore-A hardness greater than 85, an ultrasonic absorption coefficient greater than 1.5 dB/mm at the frequency of energy generated by the array and an acoustic impedance in the range between 1.0.times.10.sup.5 g/cm.sup.2 sec and 3.0.times.10.sup.5 g/cm.sup.2 sec. Alternatively, the rear member is composed of a mixture of thermosetting resin, microballoons and solid particles. Preferably, a thermosetting resin layer is provided between the array and the rear member to ensure against disconnection of wire leads from transducer electrodes.