Apparatus for the examination of media by ultrasonic echography.

摘要

The apparatus consists of an ultrasonic transducer structure (600) combined with a transmission stage (200) for the repeated emission of ultrasonic waves towards the medium to be examined. It also includes a receiving and processing stage (300) for the reception and processing of echograph signals sent back towards the said structure by the obstacles encountered by the transmitted waves. The ultrasonic transducer structure (600) is either a single broadband transducer element or an array of elementary ultrasonic transducers associated with a circuit (610) for controlling the aperture of the said array, with a switching circuit (730) and with p channels in parallel (710a) to (710p) for introducing delays in order to focus the transmission. This structure is preceded by an electrical matching circuit (700) consisting of n channels in parallel and two switching circuits with n positions placed at each end of these channels in order to select only one of them, depending on the working frequency chosen. Each of these channels of the electrical matching circuit has a filter matched to the said working frequency. The transmission stage (200) and the receiving and processing stage (300) are also matched to this working frequency. Application to medical echography. <IMAGE>