Abstract: A ring of transmitter and receiver transducer arrays circumbscribes an object to be scanned. Semicircular wave fronts of ultrasound energy are propagated from different points around the ring of transducers by triggering the transmitter arrays in sequence. The reflected and transmitted ultrasound energy picked up by the receiver arrays is then electronically analyzed and a synthetically focused image corresponding to the scanned object is reconstructed on a display screen. Surprisingly high quality resolution for the reconstructed images is achieved by carefully controlling the type of waveform from which the displayed image is reconstructed. In one embodiment of the invention, the signals received by the receiver arrays are processed by a waveshaping circuit to achieve the desired waveform. In a second embodiment of the invention, the desired waveform is generated by a waveform generator circuit and transmitted by the transmitter arrays.

Abstract: A transducing unit comprising a central section, detecting echoes returned through only a small portion of a relatively large aperture lens, surrounded by an annular section, detecting echoes returned through the remainder of the aperture, provides detected signals from the respective central and annular sections which are selectively utilized during respective specified time intervals in accordance with the operation of time-controlled switches to thereby change the effective depth of focus of the lens as a function of time.

Abstract: A device for forming acoustical images comprises an ultrasonic source, a linear array of first receiving transducers for receiving the echoes from a target illuminated by a source. The signals from the linear array of first receiving transducers are processed by a system comprising an oscillator at a frequency higher than that of the source, and, for each said receiving transducers, a mixer, a filter for separating the components of the beating frequency and a transmitting transducer.

Abstract: A receiver probe for ultrasonic energy is described in which the surface deformation caused by compressive wave energy affects a thin gas-filled gap, its width being in the order of 10.sup.-7 meter. The gap is formed by opposing surfaces of an optical prism and an optical interference means. A beam of light is conducted to the boundary surface between the prism and gas. Changes in reflected and/or transmitted light beam portions resulting from compressive wave energy induced changes in gap width are sensed by opto-electric means.

Abstract: A method and apparatus for facilitating examination of an object within an optically opaque body through the use of impulse-echo techniques by projecting to an observation point, via a reflective surface positioned to intersect a line between the observation point and the object to be examined, a virtual image of a linear array of luminous points corresponding to echo-producing points of the object, such that each luminous point of the reflected image appears at a location, relative to the observation point, that coincides with the actual location of the corresponding echo-producing point of the object in the body.

Abstract: N elementary transducers are distributed regularly along a line of scanni An ultrasonic frequency receiver is associated with phase lag means. The distribution over n successive elementary transducers of the phases corresponding to focusing at a predetermined distance or several successive distances from the line is stored. That distribution corresponds to several Fresnel zones. Switches first connect a generator to a group of n' transducers corresponding to the central Fresnel zone of said stored distribution and later connect a group of n transducers to the receiver direct and via the phase lag means according to the stored distribution(s). The groups of n' and n elementary transducers are shifted along the line at intervals of time. The phase lag means may consist of inverter means causing a phase angle of .pi..