Abstract: A method and associated systems for 3D printing on the surface of an acoustic hologram uses an array of sound-wave emitters to generate a three-dimensional acoustic hologram of an object to be printed. This hologram is composed of acoustic standing waves that exert invisible acoustic radiation forces in three-dimensional space that feel like surfaces of a solid object. The resulting hologram creates a tactile illusion of an object floating in space within a three-dimensional printing area. When a 3D-printing medium is applied to the surface of the hologram, the medium solidifies on the hologram's surface to generate a hollow shell in the shape of the object to be printed.

Abstract: Sonic excitation is used to locate, without contact, an object or defect beneath a surface. Defects may include, for example, damage and flaws in load bearing concrete structures wrapped in plastic, fiberglass or composite sheathing, while buried objects amenable to detection include landmines or above-ground mines.

Abstract: A method for detecting the seismic discontinuity in acoustic impedance caused by an acoustically hard, reflective object buried a few feet below poroelastic soil using seismic activity induced through acoustic coupling with a remote sound source. The abrupt change in the soil impedance caused by the buried object causes sound to reflect between the object and the surface and increase the amplitude of the seismic vibrations induced by the incident acoustic energy. The change in the seismic displacement of the soil is on the order of angstroms which can be detected using remote optical test equipment such as a laser-doppler vibrometer (LDV) commonly used in nondestructive testing. A sound source emits sound at frequencies that induce significant seismic coupling with the poroelastic soil. Part of a beam of laser light of an LDV is scanned over the ground. The laser light is shifted in frequency from its source frequency by an amount intended to approximate the frequency of the anticipated seismic vibrations.

Abstract: An apparatus for observing a sound field of an ultrasonic wave, including a first unit which determines characteristic values of a medium at each point of a predetermined region by an ultrasonic wave having a sound field of an arbitrary form and a second unit which displays an output of the first unit as two-dimensional or three-dimensional distribution in the predetermined region, and allows control of the form of the sound field of the ultrasonic wave.

Abstract: Apparatus and method for forming acoustic hologram patterns, comprising a receiver transducer for detecting acoustic waves scattered by an object, a scanning system for moving the receiver relative to the object, a sampling system for taking samples of a signal derived from the receiver transducer at selected instants relative to the phase of the acoustic signals at the transmitter, the selected instants being determined according to the phase of a chosen notional reference wave at the position of the receiver transducer relative to the phase of the chosen notional reference wave at a datum point, and a system for plotting the samples versus the displacement of the receiver transducer so as to form a graphical diagram representing an acoustic hologram of the object. The receiver signals are preferably applied to a phase-locked frequency-multiplier circuit and the samples taken from the output of this circuit.