US 4,070,643 A · Acoustic holography apparatus

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. The sampling system may include a switch circuit arranged to apply a series of predetermined voltages in sequence to a comparator controlling a sampling gate.

Claims12

Dependent claims

Acoustic holography apparatus comprising:

acoustic transmitter means for insonifying an article or object for examination,
an acoustic receiver transducer for detecting acoustic signals from the acoustic transmitter means which have passed by or through the said article or object or have been diffracted or reflected therefrom,
scanning means for producing a displacement of the acoustic receiver transducer relative to the object,
sampling means for taking substantially instantaneous samples of the amplitude of a signal derived from the acoustic receiver transducer at instants selected relative to the phase of the signal transmitted by the acoustic transmitter means, the selected instants being dependent on the current position of the receiver transducer and being determined according to the phase of a chosen notional reference wave at the current position of the receiver transducer relative to the phase of the chosen notional reference wave at a datum point, and
plotting means for plotting the samples taken by the sampling means versus the displacement of the acoustic receiver transducer so as to form a graphical diagram representing an acoustical hologram of the object.

2 more elements

A method for forming an acoustic hologram pattern which comprises:

insonifying an object with acoustic waves from a transmitter transducer;
sampling the instantaneous amplitude of a signal representing or derived from the resultant disturbance due to acoustic waves reflected from the object at each of a plurality of positions in a plane at selected phase times relative to the phase of the acoustic waves at the transmitter transducer, the selected phase time in each case being determined according to a prescribed relationship with parameters specifying the position concerned;
and
forming the hologram pattern by plotting the sampled amplitudes from various positions in the plane at corresponding positions in a diagram of the plane.

1 more element

Dependencies are inferred from the claim text.

Acoustic holography apparatus

Life of this patent

Acoustic holography apparatus

Life of this patent

Abstract

Claims12