Acoustic concealed item detector
First Claim
1. An acoustic concealed item detector, comprising:
- a multi-frequency ultrasonic wave generator for generating in a gaseous medium, at least a first ultrasonic wave having frequency f1, and a second ultrasonic wave having frequency f2, the frequencies f1 and f2 both being between 100 KHz and 200 KHz, the multi-frequency ultrasonic wave generator being arranged such that in operation, the first ultrasonic wave and the second ultrasonic wave are focused to a prescribed mixing zone having a characteristic size of less than about 0.2 cm, within which a difference-frequency acoustic wave is produced, the difference-frequency acoustic wave having a frequency less than about 20 KHz;
a receiver sensor for detecting interactions of the difference-frequency acoustic wave and producing corresponding electromagnetic signals; and
a system processor for processing the electromagnetic signals and identifying signals indicative of concealed items.
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Abstract
The present invention is directed towards an acoustic concealed item detector and related methods for detection using acoustics. In an illustrative embodiment, a multi-frequency ultrasonic wave generator generates in a gaseous medium at least first and second ultrasonic waves. The multi-frequency ultrasonic wave generator is arranged such that in operation, the first ultrasonic wave and the second ultrasonic wave mix in a prescribed mixing zone to produce a difference-frequency acoustic wave. A receiver sensor detects the difference-frequency acoustic wave and produces corresponding electromagnetic signals. The electromagnetic signals are processed by a system processor and signals indicative of concealed items are identified. Preferably the ultrasonic waves are focused to a small prescribed mixing zone. Parametric and multi-transducer embodiments are disclosed.
30 Citations
43 Claims
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1. An acoustic concealed item detector, comprising:
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a multi-frequency ultrasonic wave generator for generating in a gaseous medium, at least a first ultrasonic wave having frequency f1, and a second ultrasonic wave having frequency f2, the frequencies f1 and f2 both being between 100 KHz and 200 KHz, the multi-frequency ultrasonic wave generator being arranged such that in operation, the first ultrasonic wave and the second ultrasonic wave are focused to a prescribed mixing zone having a characteristic size of less than about 0.2 cm, within which a difference-frequency acoustic wave is produced, the difference-frequency acoustic wave having a frequency less than about 20 KHz;
a receiver sensor for detecting interactions of the difference-frequency acoustic wave and producing corresponding electromagnetic signals; and
a system processor for processing the electromagnetic signals and identifying signals indicative of concealed items. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An acoustic concealed item detector, comprising:
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a multi-frequency ultrasonic wave generator for generating parametrically with a single transducer at least a first focused ultrasonic wave and a second focused ultrasonic wave;
the multi-frequency ultrasonic wave generator being arranged such that in operation the first focused ultrasonic wave and the second focused ultrasonic wave are focused to a prescribed mixing zone, a difference-frequency acoustic wave being produced from the interaction of the first focused ultrasonic wave and the second focused ultrasonic wave;
a receiver sensor for detecting interactions of the difference-frequency acoustic waves and producing corresponding electromagnetic signals; and
a system processor for processing the electromagnetic signals and identifying signals indicative of concealed items. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method for detecting a concealed item behind a fabric or material-covered target area, the method comprising:
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generating a localized acoustic wave with a frequency below 20 KHz;
scanning the target area with the localized acoustic wave;
sensing interactions of the localized acoustic wave;
identifying patterns of interactions indicative of concealed items. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. A method for high-resolution scanning of a target, comprising:
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mixing ultrasonic waves in a gaseous medium to produce a difference-frequency acoustic wave having a difference-frequency acoustic wave wavelength inversely proportional to the difference frequency, the difference-frequency acoustic wave having a localized effective source confined to a scanning spot that is small relative to the difference-frequency acoustic wave wavelength;
scanning the target with the scanning spot;
sensing interactions of the difference-frequency acoustic wave;
determining target information from the interactions of the difference-frequency acoustic wave. - View Dependent Claims (41)
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42. An acoustic concealed item detector, comprising:
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a multi-frequency ultrasonic wave generator for generating at least a first ultrasonic wave, and a second ultrasonic wave, the multi-frequency ultrasonic wave generator being arranged such that in operation, the first ultrasonic wave and the second ultrasonic wave mix in a prescribed mixing zone within which a difference-frequency acoustic wave is produced;
a vibrometer for detecting interactions of the difference-frequency acoustic wave and producing corresponding electromagnetic signals; and
a system processor for processing the electromagnetic signals and identifying signals indicative of concealed items. - View Dependent Claims (43)
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Specification