Broadband Ultrasound Propagation Using Sonic ...

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Using Sonic Crystal and Nonlinear. Medium. Dipen N. ... of Sonic crystal .... Sonic. Crystal. Inside FC-43. Highest. Lowest. Intensity. Color map. Intensity. 0 .5 1.0 ...
Broadband Ultrasound Propagation Using Sonic Crystal and Nonlinear Medium Dipen N. Sinha and Cristian Pantea Los Alamos National Laboratory Los Alamos, New Mexico, USA

ICA 2013 Montreal June 2013

Unidirectional Low-Frequency Sound Transmission Through Passive Wall as a Collimated Beam with High Bandwidth Underwater 200 kHz – 1 MHz (Sonar) Modulated with highfrequency carrier (fc)

Collimated beam (signal frequency)

signal No transmission

Sound transmission

No transmission

Output

Low frequency

Fc > 2 MHz

High frequency

Input Distance ~ 1 MHz (Bandwidth) High-frequency window

> 50 cm

Only signal or only carrier: No Transmission

Concept of an Ideal Device (Wall) Signal, fm

(200 kHz ∆𝑓

∆f = signal bandwidth

BW

fc

fm

∆f/2 Frequency Modulated input signal

Frequency Bandgap and Bandpass of Sonic crystal

Frequency Demodulated and collimated signal

Theoretical Sonic Crystal Sound Transmission Designed Band gap and Band pass

Transfer-Matrix Method:

Alternate Layers of Microscope Glass Slides & FC-43

Normalized Transmission Amplitude

1.0

19 layers Glass: 1 mm FC-43: 0.23 mm

0.5

Impedance: Glass: 12.6 MRayl FC43: 1.2 MRayl

0.0 1.0

7 layers Glass: 1 mm FC-43: 0.23 mm

0.5

0.0 1.0

Liquid

Solid

Used for experiment

7 layers Glass: 1 mm FC-43: 0.7 mm

0.5

0.0 0.0

0.5

Signal EXIT window

1.0

1.5

2.0

Frequency (MHz)

2.5

3.0

3.5

Signal ENTRY window

Acoustic Nonlinear Medium: Frequency Mixing and Collimated Beam Generation Flourinert (FC-43) Primary frequencies f1

Frequency Mixing Region Rayleigh Distance (πfd2/c) Virtual sources

AM signal or Two frequencies f 2

Highly directional beam ∆f = f1 - f2

End-fire Array

Ultrasonic Transducer Diameter (d)

Water

Absorption length (1/α)

No sum or higher frequencies f1 f2

fc Demodulated Signal (fm)

fc±fm

fm Output

Frequency

sidebands Input

Down-converted Signal (∆f)

∆f Output

Frequency

Input

Simple Low-Pass Filter (High Frequency Blocking) Blocks carrier and other high frequencies in both directions 0

Experimental Data

1.7 mm thick cork layer

Transmission Amplitude (dB)

-20

-40

-60

-80

Signal

-100

-120 0

200

400

600

Frequency (kHz)

800

1000

Experimental Setup Sonic Crystal Glass plate: 20 x 20 mm Thickness: 1 mm Spaced: 0.7 mm

Waveform Generator

Computer PC

Position controller

Digital Oscilloscope

Power Amplifier

Amplifier

Plexiglas tube

X-Y-Z positioner

Sheet of Rubber cork

60 mm

Transducer PZT-4 Fc: 3 MHz Broadband Diam: 20 mm

FC-43 Array of glass plates

82 mm

Receiver Water Tank Transducer

1.7 mm thick cork

Experimental Details Input Signal (Two types) fm

Device SC

NL

LP Detected Signal

fc

55 mm

AM modulation

fm

or

or ∆f = f1-f2

f1 + f2

82 mm 105 µs

Dual frequency

water

Duration: 50 µs

0.20

Peak value

0.15

Tukey Envelope

0.5

0.10 0.05

Amplitude

Input

Amplitude

1.0

Output

0.00 -0.05 -0.10

0.0

-0.15 0

20

40

60

Time (µs)

80

100

-0.20 0

20

40

60

80

Time (µs)

100

120

140

Experimental Sound Transmission of Glass-Fluorinert Sonic Crystal

Normalized Transmission

1.0

Frequency Sweep Network Analyzer CW Measurements

SC + NL (FC-43) SC only

0.8

0.6

0.4

0.2

0.0 0.0

0.5

1.0

1.5

2.0

Frequency (MHz)

2.5

3.0

SC Transmission Spectrum: Comparison with Theory 1.0

Frequency Sweep Network Analyzer CW Measurements

Theory Experiment

Amplitude

0.8

Glass:

Density: 2.240 g/cm3 Sound speed: 5640 m/s Thickness: 1.0 mm

0.6

FC43:

0.4

Density: 1.88 g/cm3 Sound speed: 655 m/s Thickness: 0.73 mm

0.2

0.0 0.0

0.5

1.0

1.5

2.0

Frequency (MHz)

2.5

3.0

3.5

SC Transmission Spectrum: Comparison with Theory Best Fit 1.0

Frequency Sweep Network Analyzer CW Measurements

Normalized Amplitude

Theory Experiment

Only thickness adjusted

Glass:

0.5

Density: 2.240 g/cm3 Sound speed: 5640 m/s Thickness: 0.998 mm

FC43:

0.0 0.0

Density: 1.88 g/cm3 Sound speed: 655 m/s Thickness: 0.745 mm 0.5

1.0

1.5

2.0

Frequency (MHz)

2.5

3.0

3.5

Difference Frequency Beam at 300 kHz in Fluorinert (FC-43) Experiment conducted in a Fluorinert-filled tank Inside FC-43

Sonic Crystal

Input f1: 3.1 MHz f2: 2.8 MHz Intensity Color map Intensity

Highest

Lowest Not present at output 0

.5

1.0

1.5

2.0

2.5

3.0

3.5 (MHz)

Axial intensity profile of the beam 1.0

Experimental data KZK simulation

Non-linear model KZK (Khokhlov-Zabolotskaya-Kuznetsov) nonlinear parabolic equation

Normalized Amplitude

0.8

∂ 2 p c0  ∂ 2 p 1 ∂p  D ∂3 p β ∂2 p2 + =  + + ∂z∂t ' 2  ∂r 2 r ∂r  2c0 3 ∂t ' 3 2 ρ 0 c0 3 ∂t ' 2

0.6

0.4

Used Texas KZK Code

0.2

0.0 0

20

40

60

80

100

120

140

160

180

Axial distance (mm)

200

Diffraction

Absorption

Parameters for KZK Model:

Primary frequencies: 2.85 and 3.1 MHz Median frequency: 2.95 MHz Median pressure of the primaries: 55 kPa; Source diameter (SC outside surface opposite the transducer): 20 mm;

FC-43 Properties:

β: 7.6; Density: 1850 kg/m3 ; Sound speed: 646 m/s ; Absorption parameter: 6.17 Nonlinear parameter (ratio of Rayleigh length and Shock length): 22.29.

Nonlinearity

Transmission Amplitude (relative units)

Experimental Sound Transmission – Reverse Direction Very low transmission 0.003

Sonic crystal band gap

0.002

Low pass filter

0.001

No measurable transmission

0.000 0.0

0.5

1.0

1.5

2.0

Frequency (MHz)

2.5

3.0

Profiles of the Sound Beam Exiting from the Device into Water Demodulated Signal

Difference Frequency: 300 kHz

Carrier: 2.95 MHz AM signal: 220 kHz

f1: 3.1 MHz; f2: 2.8 MHz

(a)

(b)

Conclusions • Sound transmission through a device in the frequency range (200-400 kHz) has been demonstrated by taking advantage of the band gap and band pass characteristics of a sonic crystal combined with a nonlinear medium, and a low pass filter. • The key to this device is the modulation of a high frequency carrier with the desired low frequency signal within the band pass region of the sonic crystal and subsequent demodulation of the signal in a nonlinear medium. • Neither the low frequency nor the high frequency carrier alone can pass through the device because of the band gap of the sonic crystal and a low pass filter. • The signal exiting from the device is in the form of a collimated beam • The sound transmission characteristics of the device is unidirectional except at very low frequency

THANK YOU

Sonic Crystal Transmission Characteristics Repeated Pattern

Tranmission Amplitude

1.0

0.8

0.6

0.4

0.2

0.0 0

1

2

3

4

Frequency (MHz)

5

6

Sonic Crystal transmission with and without going through nonlinear medium 1.0

SC + NL

0.8

Normalized Transmission

0.6 0.4 0.2

(a)

0.0 0.0

0.5

1.0

1.5

2.0

2.5

3.0

2.0

2.5

3.0

SC only

1.0 0.8 0.6 0.4 0.2

(b)

0.0 0.0

0.5

1.0

1.5

Frequency (MHz)

Frequency mixing due to resonance in sonic crystal liquid layer Liquid layer is acoustically nonlinear 0.1

Amplitude

Amplitude

1.0

0.5

0.0

-0.1

0.0 0

20

40

60

80

0

100

10

20

30

40

50

60

70

80

90

100

Time (µs)

Time (µs)

0.8

1200

Output Signal Input Signal

1200

0.7

800

600

400

0.6 800

0.5

Generated in SC liquid layer

0.4

600

0.3 400 0.2

200

200

0.1 0 0.0

0.5

1.0

1.5

2.0

2.5

Frequency (MHz)

3.0

3.5

4.0

0

0.0 0.0

0.5

1.0

1.5

2.0

2.5

Frequency (MHz)

3.0

3.5

4.0

FFT (Input Signal)

1000

FFT (Output Signal)

FFT Amplitude

1000