Evaluation of the Ultrasonic Preamplifier Noise Voltage Density

Svilainis, Linas; Dumbrava, V.; Kybartas, Darius

doi:10.1142/s0218126614500078

Cited by 8 publications

(7 citation statements)

References 5 publications

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“…The reflected and transmitted signals were amplified using a PA1008 preamplifier (AUT Solutions, US, TX). The preamplifier had a high voltage protection circuit, 1 kΩ input impedance [26]. An acquisition system of our own design [27] was used for data acquisition.…”

Section: Resultsmentioning

confidence: 99%

High frequency focused imaging for ultrasonic probe integrity inspection

Svilainis

Kybartas

Aleksandrovas

et al. 2020

NDT & E International

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Most ultrasonic probes present a layered structure that may comprise delay lines, acoustic lens, wear plates, matching layers, electrodes, piezoelectric layers, and a backing block. Probe integrity can be compromised by different defects, such as deficient bonding, presence of air bubbles or porosity, lack of electrical conductivity in electrodes, and deviations in the layers' acoustic thicknesses, impedances or attenuation values. Conventional testing procedures are based on the integral properties of the probe, such as acoustic directivity, sensitivity, and electrical impedance. An alternative technique for the non-destructive inspection of the probe's integrity is presented in this study. The proposed technique is based on imaging of the internal structure using a higher frequency focused ultrasound. Scanning the probe's surface using this focused beam provides two imaging modes: reflection and transmission. In the reflection mode, the higher intensity of the echoes indicates the presence of the defects, such as disbonds, poor acoustic matching or porosity. The main novelty of the proposed technique is in the transmission mode: the probe's electric response to the high frequency focused beam is used to get a 2D distribution of transduction efficiency. Moreover, the probe's response can be gated to separate, both front and back side, responses in the time domain, so the local integrity of an electroacoustic structure is evaluated. To verify the proposed technique, a focused 20 MHz transducer with a focal spot diameter of 0.35 mm was mounted on an ultrasonic scanner and immersed in water above the surface of the probe to be tested. Signals were gated by the layers' thickness, giving the C-scan images corresponding to the different material interfaces inside the tested probes: front face, matching layers, piezoelement and backing. It was demonstrated that the resulting C-scan images are informative in evaluating probe's integrity and layers' acoustic thickness. Comparison of the C-scan images obtained in the reflection and transmission modes shows a good agreement in the structure deficiencies evaluation. The technique proposed is attractive due to its simplicity. It can be useful in several applications: i) the probes already in use can be verified and if any deficiencies are detected, the information obtained can be used to evaluate and guide repair; ii) fabrication quality can be verified by confirming the adhesion of layers and parameters in 2D; and iii) the development of new fabrication routes can be guided, where adherence, compatibility, homogeneity, etc. of new materials or new technologies can be evaluated.

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Section: Resultsmentioning

confidence: 99%

High frequency focused imaging for ultrasonic probe integrity inspection

Svilainis

Kybartas

Aleksandrovas

et al. 2020

NDT & E International

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“…Toneburst and CW sinusoid signals required fundamental frequency amplitude extraction. Sine wave correlation (SWC) technique [20] was used to extract the complex voltage V (VL or VH in (1), (2) accordingly)…”

Section: Output Impedance Measurement Systemmentioning

confidence: 99%

“…More details on amplifier, used in experiments, noise evaluation can be found in [20]. Operational amplifier LMH6624 was used as preamplifier.…”

Section: Sensitivity Analysis To Select Reference Loadsmentioning

confidence: 99%

See 1 more Smart Citation

Ultrasonic Air Coupled Transducer Output Impedance Measurement Technique

Svilainis¹,

Chaziachmetovas²,

Álvarez-Arenas³

2019

ElAEE

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Estimation of the output impedance of ultrasonic transducers is required for electrical matching circuits design and for receiving amplifiers noise optimization. This paper presents a simple technique for transducer output impedance estimation using the same data acquisition system and signals that are conventionally used in non-destructive testing. A pair of ultrasonic transducers is used: one for transmission, one for reception. Received signal is recorded under low and high resistance load and transducer output impedance is then obtained from these two signals. Hence, this technique requires only one measurement channel and bias errors are low (no need for calibration). In addition, it is ground referenced and does not require the transducer to be removed from the positioning fixture. Experimental results obtained using different probing signals have been compared against conventional measurements obtained by an impedance analyser.

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“…The ability to process the ultrasonic signal digitally is offering multiple advantages. In [24] it was shown that if expected electronics noise at reception channel output entotAout is 180 nV/Hz (output noise of AD8031 at minimum gain) then no more than 20 ps jitter clock is required to avoid the clock jitter noise influence. In order to make the quantization noise influence insignificant the resolution of ADC has to be above 9 bits at 100 MHz sampling frequency.…”

Section: Signal Digitization Electronicsmentioning

confidence: 99%

Electronics for Ultrasonic Imaging System

Svilainis

Dumbrava

Kitov

et al. 2014

ElAEE

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Design of ultrasonic imaging system is presented. System has a modular structure with main acquisition and front end electronics separated in order to have minimal path for host PC connectivity and shortest path to ultrasonic transducer. Such acquisition modules placement allows reducing the induced EMI and increasing the flexibility of the system. Positioning module is also separate and allows various scanning equipment configurations. Evaluation of excitation and reception electronics parameters is presented. Essential measurement procedures outlined. Signal digitization parameters (sampling frequency, clock jitter and quantisation) were chosen to balance time of flight estimation random errors versus interpolation bias errors.

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Evaluation of the Ultrasonic Preamplifier Noise Voltage Density

Cited by 8 publications

References 5 publications

High frequency focused imaging for ultrasonic probe integrity inspection

High frequency focused imaging for ultrasonic probe integrity inspection

Ultrasonic Air Coupled Transducer Output Impedance Measurement Technique

Electronics for Ultrasonic Imaging System

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