Generation of narrowband antisymmetric lamb waves using a formed laser source in the ablative regime

Cosenza, C.; Kenderian, Shant; Djordjevic, B. Boro; Green, R.E.; Pasta, A.

doi:10.1109/tuffc.2007.220

Cited by 36 publications

(19 citation statements)

References 24 publications

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“…These challenges may be solved by measurements done without contact; non-contact mode tuned ultrasonic guided wave measurements can be performed using, e.g., electro-magneto-acoustic transducers (EMATs), 15 airborne ultrasound transducers, 16 and lasers. 17 In addition, flashlamp-based excitation 18 could be used for mode tuning with suitable masks. EMATs permit spatial modulation of the transmitted signal whereas in airborne ultrasound measurements one can select the angle of sound incidence to have mode tuning.…”

Section: Introductionmentioning

confidence: 99%

“…19 Laser excitation also allows a larger stand-off than the previous modalities. 20 To achieve laser ultrasonic mode tuning, spatial modulation of the laser excitation can be done with lenticular lenses, 17,21 optical diffraction gratings, 22 laser interference patterns, 23 and transmission masks. 19 Temporal laser beam modulation can be done with a Bragg cell 24 or by modulating the intensity of a continuous wave (CW) laser.…”

Section: Introductionmentioning

confidence: 99%

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Phase-delayed laser diode array allows ultrasonic guided wave mode selection and tuning

Karppinen

Salmi

Moilanen

et al. 2013

Journal of Applied Physics

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(2013). Phase-delayed laser diode array allows ultrasonic guided wave mode selection and tuning. Journal of Applied Physics, 113 (14) Selecting and tuning modes are useful in ultrasonic guided wave non-destructive testing (NDT) since certain modes at various center frequencies are sensitive to specific types of defects. Ideally one should be able to select both the mode and the center frequency of the launched waves. We demonstrated that an affordable laser diode array can selectively launch either the S 0 or A 0 ultrasonic wave mode at a chosen center frequency into a polymer plate. A fiber-coupled diode array (4 elements) illuminated a 2 mm thick acrylic plate. A predetermined time delay matching the selected mode and frequency was employed between the output of the elements. The generated ultrasound was detected by a 215 kHz piezo receiver. Our results imply that this array permits non-contacting guided wave ultrasonic NDT. The solution is small, affordable, and robust in comparison to conventional pulsed lasers. In addition, it does not require experienced operators. V C 2013 AIP Publishing LLC.[http://dx

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phase-delayed laser diode array allows ultrasonic guided wave mode selection and tuning

Karppinen

Salmi

Moilanen

et al. 2013

Journal of Applied Physics

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“…Different modes interfere and present an obstacle to signal interpretation. The advantage of generating narrowband Lamb waves with a fixed wavelength is that the dominant frequency contents and their traveling speeds of different modes can be determined from the dispersion curves [8,28,32]. Fig.…”

Section: Frequency and Traveling Speed Evaluation Of Narrowband Lamb mentioning

confidence: 99%

“…To simplify signals in thin structures, generation of narrowband Lamb waves is desirable. Some investigators used spatial arrays illumination sources produced by several means, including the use of shadow mask [8,[22][23], optical diffraction gratings [24], multiple lasers [25], interference patterns [26][27] and lenticular arrays [28][29][30]. Among them, shadow masks are economical, effective and easy to implement (referred as pattern source in this paper), but they are not flexible and have some disadvantages.…”

Section: Introductionmentioning

confidence: 99%

Fundamental study of laser generation of narrowband Lamb waves using superimposed line sources technique

Ume

2011

NDT & E International

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“…Description of mechanisms and patterns for ultrasonic waves generated by a laser source (point, line, and array) in the three different regimes (thermoelastic, ablative, and constrained surface) can be found in References [10,19,20]. The use of an array of laser sources to generate narrow-band ultrasonic signals and phased array single pulses, with a significant increase in the sensitivity, is shown in References [21,22].…”

Section: Ultrasonic Systemmentioning

confidence: 99%

Detection of Disbonds in Multi-layer Structures by Laser-Based Ultrasonic Technique

Cerniglia

Montinaro

Nigrelli

2008

The Journal of Adhesion

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Adhesively bonded multi-layer structures are frequently used, mostly in the aerospace industry, for their structural efficiency. Nondestructive evaluation of bond integrity in these types of structures, both after manufacturing and for periodic inspection during service, is extremely important.A laser-based ultrasonic technique has been evaluated for non-contact detection of disbonds in aluminum multi-layer structures. Two configurations have been used to detect disbonded areas: pitch-catch with unidirectional guided wave scan and through-transmission with bidirectional scan. Guided wave scanning was done with a laser line source and air-coupled transducer sensing at 500 kHz, 1 MHz, and 2 MHz. Signals showed attenuation of the main frequency component and frequency shift on disbonded areas, whereas, a regular and standard waveform is seen outside disbonds. In through-transmission the longitudinal wave at normal incidence was monitored with a 1 MHz probe. One sample showed, besides the introduced inserts, other disbonded areas. After the ultrasonic measurements the sample was cut to visually check adhesive and interfaces.The guided wave pitch-catch scan allowed fast inspection and quick indication of disbonded zones, while the through-transmission C-Scan provided better definition of defects but was slower and required access from both sides of the test part.

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Generation of narrowband antisymmetric lamb waves using a formed laser source in the ablative regime

Cited by 36 publications

References 24 publications

Phase-delayed laser diode array allows ultrasonic guided wave mode selection and tuning

Phase-delayed laser diode array allows ultrasonic guided wave mode selection and tuning

Fundamental study of laser generation of narrowband Lamb waves using superimposed line sources technique

Detection of Disbonds in Multi-layer Structures by Laser-Based Ultrasonic Technique

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