SiGnal Processing Techniques For Nondestructive Evaluation Using Laser Ultrasonics

Klein, Martin; Ansari, Homayoon

doi:10.1109/isspit.2009.5407572

Cited by 4 publications

(4 citation statements)

References 3 publications

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“…A Q-switched Nd:YAG laser, called generation laser, was used to generate ultrasonic pulses in aluminum samples. This type of laser can generate the longitudinal, shear and surface waves [33][34][35]. The Qswitched laser (wavelength of 1064 nm) was operated at single shot with energy of 420 mJ and a pulsewidth of 9 ns in all subsequent experiments.…”

Section: C Ultrasound Detectionmentioning

confidence: 99%

High sensitivity fiber optic angular displacement sensor and its application for detection of ultrasound

Sakamoto¹,

Kitano

Pacheco

et al. 2012

Appl. Opt.

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In this paper, we report on the development of an intensity-modulated fiber-optic sensor for angular displacement measurement. This sensor was designed to present high sensitivity, linear response, and wide bandwidth and, furthermore, to be simple and low cost. The sensor comprises two optical fibers, a positive lens, a reflective surface, an optical source, and a photodetector. A mathematical model was developed to determine and simulate the static characteristic curve of the sensor and to compare different sensor configurations regarding the core radii of the optical fibers. The simulation results showed that the sensor configurations tested are highly sensitive to small angle variation (in the range of microradians) with nonlinearity less than or equal to 1%. The normalized sensitivity ranges from 0.25 × V max to 2.40 × V max mV ∕ μrad (where V max is the peak voltage of the static characteristic curve), and the linear range is from 194 to 1840 μrad. The unnormalized sensitivity for a reflective surface with reflectivity of 100% was measured as 7.7 mV ∕ μrad. The simulations were compared with experimental results to validate the mathematical model and to define the most suitable configuration for ultrasonic detection. The sensor was tested on the characterization of a piezoelectric transducer and as part of a laser ultrasonics setup. The velocities of the longitudinal, shear, and surface waves were measured on aluminum samples as 6.43, 3.17, and 2.96 mm ∕ μs, respectively, with an error smaller than 1.3%. The sensor, an alternative to piezoelectric or interferometric detectors, proved to be suitable for detection of ultrasonic waves and to perform time-of-flight measurements and nondestructive inspection.

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Section: C Ultrasound Detectionmentioning

confidence: 99%

High sensitivity fiber optic angular displacement sensor and its application for detection of ultrasound

Sakamoto¹,

Kitano

Pacheco

et al. 2012

Appl. Opt.

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“…One significant advantage of this technique is that non-contact laser ultrasonic signals can be processed at high temperatures or moving at high speeds [3]. Detailed analysis of results including characterization of flaw types has been attempted [4].…”

Section: Deposited Tmentioning

confidence: 99%

Defect detection in laser powder deposition components by laser thermography and laser ultrasonic inspections

et al. 2013

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Laser Powder Deposition (LDP) techniques are being adopted within aerospace and automotive manufacturing to produce innovative precision components. Non-destructive techniques (NDT) for detecting and quantifying flaws within these components enables performance and acceptance criteria to be verified, improving product safety and reducing ongoing maintenance and product repair costs.In this work, software enabled techniques are presented for in-process analysis of NDT laser ultrasonic signals and pulsed laser thermography images of sequential metallic LPD layers. LPD tracks can be as thin as 200µm while deposited at a rate of 500 mm/min, requiring ultrafast inspection and processing times. The research developed analysis algorithms that allow senior engineers to develop inspection templates and profiles for in-process inspection, as well as an end-to-end, user friendly interface for engineers to perform complete manual Laser Ultrasonic or Laser Thermographic inspections.Several algorithms are offered to quantify the flaw size. location and severity. The identified defects can be imported into a sentencing engine which then automatically compares analysis results against the user defined acceptance criteria so that the manufacturing products can be verified. Where both laser ultrasonic and laser thermographic NDT data is available further statistical tools could increase the confidence level of the inspection decision.

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“…The initial temperature of the models is o 35 C . We take the increase of temperature as heat conduction in the main physical processes without considering convection and radiation effects.The properties of adipose tissue and inclusion [1,2] used in the calculation are listed in Table 1 [9,10] . Absorption coefficient(cm -1 ) β 1…”

Section: Laser and Materials Parametersmentioning

confidence: 99%

“…It has been recognized as a powerful tool for nondestructive materials testing and evaluation. Laser ultrasonic has gained widely application in the detection of the defects in the metal plate [1] , metal fatigue and casing corrosion [2] , measuring the thickness of steel [3] and so on. The laser ultrasonic signals are not only relevant to laser parameters, but also closely associated with physical properties of the targets materials.…”

Section: Introductionmentioning

confidence: 99%

Study of laser ultrasonic in adipose tissue by the optical absorption coefficient of inclusions

Luo

Shen

2011

SPIE Proceedings

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Based on the thermo-elastic mechanism of a pulsed laser in adipose tissue with inclusions，the physical model of generation and transmission of the ultrasound was established. The transient responses of the single pulsed laser interacting with adipose tissue were presented by means of numerical simulation, meanwhile the corresponding stress field and the transmission of the resultant ultrasound were also investigated. By analyzing the laser-induced ultrasonic waveforms in different positions, we found that when the laser acts on the adipose tissue with inclusions, the inhomogeneity of the tissue leads to different ultrasound modes. This can be attributed to the difference of the optical absorption coefficient between adipose tissues and inclusions. The larger optical absorption coefficient of inclusion in the adipose tissue, the narrower of the full width at half maximum of laser ultrasound signal waveform. Full width at half maximum of laser ultrasound signal waveform of a pure adipose tissue is wider than that of the adipose tissue with inclusions. The resultant ultrasound signal waveform has larger amplitude in the inclusions with larger optical absorption coefficient than in the pure adipose tissue. The laser ultrasound signal waveform of the adipose tissue with inclusions has a multiple-interface reflected wave. These results can provide valuable information about further research on methods and techniques of ultrasonic noninvasive detection of biological organization.

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SiGnal Processing Techniques For Nondestructive Evaluation Using Laser Ultrasonics

Cited by 4 publications

References 3 publications

High sensitivity fiber optic angular displacement sensor and its application for detection of ultrasound

High sensitivity fiber optic angular displacement sensor and its application for detection of ultrasound

Defect detection in laser powder deposition components by laser thermography and laser ultrasonic inspections

Study of laser ultrasonic in adipose tissue by the optical absorption coefficient of inclusions

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