Ultrasonic generation with a pulsed TEA CO<sub>2</sub>laser

Edwards, C.; Taylor, G.S.; Palmer, S.B.

doi:10.1088/0022-3727/22/9/004

Cited by 22 publications

(10 citation statements)

References 11 publications

(4 reference statements)

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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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“…The means of generation depend on the power density of the spot (power/area of the spot) at the surface of the material Castagnede et al, 1992;Edwards et al, 1989).…”

Section: Principles Of Laser Ultrasonics Generationmentioning

confidence: 99%

Final Technical Report of project: "Contactless Real-Time Monitoring of Paper Mechanical Behavior During Papermaking"

Lafond¹,

Ridgway²,

Jackson³

et al. 2005

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Project Objective: The objective is to provide a sensor that uses non-contact, laser ultrasonics to inspect the mechanical state of paper on-line. Tasks include optimization of ultrasound generation on moving paper, development of interferometric detection schemes for on-line operation, construction of a prototype for application on a paper machine, and development of an online sensor suitable for industrial environments. Background:Laser ultrasonic methods have the potential to succeed in the on-line environment of the mill where traditional contacting technologies have not. A critical consideration for papermakers before implementing a new sensor is the risk of web breaks. As such, they have traditionally been hesitant to embrace technologies that contact the sheet. Also, previous contacting ultrasonic measurement schemes have been difficult to apply to moving paper applications at a reasonable cost and effectiveness. By contrast, the LUS technology is a single-sided measurement that requires no contact with the sheet at all.Final Project Report DE-FC07-97ID13578 3 Laser ultrasonic methods are also able to determine flexural rigidity and thereby bending stiffness directly, which earlier on-line ultrasonic methods for determining planar modulus of elasticity, could only infer indirectly. Flexural rigidity is the property that determines end-product rigidity and is of great importance to a wide variety of paper grades. Laser ultrasonics could also provide single-sensor in-plane and out-of-plane characterization and give the first on-line gauge of stiffness orientation, being easily reconfigurable while in operation to measure along any planar orientation.This project represents the combined efforts of two organizations with complementary experiences in paper physics and laser ultrasonics. LNBL is expert in the art of laser acoustic wave generation and has made good progress in developing instrumentation and techniques for inducing optimally large ultrasonic excitations in paper while avoiding damage to the sheet. They developed a scanning-mirror, Mach-Zehnder interferometer that works well at high speeds on a web-simulator. IPST at GeorgiaTech contributes paper physics expertise and close relations with the paper industry, has provided working experience in the construction of unique laboratory ultrasonic systems for paper, and experience with the design and implementation upon a host ABB Smart Platform scanning system. The two organizations continue to work together to improve these technologies for web measurements. Our industrial partner is ABB and they are contributing web stabilization technology, advice for design of on-line instrument, environmental specifications for on-line instruments, and various software for interfacing our sensor with the existing sensors on their scanning platform. Rick Russo from LBNL. The first time the proposal was not accepted and P. Brodeur decided to re-propose it without the involvement from LBNL. Rick Russo proposed a separate project on the same topic on his side. Both ...

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“…Plasma formation and consequent material ablation on solid surfaces has been found to give the highest light to sound conversion efficiency, if compared to thermoelastic processes [6]. Dielectric breakdown above a material surface in air has been found to be a useable source of ultrasound in a solid [7]. Claimed generation efficiencies range up to 30% in this regime [8].…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Testing Method for Air Ultrasonic Transducers Using a Photoacoustic Pulse Source

Oksanen

Hietanen

Luukkala

1995

Review of Progress in Quantitative Nondestructive Evaluation

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Ultrasonic generation with a pulsed TEA CO₂laser

Cited by 22 publications

References 11 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

Final Technical Report of project: "Contactless Real-Time Monitoring of Paper Mechanical Behavior During Papermaking"

Testing Method for Air Ultrasonic Transducers Using a Photoacoustic Pulse Source

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Ultrasonic generation with a pulsed TEA CO2laser

Cited by 22 publications

References 11 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

Final Technical Report of project: "Contactless Real-Time Monitoring of Paper Mechanical Behavior During Papermaking"

Testing Method for Air Ultrasonic Transducers Using a Photoacoustic Pulse Source

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Product

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Ultrasonic generation with a pulsed TEA CO₂laser