Pulsed-laser excited thermal lens spectroscopy with sample-fluid heat coupling

Astrath, N. G. C.; Malacarne, L. C.; Lukasievicz, Gustavo V. B.; Belançon, Marcos Paulo; Baesso, Mauro Luciano; Joshi, Prakash; Bialkowski, Stephen E.

doi:10.1063/1.3372726

Cited by 10 publications

(6 citation statements)

References 19 publications

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“…The two beams have no delay when they reach PBS1 except for the acoustic vibration induced phase difference, and they finally interfere after being converted to circular polarization states with a fiber polarization controller. The beams are split one last time with PBS3 to dramatically reduce interferometer noise and make the system insensitive to thermal lens [25] effects induced by the pumping laser. When the polarization controller (PBS3 in the drawing) is tuned to act as a perfect quarter wave plate, the two beams have opposite signs in the interference term at the two inputs of a balanced photodetector.…”

Section: Methodsmentioning

confidence: 99%

NDT of fiber-reinforced composites with a new fiber-optic pump–probe laser-ultrasound system

et al. 2014

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Laser-ultrasonics is an attractive and powerful tool for the non-destructive testing and evaluation (NDT&E) of composite materials. Current systems for non-contact detection of ultrasound have relatively low sensitivity compared to contact peizotransducers. They are also expensive, difficult to adjust, and strongly influenced by environmental noise. Moreover, laser-ultrasound (LU) systems typically launch only about 50 firings per second, much slower than the kHz level pulse repetition rate of conventional systems. As demonstrated here, most of these drawbacks can be eliminated by combining a new generation of compact, inexpensive, high repetition rate nanosecond fiber lasers with new developments in fiber telecommunication optics and an optimally designed balanced probe beam detector. In particular, a modified fiber-optic balanced Sagnac interferometer is presented as part of a LU pump–probe system for NDT&E of aircraft composites. The performance of the all-optical system is demonstrated for a number of composite samples with different types and locations of inclusions.

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Section: Methodsmentioning

confidence: 99%

NDT of fiber-reinforced composites with a new fiber-optic pump–probe laser-ultrasound system

et al. 2014

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“…The latter is a good approximation when air is the surrounding fluid. 19 The initial temperature change is assumed to be zero, T ( r , z, 0 ) = 0. Here Q 0 = 2 E 0 A e (1 – R )φ/ c ρπω 2 0 e , E 0 is the pulse laser energy, A e is the optical absorption coefficient at the excitation beam wavelength, R is the surface reflectivity, and ω 0 e is the electric field beam waist radius parameter.…”

Section: Theorymentioning

confidence: 99%

Pulsed-Laser Time-Resolved Thermal Mirror Technique in Low-Absorbance Homogeneous Linear Elastic Materials

et al. 2013

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A theoretical model for a time-resolved photothermal mirror technique using pulsed-laser excitation was developed for low absorption samples. Analytical solutions to the temperature and thermoelastic deformation equations are found for three characteristic pulse profiles and are compared to finite element analysis methods results for finite samples. An analytical expression for the intensity of the center of a continuous probe laser at the detector plane is derived using the Fresnel diffraction theory, which allows modeling of experimental results. Experiments are performed in optical glasses, and the models are fitted to the data. The parameters of the fit are in good agreement with previous literature data for absorption, thermal diffusion, and thermal expansion of the materials tested. The combined modeling and experimental techniques are shown to be useful for quantitative determination of the physical properties of low absorption homogeneous linear elastic material samples.

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“…Recently, we have shown that TL and TM spectroscopies can be used to study the sample-fluid heat-coupling problem in the case of low-optical-absorbing material by using continuous 12 or pulsed excitation. 13 Similar to the mirage method, the TM technique can be used to (1) determine thermal and optical proprieties of transparent fluids by using a reference solid material as absorber medium, and (2) determine thermal and mechanics proprieties of solid material, knowing the transparent fluids.…”

Section: Introductionmentioning

confidence: 99%

A Theoretical and Experimental Study of Time-Resolved Thermal Mirror with Non-Absorbing Heat-Coupling Fluids

et al. 2012

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A theoretical and experimental study taking sample-fluid heat coupling into account in time-resolved photothermal mirror experiments is presented. Thermoelastic equations were solved to obtain a semi-analytical solution to the phase shift induced by the sample and the surrounding fluid. The solution was used to model the thermal mirror effects and found to be in excellent agreement with the finite element method analysis and experiment. Heat transferred to the air-coupling fluid did not introduce important effects in the phase shift when compared with the solution obtained, without considering heat flux. However, when using water as the fluid, heat coupling led to a significant effect in fluid phase shift. Experimental results using stainless steel in air and water were used to demonstrate the potentiality of the thermal mirror technique to determine the thermal properties of both the sample and the fluid.

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Pulsed-laser excited thermal lens spectroscopy with sample-fluid heat coupling

Cited by 10 publications

References 19 publications

NDT of fiber-reinforced composites with a new fiber-optic pump–probe laser-ultrasound system

NDT of fiber-reinforced composites with a new fiber-optic pump–probe laser-ultrasound system

Pulsed-Laser Time-Resolved Thermal Mirror Technique in Low-Absorbance Homogeneous Linear Elastic Materials

A Theoretical and Experimental Study of Time-Resolved Thermal Mirror with Non-Absorbing Heat-Coupling Fluids

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