Photoacoustic signal saturation and optical limiting in C&lt;sub&gt;70&lt;/sub&gt;-toluene solution

Issac, R. C.; Harilal, S. S.; Varier, Geetha K.; Bindhu, C. V.; Nampoori, V. P. N.; Vallabhan, C. P. G.

doi:10.1117/1.601205

Cited by 4 publications

(1 citation statement)

References 27 publications

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“…7-10 Photothermal effects are generated by deposition of heat in a sample due to nonradiative deexcitation following absorption of radiation. 11,12 Laser based photothermal methods such as the photoacoustic effect 7,8 for the determination of thermal diffusivity of materials have become very popular due to the many advantages offered by such techniques.…”

Section: Introductionmentioning

confidence: 99%

Thermal diffusivity measurements in organic liquids using transient thermal lens calorimetry

Bindhu

1998

Opt. Eng

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Thermal diffusivity measurements are carried out in certain organic liquids using the pulsed dual beam thermal lens technique. The 532 nm pulses from a frequency doubled Q-switched Nd:YAG laser are used as the heating source and an intensity stabilized He-Ne laser serves as the probe beam. Experimental determination of the characteristic time constant of the transient thermal lens signal is verified theoretically. Measured thermal diffusivity values are in excellent agreement with literature values.

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Section: Introductionmentioning

confidence: 99%

Thermal diffusivity measurements in organic liquids using transient thermal lens calorimetry

Bindhu

1998

Opt. Eng

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Picosecond absorption relaxation measured with nanosecond laser photoacoustics

Danielli

Favazza

Maslov

et al. 2010

Applied Physics Letters

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Picosecond absorption relaxation-central to many disciplines-is typically measured by ultrafast ͑femtosecond or picosecond͒ pump-probe techniques, which however are restricted to optically thin and weakly scattering materials or require artificial sample preparation. Here, we developed a reflection-mode relaxation photoacoustic microscope based on a nanosecond laser and measured picosecond absorption relaxation times. The relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, were measured at 576 nm. The added advantages in dispersion susceptibility, laser-wavelength availability, reflection sensing, and expense foster the study of natural-including strongly scattering and nonfluorescent-materials. © 2010 American Institute of Physics. ͓doi:10.1063/1.3500820͔Picosecond absorption relaxation is central to many optical phenomena in physics, chemistry, biology, and medicine-such as absorption saturation, 1-3 photosynthesis, 4 and photolysis. [5][6][7] Typically, relaxation times are studied via an ultrafast ͑femtosecond or picosecond͒ pump-probe technique by measuring either fluorescence in a reflection configuration or absorption in a transmission configuration. 8,9 In the reflection-based approach, the molecules are excited by a laser pulse through the transition ͉0͘ → ͉i͘. A probe pulse with a variable delay time relative to the pump pulse monitors the time evolution of the population density N i ͑t͒. 8 When applied to molecules with low fluorescence quantum yield, this approach is noisy. In the transmission-based approach, the relaxation time is extracted by measuring pump-induced changes in probe-beam transmittivity ⌬T = T͑I p ͒ − T͑0͒, where T͑I p ͒ and T͑0͒ are the probe beam transmittivities with and without a pump of intensity I p . 9 In both approaches, the time resolution is limited by the pulse width of both the pump and the probe pulses. Hence, not only is an expensive picosecond or femtosecond laser required, but also the detection is susceptible to pulse broadening in dispersive media. Alternatively, intensity correlation of nanosecond laser pulses can be used. 10,11 Working in transmission mode, this technique is not suitable for optically thick media. All of the current techniques are limited to optically thin and weakly scattering materials or require artificial sample preparation.Photoacoustic microscopy and photoacoustic computed tomography, usually based on nanosecond laser excitation, are effective functional and molecular imaging tools in vivo. In the photoacoustic phenomenon, light is absorbed by a material and converted to heat. The subsequent thermoelastic expansion generates a detectable acoustic wave. 12 Photoacoustic sensing presents an exquisite sensitivity due to its inherent background-free nature. Its relative sensitivity to absorption reaches the theoretical limit of 100%, by far the highest among all optical imaging modalities. Most quantitative photoacoustic studies have assumed a linear dependence between ...

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A Novel Mobile Audio Bandwidth Extension Algorithm Oriented 3G Communication

Zhang

2010

2010 International Conference on Multimedia Technology

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Photoacoustic signal saturation and optical limiting in C<sub>70</sub>-toluene solution

Cited by 4 publications

References 27 publications

Thermal diffusivity measurements in organic liquids using transient thermal lens calorimetry

Thermal diffusivity measurements in organic liquids using transient thermal lens calorimetry

Picosecond absorption relaxation measured with nanosecond laser photoacoustics

A Novel Mobile Audio Bandwidth Extension Algorithm Oriented 3G Communication

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