Abnormal photon absorption behavior in melanin detected by photothermal lensing due to simultaneous irradiation with multiple laser wavelengths

Han, Yue; Rosenshein, Joseph S.; Wu, Z. L.; Wen, Ye; Thomsen, J. Marshall; Zhao, Qiang

doi:10.1117/1.1339202

Cited by 5 publications

(2 citation statements)

References 21 publications

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“…Thus, our experiments demonstrated that the presented model allowed for obtaining reasonable physical parameters. A previous study showed a different model for nonlinear absorption by melanin that included a triplet state 43 . Future work should comparatively evaluate these two models by measuring the energy relaxation processes of melanin excited by laser pulses at a wavelength of 532 nm.…”

Section: Discussionmentioning

confidence: 99%

“…A previous study showed a different model for nonlinear absorption by melanin that included a triplet state. 43 Future work should comparatively evaluate these two models by measuring the energy relaxation processes of melanin excited by laser pulses at a wavelength of 532 nm. The time scale of energy relaxation processes depends on the surrounding medium (see Table 1).…”

Section: Discussionmentioning

confidence: 99%

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Nonlinear absorption‐based analysis of energy deposition in melanosomes for 532‐nm short‐pulsed laser skin treatment

et al. 2023

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Background and Objectives: The clinical use of 532-nm short-pulsed lasers has provided effective treatment of epidermal pigmented lesions. However, the detection of significant differences in treatment effects between picosecond and nanosecond lasers has still varied among clinical studies. For robust evaluation of the differences based on the treatment mechanism, this study presents a nonlinear absorption-based analysis of energy deposition in melanosomes for 532-nm shortpulsed laser treatment. Study Design/Materials and Methods: Nonlinear absorption by melanin is modeled based on sequential two-photon absorption. Absorption cross-sections and nonradiative lifetimes of melanin, which are necessary for the nonlinear absorption-based analysis, are determined from transmittance measurement. Using the model and parameters, energy deposition in melanosomes was calculated with varying fluence and pulse width settings, including actual clinical parameters.Results: The energy deposition in melanosomes increased with shorter laser pulses, and subnanosecond laser pulses were found to be most efficient. The comparison of energy deposition calculated using clinical parameters demonstrated the differences in treatment effects between picosecond and nanosecond lasers reported in clinical studies. Conclusion:The nonlinear absorption-based analysis provides quantitative evidence for the safety and efficacy evaluation of short-pulsed laser treatments, which may lead to the establishment of numerical indices for determining treatment conditions. Future studies considering the effects of the surrounding tissue on energy deposition in melanosomes will be needed.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Nonlinear absorption‐based analysis of energy deposition in melanosomes for 532‐nm short‐pulsed laser skin treatment

et al. 2023

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An analytical model for finite radius dual-beam mode-mismatched thermal lens spectroscopy

Sabaeian

Nadgaran

2013

Journal of Applied Physics

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In this work, a new model for dual-beam mode-mismatch thermal lens spectroscopy is presented. The model was based on a new analytical solution of time-dependent heat equation for finite radius cylindrical samples exposed to TEM00 excitation laser beams. The Fresnel diffraction integration method was used to calculate time-dependent on-axis probe beam intensity. All aberrations in thermal lens were taken into account. The model yields accurate values for absorption coefficient and thermal diffusivity of methylene blue aqueous solution. Furthermore, the optimized mode-mismatched version of this model when applied to pure water as a very low absorbent yields its absorption coefficient and thermal diffusivity values close to literature data. In contrast to traditional model, this model does not need to omit any term in its theory to fit the experimental data.

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Laser photothermal spectroscopy of light-induced absorption

Skvortsov¹

2013

Quantum Electron.

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Abnormal photon absorption behavior in melanin detected by photothermal lensing due to simultaneous irradiation with multiple laser wavelengths

Cited by 5 publications

References 21 publications

Nonlinear absorption‐based analysis of energy deposition in melanosomes for 532‐nm short‐pulsed laser skin treatment

Nonlinear absorption‐based analysis of energy deposition in melanosomes for 532‐nm short‐pulsed laser skin treatment

An analytical model for finite radius dual-beam mode-mismatched thermal lens spectroscopy

Laser photothermal spectroscopy of light-induced absorption

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