Determination of optical characteristics of biological tissues by temporal distribution of an ultrashort laser pulse passed through homogeneous scattering layer

Tereshchenko, S. A.; Данилов, А. А.; Dolgushin, S. A.; Titenok, S. A.

doi:10.1134/s0030400x11040229

Cited by 5 publications

(4 citation statements)

References 5 publications

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“…Femtosecond laser pulse shaping in the time domain is a new fabrication method that can improve and control ultrafast laser fabrication [49][50][51][52][53]. During femtosecond laser fabrication, most photon energy is initially absorbed by electrons.…”

Section: Femtosecond Fabrication By Laser Pulse Shaping In Time Domainmentioning

confidence: 99%

“…A pulse shaper is a commercially available device that combines Fourier optics and femtosecond laser ( Fig. 17) and is used to generate pulse trains to realize Optical Code Division Multiple Access systems [49], as well as for chemical and biological reaction triggering and monitoring [51]. This device utilizes the Fourier optics principle to fine tune highorder dispersion compensation, perform time-frequency transform of femtosecond laser pulses, obtain pulse spectra with different time distributions, and generate transformlimited few-cycle optical pulses to produce and control pulse trains [52].…”

Section: Laser Pulse Shaping Using a Pulse Shapermentioning

confidence: 99%

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Femtosecond Laser Micro/Nano-manufacturing: Theories, Measurements, Methods, and Applications

et al. 2020

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Femtosecond laser fabrication has grown to be a major method of extreme manufacturing because of the extreme energy density and spatial and temporal scales of femtosecond lasers. The physical effects and the mechanism of interaction between femtosecond lasers and materials are distinct from those in traditional processes. The nonlinear and nonequilibrium effects of the interaction have given rise to new concepts, principles, and methods, such as femtosecond pulse durations are shorter than many physical/chemical characteristic times, which permits manipulating, adjusting, or interfering with electron dynamics. These new concepts and methods have broad application prospects in micro/nanofabrication, chemical synthesis, material processing, quantum control, and other related fields. This review discusses the cutting-edge theories, methods, measurements, and applications of femtosecond lasers to micro/nano-manufacturing. The key to future development of femtosecond laser manufacturing lies in revealing its fabrication mechanism from the electronic level and precisely regulating the electronic dynamics.

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Section: Femtosecond Fabrication By Laser Pulse Shaping In Time Domainmentioning

confidence: 99%

Section: Laser Pulse Shaping Using a Pulse Shapermentioning

confidence: 99%

Femtosecond Laser Micro/Nano-manufacturing: Theories, Measurements, Methods, and Applications

et al. 2020

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“…1). Optical SSM parameters are derived from experimental temporal dis tribution and models taken from the literature [8].…”

Section: S a Tereshchenko* And S A Titenokmentioning

confidence: 99%

“…This diversity is due to difference in the assumptions of different models [8]. Comparative assess ment of the models is required in controlled SSM condi tions.…”

mentioning

confidence: 99%

Comparative Study of Diffusion and Axial Models of Radiation Passing through a Biological Scattering Layer Based on the Monte Carlo Method

Tereshchenko

Titenok

2012

Biomed Eng

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The Monte Carlo method (MCM) is used for math ematical simulation of many complicated processes [1]. Propagation of optical radiation through strongly scatter ing medium (SSM) is such a problem [2,3]. In biomedical research, SSM represents biological tissues. Near IR lasers should be used for testing such objects. The near IR range corresponds to a so called transparency window [4].The interaction of IR radiation with biological tis sues is characterized by two processes: absorption and scattering. The probability of scattering is 1 2 orders of magnitude larger than the probability of absorption. SSM is characterized by extinction coefficient and scattering indicatrix. It is difficult to monitor extinction coefficient and scattering indicatrix simultaneously. Thus, scattering coefficient is used instead of scattering indicatrix.Ultrashort laser pulses together with photon count ing are used in experiments. The propagation of pulsed radiation through SSM is described using the transient equation (TE). The TE contains optical parameters of the medium as coefficients for photon flux density. Because TE has no analytical solution, a numerical method with additional assumptions is used. Two models are most fre quently used: the diffusion [5, 6] and axial models [7].Numerical diversity of SSM optical parameters is a serious problem. This diversity is due to difference in the assumptions of different models [8]. Comparative assess ment of the models is required in controlled SSM condi tions. The MCM provides such controlled SSM condi tions.The MCM is based on the trajectory of individual photons with given optical parameters of the SSM. In the case of ultrashort laser pulses, the MCM gives temporal distribution of detected photons. Comparison of various models (MCM and other models of radiation propaga tion in SSM) allows the capacity of each model to be evaluated in terms of temporal distribution of optical parameters in individual samples. TheoryThe photon propagation trajectory through SSM is determined by scattering events. In isotropic SSM the scattering indicatrix μ s (Ω → Ω → ') determines the photon scat tering probability in direction Ω → and solid angle dΩ' near the trajectory Ω → ' during passage of distance dl:Absorption coefficient μ a , scattering coefficient μ s , and extinction coefficient μ = μ a + μ s are macroscopic optical parameters of a SSM. The anisotropy factor g is mean cosine of scattering angle: 211 0006 3398/12/4506 0211 A comparative study of the diffusion and axial models (non stationary axial model, NAM; comprehensive diffu sion model, CDM; and revised diffusion model, RDM) of radiation passing through a biological scattering layer based on the Monte Carlo method is described. NAM gives scattering coefficient close to reduced scattering coef ficient rather than to complete scattering coefficient. It is concluded that RDM is superior to CDM.

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An imperfection of time-dependent diffusion models for a determination of scattering medium optical properties

Tereshchenko

Dolgushin

Titenok

2013

Optics Communications

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Determination of optical characteristics of biological tissues by temporal distribution of an ultrashort laser pulse passed through homogeneous scattering layer

Cited by 5 publications

References 5 publications

Femtosecond Laser Micro/Nano-manufacturing: Theories, Measurements, Methods, and Applications

Femtosecond Laser Micro/Nano-manufacturing: Theories, Measurements, Methods, and Applications

Comparative Study of Diffusion and Axial Models of Radiation Passing through a Biological Scattering Layer Based on the Monte Carlo Method

An imperfection of time-dependent diffusion models for a determination of scattering medium optical properties

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