The Theory of Powerful Laser Light Propagation in a Material Medium

Results of novel experiments with laser-heated capillary targets are presented. In these experiments the interior of gold capillaries having a 200- or 700-μm inner diameter and a 2–12-mm length was axially irradiated by injection of the laser energy through one of the end openings. A frequency-doubled Nd:glass laser (λ = 0.53 μm) was employed, delivering 8-J energy in 3 ns. The experiments showed no significant backreflection of laser light. Depending on the capillary diameter and length, most of the laser energy is either transmitted or absorbed inside the capillary. The transmission of laser light was measured as a function of capillary length and found to be in good agreement with the predictions of a simple theoretical model. Two extreme cases could be identified. Capillaries with a 700-μm diameter show uninhibited laser light propagation due to multireflections off the inner wall. In contrast, at the entrance of capillaries with a 200-μm inner diameter a plasma plug forms that absorbs most of the laser energy. In both cases significant energy transport was observed to occur in the axial direction. A stable and strongly radiating plasma column is formed along the capillary axis by the collision of the radially imploding plasma. During the collision, part of the hydrodynamic energy of the plasma is converted into radiative energy. In a special case-a lower limit of ≊7% could be inferred for the conversion efficiency from laser light into X-ray radiation emitted from the rear opening of the capillary.

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Monte-Carlo simulation of Doppler shift for laser light propagation in human teeth

10.1117/12.301084 ◽

1998 ◽

Author(s):

Pavel Y. Starukhin ◽

Natalia A. Kharish ◽

Anatoliy Karpovitch ◽

Alexander V. Lepilin ◽

Sergey S. Ulyanov ◽

...

Keyword(s):

Monte Carlo Simulation ◽

Monte Carlo ◽

Doppler Shift ◽

Light Propagation ◽

Laser Light ◽

Human Teeth

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Laser Light Propagation And Parametric Coupling in Dense Media

EQEC 96 1996 European Quantum Electronic Conference EQEC-96 ◽

10.1109/eqec.1996.561632 ◽

1996 ◽

Author(s):

W. Chalupczak ◽

W. Gawlik ◽

B. Samson ◽

J. Zachorowski

Keyword(s):

Light Propagation ◽

Laser Light ◽

Dense Media ◽

Parametric Coupling

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Dose Analysis of Photobiomodulation Therapy in Stomatology

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2020/8145616 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Chuan-Tsung Su ◽

Chung-Ming Chen ◽

Chun-Cheng Chen ◽

Jih-Huah Wu

Keyword(s):

Power Density ◽

Quantitative Measurement ◽

Light Propagation ◽

Laser Light ◽

Target Tissue ◽

The Real ◽

Quantitative Calculation ◽

Attached Gingiva ◽

Simulation Results ◽

Acupoint Stimulation

The penetration depth and the power density of photobiomodulation (PBM) in human tissue under real conditions remain unclear to date. A novel quantitative measurement method was proposed in this study. This study aimed to design a noninvasive measurement system for the quantitative calculation of PBM dose on the attached gingiva. A flexible facial fixture appliance (FFFA) and nine piece detectors were mounted on the retainer to detect the real dose of 660 and 830 nm lasers on the attached gingiva. In addition, the angular distribution of light scattering and the light propagation in the biotissue were obtained. Two cases (a female and a male) are presented in this study. Experimental results demonstrated that the real power density of laser in the target tissue can be measured exactly after the laser light penetrates the orbicularis oris. Simulation results match with real conditions. Conversely, slight differences in power density are observed in the tissue radiated with collimated and uncollimated laser. The proposed method can be used to calculate the real dose in the target tissue for stomatology and deep acupoint stimulation.

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