Propagation of Focused and Multibeam Laser Energy in Biological Tissue

2000 ◽  
Vol 122 (5) ◽  
pp. 534-540 ◽  
Author(s):  
Alex J. Fowler ◽  
M. Pinar Menguc
Keyword(s):  
Biological Tissue ◽  
Laser Energy ◽  
Laser System ◽  
Scattering Coefficient ◽  
Tissue Properties ◽  
Energy Delivery ◽  
Beam Laser ◽  
Primary Determinant ◽  
Focused Beam ◽  
Reduced Scattering Coefficient

The results of a Monte Carlo simulation of laser beam propagation in turbid media are presented. The study was performed to determine whether using a focused beam or multiple beams instead of a single collimated beam could improve subsurface laser energy delivery in biological tissue. A parametric study was carried out to determine both the laser fluence at a target depth and the ratio of fluence at the target over surface fluence as a function of tissue properties and the mode of energy delivery. It was found that the reduced scattering coefficient was the primary determinant as to whether multibeam or focused beam delivery could be effective. A focused beam was found to be extremely effective in increasing fluence at the target if the dimensionless reduced scattering coefficient was less than 2. The delivered fluence, however, was found to be extremely sensitive to tissue properties. A five-beam laser system was found to be less effective at increasing fluence at the target than a focused beam; but the fluence delivered by a five-beam system was far less sensitive to tissue properties, thereby making accurate dosimetry more feasible. [S0148-0731(00)01205-X]

scholarly journals Determination of reduced scattering coefficient of biological tissue from a needle-like probe

2005 ◽  
Vol 13 (13) ◽  
pp. 4828 ◽  
Author(s):  
Maureen Johns ◽  
Cole A. Giller ◽  
Dwight C. German ◽  
Hanli Liu
Keyword(s):  
Biological Tissue ◽  
Scattering Coefficient ◽  
Reduced Scattering Coefficient

Investigations of Femtosecond-Nanosecond Dual-Beam Laser Ablation of Dielectrics

2009 ◽  
Author(s):  
Z. H. Rao ◽  
C. H. Lin ◽  
L. Jiang ◽  
W. J. Tsai ◽  
P. H. Wu ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Laser Pulse ◽  
Laser Energy ◽  
Removal Rate ◽  
Laser System ◽  
Domain Model ◽  
Beam Laser ◽  
Temporal Domain ◽  
Dual Beam ◽  
Fs Laser

A multi-scale (in temporal domain) model was developed to study the ablation of dielectrics using a femtosecond (fs)-nanosecond (ns) dual-beam laser system. The model is an integration of the plasma model and improved two-temperature model for the fs laser ablation, and Fourier’s law for the ns laser ablation. The model is used to investigate the ablation for dielectrics when a fs pulse is shot at the peak of a ns pulse. It is found that the fs laser pulse can result in the increase of absorption of the ns laser energy, leading to a much higher material removal rate as compared to fs laser ablation alone or ns laser ablation alone. The enhancement of ns laser energy absorption is caused by the increased electron density and the formation of a tiny crater in the material created by the fs laser pulse. The corresponding experiment using a Ti:Sapphire fs laser (Legend-F, Coherent) and a Nd:YAG ns UV laser (Avia-X, Coherent) was also conducted and the results are consistent with the modeling predictions.

Spectral Analysis of X-Rays from Laser-Induced Plasmas†

1974 ◽  
Vol 18 ◽  
pp. 159-168 ◽  
Author(s):  
J. F. Cuderman ◽  
K. M. Glibert
Keyword(s):  
Spectral Analysis ◽  
Total Energy ◽  
Spectral Range ◽  
Laser Energy ◽  
Laser System ◽  
X Rays ◽  
Laser Interaction ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
Beam Laser

AbstractLaser interaction experiments have been conducted on Sandia Laboratories' four-beam laser system. In these experiments, pulses of 1.06 μm light of up to 50 J each were focused in a tetrahedral geometry onto CD2 microspheres. A 22-channel x-ray spectrometer which utilises silicon diodes with appropriate K-edge prefilters was used for x-ray measurements. Typically, bremsstrahlung-recombination spectra were observed in the photon regime below about 5 keV. The electron temperatures for this part of the spectrum ranged from a few hundred eV to 1 keV with up to 15 percent of the total laser energy converted to x-rays. Less than one percent of the total energy emitted as x-rays appeared in the spectral range above 5 keV.

Characterization of the Asphaltene Onset Region by Focused-Beam Laser Reflectance: A Tool for Additives Screening†

2009 ◽  
Vol 23 (3) ◽  
pp. 1155-1161 ◽  
Author(s):  
Javier Marugán ◽  
José A. Calles ◽  
Javier Dufour ◽  
Raúl Giménez-Aguirre ◽  
José Luis Peña ◽  
...  
Keyword(s):  
Beam Laser ◽  
Laser Reflectance ◽  
Focused Beam

SIMULATION OF SINGLE CHANNEL BIOLOGICAL TISSUE SPECTROSCOPY USING COMSOL MULTIPHYSICS

2015 ◽  
Vol 77 (28) ◽  
Author(s):  
Azmi Abou Basaif ◽  
Nashrul Fazli Mohd Nasir ◽  
Zulkarnay Zakaria ◽  
Ibrahim Balkhis ◽  
Shazwani Sarkawi ◽  
...  
Keyword(s):  
Magnetic Induction ◽  
Biological Tissue ◽  
Single Channel ◽  
Medical Condition ◽  
Biological Tissues ◽  
Comsol Multiphysics ◽  
Accurate Information ◽  
Tissue Properties ◽  
Biological Soft Tissue

The enhanced ability to detect accurate location and measure the depth of a   metal inside a biological tissue is very useful in the assessment of medical condition and treatment. This manuscript proposed a solution via the measurement of the tissue properties using magnetic induction spectroscopy (MIS) method to describe the characterization of biological soft tissue. The objective of this study is to explore the viability of locating embedded metal inside a biological tissue by measuring the differences the biological tissue electrical properties using principle of Magnetic Induction Spectroscopy (MIS). Simulation is done using COMSOL Multiphysics software for accurate information on the involved parameters for both metal and biological tissues. Simulation has confirmed that MIS capable of detecting and locate embedded metal inside a biological tissue.

scholarly journals A Personal Reflection of Greenlight 532 nm Laser for BPH Treatment

2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
Bilal Chughtai ◽  
Claire Dunphy ◽  
Alexis Te
Keyword(s):  
Surgical Therapy ◽  
Laser Energy ◽  
Laser System ◽  
Prostatic Hyperplasia ◽  
First Line ◽  
Technological Advances ◽  
Urinary Tract Symptoms ◽  
Bothersome Symptom ◽  
532 Nm ◽  
Lower Urinary

Lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia are a bothersome symptom set that affect approximately one in every four males above the age of 50. First line treatment is typically medication, but when medications fail surgical therapy is the next option. Technological advances have made surgical therapy safer and more effective. One area that our group has particular interest and focus in is the application of the 532 nm laser in surgical therapy. The high power 532 nm laser is used to remove obstructive prostatic tissue and the laser energy is selectively absorbed by hemoglobin in the prostate tissue, resulting in effective tissue vaporization and removal. We review our experience with Greenlight laser system and its evolution from the original 60-watt laser to the most recent 180-watt Greenlight system with MoXy fiber.

scholarly journals Determination of the imploded mass in laser-imploded shell targets

1986 ◽  
Vol 4 (3-4) ◽  
pp. 507-514 ◽  
Author(s):  
S. Denus ◽  
J. Farny ◽  
M. Grudzień ◽  
W. Mróz ◽  
J. Wołowski ◽  
...  
Keyword(s):  
Neutral Atom ◽  
Neutral Particle ◽  
Laser System ◽  
Semiconductor Diode ◽  
Velocity Spectrum ◽  
Particle Detector ◽  
Beam Laser ◽  
Atom Flux ◽  
Time Of Flight Method

A new method of experimental measurement of the imploded mass of laser-imploded shell targets is proposed. This method is based on simultaneous measurements of the velocity spectrum of the neutral atom flux emitted from the imploded part of the target, and the total energy carried by them. A semiconductor diode with a shallowly located p – n junction was used as the low energy neutral particle detector. By means of the time of flight method neutral atom fluxes with velocities υ ∼ (0·6 − 1·8) × 107cm/s were registered in experiments carried out on the 6-beam laser system “Delfin”.

Sign in / Sign up

Export Citation Format

Share Document