scholarly journals Time Resolved Photon Fluencies for Different Input Angle Sources

2021 ◽  
Author(s):  
huseyin ozgur kazanci ◽  
Kiichi Niitsu
Keyword(s):  
Coordinate System ◽  
Pulsed Laser ◽  
Forward Model ◽  
Simulation Program ◽  
Laser Source ◽  
Simulation Environment ◽  
Time Resolved ◽  
Tissue Surface ◽  
Photon Fluence ◽  
Laser Sources

Abstract The variation of photon fluence distributions [photon/cm2.s] for different input angle laser sources was shown by researchers experimentally [1]. According to this philosophy, different input angle source and detector photon entrance from tissue surface into imaging media have different photon fluence distributions for a specific tissue type. In this study, different input angle simulations were used for pulsed laser photons which uses time resolved (TR) Monte Carlo (MC) photon-tissue interaction simulation program to prove the philosophy in TR run mode. TR run mode MC simulation program trmc.c [2] was modified and used to generate TR photon counts inside the homogenous simulation environment. It has homogeneous tissue optical properties, absorption μa = 0.1 cm-1, scattering μs = 100 cm-1, and anisotropy g = 0.90 coefficients. Multi-input angle philosophy was first demonstrated by the researchers [1]. It was defined and experimentally proven. Photon fluencies which are forward model weight matrix coefficients differences were successfully shown for TR laser as a general procedure. In this study, differences were drawn for seven different input angle sources with pulsed laser photons. The proof-of-concept philosophy was shown successfully. The purpose of the use of pulsed laser is to show the righteousness of the philosophy in TR run mode, since the TR diffuse optical tomography (TRDOT) device would be made as a biomedical optic imaging (BOI) device. Cylindrical radial coordinate system which was defined in trmc.c [2] in earlier was used, the code was modified, and photon fluencies were generated based on the different input angle laser photons. Cylindrical coordinate system has 1 cm and 36-element radial r, and depth z grids. 100.000 photons were sent from pencil beam tissue surface point. Photons would be thought as group of ultra-narrow band pulsed laser photons. The main purpose of showing photon fluencies for different laser source input angles were succeeded and image reconstruction procedure was also applied. Ten time series were used which are [4, 8, 12, 16, 22, 26, 30, 38, 46, 52] picoseconds (ps). Different input angle photon fluence distribution figures were drawn. These are 0º, 15º, 30º, 45º, 60º, 75º, 90º. Photon fluence differences were also drawn and observed for different input angle laser sources. Forward model problem different input angle laser source and detector transfer functions were also drawn. Finally inlusion was embedded inside the homogenous simulation environment and images were reconstructed for both scenarios and localization error (LE), and concentration error (CE) was calculated for both scenarions and compared with each other.

Software Enhanced Time Resolved Laser Assisted Device Alteration with a Non-Pulsed Laser Source

2009 ◽  
Author(s):  
Kent Erington ◽  
John Asquith ◽  
Dan Bodoh
Keyword(s):  
Temporal Resolution ◽  
Laser Scanning ◽  
Pulsed Laser ◽  
Laser Source ◽  
Scanning Microscope ◽  
Time Resolved ◽  
Laser Scanning Microscope ◽  
Timing Information ◽  
Custom Software

Abstract We describe a technique that is used to obtain timing information from laser assisted device alteration (LADA). The technique uses a non-pulsed laser scanning microscope to obtain timing information with a temporal resolution on the order of microseconds. Custom software is used to extract the timing information from the LADA images.

scholarly journals Increasing of Pulsed Laser Source Peak Power by Use of Ring Fiber-Optic Delay Line

2019 ◽  
Vol 10 (2) ◽  
pp. 151-159
Author(s):  
V. A. Alekseev ◽  
M. R. Zaripov ◽  
A. S. Perminov ◽  
E. A. Sitnikova ◽  
V. P. Usol’tsev ◽  
...  
Keyword(s):  
Peak Power ◽  
Delay Line ◽  
Fiber Optic ◽  
Optical Switch ◽  
Pulsed Laser ◽  
Laser Source ◽  
Energy Effectiveness ◽  
Laser Systems ◽  
Laser Sources ◽  
Optical Combiner

At the present time, developing of autonomous laser systems requires increasing of the output power of the laser sources used in composition of those systems and at the same time reducing of the energy usage in the system. The possibility of increasing output peak power of pulsed laser sources by using the method of synchronous non-coherent beam combining in ring fiber-optic delay line is considered by authors. Objective of this work was estimating energy effectiveness of laser systems, which based on this method.General constructing method of the laser pulsed laser source with ring fiber delay line is considered, its block diagram and the general operating principle of similar systems are presented. Two versions of laser systems based on the described method of beam combining are presented: using an optical combiner and an optical switch; using fiber welding instead of a combiner and an optical switch. The graphical dependence of the energy effectiveness on the number of circulations in ring fiber-optic delay line is obtained for both versions of laser systems.As a result of the analysis of the considered devices operation, it was shown that considered systems allow to obtain increasing the peak power of a laser pulse without increasing the power supply, also the system, that use welded fi instead of the optical combiner, has greater effi than system with optical combiner.

scholarly journals Smoothing additive manufactured parts using ns-pulsed laser radiation

2021 ◽  
Author(s):  
Florian Kuisat ◽  
Fernando Lasagni ◽  
Andrés Fabián Lasagni
Keyword(s):  
Surface Roughness ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Laser Source ◽  
Pulsed Laser Radiation ◽  
Current State ◽  
The Impact

AbstractIt is well known that the surface topography of a part can affect its mechanical performance, which is typical in additive manufacturing. In this context, we report about the surface modification of additive manufactured components made of Titanium 64 (Ti64) and Scalmalloy®, using a pulsed laser, with the aim of reducing their surface roughness. In our experiments, a nanosecond-pulsed infrared laser source with variable pulse durations between 8 and 200 ns was applied. The impact of varying a large number of parameters on the surface quality of the smoothed areas was investigated. The results demonstrated a reduction of surface roughness Sa by more than 80% for Titanium 64 and by 65% for Scalmalloy® samples. This allows to extend the applicability of additive manufactured components beyond the current state of the art and break new ground for the application in various industrial applications such as in aerospace.

Different modulation schemes for direct and external modulators based on various laser sources

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hazem M. El-Hageen ◽  
P.G. Kuppusamy ◽  
Aadel M. Alatwi ◽  
M. Sivaram ◽  
Z. Ahamed Yasar ◽  
...  
Keyword(s):  
Rate Equation ◽  
Simulation Software ◽  
Optical Systems ◽  
Laser Source ◽  
Optical Link ◽  
Input And Output ◽  
Modulation Techniques ◽  
Different Types ◽  
Laser Sources ◽  
Modulation Schemes

AbstractDifferent types of laser source modulation techniques have been used in various applications depending on the objective. As optical systems extract the laws and the best solutions from experiments and simulations, the present study uses simulation software with different modulation types so the output signals can be compared. The modulators used are Mach-Zehnder, which is an external modulator, and electro-absorption modulator and laser rate equation modulator, which are direct modulators. All these types have an optical link multimode (MM) fiber with a photodiode in the receiver end that can be modeled. The input and output signals are analyzed using different types of modulations.

Hologram indexing in LiNbO_3 with a tunable pulsed laser source

1979 ◽  
Vol 18 (15) ◽  
pp. 2555 ◽  
Author(s):  
D. A. Woodbury ◽  
T. A. Rabson ◽  
F. K. Tittel
Keyword(s):  
Pulsed Laser ◽  
Laser Source

scholarly journals Overheating In Silicon During Pulsed-Laser Irradiation?

1985 ◽  
Vol 51 ◽  
Author(s):  
B. C. Larson ◽  
J. Z. Tischler ◽  
D. M. Mills
Keyword(s):  
Laser Irradiation ◽  
Thermal Strain ◽  
Pulsed Laser ◽  
Interface Velocity ◽  
High Energy ◽  
Time Resolved ◽  
Synchrotron Source ◽  
Zero Velocity ◽  
The Difference ◽  
Pulsed Laser Irradiation

ABSTRACTNanosecond resolution time-resolved x-ray diffraction measurements of thermal strain have been used to measure the interface temperatures in silicon during pulsed-laser irradiation. The pulsed-time-structure of the Cornell High Energy Synchrotron Source (CHESS) was used to measure the temperature of the liquid-solid interface of <111> silicon during melting with an interface velocity of 11 m/s, at a time of near zero velocity, and at a regrowth velocity of 6 m/s. The results of these measurements indicate 110 K difference between the temperature of the interface during melting and regrowth, and the measurement at zero velocity shows that most of the difference is associated with undercooling during the regrowth phase.

scholarly journals Time-Resolved Quadrupole Mass Spectrometric Studies on Pulsed Laser Ablation of TiO2

1999 ◽  
Vol 18 (3) ◽  
pp. 99-109 ◽  
Author(s):  
Yongxin Tang ◽  
Zhenhui Han ◽  
Qizong Qin
Keyword(s):  
Laser Ablation ◽  
Continuous Wave ◽  
Center Of Mass ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Ionic Species ◽  
Mass Spectrometric ◽  
Quadrupole Mass ◽  
Time Resolved ◽  
Ambient Oxygen

Pulsed laser ablation of TiO2 at 355 nm and 532 nm has been investigated using an angleand time-resolved quadrupole mass spectrometric technique. The major ablated species include O (m/e = 16), O2 (m/e = 32), Ti (m/e = 48), TiO (m/e = 64) and TiO2 (m/e = 80). The time-of-flight (TOF) spectra of ablated species are measured for the ionic and neutral ablated species, and they can be fitted by a Maxwell – Boltzmann (M – B) distribution with a center-of-mass velocity. The measured angular distributions of the ionic species (O+ and Ti+) and the neutral species (O and Ti) can be fitted with cos⁡nθ and a cos⁡θ + (1−a)cos⁡nθ, respectively. In addition, a continuous wave oxygen molecular beam is introduced into the ablated plume, and the enhancement of the signal intensities of TiO is observed. It implies that the ablated Ti atoms/ions species can react with ambient oxygen molecules in the gas phase. In the meanwhile, the physicochemical mechanism of pulsed laser ablation of TiO2 is discussed.

Early Dynamics of a Laser-induced Underwater Shock Wave

2021 ◽  
Author(s):  
Guihua Lai ◽  
Siyuan Geng ◽  
Hanwen Zheng ◽  
Zhifeng Yao ◽  
Qiang Zhong ◽  
...  
Keyword(s):  
Shock Wave ◽  
Numerical Method ◽  
Cavitation Bubble ◽  
Laser Energy ◽  
Optical Breakdown ◽  
Pulsed Laser ◽  
Underwater Shock Wave ◽  
Time Resolved ◽  
High Attenuation ◽  
Nanosecond Pulsed Laser

Abstract The objective of this paper is to observe and investigate the early evolution of the shock wave, induced by a nanosecond pulsed laser in still water. A numerical method is performed to calculate the propagation of the shock wave within 1µs, after optical breakdown, based on the Gilmore model and the Kirkwood-Bethe hypothesis. The input parameters of the numerical method include the laser pulse duration, the size of the plasma and the maximally extended cavitation bubble, which are measured utilizing a high time-resolved shadowgraph system. The calculation results are verified by shock wave observation experiments at the cavitation bubble expansion stage. The relative errors of the radiuses and the velocity of the shock wave front, reach the maximum value of 45% at 5 ns after breakdown and decrease to less than 20% within 20 ns. The high attenuation characteristics of the shock wave after the optical breakdown, are predicted by the numerical method. The quick time and space evolution of the shock wave are carefully analyzed. The normalized shock wave width is found to be independent of the laser energy and duration, and the energy partitions ratio is around 2.0 using the nanosecond pulsed laser.

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