scholarly journals Integrating sphere photodetector for measurement of continuous-wave and peak laser power

1976 ◽  
Author(s):  
L.D. Wonnell
Keyword(s):  
Laser Power ◽  
Continuous Wave ◽  
Integrating Sphere ◽  
Peak Laser Power

scholarly journals Synchronized Optical and Acoustic Droplet Vaporization for Effective Sonoporation

Pharmaceutics ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 279 ◽  
Author(s):  
Wei-Wen Liu ◽  
Sy-Han Huang ◽  
Pai-Chi Li
Keyword(s):  
Laser Power ◽  
Continuous Wave ◽  
Synergistic Effects ◽  
Tumor Therapy ◽  
Average Power ◽  
Acoustic Droplet Vaporization ◽  
Droplet Vaporization ◽  
Inertial Cavitation ◽  
Cw Laser ◽  
Ultrasound Pulse

Inertial cavitation-based sonoporation has been utilized to enhance treatment delivery efficacy. In our previous study, we demonstrated that tumor therapeutic efficacy can be enhanced through vaporization-assisted sonoporation with gold nanodroplets (AuNDs). Specifically, the AuNDs were vaporized both acoustically (i.e., acoustic droplet vaporization, ADV) and optically (i.e., optical droplet vaporization, ODV). A continuous wave (CW) laser was used for ODV in combination with an ultrasound pulse for ADV. Although effective for vaporization, the use of a CW laser is not energy efficient and may create unwanted heating and concomitant tissue damage. In this study, we propose the use of a pulsed wave (PW) laser to replace the CW laser. In addition, the PW laser was applied at the rarefaction phase of the ultrasound pulse so that the synergistic effects of ADV and ODV can be expected. Therefore, a significantly lower laser average power can be expected to achieve the vaporization threshold. Compared to the CW laser power at 2 W/cm2 from the previous approach, the PW laser power was reduced to only 0.2404 W/cm2. Furthermore, we also demonstrate in vitro that the sonoporation rate was increased when the PW laser was applied at the rarefaction phase. Specifically, the vaporization signal, the inertial cavitation signal, and the sonoporation rate all displayed a 1-µs period, which corresponded to the period of the 1-MHz acoustic wave used for ADV, as a function of the relative laser delay. The increased sonoporation rate indicates that this technique has the potential to enhance sonoporation-directed drug delivery and tumor therapy with a lower laser power while keeping the cell death rate at the minimum. Photoacoustic imaging can also be performed at the same time since a PW laser is used for the ODV.

Laser Sintering of Aerosol Jet Printed Interconnects on Flexible Substrate

2019 ◽  
Vol 2019 (1) ◽  
pp. 000404-000408 ◽  
Author(s):  
Mohammed Alhendi ◽  
Ludovico Cestarollo ◽  
Gurvinder S. Khinda ◽  
Darshana L. Weerawarne ◽  
Mark D. Poliks
Keyword(s):  
Laser Power ◽  
Continuous Wave ◽  
Flexible Substrate ◽  
Statistical Design ◽  
Laser Sintering ◽  
Continuous Wave Laser ◽  
Convection Oven ◽  
Wave Laser ◽  
Nanoparticle Ink ◽  
Full Factorial

Abstract Laser sintering of interconnects printed on flexible substrate with silver nanoparticle ink is studied as an alternative to convection oven sintering. Interconnects of 80 μm and 250 μm line width are printed using an aerosol jet printer and sintered using an 830 nm continuous wave laser. A conductivity that is 4.5× higher than that of an oven sintered interconnect is achieved at optimal laser power and sintering speed set using a full factorial statistical design.

Force Modeling in Laser-Assisted Microgrooving Including the Effect of Machine Deflection

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
Ramesh Singh ◽  
Shreyes N. Melkote
Keyword(s):  
Flow Stress ◽  
Cutting Force ◽  
Cutting Forces ◽  
Laser Power ◽  
Continuous Wave ◽  
Dimensional Accuracy ◽  
Thermal Softening ◽  
Depth Of Cut ◽  
Force Model ◽  
Cutting Force Model

Laser assisted mechanical micromachining is a process that utilizes highly localized thermal softening of the material by continuous wave laser irradiation applied simultaneously and directly in front of a miniature cutting tool in order to produce micron scale three-dimensional features in difficult-to-machine materials. The hybrid process is characterized by lower cutting forces and deflections, fewer tool failures, and potentially higher material removal rates. The desktop-sized machine used to implement this process has a finite stiffness and deflects under the influence of the cutting forces. The deflections can be of the same order of magnitude as the depth of cut in some cases, thereby having a negative effect on the dimensional accuracy of the micromachined feature. As a result, selection of the laser and cutting parameters that yield the desired reduction in cutting forces and deflection, and consequently an improvement in dimensional accuracy, requires a reliable cutting force model. This paper describes a cutting force model for the laser-assisted microgrooving process. The model accounts for the effect of elastic deflection of the machine X-Y stages on the forces and accuracy of the micromachined feature. The model combines an existing slip-line field based force model with a finite element based thermal model of laser heating and a constitutive material flow stress model to account for thermal softening. Experiments are carried out on H-13 steel (42 HRC (hardness measured on the Rockwell ‘C’ scale)) to validate the force model. The effects of process parameters, such as laser power and cutting speed, on the forces are also analyzed. The model captures the effect of thermal softening and indicates a 66% reduction in the shear flow stress at 35 W laser power. The cutting force and depth of cut prediction errors are less than 20% and 10%, respectively, for most of the cases examined.

Continuous wave-CO2 laser power control process applied to welding

2001 ◽  
Vol 215 (3) ◽  
pp. 395-402
Author(s):  
P Deprez ◽  
P Vantomme ◽  
J F Coutouly ◽  
A Deffontaine ◽  
J F Ramiere
Keyword(s):  
Power Control ◽  
Co2 Laser ◽  
Laser Power ◽  
Continuous Wave ◽  
Control Process

Effects of peak laser power on laser micro sintering of nickel powder by pulsed Nd:YAG laser

2014 ◽  
Vol 20 (4) ◽  
pp. 328-335 ◽  
Author(s):  
Linda Ke ◽  
Haihong Zhu ◽  
Jie Yin ◽  
Xinbing Wang
Keyword(s):  
Nd:Yag Laser ◽  
Laser Power ◽  
Peak Power ◽  
Nickel Powder ◽  
Pulsed Laser ◽  
Laser Sintering ◽  
High Peak Power ◽  
Content Type ◽  
Power Intensity ◽  
Peak Laser Power

Purpose – The purpose of this paper is to report the influence of the peak laser power on laser micro sintering 4-μm nickel powder using Q-switched 1064-nm Nd:YAG laser. Design/methodology/approach – Experimental study has been performed. Nickel powder with grain size of 4 μm has been utilized. A Q-switching duration of 20-25 μs and rate of 20-40 kHz have been used. Findings – The peak power intensity is so high that the metal particles and molten pool are blown away, leading to laser micro sintering not being successfully proceeded. The scanning line obtained by continuous-wave (CW) laser looks like a rod owing to balling effect. Using a suitable peak power intensity, a good-shaped sintering line can be obtained because the plasma can protect the molten metal from oxidation, and improve the wettability of the system. In addition, the plasma flattening effect may also contribute to the form of the good-shaped sintering line in pulsed laser sintering regime. Originality/value – The role of plasma induced by pulsed laser with high peak power intensity has been found during pulsed laser sintering under an ambient environment.

scholarly journals Power controllable gain switched fiber laser at ~ 3 μm and ~ 2.1 μm

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yiwen Shi ◽  
Jianfeng Li ◽  
Chendong Lai ◽  
Hanlin Peng ◽  
Chen Zhu ◽  
...  
Keyword(s):  
Pump Power ◽  
Low Power ◽  
Fiber Laser ◽  
Output Power ◽  
Laser Power ◽  
Continuous Wave ◽  
Pulsed Laser ◽  
Maximum Output ◽  
Pump Source

AbstractBased on a hybrid pumping method consisting of a 1150 nm continuous-wave pump source and a 1950 nm pulsed pump source, we demonstrate a power controllable gain-switched fiber laser in dual wavebands at ~ 3 μm and ~ 2.1 μm. Different pumping schemes for pumping a Ho3+-doped ZBLAN fiber are studied. Using only the 1950 nm pulsed pump source, ~ 2.1 μm gain-switched pulses with single and double pulses are obtained separately at different pump powers. This phenomenon indicates that the 1950 nm pulsed pump source acts as a modulator to trigger different states of the ~ 2.1 μm pulses. Moreover, by fixing the 1150 nm pump power at 3.259 W and adjusting the 1950 nm pump power, the output power of the ~ 2.1 μm gain-switched pulsed laser is flexibly controlled while the ~ 3 μm laser power is almost unchanged, inducing the maximum output powers of 167.96 mW and 260.27 mW at 2910.16 nm and 2061.65 nm, respectively. These results suggest that the comparatively low power of the ~ 2.1 μm gain-switched pulsed laser in dual-waveband laser can be efficiently overcome by reasonably controlling the 1950 nm pump power.

Investigation of Image Characteristics of Plume and Spatters during High-Power Disk Laser Welding

2013 ◽  
Vol 709 ◽  
pp. 301-304 ◽  
Author(s):  
Gui Qian Liu ◽  
Xiang Dong Gao
Keyword(s):  
Laser Welding ◽  
High Power ◽  
Laser Power ◽  
High Speed ◽  
Continuous Wave ◽  
Welding Process ◽  
Metal Vapor ◽  
High Speed Photography ◽  
Monitoring And Control ◽  
Disk Laser

During high-power laser welding process, the workpiece produces metal vapor because of the laser irradiation. The characteristics of metal vapor are related to the quality and stability of welding and the utilization of the laser power. An approach of analyzing the characteristics of metal vapor was researched during high-power disk laser bead-on-plate welding of Type 304 austenitic stainless steel plates at a continuous wave laser power of 10 kW. A high-speed photography was used to capture metal vapor dynamic images. Metal vapor area, beam path, swing angle are calculated by image processing, which is the foundation for monitoring and control of welding quality in real time.

Absorptivity of SiF4 at 1027 cm−1 for High Continuous-Wave Laser Power

1996 ◽  
Vol 50 (3) ◽  
pp. 420-422 ◽  
Author(s):  
Aaron Sandoski ◽  
Joseph J. BeIBruno
Keyword(s):  
Laser Power ◽  
Continuous Wave ◽  
Continuous Wave Laser ◽  
Wave Laser
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