Measurement of the Laser Exposure Levels for Burn Threshold in Biological Tissue

1984 ◽  
Vol 106 (3) ◽  
pp. 283-284 ◽  
Author(s):  
G. Laufer ◽  
H. Z. Joachims ◽  
I. Eliachar ◽  
D. Mordechovitz
Keyword(s):  
Theoretical Model ◽  
Soft Tissue ◽  
Energy Density ◽  
Biological Tissue ◽  
Pain Threshold ◽  
Laser Energy ◽  
Laser Energy Density ◽  
Laser Exposure ◽  
Safety Standards ◽  
Exposure Levels

Experiments for the evaluation of the laser energy density required to induce burn threshold in biological tissue are presented. The results are compared with a theoretical model. The values obtained for soft tissue are higher than the pain threshold and the safety standards for the maximum permissible exposure. This is due to the different nature of injury associated with the surgical process.

Selective ablation of biological tissue and single cells on a glass substrate by controlling the laser energy density of nanosecond 193 nm laser radiation

2019 ◽  
Vol 34 (10) ◽  
pp. 1957-1964 ◽  
Author(s):  
Thibaut Van Acker ◽  
Stijn J. M. Van Malderen ◽  
Legna Colina-Vegas ◽  
Ranjith K. Ramachandran ◽  
Frank Vanhaecke
Keyword(s):  
Laser Radiation ◽  
Energy Density ◽  
Biological Tissue ◽  
Glass Substrate ◽  
Biological Material ◽  
Laser Energy ◽  
Single Cells ◽  
Laser Energy Density ◽  
Selective Ablation ◽  
193 Nm

This work demonstrates the ability of nanosecond 193 nm laser radiation to selectively ablate biological material on a glass substrate.

Fundamentals of radiation heat transfer in AlSi10Mg powder bed during selective laser melting

2019 ◽  
Vol 25 (9) ◽  
pp. 1506-1515 ◽  
Author(s):  
Pei Wei ◽  
Zhengying Wei ◽  
Zhne Chen ◽  
Jun Du ◽  
Yuyang He ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Density ◽  
Negative Impact ◽  
Laser Energy ◽  
Melting Process ◽  
Laser Energy Density ◽  
Granular System ◽  
Laser Melting ◽  
Content Type ◽  
Powder Bed

Purpose This paper aims to study numerically the influence of the applied laser energy density and the porosity of the powder bed on the thermal behavior of the melt and the resultant instability of the liquid track. Design/methodology/approach A three-dimensional model was proposed to predict local powder melting process. The model accounts for heat transfer, melting, solidification and evaporation in granular system at particle scale. The proposed model has been proved to be a good approach for the simulation of the laser melting process. Findings The results shows that the applied laser energy density has a significantly influence on the shape of the molten pool and the local thermal properties. The relative low or high input laser energy density has the main negative impact on the stability of the scan track. Decreasing the porosity of the powder bed lowers the heat dissipation in the downward direction, resulting in a shallower melt pool, whereas pushing results in improvement in liquid track quality. Originality/value The randomly packed powder bed is calculated using discrete element method. The powder particle information including particle size distribution and packing density is taken into account in placement of individual particles. The effect of volumetric shrinkage and evaporation is considered in numerical model.

Effects of laser energy density on in situ formation of nano-graphite

2019 ◽  
Vol 48 (5) ◽  
pp. 506004
Author(s):  
刘孝谦 Liu Xiaoqian ◽  
骆 芳 Luo Fang ◽  
杜琳琳 Du Linlin ◽  
陆潇晓 Lu Xiaoxiao
Keyword(s):  
Energy Density ◽  
Laser Energy ◽  
Laser Energy Density ◽  
In Situ Formation

Considerations for Large Area Fabrication of Integrated a-Si and Poly-Si TFTs

1994 ◽  
Vol 336 ◽  
Author(s):  
P. Mei ◽  
G. B. Anderson ◽  
J. B. Boyce ◽  
D. K. Fork ◽  
M. Hack ◽  
...  
Keyword(s):  
Grain Size ◽  
Energy Density ◽  
Laser Energy ◽  
Gate Insulator ◽  
Laser Energy Density ◽  
Laser Crystallization ◽  
Large Area ◽  
Low Leakage ◽  
Threshold Voltages ◽  
Excellent Method

ABSTRACTThe combination of a-Si low leakage pixel TFTs with poly-Si TFTs in peripheral circuits provides an excellent method for reducing the number of external connections to large-area imaging arrays and displays. To integrate the fabrication of the peripheral poly-Si TFTs with the a-Si pixel TFTs, we have developed a three-step laser process which enables selective crystallization of PECVD a-Si:H. X-ray diffraction and transmission electron microscopy show that the polycrystalline grains formed with this three-step process are similar to those crystallized by a conventional one step laser crystallization of unhydrogenated amorphous silicon. The grain size increases with increasing laser energy density up to a peak value of a few Microns. The grain size decreases with further increases in laser energy density. The transistor field effect mobility is correlated with the grain size, increasing gradually with laser energy density until reaching its maximum value. Thereafter, the transistors suffer from leakage through the gate insulators. A dual dielectric gate insulator has been developed for these bottom-gate thin film transistors to provide the correct threshold voltages for both a-Si and poly-Si TFTs.

The effect of laser energy density and target-substrate distance on the quality of YBa2Cu3O7-xthin films

1994 ◽  
Vol 7 (6) ◽  
pp. 435-437 ◽  
Author(s):  
S F Xu ◽  
Y J Tian ◽  
H S Lu ◽  
D F Cui ◽  
Z H Chen ◽  
...  
Keyword(s):  
Energy Density ◽  
Laser Energy ◽  
Laser Energy Density ◽  
Substrate Distance
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