scholarly journals Room temperature laser power standard using a microfabricated, electrical substitution bolometer

2021 ◽  
Vol 92 (2) ◽  
pp. 025107
Author(s):  
M. Stephens ◽  
C. S. Yung ◽  
N. A. Tomlin ◽  
A. Vaskuri ◽  
I. Ryger ◽  
...  
Keyword(s):  
Laser Power ◽  
Room Temperature ◽  
Power Standard

scholarly journals Temperature Calibration Measurements based on Laser-Induced Phosphorescence Technique for Combustion Applications

2015 ◽  
Vol 10 (1) ◽  
Keyword(s):  
Laser Radiation ◽  
Laser Beam ◽  
Intensity Ratio ◽  
Laser Power ◽  
Room Temperature ◽  
Pulsed Laser ◽  
Temperature Calibration ◽  
Phosphor Powder ◽  
Calibration Methods

Phosphor powder and phosphor-binder mixtures are successfully employed for temperature calibration measurements by using laser-induced phosphorescence (LIP) technique with an emphasis on higher precisions and accuracies than other non-intrusive methods. The phosphorescence intensities are used to perform these calibrations in three different strategies. The influence of laser power regular changes on particles heating and the calibration analyses is also carried out. A pulsed laser at 355 nm was used for exciting specimens of the phosphor powder as well as the phosphor-binder mixtures. The laser beam was directed onto the specimens and varied in three laser power levels (LPLs). The samples were kept in an oven with temperatures ranging from room temperature up to 1800 °C. The three strategies which are expressed in terms of non-dimensional intensity versus wavelength (NDI-W), normalised intensity (NI) and intensity ratio (IR) were used for the calibration assessments. A modified IR was compared with two different IRs. A precision of around ± (0.50-1.41)% was attained for different calibration methods. This research confirmed that these calibrations are possible using three different strategies, given high precisions and accuracies. The laser power alternations influenced the NI and do affect neither the NDI-W nor the IR curves. The laser radiation does not play any role for heating the particles of the studied powder.

Determination of x-ray free electron laser power using a room-temperature calorimeter

Metrologia ◽  
2016 ◽  
Vol 53 (1) ◽  
pp. 98-102 ◽  
Author(s):  
T Tanaka ◽  
M Kato ◽  
N Saito ◽  
K Tono ◽  
M Yabashi ◽  
...  
Keyword(s):  
Free Electron ◽  
Free Electron Laser ◽  
Laser Power ◽  
Room Temperature ◽  
X Ray

Copper Laser Induced Chemical Vapor Deposition of al Films

1990 ◽  
Vol 201 ◽  
Author(s):  
M. I. Yankova ◽  
W. Shanov ◽  
B. Ivanov
Keyword(s):  
Laser Power ◽  
Room Temperature ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Single Step ◽  
Laser Power Density ◽  
Chemical Compositions ◽  
Silicon Substrates ◽  
Direct Writing ◽  
Scanning Velocity

AbstractThe focused output from a copper laser (λ = 510nm) has been used for direct writing of Al on silicon substrates by pyrolitical decomposition of trimethilaluminum (TMA). These results demonstrate that direct writing can be accomplished at room temperature by a single-step deposition process induced by a single light source. For a laser power density between 5 and 50 kW cm−2, the widths of the stripes varied between 60 and 200 μm with corresponding thickness between 0.5 and 0.8 μm. The width of the stripes proved to be independent of the scanning velocity, Vs, within the range 50 μm s−1 < Vs < 300 μm s−1. The analysis included scanning electron microscopy (SEM) to study the film morphology, a step profiler to evaluate the thicknesses and the profiles of the stripes, and energy dispersive spectroscopy (EDS) to provide their chemical compositions.

Quenched-In Defects in CW Laser-Annealed Si

1981 ◽  
Vol 4 ◽  
Author(s):  
N.H. Sheng ◽  
J.L. Merz
Keyword(s):  
Laser Power ◽  
Room Temperature ◽  
Laser Annealing ◽  
Minority Carrier ◽  
Deep Hole ◽  
Carrier Injection ◽  
Furnace Annealing ◽  
Shallow Level ◽  
Cw Laser ◽  
Induced Defects

ABSTRACTDLTS has been used to investigate the nature of CW laser-induced defects in ion-implanted Si. A dominant hole trap (∼Ev + 0.45 eV), whose concentration depends on laser power, was observed immediately after sample preparation. This defect is not stable at room temperature; instead, it decays as a function of time, transmuting to a shallow level at Ev + 0.10 eV. The recovery of the Ev + 0.45 eV level can be stimulated by low temperature thermal annealing or by minority carrier injection. By comparing these defects in laser-annealed samples with defects produced by furnace annealing followed by rapid cooling, and with other published results, the laser-induced defects have beenidentified as interstitial Fe and Fe-B pairs. Experiments suggest that elevated substrate temperature during laser annealing may inhibit the formation of these deep hole traps.

Laser Induced Phase Transformations in Thin Insb Films

1993 ◽  
Vol 311 ◽  
Author(s):  
L.L. Chou ◽  
M.M. Kuo
Keyword(s):  
Phase Transformations ◽  
Laser Power ◽  
Room Temperature ◽  
Flash Evaporation ◽  
Glass Substrates ◽  
Grain Sizes ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Migration Mechanism ◽  
20 Nm

ABSTRACTThin In46Sb54 films have been prepared on glass substrates by flash evaporation. Films of 1000 Å were deposited at room temperature. After 7 mins' thermal annealing at 450ºC, an average grain size increased from 20 nm to 200 nm. Under exposure to a Fraunhofer diffracted pulsed Nd-YAG laser beam, the films showed different microstructures for different applied laser power. In general, five regions are identified: ablation region, regions with grain sizes less than 20 nm, grain sizes ranging from 400 to 1000 nm, grain sizes ranging from 200 to 400 nm and unchanged region. The previous five regions are counted from the center of the exposed area outward. The pulse duration is 16 ns. In this paper, an atomic migration mechanism is proposed to explain the power dependent microstructures changes. Transmission electron microscopy was mainly used to characterize the films. The application of this type of phase transformations in the phase change optical storage is also discussed.

A Study of Fiber Laser Micro-Grooving of 316L Stainless Steel at Different Temperatures

2021 ◽  
pp. 251659842098436
Author(s):  
A. Sen ◽  
B. Doloi ◽  
B. Bhattacharyya
Keyword(s):  
Stainless Steel ◽  
Fiber Laser ◽  
Process Parameters ◽  
Laser Power ◽  
Room Temperature ◽  
316L Stainless Steel ◽  
Cutting Speed ◽  
Pulse Frequency ◽  
Different Temperatures ◽  
Haz Width

The present article deals with the generation of micro-grooves on 316L stainless steel (SS) by a nanosecond pulsed fiber laser system. Fabrication of micro-grooves on 316L SS has immensely contributed to the biomedical and automotive industries through improving the mechanical, lubrication, and corrosion resistance properties. In the present work, the considered process parameters are the preheating temperature (100°C and 200°C), along with the room temperature (24°C), cutting speed, sawing angle, pulse frequency, and laser power. The ranges of cutting speed and sawing angle are 0.1–1.1 mm s−1 and 0.1°–1°, respectively. Besides, pulse frequency and laser power vary from 55 kHz to 85 kHz and from 15 W to 45 W, respectively. The constant parameters are the pulse width of 99% and assist air pressure of 6 kgf cm−2. The variable parameters for the analysis are cut width and heat-affected zone (HAZ) width. The article aims to showcase a comprehensive study of fiber laser process parameters at different temperatures (preheated condition and room temperature) with variable sawing angles to produce better process control and bring about each considered process parameter’s critical value. The experimental results show that higher dimensions of cut width and HAZ width are observed at 200°C with the increment of sawing angle and laser power, compared to other temperatures. With the increment of cutting speed and laser power, the HAZ width tends to rise sharply. A significant drop in cut width and HAZ width dimensions is observed with the increment in pulse frequency for any temperature.

Studies on Dissimilar Welding of AA5083 and AA6061 Alloys by Laser Beam Welding

2012 ◽  
Vol 626 ◽  
pp. 701-705
Author(s):  
B. Srinivas ◽  
K. Sivaprasad ◽  
N. Kishore Babu ◽  
V. Muthupandi ◽  
P. Susila
Keyword(s):  
Temperature Gradient ◽  
Laser Power ◽  
Room Temperature ◽  
Laser Beam Welding ◽  
Spot Size ◽  
Dissimilar Welding ◽  
Beam Spot ◽  
Beam Spot Size ◽  
Dissimilar Welds ◽  
Hardness Values

Dissimilar welds were prepared between 4 mm thick AA5083 and AA6061 sheets using Nd-YAG laser welding with different laser power, beam spot sizes and welding speeds. The results show that the temperature gradient and cooling rates play a major role in resultant microstructures of the weldments. Room temperature hardness and tensile properties of the weldments in the as-welded condition were studied and correlated with the microstructure. The microhardness examination showed that there was significant variation in hardness values at AA6061 side when compared with AA5083 side due to steeper temperature gradient. It has been observed that welds prepared with 3.5kW laser power, 3.5 m/min welding speed and 180 µm beam spot size exhibited highest tensile strength of 241 MPa.

E-BEAM PUMPED VCSEL ON MOVPE-GROWN HEXAGONAL CdSSe/CdS MQW STRUCTURE

2004 ◽  
Vol 03 (01n02) ◽  
pp. 213-221
Author(s):  
V. I. KOZLOVSKY ◽  
V. Yu. BONDAREV ◽  
D. A. SANNIKOV ◽  
P. I. KUZNETSOV ◽  
G. G. YAKUSHCHEVA ◽  
...  
Keyword(s):  
Electron Beam ◽  
Surface Morphology ◽  
Electron Energy ◽  
Vapor Phase ◽  
Spectral Range ◽  
Laser Power ◽  
Room Temperature ◽  
Threshold Current ◽  
Band Alignment ◽  
Type Ii

The first electron-beam pumped VCSEL was fabricated on CdSSe / CdS MQW structure grown by metalorganic vapor phase epitaxy on CdS substrate misoriented by 12–16° from (0001) towards (1010). Substrate misorientation results in more perfect surface morphology and intense cathodoluminesence. Lasing in the 535–590 nm spectral range was achieved at room temperature with different VCSELs. The laser power maximum of one VCSEL was as high as 2 W at RT, with electron energy 50 keV and current 1.7 mA. The threshold current was lower than that for the bulk CdSSe laser although the heterostructure used in the VCSEL has the type-II band alignment.

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