scholarly journals Frequency-modulated laser beam with highly efficient intensity stabilisation

2005 ◽  
Vol 41 (4) ◽  
pp. 188 ◽  
Author(s):  
F. du Burck ◽  
A. Tabet ◽  
O. Lopez
Keyword(s):  
Laser Beam ◽  
Highly Efficient

Highly efficient terahertz wave filter for high-power laser beam separation

2014 ◽  
Vol 105 (22) ◽  
pp. 221108 ◽  
Author(s):  
Bo Guo ◽  
Jun Tang ◽  
Bin Cai ◽  
YiMing Zhu
Keyword(s):  
Laser Beam ◽  
High Power ◽  
Terahertz Wave ◽  
High Power Laser ◽  
Power Laser ◽  
Highly Efficient ◽  
Wave Filter

scholarly journals Process Window for Highly Efficient Laser-Based Powder Bed Fusion of AlSi10Mg with Reduced Pore Formation

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5255
Author(s):  
Artur Leis ◽  
Rudolf Weber ◽  
Thomas Graf
Keyword(s):  
Laser Beam ◽  
Process Efficiency ◽  
Process Window ◽  
Deep Penetration ◽  
Optimum Process ◽  
Beam Diameter ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Highly Efficient ◽  
Low Porosity

The process window for highly efficient laser-based powder bed fusion (LPBF), ensuring the production of parts with low porosity, was determined by analyzing cross-sections of samples that were generated with laser powers varying between 10.8 W and 1754 W, laser beam diameters varying between 35 μm and 200 μm, and velocities of the moving laser beam ranging between 0.7 m/s and 1.3 m/s. With these parameters, the process alters between different modes that are referred to as simple heating, heat conduction melting (HCM), key-bowl melting (KBM), and deep-penetration melting (DPM). It was found that the optimum process window for a highly efficient LPBF process, generating AlSi10Mg parts with low porosity, is determined by the ratio PL/db of the incident laser power PL and the beam diameter db of the beam on the surface of the bead, and ranges between PL/db = 2000 W/mm and PL/db = 5200 W/mm, showing process efficiencies of about 7–8%. This optimum process window is centered around the range PL/db = 3000–3500 W/mm, in which the process is characterized by KBM, which is an intermediate process mode between HCM and DPM. Processes with PL/db < 2000 W/mm partially failed, and lead to balling and a lack of fusion, whereas processes with PL/db > 5200 W/mm showed a process efficiency below 5% and pore ratios exceeding 10%.

Highly Efficient, Phase-Matched High-Harmonic Generation by a Self-Guided Laser Beam

1999 ◽  
Vol 82 (7) ◽  
pp. 1422-1425 ◽  
Author(s):  
Yusuke Tamaki ◽  
Jiro Itatani ◽  
Yutaka Nagata ◽  
Minoru Obara ◽  
Katsumi Midorikawa
Keyword(s):  
Laser Beam ◽  
Harmonic Generation ◽  
High Harmonic ◽  
High Harmonic Generation ◽  
Highly Efficient

Two-photon excitation microscopy in cellular biophysics

1995 ◽  
Vol 53 ◽  
pp. 62-63
Author(s):  
David W. Piston ◽  
Brian D. Bennett ◽  
Robert G. Summers
Keyword(s):  
Confocal Microscopy ◽  
Laser Beam ◽  
Duty Cycle ◽  
Excited Electronic State ◽  
Input Power ◽  
Two Photon ◽  
Simultaneous Absorption ◽  
Photon Excitation ◽  
Very High ◽  
Two Photon Excitation

Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10-5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.

The atomic-force microscope and its future in biology

1993 ◽  
Vol 51 ◽  
pp. 704-705
Author(s):  
Jean-Paul Revel
Keyword(s):  
Silicon Nitride ◽  
Laser Beam ◽  
Atomic Force Microscope ◽  
Scanning Tunneling Microscope ◽  
Point Of View ◽  
Scanning Tunneling ◽  
Close Relative ◽  
Tunneling Microscope ◽  
Atomic Force ◽  
Sharp Point

The last few years have been marked by a series of remarkable developments in microscopy. Perhaps the most amazing of these is the growth of microscopies which use devices where the place of the lens has been taken by probes, which record information about the sample and display it in a spatial from the point of view of the context. From the point of view of the biologist one of the most promising of these microscopies without lenses is the scanned force microscope, aka atomic force microscope.This instrument was invented by Binnig, Quate and Gerber and is a close relative of the scanning tunneling microscope. Today's AFMs consist of a cantilever which bears a sharp point at its end. Often this is a silicon nitride pyramid, but there are many variations, the object of which is to make the tip sharper. A laser beam is directed at the back of the cantilever and is reflected into a split, or quadrant photodiode.

Highly efficient and selective photocatalytic CO2 to CO conversion in aqueous solution

2020 ◽  
Vol 56 (27) ◽  
pp. 3851-3854 ◽  
Author(s):  
Xiaomin Chai ◽  
Hai-Hua Huang ◽  
Huiping Liu ◽  
Zhuofeng Ke ◽  
Wen-Wen Yong ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Photocatalytic Performance ◽  
Aqueous Media ◽  
Highly Efficient ◽  
Co Conversion

A Co-based complex displayed the highest photocatalytic performance for CO2 to CO conversion in aqueous media.

Tuning the pore structures and photocatalytic properties of a 2D covalent organic framework with multi-branched photoactive moieties

Nanoscale ◽  
2020 ◽  
Vol 12 (30) ◽  
pp. 16136-16142
Author(s):  
Xuan Wang ◽  
Ming-Jie Dong ◽  
Chuan-De Wu
Keyword(s):  
Photocatalytic Properties ◽  
Effective Strategy ◽  
Covalent Organic Framework ◽  
Highly Efficient ◽  
Pore Structures ◽  
Local Connection ◽  
Organic Framework

An effective strategy to incorporate accessible metalloporphyrin photoactive sites into 2D COFs by establishing a 3D local connection for highly efficient photocatalysis was developed.

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