High sensitivity in-plane strain measurement using a laser scanning technique

2014 ◽  
Author(s):  
Hanshuang Liang ◽  
Teng Ma ◽  
Cheng Lv ◽  
Hoa Nguyen ◽  
George Chen ◽  
...  
Keyword(s):  
Plane Strain ◽  
Strain Measurement ◽  
Laser Scanning ◽  
High Sensitivity ◽  
Scanning Technique

Laser Scanning Technique for the Investigation of Power Devices

2009 ◽  
pp. 239-239-12 ◽  
Author(s):  
O Engström ◽  
B Drugge ◽  
PA Tove
Keyword(s):  
Laser Scanning ◽  
Power Devices ◽  
Scanning Technique

scholarly journals Laser-metal interaction dynamics during additive manufacturing resolved by detection of thermally-induced electron emission

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Philip J. DePond ◽  
John C. Fuller ◽  
Saad A. Khairallah ◽  
Justin R. Angus ◽  
Gabe Guss ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Laser Scanning ◽  
Surface Defects ◽  
Thermal Emission ◽  
Thermionic Emission ◽  
High Sensitivity ◽  
Precise Determination ◽  
Diagnostic Methods ◽  
In Situ Monitoring ◽  
Interaction Dynamics

AbstractIn situ monitoring is required to improve the understanding and increase the reliability of additive manufacturing methods such as laser powder bed fusion (LPBF). Current diagnostic methods for LPBF capture optical images, X-ray radiographs, or measure the emission of thermal or acoustic signals from the component. Herein, a methodology based on the thermal emission of electrons - thermionic emission - from the metal surface during LPBF is proposed which can resolve laser-material interaction dynamics. The high sensitivity of thermionic emission to surface temperature and surface morphology is revealed to enable precise determination of the transition between conduction and keyhole mode melting regimes. Increases in thermionic emission are correlated to laser scanning conditions that give rise to pore formation and regions where surface defects are pronounced. The information presented here is a critical step in furthering our understanding and validation of laser-based metal additive manufacturing.

scholarly journals Photophysical and photochemical properties of electronically excited fluorescent dyes: a new type of time-resolved laser-scanning spectroscopy

1999 ◽  
Vol 1 (3) ◽  
pp. 165-172 ◽  
Author(s):  
Ma. Heupel ◽  
I. Gregor ◽  
St. Becker ◽  
E. Thiel
Keyword(s):  
Molecular Oxygen ◽  
Laser Scanning ◽  
Fluorescent Dyes ◽  
High Sensitivity ◽  
Ambient Conditions ◽  
Time Resolved ◽  
Electronically Excited ◽  
New Type ◽  
Photochemical Properties ◽  
Scanning Spectroscopy

The capacity of a new type of time-resolved laser-scanning spectroscopy is discussed. Due to the developed modulation technique we obtain a high sensitivity in the absorption measurement as well as a very efficient suppression of the background absorption. The new technique has been used to investigate photophysical and photochemical properties of fluorescent dyes. All presented results are discussed in view of potential applications like dye laser and fluorescence labelling.The possibility of intermolecular triplet state quenching by molecular oxygen and further agents is considered in detail. The quenching process is described in terms of diffusion controlled interaction. It is shown that under ambient conditions quenching agents can inhibit the quenching by molecular oxygen and therefore the generation of the chemically highly reactive singlet molecular oxygen. It can be expected that the obtained information can be used in order to increase the photostability not only of rhodamine dyes.

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