Estimation of side-hole location using circular wavefront of scattering waves visualized by pulsed laser scanning

2012 ◽  
Author(s):  
Tetsuya Yamamoto ◽  
Hiroshi Tsuda ◽  
Junji Takatsubo
Keyword(s):  
Laser Scanning ◽  
Pulsed Laser ◽  
Side Hole ◽  
Circular Wavefront

scholarly journals Heat impact during laser ablation extraction of mineralised tissue micropillars

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Samuel McPhee ◽  
Alexander Groetsch ◽  
Jonathan D. Shephard ◽  
Uwe Wolfram
Keyword(s):  
Laser Ablation ◽  
Mechanical Testing ◽  
Laser Scanning ◽  
Pulsed Laser ◽  
Temperature Response ◽  
Collagen Fibre ◽  
Pulsed Laser Ablation ◽  
Collagen Molecules ◽  
Ultrashort Pulsed Laser ◽  
The Impact

AbstractThe underlying constraint of ultrashort pulsed laser ablation in both the clinical and micromachining setting is the uncertainty regarding the impact on the composition of material surrounding the ablated region. A heat model representing the laser-tissue interaction was implemented into a finite element suite to assess the cumulative temperature response of bone during ultrashort pulsed laser ablation. As an example, we focus on the extraction of mineralised collagen fibre micropillars. Laser induced heating can cause denaturation of the collagen, resulting in ultrastructural loss which could affect mechanical testing results. Laser parameters were taken from a used micropillar extraction protocol. The laser scanning pattern consisted of 4085 pulses, with a final radial pass being 22 $$\upmu {\text {m}}$$ μ m away from the micropillar. The micropillar temperature was elevated to 70.58 $$^{\circ }{\text {C}}$$ ∘ C , remaining 79.42 $$^{\circ }{\text {C}}$$ ∘ C lower than that of which we interpret as an onset for denaturation. We verified the results by means of Raman microscopy and Energy Dispersive X-ray Microanalysis and found the laser-material interaction had no effect on the collagen molecules or mineral nanocrystals that constitute the micropillars. We, thus, show that ultrashort pulsed laser ablation is a safe and viable tool to fabricate bone specimens for mechanical testing at the micro- and nanoscale and we provide a computational model to efficiently assess this.

Fabrication of large area superconducting thin film by pulsed laser scanning

1999 ◽  
Vol 9 (2) ◽  
pp. 2355-2358
Author(s):  
Q.L. Wang ◽  
C.W. An ◽  
W.D. Song ◽  
S.S. Oh ◽  
K.S. Ryu ◽  
...  
Keyword(s):  
Thin Film ◽  
Laser Scanning ◽  
Pulsed Laser ◽  
Large Area ◽  
Superconducting Thin Film

Machining and Characterization of Deep Micro Holes on Super Alloy Processed by Millisecond Pulsed Laser

2016 ◽  
Vol 703 ◽  
pp. 34-38 ◽  
Author(s):  
Yun Long Wang ◽  
Lin Zhong Zhu ◽  
Cai Yan Chen ◽  
Zhi Chen Liu ◽  
Wei Xin Ren ◽  
...  
Keyword(s):  
Laser Power ◽  
Laser Scanning ◽  
Pulsed Laser ◽  
Processing System ◽  
Longitudinal Section ◽  
Recast Layer ◽  
Numerical Control ◽  
Micro Cracks ◽  
Micro Holes ◽  
Super Alloy

In this study, a series of deep micro holes were machined on thick GH4169 super alloy by the trepan drilling, using a millisecond pulsed laser which equipped to the numerical control processing system. The microstructure of the holes including surface and longitudinal morphologies, diameter, taper, circularity, micro cracks and recast layer were systematically characterized. The surface morphology and the longitudinal section of the drilled holes were observed by Scanning Electron Microscope and 3D Laser Scanning Confocal Microscope. The method of Minimum circumcircle method was employed to evaluate the entrance and exit end circularity. The results showed that the melt and spattering accumulating around the holes decreased with the augment of laser power. The diameter of the entrance showed an increasing tendency with the growing of laser power, but the exit end was not seriously affected by the power. The micro cracks and recast layer could be found obviously, the micro cracks appeared in those zones which thermal stress concentrated, the thickness of recast layer is about 20μm and the taper and circularity were optimized at a laser power of 80-100W.

scholarly journals Determination of Plate Corrosion Dimension Using Nd:YAG Pulsed Laser-generated Wavefield and Experimental Dispersion Curves

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1436
Author(s):  
Kassahun Demissie Tola ◽  
Dai Quoc Tran ◽  
Byoungjoon Yu ◽  
Seunghee Park
Keyword(s):  
Laser Scanning ◽  
Pulsed Laser ◽  
Corrosion Damage ◽  
Dispersion Curves ◽  
Scanning System ◽  
Post Processing ◽  
Host Structure ◽  
Laser Scanning System ◽  
Experimental Dispersion

Corrosion detection using a pulsed laser scanning system can be performed via ultrasonic wave propagation imaging. This method outputs illustrations of the wave field within the host structure; thus, it can depict wave–corrosion area interactions. Additionally, post-processing can be performed to enhance the visualization of corroded areas. The wavefield energy computed using RMS (Root Mean Square) is a validated post-processing tool capable of displaying the location and area of corrosion-damaged regions. Nonetheless, to characterize corrosion, it is necessary to determine its depth. The measurement of depth in conjunction with that of the corroded area via the RMS distribution enables the determination of all dimensions of corrosion damage. Thereafter, the flaw severity can be evaluated. This study employed a wavefield within a plate on which corrosion was developed artificially to generate frequency–wavenumber dispersion curves. The curves were compared with their counterparts from a corrosion-free plate. Alternatively, they could be compared with dispersion curves drawn using the depth and material properties of a pristine plate via a computer program. Frequency–wavenumber pairs were extracted from the dispersion curves produced using the portion of the wavefield within the corroded area. These were inserted into the Rayleigh–Lamb equation, from which depths were calculated and averaged.

Software Enhanced Time Resolved Laser Assisted Device Alteration with a Non-Pulsed Laser Source

2009 ◽  
Author(s):  
Kent Erington ◽  
John Asquith ◽  
Dan Bodoh
Keyword(s):  
Temporal Resolution ◽  
Laser Scanning ◽  
Pulsed Laser ◽  
Laser Source ◽  
Scanning Microscope ◽  
Time Resolved ◽  
Laser Scanning Microscope ◽  
Timing Information ◽  
Custom Software

Abstract We describe a technique that is used to obtain timing information from laser assisted device alteration (LADA). The technique uses a non-pulsed laser scanning microscope to obtain timing information with a temporal resolution on the order of microseconds. Custom software is used to extract the timing information from the LADA images.

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