Novel adaptive single-beam laser vibrometer for vector surface-velocity measurement

1998 ◽  
Author(s):  
Marvin B. Klein ◽  
Gerald D. Bacher
Keyword(s):  
Velocity Measurement ◽  
Surface Velocity ◽  
Laser Vibrometer ◽  
Single Beam ◽  
Beam Laser

scholarly journals Characterization of dissimilar aluminum-copper material joining by controlled dual laser beam

2021 ◽  
Author(s):  
Joon Ho Cha ◽  
Hae Woon Choi
Keyword(s):  
Laser Beam ◽  
Power Distribution ◽  
Near Infrared ◽  
Weld Zone ◽  
Tensile Tests ◽  
Bead Width ◽  
Single Beam ◽  
The Core ◽  
Beam Laser ◽  
Dual Laser

Abstract Laser technology has many advantages in welding for the manufacture of EV battery packs. Aluminum (Al) and copper (Cu) are welded using a dual laser beam, suggesting the optimum power distribution for the core and ring beams. Due to the very high reflectance of Cu and Al exposed to near-infrared lasers, the material absorbs a very small amount of energy. Compared to single beam laser welding, dual beam welding has significantly improved surface quality by controlling surface solidification. The study focused on the quality of weld surface beads, weld properties and tensile strength by varying the output ratio of the core beam to the ring beam. Optimal conditions of Al6061 were a 700 W core beam, a 500 W ring beam and 200 mm/s of weld speed. For the C1020P, the optimum conditions were a center beam of 2500 W, a ring beam of 3000 W and a welding speed of 200 mm/s. In laser lap welding of Al-Al and Al-Cu, the bead width and the interfacial bead width of the joint increased as the output increased. The penetration depth did not change significantly, but small pores were formed at the interface of the junction. Tensile tests were performed to demonstrate the reliability of the weld zone, and computer simulations provided analysis of the heat distribution for optimal heat input conditions.

Comparison between Single & Multi Beam Laser Grooving of Low-K layers

2012 ◽  
Vol 2012 (1) ◽  
pp. 000433-000439 ◽  
Author(s):  
Jeroen van Borkulo ◽  
Rene Hendriks ◽  
Peter Dijkstra
Keyword(s):  
Laser Pulses ◽  
Efficient Manner ◽  
Single Beam ◽  
Performance Improvements ◽  
Technology Roadmap ◽  
Beam Laser ◽  
Hybrid Solutions ◽  
3D Packaging ◽  
Future Technologies ◽  
Low K

The traditional blade dicing technology has gone through an impressive evolution keeping up with quality, cost and miniaturization requirements that the semiconductor technology roadmaps introduced and specified. However, since wafer technologies have dropped below 90nm node and low k materials were introduced it became clear that blade dicing evolution came to an end and expensive hybrid solutions such as combined laser grooving processes and blade dicing technologies were required to achieve the desired product reliability. Similar situations have been seen with the ongoing trend to thinner wafer that are needed for miniaturization, 3D packaging and IC performance improvements. To achieve sufficient mechanical strength, complex dicing technologies and sequences have been introduced which do not respond to the requirements for current and near future technologies. This paper will discuss the low-k grooving process by laser pulses for IC wafers. The low-K laser grooving technology allows semiconductor manufacturers to execute the technology roadmap and continue to comply with Moore's law in an efficient manner. In specific this paper will elaborate on the comparison study made between the single beam and multi beam low-K grooving process. Together with a large IDM customer a comparison has been done to determine the results on quality, Heat Affected Zone (HAZ), productivity and yield.

Investigation of Fluid Flow and Heat Transfer in 3D Dual-Beam Laser Keyhole Welding

2010 ◽  
Author(s):  
Jun Zhou ◽  
Hai-Lung Tsai
Keyword(s):  
Heat Transfer ◽  
Laser Welding ◽  
Welding Process ◽  
Solidification Process ◽  
Melt Flow ◽  
Single Beam ◽  
Keyhole Welding ◽  
Beam Laser ◽  
Dual Beam ◽  
Laser Keyhole Welding

Dual-beam laser welding has become an emerging joining technique. Studies have demonstrated that it can provide benefits over conventional single-beam laser welding, such as increasing keyhole stability, slowing down cooling rate and delaying the humping onset to a higher welding speed. It is also reported to be able to improve weld quality significantly. However, due to its complexity the development of this promising technique has been limited to the trial-and-error procedure. In this study, mathematical models are developed to investigate the heat transfer, melt flow, and solidification process in three-dimensional dual-beam laser keyhole welding. Effects of key parameters, such as laser-beam configuration on melt flow, weld shape, and keyhole dynamics are studied. Some experimentally observed phenomena, such as the changes of the weld pool shape from oval to circle and from circle to oval during the welding process are analyzed in current study.

Single-beam atmospheric transverse velocity measurement

1978 ◽  
Vol 10 (3) ◽  
pp. 270-272 ◽  
Author(s):  
J. O'Shaughnessy ◽  
W. R. M. Pomeroy
Keyword(s):  
Velocity Measurement ◽  
Transverse Velocity ◽  
Single Beam

Multiple modes of laser-induced pattern formation in nanoscopic Co films

2006 ◽  
Vol 960 ◽  
Author(s):  
Christopher Favazza ◽  
Justin Trice ◽  
Radhakrishna Sureshkumar ◽  
Ramki Kalyanaraman
Keyword(s):  
Pattern Formation ◽  
Laser Intensity ◽  
Effective Means ◽  
Cost Effective ◽  
Range Order ◽  
Laser Interference ◽  
Pulse Laser Irradiation ◽  
Single Beam ◽  
Beam Laser ◽  
Selection Of

ABSTRACTDewetting instabilities in nanoscopic Co films, induced by uniform multiple ns pulse laser irradiation, leads to a system of nanoparticles with robust spatial order. On the other hand, irradiation by non-uniform laser intensity, such as with a two beam laser interference pattern generates a quasi two-dimensional pattern of nanoparticles possessing long range order (LRO) and short range order (SRO). Here we discuss the various instabilities that are responsible for the production of these dissimilar patterns and length scales on the basis of their time scales. For the case of single beam irradiation, the film progresses in a manner that can be attributed to classical spinodal dewetting. Pattern formation from interference irradiation is the result of time scale-based selection of competing processes, which can be chosen by controlling the film thickness. This approach promises a simple and cost-effective means to self-assemble various nanostructures.

Structural health monitoring–based methodologies for managing uncertainty in aircraft structural life assessment

2014 ◽  
Vol 13 (6) ◽  
pp. 621-628 ◽  
Author(s):  
Ray Bond ◽  
Sara Underwood ◽  
Douglas E Adams ◽  
Joshua J Cummins
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Life Assessment ◽  
Surface Velocity ◽  
Identification System ◽  
Laser Vibrometer ◽  
Aircraft Maintenance ◽  
Labor Costs ◽  
Inspection Method ◽  
Structural Health

Aircraft maintenance approaches that rely on only scheduled inspections have an intrinsic amount of uncertainty and risk because intervals do not reflect the loading and damage history of individual aircraft. This risk is more pronounced in composite aircraft, because damage is often not visually apparent. This work presents two case studies of complementary structural health monitoring methods that are designed to reduce the risk in aircraft maintenance, as well as the cost of frequent, lengthy inspections. The first is an impact identification system which is capable of locating impacts to a full-scale fuselage using only three sensors. This impact identification method is able to quantify the severity of impacts, allowing maintenance personnel to focus inspections on areas that have sustained frequent and/or high-amplitude impacts. Using this method, over 97% of impacts to a heavy-lift helicopter fuselage are located within 9 in of the true impact location. The second case study details the development of a noncontact wide-area inspection method, which has the potential to reduce inspection times and uncertainty as compared to labor-intensive inspection methods such as coin tap testing. This inspection method exploits the nonlinear forced vibration characteristics of damaged areas through surface velocity measurements acquired by a scanning laser vibrometer. By comparing the structure’s response to forcing functions of differing magnitudes, the local nonlinear characteristics of damage are identified. This automated inspection method is shown to be effective in locating subsurface damage in composite helicopter panels and has the potential to reduce both labor costs and damage detection uncertainty.

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