Evaporative Cutting of a Semitransparent Body With a Moving CW Laser

1988 ◽  
Vol 110 (4a) ◽  
pp. 924-930 ◽  
Author(s):  
H. Abakians ◽  
M. F. Modest
Keyword(s):  
Laser Beam ◽  
Integral Method ◽  
Continuous Wave ◽  
Nonlinear Partial Differential Equations ◽  
Groove Depth ◽  
Surface Heat ◽  
Heat Losses ◽  
Gaussian Laser Beam ◽  
Cw Laser ◽  
Partial Evaporation

The formation of a groove by partial evaporation of a moving semi-infinite and semitransparent solid is considered. Evaporative removal of material is achieved by focusing a high-power, highly concentrated Gaussian laser beam of continuous wave (CW) onto the surface of the solid. Surface heat losses due to radiation and convection are assumed to be negligible, and conductive losses are treated in an approximate fashion using a simple integral method. The relevant nonlinear partial differential equations are solved numerically, and results for groove depth and shape are presented for a variety of laser and solid parameters.

Evaporative Cutting of a Semi-infinite Body With a Moving CW Laser

1986 ◽  
Vol 108 (3) ◽  
pp. 602-607 ◽  
Author(s):  
M. F. Modest ◽  
H. Abakians
Keyword(s):  
Partial Differential Equations ◽  
Laser Beam ◽  
High Power ◽  
Integral Method ◽  
Nonlinear Partial Differential Equations ◽  
Groove Depth ◽  
Gaussian Laser Beam ◽  
Infinite Body ◽  
Cw Laser ◽  
Deep Groove

The formation of a deep groove by evaporation on a moving semi-infinite solid is considered. Evaporative removal of material is achieved by focusing a high-power, highly concentrated Gaussian laser beam of constant wattage (CW laser) onto the surface of the solid. Assuming thermal losses due to conduction and convection to be relatively minor, these losses are treated in an approximate fashion using a simple integral method. The relevant nonlinear partial differential equations are solved numerically, and results for groove depth and shape are presented for a variety of laser and solid parameters.

scholarly journals Dual Laser Beam Asynchronous Dicing of 4H-SiC Wafer

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1331
Author(s):  
Zhe Zhang ◽  
Zhidong Wen ◽  
Haiyan Shi ◽  
Qi Song ◽  
Ziye Xu ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Laser Beam ◽  
Continuous Wave ◽  
Fe Model ◽  
Cw Laser ◽  
Thermal Stress Field ◽  
Simulation And Experiment ◽  
Mechanical Breaking ◽  
Sic Wafer ◽  
Dual Laser

SiC wafers, due to their hardness and brittleness, suffer from a low feed rate and a high failure rate during the dicing process. In this study, a novel dual laser beam asynchronous dicing method (DBAD) is proposed to improve the cutting quality of SiC wafers, where a pulsed laser is firstly used to introduce several layers of micro-cracks inside the wafer, along the designed dicing line, then a continuous wave (CW) laser is used to generate thermal stress around cracks, and, finally, the wafer is separated. A finite-element (FE) model was applied to analyze the behavior of CW laser heating and the evolution of the thermal stress field. Through experiments, SiC samples, with a thickness of 200 μm, were cut and analyzed, and the effect of the changing of continuous laser power on the DBAD system was also studied. According to the simulation and experiment results, the effectiveness of the DBAD method is certified. There is no more edge breakage because of the absence of the mechanical breaking process compared with traditional stealth dicing. The novel method can be adapted to the cutting of hard-brittle materials. Specifically for materials thinner than 200 μm, the breaking process in the traditional SiC dicing process can be omitted. It is indicated that the dual laser beam asynchronous dicing method has a great engineering potential for future SiC wafer dicing applications.

Continuous-wave laser-induced diffusion in silicon

1985 ◽  
Vol 63 (6) ◽  
pp. 886-889
Author(s):  
P. Schvan ◽  
R. E. Thomas
Keyword(s):  
Laser Beam ◽  
High Speed ◽  
Continuous Wave ◽  
Scanning Speed ◽  
Processing Technique ◽  
Continuous Wave Laser ◽  
Large Area ◽  
Incident Laser Power ◽  
Cw Laser ◽  
Novel Processing

A novel processing technique to form shallow p-n junctions using a continuous-wave (cw) laser beam scanned over a large area is described. The results of computer simulation of the heat-flow problem were used to find the optimum condition for cw laser-induced liquid-phase diffusion. High-speed scanning of the laser beam and the application of phosphosilica glass as a diffusion source, which also acts as an antireflective coat, are essential parts of the process. The optimum incident laser power was around 7.5 W with a scanning speed of 100 cm/s. This process produced junction depths of around 0.2–0.4 μm. Reliable contacts to the shallow diffusions were made using tungsten silicide formed prior to the aluminum deposition. The p-n junctions formed by this technique showed good diode characteristics with breakdown voltages over 35 V and leakage current around 10−5 A/cm2.

Targeting of the retinal pigment epithelium (RPE) by means of a rapidly scanned continuous wave (CW) laser beam

2003 ◽  
Vol 32 (4) ◽  
pp. 252-264 ◽  
Author(s):  
Ralf Brinkmann ◽  
Norbert Koop ◽  
Mustafa Özdemir ◽  
Clemens Alt ◽  
Georg Schüle ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Laser Beam ◽  
Continuous Wave ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Cw Laser

Laser Timing Probe with Frequency Mapping for Locating Signal Maxima

2009 ◽  
Author(s):  
L.S. Koh ◽  
H. Marks ◽  
L.K. Ross ◽  
C.M. Chua ◽  
J.C.H. Phang
Keyword(s):  
Response Time ◽  
Continuous Wave ◽  
Single Point ◽  
Point Measurement ◽  
Cw Laser ◽  
Measurement Capabilities

Abstract A Laser Timing Probe (LTP) system which uses a noninvasive 1.3 µm continuous wave (CW) laser with frequency mapping and single point measurement capabilities is described. The frequency mapping modes facilitate the localization of signal maxima for subsequent single point measurements. Measurements of waveforms with long delays and 50 ps response time from NMOS and PMOS transistors are also shown.

Self-focusing of cosh-Gaussian laser beam in collisional plasma: effect of nonlinear absorption

2021 ◽  
Author(s):  
Naveen Gupta ◽  
Sandeep Kumar ◽  
A Gnaneshwaran ◽  
Sanjeev Kumar ◽  
Suman Choudhry
Keyword(s):  
Laser Beam ◽  
Nonlinear Absorption ◽  
Collisional Plasma ◽  
Gaussian Laser Beam ◽  
Self Focusing ◽  
Plasma Effect

scholarly journals Thin-Film Processing of Polypropylene and Polystyrene Sheets by a Continuous Wave CO2 Laser with the Cu Cooling Base

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1448
Author(s):  
Nobukazu Kameyama ◽  
Hiroki Yoshida ◽  
Hitoshi Fukagawa ◽  
Kotaro Yamada ◽  
Mitsutaka Fukuda
Keyword(s):  
Thin Film ◽  
Co2 Laser ◽  
Continuous Wave ◽  
Cw Laser ◽  
Heat Effects ◽  
Film Processing ◽  
Carbon Dioxide Co2 ◽  
A Minor ◽  
Residual Heat ◽  
Thin Film Processing

Carbon dioxide (CO2) laser is widely used in commercial and industrial fields to process various materials including polymers, most of which have high absorptivity in infrared spectrum. Thin-film processing by the continuous wave (CW) laser is difficult since polymers are deformed and damaged by the residual heat. We developed the new method to make polypropylene (PP) and polystyrene (PS) sheets thin. The sheets are pressed to a Cu base by extracting air between the sheets and the base during laser processing. It realizes to cut the sheets to around 50 µm thick with less heat effects on the backside which are inevitable for thermal processing using the CW laser. It is considered that the boundary between the sheets and the base is in thermal equilibrium and the base prevents the sheets from deforming to support the backside. The method is applicable to practical use since it does not need any complex controls and is easy to install to an existing equipment with a minor change of the stage.

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