scholarly journals Multiscale Stereolithography Using Shaped Beams

2017 ◽  
Vol 5 (4) ◽  
Author(s):  
Huachao Mao ◽  
Yuen-Shan Leung ◽  
Yuanrui Li ◽  
Pan Hu ◽  
Wei Wu ◽  
...  
Keyword(s):  
Laser Beam ◽  
Tool Path ◽  
Three Dimensional ◽  
Laser Beams ◽  
Laser Exposure ◽  
Beam Size ◽  
Scale Level ◽  
3D Objects ◽  
Good Surface ◽  
Single Scale

Current stereolithography (SL) can fabricate three-dimensional (3D) objects in a single-scale level, e.g., printing macroscale or microscale objects. However, it is difficult for the SL printers to fabricate a 3D macroscale object with microscale features. In the paper, a novel SL-based multiscale fabrication method is presented to address such a problem. The developed SL process can fabricate multiscale features by dynamically changing the shape and size of a laser beam. Different shaped beams are realized by switching apertures with different micropatterns. The laser beam without using micropatterns is used to fabricate macroscale features, while the shaped laser beams based on small apertures are used to fabricate micropatterned features. Accordingly, a tool path planning method for the multiscale fabrication process is presented to build macroscale and microscale features using different layer thicknesses, laser exposure time, and scanning paths. Compared with the conventional SL process using a fixed laser beam size, our process can manufacture multiscale features in a 3D object with fast fabrication speed and good surface quality.

Multi-Scale Stereolithography Using Shaped Beams

2017 ◽  
Author(s):  
Huachao Mao ◽  
Yuen-Shan Leung ◽  
Yuanrui Li ◽  
Pan Hu ◽  
Wei Wu ◽  
...  
Keyword(s):  
Laser Beam ◽  
Tool Path ◽  
Three Dimensional ◽  
Laser Exposure ◽  
Micro Scale ◽  
Multi Scale ◽  
Good Surface ◽  
Single Scale ◽  
Macro Scale ◽  
Micro Patterns

Current Stereolithography (SL) can fabricate three-dimensional (3D) objects in a single scale level, e.g. printing macro-scale or micro-scale objects. However, it is difficult for the SL printers to fabricate a 3D macro-scale object with micro-scale features. In the paper a novel SL-based multi-scale fabrication method is presented to address such a problem. The developed SL process can fabricate multi-scale features by dynamically changing the shape and size of a laser beam. Different shaped beams are realized by switching apertures with different micro-patterns. The laser beam without using any micro-patterns is used to fabricate the macro-scale features, while the shaped laser beams with smaller sizes are used to fabricate micro-patterned features. Accordingly, the tool path planning method for the multi-scale fabrication process are developed so that macro-scale and micro-scale features can be built by using different layer thicknesses, laser exposure time, and scanning paths. Compared with the conventional SL process based on a fixed laser beam size, our process can fabricate multi-scale features in a 3D object. It also has fast fabrication speed and good surface quality.

scholarly journals A critical look at the prediction of the temperature field around a laser-induced melt pool on metallic substrates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yi Shu ◽  
Daniel Galles ◽  
Ottman A. Tertuliano ◽  
Brandon A. McWilliams ◽  
Nancy Yang ◽  
...  
Keyword(s):  
Laser Beam ◽  
Constant Velocity ◽  
Three Dimensional ◽  
Laser Beams ◽  
Poor Control ◽  
Metallic Substrates ◽  
Melt Pool ◽  
Mechanical Models ◽  
Transport Effects ◽  
Thermal Histories

AbstractThe study of microstructure evolution in additive manufacturing of metals would be aided by knowing the thermal history. Since temperature measurements beneath the surface are difficult, estimates are obtained from computational thermo-mechanical models calibrated against traces left in the sample revealed after etching, such as the trace of the melt pool boundary. Here we examine the question of how reliable thermal histories computed from a model that reproduces the melt pool trace are. To this end, we perform experiments in which one of two different laser beams moves with constant velocity and power over a substrate of 17-4PH SS or Ti-6Al-4V, with low enough power to avoid generating a keyhole. We find that thermal histories appear to be reliably computed provided that (a) the power density distribution of the laser beam over the substrate is well characterized, and (b) convective heat transport effects are accounted for. Poor control of the laser beam leads to potentially multiple three-dimensional melt pool shapes compatible with the melt pool trace, and therefore to multiple potential thermal histories. Ignoring convective effects leads to results that are inconsistent with experiments, even for the mild melt pools here.

Characterization of “Bulk Lithography” Process for Fabrication of Three-Dimensional Microstructures

2013 ◽  
Vol 1 (4) ◽  
Author(s):  
Prasanna Gandhi ◽  
Kiran Bhole
Keyword(s):  
Laser Beam ◽  
Spatial Variation ◽  
Three Dimensional ◽  
Single Layer ◽  
Exposure Dose ◽  
Laser Exposure ◽  
Experimental Characterization ◽  
Gaussian Laser Beam ◽  
Lithography Process

Various ways of fabricating a three-dimensional (3D) component in a single-layer exposure using spatial variation of exposure dose have been presented in the literature. While some of them are based on dynamic mask process, more recently, a process based on varying intensity of a scanning Gaussian laser beam termed as “bulk lithography” has been proposed. In bulk lithography, the entire varying depth 3D microstructure gets fabricated because of spatial variation of intensity of laser imposed at every point in single layer scan. For the bulk lithography process, this paper first presents experimental characterization of unconstrained depth photopolymerization of resin upon exposure to Gaussian laser beam. Experimental characterization carried out for two resins systems: namely 1,6 hexane diol-diacrylate (HDDA) and trimethylolpropane triacrylate (TMPTA), over relatively wider range of Ar+ laser exposure dose and time, show behavior well beyond Beer–Lambert law. A unified empirical model is proposed to represent the nondimensional depth variation with respect to the time and energy of exposure for both resins. Finally, using these models, successful fabrication of several microstructures including micro-Fresnel lens, textured curved surface, otherwise difficult or impossible to fabricate, is demonstrated. Several advantages of the bulk lithography as compared to other similar processes in the literature are highlighted.

scholarly journals Field structure and electron acceleration in a slit laser beam

2010 ◽  
Vol 28 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Y.J. Xie ◽  
W. Wang ◽  
L. Zheng ◽  
X.P. Zhang ◽  
Q. Kong ◽  
...  
Keyword(s):  
Laser Beam ◽  
Electric Field Intensity ◽  
Three Dimensional ◽  
Field Structure ◽  
Particle Simulation ◽  
Laser Beams ◽  
Net Energy ◽  
Incoming Momentum ◽  
Net Energy Gain ◽  
Field Intensity Distribution

AbstractThe electric field intensity distribution and the phase velocity distribution of a slit in laser beams with different parameters are analyzed. Using three-dimensional test particle simulation, the laser beam with a slit induced acceleration of electrons with different initial momenta is investigated. Contrary to anticipation, the maximum net energy gain is not monotone increasing as the incoming momentum increasing. Based on the field structure and analysis, we gave an explanation for this.

Generating Robot Trajectories for Conformal Three-Dimensional Printing Using Nonplanar Layers

2019 ◽  
Vol 19 (3) ◽  
Author(s):  
Aniruddha V. Shembekar ◽  
Yeo Jung Yoon ◽  
Alec Kanyuck ◽  
Satyandra K. Gupta
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Industrial Robots ◽  
Robot Arm ◽  
Three Dimensional Printing ◽  
Six Degrees Of Freedom ◽  
3D Objects ◽  
Good Surface ◽  
Material Deposition ◽  
Good Surface Finish

Additive manufacturing (AM) technologies have been widely used to fabricate three-dimensional (3D) objects quickly and cost-effectively. However, building parts consisting of complex geometries with curvatures can be a challenging process for the traditional AM system whose capability is restricted to planar layered printing. Using six degrees-of-freedom (DOF) industrial robots for AM overcomes this limitation by allowing the material deposition to take place on nonplanar surfaces. In this paper, we present trajectory planning algorithms for 3D printing using nonplanar material deposition. Trajectory parameters are selected to avoid collision with printing surface and satisfy robot constraints. We have implemented our approach by using a 6DOF robot arm. The complex 3D structures with various curvatures were successfully fabricated with a good surface finish.

scholarly journals Investigation of serial coherent laser beam combination based on Brillouin amplification

2007 ◽  
Vol 25 (1) ◽  
pp. 79-83 ◽  
Author(s):  
SHUANGYI WANG ◽  
ZHIWEI LÜ ◽  
DIANYANG LIN ◽  
LEI DING ◽  
DONGBIN JIANG
Keyword(s):  
Laser Beam ◽  
High Power ◽  
Simple Structure ◽  
Low Cost ◽  
Coupling Efficiency ◽  
Laser Beams ◽  
Beam Combination ◽  
Multiple Beams ◽  
Combination Scheme ◽  
Stokes Beam

Based on transferring energy from multiple pump beams into one Stokes beam using Brillouin amplification, a serial coherent laser beam combination scheme is presented, which has many advantages, such as, simple structure, low cost, ease of adjustment, higher load capability, scalable easily, etc. Furthermore, it has been demonstrated that the combination of several beams using this method is theoretically possible. But in practice, the amplification of high power Stokes beam is a key problem to solve. In this paper, the amplification of Stokes beam whose power is higher than the pump beam is first studied and proved experimentally. Coupling the two laser beams by this method is proved experimentally, and the coupling efficiency reaches more than 80%. Then the feasibility of multiple beams combination based on Brillouin amplification is analyzed and tested theoretically.

Tool Path Optimization of 2D Contour Considering Stock Boundary

2012 ◽  
Vol 251 ◽  
pp. 169-172
Author(s):  
Fu Zhong Wu
Keyword(s):  
Present Method ◽  
Tool Path ◽  
Three Dimensional ◽  
Boundary Curve ◽  
Tool Path Generation ◽  
Path Optimization ◽  
Path Generation ◽  
Offset Curves ◽  
Measuring Machine ◽  
Tool Diameter

Based on analyzing the existing algorithms, a novel tool path generation of 2D contour considering stock boundary is presented. Firstly the boundary points of stock are obtained by three-dimensional measuring machine. And the boundary curve is constructed by method of features identifying. The stock boundary is offset toward outside with tool diameter. An enclosed region is formed between the contour curves and the offset curves of stock boundary. The tool path is generated by form of parallel spiral by offsetting the stock boundary in the enclosed region. Finally the validity of present method is demonstrated by an example.

Laser Beam Steering Along Three-Dimensional Paths

2018 ◽  
Vol 23 (3) ◽  
pp. 1148-1158 ◽  
Author(s):  
Brahim Tamadazte ◽  
Rupert Renevier ◽  
Jean-Antoine Seon ◽  
Andrey V. Kudryavtsev ◽  
Nicolas Andreff
Keyword(s):  
Laser Beam ◽  
Beam Steering ◽  
Three Dimensional

Relativistic self-focusing of a rippled laser beam in a plasma

1999 ◽  
Vol 62 (4) ◽  
pp. 389-396 ◽  
Author(s):  
M. V. ASTHANA ◽  
A. GIULIETTI ◽  
DINESH VARSHNEY ◽  
M. S. SODHA
Keyword(s):  
Refractive Index ◽  
Laser Beam ◽  
The Self ◽  
Laser Beams ◽  
Radial Dependence ◽  
Main Beam ◽  
Gaussian Laser Beam ◽  
Self Focusing ◽  
Saturation Effects ◽  
Paraxial Ray

This paper presents an analysis of the relativistic self-focusing of a rippled Gaussian laser beam in a plasma. Considering the nonlinearity as arising owing to relativistic variation of mass, and following the WKB and paraxial-ray approximations, the phenomenon of self-focusing of rippled laser beams is studied for arbitrary magnitude of nonlinearity. Pandey et al. [Phys. Fluids82, 1221 (1990)] have shown that a small ripple on the axis of the main beam grows very rapidly with distance of propagation as compared with the self-focusing of the main beam. Based on this analogy, we have analysed relativistic self-focusing of rippled beams in plasmas. The relativistic intensities with saturation effects of nonlinearity allow the nonlinear refractive index in the paraxial regime to have a slower radial dependence, and thus the ripple extracts relatively less energy from its neighbourhood.

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