Using Diffractive Optical Elements

Katz, Shlomit; Kaplan, Natan; Grossinger, Israel

doi:10.1002/latj.201800021

Cited by 16 publications

(7 citation statements)

References 1 publication

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“…Second, we assume a melting strategy with short melt lines or modified beam shapes by diffractive optical elements. [67,68] In this case, the beam absorption occurs in a broader range of temperatures because the laser beam is often absorbed in solid material, namely, the powder bed. The electrical resistivity of almost all alloys changes significantly at the transition point from solid to liquid.…”

Section: Melt Pool Depth For Different Rmentioning

confidence: 99%

Modeling Laser Beam Absorption of Metal Alloys at High Temperatures for Selective Laser Melting

et al. 2021

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Selective Laser Melting (SLM) is a promising technology to fabricate metallic components with complex geometries. However, determining process windows for specific materials and SLM machines by trial‐and‐error experiments is time consuming and expensive. Numerical simulation has been demonstrated as an efficient way to aid the process development. A crucial aspect is the absorption and reflection of the laser by the material. While there exist elaborated ray tracing approaches and absorption models, the most important drawback is to measure a reliable reflection coefficient of the material for different temperatures and phases. In this work, we discuss the application of a laser beam absorption model for SLM of metal alloys in the high temperature regime. The model bases on fundamental physical laws by taking reflection, refraction and absorption into account. The corresponding reflection coefficient is related to other physical quantities, like the electrical resistivity. The computed reflection coefficients are compared with reflection coefficient measurements of liquid NiFe alloys and with SLM of stainless steel 316L and Ti–6Al–4V. Finally, the laser beam absorption model is implemented in SAMPLE2D, a software for simulation of additive manufacturing on the powder scale, and is exemplary applied on single track melting experiments on compact Ti–6Al–4V plates.

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Section: Melt Pool Depth For Different Rmentioning

confidence: 99%

Modeling Laser Beam Absorption of Metal Alloys at High Temperatures for Selective Laser Melting

et al. 2021

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“…This optical element, also called a Diffractive Optical Element (DOE), is necessary to ameliorate the temperature homogeneity at the sample surface. Indeed the natural beam power shape is nearly a 2D Gaussian curve [30], meaning that the periphery of a disk sample will receive less power than the centre. The DOE employed (Holo/or Ltd., Rehovot, Israel, model RH-217-K-Y-A tailored for our laser wavelength) allows to transform the beam power profile to a round "top-hat" shape [30].…”

Section: Laser Heating and Temperature Controlmentioning

confidence: 99%

“…Indeed the natural beam power shape is nearly a 2D Gaussian curve [30], meaning that the periphery of a disk sample will receive less power than the centre. The DOE employed (Holo/or Ltd., Rehovot, Israel, model RH-217-K-Y-A tailored for our laser wavelength) allows to transform the beam power profile to a round "top-hat" shape [30]. Temperature homogeneity increasing with the use of such DOE is evidenced by Figure 5.…”

Section: Laser Heating and Temperature Controlmentioning

confidence: 99%

A new thermo-desorption laser-heating setup for studying noble gas diffusion and release from materials at high temperatures

Horlait

Faure

Thomas

et al. 2021

Review of Scientific Instruments

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A new heating and gas treatment line for Thermo-Desorption Spectrometry (TDS) of noble gases (He, Ne, Ar, Kr and Xe) is presented. It was built with the primary objective to offer advanced temperature controls and capabilities while working in a cold-environment. By choosing a high-power continuous wave laser as an heating source, and using a Proportional-Integral-Derivative (PID) controller system, noble gases TDS can now be performed with fast and highly steady heating ramps (e.g. less than 1°C deviation from setpoint for ≤ 1°C.s -1 ramps). Sample temperature over 2000°C can also routinely be reached, with limited heating of the sample support and the sample chamber, offering the possibility to have several samples awaiting in the ultra-high vacuum chamber. We also present development efforts made to increase temperature homogeneity of the heated sample while limiting contacts with the sample holder.Recent results acquired with this TDS setup on krypton thermal diffusion in uranium dioxide (UO 2 ) as a function of O 2 additions are also presented as an application example.

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“…Profiling multiple laser beams on a single image sensor has become increasingly important due to the growing number of multi-beam applications. Spatial light modulators [1], for example, can create multiple, dynamically controlled laser beamsused for optical tweezer arrays in cold atom experiments [2][3][4] and multi-site neuron activation in two-photon microscopy [5]while diffractive optical elements allow multiple beams to be created for machining applications [6,7] and can also form laser beam arrays used in medical skin treatment procedures [8,9].…”

Section: Introductionmentioning

confidence: 99%

Measuring laser beams with a neural network

Hofer¹,

Milan²,

Smith³

2022

Appl. Opt.

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A deep neural network (NN) is used to simultaneously detect laser beams in images and measure their center coordinates, radii and angular orientations. A dataset of images containing simulated laser beams and a dataset of images with experimental laser beamsgenerated using a spatial light modulator-are used to train and evaluate the NN. After training on the simulated dataset the NN achieves beam parameter rootmean-square-errors (RMSEs) of less than 3.4% on the experimental dataset. Subsequent training on the experimental dataset causes the RMSEs to fall below 1.1%. The NN method can be used as a stand-alone measurement of the beam parameters or can compliment other beam profiling methods by providing an accurate region-of-interest.

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Using Diffractive Optical Elements

Cited by 16 publications

References 1 publication

Modeling Laser Beam Absorption of Metal Alloys at High Temperatures for Selective Laser Melting

Modeling Laser Beam Absorption of Metal Alloys at High Temperatures for Selective Laser Melting

A new thermo-desorption laser-heating setup for studying noble gas diffusion and release from materials at high temperatures

Measuring laser beams with a neural network

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