United States

The spatial laser energy absorption inside the keyhole is decisive for the dynamic molten pool behaviors and the resultant weld properties in high-power laser beam welding. In this paper, a numerical simulation of the LBW process, considering the 3D transient heat transfer, fluid flow and keyhole dynamics, is implemented, in which the free surface is tracked by the volume-of-fluid algorithm. The underlying laser-material interactions i.e., the multiple reflections and Fresnel absorption, are considered by an advanced ray-tracing method based on a localized Level-Set strategy. The laser energy absorption is analyzed from a time-averaged point of view for a better statistical representation. It is found for the first time that a noticeable drop of the time-averaged laser energy absorption occurs at the focal position of the laser beam, and the rest region of the keyhole has relatively homogenous absorbed energy. This unique absorption pattern may lead to a certain keyhole instability and have a strong correlation with the detrimental narrowing phenomenon in the molten pool. The influence of the different focal positions of the laser beam on the keyhole dynamics and weld pool profile is also analyzed and compared. The obtained numerical results are compared with experimental measurements to assure the validity of the proposed model.

ICALEO 2023

The Influence of the Spatial Laser Energy Absorption of the Molten Pool Dynamics In High-Power Laser Beam Welding

numerical modelling

keyhole dynamics

laser energy absorption

laser beam welding

molten pool

#### Welcome to the 43rd annual ICALEO!

Attention laser enthusiasts, innovators, and industry leaders! Get ready to immerse yourself in the exciting world of lasers at the 43rd annual ICALEO conference. This year, we gathered in the iconic city of Hollywood, California, for cutting-edge technology, groundbreaking presentations, and unparalleled networking opportunities.
Whether you're a seasoned professional or new to the field of photonics, the 43rd annual ICALEO had something for everyone. 

#### General Chair Welcome Message

It is with immense joy and anticipation that I extend a warm welcome to each and every one of you as the General Chair of this year's ICALEO conference.

This year, we find ourselves in the iconic setting of Hollywood, serving as a fitting backdrop for the extraordinary developments in laser technology and applications unfolding in our community.

Our main sessions cover a diverse range of topics, from the intricacies of micro and nano processing to the transformative power of laser additive manufacturing. We will explore the frontiers of battery technology, delve into the intricate world of artificial intelligence, and witness the seamless integration of lasers into these realms.

For those joining us for the first time, we extend an especially heartfelt welcome. ICALEO is not just a conference; it's a convergence of minds, ideas, and innovations. Beyond the formal sessions, I encourage you to engage in informal exchanges. The spirit of discovery and camaraderie is as much a part of the ICALEO experience as the scheduled sessions.

Thank you for being a part of ICALEO 2024. Whether you are a returning participant or a first-time attendee, your presence adds immeasurable value to our vibrant community. May this conference be, this year again, a catalyst for inspiration, collaboration, and breakthroughs that will resonate in our community and beyond.

Eric Mottay 
Congress General Chair, ICALEO 2024


#### About LIA

The Laser Institute of America (LIA) is the professional society for laser applications and safety. Our mission is to foster lasers, laser applications, and laser safety worldwide. Serving the industrial, medical, research and government communities for over 50 years, LIA offers technical information, training and networking opportunities to laser users
from around the globe.

#### About LIA Conferences

The conferences of the Laser Institute of America are the town square of the laser community. A large and diverse group, laser professionals often find themselves disconnected from each other. LIA conferences, however, bring the university researcher, the business executive and the production floor user together under one roof for a unique and
rewarding networking opportunity.

#### Program Tracks
Below is the list of all tracks that were on ICALEO 2024 Conference.

##### Laser Additive Manufacturing
* The Laser Additive Manufacturing (LAM) track is a forum to explore the latest innovations and research in laser-based additive manufacturing (LAM). The Laser Additive Manufacturing track focuses on diverse topics, including laser-based powder bed fusion (PBF-LB), directed energy deposition (DED), and other emerging techniques revolutionizing modern manufacturing processes. From materials science to process optimization, from design innovation to industrial implementation, this track connects researchers, engineers, and industry leaders to exchange insights and share breakthroughs in laser additive manufacturing.

##### Laser Materials Macroprocessing
* The Macroprocessing track comprises some of the most productive laser processing applications. Although these applications have been broadly adopted, researchers and industry are persistently innovating to provide new techniques and novel technologies to advance macro materials processing. The attendees will share and discuss those exciting achievements of their research with peers in these macroscopic specialized sessions.

##### Laser Materials Microprocessing
* The Microprocessing track will consist of papers and talks featuring a wide spectrum of applications and innovative equipment for materials processing in microscales with a strong focus on processes with Short and Ultrashort Pulsed Lasers. The presentations will introduce the latest and greatest advancements in their respective fields, presented by world-leading companies and research organizations. This year we will have talks around the headlines of “Beam shaping”, “Glass”, “Surface processing” and “Drilling” between other topics.

##### Frontiers in Laser Applications
* The Frontier in Laser Applications (FLA) track explores recent, cutting-edge applications of lasers, highlighting innovation at the transition of research and industry. The track has included presentations from a variety of fields: Novel 3-D Printing, Advanced Manufacturing, Laser Manufactured Devices, and Frontiers in Laser Processing. The sessions under the Frontier in Laser Application track promise to bring diverse and unique perspectives from real-world applications across laser manufacturing.

##### Laser in Battery Manufacturing
* Electrification is crucial to address global environmental challenges. The laser plays a key role in most manufacturing steps in battery production with all possible laser applications from ablation, structuring, welding, cutting, and marking. Further improvements in the batteries’ power densities, fast charging properties, and yield in battery production are related to photonics and, thus, lasers. We will hear and discuss the latest developments in research, development, and industrial applications. Join us for this year’s Battery Track.

##### Artifical Intelligence in Laser Processing
* The track ‘Artificial Intelligence in Laser Processing’ at ICALEO 2024 explores the fusion of AI and laser manufacturing. Discover cutting-edge research on optimizing laser processes and enhancing manufacturing efficiency. Explore AI’s diverse applications in parameter optimization, quality prediction, real-time process monitoring, and control. Join us to unlock the potential of AI-driven solutions revolutionizing laser materials processing, delivering unprecedented precision, productivity, and innovation.

You need to log in with the email address you registered with. Access credentials have been sent to your email. 

Please be sure to check your spam and other email folders if you do not see an email confirmation right away.

Please log in to explore this event.

It looks like you are not registered for this event. To access the site please register [**here**](https://icaleo.org/attend). 

Are you an LIA Member? Find a special discount code in your LIA account at https://www.lia.org/user to apply to your registration for additional savings!

Please register!

ICALEO 2024

Attention laser enthusiasts, innovators, and industry leaders! Get ready to immerse yourself in the exciting world of lasers at the 43rd annual ICALEO conference. 

technical paper

**General Chair Welcome**

![](https://assets.underline.io/markdown_image/1/image/d6e6dddc08bf2371b9136ea9c18dc5ab.png)              

Welcome to ICALEO® 2023!
	
We were excited to host the world’s leading international conference on Lasers and Electro-Optics in Chicago. The Laser has been shown to have the potential to revolutionize solutions for major global challenges like energy usage and supply, global warming, and CO2 footprint. Even the fusion energy breakthrough is based on laser technology. The conference, with peer-reviewed scientific and technical presentations, focused on the newest results in Micro Applications, Macro Applications, Additive Manufacturing, Beam Shaping and Frontiers in Laser Applications. Additionally, the Battery-Manufacturing Track gave an overview of the process combined with the newest advances in laser application results. 

The Business Session brought the business aspect and environment of the laser to the audience and the possibility to discuss with seasoned industry leaders from around the world. 

Whether this is the first time you are hearing about ICALEO or you are a longtime attendee, you will find something of interest, new ideas, and an excellent opportunity to network with other laser specialists worldwide. 

**Klaus Löffler **  
ICALEO General Chair   
Managing Director, Precitec GmbH

**What is ICALEO?**

ICALEO® brings together the brightest minds, seasoned professionals, and pioneering researchers from around the world. With a laser-focused agenda, ICALEO offers an exceptional platform to delve into the cutting-edge advancements, diverse applications, and transformative research that define lasers and electro-optics.

Participants will be immersed in a dynamic environment that fosters collaborative learning, networking, and idea exchange. Through engaging plenary presentations, technical sessions, an industry business panel, and networking events, attendees gain insights into the forefront of laser technology. From industrial applications to medical breakthroughs, additive manufacturing to materials processing, ICALEO covers the entire spectrum of laser-related disciplines. Moreover, the event serves as a launching pad for synergistic partnerships, paving the way for professionals to forge connections that shape the future of our industry.

Join us in Chicago and be part of an unparalleled gathering that challenges the boundaries of possibility within lasers and electro-optics. As we convene to share knowledge, explore innovations, and cultivate collaborations, ICALEO stands as a pivotal force driving the evolution of this transformative technology.

**Who attended?**

ICALEO is tailor-made for professionals, researchers, academics, and enthusiasts who are deeply passionate about the world of lasers and electro-optics. If you're an industry trailblazer, an academic luminary, an aspiring expert, or a postgraduate student looking to dive into the latest developments and trends, this is an event you won't want to miss.

Industrial leaders seeking to stay ahead of the curve in their fields, engineers working on laser applications, and manufacturing experts interested in additive manufacturing and materials processing will find ICALEO to be an invaluable platform. Researchers and scientists exploring the forefront of laser technology, from fundamental principles to groundbreaking applications, will also discover a wealth of knowledge and networking opportunities.

Medical professionals investigating laser-based medical advancements, entrepreneurs seeking to innovate with lasers, educators aiming to stay updated with the latest in laser education, and policy makers shaping the industry's landscape are all essential attendees. Whether you're an established expert or a rising star, the 42nd annual ICALEO promises to offer a diverse ecosystem of expertise, connections, and knowledge sharing that caters to the laser and electro-optics communities.

**Fields Represented:**

* Entrepreneurs and Innovators
* Manufacturing Experts
* Students and Graduates
* Policy Makers and Regulators
* Consultants and Advisors
* Technology Enthusiasts
* Suppliers and Manufacturers
* Startups and Innovators
* Researchers in Laser Education

**[View All Proceedings Here](https://icaleo.conferencespot.org/event-data)**

### **Program Tracks & Chairs**

To access the site please register [**here**](https://icaleo.org/attend). 

Please register for the ICALEO 2023 Conference to join the event.

ICALEO® brings together the brightest minds, seasoned professionals, and pioneering researchers from around the world. With a laser-focused agenda, ICALEO offers an exceptional platform to delve into the cutting-edge advancements, diverse applications, and transformative research that define lasers and electro-optics.

Today, welding of quartz glass is mainly carried out with gas torches and by hand. The use of gas torches means that a lot of energy gets lost in the actual process zone. In addition, the manual process can result in inhomogeneous weld seams. 
An automated laser process would make the quartz glass welding process more energy efficient and more repeatable. In this study, quartz glass plates up to 4.5 mm in thickness are welded together at an angle of 125° using filler materials. The purpose is to achieve a homogeneous weld (V-seam) with as few defects as possible using a lateral fiber or rod based deposition welding process. 
The main challenge is to get the melt to the contact point of the two glasses so that no air inclusions occur. A 400 µm fiber and a 1 mm rod are investigated as additional materials. The advantage of the fiber compared to the rod is that the lower area (contact point of the glasses) is easier to reach during the welding process. The disadvantage is that a very high fiber feed rate is required to fill the gap. This leads to a high consumption of filler material. Process parameters include the substrate to fiber feed ratio, laser power, spot diameter, and process gas pressure and angle. The samples are analyzed using an optical microscope and a laser confocal microscope.&nbsp;Preliminary studies have shown that comparable results can be achieved with both filler materials.

Using Fiber or Rod? - The Influence of Different Filler Materials During CO2 Laser Welding of Quartz Glass

Femtosecond lasers are now a key technology for high precision manufacturing. They offer high quality, small feature size, and can process virtually any material. However, due to the relatively small amount of ablated matter per pulse, they have so far been limited to small parts processing. The growing availability of high average power femtosecond lasers, now reaching the kiloWatt level, enables to bring the benefits of femtosecond laser micro-processing to the macro-scale. An attractive application is large area surface functionalisation. We report on new developments aimed at improving plane wings aerodynamics by femtosecond laser micro-texturing. The creation or riblets, which are grooves engraved in the direction of air flow, can lead to a reduction of up to 9% in fuel consumption and contaminants emission. Riblets have a small feature size: The pitch and height of the groove is typically on the order of a few tens of micrometers. Achieving the required precisionand processing speedover large surfaces is challenging. We report on a combination of high average power femtosecond laser and beam shaping, to enable beam splitting and square top-hat generation. We present texturing tests that demonstrate the feasibility of the propose technique. We show that changing the beam profile from circular gaussian to square top-hat significantly improves the process speed. The combination of high power laser and advanced beam shaping has the potential to enable the production of high quality surface structures for new aerospace applications.

Large Area Femtosecond Laser Surface Texturing for Improved Aerodynamic Performances

Laser surface texturing (LST) has been demonstrated to be an effective method to induce the icephobic characteristics on metallic surfaces, which can be exploited for several applications including aerospace, energy, and communication. Using femtosecond (fs) lasers, highly-repeatable multiscale surface topographies comprised of microscale patterns and self-organized micro/nanoscale features such as laser-induced periodic surface structures (LIPSS) can be fabricated. This study investigated the influence of multi-scale surface textures produced on aluminum plates by fs-LST on the anti-icing performance. Firstly, surface features with different morphologies were fabricated by varying the fs-LST process parameters such as hatch spacing, scanning speed and the number of scanning passes. Surface topography of the textures was characterized using optical profilometry and scanning electron microscopy whereas Energy Dispersive Spectroscopy was used for analyzing the chemical composition. The wettability of the surfaces was studied using static, advancing and receding contact angle measurements. Further, icephobicity evaluation was carried out using two main techniques: &nbsp;i) by measuring the freezing time delay using an optical goniometer equipped with a subzero Peltier cell and, ii) by measuring the ice adhesion strength using an ice adhesion set-up based on horizontal shear stress application. Icing analysis and ice adhesion tests indicated that optimal microscale patterns overlapped with LIPSS features effectively increase the freezing time, mostly through the existence of the Cassie-Baxter regime at the interface between ice and textured surface, with a beneficial reduction in the ice adhesion strength. These results highlight that surface texturing by fs lasers is effective in achieving icephobic surfaces.

Effect of Femtosecond Laser Textured Surface Morphology on the Icephobic Characteristics of Aluminium

GHz burst mode femtosecond (fs) laser processing that contains a series of fs laser pulse (intra-pulse) trains with a pulse interval of several hundred picoseconds, has been attracting considerable attention, since it can offer some distinct characteristics in material processing compared with the conventional fs laser irradiation scheme (single-pulse mode). Specifically, laser ablation with the GHz burst mode can be achieved higher-quality with enhanced ablation efficiency than that by the single-pulse mode. Most of the research using GHz burst mode to date has been focused on ablation of materials. The objective of this study is to examine the possibility of GHz burst mode fs laser processing for the fabrication of novel nanostructures, that is different from laser-induced periodic surface structures (LIPSS) by the conventional single-pulse mode. 
In the experiment, linearly-polarized fs laser pulses (central wavelength 1030 nm, pulse width 220 fs) were focused onto crystalline silicon and titanium surfaces. It’s well known that the single-pulse mode creates nanoripple structures on both substrates, whose direction is perpendicular to the laser polarization direction. &nbsp;Interestingly, we found that GHz burst mode fs laser pulses can form unique two-dimensional LIPSS on both substrates with periodic structures perpendicular and parallel to the laser polarization direction. The formation mechanism of 2D LIPSS is discussed and their surface properties are characterized.

Novel 2D Periodic Surface Structures Fabricated by Femtosecond Laser Pulses with GHz Burst Mode

Seurat Technologies has developed an optically-addressed light valve used for high repetition rate dynamic laser beam shaping for primary use in Metal Additive Manufacturing [1]. This patented Area Printing® process—analogous to a programmable stamp—delivers high-power laser pulses to a bed of metal powder that locally sinters and bonds to form fully dense metal parts across a wide range of industrial applications. 
Area Printing® enables physical and economic scaling for Additive Manufacturing, while maintaining high spatial resolution, capable of printing features beyond reach of conventional manufacturing; with greater efficiency and minimal spatter defects. 
In this presentation, we address the optoelectronic properties of the optically-addressed photoconducting insulator (semiconductor) and liquid crystals that control the dynamic beam shaping, in addition to the limitations and challenges met with the use of industrial power laser intensities. Specifically, we focus on the contrast ratio achieved between dark and bright fields, the resulting spatial resolution of the beam delivered to the print bed, and the temporal response of the processed beam, as it relates to the semiconductor photoexcited carrier dynamics and mid-bandgap states mediated relaxation pathways, and the related electrical properties of the beam shaping device. 
Parasitic absorption imposes further device-level constraints that we characterize temporally and spatially via multi-physics finite element analysis of the thermomechanical response when the device is exposed to kW or MW levels of laser power. Key focus is placed on semiconductor and thermal management challenging the performance capabilities in light valves used in high power Additive Manufacturing. 
[1]&nbsp; https://www.seurat.com/area-printing

Light Valve Technology for Rapid, High Resolution 3D Area Printing

Extreme High-Speed Directed Energy Deposition (EHLA) is a modified variant of the laser based Directed Energy Deposition (DED-LB) and is being applied as an efficient coating process for rotational symmetric components. Characteristic for EHLA processes are feed rates of up to 200 m/min which result in smaller weld bead deposition and thinner layer thicknesses compared to conventional DED-LB. When transferred to Additive Manufacturing (AM) this characteristic utilizes the potential of depositing thin-walled filigree structures at deposition rates which are comparable to typical DED-LB processes (EHLA3D). 
Due to the high feed rates typical EHLA handlings are lathe type machines which realize the relative movement by rotating the rotational symmetric component. During the recent years the transfer to AM processes were demonstrated on a tripod machine developed by ponticon GmbH in collaboration with Fraunhofer ILT. The results of this work were achieved with a modified CNC-type machine which is capable of feed rates of up to 30 m/min. 
In this work process parameters were developed for the deposition of thin-walled filigree structures with the Ni-based superalloy IN718. Single tracks with constant feed rates and variation of beam diameter and powder mass flow were deposited and analysed regarding the resulting weld bead dimension. Then process parameters were selected and transferred to the deposition of thin walls and guidelines of the parameter adaption towards thin-walled deposition were defined. Depending on the developed parameter sets wall thicknesses between 300 µm – 500 µm are achieved.

Process Development and Process Parameter Guidelines for Thin Wall Deposition with IN718 using Extreme High Speed Laser

Laser metal deposition (LMD) is a blown powder process used for the additive manufacturing of large as well as complex parts. The laser spot size is determined by the fiber optic cable and by the imaging ratio of the process optics. Spot sizes typically used for LMD can range between 200 µm up to several millimeters. Zoom optics are able to change the laser spot focus within seconds during the process. However industrial powder nozzles are still static in their powder spot size. Changing the powder spot size accordingly to the laser spot size could lead to a desirable union of time savings when printing large volumes while also generating fine near-net-shape features. 
To overcome the current limitations in the LMD process, this work examines an adaptive powder nozzle system. In this discrete coaxial layout of three single powder nozzles the individual powder nozzles can be adjusted closer and further from the process to dilate or shrink the powder focus. Different diameters of powder channels are examined. The resulting powder propagation behavior is characterized for different settings of the single powder nozzles. Single tracks are welded with different nozzle settings for a fine and coarse powder spot, while accordingly changing the laser spot size with a zoom optic. The laser power is closed-loop controlled by a 2-color pyrometer to achieve comparative process temperatures. The single tracks are evaluated with regard to their geometry. High-Speed imaging gives supplementary information on the welt track generation.

Adaptive Power Nozzle Setting for Enhanced Efficiency in Laser Metal Deposition

We report a series of in-situ monitoring experiments on the high-speed laser directed energy deposition (HSL-DED) with a discernible distance between the identified laser spot and melt pool boundary, termed melt pool lag, during the high-speed laser-substrate interaction. The experiments investigated the melt pool lag feature on both mild steel and 300M high-strength steel substrates at processing speeds from 5 to 20 m/min with and without powder delivery. The analysis of results indicates that the correlation between melt pool lag measurements and several deposit characteristics could shorten the parametric investigation cycle in HSL-DED. The melt pool lag measurement is positively proportional to the processing speed at a given incident laser power level. Further examinations also found that substrate material properties significantly impact melt pool lag for a given set of process conditions. The melt pool lag measurements obtained from the mild steel substrate was significantly higher than that on the 300M high-strength steel substrate. An analytical model on melt pool formation has been developed with temperature-dependent thermophysical data of substrate materials to estimate the melt pool lag in HSL-DED. The observation of melt pool lag feature and the proposed analytical model enhance the understanding of the melt pool dynamics in HSL-DED. They also provide insights to improve powder utilisation during HSL-DED deposition.

The Melt Pool Dynamics on Different Substrate Materials In High-Speed Laser Directed Energy Deposition Process

Automotive industry's shift towards low-emission electric vehicles and induce a huge demand for EV-batteries. Along the entire process chain of Li-battery production you will find a variety of potential new or already established laser applications which are crucial for the output of GW battery capacities. Within electrode manufacturing there is the already established laser cutting and notching with ns lasers but also new developments like laser-based drying processes by VCSEL or other diode emitters which are getting high attention. These technologies offer dedicated advantages in surface heating of coated electrode foils by IR-laser radiation resulting into a significant reduction of operating and energy costs and hence to a decrease of CO2 footprint. In cell assembly laser welding of demanding materials such as copper and aluminum are still essential for the entire battery system to secure technical functionality like electric conductivity, strength, and tightness. A common approach for internal connection of stacked foils combines both, a pre fixation of stacked foils by ultrasonic welding followed by laser welding to ensure highest electric conductivity. In addition, new laser-based production solution trends in cell assembly like e.g., media-tight welding of cover assembly in prismatic cell housing “Can-Cap” and busbar welding will be exemplified to meet highest quality and productiveness. 
Finally, in battery module and pack manufacturing laser and combined sheet metal manufacturing processes are key elements in smart factory solutions. Ground breaking new technologies like multi focus beam shapes open new horizons in e.g. gas tight welding of aluminum battery heat exchangers.

Laser Applications Trends in EV Battery Manufacturing

Laser beam welding is a very efficient process for joining copper pins in electric drives, which are referred to as hairpins. The occurrence of pores reduces the conducting cross-sectional area, which increases the electric resistance and further impairs the tensile strength of the joint. 
The present work compares different welding strategies regarding the formation of pores and spatters during welding cu-hairpins. The welding strategy was varied by different geometries of the scan contour, different beam shapes and an adaptive line energy. Different beam shapes were realized using a two-in-one beam delivery fiber and using a civan laser. In order to capture the formation of pores, the processing zone was observed by means of X-ray imaging at the IFSW in Stuttgart and at Petra III at Desy in Hamburg. The formation of spatters was observed using a high-speed camera. With the observation it was possible to separately determine the influence of scan contour and beam shape on the formation of pores and spatters. Finally, these findings were applied to identify beneficial welding strategies to reduce the formation of pores and spatters. Furthermore, tensile testing proves the increase of the tensile strength of the hairpins, which were welded with the optimized welding strategies.

Premium content

Downloads

Next from ICALEO 2023

Using Fiber or Rod? - The Influence of Different Filler Materials During CO2 Laser Welding of Quartz Glass

Similar lecture

A Parametric Study of the Laser Energy Absorption in High-power Laser Beam Welding