This PDF file contains the front matter associated with SPIE Proceedings Volume 10097, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

We have been developing CO₂-Sn-LPP EUV light source which is the most promising solution as the 13.5nm high power light source for HVM EUVL since 2003. Unique original technologies such as; combination of pulsed CO₂ laser and Sn droplets, dual wavelength laser pulse shooting and mitigation with magnetic field have been developed in Gigaphoton Inc.. The theoretical and experimental data have clearly showed the advantage of our proposed strategy. We demonstrated 117W EUV power (I/F clean in burst), 50 kHz, 22 hours stable operation at Pilot #1 device. Target of this device is 250 W EUV power by 27 kW pulsed CO₂ driver laser system.

Femtosecond lasers are more and more used for material processing and lithography. Femtosecond laser help to generate three dimensional structures in photoresists without using masks in micro lithography. This technology is of growing importance for the field of backend lithography or advanced packaging. Optical glasses used for beam shaping and inspection tools need to withstand high laser pulse energies.

Femtosecond laser radiation in the near UV wavelength range generates solarization effects in optical glasses. In this paper results are shown of femtosecond laser solarization experiments on a broad range of optical glasses from SCHOTT. The measurements have been performed by the Laser Zentrum Hannover in Germany. The results and their impact are discussed in comparison to traditional HOK-4 and UVA-B solarization measurements of the same materials. The target is to provide material selection guidance to the optical designer of beam shaping lens systems.

TNO is developing a High Power Adaptive Mirror (HPAM) to be used in the CO₂ laser beam path of an Extreme Ultra- Violet (EUV) light source for next-generation lithography. In this paper we report on a developed methodology, and the necessary simulation tools, to assess the performance and associated sensitivities of this deformable mirror. Our analyses show that, given the current limited insight concerning the process window of EUV generation, the HPAM module should have an actuator pitch of ≤ 4 mm. Furthermore we have modelled the sensitivity of performance with respect to dimpling and actuator noise. For example, for a deformable mirror with an actuator pitch of 4 mm, and if the associated performance impact is to be limited to smaller than 5%, the actuator noise should be smaller than 45 nm (rms). Our tools assist in the detailed design process by assessing the performance impact of various design choices, including for example those that affect the shape and spectral content of the influence function.

We introduce a novel technique allowing simultaneous combining and reshaping of several non-coherent laser sources. This Multi-Plane Light Conversion technique is based on a passive, tailored and multi-reflective phase element which realizes intrinsically lossless unitary transforms. This approach is particularly suitable for multiple kilowatt laser beam shaping applied to improved material processing. We present numerical and experimental results of 3 applications of this shaper: a multiple multi-mode laser beam shaper, a beam shaper and combiner for generating adaptive tailored beam, and a beam combiner managing up to ten incoherent laser beams with optimum output beam quality (M²). High power handling, up to 12 kW, of MPLC based shaper is also demonstrated.

For many years, laser beam shaping has enabled users to achieve optimized process results as well as manage challenging applications. The latest advancements in industrial lasers and processing optics have taken this a step further as users are able to adapt the beam shape to meet specific application requirements in a very flexible way. TRUMPF has developed a wide range of experience in creating beam profiles at the work piece for optimized material processing. This technology is based on the physical model of wave optics and can be used with ultra short pulse lasers as well as multi-kW cw lasers. Basically, the beam shape can be adapted in all three dimensions in space, which allows maximum flexibility. Besides adaption of intensity profile, even multi-spot geometries can be produced. This approach is very cost efficient, because a standard laser source and (in the case of cw lasers) a standard fiber can be used without any special modifications. Based on this innovative beam shaping technology, TRUMPF has developed new and optimized processes. Two of the most recent application developments using these techniques are cutting glass and synthetic sapphire with ultra-short pulse lasers and enhanced brazing of hot dip zinc coated steel for automotive applications. Both developments lead to more efficient and flexible production processes, enabled by laser technology and open the door to new opportunities. They also indicate the potential of beam shaping techniques since they can be applied to both single-mode laser sources (TOP Cleave) and multi-mode laser sources (brazing).

The essential basis for a reliable and target-aimed process control is the understanding of the interaction between the laser beam and the treated material and this was gained by thorough research on the influence of the process input parameters on the interaction sub processes and on the treatment result. The main players con-ducting this research over the decades have been research facilities and institutes and this research is still in progress. Since the moment when it was possible to achieve the necessary power density to start the process of deep penetration welding, accompanied by a keyhole, there is hope - and need - to measure e.g. the depth of this vapor channel. In the decades in which the technology of deep penetration welding has been used, various approaches have been developed that allow a measurement of the depth of the keyhole. The aim of this contribution is to show a compact overview on the different approaches to monitor and/or control micro and macro laser welding processes and especially bring out those which successfully have been transferred from laboratory to serial production in the recent past and will be in the near future. Laser materials processing in general offers several possibilities for process monitoring systems or process control but the complexity of the process itself, meaning the dependence of the processing result on several process input parameters, does not facilitate their use. As only continuous supervision of the manufacturing process can guarantee the high demands on the quality of the produced parts, process monitoring systems have become more and more standardized devices in laser applications. There is no doubt that the basis for reliable on-line process monitoring systems is the possibility to measure significant indicators, which demonstrates the instantaneous condition of the interaction zone and/or neighboring areas. This contribution to the Photonics West 2017 LASE conference on the one hand will demonstrate an approach using chromatic coded line sensors for post-weld inspection, on the other hand will show a sensor, based on interferometric principle, which is capable to in-situ measure keyhole depth during deep penetration laser welding and further potential of this sensor approach.

In laser welding applications optical coherence tomography (OCT) is used to measure the capillary depth for process monitoring and process control. A controlled constant weld depth is expected to run applications closer to their process limits and reduce the number of destructive sample inspections. An essential premise is a reliable weld depth measurement independent from influencing factors. This work analyzes the influence of laser power, beam diameter, feed rate, and work piece material on the weld depth measured using the OCT technology. The results obtained by using fixed laser optics are compared to the corresponding results from scanner optics.

Laser welding is the state of the art joining technology regarding productivity and thermal loads and stress on the workpiece. In deep penetration laser welding the quality of the resultant welds strongly depends on the stability of the capillary. The highly dynamic depth fluctuations are of major influence on the controllability of the laser welding process and on the prevention of weld defects. In the present paper the capillary dynamics is investigated by means of time- and spatially resolved in-process X-ray imaging and optical coherence tomography. The X-ray diagnostics allows measuring the geometry of the capillary with frame rates of 1 kHz, while the optical coherence tomography enables the determination of the capillary depth with an acquisition rate of up to 70 kHz. These measurements are correlated to time varying input laser power to provide profound insight in the dynamics of the laser welding process. The measurements are performed for copper, aluminum and mild steel. The capillary depth resulting from arbitrary laser power modulation was investigated. Thereby, the response of the capillary depth to laser power changes was determined. Based on these measurements the changes of the capillary depth in deep penetration laser welding were described by methods known from control theory. These analyses can be utilized to optimize control strategies, to calibrate transient simulations of deep penetration laser welding and to identify the influence of material properties.

To ensure the competitiveness of manufacturing companies it is indispensable to optimize their manufacturing processes. Slight variations of process parameters and machine settings have only marginally effects on the product quality. Therefore, the largest possible editing window is required. Such parameters are, for example, the movement of the laser beam across the component for the laser keyhole welding. That`s why it is necessary to keep the formation of welding seams within specified limits. Therefore, the quality of laser welding processes is ensured, by using post-process methods, like ultrasonic inspection, or special in-process methods. These in-process systems only achieve a simple evaluation which shows whether the weld seam is acceptable or not. Furthermore, in-process systems use no feedback for changing the control variables such as speed of the laser or adjustment of laser power. In this paper the research group presents current results of the research field of Online Monitoring, Online Controlling and Model predictive controlling in laser welding processes to increase the product quality. To record the characteristics of the welding process, tested online methods are used during the process. Based on the measurement data, a state space model is ascertained, which includes all the control variables of the system. Depending on simulation tools the model predictive controller (MPC) is designed for the model and integrated into an NI-Real-Time-System.

This paper presents OpenLMD, a novel open-source solution for on-line multimodal monitoring of Laser Metal Deposition (LMD). The solution is also applicable to a wider range of laser-based applications that require on-line control (e.g. laser welding). OpenLMD is a middleware that enables the orchestration and virtualization of a LMD robot cell, using several open-source frameworks (e.g. ROS, OpenCV, PCL). The solution also allows reconfiguration by easy integration of multiple sensors and processing equipment. As a result, OpenLMD delivers significant advantages over existing monitoring and control approaches, such as improved scalability, and multimodal monitoring and data sharing capabilities.

Laser beam welding of materials like copper, lightweight aluminum alloys with high magnesium content as well as aluminum pressure die casting is still a challenge. Caused by facts like:  the high reflectivity,  low viscosity of the meld pool,  alloying elements with low evaporating temperature and  dissolved gases, spatter, pores and melt pool ejection can occur with reduced process stability and will lead to bad weld seam quality. On the other hand for potential joining applications in the field of electro mobility and lightweight design stable laser welding processes are required. The use of high power cw-laser source with brilliant beam quality and different wave length in combination with a high-frequent 2D beam oscillation is a promising approach to overcome these limitations. The influence of different wavelengths (515 nm and 1070 nm) for lasers with comparable beam parameter product and power up to 1000 W @ 515 nm and up to 5000 W @ 1070 nm were investigated. A keyhole modulation using a 2D high frequent beam oscillation up to 4 kHz was used for an improved weld process. As a result high quality welds with reduced porosity and less spatters occurred. The potential of this technology will be discussed for several materials and industrial applications for welding of aluminum pressure die casting of automotive components will be presented.

Solder joining is an all inorganic, adhesive free bonding technique for optical components and support structures of advanced optical systems. We established laser-based Solderjet Bumping for mounting and joining of elements with highest accuracies and stability. It has been proven for optical assemblies operating under harsh environmental conditions, high energetic or ionizing radiation, and for vacuum operation. Spaceborne instrumentation experiencing such conditions and can benefit from inorganic joining to avoid adhesives and optical cements. The metallization of components, necessary to provide solder wetting, mainly relies on well-adhering layer systems provided by physical vapor deposition (PVD). We present the investigation of electroless Ni(P)/Pd/Au plating as a cost-efficient alternative under bump metallization of complex or large components unsuitable for commercially available PVD. The electroless Ni(P)/Pd/Au plating is characterized with respect to layer adherence, solderability, and bond strength using SnAg3Cu0.5 lead-free solder alloy.

In continuous wave keyhole-mode laser welding of high strength steel alloys hot cracking can occur. The hot crack susceptibility depends on the mutual interaction of several factors like the welding parameters, the alloy composition and the weld fixturing. In this paper we focus on the influence of the welding parameters and investigate the dependency of the laser power, the welding speed and the laser wavelength on the crack formation. X-ray images are used to visualize the hot crack patterns, which exhibit a pronounced periodicity. To influence the hot crack formation, the incident energy input into the process was adapted. For specific welding parameters, we show exemplarily the prevention of hot cracking by the use of a twin-spot optics.

Research and development carried out by the ISF Welding and Joining Institute of RWTH Aachen University has proven that combining high power laser and low vacuum atmosphere provides a welding performance and quality, which is comparable to electron beam welding. The developed welding machines are still using a beam forming which takes place outside the vacuum and the focusing laser beam has to be introduced to the vacuum via a suitable window. This inflexible design spoils much of the flexibility of modern laser welding. With the target to bring a compact, lightweight flying optics with flexible laser transport fibers into vacuum chambers, a high power fiber-fiber coupler has been adapted by II-VI HIGHYAG that includes a reliable vacuum interface. The vacuum-fiber-fiber coupler (V-FFC) is tested with up to 16 kW sustained laser power and the design is flexible in terms of a wide variety of laser fiber plug systems and vacuum flanges. All that is needed to implement the V-FFC towards an existing or planned vacuum chamber is an aperture of at least 100 mm (4 inch) diameter with any type of vacuum or pressure flange. The V-FFC has a state-of-the-art safety interface which allows for fast fiber breakage detection for both fibers (as supported by fibers) by electric wire breakage and short circuit detection. Moreover, the System also provides connectors for cooling and electric signals for the laser beam optics inside the vacuum. The V-FFC has all necessary adjustment options for coupling the laser radiation to the receiving fiber.

As one can easily ascertain by simple estimates, a nanosecond-scale laser pulse can overheat the thin surface layer of a light-absorbing material to a temperature of thousands Kelvins. Thermal emission of this laser-heated surface (laserinduced incandescence, LII) is easily observed in the visible spectral range by a photomultiplier. The local LII intensity of the laser-heated surface depends on the presence of undersurface structural. In the present work, we perform computer simulations of the processes of transient laser heating of a surface layer with hidden submicron-sized voids located under the surface in order to assess the possibilities of their visualization via LII. Calculations showed that undersurface microscopic inhomogeneities can significantly affect the local LII intensities of the laser-irradiated surface. The calculations were performed with the ordinary heat diffusion equation, assuming temperature-independence of material parameters as a first approximation. The intensity of LII was calculated with the using of Planck’s blackbody emission law at a fixed wavelength of 500 nm.

Porous graphite plates, cylinders and cones with densities of 1.55-1.82 g/cm³ were irradiated by a 10 kW fiber laser at 0.075 –3.525 kW/cm² for 120 s to study mass removal and crater formation. Surface temperatures reached steady state values as high as 3767 K. The total decrease in sample mass ranged from 0.06 to 6.29 g, with crater volumes of 0.52 - 838 mm³, and penetration times for 12.7 mm thick plates as short as 38 s. Minor contaminants in the graphite samples produced calcium and iron oxide to be re-deposited on the graphite surface. Significantly increased porosity of the sample is observed even outside of the laser-irradiated region. Total mass removed increases with deposited laser energy at a rate of 4.83 g/MJ for medium extruded graphite with an apparent threshold of 0.15 MJ. Visible emission spectroscopy reveals C2 Swan and CN red, CN violet bands and Li, Na, and K ²P_3/2,1/2 – ²S_1/2 doublets. The reacting boundary layer is observed using a mid-wave imaging Fourier transform spectrometer (IFTS) at 2 cm^-1 spectral resolution, 0.5 mm/pixel spatial resolution, and 0.75 Hz data cube rate. A two-layer radiative transfer model was used to determine plume temperature, CO, and CO₂ concentrations from spectral signatures. The new understanding of graphite combustion and sublimation during laser irradiation is vital to the more complex behavior of carbon composites.

Short and ultra-short lasers are widely used for subtractive processes in modern advanced nano to microelectronics industry. i.e in manufacturing of data display units, interactive (touch) sensors, bio/ physical sensors– while at the same time connect to the internet things through a micro– millimetre–sized antennae. The integration of different components are only possible by precise and controlled processing. Laser subtractive processes require nanometre depth precision, micron lateral precision, minimal side wall thermal damage, minimal surface kerfs, no substrate damage and no contamination by nanoparticles. In this study, we optimize such processes by real time observations that detect layer removal and ablation mechanisms by optical emission based laser induced breakdown spectroscopy (LIBS). LIBS is a multi-elemental analytical technique, in which atomic and ionic characteristic emission lines are used to identify chemical composition of the target. This state of the art real time monitoring technique collect signals which originate from within the laser process interaction zone. Ultrashort laser pulses are used for the selective ablation of very thin layers, with precise stops at layer interfaces and minimal side-wall surface diffusion. This optical emission based technique is employed for real time monitoring in patterning, selective ablation and structuring of industrial materials like ITO, monolayer graphene and molybdenum, aluminum and molybdenum (MAM) based hetero-structures. Spatial resolution in the order of nm is achieved and experimental parameters (of laser, spectrometer and optics) are evaluated to optimize and apply it in industrial processing.

The recent 1μm-laser cutting market is dominated by fiber and disk lasers due to their excellent beam quality of below 4mm*mrad. Teradiode’s 4kW direct diode laser source achieves similar beam quality while having a different beam shape and shorter wavelengths which are known for higher absorption rates at the inclined front of the cutting keyhole. Research projects, such as the HALO Project, have additionally shown that polarized radiation and beams with shapes different from the typical LG00 lead to improved cut quality for ferrous and non-ferrous metals. [1] Diode laser have the inherent property of not being sensitive to back reflection which brings advantages in cutting high-reflective materials. The II-VI HIGHYAG laser cutting head BIMO-FSC offers the unique feature of machine controlled and continuous adjustment of both the focus diameter and the focus position. This feature is proven to be beneficial for cutting and piercing with high speed and small hole diameters. In addition, the optics are designed for lowest focus shift.

As a leading laser processing head manufacturer, II-VI HIGHYAG qualified its BIMO-FSC MZ (M=magnification, Z=focus position) cutting head for Teradiode’s 4kW direct diode laser source to offer a cutting-edge solution for highpower laser cutting. Combining the magnification ability of the cutting head with this laser source, customers experience strong advantages in cutting metals in broad thickness ranges. Thicknesses up to 25mm mild steel can easily be cut with excellent edge quality.

Furthermore, a new optical setup equivalent to an axicon with a variable axicon angle is demonstrated which generates variable sized ring spots. The setup provides new degrees of freedom to tailor the energy distribution for even higher productivity and quality.

The High-Power Focus Mirror we present in this paper gives access to dynamic focus position adaptation along 3.6 mm in high-power laser manufacturing. We developed and tested a new thermo-mechanical design for a unimorph deformable mirror that provides an extensive focal length range down to -2 m focal length. Moreover, the mirror’s unique thermal characteristics enable high-power applications up to 6.4 kW (2000 W/cm²) with stable optical beam quality as thermal lensing is successfully suppressed. Thus, the laser’s optical beam quality M² is stable over the entire actuation and thermal range.

We will describe the design and the characterization of the High-Power Focus Mirror. The mirror setup is based on a unimorph concept using a piezoelectric actuator and a thin glass substrate with a highly reflective multilayer coating. An integrated copper layer improves the heat dissipation. Providing maximum stroke, as well as excellent dynamic properties, the deformable mirror substrate is mounted by our established compliant cylinders [1].

Furthermore, we investigate the incorporation of the High-Power Focus Mirror into a commercial laser-cutting system. We set up a laser-cutting test bench including a multimode laser source, the focus mirror, a commercial laser processing head, and measuring instruments. In this assembly, we measure the achievable focus position range as well as the laser beam quality.

With this focus mirror, we want to encourage new, innovative high-power application fields in 3D laser processing such as laser cutting, welding, and structuring.

Flexible beam delivery of high power pico- and femtosecond pulses offers great advantages in industrial applications. Complex free space beam delivery as found in robot or gantry systems can be replaced, laser safety and uptime increased and system integration in production environment simplified. Only recently fiber beam delivery has become available for ultrafast lasers while it has been an established standard for cw and pulsed laser sources for many years. Using special kinds of fiber that guide the laser beam mostly inside a hollow core, nonlinear effects and catastrophic damage that would arise in conventional glass fibers can be avoided. Today, ultrafast pulses with several 100 μJ and hundreds of MW can be transmitted in quasi single mode fashion with micro-structured hollow core fibers. During the last years we have developed a modular beam delivery system that suits industrial ultrafast lasers and can be integrated into existing processing machines. Micro-structured hollow core fibers inside the sealed laser light cable efficiently guide high-power laser pulses over distances of several meters with excellent beam quality, while power, pulse duration and polarization are maintained. We report on the technology required for fiber beam delivery of ultrafast laser pulses and discuss requirements for successful integration into industrial production as well as achievable performance under realistic operation and show examples of micromachining applications.

Standardized production systems which can be implemented, programmed, maintained and sourced in a simple and efficient way are key for a successful global production of automobiles or related parts at component suppliers. This is also valid for systems, which are built by laser based processes. One of the key applications is remote laser welding (RLW) of “Body in White” (BIW) parts (such as hang-on parts, B-Pillars, side frames, etc.), but also builtin components (such as car seats, batteries, etc.). The majority of RLW applications are based on the implementation of a 3-D scanner optic (e.g. the PFO 3D from TRUMPF) which positions the laser beam on the various component surfaces to be welded. Over the past 10 years it has been proven that the most efficient way to build up the RLW process is to have a system where an industrial robot and a scanner optic are combined in one production cell. They usually cooperate within an “On-The-Fly” (OTF) process as this ensures minimum cycle times. Until now there are several technologies on the market which can coordinate both the robot and scanner in the OTF mode. But none of them meet all requirements of global standardized production solutions. With the introduction of the I-PFO (Intelligent Programmable Focusing Optics) technology the situation has changed. It is now possible to program or adopt complex remote processes in a fast and easy way by the “Teach-in” function via the robot teach pendant. Additionally a 3D offline designer software is an option for this system. It automatically creates the ideal remote process based on the part, fixture, production cell and required process parameters. The I-PFO technology doesn’t need additional hardware due to the fact that it runs on the controller within the PFO 3D. Furthermore it works together with different types of industrial robots (e.g. ABB, Fanuc and KUKA) which allow highest flexibility for the production planning phase. Finally a single TRUMPF laser source can supply up to six I-PFOs. This guarantees maximum beam-on time at the production line. Within this report the concept of the I-PFO technology (with mentioned functions) is described and is compared to the other existing ways for Remote Laser processing.

We report the first direct diode laser module integrated with a trepanning optic for remote oscillation welding. The trepanning optic is assembled with a collimated DirectProcess 900 laser engine. This modular laser is based on single emitters and beam combiners to achieve fiber coupled modules with a beam parameter product or BPP < 8 mm mrad at all power levels up to 1 kW, as well as free space collimated outputs with even lower BPP. The initial design consists in vertically stacking several diodes in the fast axis which leads to a rectangular output of about 100 W with BPP of <3.5 mm*mrad in the fast axis and <5 mm*mrad in the slow axis. Next, further power scaling is accomplished by polarization combining and wavelength multiplexing yielding high optical efficiencies of more than 80% and resulting in a building block module with over 500 W launched into a 100 μm fiber with 0.15 NA. The beam profile of the free space module remains rectangular, with a nearly flat top and conserves the beam parameter product of the original vertical stack without the power loss of fiber coupling. The 500 W building blocks feature a highly flexible emitting wavelength bandwidth. New wavelengths can be configured by simply exchanging parts and without modifying the production process. This design principle provides the option to adapt the wavelength configuration to match a broad set of applications, from the UV to the visible and to the far IR depending on the commercial availability of laser diodes. This opens numerous additional applications like laser pumping, scientific and medical applications, as well as materials processing applications such as cutting and welding of copper aluminum or steel. Furthermore, the module’s short lead lengths enable very short pulses. Integrated with electronics, the module’s pulse width can be adjusted from micro-seconds to cw mode operation by simple software commands. An optical setup can be directly attached instead of a fiber to the laser module thanks to its modular design. This paper’s experimental results are based on a trepanning optic attached to the laser module. Alltogether the setup approximately fits in a shoe box and weighs less than 20 kg which allows for direct mounting onto a 3D-gantry system. The oscillating weld performance of the 500 W direct diode laser utilizing a novel trepanning optic is discussed for its application to aluminum/aluminum and aluminum/copper joints.

In today’s industrial mass production, lasers have become an established tool for a variety of processes. As with any other tool, mechanical or otherwise, the laser and its ancillary components are prone to wear and ageing. Monitoring of these ageing processes at full operating power of an industrial laser is challenging for a range of reasons. Not only the damage threshold of the measurement device itself, but also cycle time constraints in industrial processing are just two of these challenges.

Power measurement, focus spot size or full beam caustic measurements are being implemented in industrial laser systems. The scope of the measurement and the amount of data collected is limited by the above mentioned cycle time, which in some cases can only be a few seconds.

For successful integration of these measurement systems into automated production lines, the devices must be equipped with standardized communication interfaces, enabling a feedback loop from the measurement device to the laser processing systems. If necessary these measurements can be performed before each cycle.

Power is determined with either static or dynamic calorimetry while camera and scanning systems are used for beam profile analysis. Power levels can be measured from 25W up to 20 kW, with focus spot sizes between 10μm and several millimeters. We will show, backed by relevant statistical data, that defects or contamination of the laser beam path can be detected with applied measurement systems, enabling a quality control chain to prevent process defects.

Surface pre-treatment is fundamental in thermal spraying processes to obtain a sufficient bonding strength between substrate and coating. Different pre-treatments can be used, mostly grit-blasting for current industrial applications. This study is focused on Cu-Al₂O₃ coatings obtained by Low Pressure Cold Spray on AW5083 aluminum alloy substrate. Bonding strength is measured by tensile adhesion test, while deposition efficiency is measured. Substrates are textured by laser, using a pattern of equally spaced grooves with almost constant diameter and variations of depth. Results show that bonding strength is improved up to +81% compared to non-treated substrate, while deposition efficiency remains constant. The study of the samples after rupture reveals a modification of the failure mode, from mixed failure to cohesive failure. A modification of crack propagation is also noticed, the shape of laser textured grooves induces a deviation of cracks inside the coating instead of following the interface between the layers.

Due to their outstanding mechanical properties, in particular their high specific strength parallel to the carbon fibers, carbon fiber reinforced plastics (CFRP) have a high potential regarding resource-efficient lightweight construction. Consequently, these composite materials are increasingly finding application in important industrial branches such as aircraft, automotive and wind energy industry. However, the processing of these materials is highly demanding. On the one hand, mechanical processing methods such as milling or drilling are sometimes rather slow, and they are connected with notable tool wear. On the other hand, thermal processing methods are critical as the two components matrix and reinforcement have widely differing thermophysical properties, possibly leading to damages of the composite structure in terms of pores or delamination. An emerging innovative method for processing of CFRP materials is the laser technology. As principally thermal method, laser processing is connected with the release of potentially hazardous, gaseous and particulate substances. Detailed knowledge of these process emissions is the basis to ensure the protection of man and the environment, according to the existing legal regulations. This knowledge will help to realize adequate protective measures and thus strengthen the development of CFRP laser processing. In this work, selected measurement methods and results of the analysis of the exhaust air and the air at the workplace during different laser processes with CFRP materials are presented. The investigations have been performed in the course of different cooperative projects, funded by the German Federal Ministry of Education and Research (BMBF) in the course of the funding initiative “Photonic Processes and Tools for Resource-Efficient Lightweight Structures”.

Metal corrosion is the main problem of all metal constructions and buildings. Annual losses resulting from corrosion in industrialized countries are estimated in the range from 2% to 4 % of gross national product. We used a CW fiber laser with the wavelength of 1064 nm and a power up to 18,4 W for laser irradiation of metal surfaces. We report on the optimal treatment of the metal corrosion with laser power density in the range of 93,3÷ 95,5 W/cm². After the process of laser treatment of steel surface we observe decreased roughness of steel and a small change in its chemical composition. There was an active research of new ways to improve the surface properties of metals and to increase the corrosion resistance. One of the breakthrough methods to protect the material against corrosion is laser treatment. We used a CW fiber laser operating at 1064 nm with up to 18,4 W output power. Experimentally, the samples (steel plates) were irradiated by laser for 35 seconds. Surface treatment of metal was provided at a room temperature and a relative air humidity of 55%. The impact of laser radiation on the surface has contributed to a small change of its chemical composition. It forms protective fluoride coating on the metal surface. The laser radiation significantly increased the concentration of fluorine in the metal from 0.01 atom. % to 5.24 atom. %. The surface roughness of steel has changed from 3.66 μ to 2.66 μ. Protective coatings with best resistance to corrosion were obtained with laser power density in a range of 93.3 W/cm² to 95.5 W/cm².

Recently infrared laser has faced resolution limit of finer micromachining requirement on especially semiconductor packaging like Fan-Out Wafer Level Package (FO-WLP) and Through Glass Via hole (TGV) which are hard to process with less defect. In this study, we investigated ablation rate with deep ultra violet excimer laser to explore its possibilities of micromachining on organic and glass interposers. These results were observed with a laser microscopy and Scanning Electron Microscope (SEM). As the ablation rates of both materials were quite affordable value, excimer laser is expected to be put in practical use for mass production.