For most of the laser applications is optics equipped with antireflective coatings must. Therefore, laser damage resistance and stability at high energies of used components is a key performance limiting factor at the large portion of the user cases. In UV region, issue of laser damage is particularly enhanced as many optical materials tends to degrade at longer exposure and any contamination may accelerate that. In the following paper will be disseminated laser damage performance of selected commercially available optical windows equipped with AR coatings, designed for high-power lasers in UV region. Damage threshold measured with mm-size laser beam will be compared and influence of the long exposure to ultrashort pulses will be considered.
With numerous manufacturers providing different laser-induced damage threshold (LIDT) values in the nanosecond regime, a simple ranking based on numbers alone may not provide a clear picture of the best choice. Variations in testing procedures, albeit following the ISO 21254 standard, further complicate the selection process. By employing a comprehensive 1-on-1 test procedure, it becomes possible to observe various parameters that influence LIDT values. When sharing test results within the community, adhering to good practices and meticulous attention to the error budget and its contributors are crucial. Above all, laser optics users must comprehend the intricacies of laser-induced damage testing and seek detailed information instead of relying solely on numerical comparisons. This study explores the challenges and considerations in selecting and testing laser optics, emphasizing the importance of a comprehensive approach.
The removal of multi-compound protective thin PVD films for stressed industrial tools using laser ablation could enhance or replace currently used procedures. Developing a laser removal process can shorten the processing time and costs. In the first step, the laser-induced damage threshold of the thin CrAlSiN coating and the WC-Co material was measured. Nanosecond and picosecond laser pulses were used for comparison. Furthermore, the dependence of the ablated material volume and ablation depth on the fluence and the number of pulses was measured. Finally, spectral analysis of the laser plasma generated during ablation was performed.
Laser-Induced Deep Etching (LIDE) is considered as the one of the most promising techniques for production of so-called TGVs (Through Glass Vias). In the production process, thin glass sheet is treated with ultra-short lasers pulses to induce surface and volume modification, allowing efficient wet etching and formation of through hole. Precise knowledge of damage threshold of such glass is essential when optimizing the whole process and scaling up the production via laser beam parallelization. In following paper, we present recent results on LIDT measurement of D263 glass sheets at wavelengths 1030 nm and 515 nm, effective utilization of such knowledge for setting up multi-Bessel beam processing optics, and we demonstrate resulting substrates with TGVs.
Glass sheets with ~ 0.1 mm thickness are a promising material from which interposers for high density chip packaging can be produced due to its electrical and mechanical properties. For successful application in microelectronics, it is necessary to develop a way of efficient, high-speed production of interconnecting holes through such glass substrate, socalled through glass vias (TGVs). One of the most promising technique is Laser-Induced Deep Etching (LIDE), where picosecond laser is used to modified particular areas on the glass substrate. Then, using wet etching process, the area exposed to the laser will be etched more quickly than unexposed area. However, effective and large-scale glass modification often requires use of high-energy pulsed UV laser source, which unnecessary complicates the whole application. Here we present effective preparation of treated glass substrate using Yb:YAG laser at its fundamental wavelength 1030 nm, which is capable to overcome such disadvantage. We induced 5-15 m diameter regular affected areas on ~100 m substrate at various pitch, enabling scaled-up production of precise TGVs.
Metal Additive Manufacturing has been recognized as a technology of the future providing numerous benefits such as the production of complex shape and lightweight parts, easy customization, design freedom, etc. However, there are many areas where metal additive manufacturing cannot be applied since the quality of produced parts still does not satisfy the requirements of high-demanding industries for the production of their critical parts. Recently, Laser Shock Peening (LSP) has been investigated as a post-processing technique in metal additive manufacturing, primarily for the improvement of fatigue behavior. Here we will present improvements in fatigue life, the analysis of microstructure, and all the benefits LSP can bring to Metal Additive Manufacturing, for two types of material; stainless steel AISI 304L and titanium alloy Ti6Al4V.
Laser shock peening as one kind of surface technique is used to enhance the mechanical property of metals, like aluminum alloy, stainless steel, and titanium alloy. The Ti6Al4V alloy specimens are processed with laser shock peening technology by nanosecond laser with a square laser spot. The hardness near-surface region and residual stress distribution in the top layer of Ti6Al4V alloy specimen are measured by Vickers hardness tester and hole drilling tester. The results show that the shock wave formed by laser shock peening can induce compressive residual stress in the top layer of Ti6Al4V alloy, which is beneficial for the improvement of fatigue life of Ti6Al4V alloy when it is used in aviation. The hardness of the near-surface region increases slightly in this research.
So-called hybrid mirrors consists of broadband metallic surface coated with high reflection dielectric multilayer designed for specific wavelength. Such reflectors become more important with progressing development of multiband laser sources realized using parametric down conversion system, in particular for ultrashort-pulsed sources. Multiple pulse picosecond laser induced damage on such mirrors, tested by s-on-1 ISO-compliant method, is important part in development of such components, as there is a need in feedback predicating performance of novel designs. In following paper, we examine laser damage performance of several different designs of silver protected mirrors equipped with HR coating at 1030 nm.
Laser beam distribution system is a complex system allowing safe and precise delivery of laser beams. The new generation of HiLASE high energy diode-pumped solid state laser systems with high repetition rates requires advanced approach, which makes design of the distribution system a state-of-the-art challenge. The distribution system delivers four different laser beams multiway from laboratories to several experimental stations. We report results in design and testing of a distribution system for high-power laser beam delivery developed within the HiLASE project of the IOP in the Czech Republic. We use modular framing that allows gradual modification and flexible change of the distribution according to current laboratory needs. The system is extendable and has already proven performance.
Laser Induced Damage Threshold (LIDT) is an important property of laser system components. It is obtained as a statistical value from controlled experiments and defines the maximum optical intensity, which does not cause damage to certain components. Correlation between maximum optical intensity, beam pulse length and focal spot size provides a unique characterization of a specimen. Some specimen requires conditions or environment unreachable in stationary setup, therefore a lighten, portable, version of testing setup may be used with proper source and surroundings. The advantage of the mobile LIDT station is access to different laser systems with variety of beam properties (repetition rate, pulse length, etc). In following paper were investigated accuracy of measurements done by the mobile LIDT station and copared to stationary, ISO compliant LIDT station measurements as reference.
Optical glasses, in particular fused silica and BK7, are the most common and used substrates for components manufacturing in laser technology and optics in general. Dielectric coating technologies for those materials are well known and established; both high-reflective and anti-reflective coatings prepared on such substrates demonstrated laser induced damage threshold (LIDT) exceeding tens J·cm-2 in nanosecond regime. However, LIDT became a major issue in further exploitation of crystalline materials as yttrium aluminum garnet (YAG) crystals, which often serves as a host in laser media and would be used in other components as well. One of the current challenge is the ability to transfer thin film coating technology used on glass to YAG in order to reach the same performance as in the case of fused silica or BK7 counterparts. HR dielectric coatings prepared on fused silica, BK7 and YAG substrates by reactive or ion-assisted e-beam deposition technique were tested on LIDT by s-on-1 method according to the ISO standard recommendations. Results from tests are presented and discussed in following paper.
Around BIVOJ laser system, a new generation diode pump solid state laser (10-100J energy in 2-10 ns pulses with 10 Hz repetition frequency at 1030 nm) recently was developed a LSP experimental station. In this paper status and further developments of LSP facility at HiLASE Centre as well as further BIVOJ laser upgrades are presented. Residual stress curves representing preliminary results on treating Aluminum 7075 alloy will be also reported.
Recent development of a station dedicated to Laser Shock Peening around newly developed BIVOJ laser system is reported. We also describe further plans related to upgrade of the laser system itself as well as plans for establishment of a dedicated sample preparation and characterization lab.
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