Laser Station Research Articles

Enhancement of ceramic tool behaviour with textured grooves during machining of Inconel® 718

Inconel® 718, known for its excellent mechanical properties in extreme conditions, presents machining challenges due to its low machinability. The chip formation process, influenced by its high ductility and low thermal conductivity, leads to material adhesion and high cutting forces. Ceramic tools have been proposed to mitigate these inconveniences. Textured cutting tools have emerged as a promising solution, aiming to optimise tool-chip contact and, with it, the tribological conditions and the cutting forces. This study investigates the influence of textured grooves on ceramic tools when turning Inconel® 718. Two groove inclinations, 0° and − 25° relative to the cutting edge, were tested. Texturing was performed using a laser station. Experimental results showed improved tool wear characteristics with textured tools, indicating favourable chip extraction and reduced material adhesion. Cutting forces were notably lower with textured tools compared to the reference tool, attributed to reduced notch wear and altered chip flow. Chip morphology analysis revealed differences in chip shape and thermal stability between the reference and textured tools. In conclusion, textured tools, particularly those with − 25° inclined grooves, demonstrated enhanced performance in machining Inconel® 718.

Laser Observations of GALILEO Satellites at the CBK PAN Astrogeodynamic Observatory in Borowiec

The laser station (BORL) owned by the Space Research Centre of the Polish Academy of Sciences and situated at the Astrogeodynamic Observatory in Borowiec near Poznań regularly observes more than 100 different objects in low Earth orbit (LEO) and medium Earth orbit (MEO). The BORL sensor’s laser observation range is from 400 km to 24,500 km. The laser measurements taken by the BORL sensor are utilized to create various products, including the geocentric positions and movements of ground stations, satellite orbits, the components of the Earth’s gravitational field and their changes over time, Earth’s orientation parameters (EOPs), and the validation of the precise Galileo orbits derived using microwave measurements, among others. These products are essential for supporting local and global geodetic and geophysics research related to time. They are crucial for the International Terrestrial Reference Frame (ITRF), which is managed by the International Earth Rotation and Reference Systems Service (IERS). In 2023, the BORL laser station expanded its list of tracked objects to include all satellites of the European satellite navigation system GALILEO, totaling 28 satellites. During that year, the BORL laser station recorded 77 successful passes of GALILEO satellites, covering a total of 21 objects. The measurements taken allowed for the registration of 7419 returns, resulting in 342 normal points. The average RMS for all successful GALILEO observations in 2023 was 13.5 mm.

Satellite laser ranging to BeiDou-3 satellites: initial performance and contribution to orbit model improvement

In January 2023, the International Laser Ranging Service (ILRS) approved the tracking of 20 additional BeiDou-3 Medium Earth Orbit (BDS-3 MEO) satellites, integrating them into the ILRS tracking network. Before that, only 4 BDS-3 MEO satellites had been tracked. BDS satellites employ highly advanced GNSS components and technological solutions; however, microwave-based orbits still contain systematic errors. Satellite Laser Ranging (SLR) tracking is thus crucial for better identification and understanding of orbit modeling issues. Orbit improvements are necessary to consider BDS in future realizations of terrestrial reference frames, supporting the determination of global geodetic parameters and utilizing them for the co-location of GNSS and SLR in space. In this study, we summarize the first 6 months of SLR tracking 24 BDS-3 MEO satellites. The study indicates that the ILRS network effectively executed the request to track the entire BDS-3 MEO constellation. The number of observations is approximately 1300 and 450 for high- and low-priority BDS-3 satellites, respectively, over the 6 months. More than half of the SLR observations to BDS-3 MEO satellites were provided by 5 out of the 24 laser stations, which actively measured GNSS targets. For 14 out of 24 BDS-3 MEO satellites, the standard deviation of SLR residuals is at the level of 19–20 mm, which is comparable with the quality of the state-of-the-art Galileo orbit solutions. However, the SLR validation of the individual satellites revealed that the BDS-3 MEO constellation consists of more ambiguous groups of satellites than originally reported in the official metadata files distributed by the BDS operators. For 8 BDS-3 satellites, the quality of the orbits is noticeably inferior with a standard deviation of SLR residuals above 100 mm. Therefore, improving orbit modeling for BDS-3 MEO satellites remains an urgent challenge for the GNSS community.

Prototype System for Unmanned Reference Point Determination at the Sub‐Millimeter Level

AbstractThe determination of reference points for telescopes is crucial for obtaining the local‐tie vector for a multi‐technology co‐located station. Traditional methods suffer from labor‐intensive fieldwork, long execution cycles, and systematic errors due to the incident angle of the total station's laser beam on the prism. In this paper, we propose an algorithm aligning the prism pointing vector with the prism‐to‐total station vector and introduce a pan‐tilt platform and the Tianma VGOS telescope for sub‐millimeter unmanned reference point monitoring. Our results show that the prototype system based on the pan‐tilt achieves a formal error of ±100 μm (1σ) in reference point positions with just 2.5 hr of automated monitoring. The consistency of reference point positions is comparable to the local control network accuracy. Single‐direction observations may introduce a deviation of ±1 mm in the reference point compared to multiple direction observations. Preliminary experiments on the Tianma VGOS telescope have also shown that this system can efficiently automate the monitoring of prism scatter points (one measurement every minute) and achieve sub‐millimeter horizontal precision in reference point positions within a single day.

ANALYSIS OF THE INFLUENCE OF THE OBJECT’S ELEVATION ON LASER MEASUREMENTS OBTAINED IN BOROWIEC IN 2016–2023

This paper presents an analysis of how an object’s position above the horizon affects laser measurements obtained in laser station in Borowiec. The objects used for this analysis were active satellites from LEO (Low Earth Orbit) and MEO (Medium Earth Orbit) regimes, as well as space debris from LEO regime. The data used for this analysis spanned from the second half of 2016 to the first half of 2023. The results of tests performed at the BORL station indicate that for LEO objects, it is least effective to make observations when the object is close to the zenith, i.e. 80–90 degrees above the horizon. The highest returns are obtained when the object is at an elevation of 20–39 degrees. These results apply to both active satellites and space debris objects from the LEO regime. In the case of MEO satellites the highest returns are received when the object is at an elevation of 50–79 degrees.

The use of quality management tools to ensure safe working conditions at CO2 laser workstations

Abstract Dynamic development of various technologies replacing existing, difficult or in various ways arduous, is the reason for replacing equipment with modern ones. New equipment may be associated with a different power supply, a different way that the construction materials are processed or the tools used, than the previous one. Then arises a need to re-examine whether the working conditions at a workplace are safe, what onerous and hazardous factors are associated with the work. An example of such a technological change could be a laser processing, when equipment using a concentrated energy stream, properly controlled, produces a specific effect on materials. However, along with the benefits of the new technology, come also many risks, such as the effects of radiation on matter and the human body, electricity, fire hazards, the problem of toxic emissions and others. This paper presents the problem of ensuring work safety at a newly commissioned CO2 laser station. Technique of brainstorming was used to identify and analyze the working conditions and types of hazards. These may be different from what was previously known, partially known, or even unconscious. Ishikawa diagram was developed and shown to be an effective tool for detailing and structuring problems in relation to safety. In the case of a technical problem, a poka-yoke solution to eliminate the hazard was proposed. Problems occurring at the workstation during machining and related to its operation were assigned, using the affinity diagram, to specific departments of the company, according to its work organization, which can significantly facilitate the management of the work and employees of the different departments in the future, in order to ensure safe and hygienic working conditions.

Development of SMA Spring Linear Actuator for an Autonomous Lock and Release Mechanism: Application for the Gravity-Assisted Pointing System in Moon to Earth Alignment of Directional Devices

The next generation lunar reflector (NGLR) experiment is one of the experiments selected by NASA in the framework of the commercial lunar payload services (CLPS) initiative. The experiment, inspired by the lunar laser ranging (LLR) experiments of the Apollo era, is basically a single cube corner reflector (CCR) capable of reflecting a beam coming from a laser station on Earth that must be deployed on the Moon and pointed toward the mean Earth direction. In this work, a prototype of an actuator for the lock and release system of the reflector package was conceived, built, and tested in laboratory conditions. Since the entire pointing system must be passive, the actuator is designed to be operated by an SMA spring actuated by the thermal radiation of the Sun and regolith on the Moon. In lab conditions, the prototype, activated by a heat gun, showed the capability of the SMA spring to operate a lock and release pin, whose diameter is 4 mm, subjected to a preload of F = 7 N exerted by the releasing spring.

Multirod approach to enhance solar-to-laser conversion efficiency in the Odeillo solar furnace

A multirod solar laser station for the megawatt solar furnace (MWSF) in Odeillo, France, was conceptualized and numerically studied to improve the solar-to-laser power conversion efficiency. 18 heliostats from the 63-heliostat field were selected, and 347 kW of solar power was obtained at its focus. From there, a two-dimensional compound parabolic concentrator further concentrated and redistributed the solar rays toward 11 core-doped Nd:YAG rods, each fixed inside a fused silica flow tube. 11.40 kW of total multimode laser power was calculated, corresponding to a 3.29% solar-to-laser power conversion efficiency. This efficiency value represents an enhancement of 1.70 and 1.26 times over that attained from single-rod solar laser systems in side-pumping configuration tested in Odeillo, France, in which Nd:YAG rods were codoped with Cr3 + and Ce3 + ions, respectively. It was also 1.44 times higher than that obtained by a previously proposed side-pumping scheme with a solar flux homogenizer and 12 Nd:YAG rods for the same MWSF.

Experimental Research of the Structure Condition Using Geodetic Methods and Crackmeter

The article presents an approach to monitoring the structure’s condition with two measurement methods: the SHM-X crackmeter and the classic geodetic method of determining displacements, supplemented with additional information on the condition of the external environment obtained from thermal images. The study aimed to propose an approach combining geodetic and non-geodetic methods of assessing the condition of a structure and its effectiveness in practical application. The research facility is a public utility building of the Bydgoszcz University of Technology with a reinforced concrete structure. Objects of this type require periodic tests of their constancy. Interpreting the test results and identifying possible dangerous states that may indicate the risk of a construction failure is extremely important. The results presented in the article are an extension of the previous ones, in which several factors that could have a destructive effect on the structure were excluded. Observation of the object showed that only the reinforced construction plate is deformed. The only factor influencing the change in structure geometry is thermal changes. As part of the tests in places where cracks were noticed, the SHM-X crackmeter was used to measure the cracks’ opening. In the geodetic research, measurements of the measurement and control network displacement were carried out, in which the TDRA6000 laser station measurement technology was used. The control points were also placed in places where the width of the cracks was directly observed. The proposed approach, with the applied calculation scheme and supplementing the information with the temperature measurement with thermal images, showed the submillimeter accuracy of the determined 3D displacements of the controlled points. Additionally, the parallel application of these methods gives a complete picture of changes in the structure elements, in which signs of destruction appear under the influence of stress.

Measurements to Space Debris in 2016–2020 by Laser Sensor at Borowiec Poland

Abstract In 2014, a significant upgrade was made to the Borowiec (BORL 7811) laser-ranging system, which is the part of Space Research Centre of the Polish Academy of Sciences (SRC PAS). Two high-energy lasers modules were installed. First is the EKSPLA PL-2250, used for tracking objects equipped with retroreflectors. Second is the Continuum Surelite III, dedicated to the tracking of space debris without retroreflectors. In 2016, the BORL station joined the space debris tracking laser group and, since then, is tracking systematically inactive/defunct satellites and typical rocket bodies from LEO regime. Today, the BORL is tracking regularly about 80 different space debris objects. The paper presents the activity of the BORL laser station in observations of space debris. The results presented are from years 2016 to 2020. The sum of all passes from this period is almost 2 000, giving over 23 000 normal points. Average root mean square error (RMS) of objects with satellite laser ranging-dedicated (SLR-dedicated) retroreflectors ranges 1.5 cm–14 cm and of objects without SLR-dedicated retroreflectors ranges 8 cm–222 cm.

Sensitivity of HfO2-based RRAM Cells to Laser Irradiation

Today, the technology of resistive random access memory is used as a non-volatile memory. In this paper we investigate in details the sensitivity of the TiN/Ti/Al:HfO2/TiN-based 1T-1R resistive random access memory cells implemented in a 250 nm CMOS IHP technology to the laser irradiation. Experimental results show that the laser irradiation can influence the resistive state of RRAM cells significantly, i.e. precisely localized optical faults can be successfully injected. We focus on the selection of the configurable parameters of the laser station and their influence on the success of optical Fault Injections. Additionally, we localize sensitive areas of attacked chips. Based on the determined sensitive areas we show that metal fillers atop memory cells influence on success of optical fault injection attacks.

LARAMOTIONS: a conceptual study on laser networks for near-term collision avoidance for space debris in the low Earth orbit

A conceptual study has been carried out on laser station networks to enhance Space Situational Awareness and contribute to collision avoidance in the low Earth orbit by high-precision laser tracking of debris objects and momentum transfer via photon pressure from ground-based high-power lasers. Depending on the network size, geographical distribution of stations, orbit parameters, and remaining time to conjunction, multipass irradiation enhances the efficiency of photon momentum coupling by 1-2 orders of magnitude and has the potential to eventually yield a promisingly significant reduction of the collision rate in low Earth orbit.

Zigzag Multirod Laser Beam Merging Approach for Brighter TEM00-Mode Solar Laser Emission from a Megawatt Solar Furnace

An alternative multirod solar laser end-side-pumping concept, based on the megawatt solar furnace in France, is proposed to significantly improve the TEM00-mode solar laser output power level and its beam brightness through a novel zigzag beam merging technique. A solar flux homogenizer was used to deliver nearly the same pump power to multiple core-doped Nd:YAG laser rods within a water-cooled pump cavity through a fused silica window. Compared to the previous multibeam solar laser station concepts for the same solar furnace, the present approach can allow the production of high-power TEM00-mode solar laser beams with high beam brightness. An average of 1.06 W TEM00-mode laser power was numerically extracted from each of 1657 rods, resulting in a total of 1.8 kW. More importantly, by mounting 399 rods at a 30° angle of inclination and employing the beam merging technique, a maximum of 5.2 kW total TEM00-mode laser power was numerically extracted from 37 laser beams, averaging 141 W from each merged beam. The highest solar laser beam brightness figure of merit achieved was 148 W, corresponding to an improvement of 23 times in relation to the previous experimental record.

An accurate and robust metrological network for coherent optical frequency dissemination

We introduce multi-branch repeater laser stations (MLSs) for the dissemination of an ultra-stable signal from one point to multiple users and the simultaneous evaluation of the stability and accuracy of multiple links. We perform the study of the noise floor of this new instrument. We present then an optical fiber network of 4800 km built with three MLSs and 13 repeater laser stations (RLSs). We show the multi-user optical frequency dissemination on four links totalizing 2198 km with uncertainties below 1.1 × 10−19. The robustness of the network over two years is presented and stability and accuracy at 107 seconds integration time are finally showed.

Quality of Orbit Predictions for Satellites Tracked by SLR Stations

This study aims to evaluate and analyze the orbit predictions of selected satellites: geodetic, Global Navigational Satellite Systems (GNSS), and scientific low-orbiting, which are tracked by laser stations. The possibility of conducting satellite laser ranging (SLR) to artificial satellites depends on the access to high-quality predictions of satellite orbits. The predictions provide information to laser stations where to aim the telescope in search of a satellite to get the returns from the retroreflectors installed onboard. If the orbit predictions are very imprecise, SLR stations must spend more time to correct the telescope pointing, and thus the number of collected observations is small or, in an extreme case, there are none of them at all. Currently, there are about 120 satellites equipped with laser retroreflectors orbiting the Earth. Therefore, the necessity to determine the quality of predictions provided by various analysis centers is important in the context of the increasing number of satellites tracked by SLR stations. We compare the orbit predictions to final GNSS orbits, precise orbits of geodetic satellites based on SLR measurements determined in postprocessing, and kinematic orbits of low-orbiting satellites based on GPS data. We assess the quality degradation of the orbit predictions over time depending on the type of orbit and the satellite being analyzed. We estimate the time of usefulness of prediction files, and indicate those centers which publish most accurate predictions of the satellites’ trajectories. The best-quality predictions for geodetic satellites and Galileo reach the mean error of 0.5–1 m for the whole 5-day prediction file (for all three components), while the worst ones can reach values of up to several thousand meters during the first day of the prediction.

Quasi-Gaussian Multibeam Solar Laser Station for a Megawatt Solar Furnace

An alternative multirod solar side-pumping concept for the production of multiple quasi-Gaussian beams is proposed. This scheme was based on the One-Megawatt solar furnace in Odeillo, France, which collected and concentrated the solar light into a multilayered pyramidal pumping cavity placed at the focal zone. Each layer was comprised of a square array of four laser heads, each composed of a biconic surface that reflected the solar rays towards a Nd:YAG rod fixed inside a fused silica flow tube. A pyramidal reflector was placed inside the pumping cavity to close it and maximize the harness of solar energy. Compared to the previous multibeam solar laser station design for the same solar furnace, considerable alleviation of thermal lensing effects was achieved with the present approach, allowing the improvement of the laser beam quality factors and, consequently, the possibility of a 32-laser-beam generation, each with a quasi-Gaussian profile. For this case, 9.44 kW total laser power was calculated. Additionally, 20.01 kW total multimode laser power was numerically determined, which corresponds to a 10.93 W/m2 collection efficiency and a 2.0% solar-to-laser power conversion efficiency.

Quasi-Gaussian Multibeam Solar Laser Station for a Megawatt Solar Furnace

An alternative multirod solar side-pumping concept for the production of multiple quasi-Gaussian beams is proposed. This scheme was based on the One-Megawatt solar furnace in Odeillo, France, which collected and concentrated the solar light into a multilayered pyramidal pumping cavity placed at the focal zone. Each layer was comprised of a square array of four laser heads, each composed of a biconic surface that reflected the solar rays towards a Nd:YAG rod fixed inside a fused silica flow tube. A pyramidal reflector was placed inside the pumping cavity to close it and maximize the harness of solar energy. Compared to the previous multibeam solar laser station design for the same solar furnace, considerable alleviation of thermal lensing effects was achieved with the present approach, allowing the improvement of the laser beam quality factors and, consequently, the possibility of a 32-laser-beam generation, each with a quasi-Gaussian profile. For this case, 9.44 kW total laser power was calculated. Additionally, 20.01 kW total multimode laser power was numerically determined, which corresponds to a 10.93 W/m2 collection efficiency and a 2.0% solar-to-laser power conversion efficiency.

Analysis of the Quality of SLR Station Coordinates Determined from Laser Ranging to the LARES Satellite.

The LARES (LAser RElativity Satellite) was built by the Italian Space Agency (ASI) and launched on 13 February 2012 by the European Space Agency. It is intended for studying the Lense–Thirring effect resulting from general relativity as well as for geodynamic studies and satellite geodesy. The satellite is observed by most ground laser stations. The task of this work is to determine the station coordinates and to assess the quality of their determination by comparison with the results from the LAGEOS-1 and LAGEOS-2 satellites. Observation results in the form of normal points (396,105 normal points in total) were downloaded from the EUROLAS Data Center for the period from 29 February 2012 to 31 December 2015. Seven-day orbital arcs were computed by the NASA GSFC GEODYN-II software, determining the coordinates of seventeen selected measuring stations. The average Root Mean Square (RMS) (15.1 mm) of the determined orbits is nearly the same as for LAGEOS (15.2 mm). The stability of the coordinates of each station (3DRMS) is from 9 mm to 46 mm (for LAGEOS, from 5 mm to 15 mm) with the uncertainty of determining the coordinates of 3–11 mm (LAGEOS 2–7 mm). The combined positioning for the LARES + LAGEOS-1 + LAGEOS-2 satellites allows for the stability of 5–18 mm with an uncertainty of 2–6 mm. For most stations, this solution is slightly better than the LAGEOS-only one.

Imparting hydrophobic functionalities to copper surface using laser ablation and water emulsion of surfactants

Wettability is one of the main characteristics of a surface and reflects the ability of a liquid to flow over a solid surface. Using hydrophobic functional surfaces in evaporator and condenser of heating plants to intensify heat exchange processes will increase efficiency and, consequently, reduce the metal consumption and weight-size parameters of this equipment. This will result in reduced energy consumption and lower production and operating costs. This paper presents an analysis of methods for creating hydrophobic surfaces. The fabrication of hydrophobic copper surface of experimental samples by creating multimodal relief in form of 50 µm grid by laser ablation process and subsequent reduction of surface energy of material using water emulsion of octadecylamine is grounded and described. The fluence was varied from 5 to 900 J/cm2 when modifying the surface using laser station. The dependence of the effect of laser fluence on water contact angle value is presented. Following the study, the optimum laser irradiation parameters for the surface of experimental samples were determined, at which the maximum value of water contact angle of 146.61° and the minimum value of roll-off angle of 13.5° were obtained.

Automatic solar cell diagnosis and treatment

Solar cells represent one of the most important sources of clean energy in modern societies. Solar cell manufacturing is a delicate process that often introduces defects that reduce cell efficiency or compromise durability. Current inspection systems detect and discard faulty cells, wasting a significant percentage of resources. We introduce Cell Doctor, a new inspection system that uses state of the art techniques to locate and classify defects in solar cells and performs a diagnostic and treatment process to isolate or eliminate the defects. Cell Doctor uses a fully automatic process that can be included in a manufacturing line. Incoming solar cells are first moved with a robotic arm to an Electroluminescence diagnostic station, where they are imaged and analysed with a set of Gabor filters, a Principal Component Analysis technique, a Random Forest classifier and different image processing techniques to detect possible defects in the surface of the cell. After the diagnosis, a laser station performs an isolation or cutting process depending on the detected defects. In a final stage, the solar cells are characterised in terms of their I–V Curve and I–V Parameters, in a Solar Simulator station. We validated and tested Cell Doctor with a labelled dataset of images of monocrystalline silicon cells, obtaining an accuracy and recall above 90% for Cracks, Area Defects and Finger interruptions; and precision values of 77% for Finger Interruptions and above 90% for Cracks and Area Defects. Which allows Cell Doctor to diagnose and repair solar cells in an industrial environment in a fully automatic way.