Comparison between three scanning systems for laser cutting of airbag materials

Laser systems have been used in the practice of dentistry for >35 years. Laser systems have so many advantages, such as increase patient cooperation, reduce the duration of treatment time, and help the orthodontists to enhance the design of a patient's smile to improve treatment efficacy, and the success of orthodontic treatments can also be improved by diminishing the orthodontic pain and the discomfort of the patients. Laser systems also have some disadvantages, such as cost, large space requirements for some types, and high-risk potential for physician and patient if not used at the appropriate wavelength and power density, that is why before incorporating lasers into clinical practice, the physician must fully understand the basic science, safety protocol, and risks associated with them. Lasers have many applications in orthodontics, including accelerating tooth movement, bonding and debonding processes, pain reduction, bone regeneration, etching procedures, increase mini-implant stability, soft tissue procedures (gingivectomy, frenectomy, operculectomy, papilla flattening, uncovering temporary anchorage devices, ablation of aphthous ulcerations, and exposure of impacted teeth), fiberotomy, scanning systems, and welding procedures. In reviewing the literature on the use of laser in orthodontics, many studies have been conducted. The purpose of the present study was to give information about the use of laser in the field of orthodontics, the effects of laser during the postoperative period, and its advantages and disadvantages and to provide general information about the requirements to be considered during the use of laser.

A phase I study of nonpenetrating trabeculectomy (Zimmerman procedure) using a scanning excimer laser system was conducted to evaluate the ability of this laser system to achieve the deep dissection required to allow significant filtration without inadvertent penetration into the anterior chamber. A photopolishing, scanning 193 nm excimer laser system (LS 2000, LaserSight, Inc.) was used with a proprietary fluence, spot size, scanning pattern, and ablation shape to perform a trabeculodissection under a scleral flap with a limbal-based conjunctival flap in 8 cases of advanced glaucoma including 5 eyes that had a failed trabeculectomy. The laser trabeculodissection (LTD) was carried through Schlemm's canal and the juxtacanalicular trabecular meshwork, achieving vigorous aqueous outflow. No peripheral iridectomy was done. The scleral flap was closed loosely with a 10-0 suture. Mitomycin-C was used intraoperatively. In no case did inadvertent penetration into the anterior chamber occur. No peripheral iridectomy was performed. No intraoperative hyphema occurred. There was no postoperative iritis except minimal anterior chamber reaction in 1 eye with preoperative rubeosis. Postoperatively, a good filtering bleb was achieved in all 8 eyes with substantial reduction in the intraocular pressure without topical antiglaucoma therapy. No cases of postoperative shallowing (overfiltration) occurred. Gonioscopy, postoperatively, revealed no new peripheral anterior synechiae (PAS) to the filtration site and an intact inner trabecular meshwork. All eyes were followed for a minimum of 6 months. In this phase I study, laser trabeculodissection (LTD) with a 193 nm photopolishing, scanning system appears to be a promising alternative to full-thickness trabeculectomy, achieving significant filtration while perhaps avoiding much of the risk of filtration surgery. The laser system seemed to provide a more reliable, better-controlled dissection than a knife. The aqueous drainage seems to have acted as a self-regulating endpoint by absorbing UV energy, thus avoiding inadvertent penetration into the anterior chamber. More study is needed to establish the appropriate role of LTD in glaucoma therapy.

Laser processing is generally known for low thermal influence, precise energy processing and the possibility to ablate every type of material independent on hardness and vaporisation temperature. The use of ultra-short pulsed lasers offers new possibilities in the manufacturing of high end products with extra high processing qualities. For achieving a sufficient and economical processing speed, high average power is needed. To scale the power for industrial uses the picosecond laser system has been developed, which consists of a seeder, a preamplifier and an end amplifier. With the oscillator/amplifier system more than 400W average power and maximum pulse energy 1mJ was obtained. For study of high speed processing of large embossing metal roller two different ps laser systems have been integrated into a cylinder engraving machine. One of the ps lasers has an average power of 80W while the other has 300W. With this high power ps laser fluencies of up to 30 J/cm² at pulse repetition rates in the multi MHz range have been achieved. Different materials (Cu, Ni, Al, steel) have been explored for parameters like ablation rate per pulse, ablation geometry, surface roughness, influence of pulse overlap and number of loops. An enhanced ablation quality and an effective ablation rate of 4mm³/min have been achieved by using different scanning systems and an optimized processing strategy. The max. achieved volume rate is 20mm³/min.

Leaves on the rails compressed by the wheels of trains as well as grease and thin oxide layers form a thin layer of contamination which reduces the friction between the rail and the wheel and may also increase the electrical resistance. Conventional methods like high pressure water jetting or traction improvement by using sand do not meet the demand on process speed. For removing this contamination, a fiber coupled pulsed Nd:YAG-laser is used. In contrast to conventional optics for coating removal which use damageable scanner systems, we have developed a beam forming optics without moving parts. Thereby, a high-intensity line can be achieved that measures 15 mm x 70 µm.The laser system used for tests on the British rail net delivers 400 kW pulsed laser power at pulse durations of 60 ns and a repetition rate of 25 kHz. The tests have proven the system’s applicability to clean railheads with 30 km/h (500 m/min) and a working distance of 200 mm.Leaves on the rails compressed by the wheels of trains as well as grease and thin oxide layers form a thin layer of contamination which reduces the friction between the rail and the wheel and may also increase the electrical resistance. Conventional methods like high pressure water jetting or traction improvement by using sand do not meet the demand on process speed. For removing this contamination, a fiber coupled pulsed Nd:YAG-laser is used. In contrast to conventional optics for coating removal which use damageable scanner systems, we have developed a beam forming optics without moving parts. Thereby, a high-intensity line can be achieved that measures 15 mm x 70 µm.The laser system used for tests on the British rail net delivers 400 kW pulsed laser power at pulse durations of 60 ns and a repetition rate of 25 kHz. The tests have proven the system’s applicability to clean railheads with 30 km/h (500 m/min) and a working distance of 200 mm.

This paper presents a method of metal surface microstructuring by means of radiation of an impulse fiber laser with a scanning system, used for the displacement of the light beam. The topographic relief being presented was modeled in the graphics editor and then was manufactured on the experimental material. We also created a "parameter matrix", which allows to determine the optimal modes of operation of the laser system for treatment of a specific material. The paper describes three stages of the microstructuring process: profiling, cleaning, and polishing, and the corresponding geometrical parameters of the structures manufactured. A method for decreasing the level of relief roughness (for Ra and Rz) was developed.

Intraoperative neuromonitoring is without doubt important for all surgical interventions, where nerve structures are at risk. Mapping techniques for the identification of motor nerves and cortex are available. They rely on manual identification using an electrical stimulation probe. A landmark-based visualization of the results is currently not possible. To overcome these limitations, we are developing a system for automatic stimulation and display of functional tissue. Infrared neurostimulation (INS) was proposed to be a feasible alternative to electrical stimulation of nerves. It provides contactless and artifact-free activation of nerves. For our preclinical experiments we used an infrared diode laser system with a wavelength of 1470 nm. For automatic screening, we developed a scanning system and suitable scan-algorithms in order to provide optimal scanning parameters. Recording of compound muscle action potentials (CMAP) was performed with a differential amplifier and appropriate neurophysiologic software. Subunits of the system were combined via multiple interfaces. A control-software merges all relevant functions of the individual parts and parallel use. Marking of tissue was realized with a red pilot laser deflected by the same scanning system. With this work we could show, that a system for automatic laser deflection with parallel neurophysiologic recording and subsequent highlighting of irradiated tissue is possible. This system can serve as a tool for further systematic investigations in the field of INS.

A variety of 1064-nm laser conditioning methods were investigated to find the optimum method for production of large aperture (0.25 m2) multilayer coatings for the National Ignition Facility and Laser MegaJoule. Two conditioning methods were explored, multi-step and single-step on two different laser systems. Off-line conditioning was done on PLATO, a small beam diameter ('-1 mm) raster scanning system. On-line conditioning was done on Beamlet, a single beam prototype of the National Ignition Facility with a large rectangular beam (35 cm x 35 cm). Concurrent with this work, coating process development for low-defect density high damage threshold coatings was realized by switching from hafnia to hafnium starting materials. The results of this study suggest that single-step raster-scan off-line laser conditioning is an effective method to raise the damage threshold of multilayer mirrors deposited from hafnium and silica by reactive electron beam deposition.

Abstract. Sampling the Earth’s surface using airborne LASER scanning (ALS) systems suffers from several factors inherent to the LASER system itself as well as external factors, such as the presence of particles in the atmosphere, and/or multi-path returns due to reflections. The resulting point cloud may therefore contain some outliers and removing them is an important (and difficult) step for all subsequent processes that use this kind of data as input. In the literature, there are several approaches for outlier removal, some of which require external information, such as spatial frequency characteristics or presume parametric mathematical models for surface fitting. A limitation on the height histogram filtering approach was identified from the literature review: outliers that lie within the ground elevation difference might not be detected. To overcome such a limitation, this paper proposes an adaptive alternative based on point cloud cell subdivision. Instead of computing a single histogram for the whole dataset, the method applies the filtering to smaller patches, in which the ground elevation difference can be ignored. A study area was filtered, and the results were compared quantitatively with two other methods implemented in both free and commercial software packages. The reference data was generated manually in order to provide useful quality measures. The experiment shows that none of the tested filters was able to reach a level of complete automation, therefore manual corrections by the operator are still necessary.

Automotive safety systems like “Adaptive Cruise Control” (ACC), “Lane Change Assist” and pre-crash systems are nowadays dealing with the detection of vehicles on the road. All major upper class vehicle manufacturers like Mercedes, BMW, Chrysler and Lexus as well as leading suppliers (Bosch, Continental, Delphi) are currently developing intelligent vehicle safety systems. For vehicle environment perception many different sensors are under investigation. Well known and cheap devices like grayscale cameras are already integrated in many cars today, e.g. for parking assist functions. To meet the requirements for extremely reliable and robust environment recognition additional sensors and multi sensor data fusion approaches have to be applied. New sensors like 3-dimensional measuring multilayer laser scanner systems will be introduced in the near future to deliver environment information for these systems. By fusing multiple sensors like laser and radar systems the reliability level of automotive safety applications will be improved significantly. The paper presents an approach for the processing of the data of a multilayer laser scanner (lidar) for the detection of vehicles in road environments. The lidar data is processed using a new 3-dimensional occupancy grid. An example is given for an automotive pre-crash safety application.

Cumulative trauma disorders (CTDs) have become a growing concern in industry recently. Most assessments of the actions required by these workers have focused on crude indicators of factors that would increase the force upon tendons surrounding the wrist. However, hand intensive work, by its very nature, usually requires significant motions of the wrist that may influence tendon force. An industrial study was performed to test this hypothesis. It was found that wrist accelerations in the flexion-extension place were most closely associated with the risk of developing a carpal tunnel syndrome (CTS). These results will be reviewed and discussed relative to the wrist motions required by those in the work force that utilize laser systems such as would be found in laser based bar code scanner systems.Cumulative trauma disorders (CTDs) have become a growing concern in industry recently. Most assessments of the actions required by these workers have focused on crude indicators of factors that would increase the force upon tendons surrounding the wrist. However, hand intensive work, by its very nature, usually requires significant motions of the wrist that may influence tendon force. An industrial study was performed to test this hypothesis. It was found that wrist accelerations in the flexion-extension place were most closely associated with the risk of developing a carpal tunnel syndrome (CTS). These results will be reviewed and discussed relative to the wrist motions required by those in the work force that utilize laser systems such as would be found in laser based bar code scanner systems.

The performance of lithium-ion batteries is determined by the structural properties of the electrodes, e.g., the choice of an active material and porosity. An increase in performance is crucial for fulfilling the future requirements of various applications, such as electric vehicles and consumer electronics. Laser structuring with short and ultrashort pulses offers great potential, which has been demonstrated in many research studies. Based on already published preliminary work, which is primarily dedicated to the proof of electrochemical enhancements, requirements for the structuring process are examined. Starting from a realistic production scenario for lithium-ion electrode processing, calculations concerning the technical requirements for the laser scanner system are made. The results show high demands on usable control technology. For this reason, the development of a new type of control system is presented, which has significantly more temporal accuracy in signal transmission and thus provides the basis for fast and, at the same time, high-precision processing with pulsed laser systems.

A solid freeform fabrication (SFF) system using selective laser sintering (SLS) is currently recognized as a leading process and SLS extends the applications to machinery and automobiles due to the various materials employed. In order to develop a more elaborate and rapid system for fabricating large objects compared to existing SLS, this study employs a new selective dual-laser sintering (SDLS) process. It contains a 3-axis, dynamic focusing scanner system for scanning large areas instead of the existing fθ lens used in commercial SLS. Therefore, the unique scanning path generation is necessary to eliminate the factors of quality deterioration in case of fabricating larger objects. Also, this paper will address development of an SFF system which employs the dual laser system and the unique scanning device. Experiments were performed to evaluate the effect of a scanning path and fabrication parameters on sintering process and to fabricate the various 3D objects using polymer powder.

This paper discusses results obtained in highspeed laser micro processing of zirconium oxide ceramic and stainless steel. High-PRF (pulse repetition frequency) femtosecond laser systems were joined together with fast galvanometer scanner systems. A high average laser power (31.7 W) and fast scan speeds (17.1 m/s) were applied in order to increase material removal. The influence of average laser power, laser energy and repetition rate on both the volume ablation rate and the machining quality was studied. The maximum volume ablation rate for zirconium oxide was 70.3 µm³ per pulse, obtained with pulses of 5.9 µJ energy and 1.02 MHz. It is demonstrated that material removal on zirconium oxide will be strongly affected by heat. Stainless steel was irradiated with a maximum laser power of 31.7 W and various repetition rates. The maximum material removal rate was found to be 6.8 mm³ / min, achieved with laser pulses of 0.85 J/cm² fluence. The feasibility of the highspeed laser technology in micro processing is verified by machining examples. In addition, a demonstrator of 80 x 80 mm² was machined with a processing rate as high as 25 cm² / min.

High-precision 3D reconstruction is a core technology for visual inspection of rail track structures, playing a vital role in the timely detection of rail defects. Existing structured light 3D reconstruction methods struggle to adapt to field scanning tasks for track slabs, a large-scale infrastructure, especially the sides of the slabs, where many concealed defects endangering safe operations exist such as seam gaps, spalling, and cracks at wide-narrow joints. Addressing this challenge, a high-precision 3D reconstruction method for track slab sides based on single-line laser mobile scanning is proposed in this paper. For capturing sequential point clouds of track slab sides appropriately, we design a single-line laser dynamic scanning system comprising a 3D camera and a single-line structured light sensor first. Then, a globally optimized camera pose estimation algorithm based on spatiotemporal constraints, termed Pose-STC, is proposed. Specifically, temporal constraints enforce smoothness in translation and rotation between adjacent camera poses while spatial constraints incorporate the geometric priors of the track slab by ensuring spatial consistency of extracted structural feature points. Further, we propose a motion compensation strategy based on non-linear optimization for accurate registration frame by frame to achieve high-precision 3D reconstruction of the slab side. Comprehensive laboratory and field tests demonstrate that the proposed method delivers excellent performance, surpassing conventional methods in challenging field environments. Both coplanarity and collinearity measurements achieve sub-millimeter accuracy, meeting the precision inspection requirements for track slabs.

Previous studies have shown that reflectance imaging at wavelengths greater than 1200-nm can be used to image demineralization on tooth occlusal surfaces with high contrast and without the interference of stains. In addition, these near-IR imaging systems can be integrated with laser ablation systems for the selective removal of carious lesions. Higher wavelengths, such as 1950-nm, yield higher lesion contrast due to higher water absorption and lower scattering. In this study, a point-to-point scanning system employing diode and fiber lasers operating at 1450, 1860, 1880, and 1950-nm was used to acquire reflected light images of the tooth surface. Artificial lesions were imaged at these wavelengths to determine the highest lesion contrast. Near-IR images at 1880-nm were used to demarcate lesion areas for subsequent selective carious lesion removal using a new compact air-cooled CO2 laser prototype operating at 9.3-µm. The highest lesion contrast was at 1950-nm and the dual NIR/CO2 laser system selectively removed the simulated lesions with a mean loss of only 12-µm of sound enamel.