Laser Position Research Articles

Characterization of Arboblend V2 Nature Textured Surfaces Obtained by Injection Molding

Surface texturing is an engineering technology used in order to improve the surface characteristic of plastic parts obtained by injection molding. Applying this process not only changes the part surface properties, but also its topography. The novel functionalities of plastic products become useful when other materials make contact with the textured surface. Of course, these characteristics may vary depending on the laser positioning, dimensions, and geometry of the texture. The present paper presents the surface characteristics obtained after the laser texturing of the Arboblend V2 Nature biodegradable polymer. Three distinct geometries were studied: hexagonal, square, and triangular, and different behaviors of them were highlighted during surface free energy (SFE) and contact angle (WCA) measurements: a hydrophobic character for square and hexagonal geometry with distilled water as the measure liquid, and a hydrophilic character with diiodomethane as the measure liquid; for triangle geometry, the contact angle measurements were impossible to extract because the drop turns into a flat puddle. Additionally, the friction coefficient varied depending on the geometry texture, with the lowest value being recorded by the sample with hexagonal geometry. The micro-indentation tests highlighted increased surface micro-hardness compared to the basic material. The possibility of use in the practice of textured surfaces is viable; thus, based on the obtained results, there is even the possibility to replace non-biodegradable polymers from different sectors of activity.

Fast and accurate centerline extraction algorithm for a laser stripe applied for shoe outsole inspection.

Line laser 3D reconstruction technology is widely used in industrial applications. As a key step of this technology, line laser midline extraction directly affects the accuracy of the 3D reconstructed model. In reconstructing the shoe outsole, the traditional algorithm based on the threshold method to determine the laser position may result in a large amount of information loss and miscellaneous point misjudgment owing to the irregularity of the shoe outsole surface, which critically affects the laser imaging quality. To address this problem, an algorithm based on the QQ plot inspection of the laser has been proposed. The QQ plot is a scatter plot, the abscissa is usually the quantile of the standard normal distribution, and the ordinate is the quantile of the data to be tested. If the points on the scatter plot tend to be straight lines, the data to be tested is in a normal distribution. Based on this property, the proposed algorithm aims to check whether the pixels of the image column tend to be normally distributed, rather than using traditional thresholding methods to locate the laser. The objective is to examine whether the image column pixel distribution is normal, instead of using the traditional threshold method to locate the laser. However, the calculation speed of this method is extremely low. To enhance the efficiency of testing the normality of the QQ plot, a quantile-repetition (Q-R) test method is proposed. In this approach, the degree of repetition of quantiles and the position of Q-R values are used to replace the QQ plot based evaluation of the points being on a straight line, and the exact center position is determined by the GGM. The experimental results show that the proposed algorithm can extract more effective points and fewer invalid points of the laser compared to those obtained using the traditional approach, in a rapid, stable, and accurate manner.

High color rendering and high-luminance laser lighting using all inorganic nitride phosphor films.

Despite the huge advances that have been made in the development of ultra-high luminance laser lighting, achieving high color rendering properties in such systems at the same time remains a challenge. Recent studies show that in most cases, the luminous efficacy (LE) of laser lighting is compromised to improve the color rendering index (CRI). In this study, a possible solution to this problem has been proposed by preparing phosphor-in-glass (PiG) films comprised of the yellow-emitting phosphor (LSN:Ce3+) and the red-emitting phosphor (CASN:Eu2+). The composite material synthesized in this study exhibited outstanding optical and thermal properties. A uniform white light with a high CRI of 80.0 and a high LE of 185.9 lm W-1 was achieved by optimizing the yellow/red ratio and the emission peak position of the blue laser. Furthermore, it was found that this design enabled the phosphor to restrict the light emission area effectively, thus attaining a high luminous exitance of 1302 lm mm-2. With their superior optical performance, the PiG films can be regarded as promising color converter candidates for future high-quality laser-based white light sources.

Технологии и технические средства рекультивации залежных земель с регулированием уровня увлажненности почвы

An assessment of the technological feasibility of the tasks of involving fallow lands in agricultural circulation and increasing the fertility of agricultural land in the long-term period of economic activity is given. Insufficient information content of the use of yield maps for assessing the fertility of fields has been revealed. It is proposed to use maps of the relief of fields, which will allow establishing the dynamics of violation of the water-air regime of the soil. It is substantiated that in the process of involving fallow lands into circulation, it is required to introduce a technological operation of micro topographic analysis of the degree of soil moisture. An algorithm for switching on the field leveling operation (surface leveling of the field plane) using modern positioning systems has been developed. It was revealed that leveling the field with a laser level made it possible to reduce yield fluctuations by 20% within the cultivated area of the field and increase yield by 25‑30% (an example of sowing corn). Shortcomings of positioning accuracy with the use of laser and satellite positioning have been established. It is proposed to transfer digital information transmission modules to network clusters with the choice of the best digital data transmission channel by including an uninterrupted positioning module with digital data transmission over a 434 MHz and 864 MHz radio channel with a range of up to 600 meters to other digital information transmission modules of the vehicle positioning. A plan for the implementation of the concept of forming a digital field on the basis of a field experimental station of the RSAU-MAA named after C.A. Timiryazev, with the aim of creating a frontier for the sustainable development of closed life cycle technologies through the introduction of innovations using the multiplicative interaction of mechatronic systems and telematics for agro-industrial complex equipment

Recultivation of fallow lands with soil moisture regulation

The technologies for implementing the tasks of involving fallow lands in agricultural turnover and increasing the fertility of agricultural lands in the long-term period of economic activity are highlighted. Insufficient informativeness of the use of yield maps to assess the fertility of fields has been revealed. It is proposed to use field relief maps to establish the dynamics of violation of the water-air regime of the soil. It is proved that in the process of involving fallow lands into circulation, it is necessary to introduce a technological operation of microtopographic analysis of the degree of soil moisture. An algorithm for enabling the operation of levelling of field surface (removal of relief) using modern positioning systems has been developed. It was revealed that the levelling of the field with a laser level allowed to reduce yield fluctuations by 20% within the crop acres of the field and increase yield by 25-30%. Disadvantages of positioning accuracy with the use of laser and satellite positioning have been established. It is proposed to transfer digital information transmission modules to network clusters with the choice of the best digital data transmission channel by including an uninterrupted positioning module with digital data transmission over a 434 MHz and 864 MHz radio channel with a range of up to 600 meters to other modules for providing digital positioning information to the machine. The plan of implementation of the concept of digital field formation on the basis of the field experimental station of the Russian State Agrarian University - Moscow Timiryazev Agricultural Academy is presented, with the aim of creating a frontier for the sustainable development of closed-life cycle technologies through the introduction of innovations using multiplicative interaction of mechatronic systems and telematics for agricultural technology.

지속가능한 디자인에 기초한 골판지 가구의 설계 및 전략 연구

As a kind of paper material, corrugated paper has light weight, good mechanical properties, can be recycled, has good printability, and is not harmful to the environment. Therefore, it is feasible to promote corrugated cardboard furniture. Through the analysis of corrugated paper furniture cases, this thesis proposes sustainable design strategies for cardboard furniture and divides the design process of paper furniture into design stage - use stage - post-use stage, proposes reduction control in the design stage, and provides specific implementation plans, such as in the design stage, using a computer to conduct a corrugated paper furniture model For example, in the design stage, finite element analysis is performed on the corrugated furniture model by computer, which enables a more reasonable structural design that meets the mechanical requirements of the furniture structure while maximizing material savings. In the processing stage, a cutting machine with automatic laser positioning is introduced to accommodate the processing of corrugated paper shaped structures and achieve sustainable design from the perspective of waste reduction. Reuse guidance in the use phase and recyclable technology support in the post-use phase are also proposed, as well as implementation strategies for specific elements of each link.It is hoped that this will bring positive implications for the market, resources, and the environment, and will provide certain valuable references and insights for industry players in the design and production of corrugated furniture.

Micro-Robotic Medical Tools Employing SMA Actuators for Use in the Human Body

Several micro-robotic medical tools, including catheters, guide wires, and endoscopes, employing shape memory alloy (SMA) actuators have been proposed and developed for use in the human body. This paper describes the basic principle of SMAs and the characteristics of several mechanisms, such as unidirectional bending, multi-directional bending, torsional movement, extension, and stiffness control. Moreover, some medical applications, such as insertion assistance and endoscopic and laser positioning, are described.

Fast optical‐writing recognition based on two‐dimensional photothermoelectric effect assisted with deep learning

AbstractThe photothermoelectric (PTE) effect enables a simple structure to construct a noncontact and self‐powered writing device. PTE detectors based on active materials and one‐dimensional (1D) position‐sensitive PTE effect have attracted considerable attentions. However, there is no research on applying the 1D position‐sensitive PTE effect to a two‐dimensional (2D) surface. Besides, flexible writing devices based on the PTE effect have not been reported. Here, we demonstrate a self‐powered flexible optical writing device based on the 2D position‐sensitive PTE effect of SnSe thin film. Laser positioning, tracking, and distinguishing of optically written characters have been realized by only measuring the bi‐directional output voltages during the writing process. A deep convolutional neural network has been introduced to recognize optically written numbers and characters with high recognition accuracy (92%) and fast processing speed (8.6 ms). The flexible optical‐writing device with a simple structure could rapidly and accurately recognize characters in a noncontact fashion using a small amount of training data.image

Investigation on small volume and long optical path multipass cell using differential evolution algorithm

AbstractTo solve the contradiction between high performance and portability of tunable diode laser absorption spectroscopy (TDLAS) systems, we propose a multipass cell (MPC) design method based on differential evolution (DE) algorithm, and realize intelligent optimization design of MPC with small volume and long optical path. MPC is the core component of the TDLAS system. The optical path of MPC determines the detection accuracy of the TDLAS system. The optical path is affected by the position and angle of incident laser, mirror spacing, and other parameters. The DE algorithm is used to optimize the parameters that affect the performance of MPC, and a compact MPC with a spherical mirror diameter of 25.4 mm, a laser reflection number of 183, an optical path of 5.98 m, and a mirror spacing of 31.7 mm is designed. Under the same spherical mirror condition, the detection limit of MPC designed based on the DE algorithm is increased from 0.91 to 0.76 ppm compared with the MPC commonly used seven‐ring spot pattern. This has a guiding and exemplary role in the design and development of high space utilization MPC.

Sensor fusion of pyrometry and acoustic measurements for localized keyhole pore identification in laser powder bed fusion

In-situ process monitoring as an aid to part qualification for laser powder-bed fusion ( L -PBF) technology is a topic of increasing interest to the additive manufacturing community. In this work, airborne acoustic and inline pyrometry measurements were recorded simultaneously with the laser position. X-ray radiography imaging was used to spatio-temporally register keyhole pore locations to the pyrometry and acoustic signals, enabling binary labeling of data partitions based on pore formation. These labeled partitions were subsequently featurized using a highly comparative time-series analysis toolbox. Acoustic data was found to be much more effective than the pyrometry data for keyhole pore identification. However, when the information contained in both sensing modalities was combined in a sensor fusion strategy, the error rates of the top performing models were significantly reduced.

Motion detection and correction for carotid MRI using a markerless optical system

PurposeMotion related artifact is a challenge for MRI, especially when imaging regions like the carotid artery where complex motion (abrupt and bulk motion) may occur. This study aims to develop a non-contact motion detection and correction system for carotid MRI using a markerless optical tracking system. MethodsThe proposed markerless optical tracking system consisted of a cross-line laser, an MRI-compatible camera and plastic holders mounted inside the scanner bore. The neck motion of the subject can be captured by monitoring the change of the projected laser position in real-time. The system was used to correct both abrupt motion and bulk motion for carotid MRI. The abrupt motion (e.g. coughing) was compensated by discarding the corrupted k-space lines and re-estimating the missing lines using SPIRiT algorithm. The bulk motion was corrected by phase adjustment of k-space lines according to the measured 1D-translational bulk motion (along anterior-posterior direction) and optimized in-plane translation parameters. Ten volunteers underwent carotid MRI with real-time neck motion detection and retrospective motion correction. Artery sharpness, vessel wall thickness and overall image quality score were compared between the motion-corrupted image and motion-corrected images of different correction strategies. ResultsBoth the abrupt motion and the bulk motion during carotid scanning were successfully detected and corrected. The results of ten volunteers demonstrated significant improvement in carotid artery sharpness, vessel wall thickness measurement, and overall image quality score using the proposed markerless optical tracking system and motion correction strategies. ConclusionThe proposed markerless structured light based motion detection and correction system can sensitively detect both abrupt and bulk motion during carotid MR scans. By correcting for both abrupt and bulk motion, vessel wall delineation was improved in carotid MR images, which could potentially facilitate carotid plaque identification and atherosclerosis diagnosis in the future.

Underwater optical guiding and communication solution for the AUV and seafloor node.

In this paper, an optical guiding and docking scheme is designed, and a node integrating laser positioning guidance and communication functions is developed. Through experiments, it is verified that the laser docking system has the function of guiding and communicating the autonomous underwater vehicle (AUV) with the support of the seabed observation network. It can provide two-dimensional position information for underwater platforms to navigate the media to sea network nodes and enable visual contact between them. The integrated terminals are small enough (6 cm in diameter) to be installed on small underwater platforms, such as AUVs. To safely work at a depth of thousands of meters, the devices have cylindrical shapes rather than spherical shapes. However, the cylindrical shell confines the view angle of the receiver. An optical system and a photodiode array are adopted to enlarge the cylindrical-shaped receiver's view angle. The positioning algorithm is designed based on the optical lens system and the photodiode array. In a small-pool experiment, this system is tested to achieve a data rate of 1 Mbit/s at a distance of 4 m. Positioning algorithms are also confirmed preliminarily in the small-pool experiment, and the error of the positioning algorithm is discussed.

Process Monitoring Using Synchronized Path Infrared Thermography in PBF-LB/M.

Additive manufacturing processes, particularly Laser-Based Powder Bed Fusion of Metals (PBF-LB/M), enable the development of new application possibilities due to their manufacturing-specific freedom of design. These new fields of application require a high degree of component quality, especially in safety-relevant areas. This is currently ensured primarily via a considerable amount of downstream quality control. Suitable process monitoring systems promise to reduce this effort drastically. This paper introduces a novel monitoring method in order to gain process-specific thermal information during the manufacturing process. The Synchronized Path Infrared Thermography (SPIT) method is based on two synchronized galvanometer scanners allowing high-speed and high-resolution observations of the melt pool in the SWIR range. One scanner is used to steer the laser over the building platform, while the second scanner guides the field of view of an IR camera. With this setup, the melting process is observed at different laser powers, scan speeds and at different locations with respect to the laser position, in order to demonstrate the positioning accuracy of the system and to initially gain thermal process data of the melt pool and the heat-affected zone. Therefore, the SPIT system shows a speed independent overall accuracy of ±2 Pixel within the evaluated range. The system further allows detailed thermal observation of the melt pool and the surrounding heat-affected zone.

An evaluation of quality assurance guidelines comparing the American College of Radiology and American Association of Physicists in Medicine task group 284 for magnetic resonance simulation.

PurposeThe purpose of this study was to evaluate similarities and differences in quality assurance (QA) guidelines for a conventional diagnostic magnetic resonance (MR) system and a MR simulator (MR‐SIM) system used for radiotherapy.MethodsIn this study, we compared QA testing guidelines from the American College of Radiology (ACR) MR Quality Control (MR QC) Manual to the QA section of the American Association of Physicists in Medicine (AAPM) Task Group 284 report (TG‐284). Differences and similarities were identified in testing scope, frequency, and tolerances. QA testing results from an ACR accredited clinical diagnostic MR system following ACR MR QC instructions were then evaluated using TG‐284 tolerances.ResultsFive tests from the ACR MR QC Manual were not included in TG‐284. Five new tests were identified for MR‐SIM systems in TG‐284 and pertained exclusively to the external laser positioning system of MR‐SIM systems. “Low‐contrast object detectability” (LCD), “table motion smoothness and accuracy,” “transmitter gain,” and “geometric accuracy” tests differed between the two QA guides. Tighter tolerances were required in TG‐284 for “table motion smoothness and accuracy” and “low contrast object detectability.” “Transmitter gain” tolerance was dependent on initial baseline measurements, and TG‐284 required that geometric accuracy be tested over a larger field of view than the ACR testing method. All tests from the ACR MR QC Manual for a conventional MR system passed ACR tolerances. The T2‐weighted image acquired with ACR sequences failed the 40‐spoke requirement from TG‐284, transmitter gain was at the 5% tolerance of TG‐284, and geometric accuracy could not be evaluated because of required equipment differences. Table motion passed both TG‐284 and ACR required tolerances.ConclusionOur study evaluated QA guidelines for an MR‐SIM and demonstrated the additional QA requirements of a clinical diagnostic MR system to be used as an MR‐SIM in radiotherapy as recommended by TG‐284.

Actuator and Contact Force Modeling of an Active Soft Brace for Scoliosis.

Scoliosis is an abnormality of the spinal curvature that severely affects the musculoskeletal, respiratory, and nervous systems. Conventionally, it is treated using rigid spinal braces. These braces are static, rigid, and passive in nature, and they (largely) limit the mobility of the spine, resulting in other spinal complexities. Moreover, these braces do not have precise control over how much force is being applied by them. Over-exertion of force may deteriorate the spinal condition. This article presents a novel active soft brace that allows mobility to the spine while applying controlled corrective forces that are regulated by varying the tensions in elastic bands using low-power light weight twisted string actuators (TSAs). This article focuses on the actuator and contact force modeling of the active soft brace (ASB). The actuator modeling is required to translate the twisting of string in terms of contraction of the string’s length, whereas the contact force modeling helps in estimating the net resultant force exerted by the band on the body using single point pressure/force sensors. The actuators (TSAs) are modeled as helix geometry and validated using a laser position sensor. The results showed that the model effectively tracked the position (contraction in length) with root mean square error (RMSE) of 1.7386 mm. The contact force is modeled using the belt and pulley contact model and validated by building a custom testbed. The actuator module is able to regulate the pressure in the range 0–6 Kpa, which is comparable to 0–8 Kpa pressure regulated in rigid braces. This makes it possible to verify and demonstrate the working principle of the proposed active soft brace.

Least-Square-Method-Based Optimal Laser Spots Acquisition and Position in Cooperative Target Measurement.

The relative positioning precisions of coordinate points is an important indicator that affects the final accuracy in the visual measurement system of space cooperative targets. Many factors, such as measurement methods, environmental conditions, data processing principles and equipment parameters, are supposed to influence the cooperative target’s acquisition and determine the precision of the cooperative target’s position in a ground simulation experiment with laser projected spots on parallel screens. To overcome the precision insufficiencies of cooperative target measurement, the factors of the laser diode supply current and charge couple device (CCD) camera exposure time are studied in this article. On the hypothesis of the optimal experimental conditions, the state equations under the image coordinates’ system that describe the laser spot position’s variation are established. The novel optimizing method is proposed by taking laser spot position as state variables, diode supply current and exposure time as controllable variables, calculating the optimal controllable variables through intersecting the focal spot centroid line and the 3-D surface, and avoiding the inconvenience of solving nonlinear equations. The experiment based on the new algorithm shows that the optimal solution can guarantee the focal spot’s variation range in 5–10 pixels under image coordinates’ system equivalent to the space with a 3 m distance and 0.6–1.2 mm positioning accuracy.

Detection of keyhole pore formations in laser powder-bed fusion using acoustic process monitoring measurements

In-situ process monitoring of additively manufactured parts has become a topic of increasing interest to the manufacturing community. In this work, acoustic measurements recorded during laser powder-bed fusion (L-PBF) were used to detect the onset of keyhole pores induced by the lasing process. Post-build radiography was used to identify the locations of keyhole pores in the build. The pore locations were spatially and temporally registered with the recorded time-series of laser position and acoustic pressure to identify specific partitions of the acoustic signals which correspond to pore formation. Ensemble empirical mode decomposition, traditional Fourier decomposition, and statistical measures of the time-series and corresponding frequency spectra were used to extract feature vectors which correlate to keyhole pore formation. Sequential feature selection revealed that measures associated with the acoustic spectra were most useful for identifying pore formations in L-PBF. A subset of the most informative data features was used to train a support vector machine model to predict pore formation with up to 97% accuracy.

An analytical model to calculate the primary and secondary acoustic forces acting on microbubbles due to a short pulsed laser excitation

This work presents a comprehensive analytical approach to describe photoacoustic waves resulting from a pulsed laser excitation. The spatial part of the laser is modeled by a zeroth-order Bessel function of the first kind, which has a wide range of applications in optics and medical physics, such as optical trapping and nonlinear effects resulting from the interaction of a pulsed laser with tissue in photoacoustic imaging. The temporal part of the laser is described by a Gaussian function, which is a pretty realistic approximation since the interaction of the laser with the medium is instantaneous. The photoacoustic wave equation is solved analytically using the Fourier transform and the Greens’ function methods. The solution of the photoacoustic wave equation depends explicitly on position, time, pulse duration, and beam-width of the pulsed laser. The effects of these dependencies on the photoacoustic wave are investigated. Later, the primary and secondary radiation forces acting on microbubbles Albunex and Quantison are calculated using the magnitude of the photoacoustic pressure wave. The primary and secondary radiation forces decrease considerably with the distance from the photoacoustic absorber. These forces increase as the beam-width increases while they decrease as the pulse duration gets longer. The primary radiation forces on the microbubbles are on the order of nanonewtons. The force at this scale can be used to manipulate microbubbles. The secondary radiation force between identical microbubbles is in the range of piconewtons. Hence, this force can be used to determine the viscoelastic properties of microbubbles even though it is very small compared to the primary radiation force. The radiation forces determined by this work are also compared with those calculated by another study describing the laser’s spatial profile with a Gaussian function. The forces obtained by this work are larger than the forces determined by the Gaussian function approximation at the positions near the source. The forces obtained by the two approaches show similar behaviors, and they decrease remarkably with the distance from the source. Thus, the model presented in this work can be used to study the nonlinear mechanism in photoacoustics, such as enhancing image contrast and determining the tissue temperature. It can also be helpful for the applications of microbubbles in medical imaging and drug delivery as carriers.

ALPS/IMU calibration method based on spatial multipose transformation for large space indoor dynamic positioning

Accurate laser positioning system (ALPS) is widely used in large space indoor dynamic positioning. To improve the positioning accuracy and refresh frequency, the inertial measurement unit (IMU) with a high frame rate is used for fusion, so it is necessary to calibrate the external parameters of ALPS and IMU. Based on the analysis of the calculation process and error description of traditional calibration, we propose a calibration method of spatial multipose transformation (SMT). In this calibration method, the target plate performs multiple attitude transformations to obtain the attitude data and process its error. Then, the Lodrigues matrix is introduced in the solution process to reduce the dimension of unknown variables in the equation, and it is optimized combined with SVD decomposition. At the same time, to further adapt to the application of fusion, a more intuitive error description method is proposed to evaluate the influence of calibration results on fusion accuracy. The simulation experiments indicate that the proposed method enables the calibration error to have accuracy within 0.02 mm. Furthermore, the results of the validation experiments show that the proposed calibration solution method improves in accuracy and robustness with respect to the conventional method. It provides a technical basis for realizing higher precision indoor dynamic positioning applications in large space.

Robotic laser position versus freehand in CT-guided percutaneous microwave ablation for single hepatocellular carcinoma (diameter < 3 cm): a preliminary study

Purpose To compare the accuracy and safety of robotic laser position (RLP) versus freehand for antenna CT-guided microwave ablation (MWA) of single hepatocellular carcinoma (HCC) (diameter < 3 cm). Materials and methods This retrospective study was conducted between May 2020 and June 2021. A total of 40 patients with early HCC who underwent CT-guided MWA were divided into two groups: a freehand group (n = 20) and a RLP group (n = 20). Based on in-plane and out-of-plane data, the actual puncture point error (APPE), number of repositioning procedures, and operative duration were compared using the Mann–Whitney U test. Ablation-related complications were compared using the Chi-squared test. Results The mean diameter of HCC patients who received MWA was 2.4 ± 0.5 cm. For in-plane APPE, APPE was comparable between the two groups (p = 0.299). However, for the out-of-plane position, the APPE in the freehand group was higher than that in the RLP group (p = 0.027). The number of repositioning procedures was 0 (range, 0–0) for RLP-guided procedures and 3 (range, 2–5) for freehand procedures, showing a statistically significant difference between the two groups (p < 0.001). The mean operative duration for freehand procedures was 39 min, compared with 26 min for RLP-guided procedures, showing a significant difference (p = 0.013). No deaths or major complications were directly related to MWA. Minor complications in the freehand group were comparable with those in the RLP group (p = 0.313). Conclusion RLP guidance significantly reduces the number of antenna repositioning procedures in MWA and improves puncture accuracy for target HCC out-of-plane. In addition, the operative duration of robotic guidance was shorter than that of freehand guidance.