Inspection Applications Research Articles

Multiphysics modeling and simulations of laser-sustained plasmas

Laser-sustained plasma (LSP), which can be utilized for a novel radiation light source, has advantages such as high irradiance, broad spectral range, and stable emission, demonstrating significant applications in wafer inspection in the field of the semiconductor industry. This paper revisits the historical development of LSP research and introduces fundamental physical processes in LSP. The mathematical description equations for LSP and methods of calculating plasma parameters are provided, thereby a time-dependent two-dimensional fluid model is established by taking into consideration a laser-thermal-hydrodynamic coupling effect. The propagation of the laser in plasma is investigated based on the established model, and the fundamental processes in LSP, including the initial evolution process, laser energy deposition, steady-state characteristics, and instability, are explored. The effectiveness of the simulation model is confirmed through comparing with the experimental results of high-pressure Xe LSP. The findings indicate that the mode, power, <i>F</i>-number of incident lasers, as well as parameters including components, pressure, and flow velocity of gas, can all affect the steady-state properties of LSPs. Under the identical power and <i>F-</i>number conditions, Gaussian mode laser and annular mode laser both produce LSPs with different shapes and positions. Notably, under the conditions of high-power annular laser incidence, large laser <i>F-</i>number, and high flow velocity, the simulation results reveal temporal and spatial instability in LSP. These simulation results contribute significantly to a more in-depth understanding of the underlying physical mechanisms of the LSP. Furthermore, they provide a theoretical basis for designing the light source system and optimizing the multiple parameters. The influence of laser parameters on LSP properties elucidated in this study not only advances the fundamental understanding of LSP but also offers crucial insights for designing and optimizing the light source systems in various applications, particularly in the field of optical detection for semiconductor wafer inspection.

A Review of Soft Crawling Robots with Different Driving Methods

Background: Traditional rigid robots are difficult to adapt to complex unstructured environments due to their limited degree of freedom and lack of flexibility. Therefore, soft crawling robots are concerned widely by their powerful deformation ability, infinite number of degrees of freedom, and effective interaction with humans. Objective: This paper aims to report the recent progress of soft crawling robots and provide a reference for readers in this field. Methods: By reading and summarizing the patents and papers related to soft crawling robots in recent years, they are divided into three categories according to different driving methods. The structure, motion mechanism, characteristics, and applications of each class of robots are compared and analyzed. Results: The advantages and disadvantages of each driving method are analyzed, and the key issues in soft crawling robots are pointed out. Based on this, the future development direction of this research field is predicted. Conclusion: The study shows that according to the driving method, soft crawling robots are classified as pressure driven, motor-wire driven, and soft active material driven. In addition, the characteristics of each drive are summarized. In the future, soft crawling robots will have more potential applications in biomedicine, outdoor survey, rescue search, and inspection and maintenance of equipment.

Edge Detection and Defects Checking of Binder Clip and Welded Joint using a Python-Based Algorithm: Applications in Quality Inspection

Machine vision is a computer vision system that enables a computer to work on image-based inspection and analysis for different applications. In this computer vision, a camera and sensor were used to view an image for its analysis with the help of some sort of algorithms, then processed to infer the image-based data. Machine vision systems along with Python programs can be used for many interdisciplinary applications like weld inspection, online monitoring in manufacturing auto components etc. In this study, the “Edge detection python algorithm” was developed and run through “Google Colab” notebook to inspect the edges and the boundaries of samples like faying surface-modified friction welded dissimilar joints and a binder clip (paper clamp) to check any defects or cracks and straightness etc. With the help of this Python algorithm, the edge detection was done by Sobel, Scharr, and Prewit operators. An input image of the weld joint and the binder clip were converted into Otsu’s binary threshold image. The matrix vision camera and the CMOS sensor were used in the machine vision set-up to take the images. This written algorithm is helpful to trace the edges of any kind of solids components. The edges of the binder clips and the weld joint/zone were detected. The binder clips were inspected under two different cases namely the clip in folding condition (Case I) and the binder clip in unfolding condition (Case II). The results showed a defect that was identified in the weld zone and no bending was in the binder clips. This kind of study is useful in manufacturing industries for quality inspection purposes with a new machine vision set up for online inspection of fabricated components like nuts and bolts etc.

Simple Non‐Destructive and 3D Multi‐Layer Visual Hull Reconstruction with an Ultrabroadband Carbon Nanotubes Photo‐Imager

AbstractWhile millimeter‐wave (MMW)–infrared (IR) broad photo‐imaging exhibits significant potential as an inspection technique, photo‐thermoelectric (PTE) detector operations employing carbon nanotubes (CNTs) are highly suitable because of their efficient absorption characteristics in the above bands. Such an imaging device design and the associated material coordination allow the aggregation of multiple wavelength‐specific optical information for the constituent identification of target objects in a non‐destructive manner with high sensitivity. On the other side, computer vision techniques facilitate 3D structure reconstruction as approaches from inspection methodologies, in addition to the aforementioned imaging device design. Although non‐destructive inspections require collectively satisfying both constituent identification and structural reconstruction, investigations combining MMW–IR broad photo imaging and computer vision monitoring are still insufficient. This work demonstrates computer vision‐driven simple 3D composite multi‐layer reconstructions via non‐destructive broadband multiple‐wavelength monitoring with the CNT film PTE imager. Visual hull evaluation, which is one of the representative computer vision techniques, converts 2D transmissive PTE images with different viewpoints into 3D reconstruction models. The subsequential graphical superposition of these wavelength‐specific models results in non‐destructive entire reconstructions of 3D composite multi‐layer target objects. Therefore, the present computer vision‐driven PTE broadband 3D reconstruction bridges the gap between methodologies and device design strategies toward non‐destructive inspection applications.

Plasmonic nanogrooves for SERS sensing by 3D printing

Surface enhanced Raman scattering (SERS) spectroscopy is a widely used analytical technique for detecting chemicals or biological molecules with high sensitivity and high specificity. Enhancing the sensitivity and lowering the detection limits are always the working direction of this research field. Furthermore, direct detection of low-concentration molecules in liquids remains a big challenge. In this work, we construct a SERS device consisting of periodically arranged polylactic acid (PLA) lines that are coated with silver, where the PLA line array is produced by 3D printing technique. The plasmonic nanogroove within the gap between the two adjacent PLA lines is found to be the dominant mechanism for SERS detection. A maximum enhancement factor of 2.26 × 106 has been achieved for the plasmonic nanogroove, with respect to a pure planar glass substrate. A detection limit of lower than 0.5 ppm has been research for such a sensor device in the direct detection of melamine in its aqueous solution. Furthermore, the PLA lines have advantages of biodegradability, biocompatibility, low costs, and thermo-plasticity, making the device environmentally friendly in potential applications in food safety inspection and pollutant detection in water.

Non-destructive corrosion inspection of reinforced concrete structures using an autonomous flying robot

Autonomous non-destructive testing (NDT) on reinforced concrete structures has a large potential to overcome the limitations of current routine inspection techniques, often not capable of detecting corrosion at an early stage. Here, the development and validation of two probes, tailored to acquire contact-based NDT data with the help of a hexacopter, is presented. Each probe allows the combined measurement of two essential parameters in the condition assessment: half-cell potentials and concrete electrical resistivity. Strategies are presented to monitor probe functionality during operation and detect loss of contact between probe and structure, which is considered essential for autonomous NDT. The presented approach enables effective and reliable autonomous corrosion inspection, surpassing traditional visual inspections by localizing corrosion at an early stage, allowing engineers a better planning of maintenance. The successful application in a concrete bridge inspection sets the stage for future research in autonomous inspections with robots in various fields of applications.

THE BASIC PROBLEMS AND COUNTERMEASURES OF MAP INSPECTION

Abstract. Map verification plays a crucial role in ensuring the accuracy and reliability of map data, which in turn establishes the foundation for map transparency. In China, the number of approved map inspections has been increasing annually, with a diverse range of map products being applied for inspection. Taking the example of the 'number of maps accepted for inspection' by the Ministry of Natural Resources of the People’s Republic of China, there has been a consistent upward trend in the number of accepted inspections. From 2017 to 2021, the average annual growth rate of accepted inspections exceeds 18.85%. Not only are new types, uses, and formats of map products emerging, but there is also an increase in the utilization of electronic global maps. However, challenges such as the inefficient information transfer during the inspection application process and the limited automation of technical inspections persist. Furthermore, issues related to the variability of inspection results based on individual experiences need to be addressed. To tackle these problems, this paper proposes a comprehensive technical framework for map verification based on the principles of "data sharing, business collaboration, and intelligent assistance". The objective is to establish a map verification service mechanism that promotes cross-departmental coordination and intelligent cooperation. Implementing this framework will facilitate the smooth operation of national map verification services and expedite the sharing and openness of geospatial data.

Methylammonium-Based Quasi-Two-Dimensional Perovskite Single Crystals for Highly Sensitive X-ray Detection and Imaging.

The strategy of introducing large organic cations into three-dimensional perovskites could reduce the dimensionality of perovskites to form quasi-two-dimensional (quasi-2D) perovskites, resulting in increased stability and reduced detection limits due to less ion migration. Herein, a quasi-2D perovskite single crystal (BDA)(MA)2Pb3Br10 (BDA = NH3C4H8NH3, MA = CH3NH3) with a layered structure was grown by the temperature-cooling solution method. The X-ray detector based on the (BDA)(MA)2Pb3Br10 single crystal has a sensitivity as high as 1984 μC Gy-1 cm-2 at 55.6 V/mm, and it could detect X-rays as low as 28.12 nGy s-1 at 22.2 V/mm. In addition, the X-ray imaging system based on the single-crystal device easily distinguishes between metals and plastics and exhibits a spatial resolution estimated as 250 μm, indicating the feasibility of (BDA)(MA)2Pb3Br10 crystals for X-ray imaging. This research offers a method for the design of quasi-2D layered perovskites and enhances photoelectronic applications in X-ray inspection and imaging.

Halide Perovskites and Their Derivatives for Efficient, High-Resolution Direct Radiation Detection: Design Strategies and Applications.

The past decade has witnessed a rapid rise in the performance of optoelectronic devices based on lead-halide perovskites (LHPs). The large mobility-lifetime products and defect tolerance of these materials, essential for optoelectronics, also make them well-suited for radiation detectors, especially given the heavy elements present, which is essential for strong X-ray and γ-ray attenuation. Over the past decade, LHP thick films, wafers, and single crystals have given rise to direct radiation detectors that have outperformed incumbent technologies in terms of sensitivity (reported values up to 3.5×106 µC Gyair -1 cm-2 ), limit of detection (directly measured values down to 1.5 nGyair s-1 ), along with competitive energy and imaging resolution at room temperature. At the same time, lead-free perovskite-inspired materials (e.g., methylammonium bismuth iodide), which have underperformed in solar cells, have recently matched and, in some areas (e.g., in polarization stability), surpassed the performance of LHP detectors. These advances open up opportunities to achieve devices for safer medical imaging, as well as more effective non-invasive analysis for security, nuclear safety, or product inspection applications. Herein, the principles behind the rapid rises in performance of LHP and perovskite-inspired material detectors, and how their properties and performance link with critical applications in non-invasive diagnostics are discussed. The key strategies to engineer the performance of these materials, and the important challenges to overcome to commercialize these new technologies are also discussed.

Low-cost, high-speed multispectral imager via spatiotemporal modulation based on a color camera

Spectral imaging is a powerful tool in industrial processes, medical imaging, and fundamental scientific research. However, for the commonly used spatial/spectral-scanning spectral imager, the slow response time has posed a big challenge for its employment in dynamic scenes. In this paper, we propose a spatiotemporal modulation concept and build a simple, low-cost spectral imager by combining a liquid crystal (LC) cell with a commercial color camera. By the synergic effect of temporal modulation of the LC materials and spatial modulation of the Bayer filter in a color camera, high-quality multispectral imaging is successfully demonstrated with a high rate of 8 Hz, far beyond the counterparts. Experimental results show that even with three tuning states of the LC material, optical signals with a 10-nm band can be resolved in the range between 410 and 700 nm by this method, overcoming the tradeoff between spectral resolution and time resolution. As a proof of demonstration, we present its potential usage for metamerism recognition, showing superiority over traditional color cameras with more spectral details. Considering its low cost, miniaturization and monolithic-integration ability on color sensors, this simple approach may bring the spectral imaging technology closer to the consumer market and even to ubiquitous smartphones for health care, food inspection and other applications.

Industry-Scale Application of Full-Width Digital Camera Inspection during Effective Printing on Plastic Foil at the Company "Flexograf"

The company printing plastic sheets with eight-color machines has sought help from the Faculty of Computer Science to reduce wastage of raw materials. During the study and research in this matter, it was found that the losses in raw materials are caused by the impossibility of controlling the printing through the current adequate technology that the "Flexograf" company had at its disposal. The printing on the plastic film was supervised with a digital camera with the possibility of control at a dimension of 15 [cm]. On the other hand, the width of the printed plastic film is consistently 130[cm]. Therefore, the digital control camera for control is moved along the x-axis nine times to control the printing width of 130[cm] of the plastic film. After each displacement, the digital camera was stopped for a duration of three seconds. Wherever there was a printing defect in the part that was not monitored by the digital camera and given the printing speed of the machine for a length of 400 meters of plastic sheet per minute, it caused a significant loss of raw material if there were printing defects or lack of color. This problem has been solved by replacing the 15[cm] wide inspection digital camera with a 130[cm] wide full inspection digital camera. The effect of changing the full inspections digital camera achieved the goal and reduced the raw material losses to the minimum very close to zero.

Dynamic characteristics of basalt fibre-reinforced polymer cement mortar bolts and its applicability for bolt defect detection

Basalt fiber reinforced polymer (BFRP) bolt has the advantages of high tensile strength, low quality and corrosion resistance. This kind of bolt has a potential application prospect in tunnel and underground engineering support. However, there is no effective method for non-destructive testing of anchoring quality of BFRP cement mortar, which restricts the application of this kind of anchor. Based on the propagation principle of stress waves in solids, the feasibility of the impact elastic wave method in detecting the length and compactness of bolts is theoretically demonstrated. Then, numerical simulation and test methods were used to study the propagation characteristics of stress waves in bolts under impact load and its application in the anchorage quality inspection of BFRP bolts. The results show that the elastic wave method can be used to detect the length of BFRP bolts and the detection accuracy meets the engineering requirements. In terms of anchoring compactness of cement mortar, this method can identify the location of defects, but the detection accuracy needs to be further improved. The research results presented in this paper can promote the application of BFRP bolts in tunnel and underground engineering support.

Design and Experimental Validation of an Optical Autofocusing System with Improved Accuracy

This study proposes a modified optical design to improve the issue of autofocus accuracy in existing optical systems. The proposed system uses lens offset to convert incident light into non-parallel light, achieving a focus shift and avoiding severe deformation of the light spot near the focal point of the objective lens. Based on triangulation theory and optical focusing theories such as the centroid method, the proposed optical design improves the shortcomings of existing technology. Experimental results demonstrate that the proposed optical autofocusing system has better autofocus accuracy than traditional systems while also reducing the difficulty of image processing. In summary, the proposed optical system is not only an effective autofocusing technology but also a highly valuable optical inspection and industrial application technology. This system has broader application and development opportunities for future research and practice.

High-Confidentiality X-Ray Imaging Encryption Using Prolonged Imperceptible Radioluminescence Memory Scintillators.

X-ray imaging plays an increasingly crucial role in clinical radiography, industrial inspection, and military applications. However, current X-ray imaging technologies have difficulty in protecting against information leakage caused by brute force attacks via trial-and-error. Here high-confidentiality X-ray imaging encryption by fabricating ultralong radioluminescence memory films composed of lanthanide-activated nanoscintillators (NaLuF4 : Gd3+ or Ce3+ ) with imperceptible purely-ultraviolet (UV) emission is reported. Mechanistic investigations unveil that ultralong X-ray memory is attributed to the long-lived trapping of thermalized charge carriers within Frenkel defect states and subsequent slow release in the form of imperceptible radioluminescence. The encrypted X-ray imaging can be securely stored in the memory film for more than 7 days and optically decoded by perovskite nanocrystal. Importantly, this encryption strategy can protect X-ray imaging information against brute force trial-and-error attacks through the perception of lifetime change in the persistent radioluminescence. It is further demonstrated that the as-fabricated flexible memory film enables achieving of 3D X-ray imaging encryption of curved objects with a high spatial resolution of 20 lp/mm and excellent recyclability. This study provides valuable insights into the fundamental understanding of X-ray-to-UV conversion in nanocrystal lattices and opens up a new avenue toward the development of high-confidential 3D X-ray imaging encryption technologies.

Colorimetric and photothermal dual-mode immunosensor based on Ti3C2Tx/AuNPs nanocomposite with enhanced peroxidase-like activity for ultrasensitive detection of zearalenone in cereals.

A novel peroxidase-like nanozyme has beenconstructed by decorating two-dimensional Ti3C2Tx nanosheets (Ti3C2Tx NSs) with gold nanoparticles (AuNPs) to develop a colorimetric and photothermal dual-mode immunosensor. TheTi3C2Tx/AuNPs nanocomposite-catalyzed 3,3',5,5'-tetramethylbenzidine (TMB)-H2O2 reaction system produces the one-electron oxidation product of TMB (oxTMB), which exhibits color change and strong near-infrared (NIR) laser-driven photothermal effect at 808nm laser irradiation. Given these characteristics, the developed immunosensor achieves ultrasensitive dual-mode detection of zearalenone (ZEN) by measuring colorimetric and photothermal signals with a microplate reader and a portable infrared thermometer, respectively. Under optimal working conditions, the limit of detection (LOD) of ZEN is 0.15 pg mL-1 for thecolorimetric mode and 0.48 pg mL-1 for thephotothermal mode. Inthe analysis of actual contaminated cereals samples, the test result of this method wasconsistent with that of UPLC-MS/MS. The proposed colorimetric and photothermal dual-mode immunosensor offers a new strategy for the low-cost detection of hazardous substances. Theapplication of awidely used household infrared thermometer makes the signal readout more convenient, which provides great prospects in food safety and environment inspection applications.

Aye-aye middle finger kinematic modeling and motion tracking during tap-scanning

The aye-aye (Daubentonia madagascariensis) is a nocturnal lemur native to the island of Madagascar with a unique thin middle finger. Its slender third digit has a remarkably specific adaptation, allowing them to perform tap-scanning to locate small cavities beneath tree bark and extract wood-boring larvae from it. As an exceptional active acoustic actuator, this finger makes an aye-aye’s biological system an attractive model for pioneering Nondestructive Evaluation (NDE) methods and robotic systems. Despite the important aspects of the topic in the aye-aye’s unique foraging and its potential contribution to the engineering sensory, little is known about the mechanism and dynamics of this unique finger. This paper used a motion-tracking approach for the aye-aye’s middle finger using simultaneous video graphic capture. To mimic the motion, a two-link robot arm model is designed to reproduce the trajectory. Kinematics formulations were proposed to derive the motion of the middle finger using the Lagrangian method. In addition, a hardware model was developed to simulate the aye-aye’s finger motion. To validate the model, different motion states such as trajectory paths and joint angles, were compared. The simulation results indicate the kinematics of the model were consistent with the actual finger movement. This model is used to understand the aye-aye’s unique tap-scanning process for pioneering new tap-testing NDE strategies for various inspection applications.

Miniaturized and Portable Laser Gas Sensor for Standoff Methane Detection With Non-Cooperative Targets.

A standoff methane (CH4) sensor with actual hard topographic targets (usually called non-cooperative targets) is essential for natural gas pipeline leakage inspection and many other practical applications. To address this requirement, a miniaturized and low-power-consumption gas sensor was developed based on tunable diode laser absorption spectroscopy for standoff CH4 detection with a non-cooperative target. Wavelength modulation spectroscopy with a 1f normalized 2f detection method was employed for calibration-free CH4 measurement. A Kalman filter algorithm was used to improve the precision of the detection. The performance of the standoff CH4 sensor was evaluated comprehensively under various conditions, including different incident angles, different hard topographic targets, and different standoff distances. The results show that the measurement precision is 0.107% and the sensitivity is 4.08 parts per million per meter (ppm·m) with a time resolution of 1 s and a standoff distance of 40 m. The detection limit can achieve 1.24 ppm·m at an optimal integration time of 70 s. This sensor can be easily integrated into mobile platforms, which lays the foundation for intelligent leak inspection.

THE DEVELOPMENT OF MOBILE APPLICATION FOR DENGUE SITE INSPECTION IN JOHOR BAHRU

This study focuses on developing a user-friendly mobile application for dengue site inspection, aiming to address the persistent threat of vector-borne diseases in Malaysia. The current practice of dengue site inspection is still using paper-based method, which is inefficient, prompting the need for a mobile app solution. Existing methods for identifying and destroying breeding grounds, known as Destruction Action the Breeding Place (Pemusnahan Tempat Pembiakan, PTP), face constraints due to limited technology and information facilities. This leads to incomplete eradication and the need for repeated operations in the same areas, resulting increased in operational costs. To address these issues, a simple and user-friendly mobile application is designed to enhance field data entry, enable location tracking, and provide easy access to operational data from the inspection site. To reduce the effort on site record-keeping, the application is developed on the cost-effective open-source platform - QGIS, and QField. The aim is to improve the accuracy of PTP activities based on mobile application data and increase productivity through direct data entry in the field. The objectives of this study are to identify the requirements of a mobile application for dengue site inspection, develop a mobile application with location tracking enablement, and validate the results and effectiveness of the developed mobile application. The implemented apps were tested on the field by the health officer and 98% of them agree that the application does help the process of dengue site inspection and has significantly improved their workflow. The mobile application provided them with a user-friendly interface and streamlined data entry process, allowing them to easily capture and update information during dengue site inspections. The integration of location tracking capabilities also enabled them to accurately identify and record the precise coordinates of potential breeding sites. Overall, the positive feedback from the health officers demonstrates the effectiveness and usefulness of the developed application in enhancing the efficiency and effectiveness of dengue site inspections. The application aligns with the Sustainable Development Goal of Good Health and Well-Being and contributes to the digitalization process of the Fourth Industrial Revolution (Industry 4.0), aiming at reducing long-term operating costs.

Single-pixel real-part and magnitude imaging system based on digital micromirror device

Single-pixel imaging (SPI) can capture images using a single-pixel detector. However, conventional SPI schemes only provide a magnitude image of the object, where the phase information is completely lost. Here, we present a dual-modal SPI (DMSPI) system capable of simultaneously capturing the real-part and magnitude images. Since the real-part image fuses the phase distribution, DMSPI has a strong information acquisition capability for all types of objects. The DMSPI system utilizes the two reflection arms provided by the digital micromirror device (DMD) to perform zero-frequency detection in one arm and bucket detection in the other to achieve dual-modal imaging. Benefiting from the unique modulation characteristics of DMD, the DMSPI system is simple and efficient, with high spatial resolution and fast imaging speed. Thus, it might find broad applications in biomedical diagnostics and industrial inspection.

Defect detection in carbon fiber-reinforced composites using directional dark-field imaging and tomography

This paper proposes the use of circular X-ray grating interferometry as an effective technique for defect detection with potential applications for in-line inspection of carbon fiber-reinforced pultruded profiles used inside the load-carrying spar caps of wind turbine blades. A fuzzball defect in the pultruded profile is characterized as a demonstration. The method allows for large field-of-view quantification of local fiber alignment and relative fiber volume fraction. A two-dimensional through the thickness averaged distribution of the fiber orientation, the mean scattering, and fractional anisotropy are determined. Based on this, it is possible to determine the size of the defect as well as quantify the severity of the defect.