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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.

To meet the demands of high-frequency wireless communications and Internet of Things (IoT) applications, modern integrated circuit (IC) packages should support operating frequencies in the GHz range and be implemented on fine substrate structures. Glass has many advantages as an interposer material for three-dimensional IC (3D-IC) designs, including tunable electrical and mechanical properties, amenability to large-scale processing, and high optical transparency in the visible range. Moreover, glass is easily processed to produce the through-glass vias (TGVs) required to realize high-frequency circuit designs and microelectromechanical systems devices. The present study proposes a method for patterning TGVs on glass substrates via a nonlinear multiphoton-assisted modification process performed using single-pulse irradiation by a 1030-nm picosecond laser. A theoretical model is additionally proposed to describe the glass substrate modification mechanism induced by the nonlinear multiphoton excitation effect. The feasibility of the proposed method is demonstrated by patterning a TGV array with a high aspect ratio of 1:10 and a taper angle of ∼2° on a Corning SGW3 glass substrate.

Commercial laser interferometers are conventionally used to measure the positioning error of a long linear stage in multiaxis computer numerical control machine tools. However, commercial laser interferometers are costly and difficult to use. Therefore, a low-cost photodetector-based heterodyne interferometer combined with an electronic phasemeter module was proposed for precise measurement of the positioning error of a long linear stage. The proposed heterodyne interferometer was combined with a virtual electronic phasemeter that employs a self-developed signal-processing technique. Our core algorithm and proposed photoelectric-signal-processing technique were developed using the LabVIEW human–machine interface. Moreover, to verify the performance of the proposed heterodyne interferometer, a laboratory-built prototype was constructed and used to measure the positioning error of a long linear stage. The experimental results indicated that the positioning accuracy of the proposed interferometer was ±4.5 μm for a linear stage with a displacement of 250 mm; the results obtained were comparable to those obtained with a commercially available laser interferometer. The proposed heterodyne interferometer can thus be used in other applications related to precision engineering.

For automated optical inspection, autofocusing microscopes play an important role in capturing clear images of the measured object. At present, the image processing part of optics-based autofocusing microscopes often has various factors, which makes it impossible to describe the image information of the semicircular (or elliptical) spot with a simple circle-finding method. Accordingly, this study has developed a novel algorithm that can quickly calculate the ideal center of the elliptical spot and effectively compensate the linearity of the focusing characteristic curve. A prototype model was used to characterize and verify the proposed algorithm. The experimental results show that by using the proposed algorithm, the autofocusing accuracy can be effectively improved to less than 1.5 μm.

In order to improve the quality of the laser and shorten the optical path of the fast steering mirror (FSM) laser compensation system, this paper proposes a four-degrees-of-freedom (4-DOF) voice coil motor (VCM) with the function of reducing laser geometrical fluctuations. The feature of this paper is the combination of a DC brushed spindle motor and the proposed 4-DOF VCM. A diffuser is installed on the shaft of the DC brushed motor for suppressing the laser speckle. The proposed 4-DOF VCM is combined with a laboratory-designed mirror set, controlling the laser direction to compensate for laser fluctuations. The proposed actuator was designed and verified by using the commercial CAD software SolidWorks and finite element analysis (FEA) software ANSYS. A mathematical model was built to simulate the dynamic response of the proposed 4-DOF VCM in MATLAB Simulink.

Laser beams can fluctuate in four directions, which requires active compensation by a fast steering mirror (FSM) motion system. This paper deals with the design of four-degrees-of-freedom (DoF) compliant parallel manipulators, for responding to the requirements of the FSM. In order to simplify high-precision control in parallel manipulators, maximum kinematic decoupling is always desired. A constraint map method is used to propose the four required DoF with the consideration of maximum kinematic decoupling. A specific compliant mechanism is presented based on the constraint map, and its kinematics is estimated analytically. Finite element analysis demonstrates the desired qualitative motion and provides some initial quantitative analysis. A normalization-based compliance matrix is finally derived to verify and demonstrate the mobility of the system clearly. In a case study, the results of normalization-based compliance matrix modelling show that the diagonal entries corresponding to the four DoF directions are about 10 times larger than those corresponding to the two-constraint directions, validating the desired mobility.

With the ever-changing nature of technology and the vigorous development of artificial intelligence, traditional fishery has gradually transformed into smart aquaculture. The current smart sensing instruments on the market can accurately measure water quality parameters for fish farms, but they are too expensive to be used popularly. On the basis of the mobile application developed by Taijiang Agriculture Biotechnology, a local company of Taiwan, and our empirical cumulative trend, we propose a smart technology for monitoring water quality in fish farms using a cellphone camera sensor. By the proposed method, we captured and recorded the RGB values of the water color using a cellphone camera sensor. At the same time, we measured the water quality parameters using a spectrophotometer and a Secchi disk at four fish farms. As a result of experimental design and analysis, we found an obvious correlation between water color and various water quality parameters. In the future, we expect to achieve the target that fishermen can use a cellphone to obtain real-time water quality information by utilizing the proposed low-cost and efficient aquaculture technology. [ABSTRACT FROM AUTHOR]

Multi-DOF motion is realized in the eyes and joints of robots mostly through the combination of multiple one-degree-of-freedom (1-DOF) motors. However, this results in reduced efficiency, a large volume, reduced response speed, and inaccurate positioning. To solve these problems, this study proposes a novel 3-DOF spherical voice coil motor (VCM). In this VCM, 16 coils and a radially oriented ring magnet are used to generate a Lorentz force to achieve motion. In particular, coils for Z-axis rotation are sandwiched between the coils for X- and Y-axis rotation. Furthermore, the proposed VCM can achieve 360° rotation about the Z-axis. The commercial software ANSYS was used to design and verify the performance of the proposed VCM. Simulation results indicate that this VCM affords improved power efficiency because only a suitable combination of coils, rather than all coils, needs to be powered on. The results demonstrate the feasibility of the proposed 3-DOF spherical VCM.

In keeping with consumers’ preferences for electromagnetic motors of ever smaller power consumption, it is necessary to improve the power efficiency of the electromagnetic motors used in unmanned aerial vehicles and robots without sacrificing their performance. Three-degree-of-freedom (3-DOF) spherical motors have been developed for these applications. Accordingly, this study modifies the 3-DOF spherical motor proposed by Hirata’s group in a previous study (Heya, A.; Hirata, K.; Niguchi, N., Dynamic modeling and control of three-degree-of-freedom electromagnetic actuator for image stabilization, IEEE Transactions on Magnetics 2018, 54, 8207905.) to accomplish a 3-DOF spherical motor for camera module with higher torque output in the large rotation angle. The main contribution of this study is to improve the static torque in the X- and Y-axes with an improved electromagnetic structure and a particular controlling strategy. In the structural design, eight symmetrical coils with specific coil combination are used instead of conventional four symmetrical coils. In this study, the development of the proposed 3-DOF spherical motor was constructed and verified by using a 3D finite-element method (3D FEM). The simulation results show that the proposed 3-DOF spherical motor has higher torque output in the large rotation angle when compared to the original 3-DOF spherical motor.

This paper proposes a system utilizing a Renishaw XL80 positioning error measuring interferometer and sensitivity analysis design to measure six-degree-of-freedom (6 DOF) geometric errors of a machine tool’s linear guide. Each error is characterized by high independence with significantly reduced crosstalk, and error calculations are extremely fast and accurate. Initially, the real light path was simulated using Zemax. Then, Matlab’s skew ray tracing method was used to perform mathematical modeling and ray matching. Each error’s sensitivity to the sensor was then analyzed, and curve fitting was used to simplify and speed up the mathematical model computations. Finally, Solidworks was used to design the set of system modules, bringing the proposed system closer to a product. This system measured actual 6 DOF geometric errors of a machine tool’s linear guide, and a comparison is made with the Renishaw XL-80 interferometer measurements. The resulting pitch, yaw, horizontal straightness, and vertical straightness error deviation ranges are ±0.5 arcsec, ±3.6 arcsec, ±2.1 μm, and ±2.3 μm, respectively. The maximum repeatability deviations for the measured guide’s pitch, yaw, roll, horizontal straightness, vertical straightness, and positioning errors are 0.4 arcsec, 0.2 arcsec, 4.2 arcsec, 1.5 μm, 0.3 μm, and 3 μm, respectively.

For optical image stabilization (OIS) and autofocusing (AF) camera modules, power efficiency and size are two of the most important characteristics. Therefore, in this paper, we propose a novel voice coil motor (VCM) OIS/AF camera module for cellphones to satisfy the requirements of small size and high power efficiency. The design optimization of the proposed VCM OIS/AF camera module is done using simulations. The results of the simulations show that the proposed VCM OIS camera module has excellent characteristics when compared to a conventional VCM OIS camera module. [ABSTRACT FROM AUTHOR]

The smart cell phone market has rapid growth in recent years and cell phone camera modules have strong requirement for capturing images and communication in our daily use. Accordingly, in the present study, a novel compact voice coil motor (VCM) actuator is proposed for auto-focusing (AF) of cell phone camera modules. Compared to conventional VCM actuators with open-loop position control mechanism, the proposed VCM actuator is featured with absence of spring plates. In the proposed approach, the magnetic restoring force is used to replace the restoring force of the spring plates in the open-loop control VCM actuators. The motivation of this study is to characterize the performance of the proposed VCM actuator using simulation methods and then evaluate experimentally this device using a laboratory-built prototype. The results show that the proposed VCM actuator has the sizes of 8.5 mm × 8.5 mm × 7.5 mm, the maximal input current of 40 mA, the maximal response time of 10 ms, and the average measured Lorentz force of 2200 mgw for the input current of 40 mA in its whole displacement (stroke of 0.4 mm), and it operates the AF function well. [ABSTRACT FROM AUTHOR]

The phonon-replica infrared emission is observed at room temperature from indirect band gap Si light-emitting diode under forward bias. With increasing injection current density, the broadened electroluminescence spectrum and band gap reduction are observed due to joule heating. The spectral-resolved temporal response of electroluminescence reveals the competitiveness between single (TO) and dual (TO+TA) phonon-assisted indirect band gap transitions. As compared to infrared emission with TO phonon-replica, the retarder of radiative recombination at long wavelength region (~1.2 lm) indicates lower transition probability of dual phonon-replica before thermal equivalent. [ABSTRACT FROM AUTHOR]

Physiological changes in the retinal vasculature are commonly indicative of such disorders as diabetic retinopathy, glaucoma, and age-related macular degeneration. Thus, various methods have been developed for noninvasive clinical evaluation of ocular hemodynamics. However, to the best of our knowledge, current ophthalmic instruments do not provide a true color blood flow imaging capability. Accordingly, we propose a new method for the true color imaging of blood flow using a high-speed pulsed laser photography system. In the proposed approach, monochromatic images of the blood flow are acquired using a system of three cameras and three color lasers (red, green, and blue). A high-quality true color image of the blood flow is obtained by assembling the monochromatic images by means of image realignment and color calibration processes. The effectiveness of the proposed approach is demonstrated by imaging the flow of mouse blood within a microfluidic channel device. The experimental results confirm the proposed system provides a high-quality true color blood flow imaging capability, and therefore has potential for noninvasive clinical evaluation of ocular hemodynamics. [ABSTRACT FROM AUTHOR]

Abstract  This paper presents the design and fabrication of a miniature axial-gap spindle motor for small-form-factor optical storage applications. The motor features a fluid dynamic bearing (FDB) and is characterized by a high mechanical rigidity, excellent dynamic characteristics, and a zero cogging torque. The performance of this FDB motor is evaluated experimentally using a laboratory-built prototype. The results show that the motor has an excellent dynamic response, a small axial repeatable runout, a small tilt angle, a high rotational speed, and a low operating current. Furthermore, with overall dimensions of just 15.5 × 3.3 mm, the FDB motor is around 80% smaller than that presented by the current group in a previous study (Liu et al., J Magn Magn Mater 304:362–364, 2006). Consequently, the proposed motor represents an ideal solution for both existing and emerging miniaturized portable storage device applications. [ABSTRACT FROM AUTHOR]

The measuring accuracy of conventional laser displacement sensors reduces over time as a result of geometrical fluctuations of the laser beam. Accordingly, the present study proposes a new laser displacement sensor in which the effects of geometrical fluctuations of the laser beam are minimized by means of a high-speed rotating optical diffuser. The performance of the proposed sensor is evaluated experimentally using a laboratory-built prototype. The experimental results show that the sensor achieves a higher measuring accuracy than a conventional laser displacement sensor based on a triangulation method. As a result, the proposed sensor provides an ideal solution for a wide range of automatic optical inspection and industrial applications. [ABSTRACT FROM AUTHOR]

This paper presents the development of a miniature axial-field spindle motor. Such a spindle motor could play a very important role in modern storage devices, which demand increasingly large storage capacity under limited physical space, especially for the miniature hard-disk drive or small-form-factor optical (SFFO) storage drive developments. In the present paper, an axial-field motor structure was employed to facilitate the design of a miniature spindle motor of a low profile height. In addition, the axial spoolless coil windings, which eliminate the cogging torque due to slot, serve as the electromagnetic exciting source. [ABSTRACT FROM AUTHOR]

When designing an auto-focusing actuator for use in cell phone cameras, it is essential to minimize the device size, maximize the positioning repeatability, and minimize the power consumption. In a previous study, we presented a miniature auto-focusing voice coil motor (VCM) actuator for cell phone camera applications in which the lens was precisely positioned by a closed-loop feedback signal generated by a Hall element. Our study characterizes the performance of this device by using an experimental approach. The results show that the proposed actuator is not only smaller than a conventional VCM actuator with an open-loop positioning system, but also has improved positioning repeatability, a more rapid response, and lower power consumption. [ABSTRACT FROM AUTHOR]

This paper presents a synchronous measurement methodology aimed at identifying four position-independent geometric errors (PIGEs) and six position-dependent geometric errors (PDGEs) of the rotary axis in five-axis machine tools. Previous studies and literature have emphasized the challenge of simultaneously measuring and identifying PIGEs and PDGEs of the rotary axis in five-axis machine tools. Therefore, the primary objective of this paper is to propose a measurement methodology that can identify these errors simultaneously through a single measuring process. Compared to commercially available measuring instruments, this measurement system offers several advantages: it is easy to install, cost-effective, and can be applied to various types of five-axis machine tools. These benefits enable the establishment of a fast on-machine error measurement. The initial phase of the research involves establishing a mathematical model and computing the geometric error equations based on the specific type of machine tools in use. Subsequently, the difference between the ideal and actual center positions of the calibration sphere is determined by utilizing a touch-trigger probe while positioning the machine's rotary table at various angles. Finally, the experimental data is inputted into the mathematical algorithm to obtain the PIGEs and PDGEs of the rotary table. Post-experimentation, the PIGEs and PDGEs obtained through the proposed measurement method are incorporated into the controller as compensations. The feasibility of this approach is evaluated by measuring the volumetric errors of the machine tools both with and without compensation. The results demonstrate a significant reduction in the deviation of the volumetric errors, decreasing from 11.97 to 2.31 µm after compensation. This outcome underscores the potential of the proposed method for simultaneous measurement of geometric errors in the rotary axis of machine tools across various types and scenarios. Highlights: This paper proposes a novelly synchronous measurement methodology for identifying the four position-independent geometric errors (PIGEs) and six position-dependent geometric errors (PDGEs) of the rotary axis in five-axis machine tools. The measurement principle, geometric errors calculation algorithm as well as simulation and experiment verification of the proposed synchronous measurement methodology are presented. Based on experimental results demonstrating a reduction in volumetric error of up to 80.7%, it is evident that the proposed measurement method is both efficient and precise. [ABSTRACT FROM AUTHOR]

This paper presents the effects of the fluid dynamic bearing (FDB) design on the rotational precision of a spindle motor used for drivers requiring higher recording density and data transfer rate. Adopting the numerical flow field analysis on the FDB, the developed motor has robust operating stability in an operational window. The FDB provides the optimal load capacity demonstrated by the experimental results. In addition, the developed motor has excellent axial repeatable run-out performance less than 4 μm. [ABSTRACT FROM AUTHOR]

For achieving high precision and effectiveness in five-axis computer numerical control (CNC) machine tools, the geometrical accuracy of the rotary axes is a crucial performance criterion. Furthermore, recent advancements in commercial CNCs for machine tools have enabled the numerical compensation for all parameters of geometric errors within rotary axes. As a result, this paper initially delves into the evolution of ISO standards concerning the accuracy testing and error definition in machine tools. Subsequently, the classifications of the rotary axis's geometric errors in five-axis machine tools are described in this paper. Moreover, this paper comprehensively reviews various measurement schemes aimed at identifying the geometric errors of rotary axes. These measurement schemes are categorized based on the measurement instruments or technologies employed. Finally, it is essential to emphasize that this paper offers an overview of diverse measurement theories and technologies pertaining to geometric errors in rotary axes. The primary aim is to contribute to the progression of geometric error measurement and compensation in five-axis machine tools. [ABSTRACT FROM AUTHOR]

Optical scanners play a key role in many three-dimensional (3D) printing and CAD/CAM applications. However, existing optical scanners are generally designed to provide either a wide scanning area or a high 3D reconstruction accuracy from a lens with a fixed focal length. In the former case, the scanning area is increased at the expense of the reconstruction accuracy, while in the latter case, the reconstruction performance is improved at the expense of a more limited scanning range. In other words, existing optical scanners compromise between the scanning area and the reconstruction accuracy. Accordingly, the present study proposes a new scanning system including a zoom-lens unit, which combines both a wide scanning area and a high 3D reconstruction accuracy. In the proposed approach, the object is scanned initially under a suitable low-magnification setting for the object size (setting 1), resulting in a wide scanning area but a poor reconstruction resolution in complicated regions of the object. The complicated regions of the object are then rescanned under a high-magnification setting (setting 2) in order to improve the accuracy of the original reconstruction results. Finally, the models reconstructed after each scanning pass are combined to obtain the final reconstructed 3D shape of the object. The feasibility of the proposed method is demonstrated experimentally using a laboratory-built prototype. It is shown that the scanner has a high reconstruction accuracy over a large scanning area. In other words, the proposed optical scanner has significant potential for 3D engineering applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Fishery is vital for Taiwan's economy, and over 40% of the fishery products come from aquaculture. Traditional aquaculture relies on the visual observation of a water-wheel tail length to assess water quality. However, the aging population, lack of young labor, and difficulty in passing down experience pose challenges. There is currently no systematic method to determine the correlation between the water quality and water-wheel tail length, and adjustments are made based on visual inspection, relying heavily on experience without substantial data for transmission. To address the challenge, a precise and efficient water quality control system is proposed. This study proposes a water-wheel tail length measurement system that corrects input images through image projective transformation to obtain the transformed coordinates. By utilizing known conditions of the water-wheel, such as the length of the base, the actual water-wheel tail length is deduced based on proportional relationships. Validated with two different calibration boards, the projective transformation performance of specification A is found to be better, with an average error percentage of less than 0.25%. Data augmentation techniques are employed to increase the quantity and diversity of the dataset, and the YOLO v8 deep learning model is trained to recognize water-wheel tail features. The model achieves a maximum mAP50 value of 0.99013 and a maximum mAP50-95 value of 0.885. The experimental results show that the proposed water-wheel tail length measurement system can be used feasibly to measure water-wheel tail length in fish farms. [ABSTRACT FROM AUTHOR]

I Machines i was able to uphold its high standards for published papers due to the outstanding efforts of our reviewers. [Extracted from the article]

Regardless of whether the articles they examined were ultimately published, the editors would like to express their appreciation and thank the following reviewers for the time and dedication that they have shown I Sensors i :ely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). Thanks to the efforts of our reviewers in 2022, the median time to first decision was 16 days and the median time to publication was 38 days. I Sensors i was able to uphold its high standards for published papers due to the outstanding efforts of our reviewers. [Extracted from the article]

Regardless of whether the articles they examined were ultimately published, the editors would like to express their appreciation and thank the following reviewers for the time and dedication that they have shown I Applied Sciences i : se of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). I Applied Sciences i was able to uphold its high standards for published papers due to the outstanding efforts of our reviewers. [Extracted from the article]

Thanks to the efforts of our reviewers in 2022, the median time to first decision was 15 days and the median time to publication was 36 days. I Electronics i was able to uphold its high standards for published papers due to the outstanding efforts of our reviewers. Regardless of whether the articles they examined were ultimately published, the editors would like to express their appreciation and thank the following reviewers for the time and dedication that they have shown I Electronics i :e of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). [Extracted from the article]

The force measurement is essential in many engineering areas and our life. Accordingly, this paper proposes a new force sensor, in which the restoring force of the traditional spring is replaced by an axial magnetic attraction force. The performance of the proposed force sensor is characterized numerically by means of MagNet simulations and is then verified experimentally using a laboratory-built prototype. The experimental results show that a linear relation exists between the axial magnetic attraction force and the displacement of the moving part. It also confirms that the proposed force sensor can successfully measure the applied force via the output of the displacement. Due to such characteristics, the potential applications of the proposed force sensor are in the field of autofocusing voice coil motor actuators for cell phone camera modules. [ABSTRACT FROM PUBLISHER]

The grinding force is the most sensitive physical measure of reaction loads in the grinding process. To enhance surface quality and assure high efficiency and stability of the grinding process, it is essential to accomplish adaptive control of the grinding force. This paper suggests a grinding force adaptive control system based on spindle motor power feedback, considering the process–machine interaction. The spindle motor power is utilized as a proxy for the grinding force because of the mapping relationship between the two variables. The machine tool's feed rate is automatically modified to achieve adaptive control of the grinding force, after assessing the discrepancy between the collected spindle motor power and the preset power. Finally, a cemented carbide tool grinding experiment was performed on a 2MZK7150 CNC tool grinder. During the experiment, the grinding force was precisely controlled between 80 and 100 N, ensuring machining quality and increasing machining efficiency. The experimental results show that the adaptive control system can meet the high-efficiency and high-quality machining requirements of cemented carbide rotary blades. [ABSTRACT FROM AUTHOR]

With the aim of enhancing the machining accuracy of the horizontal boring and milling machine tool, this study proposes an on-machine measurement methodology for identification and compensation of geometric errors of the facing head by using a touch-trigger probe and a precise sphere. Based on the past machining experiences provided by the machine supplier, the geometric errors of the facing head lead to the serious problem: the inner and outer holes of the workpieces are not concentric during the boring process. This problem causes the poor machining accuracy of the workpieces. As a result, in this study, a robust algorithm for calibrating the four geometric errors of the facing head is proposed by establishing the mathematical measurement equations. Furthermore, the mathematical measurement equations are mainly built by applying forward and inverse kinematic approach as well as the least square method. Finally, the measurement and machining verifications are also performed for demonstrating the feasibility and accuracy of the proposed measurement method. The experimental measurement results show that the position errors and the orientation errors are at most about − 76.3 μm and − 37.6 arcsec, respectively. On the other hand, after identifying the four geometric errors of the facing head, they are compensated to the controller. Consequently, the machining verification results show that the concentricity of inner and outer holes of the boring workpiece with compensation is significantly reduced to 0.024 mm from 0.179 mm. Conclusively, the efficiency and effectiveness of the proposed measurement method have been demonstrated. [ABSTRACT FROM AUTHOR]

This paper proposes a synchronous measurement system of four position-independent geometric errors (PIGEs) and two position-dependent geometric errors (PDGEs) for the rotary axis in five-axis machine tools. The measuring instruments used in this system include a touch-trigger probe and two standard calibration spheres. The main contribution of this paper simultaneously and directly measures four PIGEs and two PDGEs (axial and angular positioning errors) through only one measuring process. It is expected to improve the deficiencies of previous studies measuring PIGEs and PDGEs separately. The geometric errors of the C-axis of a mill-turn machine tool MT-540 were analyzed. The calculation process includes the establishment of the mathematical model of the machine and geometric error equations. The least squares method was used to solve the linear overdetermined system and calculate the values of the geometric errors. Before solving the geometric errors, the accuracy of the calculation process was verified by using the simulated method. The simulation results also confirm the feasibility of this measurement system. Then the data obtained from the experiments were used to calculate the geometric errors of the machine tool. During the experiments, the calibration procedure of the touch-trigger probe was calibrated. After the calibration procedure was completed, the mechanical coordinate values of the two standard calibration balls were measured. The geometric error equations were programmed on a computer, and the data of calibration spheres obtained from the experimental measurements were substituted into the program to calculate the four PIGEs and two PDGEs. [ABSTRACT FROM AUTHOR]

For automated optical inspection, autofocusing microscopes play an important role in capturing clear images of the measured object. At present, the image processing part of optics-based autofocusing microscopes often has various factors, which makes it impossible to describe the image information of the semicircular (or elliptical) spot with a simple circle-finding method. Accordingly, this study has developed a novel algorithm that can quickly calculate the ideal center of the elliptical spot and effectively compensate the linearity of the focusing characteristic curve. A prototype model was used to characterize and verify the proposed algorithm. The experimental results show that by using the proposed algorithm, the autofocusing accuracy can be effectively improved to less than 1.5 μm. [ABSTRACT FROM AUTHOR]

Commercial laser interferometers are conventionally used to measure the positioning error of a long linear stage in multiaxis computer numerical control machine tools. However, commercial laser interferometers are costly and difficult to use. Therefore, a low-cost photodetector-based heterodyne interferometer combined with an electronic phasemeter module was proposed for precise measurement of the positioning error of a long linear stage. The proposed heterodyne interferometer was combined with a virtual electronic phasemeter that employs a self-developed signal-processing technique. Our core algorithm and proposed photoelectric-signal-processing technique were developed using the LabVIEW human–machine interface. Moreover, to verify the performance of the proposed heterodyne interferometer, a laboratory-built prototype was constructed and used to measure the positioning error of a long linear stage. The experimental results indicated that the positioning accuracy of the proposed interferometer was ±4.5 μm for a linear stage with a displacement of 250 mm; the results obtained were comparable to those obtained with a commercially available laser interferometer. The proposed heterodyne interferometer can thus be used in other applications related to precision engineering. [ABSTRACT FROM AUTHOR]