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In order to simultaneously obtain the thickness and refractive index for each layer of multilayered samples, this paper proposes a novel measurement system with a simple structure by using geometric optics. The key point of the overall structure is that the binary linear equation relation between the upper and lower planes of the layer can be known by the distances between laser spots reflected from the layer. Using two optical paths with different incident angles of laser beams, the CCD sensors capture the spot signal for image processing binarization and data sampling. After the obtained laser spots' spacing is substituted into the equations, the thicknesses and refractive indexes of the multilayered samples can be calculated and measured. The proposed measurement system is characterized numerically using simulations on the commercial software program Zemax and then experimentally tested using a laboratory-built prototype. The experiment results show that the refractive indexes and the thicknesses of three-layer samples were measured with high accuracy (with maximum measurement errors of 2.4% and 2% for a refractive index n and thickness t, respectively).

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 4-degree-of-freedom (DOF) actuator for a fast steer mirror (FSM) compensation system in order to compensate for 4-DOF laser errors. The mathematic system modeling was built to design and predict the performance of the proposed 4-DOF FSM. Finite element analysis was performed by using a commercial software to analyze the characteristics of the electromagnetic structure and mechanical structure for the proposed 4-DOF FSM. This study further verifies the properties of the proposed 4-DOF FSM by using a laboratory-built prototype. The proposed 4-DOF FSM has the travel range of ±5 mrad and ±0.04 mm along X and Y axes with accuracy of 0.025 mrad and 0.0012 mm and the bandwidth of rotational part and translational part are 10 Hz and 39 Hz, respectively.

In the manufacturing industry, grinding is used as a major process for machining difficult-to-cut materials. Grinding is the most complicated and precise machining process. For grinding machines, continuous generating gear grinding machines are widely used to machine gears which are essential machine elements. However, due to its complicated process, it is very difficult to design a reliable measurement method to identify the grinding wheel loading phenomena during the grinding process. Therefore, this paper proposes a measurement method to identify the grinding wheel loading phenomenon in the grinding process for continuous generating gear grinding machines. In the proposed approach, an acoustic emission (AE) sensor was embedded to monitor the grinding wheel conditions, an offline digital image processing technique was used to determine the loading areas over the surface of Al2O3 grinding wheels, and surface roughness of the ground workpiece was measured to quantify its machining quality. Then these three data were analyzed to find their correlation. The experimental results have shown that there are two stages of grinding in the grinding process and the proposed measurement method can provide a quantitative grinding wheel loading evaluation from the AE signals online.

The function of optical zooming is really rare in smartphone cameras due to its appearances and dimensions now. The manufactures need to provide a better optical performance and make a new gimmick to attract consumers. As a result, a novel VCM actuator with optical zoom for smartphone cameras is proposed in this paper, it has a simpler structure when compared to stepping motor smartphone cameras. The paper presents a segmented magnetic equivalent circuit method to analyze the magnetic characteristics of proposed VCM actuator and further verified by a commercial finite element model software. Furthermore, the performance of the proposed optical zoom VCM actuator was verified by constructing a laboratory-built prototype, the experimental results shows that the proposed VCM actuator has good positioning accuracy and good dynamic response.

Measuring the refractive index and thickness of transparent materials is essential in offline or online automated inspection in the manufacturing and industrial fields. We recently developed a novel optical system with two optical paths for simultaneously measuring the refractive index and thickness (>1 mm) of a transparent plate; the developed system allowed for better thickness measurement with a simpler structure and lower cost (C. S. Liu, R. C. Song, and S. J. Fu, Appl. Phys. B 125, 199, 2019). In the present study, the thickness range that can be measured using the developed optical system is reduced to ≤100 μm by using interference methods instead of triangulation methods. The proposed optical interference system is characterized numerically using simulations on the commercial software program ZEMAX and then experimentally tested using a laboratory-built prototype. The experiment results show that the refractive indexes and the thicknesses of the slim transparent plates (thickness ≤ 100 μm) were measured with high accuracy (with maximum measurement errors of 0.0007 and 3 μm for a refractive index n and thickness d, respectively). Consequently, the proposed optical interference system has the potential to be used in the automated inspection of slim transparent materials.

In order to deal with the free boundary problems occurred in cavitation region, this work incorporates an artificial term in Reynolds equation to stabilize the solution. The current result shows that adding the extra term gives accurate pressure distribution and benefits the selection of the groove shape and size. In addition, this study utilizes herringbone grooves on a reversible rotating journal bearing (RHGJB) and numerically analyzes the characteristics of miniature journal bearings with an inner diameter of 0.6 mm. Miniature journal bearings are limited in that the load capacity is significantly reduced with decreased bearing size, and therefore, the performances (load capacity and side leakage) of miniature RHGJBs are optimized. The optimum geometrical appearance of miniature RHGJBs is calculated by evaluating several groove parameters. Using the Taguchi parameter design methodology greatly reduces the number of full-factorial experimental design tests required to determine the optimal design parameters of the RHGJB from 59 (1,953,125) to 450 runs.

The autofocusing (AF) performance of cell phone cameras is critically dependent on the design of the voice-coil motor (VCM) used to drive the lens module. Also, the metal springs in the AF module should combine high stiffness with a good actuation response and a light weight. The present study utilizes a reverse engineering approach to construct three-dimensional finite element models of the top and bottom springs in the VCM mechanism. Simulations are then performed to investigate the von Mises stress distribution and stiffness characteristics of the two springs given horizontal and vertical orientations of the AF module, respectively. In performing the simulations, the actuation force is computed using two different analysis methods, namely a simplify structure method and a coupled electromagnetic-structural method. It is shown that the simplify structure method has the advantages of a lower computational complexity and a more comprehensive modeling capability. A further series of simulations is thus to examine the effects of the spring shape parameters on the reaction force developed by the spring stiffness. The results show that the spring stiffness increases with an increasing thickness and a decreasing rib length. The simulation results obtained for different spring shape parameter settings are summarized in the form of a parameter design chart for predicting the reaction force given known values of the spring rib length and spring thickness.

In this study, a novel and simple measurement system for simultaneously measuring the geometric errors in six-degree-of-freedom (6-DOF) for a moving linear stage of a machine tool is designed and validated. Compared to laser interferometer and laser Doppler systems, this new measurement system is less expensive and capable of multiple functions. The proposed measurement system comprises an optics module, composed of two reflectors and two cubic beam splitters; a sensing module, composed of three two-dimensional position sensitive detectors (PSDs); and a helium-neon (He-Ne) laser. Using skew-ray tracing and a first-order Taylor series expansion, the 6-DOF geometric errors of the moving linear stage, which include translation and rotation errors, are analyzed. A laboratory prototype system is built to verify the effectiveness and accuracy of the proposed measurement system. The experimental results show that the displacement uncertainty and the angular uncertainty of the proposed measurement system are less than 1.2 µm and 0.4″, respectively. Compared with the Renishaw laser interferometer XL-80 laser system, the translational accuracy and the rotational accuracy of the proposed measurement system are less than ±1 µm and ±0.2″, respectively, when the linear stage travels 6 mm.

Recently, consumers pay close attention to the function of smartphone cameras. The prevalence of smartphone cameras with the high pixels lens causes users to be not satisfied with only the auto-focusing function. The smartphone cameras specifically require the optical image stabilization (OIS) function helping users get sharper and clearer images. Therefore, this paper presents a voice coil type OIS actuator for smartphone cameras with novel electromagnetic design that features the magnets with chamfered edge to reduce the size and the cost of the OIS actuator and improve its power efficiency. And this paper proves its performance through the laboratory-built prototype. The experimental results show that the proposed OIS actuator with the novel electromagnetic design can supply greater and more stable Lorentz force when comparing with the commercial OIS product and the performance of the proposed novel design is robust.

In recent years, compact camera modules (CCMs) have been widely used in consumer electrical and electronic products. CCMs with low cost specially are necessary for portable devices. Therefore, the present group recently developed a miniaturized open-loop controlled camera module with low cost for cellphone applications, in which the Lorentz force is balanced by a magnetic restoring force. To enhance the performance of the camera module, this article reports a pattern structure to modify the linearity of the magnetic restoring force. We fabricated a CCM prototype with the dimensions of 8.5 mm × 8.5 mm × 5 mm and demonstrated the usefulness of the pattern structure with the CCM prototype. Its potential applications are foreseeable in portable devices, such as cellphones, web cameras, personal digital assistants and other commercial electronics.

This study proposes a new type of autofocusing microscope. The microscope was combined with a polarized beam-splitting system and an image-processing program to overcome the complex signals generated when focusing on a transparent boundary layer. The polarized beam-splitting system divides a source laser beam into four parallel beams using a birefringent crystal. It also uses an axicon lens to focus individually on different positions of the sample surface when light is incident on the objective lens to observe multiple-spot defocusing information simultaneously. The transparent boundary layer exhibits intricate signals when a sensor detects laser spots. Therefore, an image-processing program is proposed to filter unnecessary signals for calculating the evaluation function and driving the motor, which enables a focused view of the test sample to be attained conveniently. To prove the feasibility of the proposed autofocusing microscope, a frame was developed using a simulation software for observing the initial characteristics of the microscope and for conducting a qualitative analysis. Moreover, the image-processing effect on the sample was tested to determine whether the aim of the study was achieved. The experimental results matched suitably with the simulation results, which indicates that the proposed autofocusing microscope can solve the problem caused by the transparent boundary layer and can achieve a high focusing accuracy within a short focusing time.

Consumers pay most attention to the camera function of smartphones. Thus, manufacturers focus on improving the capabilities of camera modules to deliver clearer and sharper images to consumers. Today, camera modules with auto focusing (AF) and optical image stabilization (OIS) functions are standard in the industry. Specifically, OIS is of the linear movement and rotational movement types. In contrast to the rotational movement type, the commonly used linear movement type cannot compensate for rotational error. Therefore, this paper proposes a novel voice coil motor (VCM) actuator that can supply a 5 degree of freedom (DOF)–compensation that consists of three linear movements and two rotational movements for smartphone camera modules. This novel VCM actuator with 5-DOF compensation is realized using an innovative electromagnetic structure. This paper further verifies the properties of the proposed VCM actuator with a laboratory-built prototype. The experimental results verify the robust properties and feasibility of the proposed VCM actuator.

This paper describes the implementation and optimization of a dual-confocal autofocusing system that can easily describe a real-time position by measuring the response signal (i.e., intensity) of the front and the rear focal points of the system. This is a new and systematic design strategy that would make it possible to use this system for other applications while retrieving their characteristic curves experimentally; there is even a good chance of this technique becoming the gold standard for optimizing these dual-confocal configurations. We adopt two indexes to predict our system performance and discover that the rear focal position and its physical design are major factors. A laboratory-built prototype was constructed and demonstrated to ensure that its optimization was valid. The experimental results showed that a total optical difference from 150 to 400 mm significantly affected the effective volume of our designed autofocusing system. The results also showed that the sensitivity of the dual-confocal autofocusing system is affected more by the position of the rear focal point than the position of the front focal point. The final optimizing setup indicated that the rear focal length and the front focal length should be set at 200 and 100 mm, respectively. In addition, the characteristic curve between the focus error signal and its position could successfully define the exact position by a polynomial equation of the sixth order, meaning that the system can be straightforwardly applied to an accurate micro-optical auto-focusing system.

This paper proposes a new kind of non-contact optical measurement system, which combines with a polygon mirror and a conical lens to achieve the purpose of simultaneously measuring six-degree-of-freedom (6 DOF) geometric errors for a rotary axis of a machine tool. At the beginning, we used the Zemax software to construct the proposed optical structure and observe the change of light spots on the detectors. Then, we built the proposed optical structure on the Matlab software by using the skew-ray tracing method, which used to present the actual condition of light spot change and compare with the simulation results. Then, we designed the appropriate fixtures to place the system structure on a rotary axis in a laboratory environment. After completing the laboratory-built prototype, we analyzed the effects of different geometric errors on the detectors at different angular positions of a rotary axis of a machine tool. The proposed measurement system simultaneously measured 6 DOF geometric errors of the rotary axis, and the experimental results were compared with those of two dial gauges by using the measurement method of ISO 230–7. The experimental results show that the maximum deviation ranges of the radial motion error in X axis, the radial motion error in Y axis, the tilt motion error around X, and the tilt motion error around Y are ±4.7 µm, ±6.0 µm, ±3.6 arcsec, and ±8.1 arcsec, respectively.

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&rsquo, 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&rsquo, s skew ray tracing method was used to perform mathematical modeling and ray matching. Each error&rsquo, 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&rsquo, 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 &plusmn, 0.5 arcsec, &plusmn, 3.6 arcsec, &plusmn, 2.1 &mu, m, and &plusmn, 2.3 &mu, m, respectively. The maximum repeatability deviations for the measured guide&rsquo, s pitch, yaw, roll, horizontal straightness, vertical straightness, and positioning errors are 0.4 arcsec, 0.2 arcsec, 4.2 arcsec, 1.5 &mu, m, 0.3 &mu, m, and 3 &mu, m, respectively.

This study proposes a novel FSM compensation system for four degrees of freedom (DOF) laser errors compensation, which has the advantage of shorter optical path length, fewer elements and an easier set-up process, meaning that it can be used at different locations. A commercial software, Zemax, is used to evaluate the function of the proposed FSM compensation system and the mathematical modelling of the proposed FSM compensation system is established by using a skew-ray tracing method. Finally, the proposed FSM compensation system is then verified experimentally using a laboratory-built prototype and the result shows that the proposed FSM compensation system achieves the ability to compensate the 4 DOF of the laser source.

This study designs and characterizes a novel optical system for simultaneously measuring the thickness (> 1 mm) and refractive index of a transparent plate with two optical paths. The proposed optical system is based on triangulation methods. In contrast to exiting optical system based on triangulation methods for simultaneous measurements of thickness and refractive index of a transparent plate, the proposed optical system can measure a greater thickness with a simpler structure and lower cost. The two optical paths are combined using a self-written measurement processing algorithm to simultaneously calculate the thickness and refractive index. The principle and measurement methodology of the proposed optical system are analyzed and explained. The performance of the proposed optical system is then verified and evaluated experimentally using a laboratory-built prototype. The experimental results show that the measured thicknesses and refractive indexes for Sample B (the thickness > 1 mm) are in good agreement with those determined by a commercial instrument with the maximum deviation of 0.019% for the thickness d and 0.007% for the refractive index n, respectively.

Recently, compact and high-resolution camera modules with auto-focusing (AF) function have been integrated into cell phones in order to capture sharp photographs. Consumer demands AF camera modules in cell phones to have high performance with low cost. Accordingly, the present study proposes a new electromagnetic design of miniature AF voice coil motor (VCM) actuator with closed-loop control for cell phone camera modules to satisfy the requirements. The structure of the proposed AF VCM actuators was designed by using simulation methods. The performance of the proposed AF VCM actuators was demonstrated by a laboratory-built prototype. The experimental results have shown that the proposed AF VCM actuator has excellent performance with lower power consumption, higher positioning repeatability, and lower cost, when compared to previous AF VCM actuators with open-loop control or closed-loop control.

For miniature spindle motors design and their applications, the output torque is one of the most important characteristics and it is necessary to improve the output torque of miniature spindle motors in keeping with consumer preferences. Accordingly, this paper is aimed to overcome this problem and propose a novel electromagnetic structure design to improve the output torque of the spindle motor for miniature cooling fans and modern consumer electronic products. In contrast to one phase DC brushless motor with only one axial air gap or radial air gap inside its electromagnetic structure, the proposed one phase DC brushless motor comprises simultaneously one axial air gap and radial air gap inside its electromagnetic structure. This paper utilizes commercial software MagNet to numerically verify the proposed one phase DC brushless motor. The simulation results show that compared to the conventional one phase DC brushless motors with only one axial air gap or radial air gap, the proposed one phase DC brushless motor can improve the output torque obviously. In other words, the novel electromagnetic structure of the proposed one phase DC brushless motor can enhance the operation efficiency. As a result, the results presented in this study show that the proposed one phase DC brushless motor provides potential solution for both existing and emerging miniature spindle motor applications.

In this paper, the calibration method of multi-focal planes of a 3D scanning system with zoom-lens unit based on structured light has been discussed. Based on the development of calibration methods for zoom lens characteristics, we design a calibration target for zoom lens calibration. Also, we present a pragmatic calibration process that consists of five procedures.

This study designs and characterizes a novel precise measurement system for simultaneously measuring six-degree-of-freedom geometric motion errors of a long linear stage of a machine tool. The proposed measurement system is based on a method combined with the geometrical optics method and laser interferometer method. In contrast to conventional laser interferometers using only the interferometer method, the proposed measurement system can simultaneously measure six-degree-of-freedom geometric motion errors of a long linear stage with lower cost and faster operational time. The proposed measurement system is characterized numerically using commercial software ZEMAX and mathematical modeling established by using a skew-ray tracing method, a homogeneous transformation matrix, and a first-order Taylor series expansion. The proposed measurement system is then verified experimentally using a laboratory-built prototype. The experimental results show that, compared to conventional laser interferometers, the proposed measurement system better achieves the ability to simultaneously measure six-degree-of-freedom geometric errors of a long linear stage (a traveling range of 250 mm).

We recently developed a novel force sensor in which the restoring force of the traditional spring is replaced by an axial magnetic attraction force. In this letter, the linearity of the axial magnetic attraction force–displacement curve is further improved via the addition of two yokes. The performance of the proposed force sensor is numerically characterized by means of simulations and then verified experimentally using a prototype. The results show that the proposed force sensor has a higher linearity of the axial magnetic attraction force–displacement curve (improvement around 1.53%). Moreover, a novel cell phone camera module using the proposed structure is demonstrated with a fast response (≤9 ms) and an improved power efficiency (≤11 mA).

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.

Automated optical inspection is a very important technique. For this reason, this study proposes an optical non-contact slanting surface measuring system. The essential features of the measurement system are obtained through simulations using the optical design software Zemax. The actual propagation of laser beams within the measurement system is traced by using a homogeneous transformation matrix (HTM), the skew-ray tracing method, and a first-order Taylor series expansion. Additionally, a complete mathematical model that describes the variations in light spots on photoelectric sensors and the corresponding changes in the sample orientation and distance was established. Finally, a laboratory prototype system was constructed on an optical bench to verify experimentally the proposed system. This measurement system can simultaneously detect the slanting angles (x, z) in the x and z directions of the sample and the distance (y) between the biconvex lens and the flat sample surface.