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High-speed Permanent Magnet Linear Synchronous Motor (PMLSM) is desired by high performance electromagnetic propulsion system. A novel frequency modulation (FM) secondary proposed here to overcome the issues resulting from a big pole pitch of high-speed PMLSM, as well as avoid a damage to the thrust characteristics. Firstly, the topology structure of FM secondary is designed, modeling of the main magnetic field excited by permanent magnets (PMs) is accomplished. And the impacts of FM secondary on the main magnetic field and PM eddy-current loss are presented based on the analytical method and finite element method (FEM). The electromagnetic thrust of PMLSM with FM secondary is calculated, and the influences of FM secondary on thrust characteristics are studied by FEM simulations. Finally, a prototype of PMLSM with FM secondary is manufactured, the experiments are provided to validate the analytical results and simulation results of FM secondary.

High speed linear motor with low thrust ripple is one of the research focuses of high performance systems. This paper proposes a novel secondary topology for Permanent Magnet Linear Synchronous Motor (PMLSM) with high speed, to suppress the thrust ripple. Permanent magnet (PM) width modulation secondary adopts several PMs to excite the main magnetic field per pole. The issues from a big pole pitch which is generally used by high-speed PMLSM, are solved. These PMs have various longitudinal lengths based on the pulse width modulation principle, to achieve a magnetic field with excellent sinusoidal features. First, the topology structure of PM width modulation secondary is designed. The analytical model of the main magnetic field excited by PMs in this novel secondary is established, the electromagnetic thrust is calculated. Furthermore, the influences of PM width modulation secondary on the main magnetic field and thrust properties are analyzed. The comparisons between two PMLSMs employing PM width modulation secondary and Halbach secondary respectively, are provided. Finally, prototypes are manufactured and tested, to verify the effectiveness of the topology proposed in this research.

Optoelectronic packaging is an important component of optical communication systems. However, it is a challenge for the packaging equipment to simultaneously have multiple degrees of freedom (DOF), wide range, and high precision. In this article, a six-degree-of-freedom (6-DOF) compliant parallel platform with all these features is presented. This platform has a parallel basic structure with large-stroke flexible joints. Based on elastokinematic analysis, the inverse kinematics solution of the platform is derived, and the effectiveness of the platform is proved by analyzing the 6-DOF motion via finite element analysis. The reachable workspace of the platform is analyzed, and its solution process is simplified using the inverse distance weighted method. Furthermore, a prototype of the proposed platform is presented and its accuracy is evaluated through experiments. Error compensation is used to significantly improve the motion accuracy of the platform. A closed-loop control that uses optical power meters instead of a multi-DOF detection device is proposed for optoelectronic packaging. The performance of the prototype applied to the packaging of coaxial optoelectronic devices is also demonstrated by experiments. The results demonstrate that the 6-DOF compliant parallel platform can successfully carry out the optical alignment of optoelectronic devices.

With the development of high performance processing system, high precision Permanent Magnet Linear Synchronous Motor (PMLSM) has been the focus of research. This paper provides a novel double-sided PMLSM with quasi- sinusoidal ring windings, to reduce the thrust ripple while keep the average thrust at a suitable value. Firstly, the distributions of the magnetic fields in this motor are analyzed, the low-order harmonics of armature magnetic field induced by the quasi- sinusoidal ring windings are studied, by equivalent magnetizing current (EMC) method. The winding factor and the Back Electromagnetic Force of this PMLSM are analyzed theoretically and verified by finite-element (FEM) method, based on the specific structure of quasi-sinusoidal ring windings. Furthermore, the electromagnetic thrust analysis is provided, which is aimed at the influence of the novel winding structure. Finally, a prototype of the double-sided PMLSM with quasi-sinusoidal ring windings is manufactured to verify the effectiveness of the topology proposed in this research. The presented results show that this novel motor can provide a great thrust property, it has a potential in high performance industry applications.

The working environment of Planar Lightwave Circuit (PLC) optical splitter is complex and diverse. In addition to withstanding the test of environmental temperature changes, the device may also be affected by mechanical shock such as vibration. Through the thermal-vibration coupling online test, it was found that the insertion loss of the PLC optical splitter changes significantly when the vibration test is performed under high temperature and low temperature environment (the maximum insertion loss change was 4.491dB at 75 °C, and 3.941dB at −40°C). In the same temperature environment, the optical performance of the device during the lateral test and the vertical test was more affected by vibration than in the horizontal test. The study of reliability under combined vibration and temperature fields is helpful to understand and improve the ability of devices to work normally in complex environments.

Two-degree-of-freedom (2-DOF) actuators capable of producing linear/swing motion are significant for end-effectors in multidimensional complex motion platforms. This paper proposes a novel 2-DOF voice coil motor (VCM) featuring simple structure, small size, and great force properties. The structure of this novel VCM and the distribution of magnetic field are first described, the modeling of linear-thrust and swing-torque is accomplished, force properties of this 2-DOF VCM and stress analyses of the mover brackets are conducted by finite element method (FEM). Then, a prototype of this 2-DOF VCM was manufactured and tested to validate its theoretical features. In order to indicate the improvements of this proposed VCM, the force features of this motor are contrasted with the ones of a linear-swing VCM we designed previously; the simulation and experimental results of the two VCM are compared. Conclusion is drawn as that the proposed VCM has lower ripple ratios of linear-thrust and swing-torque, meanwhile, higher average values of linear-thrust and swing-torque are achieved. This paper provides a theoretical reference and experimental data of this novel 2-DOF VCM for multidimensional complex motion systems.

Cylindrical shell vibration gyroscope is a kind of solid wave gyroscope which uses the inertia effect of elastic wave to detect the rotation angular velocity. Precision dynamic balance is the key to improve the stability of gyro standing wave vibration. In this paper, precision dynamic mass-stiffness balancing along the working mode axis at the top of the resonator cup-wall is studied. The radial region of different trimming types and the variation of resonator natural frequency and frequency split with trimming hole depth are determined by the simulation. The femtosecond laser precision trimming-ablation experiment verifies the simulation results. The experiment and simulation have good consistency. This paper clearly clarifies the precision dynamic mass-stiffness balancing law of trimming along the working mode axis, which provides a guarantee for high efficiency and high precision trimming.

Precision linear motion is widely used in industrial application. For precision linear motion actuators, ripples of thrust force can deteriorate the driving performance and increase mechanical vibrations. It is very important to precisely test the thrust force of a linear motion actuator. This paper proposes a novel method based on testing reaction force and on the aerostatic method to achieve high-precision and universal testing capability. In this method, the mover and the stator of tested linear motion actuators are suspended by two air-bearing modules. In contrast to traditional testing methods, the force sensor is connected to the stator to avoid the influence of vibration on the sensor. The air-bearing modules eliminate the friction between the stator and the mover, so that it would not affect the results. To validate the strategy, a sample testing platform is manufactured, then a series of experiments is carried out, and the testing performance is compared with that of the traditional method. Experimental results demonstrate the high accuracy achieved by eliminating interferences due to friction and the vibration of the force sensor.

A novel bi-piezoelectric jet dispenser with a zoom mechanism is proposed to distribute adhesives rapidly. The work frequency of the new jet dispenser can reach 500 Hz. The volume of the minimum dot is about 25 nL, and the volume error among dots is not more than ±10%. The dot size can be controlled by adjusting the driving voltage of the piezoelectric stack, filling pressure, and the opening time of the valve. Subsystem physical models of the jet valve are presented on the basis of the bi-piezoelectric principle and the zoom mechanism, which involves an electromechanical model, dynamic model, and fluid–solid coupling model. Based on these physical models, a coupled mechanical–electrical fluid simulation model is established, which can be simulated. The simulation results of the multiphysics-coupled model are in accordance with the experiment. The coupling model will develop a reliable simulating platform for high-speed fluid jet. The effectiveness of the bi-piezoelectric method and models is confirmed, and it will provide a new technology for microelectronics packaging.

Two types of robust Mach–Zehnder interferometer (MZI) sensors based on microcavity in a single mode optical fibers (SMFs) are proposed, which are fabricated by femtosecond laser inscription and chemical etching. The SMFs are modified by an improved point-by-point inscription method (called a transversal-scanning method) or a line-by-line scanning inscription method, which lead to form a rectangular-shaped or a V-shaped MZI after etching. The MZIs show high refractive index (RI) sensitivity above $10^{\mathrm { {5}}}$ nm/RIU with good linearity. Especially, the rectangular-shaped MZI exhibits a ultra-high RI sensitivity of −17503.73 nm/RIU with a linearity of 0.999 in the range of 1.3371–1.3407. The results of which are coincident with theoretical calculation. In addition, the MZI structures have good mechanical strength and temperature sensitivities in water are also studied.

Here, we report a sapphire-based Fresnel zone plate (FZP), which is fabricated by femtosecond laser direct writing assisted with subsequent wet etching. With this method, we solved the problem of high surface roughness caused by ultrafast femtosecond laser processing. We have obtained $\sim 12$ -nm average surface roughness smaller than 1/25 of the optical working wavelength. As-formed sapphire FZP also exhibited a well-defined geometry. More importantly, ultraviolet (UV) light focusing and imaging can be easily achieved. Due to the high material hardness, thermal and chemical stabilities of sapphire, such sapphire FZP, may have great potential in UV imaging and focusing under some harsh environments.

In order to develop jetting technology in LED and microelectronics packaging, an innovative electromagnetic jet valve with zoom mechanism and opening electromagnetic coil is suggested, and an improved method of double voltage drive is applied in the electromagnetic control. It is found that the needle stroke of the new jet valve is increased to 1.3 times, and the needle velocity is raised to 1.8 times, and the temperature of opening electromagnetic coil is lowered to 6.7 °C. The jet valve can successfully jet 4 Pa·s high-viscosity adhesives at room temperature due to the improvement of dynamic characteristics. It will provide a new method for jetting high-viscosity adhesives.

As one of the major air pollutants, nitrogen dioxide (NO2) is seriously harmful to humans and the environment. The development of surface acoustic wave (SAW) sensors provides great potential for manufacturing miniaturized NO2 sensor with high sensitivity, and high stability. In this paper, a SAW NO2 sensor with a sensing layer formed by nanocomposite materials mixed with multi-walled carbon nanotubes (MWNTs) is presented. The SAW device used in this paper is a commercialized two-port Rayleigh wave resonator and the main sensitive material to NO2 is phthalocyanine copper (CuPc). In order to increase the sensitivity of CuPc to NO2 at relative low temperature, MWNTs and metal-oxide nanoparticles are doped into the sensitive films. The p-n heterojunctions formed between the metal-oxide–semiconductor and the CuPc/MWNTs sensitive materials improve the performance of the sensor at low temperature down to 50 °C. The sensor shows good linearity and repeatability to NO2 with bulk concentration of 1–80 ppm, and the sensitivity is 50.5 Hz/ppm at 50 °C.

The observation of the bright pulses and dark square pulses in a graphene-oxide saturable absorber (GOSA) passively mode-locked ytterbium-doped fiber laser has been investigated experimentally. Bright pulses are achieved at a pump power of $\sim$ 200 mW. However, the dark-square-pulse generation starts at a much higher pump power of $\sim$ 450 mW. At the maximum pump power of 600 mW, the dark-square-pulse bunches and harmonic mode locking (HML) can be also obtained by tuning the polarization controller (PC) to different orientations. It is the first demonstration of the bunches and HML of dark square pulses in a GOSA passively mode-locked ytterbium-doped fiber laser with large normal dispersion cavity.