Angle measurement is an essential component of precision and serves as a crucial prerequisite for high-end manufacturing. It guides the implementation manufacturing assembly. The current angle methods mainly focus on multiple axes, high precision, large ranges. This article introduces technology from perspectives single-axis multi-axis schemes. Firstly, scheme primarily achieved through optical methods, such encoder discs that measure energy changes interferometric phase changes, well...

Abstract Absolute measurement has consistently been the primary focus in development of precision linear and angular displacement measurements. The scheme design binary zero position codes is an important factor for absolute measurement. Designing optimizing high-bit with over 100 bits face considerable challenges. Simultaneously, working parameters [unit code width ( b ), distance d yaw angle α )] remarkably affect their post-installation performance, particularly positioning limit...

Grating interferometers highly valued for high resolution, straightforward benchmark and insensitivity to environmental disturbances, have become one of the most mainstream methods ultra-precision positioning. Traditional heterodyne grating which use a dual-frequency orthogonally polarized laser source suffer nanometer-level periodic nonlinear error due frequency polarization mixing, thus becoming incompetent undertake sub-nanometer measurement. Based on design two separated beams with small...

A compact and high-precision three-degrees-of-freedom (DOF; X, Y, Z directions) grating encoder based on the quadrangular frustum pyramid (QFP) prisms is proposed in this paper to solve insufficient installation space problem of reading head multi-DOF displacement measurement applications. The diffraction interference principle, a three-DOF platform built through self-collimation function miniaturized QFP prism. overall size 12.3 × 7.7 3 cm3 has potential for further miniaturization. test...

<title>Abstract</title> Planar cross-scale structures encode position and posture, enabling nanometer-level accuracy multi-scale cascaded precision, emerging as a potential sensing device for semiconductor manufacturing inspection systems. However, the fabrication of hybrid structures, which is integration spanning three orders magnitude in feature dimensions (500 nm-1.5 mm) on single substrates, still faces challenge. This requires submicron-periodic encoder arrays (reflective regions)...

An absolute-type four-degree-of-freedom (four-DOF) grating encoder that can simultaneously measure the three-axis pose (θx, θy, θz) and one-axis out-of-plane position (Z) of an object with high accuracy is demonstrated for first time in this research. This composed a stationary reading head movable reflector. A light beam from projected onto grating, three diffracted beams (0th-, +1st-, -1st-order) are generated, collimated, received by separate quadrant photodetectors (QPDs). The...

A heterodyne grating interferometer (HTGI) able to simultaneously measure the three-axis translational displacements of ultra-precision motion stages with a sub-nanometer resolution is demonstrated. The HTGI composed two main parts, reflective planar uniform micron-scale period in orthogonal directions, and reading head. Thanks grating, head design manages make optical paths common located on same side this compact structure, potentially resulting low Abbe errors environmental variations....

We propose an absolute positioning grating encoder with directional discrimination ability from coarse range to precision range, and the accuracy can reach 10 nm for a motion of several tens millimeters.

Purpose Proposing a new type of water-lubricated thrust bearing meets the load-bearing requirements high-power shaft-less rim driven thrusters. Design/methodology/approach The designs were tested by establishing thermal-fluid-magnetic comprehensive simulation model and developing fluid film force magnetic simulation. Lubrication performance tests carried out on test rig. Findings Halbach array magnet blocks is able to reach maximum force. material sheath can help increase magnetism....

Aiming at the problem that traditional water-lubricated bearing cannot carry heavy load and adapt to constantly changing operating conditions for high-power Rim Driven Thruster (RDT), principle structure of Magnetic Water-double-suspension Elastic-support Thrust Bearing (MWETB) is designed optimal parameters are selected using simulation. To demonstrate reliability MWETB under RDTs’ actual working conditions, performance tests, which include magnetic flux density, force, lubrication...

Absolute measurement has always been one of the important development directions precision measurement, there are problems that diffraction and mask working parameters not considered in positioning pulse analysis absolute code at present. Therefore, order to solve coupling optimal performance problem actual work, an should be designed for best parameter-model. In this paper, a multi-parameter model status is established, influence on its analyzed respectively. The shows distance angle...

Absolute testing for metrology has always been one of the important development directions precision measurement. The mask with binary code is an structure forming absolute positioning pulses in grating encoders. increase number codes beneficial to resolution positioning, but design existed problem that optimal cannot be obtained when increases. This paper proposes a method based on genetic algorithm, which can get required more quickly greater than 150 or even higher. specific randomly...

In terms of the heavy load and low viscosity operation conditions marine rim-driven thruster (RDT), a novel Magnetic Liquid-double-suspension Elastic-supported Thrust Bearing (MLETB) is designed. The MLETB combines structural features Rubber-supported Water-lubricated (RWTB) Permanent Magnet (PMB). To investigate axial stiffness damping bearing, dynamic model incorporating multi-layer structure developed. Simulation indicates that performance close to RWTB, but capacity better. Besides, not...

This paper presents a novel heterodyne grating interferometer designed to meet the precise measurement requirements of next-generation lithography systems and large-scale atomic-level manufacturing. Utilizing dual-frequency light source, enables simultaneous three degrees freedom. Key advancements include compact zero Dead-Zone optical path configuration, significantly enhancing reliability by mitigating impact source fluctuations air refractive index variations. A comprehensive crosstalk...

This paper presents a study on the spot location method and system based QPDs. We construct mathematical model of relationship between position variations detector responses, systematically analyzing impact size parameters accuracy. propose an ultra-precision Gaussian algorithm QPDs, along with common-path laser light source fluctuation error compensation structure method, validated through simulation experiments. The experimental results show that this scheme can achieve submicron level...

In this work, a solution based on sub-sampling technology for heterodyne signals is proposed. While achieving higher measurement resolution and speed, the performance requirements analog-to-digital converter microprocessor are greatly reduced. The signal sparse with single frequency at each moment, only its phase offset contains displacement information. We use pulse counting method to obtain periods of signal, sampler sampling rate well below signal. point can be restored through extended...

The accuracy of the absolute position and orientation sub-mirrors in large-aperture optical systems significantly impacts system performance. precision sub-mirror alignment directly affects surface shape error main mirror, which, turn, imaging quality overall Two methods for measurement are electromagnetic displacement measurement. While achieve high precision, their complex structures susceptibility to environmental factors pose challenges. Optical using grating encoders, which rely on...

High-precision position and orientation measurement plays a crucial role in modern engineering scientific fields, finding applications areas such as advanced manufacturing, aerospace, medical technology. Grating encoders are stable highly accurate solutions, particularly well-suited for multi-degree-of-freedom high-precision scenarios. <br/> This paper addresses the modeling compensation of crosstalk errors resulting from grating angle variations previously designed six-degree-of-freedom...

The heterodyne signal of a grating interferometer is formed by the interference two coherent light beams with frequency difference. equal to difference beams. When one beam undergoes Doppler shift, experiences corresponding change. By calculating phase between reference and measurement signals interferometer, displacement an object can be determined. accuracy real-time performance solving this affect overall interferometer. Multi-degree-of-freedom interferometers play crucial role in...

In order to solve the problem of mutual limitations large measurement range and high precision absolute grating encoders, this paper employs codes individually number each spliced section on substrate, leveraging asymmetric code arrangement. With light splitting ability beam splitter, source is divided into dual beams inputted encoder form a reading head. At least one can always generate stable signal within travel range, then serial area determined through codes. The signals generated by...

Six-degree-of-freedom (6-DOF) grating encoders have a wide prospect of application. Aiming at the requirement real-time detection 6-DOF encoders, this study designs and builds calculation system platform based on field-programmable gate array (FPGA). We realized parallel 16-path displacement signal 24-path angular signal, respectively. Specifically, optical interference signals, generated by translation rotation motion stages, are firstly shaped front-end analog circuit. further sampled...

Laser interferometers and grating are typical optical measurement devices. The resolution range of the two devices generally nanometers meters, so they can meet needs high-resolution, largerange measurement. Whether it is a laser interferometer or interferometer, be implemented based on technical route principle homodyne interference heterodyne interference. Heterodyne not sensitive to changes in signal amplitude DC offset, effectively avoid errors. To design highprecision displacement...

Grating interferometer has great application potential in precision measurement. In view of its miniaturization, a compact installation based on ridge prism is adopted this paper, and the interference signal with 90° phase obtained by numerical calculation. The specific scheme to divide laser beam through splitting make two beams diffract at reference two-dimensional grating measurement respectively. four diffracted light are collimated prism. groups produce prism, received photodetector....