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...

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...

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.

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...

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...

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...

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...

<title>Abstract</title> <bold>Background:</bold> The coupling coordination of population, medical care and public health system is crucial for advancing development improving governance efficiency. dramatic shifts in global population structures are reshaping demands, placing unprecedented challenges on systems. This study investigates the China from 2011 to 2021, revealing their spatiotemporal dynamic evolution. findings expected provide valuable insights promoting coordinated improve...

For solving the problem of sub-mirror installation and posture monitoring compensation, an absolute four-degree-of-freedom (DOF) grating encoder that is able to monitor four degrees freedom's position pose in θx, θy, θz, z-direction proposed. In this encoder, a reflector three quadrant photodetectors (QPD) are employed optical path configured based on laser autocollimation principle. A model for solution four-DOF motions from outputs QPDs established. calibration method identification...

For expanding the measurement range and improvement of accuracy multi-axes grating encoder, a mathematical model angle diffraction spot with QPD was established. We proposed light position calculation method consideration both optimized composite algorithm laser beam feature Gaussian distribution diagonal algorithm. In this method, we use piecewise polynomial fitting to fit solved parameters traditional Infinite integral Boltzmann function Meanwhile, introduce weight factor Composite...

Pixelated micro-polarizer array is an attractive polarization imaging device because of its real-time fully detecting capability to Stokes parameters and high integration level. However, this micro-device commonly fabricated by electron beam lithography, thus often high-cost. Since periodic unit a 2×2 four types one-dimensional (1D) gratings with different orientations (0°, 45°, 90°, 135°), low-cost grating fabrication technique, interference lithography (IL), possible be used fabricate...