Grating interferometers highly valued for high resolution, straightforward benchmark, and insensitivity to environmental disturbances have become one of the most mainstream methods for ultraprecision positioning. Traditional heterodyne grating interferometers which use a dual-frequency orthogonally polarized laser source suffer nanometer-level periodic nonlinear error due to frequency and polarization mixing, thus becoming incompetent to undertake sub-nanometer measurement. Based on the design of two separated laser beams with a small frequency difference for heterodyne beating, a wavelength-stabilized and quasi-common-path heterodyne grating interferometer is proposed. It incorporates a symmetrical oblique incidence structure where the residual dead path is calibrated and the laser source wavelength is stabilized to the rubidium atomic transition line, diminishing heterodyne phase errors resulted from the optical path difference. This approach not only significantly mitigates periodic nonlinear error to below 0.3 nm but also enhances measurement resolution, repeatability, and interference robustness. The proposed heterodyne grating interferometer is determined for ultraprecision positioning serving for precision machinery manufacturing and scanning beam interference lithography and so forth.

A wavelength-stabilized and quasi-common-path heterodyne grating interferometer with sub-nanometer precision

Chromatic confocal technology is widely used for precise, steady, and efficient displacement measurement in many industrial fields. It employs the confocal and dispersion principles to encode axial positions with the wavelengths of the reflected broad spectrum. The typical chromatic confocal sensor includes a light source, a dispersion objective, conjugate pinholes, and a spectral detection device. This study offers an overview of the current research on chromatic confocal technology. Because of its good performance in displacement detection, chromatic confocal technology has been widely used in contour measurement, biomedical imaging, and thickness measurements, as part of global and professional research. Due to its structural flexibility, it is also easily integrated into industrial equipment for in-machine and online profile measurements. It holds significant potential for future applications in industrial manufacturing and scientific research. However, there are also some challenges to be explored in terms of the broadband light source, dispersive optics design, and the balance between speed and accuracy in signal processing.

High-Precision Chromatic Confocal Technologies: A Review

A Pose Optimization Method for Field Measurement Accuracy Improvement of the Visual Tracking-Based Measurement System

Research on the Optimization Methods of Common Points Layout for Survey and Alignment of Particle Accelerators

In recent years, space exploration provided both stimuli and challenges for technical advancement and basic research. In this frame, to reduce space, weight, and costs, the adoption of printing electronics, to develop small and embeddable printed circuits and sensors, is a viable solution to provide electronic connections and measurements in space vessels. Regarding printed electronics (PE) techniques, aerosol jet printing (AJP) is a promising tool to depose functional materials on a plethora of substrates. However, in the literature the effects of substrates and protective coating layers are still unexplored, but relevant when high-temperature changes and harsh conditions should be withstood such as in the aerospace field. Thus, five different substrates and two coating materials were employed in this work to fabricate a set of printed conductive traces. The temperature behavior of the produced devices was evaluated to understand the effects of substrates and protective coatings. Static and dynamic tests were performed to evaluate the main metrological characteristics. The results show that materials and geometries of the substrates can influence the rise time of the printed traces by orders of magnitude. On the other hand, the different coatings gave relevant differences as regards the hysteresis error that increased on an average of 62.5% (and with peaks of over 400% in one case) and on the temperature coefficient of resistance (TCR) with an average change of 18.2%. Last, a set of insights and considerations are proposed to improve the adoption of fully PE in the aerospace field.

Substrate and Coating Effects on Temperature-Related Behavior of Silver Traces Printed by Aerosol Jet for Aerospace Applications

Laser trackers (LTs) are indispensable instruments in large-scale dimensional metrology. Nevertheless, geometric errors are prone to increase in site environments due to the occurrence of mechanical and optical misalignments, which deteriorates the measurement accuracy of the LT. The geometric error parameters are difficult to determine by traditional measuring or calibrating approaches. In this article, a classification calibration method is proposed without any other etalons or instruments that accurately estimate the geometric error parameters in a site environment. First, to determine the environmental sensitivity error parameters, a refractive index correction model in a variable temperature environment is constructed, which performs well in reducing the interference of environmental temperature fluctuations. Subsequently, a spatial measurement network is established to determine two-face sensitivity error parameters using the difference between the frontsight and backsight measurements of the targets. Finally, the two-face nonsensitivity error parameters are solved by minimizing the residuals of the coordinate transformation from each LT station to the reference frame. Indeed, the effects of temperature fluctuation and geometrical misalignments on the measurement accuracy are deeply analyzed, which provide meaningful guidance for calibration and compensation of the geometric errors of the LT. The effectiveness of the proposed method is validated by a series of site experiments. The results show that the length error is reduced to 0.030 mm on average, which is 44% lower than that of the network method.

Calibration of the Geometric Error Parameters of Laser Trackers in Site Environments

Accurate Prediction of Thermally Induced Variations in Length Measurements by Recalibration of the Coefficient of Thermal Expansion (Cte)

As the primary load-bearing structures, large-scale aircraft spars are subject to the influence of nonuniform temperatures in field conditions, resulting in thermal errors during on-site length inspections. These errors require accurate compensation. Conventional linear scaling methods, based on the assumption of uniform temperatures and a retrieved coefficient of thermal expansion (CTE), suffer from low accuracy in nonuniform temperature environments. To address this issue, this paper proposed a thermal error compensation method that incorporates CTE recalibration. First, we established a predictive model for thermal errors in nonuniform temperature fields through differential thermoelastic analysis. Secondly, a recalibration technique for the sensitive parameter, CTE, was introduced to enhance the prediction accuracy. Finally, leveraging the equivalent form of the model, an uncertainty assessment approach tailored for nonuniform temperature conditions was formulated for the compensated lengths. Numerical and case studies of a nearly 1 m long simplified wing spar were implemented to validate the performance of the thermal error compensation method. The results indicate that the presented method improved accuracy by over 57.6% in terms of RMSE compared to the linear scaling method using average temperatures, which would provide a viable approach to achieve a more accurate on-site length inspection of aircraft components. 

Thermal error compensation in length inspection of large-scale aircraft spars in nonuniform temperature environments

Online Sensing of Thermal Deformation in Complex Space Bulkheads Driven by Temperature Field Measurements

Accurate tracking of key points (KPs) in large-scale aerospace component manufacturing has been a core technology. Sensor measurement network system (SMNS) is defined as the unified benchmark to realize global position of KPs for determining position and orientation of components. However, due to multiple uncertain interferences, it is difficult to ensure the accuracy and reliability of SMNS under site conditions. To address this problem, the paper proposes an accurate and systematic construction method of large SMNS considering multiple uncertain errors. Firstly, the invalid points are eliminated based on geometric similarity of common observed information. Then, a novel model parameter identification method of SMNS with subsection dynamic weights is proposed to unify observed data from individual measurement systems in the global coordinate system. Next, a multi-level uncertainty propagation model under the combined effect of model parameter uncertainty and measurement uncertainty is presented, and a weighted fusion method based on uncertainty is further developed to calculate fused point. Finally, to further improve overall accuracy of SMNS, a configuration optimization method based on genetic algorithm by minimizing overall uncertainty is proposed to determine configurations of measurement instruments in SMNS. The influence of a series of key factors on the SMNS accuracy is analyzed in detail. Experimental results show that compared with conventional methods, the average, root mean square and maximum of point positioning errors under site conditions are reduced by 14.55 %, 17.74 % and 17.70 %, respectively. The research provides good guides of accurate construction of SMNS for in-situ manufacturing of large aerospace components. 

Accurate Construction Method of Sensor Measurement Network System for In-Situ Manufacturing of Large Aerospace Component

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Junqing Li

Author Tools

Chat about Author