Metrology

About: Metrology is a research topic. Over the lifetime, 8199 publications have been published within this topic receiving 89521 citations.

A versatile camera calibration technique for high-accuracy 3D machine vision metrology using off-the-shelf TV cameras and lenses

Abstract: A new technique for three-dimensional (3D) camera calibration for machine vision metrology using off-the-shelf TV cameras and lenses is described. The two-stage technique is aimed at efficient computation of camera external position and orientation relative to object reference coordinate system as well as the effective focal length, radial lens distortion, and image scanning parameters. The two-stage technique has advantage in terms of accuracy, speed, and versatility over existing state of the art. A critical review of the state of the art is given in the beginning. A theoretical framework is established, supported by comprehensive proof in five appendixes, and may pave the way for future research on 3D robotics vision. Test results using real data are described. Both accuracy and speed are reported. The experimental results are analyzed and compared with theoretical prediction. Recent effort indicates that with slight modification, the two-stage calibration can be done in real time.

A versatile camera calibration technique for high-accuracy 3D machine vision metrology using off-the-shelf TV cameras and lenses

Abstract: A new technique for three-dimensional (3D) camera calibration for machine vision metrology using off-the-shelf TV cameras and lenses is described. The two-stage technique is aimed at efficient computation of camera external position and orientation relative to object reference coordinate system as well as the effective focal length, radial lens distortion, and image scanning parameters. The two-stage technique has advantage in terms of accuracy, speed, and versatility over existing state of the art. A critical review of the state of the art is given in the beginning. A theoretical framework is established, supported by comprehensive proof in five appendixes, and may pave the way for future research on 3D robotics vision. Test results using real data are described. Both accuracy and speed are reported. The experimental results are analyzed and compared with theoretical prediction. Recent effort indicates that with slight modification, the two-stage calibration can be done in real time.

Frequency Ratio of Al+ and Hg+ Single-Ion Optical Clocks; Metrology at the 17th Decimal Place

Abstract: Time has always had a special status in physics because of its fundamental role in specifying the regularities of nature and because of the extraordinary precision with which it can be measured. This precision enables tests of fundamental physics and cosmology, as well as practical applications such as satellite navigation. Recently, a regime of operation for atomic clocks based on optical transitions has become possible, promising even higher performance. We report the frequency ratio of two optical atomic clocks with a fractional uncertainty of 5.2 × 10–17. The ratio of aluminum and mercury single-ion optical clock frequencies νAl+/νHg+ is 1.052871833148990438(55), where the uncertainty comprises a statistical measurement uncertainty of 4.3 × 10–17, and systematic uncertainties of 1.9 × 10–17 and 2.3 × 10–17 in the mercury and aluminum frequency standards, respectively. Repeated measurements during the past year yield a preliminary constraint on the temporal variation of the fine-structure constant α of ![Formula][1] . [1]: /embed/tex-math-1.gif

Handbook of Surface Metrology

Abstract: Foreword by Professor D. Dowson GENERAL PHILOSOPHY OF MEASUREMENT Where does surface metrology fit in engineering metrology? Importance of surface metrology SURFACE CHARACTERIZATION-THE NATURE OF SURFACES AND THE SIGNALS OBTAINED FROM THEM Surface roughness characterization Waviness Errors of form Comparisons of definitions for surface metrology and coordinate measuring Characterization of defect shapes on the surface PROCESSING Digital methods Digital properties of random surfaces Fourier transform and the FFT Statistical parameters in digital form Properties and implementation of ambiguity function and Wigner distribution function Digital estimation of reference lines for surface metrology Algorithms Transformation in surface metrology Graphical methods Other methods of processing Surface generation INSTRUMENTATION Introduction and historical Measurement systems Optical techniques for measurement of surfaces Capacitance techniques for measurement of surfaces of slopes Inductance techniques Impedance technique-skin effect Other non-standard techniques Electron microscopy Merit of transducers ERRORS, CALIBRATION, TRACEABILITY AND STANDARDIZATION Nature of errors Deterministic or systematic error model Basic components of accuracy evaluation Basic error theory for a system Propagation of errors Some useful statistical tests for surfaces Uncertainty in instruments-calibration in general Calibration of stylus instruments Calibration of form instruments Parameter variation National and international standards Drawing symbols SURFACE METROLOGY IN MANUFACTURE Manufacturing processes Cutting Abrasive processes Unconventional machining Surface roughness produced by machining difficult materials Surface effects other than geometry Surface geometry-a fingerprint of manufacture SURFACE GEOMETRY-ITS IMPORTANCE IN FUNCTION Two body interaction - static effects Functional properties of contact Two body interactions - dynamic effects General roughness and system life One body interactions One body with radiation (optical) Scattering by other waves Systems function SUMMARY AND CONCLUSIONS Characterization and nature of signal Data processing Measurement of trends Calibration Manufacture Function Overview

Application of acoustic resonators in photoacoustic trace gas analysis and metrology

Abstract: The application of different types of acoustic resonators such as pipes, cylinders, and spheres in photoacoustics is considered. This includes a discussion of the fundamental properties of these resonant cavities. Modulated and pulsed laser excitation of acoustic modes is discussed. The theoretical and practical aspects of high-Q and low-Q resonators and their integration into complete photoacoustic detection systems for trace gas monitoring and metrology are covered in detail. The characteristics of the available laser sources and the performance of the photoacoustic resonators, such as signal amplification, are discussed. Setup properties and noise features are considered in detail. This review is intended to give newcomers the information needed to design and construct state-of-the-art photoacoustic detectors for specific purposes such as trace gas analysis, spectroscopy, and metrology.