Готові списки джерел за темами / Length metrology

Добірка наукової літератури з теми "Length metrology"

Автор: Grafiati
Опубліковано: 14 березня 2023

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Статті в журналах з теми "Length metrology"

1

Lee, Dong-Yeon, Dong-Min Kim, and Dae-Gab Gweon. "Atomic Force Microscope for Standard Length Metrology." Transactions of the Korean Society of Mechanical Engineers A 30, no. 12 (December 1, 2006): 1611–17. http://dx.doi.org/10.3795/ksme-a.2006.30.12.1611.

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2

Stone, Jack A. "Uncalibrated Helium-Neon Lasers in Length Metrology." NCSLI Measure 4, no. 3 (September 2009): 52–58. http://dx.doi.org/10.1080/19315775.2009.11721483.

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3

García-Asenjo, Luis, Sergio Baselga, Chris Atkins, and Pascual Garrigues. "Development of a Submillimetric GNSS-Based Distance Meter for Length Metrology." Sensors 21, no. 4 (February 6, 2021): 1145. http://dx.doi.org/10.3390/s21041145.

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Анотація:
Absolute distance determination in the open air with an uncertainty of a few tenths of a millimetre is increasingly required in many applications that involve high precision geodetic metrology. No matter the technique used to measure, the resulting distances must be proven consistent with the unit of length (SI-metre) as realized in the outdoor facilities traditionally used in length metrology, which are also known as calibration baselines of reference. The current calibration baselines of reference have distances in the range of 10 to 1000 m, but at present there is no solution on the market to provide distances with submillimetric precision in that range. Consequently, new techniques such as multi-wave interferometry, two-wave laser telemeters or laser trackers are being developed. A possible alternative to those sophisticated and expensive techniques is the use of widely used Global Navigation Satellite Systems (GNSS) in order to provide a GNSS-Based Distance Meter (GBDM). The use of a GBDM as a potential technique for length metrology has been thoroughly analysed in several European research projects by using the state-of-the-art geodetic software, such as Bernese 5.2, but no definite conclusions have been drawn and some metrological questions are considered still open. In this paper, we describe a dedicated approach to build up a submillimetric GBDM able to be applied in the current calibration baselines of reference, as well as possible methods to cope with the multipath error of the GNSS signals which is the major limitation for the practical uptaking of the technique in metrology. The accuracy of the proposed approach has been tested following the length metrology standards in four experiments carried out in the Universitat Politècnica de València (UPV). The results demonstrate that the proposed GBDM can provide an accuracy of a few tenths of a millimetre in the current calibration baselines of reference.
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4

Buchta, Zdeněk, Martin Šarbort, Martin Čížek, Václav Hucl, Šimon Řeřucha, Tomáš Pikálek, Štěpánka Dvořáčková, et al. "System for automatic gauge block length measurement optimized for secondary length metrology." Precision Engineering 49 (July 2017): 322–31. http://dx.doi.org/10.1016/j.precisioneng.2017.03.002.

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5

Wieczorowski, Michał, Paweł Pawlus, and Bartosz Gapiński. "Perspectives of modern metrology." Mechanik 92, no. 12 (December 9, 2019): 767–73. http://dx.doi.org/10.17814/mechanik.2019.12.106.

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Анотація:
The most up-to-date trends in development of length and angle metrology were presented. This development falls within a concept of Industry 4.0 and is understood as Metrology 4.0. Basic elements of these concepts and their connections were shown during years in relation to consecutive industrial revolutions. Specific issues regarding additive technologies were described with a view to functional filtration. Achievements of coordinate measuring technique in macro scale were also presented including optical scanning and computed tomography. In conclusions standardization works regarding the mentioned topics were described.
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6

TANAKA, Shinichi. "Non-Contact 3D Metrology by Multi Wave-Length Interferometer." Journal of the Japan Society for Precision Engineering 85, no. 8 (August 5, 2019): 695–98. http://dx.doi.org/10.2493/jjspe.85.695.

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7

Blumröder, Ulrike, Ronald Füßl, Thomas Fröhlich, Eberhard Manske, and Rostyslav Mastylo. "FREQUENCY COMB-COUPLED METROLOGY LASERS FOR NANOPOSITIONING AND NANO MEASURING MACHINES." Measuring Equipment and Metrology 82, no. 4 (2021): 36–42. http://dx.doi.org/10.23939/istcmtm2021.04.036.

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This article shows how a direct readout of the interferometric length measurement in nanopositioning machines can be transferred by connecting the metrology laser to a frequency comb line. The approach is based on a GPS-referenced frequency comb with which the stability of the timer (atomic clock via GPS) is transferred to the metrology laser of the nanopositioning and nano measuring machine NPMM-200. The necessary prerequisites for ensuring traceability are discussed. It is demonstrated that with this approach an improvement in the long-term stability of the metrology laser by three orders of magnitude can be achieved.
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8

Jing, Ren, and Xin Chang. "A determinate method of metrology attribute benchmark of commercial banks’ management efficiency." PLOS ONE 17, no. 8 (August 4, 2022): e0272286. http://dx.doi.org/10.1371/journal.pone.0272286.

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The evaluation or metrology of commercial bank management efficiency is the core of its effective management. The existing management efficiency of commercial banks adopts evaluation scheme rather than metrology. There are four shortcomings with the evaluation scheme, the evaluation is a ranking of advantages and/or disadvantages, all objects should participate in the evaluation, the evaluation results are valid only for the evaluated objects, and the evaluation results lack the metrology benchmark of the object domain. To address this issue, the paper presents a method to determine the benchmark of management efficiency, which is similar to the unit "meter" in the metrology of "length" and the unit "scale" in the metrology of "management efficiency". Firstly, the method of cluster analysis is used to solve the problem of attribute metrology base of management efficiency metrology. Based on the master of certain attribute data of commercial bank management efficiency metrology, cluster analysis is carried out onto the attribute data, and its characteristics and patterns are mined to determine the candidate benchmark set. Secondly, in the candidate datum set, k-means method is used to determine the metrology attribute datum to obtain the general metrology attributes. Finally, the absolute metrology of management efficiency is carried out for any commercial bank according to the benchmark, and the validity and feasibility of the benchmark are verified with an example. In such a way, the deficiencies of four aspects of evaluation are solved. Such a strategy can be adapted to different banks at any different time for their respective measurement, which extends the clustering statistical methods for attribute datum determination. The results can be applied to some other fields wherein object metrology is the basic task.
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9

Mateo, Ana Baselga, and Zeb W. Barber. "Precision and accuracy testing of FMCW ladar-based length metrology." Applied Optics 54, no. 19 (June 26, 2015): 6019. http://dx.doi.org/10.1364/ao.54.006019.

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10

Röske, Dirk. "Some problems concerning the lever arm length in torque metrology." Measurement 20, no. 1 (January 1997): 23–32. http://dx.doi.org/10.1016/s0263-2241(97)00006-7.

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Більше джерел

Дисертації з теми "Length metrology"

1

Barwood, Geoffrey P. "Frequency stabilised laser diodes and their use in length metrology." Thesis, University of Kent, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314498.

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2

SANTAGATA, ROSA. "Sub-nanometer length metrology for ultra-stable ring laser gyroscopes." Doctoral thesis, Rosa Santagata, 2015. http://hdl.handle.net/11365/1004514.

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Анотація:
Large-frame ring laser gyroscopes are extremely sensitive inertial detectors of rotational motion. When properly coupled to the ground, they provide precise measurements of the Earth rotation rate and give important informations to geodesy and geophysics. Recent advances in this technology led to consider the application of ring laser gyroscopes to fundamental physics. In this context is GINGER (Gyroscopes IN GEneral Relativity), a scientic proposal for testing General Relativity (local observation of the Lense-Thirring eect) with a ground-based array of ring laser gyroscopes. The experimental target is to locally measure the Earth rotation rate with a relative precision better than one part in 109, corresponding to an absolute rotational resolution of 10−14 rad/s. The main factor limiting the performances of the presently most stable ring laser gyroscopes is the uncontrolled deformation of their optical cavity, since instabilities in the cavity geometry introduce systematic errors in the rotational signal. Cavity geometry is typically kept stable by using monolithic frames made of ultra-low thermal expansion materials, and operating in very well isolated environments. An alternative approach is based on the active control of the shape in heterolithic cavities, by measuring and stabilizing the mirrors positions by means of laser-based length metrology. The goal of this thesis is the development of a stabilization system based on interferometric length metrology, with a view to improve the sensitivity of the new generation square ring laser gyroscopes, going beyond the level achievable with passive methods. The main idea proposed in this work is to exploit the diagonal resonators formed by opposite cavity mirrors, and to use their lengths as observables to constraint, against an optical reference standard, residual deformation degrees of freedom of the square cavity. As a rst step, a detailed model of the light propagation along the square cavity has been developed. This allowed us to quantify the eectiveness of the v xed length constraint of the diagonal resonators, and gave precise indications for the optimization strategy of the residual degrees of freedom. The optical frequency reference is a helium neon laser stabilized to the iodine molecular absorption. Since the power emitted by this laser is of only 300 µW, an optical amplier, based on the injection locking of a 15 mW diode laser, has been developed to guarantee a proper signal to noise ratio in the interferometric absolute length measurements. To stabilize the absolute lengths of the two diagonals, we proposed an original experimental method for the determination of both the optical resonance frequency and the free spectral range of each cavity. It is based on a triple-frequency modulation of the interrogating laser beam by electro-optic modulators. In a rst tabletop experiment, the method has been veried on two Fabry-Perot resonators that, composed by couples of spherical mirrors typically used in the He-Ne ring cavities, simulate the diagonals of a ring laser gyroscope on an optical bench. Here, the capability of setting equal the two lengths at the level of 500 nm, with residual uctuations only limited by the laser frequency noise, has been experimentally proved. As a nal result, we have applied the developed method to lock the diagonal cavities lengths of GP2 ring laser gyroscope, a square cavity 1.6 m in side length dedicated to the interferometric control of the cavity geometry deformations, and fully set up at the INFN laboratories in Pisa in June 2015
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3

Gedela, Naga Venkata Praveen babu. "MEASUREMENT AND ITS HISTORICAL CONTEXT." Kent State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=kent1226037175.

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4

Donaldson, Claire Louise. "Spine characteristics in sheep : metrology, relationship to meat yield and their genetic parameters." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/20381.

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The overall accuracy, efficiency and profitability of livestock improvement strategies can be greatly increased by incorporating quantitative genetics into livestock selection and breeding. Since the introduction of quantitative genetics, a range of traits describing the animal e.g. in terms of health, growth, fecundity, production, have been extensively evaluated in terms of genetics and are now commonly manipulated through breeding to achieve specific selection goals. An industry led enquiry as to the possibility of including spine traits in genetic selection to increase back length in sheep was the basis of the present thesis. Collecting information on spine traits (spine length, vertebrae length and vertebrae number) is of particular interest and use to the sheep breeding industry as there may be the potential to increase meat yield from the highly valuable longissimus thoracis et lumborum (LTL or loin), located parallel to the spine, with little associated change in production costs. The thesis focusses on the use of X-ray computed tomography (CT) scanning as a technique which would allow spine traits to be measured in vivo, hence being useful for genetic selection. The topogram scans produced from the CT scanning procedure were analysed to derive spine trait information for the thesis. The scans were from Scottish Blackface (maternal breed stock), Texel (terminal sire breed), Texel cross Mule and Poll Dorset cross Mule (three-way cross slaughter lambs) so as to represent the divergent genotypes found across the different levels of the United Kingdom’s (UK) three-tier crossbreeding structure of sheep. The present study explored as a first step intra- and inter-operator repeatability of assessment of spine traits from CT derived topograms, as a means to investigate the suitability of the approach for widespread uptake within industry where operators will vary. The results showed that there was high repeatability for intra- and inter-operator assessment of spine trait measurements verifying that the CT method could be accepted as a reliable alternative (to slaughter for example) to quantify spine traits. To determine whether spine traits are similar across the range of breeds representing the key genotypes and crosses in the UK sheep industry, numerous CT topograms were analysed. The results showed marked variation in spine traits within and between Scottish Blackface, Texel, Texel cross Mule and Poll Dorset cross Mule breeds and crosses. For example, the Texel breed was found to have the largest within-breed range for thoracolumbar vertebrae number (17 – 21; the majority possessing 19), but the spine length of these animals was, on average, significantly shorter than the other breed/cross groups. The present study concluded that the significant differences between the breeds and breed types for the particular spine traits were possibly indicative of a genetic control for these traits. Furthermore, investigation into the phenotypic correlations between spine and production traits revealed some directional associations which may prove beneficial for meat production. For example, Scottish Blackface lambs which had a longer length of a specific spine region had an associated decrease in the volume of carcass fat. Texel lambs which had a longer length of a specific spine region had a slightly larger loin muscle area, at a given weight. The present study also examined animals from a population of Texel lambs already heavily selected for increased muscling. The Texel muscling quantitative trait locus (TM-QTL), segregating in these animals and generally in the UK’s Texel sheep population, is expressed through a polar overdominance pattern of inheritance and its effect on the loin (localised muscle hypertrophy) is commonly utilised in the selection and breeding of Texel sheep to improve meat production. Examination of topograms from lambs bearing the whole range of TM-QTL genotypes showed little evidence to suggest that the change in loin shape/increased loin muscling, as a result of the TM-QTL and its inheritance, has led to any associated change in the underlying spine characteristics. This suggests that selection for increased muscling associated with the TM-QTL may be achieved independently of changes in the spine traits studied. The potential to breed for certain spine traits to increase vertebrae number and hence chops or loin yield can be enhanced by establishing the genetic parameters for the traits. The present study employed a collection of performance trait records from Texel lambs to provide the basis for genetic analysis. The results showed different levels of heritability for the different spine traits but also high standard errors. For example, heritability of vertebrae number was dependent on vertebra location: for thoracic vertebrae heritability was high (ℎ2 = 0.99; SE = 0.42), for lumbar vertebrae heritability was low (ℎ2 = 0.08; SE = 0.12), whereas in contrast, thoracolumbar vertebrae heritability was moderate (ℎ2 = 0.44; SE = 0.27). Phenotypic and genetic correlations between all combinations of traits were also obtained. Accurate predictions of the size and direction of response to selection can be achieved through such genetic analysis of traits. The more that is known of the genetic characteristics of traits and their genetic correlations with other economically important traits, the more efficiently it can be built into breeding programmes improving the overall performance of stock. The results of this study showed that providing spine measurements can contribute to the diversity of trait information available to breeders. The present study also suggests that there may be opportunities to select for increased spine length/vertebrae number which would benefit the sheep industry in terms of increased chop number/loin yield. Although more data are needed prior to implementation. Practical uptake of selection for spine traits would be enhanced due to the straightforward nature of the measurements and the high operator repeatability.
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5

APRILE, GIULIA. "Directed self-assembly of Di-Block copolymers for a new idea of length standards at the nanoscale." Doctoral thesis, Università del Piemonte Orientale, 2017. http://hdl.handle.net/11579/86901.

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Di-Block Copolymers (DBCs) are materials composed of two different monomer subunits linked together. These blocks are able to self-assemble in different microphases with various morphologies (cylinders, lamellae, spheres, gyroids). For this reason, the DBCs are widely investigated as patterning and nanofabrication technique. In this work, the combination of conventional lithographic approaches with the Self-Assembly of DBCs is investigated, to develop a new generation of lateral length standards at the nanoscale (under 70 nm) with a low cost approach based on the natural constants of matter. The behavior of a cylinder forming Polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) with Mn = 54 kg·mol-1 within SiO2 periodical trenches by a Rapid Thermal Processing (RTP) oven is studied. Although this material has been widely used as lithographic mask its application in metrology field was still unknown. The optimization and calibration of DBC thin film deposition processes as a function of geometrical and annealing parameters are performed and the characteristic dimensions (L0) of the cylindrical patterns are analyzed. A decoupling of the L0 along the two confinement directions is observed. The center-to-center distance in the direction parallel to the long side of the trenches (L0l) remains invariant as a function of process variability. Thus, the high stability of L0l makes it an intrinsic feature of the system usable as measurand for a new lateral length standard. Finally, the attempt to increase the chemical incompatibility between the two blocks within the PSb-PMMA system by copolymerization of a fluorine containing methacrylic monomer with the methyl methacrylate is performed. The aims are to understand how the fluorine-containing monomer influences the DBC segregation and the structure periodicity, and if this modification allows to obtain a smaller periodicity of the DBC features for potentially increasing the standard length size range.
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6

Holá, Miroslava. "Pokročilé interferometrické metody pro souřadnicové odměřování." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-364822.

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Анотація:
This thesis addresses particular topics in the field of the length metrology for nanometrology. Nanometrology deals with dimensional measurements of micro- and nanostructures with a high spatial resolution. It typically combines a microscope imaging with a precise coordinate measurement, usually capable of nanometre resolution using the state-of-art laser interferometry techniques. The development in this field is driven, among others, by emerging advanced nanotechnologies that demand to push further the capabilities and limits of the interferometric techniques to make the nanometre-level dimensional measurement of nanostructures possible. The principal limitations of current systems are the environmental conditions and especially the fluctuations in the refractive index of air. The theoretical part of this thesis aim at analysis of individual parts of laser interferometer. I oriented myself on the study of their advantages/disadvantages and further also the possibilities of their industrial applications. The second part of the thesis presents my work that focused on the influence of the refractive index of air (RIA) on the measurement uncertainty. I experimentally demonstrated an interferometric system with a self-cancellation RIA fluctuations: a transparent photodetector is used for the measurement of the standing wave along the axis of a passive resonator, where the resonator also serves as a reference for the laser wavelength stabilisation. Another optical arrangement, based on a setup of several Michelson interferometers, represents a combination of an interferometer and a refractometer into a single system. This setup was used to study the behaviour of the ambient airflow with respect to the optical path difference and physical separation of the interferometer’s and refractometer’s path. Based on the experimental results I proposed new arrangements for shape measuring interferometers, which combine length interferometry and a tracking refractometer for the direct compensation of RIA fluctuations with geometrically adjacent optical beams. The results indicate an improvement in RIA fluctuation induced uncertainty by a factor of 100. Third part describes the design and implementation of interferometric systems for specific applications. For the industrial environment I developed a compact interferometric displacement gauge which is designed to allow nanometre level measurement using a simplified interferometer construction. For coordinate measurement of the position of the sample up to six degrees of freedom, I realised a compact modular interferometric system, which represents a unique setup together with a stabilised laser source. To measure the position of the sample in an electron beam writer chamber, I designed and implemented a differential interferometer that works in the near infrared domain and uses a new detection method developed for this system. In the fourth part I describe the realisation of a high-speed interferometer with a differential arrangement, which allows evaluation of high-cycle fatigue in material engineering. This method of studying high-cycle fatigue should be beneficial for both the basic research and the engineering practice.
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7

Hopper, David J. "Investigation of laser frequency stabilisation using modulation transfer spectroscopy." Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/16667/1/David_John_Hopper_Thesis.pdf.

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Анотація:
Optical frequency standards are necessary tools for accurate measurement of time and length. In practice these standards are stabilised laser systems locked to a known frequency reference. These references are typically the resonant frequencies of the atoms of an absorption medium that have been theoretically calculated to a high degree of accuracy. This thesis describes a combination of experimental and theoretical research performed on modulation transfer spectroscopy (MTS)--a technique used to frequency stabilise a laser in order to produce an accurate frequency reference--with emphasis placed on developing techniques and procedures to overcome the limitations found in existing MTS stabilised laser systems. The focus of the thesis is to generate a highly accurate frequency reference by researching the system parameters that will increase the signal to noise ratio and improve the accuracy of the reference through refinement of the signal structure. The early theoretical interpretation of MTS was effectively a low absorption approximation that occurs at low pressures. This approximation ignores the depletion of beam energy through absorption and is a distinct limitation of the theoretical model in its ability to accurately predict the influence of a range of system parameters on signal strength and structure. To overcome this limitation a 3-D (or volumetric) analysis was developed and is presented here for the first time. This volumetric model is a measure of two depleted beams interacting collinearly in an absorbing medium of iodine and is described to accurately predict the signal maximum as a function of pressure for all wavelengths. This model was found to be more accurate in predicting the influence of system parameters on the signal strength and structure, including that of pump beam intensity, pressure, saturation parameter, cell length and modulation parameters. The volumetric model is a novel approach to MTS theory but is more complex computationally than the traditional low pressure model and therefore more difficult to implement in many situations. To overcome this problem a hybrid model was developed as a combination of the low pressure and volumetric models. The comparison between the rigorous volume model and the hybrid model indicate that there is a deviation in the signal strength at high pressures. However, the agreement was very good in the pressure regimes that are commonly used to realise actual frequency references. Comparison of the hybrid model to experimental data was performed over a range of different wavelengths (532 nm, 543.5 nm, 612 nm and 633 nm) and found to be in close agreement. This gives confidence in the model to accurately predict signal strength and structure in any situation. Three mechanisms have been identified that limit the accuracy of frequency references due to the creation of residual amplitude modulation (RAM) where it shifts the frequency of the reference. The influence of RAM is included in the hybrid model as a ratio of the amplitude modulated and frequency modulated components of the saturating beam. These RAM production mechanisms result from the modulation of the saturating beam, the overlap of the beams in the medium, and the differential absorption of the sidebands in the medium. While the first mechanism has been previously reported the latter two are discussed here in detail for the first time. RAM generated by the modulators used (acousto-optic or electro-optic modulators) was typically of the order of 10% to 12%, depending on the excursion of the created sidebands. RAM generated by an asymmetric beam overlap with the modulators used was found to be as large as 30%. A combination of these two independent mechanisms can be used to provide a "RAM-free" state of the system by using one to cancel the effects of the other. The third RAM generation process--medium induced RAM--is difficult to remove but through a careful combination of absorption related parameters--namely, pump intensity, cell length, pressure and detector phase--the effects of RAM can be removed, leading to a distortion free MTS signal. Further investigation into the predictions provided by the hybrid model shows that there is a complex relationship between cell length and the optimum pressure required for maximum signal strength, such that longer cell lengths will not necessarily improve the signal strength. This is contrary to conventional thinking and is important in the MTS design process to reduce unnecessary costs and improve the signal to noise ratio and frequency accuracy. Optimisation of frequency stabilised laser systems using MTS are generally performed using trial and error. Comparison of these optimum parameter values to those predicted by the hybrid model show that for popular wavelengths such as 532 nm they are similar. In addition, the hybrid model is able to predict the frequency shifts that arise within the system parameters used and has shown that existing systems being used at 532 nm, 633 nm and 778 nm could improve their signal to noise ratio and accuracy through a variation in the parameters. A methodology based on the hybrid model is presented that can be used to calculate the optimum parameters for maximum signal strength and a "RAM-free" state for any wavelength. This systematic approach can therefore be used to guide the design of actual frequency stabilised laser systems prior to and during the design process.
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8

Hopper, David J. "Investigation of laser frequency stabilisation using modulation transfer spectroscopy." Queensland University of Technology, 2008. http://eprints.qut.edu.au/16667/.

Повний текст джерела
Анотація:
Optical frequency standards are necessary tools for accurate measurement of time and length. In practice these standards are stabilised laser systems locked to a known frequency reference. These references are typically the resonant frequencies of the atoms of an absorption medium that have been theoretically calculated to a high degree of accuracy. This thesis describes a combination of experimental and theoretical research performed on modulation transfer spectroscopy (MTS)--a technique used to frequency stabilise a laser in order to produce an accurate frequency reference--with emphasis placed on developing techniques and procedures to overcome the limitations found in existing MTS stabilised laser systems. The focus of the thesis is to generate a highly accurate frequency reference by researching the system parameters that will increase the signal to noise ratio and improve the accuracy of the reference through refinement of the signal structure. The early theoretical interpretation of MTS was effectively a low absorption approximation that occurs at low pressures. This approximation ignores the depletion of beam energy through absorption and is a distinct limitation of the theoretical model in its ability to accurately predict the influence of a range of system parameters on signal strength and structure. To overcome this limitation a 3-D (or volumetric) analysis was developed and is presented here for the first time. This volumetric model is a measure of two depleted beams interacting collinearly in an absorbing medium of iodine and is described to accurately predict the signal maximum as a function of pressure for all wavelengths. This model was found to be more accurate in predicting the influence of system parameters on the signal strength and structure, including that of pump beam intensity, pressure, saturation parameter, cell length and modulation parameters. The volumetric model is a novel approach to MTS theory but is more complex computationally than the traditional low pressure model and therefore more difficult to implement in many situations. To overcome this problem a hybrid model was developed as a combination of the low pressure and volumetric models. The comparison between the rigorous volume model and the hybrid model indicate that there is a deviation in the signal strength at high pressures. However, the agreement was very good in the pressure regimes that are commonly used to realise actual frequency references. Comparison of the hybrid model to experimental data was performed over a range of different wavelengths (532 nm, 543.5 nm, 612 nm and 633 nm) and found to be in close agreement. This gives confidence in the model to accurately predict signal strength and structure in any situation. Three mechanisms have been identified that limit the accuracy of frequency references due to the creation of residual amplitude modulation (RAM) where it shifts the frequency of the reference. The influence of RAM is included in the hybrid model as a ratio of the amplitude modulated and frequency modulated components of the saturating beam. These RAM production mechanisms result from the modulation of the saturating beam, the overlap of the beams in the medium, and the differential absorption of the sidebands in the medium. While the first mechanism has been previously reported the latter two are discussed here in detail for the first time. RAM generated by the modulators used (acousto-optic or electro-optic modulators) was typically of the order of 10% to 12%, depending on the excursion of the created sidebands. RAM generated by an asymmetric beam overlap with the modulators used was found to be as large as 30%. A combination of these two independent mechanisms can be used to provide a "RAM-free" state of the system by using one to cancel the effects of the other. The third RAM generation process--medium induced RAM--is difficult to remove but through a careful combination of absorption related parameters--namely, pump intensity, cell length, pressure and detector phase--the effects of RAM can be removed, leading to a distortion free MTS signal. Further investigation into the predictions provided by the hybrid model shows that there is a complex relationship between cell length and the optimum pressure required for maximum signal strength, such that longer cell lengths will not necessarily improve the signal strength. This is contrary to conventional thinking and is important in the MTS design process to reduce unnecessary costs and improve the signal to noise ratio and frequency accuracy. Optimisation of frequency stabilised laser systems using MTS are generally performed using trial and error. Comparison of these optimum parameter values to those predicted by the hybrid model show that for popular wavelengths such as 532 nm they are similar. In addition, the hybrid model is able to predict the frequency shifts that arise within the system parameters used and has shown that existing systems being used at 532 nm, 633 nm and 778 nm could improve their signal to noise ratio and accuracy through a variation in the parameters. A methodology based on the hybrid model is presented that can be used to calculate the optimum parameters for maximum signal strength and a "RAM-free" state for any wavelength. This systematic approach can therefore be used to guide the design of actual frequency stabilised laser systems prior to and during the design process.
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9

Royo, Royo Santiago. "Topographic measurements of non-rotationally symmetrical concave surfaces using Ronchi deflectometry." Doctoral thesis, Universitat Politècnica de Catalunya, 1999. http://hdl.handle.net/10803/6745.

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El objetivo de la presente Tesis es el desarrollo de un sistema de medidas topográficas de superficies sin simetría de rotación, que se ha aplicado a superficies toroidales. No tenemos constancia de que este tipo de medidas se haya realizado mediante deflectometría Ronchi. La misma obtención de topografías es un proceso poco frecuente incluso cuando las muestras son de revolución y la deflectometría Ronchi clásica tiene plena validez.

Esta Tesis Doctoral, redactada en inglés, se ha dividido en ocho capítulos:

En su primer capítulo se introduce a lector en el entorno en el que se ha desarrollado el trabajo, y se presenta la novedad de la propuesta.

En el segundo se presenta una revisión del estado actual de las diferentes técnicas de perfilometría por medios ópticos. Se incide especialmente en las técnicas más próximas a la deflectometría Ronchi, como la microscopía confocal y las técnicas interferométricas y deflectométricas (Moiré y Hartmann).

El tercer capítulo justifica el modelo teórico, utilizado para obtener las topografías de superficies cóncavas reflectoras. Se parte tanto de la interpretación basada en la Óptica Geométrica como la basada en la Óptica Ondulatoria, llegándose a la conclusión de que el modelo geométrico es suficiente si las frecuencias de la red de muestreo utilizada son bajas (menores que 3 líneas por milímetro).

En el cuarto capítulo se detalla el montaje experimental y el procesado de los datos que permite la obtención de la topografía de la superficie.

A lo largo del quinto capítulo se discuten técnicas de mejora de las medidas obtenidas, descartándose el incremento de frecuencia en la red y las técnicas de desplazamiento de fase, y aportándose una nueva técnica basada en la superposición de medidas obtenidas mediante la composición de registros que se diferencian en un desplazamiento conocido de la red de Ronchi.

El sexto capítulo muestra la validez de la técnica propuesta mediante la medida de distintas superficies esféricas, cuyos radios se comparan con valores de referencia obtenidos utilizando un radioscopio. Esta operación se repite satisfactoriamente en tres posiciones diferentes de las muestras, demostrando que el montaje experimental está adecuadamente calibrado.

El séptimo capítulo aborda la medida de distintas superficies toroidales, cuyos valores de radios de curvatura y posición de los meridianos principales se miden adecuadamente. Estas medidas se han obtenido para tres posiciones y cuatro orientaciones diferentes en cada muestra, demostrando la robustez del método.

En el octavo capítulo se presentan las conclusiones del trabajo, que se pueden resumir en:
- Se ha desarrollado un sistema para la medida de topografías de superficies con y sin simetría de rotación, a partir de una aproximación geométrica a la deflectometría Ronchi clásica. El montaje experimental que hemos desarrollado incluye algoritmos de software de tratamiento de imágenes, cálculo matemático y control de motores, programados por nosotros mismos en lenguaje C.
- Se ha mejorado el muestreo de la deflectometría Ronchi clásica mediante la composición de diferentes datos experimentales obtenidos mediante desplazamientos sucesivos y conocidos de la red de Ronchi. Se ha justificado como inviable la aplicación de técnicas de desplazamiento de fase a deflectometría Ronchi sin asumir hipótesis adicionales.
- Tanto la topografía como los residuos de la mejor superficie ajustada se han calculado para seis muestras esféricas, en tres posiciones diferentes, y para seis muestras tóricas, en tres posiciones y cuatro orientaciones diferentes. Las medidas obtenidas han permitido apreciar de modo fiable características submicrométricas de las muestras independientemente de su posición y orientación.

En la última sección se describen la bibliografía y referencias utilizadas en el trabajo.
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Книги з теми "Length metrology"

1

Fornaro, Arcangelo. Problemi di metrologia nell'opera di Polibio. Bari: Edipuglia, 2005.

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2

Shevcov, Vyacheslav. Auxiliary historical disciplines: historical Metrology of Russia. ru: INFRA-M Academic Publishing LLC., 2020. http://dx.doi.org/10.12737/1048877.

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The textbook sets out the basics of historical Metrology, presents the historiography of the discipline, and describes its sources, methods, and research approaches. The features of the formation and development of the main Russian measures and their application are considered in the General context of the economic and cultural history of the Russian state and society, the development of scientific and technical knowledge. The appendices contain the program of lectures on historical Metrology, control questions on the course, topics of possible abstracts, a list of sources, textbooks and literature, the main Russian dometric measures of length, area, volume and weight. For students of historical faculties of higher educational institutions.
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3

Malagola, Gianfranco. La metrologia dimensionale per l'industria meccanica: Aspetti teorici e pratici nelle misure di lunghezza per la determinazione delle specifiche geometroche dei prodotti. [Torino]: Augusta-Mortarino, 2004.

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4

Schodel, Rene. Modern Interferometry for Length Metrology: Exploring Limits and Novel Techniques. Iop Publishing Ltd, 2019.

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5

Schödel, Professor René, Dr Florian Pollinger, and Dr Arnold Nicolaus. Modern Interferometry for Length Metrology: Exploring limits and novel techniques. Institute of Physics Publishing, 2018.

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6

Olesko, Kathryn M. Physics and Metrology. Edited by Jed Z. Buchwald and Robert Fox. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199696253.013.24.

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This article traces the history of the relationship between physics and metrology, or physical metrology. It first examines how metrology became a part of the concerns of historians of science, and particularly physics, citing the work of Alexandre Koyré, Thomas Kuhn, and Witold Kula. It then describes various approaches to physics and metrology, focusing on the construction of a standard of length based on the seconds pendulum and the determination of the unit of electrical resistance. It also discusses broader historical issues in physics and metrology, including labour practices in physics, physics pedagogy, long-term processes of modernity (bureaucratization, industrialization, and the construction of empires), and the moral and ethical connotations of standards of measure. It shows that moral values became intertwined with metrology, especially in the British context.
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Частини книг з теми "Length metrology"

1

Flügge, Jens, Stefanie Kroker, and Harald Schnatz. "Fundamental Length Metrology." In Handbook of Laser Technology and Applications, 3–22. 2nd ed. 2nd edition. | Boca Raton : CRC Press, 2021– |: CRC Press, 2021. http://dx.doi.org/10.1201/9781003130123-2.

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2

Hebra, Alexius J. "The measurement of length." In The Physics of Metrology, 1–21. Vienna: Springer Vienna, 2010. http://dx.doi.org/10.1007/978-3-211-78381-8_1.

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3

Nawrocki, Waldemar. "Standards and Measurements of Length." In Introduction to Quantum Metrology, 245–56. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-19677-6_10.

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4

Nawrocki, Waldemar. "Standards and Measurements of Length." In Introduction to Quantum Metrology, 215–36. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15669-9_10.

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5

Jiang, Y., Y. Huang, and K. Gao. "Optical Atomic Clock and Laser Applications to Length and Time Metrology." In Handbook of Laser Technology and Applications, 157–69. 2nd ed. 2nd edition. | Boca Raton : CRC Press, 2021– |: CRC Press, 2021. http://dx.doi.org/10.1201/9781003130123-10.

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6

Softić, Almira, Hazim Bašić, Samir Lemeš, and Nermina Zaimović-Uzunović. "Research of Traceability of Unit of Length in Metrology System of Bosnia and Herzegovina." In Lecture Notes in Mechanical Engineering, 89–97. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-18177-2_9.

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7

"Fundamental length metrology." In Handbook of Laser Technology and Applications (Three- Volume Set), 1692–717. CRC Press, 2003. http://dx.doi.org/10.1201/noe0750309608-92.

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8

"Length Measurement." In Introduction to OPTICAL METROLOGY, 367–403. CRC Press, 2017. http://dx.doi.org/10.1201/9781315215228-14.

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9

"Length Measurement." In Introduction to OPTICAL METROLOGY, 225–44. CRC Press, 2017. http://dx.doi.org/10.1201/9781315215228-6.

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10

Schödel, René. "Length and Size." In Handbook of Optical Metrology. CRC Press, 2009. http://dx.doi.org/10.1201/9781420019513.ch15.

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Тези доповідей конференцій з теми "Length metrology"

1

Potzick, James E. "New certified length scale for microfabrication metrology." In Micromachining and Microfabrication '96, edited by Michael T. Postek, Jr. and Craig R. Friedrich. SPIE, 1996. http://dx.doi.org/10.1117/12.250945.

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2

Chapman, G. D. "Optical Metrology In Length And Mechanical Standards." In 1986 Quebec Symposium, edited by Chander P. Grover. SPIE, 1986. http://dx.doi.org/10.1117/12.938620.

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3

Pi, Jiajing, Li-Zhuan Zhao, Jian-Guo Du, and Wei-Guo Shen. "High-precision laser interferometer for length metrology." In Measurement Technology and Intelligent Instruments, edited by Li Zhu. SPIE, 1993. http://dx.doi.org/10.1117/12.156509.

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4

Zhao, L. P., N. Bai, X. Li, Z. P. Fang, A. A. Hein, and Z. W. Zhong. "Special lenslet array with long focal length range for Shack-Hartmann Wavefront Sensor." In Optical Metrology, edited by Wolfgang Osten, Christophe Gorecki, and Erik L. Novak. SPIE, 2007. http://dx.doi.org/10.1117/12.726043.

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5

Grossman, Erich. "Focus-variation microscopy for measurement of surface roughness and autocorrelation length." In SPIE Optical Metrology, edited by Peter Lehmann, Wolfgang Osten, and Armando Albertazzi Gonçalves. SPIE, 2017. http://dx.doi.org/10.1117/12.2271863.

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6

Abolhassani, Mohammad. "Evaluation of focal length of a lens using the Lau effect." In SPIE Optical Metrology, edited by Peter Lehmann, Wolfgang Osten, and Armando Albertazzi Gonçalves. SPIE, 2015. http://dx.doi.org/10.1117/12.2185088.

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7

Machekhin, Yu P., V. M. Smulakovsky, and A. V. Solovyov. "Primary standard of length unit-meter based on the group of He-Ne/I2 lasers." In Optoelectronic Metrology, edited by Jan Owsik and Tomasz Wiecek. SPIE, 1999. http://dx.doi.org/10.1117/12.373745.

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8

Deliyski, Radoslav. "Virtual Measurement System for Length Measurement Based on Visual-Inertial Odometry." In 2020 XXX International Scientific Symposium 'Metrology and Metrology Assurance (MMA). IEEE, 2020. http://dx.doi.org/10.1109/mma49863.2020.9254258.

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9

Jin, Jonghan, Young-Jin Kim, Yunseok Kim, Sangwon Hyun, and Seung-Woo Kim. "Precision Length Metrology based on Optical Frequency Synthesizer." In 2007 Conference on Lasers and Electro-Optics - Pacific Rim. IEEE, 2007. http://dx.doi.org/10.1109/cleopr.2007.4391293.

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10

Minoshima, Kaoru, and Hajime Inaba. "Precision Length Metrology using Fiber-Based Frequency Combs." In Optical Sensors. Washington, D.C.: OSA, 2010. http://dx.doi.org/10.1364/sensors.2010.stub1.

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