Metrological characterization of optical confocal sensors measurements (20 and 350 travel ranges)

Nouira, Hichem; El-Hayek, N.; Yuan, Xue Rui; Anwer, Nabil; Salgado, José Manuel

doi:10.1088/1742-6596/483/1/012015

Cited by 9 publications

(8 citation statements)

References 6 publications

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“…This value is considered to be too large because the measurement precision is requested to be within few tens of nanometers. Based on this result and the works of Leach and Nouira et al, 11,27,28 the behavior of the chromatic confocal probe seems to be complex and sensitive to many parameters, particularly, gap variations (residual errors and linearity), material, roughness, form, reflectivity and inclination of the workpiece, power of the light source, acquisition frequency and scanning speed.…”

Section: Chromatic Confocal Probementioning

confidence: 53%

Comparison of tactile and chromatic confocal measurements of aspherical lenses for form metrology

Nadim

Nouira

Anwer

et al. 2014

Int. J. Precis. Eng. Manuf.

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Both contact and non-contact probes are often used in dimensional metrology applications, especially for roughness, form and surface profile measurements. To perform such kind of measurements with a nanometer level of accuracy, LNE (French National Metrology Institute (NMI)) has developed a high precision profilometer traceable to the SI meter definition. The architecture of the machine contains a short and stable metrology frame dissociated from the supporting frame. It perfectly respects Abbe principle. The metrology loop incorporates three Renishaw laser interferometers and is equipped either with a chromatic confocal probe or a tactile probe to achieve measurements at the nanometric level of uncertainty. The machine allows the in-situ calibration of the probes by means of a differential laser interferometer considered as a reference. In this paper, both the architecture and the operation of the LNE's high precision profilometer are detailed. A brief comparison of the behavior of the chromatic confocal and tactile probes is presented. Optical and tactile scans of an aspherical surface are performed and the large number of data are processed using the L-BFGS (Limited memory-Broyden-Fletcher-Goldfarb-Shanno) algorithm. Fitting results are compared with respect to the evaluated residual errors which reflect the form defects of the surface

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Section: Chromatic Confocal Probementioning

confidence: 53%

Comparison of tactile and chromatic confocal measurements of aspherical lenses for form metrology

Nadim

Nouira

Anwer

et al. 2014

Int. J. Precis. Eng. Manuf.

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“…Yang et al [26] reviewed a range of 3D surface measurement methods and determined that confocal laser measurement (CLM) is a suitable method for microscale surface characterization with high axial resolution and high signal-to-noise ratio. Nouira et al [27] studied confocal sensor behavior with respect to surface material and errors, which ensures the reliability of these types of sensors.…”

Section: Introductionmentioning

confidence: 99%

An Automatic, Contactless, High-Precision, High-Speed Measurement System to Provide In-Line, As-Molded Three-Dimensional Measurements of a Curved-Shape Injection-Molded Part

et al. 2022

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In the manufacturing of injection-molded plastic parts, it is essential to perform a non-destructive (and, in some applications, contactless) three-dimensional measurement and surface inspection of the injection-molded part to monitor the part quality. The measurement method depends strongly on the shape and the optical properties of the part. In this study, a high-precision (±5 µm) and high-speed system (total of 24 s for a complete part dimensional measurement) was developed to measure the dimensions of a piano-black injection-molded part. This measurement should be done in real time and close to the part’s production time to evaluate the quality of the produced parts for future online, closed-loop, and predictive quality control. Therefore, a novel contactless, three-dimensional measurement system using a multicolor confocal sensor was designed and manufactured, taking into account the nominal curved shape and the glossy black surface properties of the part. This system includes one linear and one cylindrical moving axis, as well as one confocal optical sensor for radial R-direction measurements. A 6 DOF (degrees of freedom) robot handles the part between the injection molding machine and the measurement system. An IPC coordinates the communications and system movements over the OPC UA communication network protocol. For validation, several repeatability tests were performed at various speeds and directions. The results were compared using signal similarity methods, such as MSE, SSID, and RMS difference. The repeatability of the system in all directions was found to be in the range of ±5 µm for the desired speed range (less than 60 mm/s–60 degrees/s). However, the error increases up to ±10 µm due to the fixture and the suction force effect.

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“…It is worth mentioning that some works have been carried out on characterization of metrological characteristics defined in ISO 25178-600 [22], such as amplification coefficient, linearity deviation, x-y perpendicularity deviation, etc. [23][24][25][26]. These metrological characteristics imply the whole instrumentation system's characteristics to some extent.…”

Section: Introductionmentioning

confidence: 99%

Characterization and Correction of the Geometric Errors in Using Confocal Microscope for Extended Topography Measurement. Part I: Models, Algorithms Development and Validation

Wang

Gómez

2019

Electronics

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This work presents a method for characterizing and correcting the geometric errors of the movement of the lateral stage of Imaging Confocal Microscope (CM) in extended topography measurement. For an extended topography measurement, a defined number of 2D images are taken and stitched by correlation methods. Inaccuracies due to linear displacement, vertical and horizontal straightness errors, angular errors, and squareness errors based on the assumption of the rigid body kinematics are described. A mathematical model for the scale calibration of the X- and Y- coordinates is derived according to the system kinematics, the axis chain vector of CM, and the geometric error functions and their approximations by Legendre polynomials. The correction coefficients of the kinematic modelling are determined by the measured and certified data of a dot grid target standard artefact. To process the measurement data, algorithms for data partitions, fittings of cylinder centers, and determinations of coefficients are developed and validated. During which methods such as form removal, K-means clustering, linear and non-linear Least Squares are implemented. Results of the correction coefficients are presented in Part II based on the experimental studies. The mean residual reduces 29.6% after the correction of the lateral stage errors.

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Metrological characterization of optical confocal sensors measurements (20 and 350 travel ranges)

Cited by 9 publications

References 6 publications

Comparison of tactile and chromatic confocal measurements of aspherical lenses for form metrology

Comparison of tactile and chromatic confocal measurements of aspherical lenses for form metrology

An Automatic, Contactless, High-Precision, High-Speed Measurement System to Provide In-Line, As-Molded Three-Dimensional Measurements of a Curved-Shape Injection-Molded Part

Characterization and Correction of the Geometric Errors in Using Confocal Microscope for Extended Topography Measurement. Part I: Models, Algorithms Development and Validation

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