scholarly journals Gear Shape Measurement Potential of Laser Triangulation and Confocal-Chromatic Distance Sensors

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 937
Author(s):  
Marc Pillarz ◽  
Axel von Freyberg ◽  
Dirk Stöbener ◽  
Andreas Fischer
Keyword(s):  
Measurement Uncertainty ◽  
Surface Properties ◽  
Optical Sensors ◽  
Laser Triangulation ◽  
Shape Measurement ◽  
Full Potential ◽  
Position Measurement ◽  
Standard Measurement ◽  
Measurement Systems ◽  
Measurement Approach

The demand for extensive gear shape measurements with single-digit µm uncertainty is growing. Tactile standard gear tests are precise but limited in speed. Recently, faster optical gear shape measurement systems have been examined. Optical gear shape measurements are challenging due to potential deviation sources such as the tilt angles between the surface normal and the sensor axis, the varying surface curvature, and the surface properties. Currently, the full potential of optical gear shape measurement systems is not known. Therefore, laser triangulation and confocal-chromatic gear shape measurements using a lateral scanning position measurement approach are studied. As a result of tooth flank standard measurements, random effects due to surface properties are identified to primarily dominate the achievable gear shape measurement uncertainty. The standard measurement uncertainty with the studied triangulation sensor amounts to >10 µm, which does not meet the requirements. The standard measurement uncertainty with the confocal-chromatic sensor is <6.5 µm. Furthermore, measurements on a spur gear show that multiple reflections do not influence the measurement uncertainty when measuring with the lateral scanning position measurement approach. Although commercial optical sensors are not designed for optical gear shape measurements, standard uncertainties of <10 µm are achievable for example with the applied confocal-chromatic sensor, which indicates the further potential for optical gear shape measurements.

Measurement Uncertainty of Microscopic Laser Triangulation on Technical Surfaces

2015 ◽  
Vol 21 (6) ◽  
pp. 1443-1454 ◽  
Author(s):  
Thomas Mueller ◽  
Andreas Poesch ◽  
Eduard Reithmeier
Keyword(s):  
Surface Roughness ◽  
Measurement Uncertainty ◽  
Surface Properties ◽  
Three Dimensional ◽  
Laser Speckle ◽  
Dimensional Structure ◽  
Laser Triangulation ◽  
Surface Measurements ◽  
Microscopic Measurement ◽  
Microscopic Surface

AbstractLaser triangulation is widely used to measure three-dimensional structure of surfaces. The technique is suitable for macroscopic and microscopic surface measurements. In this paper, the measurement uncertainty of laser triangulation is investigated on technical surfaces for microscopic measurement applications. Properties of technical surfaces are, for example, reflectivity, surface roughness, and the presence of scratches and pores. These properties are more influential in the microscopic laser triangulation than in the macroscopic one. In the Introduction section of this paper, the measurement uncertainty of laser triangulation is experimentally investigated for 13 different specimens. The measurements were carried out with and without a laser speckle reducer. In the Materials and Methods section of this paper, the surfaces of the 13 specimens are characterized in order to be able to find correlations between the surface properties and the measurement uncertainty. The last section of this paper describes simulations of the measurement uncertainty, which allow for the calculation of the measurement uncertainty with only one source of uncertainty present. The considerations in this paper allow for the assessment of the measurement uncertainty of laser triangulation on any technical surface when some surface properties, such as roughness, are known.

scholarly journals Modeling the unified measurement uncertainty of deflectometric and plenoptic 3-D sensors

2018 ◽  
Vol 7 (2) ◽  
pp. 517-533
Author(s):  
Mathias Ziebarth ◽  
Niclas Zeller ◽  
Michael Heizmann ◽  
Franz Quint
Keyword(s):  
Measurement Uncertainty ◽  
Surface Properties ◽  
Optical Sensors ◽  
Sensor System ◽  
Ambient Light ◽  
New Models ◽  
Measurement Uncertainties ◽  
Reflecting Surfaces ◽  
Combined Sensor ◽  
Specular Surfaces

Abstract. In this paper we propose new models of two complementary optical sensors to obtain 2.5-D measurements of opaque surfaces: a deflectometric and a plenoptic sensor. The deflectometric sensor uses active triangulation and works best on specular surfaces, while the plenoptic sensor uses passive triangulation and works best on textured, diffusely reflecting surfaces. We propose models to describe the measurement uncertainties of the sensors for specularly to diffusely reflecting surfaces under consideration of typical disturbances like ambient light or vibration. The predicted measurement uncertainties of both sensors can be used to obtain optimized measurements uncertainties for varying surface properties on the basis of a combined sensor system. The models are validated exemplarily based on real measurements.

Measurement uncertainty of non-incremental, non-contact, in-situ shape measurements

2017 ◽  
Vol 84 (6) ◽  
Author(s):  
Micha Sebastian Schuster ◽  
Robert Kuschmierz ◽  
Jürgen Czarske
Keyword(s):  
Measurement Uncertainty ◽  
Optical Measurement ◽  
Distance Measurement ◽  
Shape Measurement ◽  
Measurement Systems ◽  
Sensor Position ◽  
The Mean ◽  
Fast Rotating ◽  
Rotating Objects

AbstractOptical measurement systems work fast and non-contact and can achieve sub-micron precision. Thus they appear to be well suited for in-situ shape measurement of fast rotating objects such as cutting processes in metal working lathes. Most optical measurement systems, however, allow an axial position measurement only. In order to retrieve the shape of the object from a distance measurement, the distance between the sensor and the centre of the object has to be known. Otherwise, deviations of this distance, for instance due to temperature effects or vibrations, will result in a measurement deviation. In order to allow an absolute shape measurement, which is independent of the sensor position, the mean radius of the rotating object can be retrieved from the object's circumferential velocity. The laser Doppler distance sensor with phase evaluation (P-LDD sensor) allows a simultaneous velocity and distance measurement with high temporal resolution. Thus, the P-LDD sensor allows to measure the mean radius as well as the spatially resolved deviation of the radius independently of the sensor position. In order to quantify the achievable measurement uncertainty, and especially the influence of the temperature the measurement uncertainty budget is derived and considers random as well as systematic errors. It is shown that the P-LDD sensor allows an absolute, three-dimensional shape measurement of fast rotating objects with sub-micron uncertainty. The systematic measurement uncertainty of the absolute shape due to the temperature amounts to only 200 nm/K. Thus the P-LDD sensor is not dependent on temperature-controlled laboratories but can be employed directly in the production process (in-situ or in-process).

scholarly journals Limiting Uncertainty Relations in Laser-Based Measurements of Position and Velocity Due to Quantum Shot Noise

Entropy ◽  
2019 ◽  
Vol 21 (3) ◽  
pp. 264 ◽  
Author(s):  
Andreas Fischer
Keyword(s):  
Measurement Uncertainty ◽  
Wave Vector ◽  
Shot Noise ◽  
Measurement Techniques ◽  
Time Of Flight ◽  
Wave Number ◽  
Uncertainty Relations ◽  
Position Measurement ◽  
Information Theoretic ◽  
Measurement Systems

With the ongoing progress of optoelectronic components, laser-based measurement systems allow measurements of position as well as displacement, strain and velocity with unbeatable speed and low measurement uncertainty. The performance limit is often studied for a single measurement setup, but a fundamental comparison of different measurement principles with respect to the ultimate limit due to quantum shot noise is rare. For this purpose, the Cramér-Rao bound is described as a universal information theoretic tool to calculate the minimal achievable measurement uncertainty for different measurement techniques, and a review of the respective lower bounds for laser-based measurements of position, displacement, strain and velocity at particles and surfaces is presented. As a result, the calculated Cramér-Rao bounds of different measurement principles have similar forms for each measurand including an indirect proportionality with respect to the number of photons and, in case of the position measurement for instance, the wave number squared. Furthermore, an uncertainty principle between the position uncertainty and the wave vector uncertainty was identified, i.e., the measurement uncertainty is minimized by maximizing the wave vector uncertainty. Additionally, physically complementary measurement approaches such as interferometry and time-of-flight positions measurements as well as time-of-flight and Doppler particle velocity measurements are shown to attain the same fundamental limit. Since most of the laser-based measurements perform similar with respect to the quantum shot noise, the realized measurement systems behave differently only due to the available optoelectronic components for the concrete measurement task.

scholarly journals Analysis of Modern Optical Inspection Systems for Parts Manufactured by Selective Laser Melting

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3202
Author(s):  
Sara Giganto ◽  
Susana Martínez-Pellitero ◽  
Eduardo Cuesta ◽  
Víctor M. Meana ◽  
Joaquín Barreiro
Keyword(s):  
Selective Laser Melting ◽  
Optical Measurement ◽  
Point Of View ◽  
Laser Triangulation ◽  
Laser Melting ◽  
Measurement Systems ◽  
Geometric Dimensioning And Tolerancing ◽  
Inspection Systems ◽  
Conoscopic Holography ◽  
T Values

Metal additive manufacturing (AM) allows obtaining functional parts with the possibility of optimizing them topologically without affecting system performance. This is of great interest for sectors such as aerospace, automotive, and medical–surgical. However, from a metrological point of view, the high requirements applied in these sectors constitute a challenge for inspecting these types of parts. Non-contact inspection has gained great relevance due to the rapid verification of AM parts. Optical measurement systems (OMSs) are being increasingly adopted for geometric dimensioning and tolerancing (GD&T) verification within the context of Industry 4.0. In this paper, the suitability (advantages and limitations) of five different OMSs (based on laser triangulation, conoscopic holography, and structured light techniques) for GD&T verification of parts manufactured by selective laser melting (SLM) is analyzed. For this purpose, a specific testing part was designed and SLM-manufactured in 17-4PH stainless steel. Once the part was measured by contact (obtaining the reference GD&T values), it was optically measured. The scanning results allow comparing the OMSs in terms of their inspection speed as well as dimensional and geometrical accuracy. As a result, two portable systems (handheld laser triangulation and structured blue-light scanners) were identified as the most accurate optical techniques for scanning SLM parts.

scholarly journals Influence of PDA Coating on the Structural, Optical and Surface Properties of ZnO Nanostructures

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2438 ◽  
Author(s):  
Daina Damberga ◽  
Viktoriia Fedorenko ◽  
Kārlis Grundšteins ◽  
Şahin Altundal ◽  
Andris Šutka ◽  
...  
Keyword(s):  
Optical Properties ◽  
Surface Properties ◽  
Optical Sensors ◽  
Zno Nanostructures ◽  
Sensor Applications ◽  
Fundamental Properties ◽  
Model Molecule ◽  
Wide Range ◽  
Pl Quenching

Polydopamine (PDA) is a new biocompatible material, which has prospects in biomedical and sensor applications. Due to functional groups, it can host wide range of biomolecules. ZnO nanostructures are well known templates for optical sensors and biosensors. The combination of ZnO and PDA results in a change of optical properties of ZnO–PDA composites as a shift of photoluminescence (PL) peaks and PL quenching. However, to date, the effect of the PDA layer on fundamental properties of ZnO–PDA nanostructures has not been studied. The presented paper reports on optical and surface properties of novel ZnO–PDA nanocomposites. PDA layers were chemically synthesized on ZnO nanostructures from different solution concentrations of 0.3, 0.4, 0.5 and 0.7 mg/mL. Structure, electronic and optical properties were studied by SEM, Raman, FTIR, diffuse reflectance and photoluminescence methods. The Z-potential of the samples was evaluated in neutral pH (pH = 7.2). The response of the samples towards poly-l-lysine adsorption, as a model molecule, was studied by PL spectroscopy to evaluate the correlation between optical and surface properties. The role of the PDA concentration on fundamental properties was discussed.

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