T. Strahl, J. Herbst, Eric Maier, S. Rademacher, C. Weber, H. Pernau, A. Lambrecht, J. Wöllenstein
Abstract. The measurement of low methane ( CH4 ) concentrations is a key objective for safety of industrial and public infrastructures and in environmental research. Laser spectroscopy is best suited for this purpose because it offers high sensitivity, selectivity, dynamic range, and a fast measurement rate. The physical basis of this technique is infrared absorption of molecular gases. Two detection schemes – direct absorption spectroscopy (DAS) and photoacoustic spectroscopy (PAS) – are compared at three wavelength regions in the near-infrared (NIR), mid-wavelength (MWIR), and long-wavelength (LWIR) infrared ranges. For each spectral range a suitable semiconductor laser is selected and used for both detection techniques: a diode laser (DL), an interband cascade laser (ICL), and a quantum cascade laser (QCL) for NIR, MWIR and LWIR, respectively. For DAS short absorption path lengths comparable to the cell dimensions of the photoacoustic cell for PAS are employed. We show that for DAS the lowest detection limit can be achieved in the MWIR range with noise-equivalent concentrations (NECs) below 10 ppb. Using PAS, lower detection limits and higher system stabilities can be reached compared to DAS, especially for long integration times. The lowest detection limit for PAS is obtained in the LWIR with a NEC of 7 ppb. The different DAS and PAS configurations are discussed with respect to potential applications.
{"title":"Comparison of laser-based photoacoustic and optical detection of methane","authors":"T. Strahl, J. Herbst, Eric Maier, S. Rademacher, C. Weber, H. Pernau, A. Lambrecht, J. Wöllenstein","doi":"10.5194/JSSS-10-25-2021","DOIUrl":"https://doi.org/10.5194/JSSS-10-25-2021","url":null,"abstract":"Abstract. The measurement of low methane ( CH4 ) concentrations is a key objective for safety of industrial and public infrastructures and in environmental research. Laser spectroscopy is best suited for this purpose because it offers high sensitivity, selectivity, dynamic range, and a fast measurement rate. The physical basis of this technique is infrared absorption of molecular gases. Two detection schemes – direct absorption spectroscopy (DAS) and photoacoustic spectroscopy (PAS) – are compared at three wavelength regions in the near-infrared (NIR), mid-wavelength (MWIR), and long-wavelength (LWIR) infrared ranges. For each spectral range a suitable semiconductor laser is selected and used for both detection techniques: a diode laser (DL), an interband cascade laser (ICL), and a quantum cascade laser (QCL) for NIR, MWIR and LWIR, respectively. For DAS short absorption path lengths comparable to the cell dimensions of the photoacoustic cell for PAS are employed. We show that for DAS the lowest detection limit can be achieved in the MWIR range with noise-equivalent concentrations (NECs) below 10 ppb. Using PAS, lower detection limits and higher system stabilities can be reached compared to DAS, especially for long integration times. The lowest detection limit for PAS is obtained in the LWIR with a NEC of 7 ppb. The different DAS and PAS configurations are discussed with respect to potential applications.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45573839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Nitsche, M. Franke, N. Haverkamp, D. Heißelmann
Abstract. The estimation of the six-degree-of-freedom position and orientation of an end effector is of high interest in industrial robotics. High precision and data rates are important requirements when choosing an adequate measurement system. In this work, a six-degree-of-freedom pose estimation setup based on laser multilateration is described together with the measurement principle and self-calibration strategies used in this setup. In an experimental setup, data rates of 200 Hz are achieved. During movement, deviations from a reference coordinate measuring machine of 20 µm are observed. During standstill, the deviations are reduced to 5 µm .
{"title":"Six-degree-of-freedom pose estimation with µm/µrad accuracy based on laser multilateration","authors":"J. Nitsche, M. Franke, N. Haverkamp, D. Heißelmann","doi":"10.5194/JSSS-10-19-2021","DOIUrl":"https://doi.org/10.5194/JSSS-10-19-2021","url":null,"abstract":"Abstract. The estimation of the six-degree-of-freedom position and orientation of an end effector is of high interest in industrial robotics. High precision and data rates are important requirements when choosing an adequate measurement system. In this work, a six-degree-of-freedom pose estimation setup based on laser multilateration is described together with the measurement principle and self-calibration strategies used in this setup. In an experimental setup, data rates of 200 Hz are achieved. During movement, deviations from a reference coordinate measuring machine of 20 µm are observed. During standstill, the deviations are reduced to 5 µm .","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45609799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Laser materials processing of workpieces using ultra-short pulsed lasers can lead to unwanted X-ray emission. Their dose rate and spectral distribution have been precisely determined. The measurements were carried out using a thermoluminescence detector (TLD)-based spectrometer in which 30 TLD planes are arranged one behind the other, the first 10 layers made of polymethyl methacrylate, while the remaining 20 layers are interspaced by absorbers with, from the front to the back, increasing atomic charge and thickness. The penetration depth of the radiation into the spectrometer depends on its energy, so that the energy-resolved spectrum of the radiation can be calculated from the TLD dose values by means of mathematical methods (Bayesian deconvolution). The evaluation process also takes into account both the uncertainties of all input quantities and the possibility of adopting different models for the spectrum form. This allowed the resulting spectra to be associated with their realistic uncertainty. The measurements are traceable to the Systeme international d'unites (SI), i.e. the International System of Units. The results not only provide manufacturers and users of ultra-short pulsed lasers with important information on the design of the machines with regard to radiation protection, but were also included in the recently concluded legislative procedure in the field of radiation protection in Germany.
{"title":"Measurements at laser materials processing machines: spectrum deconvolution including uncertainties and model selection","authors":"R. Behrens, B. Pullner, M. Reginatto","doi":"10.5194/JSSS-10-13-2021","DOIUrl":"https://doi.org/10.5194/JSSS-10-13-2021","url":null,"abstract":"Abstract. Laser materials processing of workpieces using ultra-short pulsed lasers can lead to unwanted X-ray emission. Their dose rate and spectral distribution have been precisely determined. The measurements were\u0000carried out using a thermoluminescence detector (TLD)-based spectrometer in which 30 TLD planes are arranged one behind the other, the first 10 layers\u0000made of polymethyl methacrylate, while the remaining 20 layers are interspaced by absorbers with, from the front to the back, increasing atomic\u0000charge and thickness. The penetration depth of the radiation into the\u0000spectrometer depends on its energy, so that the energy-resolved spectrum of\u0000the radiation can be calculated from the TLD dose values by means of\u0000mathematical methods (Bayesian deconvolution). The evaluation process also\u0000takes into account both the uncertainties of all input quantities and the\u0000possibility of adopting different models for the spectrum form. This allowed\u0000the resulting spectra to be associated with their realistic uncertainty. The measurements are traceable to the Systeme international d'unites (SI), i.e. the International System of Units. The results not only provide manufacturers and users of ultra-short pulsed lasers with important information on the design of the machines with regard to radiation\u0000protection, but were also included in the recently concluded legislative procedure in the field of radiation protection in Germany.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47786655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Bernhardsgrütter, C. Hepp, M. Jägle, H. Pernau, K. Schmitt, J. Wöllenstein
Abstract. Because diesel combustion processes produce harmful detrimental nitrous oxides, the selective catalytic reduction, an after-treatment method using diesel exhaust fluid (AdBlue) to reduce these emissions, is an important part in the cycle of the combustion process. Therefore, it is crucial to continuously monitor the quality of the diesel exhaust fluid to secure the ideal selective catalytic reduction. This article presents a platinum thin-film sensor using the 3 ω method which is able to characterize the diesel exhaust fluid. By means of the 3 ω method, information about the concentration of urea in water can be extracted. In this investigation, a digital lock-in amplification technique is used to execute the measurements. The results show that this sensor can determine the urea content within 1 % by weight. Moreover, besides the analysis of the 3 ω signal, the 1 ω signal is analyzed in depth to receive additional information about the temperature. Because the same structure can measure multiple parameters, such as concentration, temperature, and flow, the sensor might be a good alternative to the state-of-the-art diesel exhaust fluid sensor.
{"title":"Inline quality monitoring of diesel exhaust fluid (AdBlue) by using the 3ω method","authors":"R. Bernhardsgrütter, C. Hepp, M. Jägle, H. Pernau, K. Schmitt, J. Wöllenstein","doi":"10.5194/JSSS-10-5-2021","DOIUrl":"https://doi.org/10.5194/JSSS-10-5-2021","url":null,"abstract":"Abstract. Because diesel combustion processes produce harmful detrimental nitrous oxides, the selective catalytic reduction, an after-treatment method using diesel exhaust fluid (AdBlue) to reduce these emissions, is an important part in the cycle of the combustion process. Therefore, it is crucial to continuously monitor the quality of the diesel exhaust fluid to secure the ideal selective catalytic reduction. This article presents a platinum thin-film sensor using the 3 ω method which is able to characterize the diesel exhaust fluid. By means of the 3 ω method, information about the concentration of urea in water can be extracted. In this investigation, a digital lock-in amplification technique is used to execute the measurements. The results show that this sensor can determine the urea content within 1 % by weight. Moreover, besides the analysis of the 3 ω signal, the 1 ω signal is analyzed in depth to receive additional information about the temperature. Because the same structure can measure multiple parameters, such as concentration, temperature, and flow, the sensor might be a good alternative to the state-of-the-art diesel exhaust fluid sensor.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48608944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Different options were discussed before reaching the final agreement on the new definitions of the SI units, effective from 20 May 2019, especially with regard to the kilogram, now defined in terms of the numerical value of the Planck constant ( h ). Replacing the artefact definition of the kilogram with a new one based on the mass of a particle, or the atomic mass constant ( mu ), would have been preferable for ease of understanding, among other reasons. In this paper we discuss some limitations of teaching to different audiences what a kilogram is in the redefined International System of Units (SI), including realizations of the new definition.
{"title":"Explaining to different audiences the new definition and experimental realizations of the kilogram","authors":"J. Valdés","doi":"10.5194/JSSS-10-1-2021","DOIUrl":"https://doi.org/10.5194/JSSS-10-1-2021","url":null,"abstract":"Abstract. Different options were discussed before reaching the final agreement on the new definitions of the SI units, effective from 20 May 2019, especially with regard to the kilogram, now defined in terms of the numerical value of the Planck constant ( h ). Replacing the artefact definition of the kilogram with a new one based on the mass of a particle, or the atomic mass constant ( mu ), would have been preferable for ease of understanding, among other reasons. In this paper we discuss some limitations of teaching to different audiences what a kilogram is in the redefined International System of Units (SI), including realizations of the new definition.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45987514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.5194/jsss-10-219-2021
Martin Lerchen, Jakob Hornung, Yu Zou, T. Hausotte
Abstract. Additive manufacturing technologies are further developing from prototype to serial production. This trend requires rising challenges to the process-accompanying quality assurance. Optical in situ quality control approaches show great potential to generate accurate measurement data, which are essential for feedback control. If a reliable referencing concept for the layer-by-layer measured data is guaranteed, contour information can be used during the manufacturing to correct occurring geometrical deviations. Within this scientific study, two methods of optical, referenced in situ control of lateral displacements of additive manufactured contours are presented. In the first approach the 2-D contour of the melting pool is analysed in relation to a position-stable reference system implemented in the powder bed. The second approach uses the translucent contour of deeper layers covered with powder as a reference. Within the image evaluation several pre-processing steps like calibration, undistortion, rectification, illumination correction and low-pass filtering are essential for reliable and correct geometric measurements. The following adapted contour detection and position determination of the referenced melting pool contours are based on an extended edge detection algorithm according to Canny (1986). With the evaluation of further manufacturing layers of already lowered powder bed levels, it is possible to specify the influence of powder application on geometrical displacements separately. This is done by a comparison of the position of the detected powder-covered melting pool contours with the previously applied melted region. Consequently a better understanding of lateral contour displacements within the additive manufacturing process is the goal, which is important for a process-accompanying correction of geometrical deviations.
{"title":"Methods and procedure of referenced in situ control of lateral contour displacements in additive manufacturing","authors":"Martin Lerchen, Jakob Hornung, Yu Zou, T. Hausotte","doi":"10.5194/jsss-10-219-2021","DOIUrl":"https://doi.org/10.5194/jsss-10-219-2021","url":null,"abstract":"Abstract. Additive manufacturing technologies are further developing from prototype to serial production. This trend requires rising challenges to the process-accompanying quality assurance. Optical in situ quality control approaches show great potential to generate accurate measurement data, which are essential for feedback control. If a reliable referencing concept for the layer-by-layer measured data is guaranteed, contour information can be used during the manufacturing to correct occurring geometrical deviations. Within this scientific study, two methods of optical, referenced in situ control of lateral displacements of additive manufactured contours are presented. In the first approach the 2-D contour of the melting pool is analysed in relation to a position-stable reference system implemented in the powder bed. The second approach uses the translucent contour of deeper layers covered with powder as a reference. Within the image evaluation several pre-processing steps like calibration, undistortion, rectification, illumination correction and low-pass filtering are essential for reliable and correct geometric measurements. The following adapted contour detection and position determination of the referenced melting pool contours are based on an extended edge detection algorithm according to Canny (1986). With the evaluation of further manufacturing layers of already lowered powder bed levels, it is possible to specify the influence of powder application on geometrical displacements separately. This is done by a comparison of the position of the detected powder-covered melting pool contours with the previously applied melted region. Consequently a better understanding of lateral contour displacements within the additive manufacturing process is the goal, which is important for a process-accompanying correction of geometrical deviations.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70626778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.5194/jsss-10-261-2021
T. Binkele, D. Hilbig, M. Essameldin, T. Henning, F. Fleischmann, W. Lang
Abstract. The applications of freeform surfaces in optical components and systems are increasing more and more. Therefore, appropriate measurement techniques are needed to measure these freeform surfaces for verification. This task is still a challenge for most measurement techniques. In this paper, we propose a measurement technique for optical and other specular freeform surfaces based on experimental ray tracing. This technique is able to measure form and mid-spatial-frequency deviations simultaneously. The focus will be set on the sensing technique and the measurement uncertainties in the setup. As the measurement technique is described, an estimation of the influence of different uncertainties based on simulations is given. The result from an experimental measurement is evaluated in relation to the influence of the uncertainties. A comparison measurement for evaluation is given.
{"title":"Characterization of specular freeform surfaces from reflected ray directions using experimental ray tracing","authors":"T. Binkele, D. Hilbig, M. Essameldin, T. Henning, F. Fleischmann, W. Lang","doi":"10.5194/jsss-10-261-2021","DOIUrl":"https://doi.org/10.5194/jsss-10-261-2021","url":null,"abstract":"Abstract. The applications of freeform surfaces in optical components and systems are increasing more and more. Therefore, appropriate measurement techniques are needed to measure these freeform surfaces for verification. This task is still a challenge for most measurement techniques. In this paper, we propose a measurement technique for optical and other specular freeform surfaces based on experimental ray tracing. This technique is able to measure form and mid-spatial-frequency deviations simultaneously. The focus will be set on the sensing technique and the measurement uncertainties in the setup. As the measurement technique is described, an estimation of the influence of different uncertainties based on simulations is given. The result from an experimental measurement is evaluated in relation to the influence of the uncertainties. A comparison measurement for evaluation is given.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70626429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.5194/jsss-10-193-2021
Q. Zaman, S. Alraho, A. König
Abstract. This paper aims to improve the traditional calibration method for reconfigurable self-X (self-calibration, self-healing, self-optimize, etc.) sensor interface readout circuit for industry 4.0. A cost-effective test stimulus is applied to the device under test, and the transient response of the system is analyzed to correlate the circuit's characteristics parameters. Due to complexity in the search and objective space of the smart sensory electronics, a novel experience replay particle swarm optimization (ERPSO) algorithm is being proposed and proved a better-searching capability than some currently well-known PSO algorithms. The newly proposed ERPSO expanded the selection producer of the classical PSO by introducing an experience replay buffer (ERB) intending to reduce the probability of trapping into the local minima. The ERB reflects the archive of previously visited global best particles, while its selection is based upon an adaptive epsilon greedy method in the velocity updating model. The performance of the proposed ERPSO algorithm is verified by using eight different popular benchmarking functions. Furthermore, an extrinsic evaluation of the ERPSO algorithm is also examined on a reconfigurable wide swing indirect current-feedback instrumentation amplifier (CFIA). For the later test, we proposed an efficient optimization procedure by using total harmonic distortion analyses of CFIA output to reduce the total number of measurements and save considerable optimization time and cost. The proposed optimization methodology is roughly 3 times faster than the classical optimization process. The circuit is implemented by using Cadence design tools and CMOS 0.35 µm technology from Austria Microsystems (AMS). The efficiency and robustness are the key features of the proposed methodology toward implementing reliable sensory electronic systems for industry 4.0 applications.
{"title":"Efficient transient testing procedure using a novel experience replay particle swarm optimizer for THD-based robust design and optimization of self-X sensory electronics in industry 4.0","authors":"Q. Zaman, S. Alraho, A. König","doi":"10.5194/jsss-10-193-2021","DOIUrl":"https://doi.org/10.5194/jsss-10-193-2021","url":null,"abstract":"Abstract. This paper aims to improve the traditional calibration method for reconfigurable self-X (self-calibration, self-healing, self-optimize, etc.) sensor interface readout circuit for industry 4.0. A cost-effective test stimulus is applied to the device under test, and the transient response of the system is analyzed to correlate the circuit's characteristics parameters. Due to complexity in the search and objective space of the smart sensory electronics, a novel experience replay particle swarm optimization (ERPSO) algorithm is being proposed and proved a better-searching capability than some currently well-known PSO algorithms. The newly proposed ERPSO expanded the selection producer of the classical PSO by introducing an experience replay buffer (ERB) intending to reduce the probability of trapping into the local minima. The ERB reflects the archive of previously visited global best particles, while its selection is based upon an adaptive epsilon greedy method in the velocity updating model. The performance of the proposed ERPSO algorithm is verified by using eight different popular benchmarking functions. Furthermore, an extrinsic evaluation of the ERPSO algorithm is also examined on a reconfigurable wide swing indirect current-feedback instrumentation amplifier (CFIA). For the later test, we proposed an efficient optimization procedure by using total harmonic distortion analyses of CFIA output to reduce the total number of measurements and save considerable optimization time and cost. The proposed optimization methodology is roughly 3 times faster than the classical optimization process. The circuit is implemented by using Cadence design tools and CMOS 0.35 µm technology from Austria Microsystems (AMS). The efficiency and robustness are the key features of the proposed methodology toward implementing reliable sensory electronic systems for industry 4.0 applications.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70626867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.5194/jsss-10-207-2021
S. Schramm, J. Ebert, J. Rangel, R. Schmoll, A. Kroll
Abstract. The geometric calibration of cameras becomes necessary when images should be undistorted, geometric image information is needed or data from more than one camera have to be fused. This process is often done using a target with a checkerboard or circular pattern and a given geometry. In this work, a coded checkerboard target for thermal imaging cameras and the corresponding image processing algorithm for iterative feature detection are presented. It is shown that, due in particular to the resulting better feature detectability at image borders, lower uncertainties in the estimation of the distortion parameters are achieved.
{"title":"Iterative feature detection of a coded checkerboard target for the geometric calibration of infrared cameras","authors":"S. Schramm, J. Ebert, J. Rangel, R. Schmoll, A. Kroll","doi":"10.5194/jsss-10-207-2021","DOIUrl":"https://doi.org/10.5194/jsss-10-207-2021","url":null,"abstract":"Abstract. The geometric calibration of cameras becomes necessary when images should be undistorted, geometric image information is needed or data from more than one camera have to be fused. This process is often done using a target with a checkerboard or circular pattern and a given geometry. In this work, a coded checkerboard target for thermal imaging cameras and the corresponding image processing algorithm for iterative feature detection are presented. It is shown that, due in particular to the resulting better feature detectability at image borders, lower uncertainties in the estimation of the distortion parameters are achieved.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70626766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. We present the metrological characterization and calibration of three different types of thermographic cameras for quantitative temperature measurement traceable to the International Temperature Scale (ITS-90). Relevant technical specifications – i.e., the non-uniformity of the pixel-to-pixel responsivity, the inhomogeneity equivalent temperature difference (IETD), the noise equivalent temperature difference (NETD), and the size-of-source effect (SSE) – are determined according to the requirements given in the series of Technical Directives VDI/VDE 5585. The measurements are performed with the camera calibration facility of the Physikalisch-Technische Bundesanstalt. The data reference method is applied for the determination and improvement of the non-uniformity, leading to an improved IETD for all three cameras. Finally, the cameras are calibrated according to the different procedures discussed in the VDI/VDE 5585 series. Results achieved with the different calibration procedures are compared for each type of camera and among the three cameras. An uncertainty budget for the calibration of each camera is given according to GUM (ISO, 1995) and VDI/VDE 5585.
{"title":"Metrological characterization and calibration of thermographic cameras for quantitative temperature measurement","authors":"S. König, B. Gutschwager, R. Taubert, J. Hollandt","doi":"10.5194/jsss-9-425-2020","DOIUrl":"https://doi.org/10.5194/jsss-9-425-2020","url":null,"abstract":"Abstract. We present the metrological characterization and calibration of three different types of thermographic cameras for quantitative temperature\u0000measurement traceable to the International Temperature Scale (ITS-90). Relevant technical specifications – i.e., the non-uniformity of the pixel-to-pixel responsivity, the inhomogeneity equivalent temperature difference (IETD), the noise equivalent temperature difference (NETD), and the size-of-source effect (SSE) – are determined according to the requirements given in the series of Technical Directives VDI/VDE 5585. The\u0000measurements are performed with the camera calibration facility of the Physikalisch-Technische Bundesanstalt. The data reference method is applied for the determination and improvement of the non-uniformity, leading to an improved IETD for all three cameras. Finally, the cameras are calibrated\u0000according to the different procedures discussed in the VDI/VDE 5585 series. Results achieved with the different calibration procedures are compared\u0000for each type of camera and among the three cameras. An uncertainty budget for the calibration of each camera is given according to GUM (ISO, 1995)\u0000and VDI/VDE 5585.\u0000","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46609661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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