Journal articles: 'Calibration transfer method'

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Blanco, Marcelo, Jordi Coello, Hortensia Iturriaga, Santiago Maspoch, and Esther Rovira. "Wavelength Calibration Transfer between Diode Array UV-Visible Spectrophotometers." Applied Spectroscopy 49, no. 5 (May 1995): 593–97. http://dx.doi.org/10.1366/0003702953964084.

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The need to obtain expeditious results in control analyses of complex mixtures has turned multivariate calibration procedures into major choices for routine analyses. The inherent complexity of the calibration process and the practical need for analyses to be carried out as near the manufacturing line as possible occasionally entail calibrating with a different instrument from that subsequently employed for the analytical measurements proper. This paper exposes the problems potentially arising in transferring calibrations between diode array UV-Vis spectrophotometers. Basically, such problems originate in wavelength differences between spectrophotometers, even if they meet the manufacturer's specifications and the pharmacopoeia recommendations. We developed a straightforward method for harmonizing instrumental responses on the basis of reference wavelengths corresponding to zero values in the first-derivative spectra for potassium dichromate and benzoic acid standards. The method was applied to the analysis of binary mixtures of theophylline and doxylamine by multiple linear and partial least-squares regression with the use of one spectrophotometer for calibration and four others for analyses.

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Guenard, Robert D., Christine M. Wehlburg, Randy J. Pell, and David M. Haaland. "Importance of Prediction Outlier Diagnostics in Determining a Successful Inter-Vendor Multivariate Calibration Model Transfer." Applied Spectroscopy 61, no. 7 (July 2007): 747–54. http://dx.doi.org/10.1366/000370207781393280.

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This paper reports on the transfer of calibration models between Fourier transform near-infrared (FT-NIR) instruments from four different manufacturers. The piecewise direct standardization (PDS) method is compared with the new hybrid calibration method known as prediction augmented classical least squares/partial least squares (PACLS/PLS). The success of a calibration transfer experiment is judged by prediction error and by the number of samples that are flagged as outliers that would not have been flagged as such if a complete recalibration were performed. Prediction results must be acceptable and the outlier diagnostics capabilities must be preserved for the transfer to be deemed successful. Previous studies have measured the success of a calibration transfer method by comparing only the prediction performance (e.g., the root mean square error of prediction, RMSEP). However, our study emphasizes the need to consider outlier detection performance as well. As our study illustrates, the RMSEP values for a calibration transfer can be within acceptable range; however, statistical analysis of the spectral residuals can show that differences in outlier performance can vary significantly between competing transfer methods. There was no statistically significant difference in the prediction error between the PDS and PACLS/PLS methods when the same subset sample selection method was used for both methods. However, the PACLS/PLS method was better at preserving the outlier detection capabilities and therefore was judged to have performed better than the PDS algorithm when transferring calibrations with the use of a subset of samples to define the transfer function. The method of sample subset selection was found to make a significant difference in the calibration transfer results using the PDS algorithm, while the transfer results were less sensitive to subset selection when the PACLS/PLS method was used.

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Zarzhetskaya, Natalya, and Vladimir Litovchenko. "COAXIAL CONTACT DEVICE AND METHOD OF CALIBRATION." Interexpo GEO-Siberia 9 (2019): 77–86. http://dx.doi.org/10.33764/2618-981x-2019-9-77-86.

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A coaxial contact device for connection to the microwave transition analyzer is proposed as coaxial measures for calibrating the analyzer, and the investigated strip line junctions for measuring their S-parameters. In addition, a method for calibrating this device with one or two calculated coaxial-to-stripline calibrators, providing the transfer of the results of calibration of the analyzer by coaxial measures to the measurement of S-parameters of the strip line junctions is presented.

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Bateman, Vesta I., William B. Leisher, Fred A. Brown, and Neil T. Davie. "Calibration of a Hopkinson Bar with a Transfer Standard." Shock and Vibration 1, no. 2 (1993): 145–52. http://dx.doi.org/10.1155/1993/354290.

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A program requirement for field test temperatures that are beyond the test accelerometer operational limits of −30° F and +150° F required the calibration of accelerometers at high shock levels and at the temperature extremes of −50° F and +160° F. The purposes of these calibrations were to insure that the accelerometers operated at the field test temperatures and to provide an accelerometer sensitivity at each test temperature. Because there is no National Institute of Standards and Technology traceable calibration capability at shock levels of 5,000–15,000 g for the temperature extremes of −50° F and +160° F, a method for calibrating and certifying the Hopkinson bar with a transfer standard was developed. Time domain and frequency domain results are given that characterize the Hopkinson bar. The National Institute of Standards and Technology traceable accuracy for the standard accelerometer in shock is ±5%. The Hopkinson bar has been certified with an uncertainty of 6%.

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Borell, G. J., and T. E. Diller. "A Convection Calibration Method for Local Heat Flux Gages." Journal of Heat Transfer 109, no. 1 (February 1, 1987): 83–89. http://dx.doi.org/10.1115/1.3248073.

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An apparatus for calibrating local heat flux gages in convective air flows is described. Heat transfer from a “hot” gage to a “cold” fluid was measured using a guarded hot-plate technique. The system was used to calibrate Gardon-type circular foil heat flux gages of 1/8 in. and 1/16 in. outer diameters. The results indicate that the calibration curves are nonlinear, which is different from the linear calibration obtained using the standard radiation technique. The degree of nonlinearity matches the analysis which accounts for the effect of the temperature distribution in the gage foil. The effect of this temperature distribution can be neglected in the standard radiation calibration but is often significant in convection applications. These results emphasize the importance of calibrating heat flux gages in thermal environments similar to those in which they will be used.

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Wehlburg, Christine M., David M. Haaland, and David K. Melgaard. "New Hybrid Algorithm for Transferring Multivariate Quantitative Calibrations of Intra-Vendor Near-Infrared Spectrometers." Applied Spectroscopy 56, no. 7 (July 2002): 877–86. http://dx.doi.org/10.1366/000370202760171554.

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A new prediction-augmented classical least-squares/partial least-squares (PACLS/PLS) hybrid algorithm is ideally suited for use in transferring multivariate calibrations between spectrometers. Spectral variations such as instrument response differences can be explicitly incorporated into the algorithm through the use of subset sample spectra collected on both spectrometers. Two current calibration transfer methods, subset recalibration and piecewise direct standardization (PDS), also utilize subset sample spectra to facilitate transfer of calibration. The three methods were applied to the transfer of quantitative multivariate calibration models for near-infrared (NIR) data of organic samples containing chlorobenzene, heptane, and toluene between a primary and three secondary spectrometers that were all the same model, called intra-vendor transfer of calibration. The hybrid PACLS/PLS method outperformed subset recalibration and provided predictions equivalent to PDS with additive background correction on the two secondary spectrometers whose instrument drift appeared to be dominated by simple linear baseline variations. One of the secondary spectrometers had complex instrument drift that was captured by repeatedly measuring the spectrum of a single repeat sample. In calculating a transfer function to correct prediction spectra, PDS assumes no instrumental drift on the secondary spectrometer. Therefore, PDS was unable to directly accommodate both the subset samples and the use of a single repeat sample to transfer and maintain a calibration on that secondary instrument. In order to implement the transfer of calibration with PDS in the presence of complex instrument drift, recalibrated PLS models that included the repeat spectra from the secondary spectrometer were used to predict the spectra transformed by PDS. The importance of correcting for drift on the secondary spectrometer during calibration transfer was illustrated by the improvements in prediction for all three methods vs. using only the instrument response differences derived from the subset sample spectra. When the effects of instrument drift were complex on the secondary spectrometer, the PACLS/PLS hybrid algorithm outperformed both PDS and subset recalibration. Through the explicit incorporation of spectral variations, due to instrument response differences and drift on the secondary spectrometer, the PACLS/PLS algorithm was successful at intra-vendor transfer of calibrations between NIR spectrometers.

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Piróg, Przemysław, and Mariusz Górecki. "AC/DC transfer standards calibration in Central Military Calibration Laboratory." Bulletin of the Military University of Technology 66, no. 4 (December 31, 2017): 217–28. http://dx.doi.org/10.5604/01.3001.0010.8333.

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The article discusses the method used in the Central Military Calibration Laboratory to calibrate Fluke 5790 AC/DC transfer standard with reference transfer standard Fluke 792A. It presents the measurement equation and the uncertainty budget. The contribution of uncertainty components in the measurement uncertainty has been presented. The metrological traceability has been evaluated by comparing calibration results with the results in the last Fluke certificate of calibration. Keywords: AC/DC converters, AC/DC difference, thermal voltage converters (TVCs), AC voltage measurement.

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Chen, Aobei, Dapeng Li, Dezhi Zheng, Zhongxiang Li, and Rui Na. "A Fast Calibration Method for Sensors of Atmospheric Detection System." Applied Sciences 12, no. 22 (November 18, 2022): 11733. http://dx.doi.org/10.3390/app122211733.

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To meet the needs of a large number of high-altitude meteorological detections, we need to perform fast, high-precision, and high-reliability calibrations of the sensors in the atmospheric detection system (ADS). However, using the traditional method to calibrate the sensor with high precision often takes a lot of time and increases the cost of workforce and material resources. Therefore, a method for realizing fast sensor calibration under the current system hardware conditions is required. A physical field model of Tube–Air–ADS is proposed for the first time, and the transfer function is obtained by combining the system identification, which provides the possibility for dynamic analysis of the calibration system. A Multi-Criteria Adaptive (MCA) PID controller design method is proposed, which provides a new idea for the parameter design of the controller. It controls the amplitude and switching frequency of the controller’s output signal, ensuring the safe and stable operation of the calibration system. Combined with the hardware parameters of the system, we propose the Variable Precision Steady-State Discrimination (VPSSD) method, which can further shorten the calibration time. Comparing and analyzing the current simulation results under Matlab/Simulink, the proposed MCA method, compared with other PID controller design methods, ensures the stable operation of the calibration system. At the same time, compared with the original system, the calibration time is shortened to 47.7%. Combined with the VPSSD method, the calibration time further shortens to 38.7 s.

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Drennen, Jim. "Calibration Transfer: A Critical Component of Analytical Method Validation." NIR news 14, no. 5 (October 2003): 14–15. http://dx.doi.org/10.1255/nirn.736.

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Li, Xue-Ying, Guo-xing Ren, Ping-Ping Fan, Yan Liu, Zhong-Liang Sun, Guang-Li Hou, and Mei-Rong Lv. "Study on the Calibration Transfer of Soil Nutrient Concentration from the Hyperspectral Camera to the Normal Spectrometer." Journal of Spectroscopy 2020 (April 27, 2020): 1–10. http://dx.doi.org/10.1155/2020/8137142.

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The calibration transfer between instruments is mainly aimed at the calibration transfer between normal spectrometers. There are few studies on the calibration transfer of soil nutrient concentration from a hyperspectral camera to a normal spectrometer. In this paper, 164 soil samples from three regions in Qingdao, China, were collected. The spectral data of normal spectrometer and hyperspectral camera and the concentration of total carbon and nitrogen were obtained. And then, the models of soil total carbon and nitrogen content were established by using the spectral data of a normal spectrometer. The hyperspectral data were transferred by a variety of methods, such as single conventional calibration transfer algorithm, combination of multiple calibration transfer algorithms, and calibration transfer algorithm after spectral pretreatment. The transferred hyperspectral data were predicted by the total carbon and total nitrogen concentration model established by using a normal spectrometer. The absolute coefficients Rt2 and root mean square error of prediction (RMSEP) were used to evaluate the prediction performance after calibration transfer. After trying many calibration transfer methods, the prediction performance of calibration transfer by the Repfile-PDS and Repfile-SNV methods was the best. In the calibration transfer of the Repfile-PDS method, when the number of PDS windows was 27 and the number of standard data was 40, the Rt2 and the RMSEP of TC concentration were 0.627 and 2.351. When the number of PDS windows was 25 and the number of standard data was 100, the Rt2 and the RMSEP of TN concentration were 0.666 and 0.297. In the calibration transfer of the Repfile-SNV method, when the number of TC and TN standard data was 120, the Rt2 was the largest, 0.701 and 0.722, respectively, and the RMSEP was 2.880 and 0.399, respectively. After the hyperspectral data were calibration transferred by the above algorithms, they could be predicted by the soil TC and TN concentration model established by using a normal spectrometer, and better prediction results can be obtained. The solution of the calibration transfer of soil nutrient concentration from the hyperspectral camera to the normal spectrometer provides a powerful basis for rapid prediction of a large number of image information data collected by using a hyperspectral camera. It greatly reduces the workload and promotes the application of hyperspectral camera in quantitative analysis and rapid measurement technology.

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Tan, Huwei, Stephen T. Sum, and Steven D. Brown. "Improvement of a Standard-Free Method for Near-Infrared Calibration Transfer." Applied Spectroscopy 56, no. 8 (August 2002): 1098–106. http://dx.doi.org/10.1366/000370202321275015.

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Previously, a standard-free method using the finite impulse response (FIR) filter was successfully employed to transfer the NIR spectra of caustic brines, analgesics, and terpolymer resins. This paper carries the FIR transfer method one step further, leading to an improved algorithm that makes the transfer more robust and general by avoiding transfer artifacts in the filtered spectra. Investigations of the theoretical aspects and application examples of diffuse reflectance NIR datasets show that in comparison with our previous version the improved method is much easier to use and gives artifact-free transferred spectra. The improved method also compares favorably with other current signal correction methods for calibration transfer. With the additional advantage of not requiring a subset of standards to be measured on main and remote instruments, the proposed method is a very useful alternative for calibration transfer.

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Poerio, Dominic V., and Steven D. Brown. "Dual-Domain Calibration Transfer Using Orthogonal Projection." Applied Spectroscopy 72, no. 3 (August 8, 2017): 378–91. http://dx.doi.org/10.1177/0003702817724164.

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We report the use of dual-domain regression models, which were built utilizing a wavelet prism decomposition and paired with transfer by orthogonal projection, for the calibration transfer of near-infrared (NIR) spectra. The new method is based on obtaining specific frequency components for a spectrum via wavelet analysis, projecting the frequency components of the primary instrument onto the subspace orthogonal to the mean instrumental difference between spectra from the primary and the secondary instrument, and weighting each frequency component model according to the cross-validation error of the frequency components of the projected primary instrument’s spectra to generate a stacked ensemble model robust to contributions to the spectra from instrumental variations. The method, which does not require property values from the secondary data set, is tested on three NIR data sets, and is compared with orthogonal projection in the wavelength domain, orthogonal signal correction, and with model updating approaches. For the data sets we examined, we show that the prediction performance of the new method is competitive with orthogonal projections in the wavelength domain, as well as orthogonal signal correction and model updating approaches, both of which require property values for spectra from the secondary instrument. Examination of the spectral data reconstructed from the projected frequency components indicates that aspects of the data that may be attributable to instrumental or physical phenomena (i.e., instrumental baseline shifts or discretized intensity changes which may be attributed to scatter) are suppressed, but those associated with the chemical phenomena are retained. The benefits of orthogonal projection on each individual frequency component are further corroborated by the fact that the models based on frequency component projection generalize better to unseen instruments compared with the other methods.

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Kobusch, M., and L. Klaus. "In-situ dynamic force calibration using impact hammers." ACTA IMEKO 9, no. 5 (December 31, 2020): 118. http://dx.doi.org/10.21014/acta_imeko.v9i5.952.

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This paper presents experimental investigations of in-situ dynamic force calibrations in which an impact hammer provides the dynamic reference force. Here, the force transducer to be calibrated remains in the original mechanical structure of the force measurement application to which calibration shock forces are applied in a suitable way. Numerous experiments with different force transducer set-ups and different impact hammer configurations were conducted to validate this in- situ calibration method. The paper describes the analysis of the measurement data and presents the force transfer functions obtained. Finally, these dynamic calibration results are discussed.

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Wang, Ling, Xiuqing Hu, Lin Chen, and Lingli He. "Consistent Calibration of VIRR Reflective Solar Channels Onboard FY-3A, FY-3B, and FY-3C Using a Multisite Calibration Method." Remote Sensing 10, no. 9 (August 22, 2018): 1336. http://dx.doi.org/10.3390/rs10091336.

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The FengYun-3 (FY-3) Visible Infrared Radiometer (VIRR), along with its predecessor, the Multispectral Visible Infrared Scanning Radiometer (MVISR), onboard the FY-1C and FY-1D, has collected continuous daily global observations for 18 years. Achieving accurate and consistent calibration for VIRR reflective solar bands (RSBs) has been challenging, as there is no onboard calibrator and the frequency of in situ vicarious calibration is limited. In this study, a new set of reflectance calibration coefficients were derived for RSBs of the FY-3A, FY-3B, and FY-3C VIRRs using a multisite (MST) calibration method. This method is an extension of a previous MST calibration method, which relies on radiative transfer modeling over the multiple stable earth sites, and no synchronous in situ measurements are needed; hence, it can be used to update the VIRR calibration on a daily basis. The on-orbit radiometric changes of the VIRR onboard the FY-3 series were assessed based on analyses of new sets of calibration slopes. Then, all recalibrated VIRR reflectance data over Libya 4, the most frequently used stable Earth site, were compared with those provided from the Level 1B (L1B) product. Additional validation was performed by comparing the recalibrated VIRR data with those derived from radiative transfer simulations using measurements from automatic calibration instruments in Dunhuang. The results indicate that the radiometric response changes of the VIRRs onboard FY-3A and FY-3B were larger than those of FY-3C VIRR and were wavelength dependent. The current approach can provide consistent VIRR reflectances across different FY-3 satellite platforms. After recalibration, differences in top-of-atmosphere (TOA) reflectance data across different VIRRs during the whole lifetime decreased from 5–10% to less than 3%. The comparison with the automatic calibration method indicates that MST calibration shows good accuracy and lower temporal oscillations.

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Wagner, T., S. Beirle, S. Dörner, M. Penning de Vries, J. Remmers, A. Rozanov, and R. Shaiganfar. "A new method for the absolute radiance calibration for UV–vis measurements of scattered sunlight." Atmospheric Measurement Techniques 8, no. 10 (October 14, 2015): 4265–80. http://dx.doi.org/10.5194/amt-8-4265-2015.

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Abstract. Absolute radiometric calibrations are important for measurements of the atmospheric spectral radiance. Such measurements can be used to determine actinic fluxes, the properties of aerosols and clouds, and the shortwave energy budget. Conventional calibration methods in the laboratory are based on calibrated light sources and reflectors and are expensive, time consuming and subject to relatively large uncertainties. Also, the calibrated instruments might change during transport from the laboratory to the measurement sites. Here we present a new calibration method for UV–vis instruments that measure the spectrally resolved sky radiance, for example zenith sky differential optical absorption spectroscopy (DOAS) instruments or multi-axis (MAX)-DOAS instruments. Our method is based on the comparison of the solar zenith angle dependence of the measured zenith sky radiance with radiative transfer simulations. For the application of our method, clear-sky measurements during periods with almost constant aerosol optical depth are needed. The radiative transfer simulations have to take polarisation into account. We show that the calibration results are almost independent from the knowledge of the aerosol optical properties and surface albedo, which causes a rather small uncertainty of about < 7 %. For wavelengths below about 330 nm it is essential that the ozone column density during the measurements be constant and known.

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Zhao, Yuhui, Ziheng Zhao, Peng Shan, Silong Peng, Jinlong Yu, and Shuli Gao. "Calibration Transfer Based on Affine Invariance for NIR without Transfer Standards." Molecules 24, no. 9 (May 9, 2019): 1802. http://dx.doi.org/10.3390/molecules24091802.

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Calibration transfer is an important field for near-infrared (NIR) spectroscopy in practical applications. However, most transfer methods are constructed with standard samples, which are expensive and difficult to obtain. Taking this problem into account, this paper proposes a calibration transfer method based on affine invariance without transfer standards (CTAI). Our method can be utilized to adjust the difference between two instruments by affine transformation. CTAI firstly establishes a partial least squares (PLS) model of the master instrument to obtain score matrices and predicted values of the two instruments, and then the regression coefficients between each of the score vectors and predicted values are computed for the master instrument and the slave instrument, respectively. Next, angles and biases are calculated between the regression coefficients of the master instrument and the corresponding regression coefficients of the slave instrument, respectively. Finally, by introducing affine transformation, new samples are predicted based on the obtained angles and biases. A comparative study between CTAI and the other five methods was conducted, and the performances of these algorithms were tested with two NIR spectral datasets. The obtained experimental results show clearly that, in general CTAI is more robust and can also achieve the best Root Mean Square Error of test sets (RMSEPs). In addition, the results of statistical difference with the Wilcoxon signed rank test show that CTAI is generally better than the others, and at least statistically the same.

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Wagner, T., S. Beirle, S. Dörner, M. Penning de Vries, J. Remmers, A. Rozanov, and R. Shaiganfar. "A new method for the absolute radiance calibration for UV/vis measurements of scattered sun light." Atmospheric Measurement Techniques Discussions 8, no. 5 (May 28, 2015): 5329–62. http://dx.doi.org/10.5194/amtd-8-5329-2015.

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Abstract. Absolute radiometric calibrations are important for measurements of the atmospheric spectral radiance. Such measurements can be used to determine actinic fluxes, the properties of aerosols and clouds and the short wave energy budget. Conventional calibration methods in the laboratory are based on calibrated light sources and reflectors and are expensive, time consuming and subject to relatively large uncertainties. Also, the calibrated instruments might change during transport from the laboratory to the measurement sites. Here we present a new calibration method for UV/vis instruments that measure the spectrally resolved sky radiance, like for example zenith sky Differential Optical Absorption Spectroscopy (DOAS-) instruments or Multi-AXis (MAX-) DOAS instruments. Our method is based on the comparison of the solar zenith angle dependence of the measured zenith sky radiance with radiative transfer simulations. For the application of our method clear sky measurements during periods with almost constant aerosol optical depth are needed. The radiative transfer simulations have to take polarisation into account. We show that the calibration results are almost independent from the knowledge of the aerosol optical properties and surface albedo, which causes a rather small uncertainty of about <7%. For wavelengths below about 330 nm it is essential that the ozone column density during the measurements is constant and known.

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Hovell, Tom, Jon Petzing, Laura Justham, and Peter Kinnell. "Pragmatic Micrometre to Millimetre Calibration Using Multiple Methods for Low-Coherence Interferometer in Embedded Metrology Applications." Sensors 21, no. 15 (July 28, 2021): 5101. http://dx.doi.org/10.3390/s21155101.

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In-situ metrology utilised for surface topography, texture and form analysis along with quality control processes requires a high-level of reliability. Hence, a traceable method for calibrating the measurement system’s transfer function is required at regular intervals. This paper compares three methods of dimensional calibration for a spectral domain low coherence interferometer using a reference laser interferometer versus two types of single material measure. Additionally, the impact of dataset sparsity is shown along with the effect of using a singular calibration dataset for system performance when operating across different media.

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Li, Zhengqiang, Kaitao Li, Donghui Li, Jiuchun Yang, Hua Xu, Philippe Goloub, and Stephane Victori. "Simple transfer calibration method for a Cimel Sun–Moon photometer: calculating lunar calibration coefficients from Sun calibration constants." Applied Optics 55, no. 27 (September 20, 2016): 7624. http://dx.doi.org/10.1364/ao.55.007624.

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Seeger, Benedikt, and Thomas Bruns. "Primary calibration of mechanical sensors with digital output for dynamic applications." ACTA IMEKO 10, no. 3 (September 30, 2021): 177. http://dx.doi.org/10.21014/acta_imeko.v10i3.1075.

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This article tackles the challenge of the dynamic calibration of modern sensors with integrated data sampling and purely digital output for the measurement of mechanical quantities like acceleration, angular velocity, force, pressure, or torque. Based on the established calibration methods using sine excitation, it describes an extension of the established methods and devices that yields primary calibration results for the magnitude and phase of the complex transfer function. The system is demonstrated with a focus on primary accelerometer calibrations but can easily be transferred to the other mechanical quantities. Furthermore, it is shown that the method can be used to investigate the quality and characteristics of the timing for the internal sampling of such digital output sensors. Thus, it is able to gain crucial information for any subsequent phase-related measurements with such sensors.

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Shan, Peng, Yuhui Zhao, Qiaoyun Wang, Shuyu Wang, Yao Ying, and Silong Peng. "A nonlinear calibration transfer method based on joint kernel subspace." Chemometrics and Intelligent Laboratory Systems 210 (March 2021): 104247. http://dx.doi.org/10.1016/j.chemolab.2021.104247.

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Xu, Zhuopin, Shuang Fan, Jing Liu, Binmei Liu, Liangzhi Tao, Jin Wu, Shupeng Hu, Liping Zhao, Qi Wang, and Yuejin Wu. "A calibration transfer optimized single kernel near-infrared spectroscopic method." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 220 (September 2019): 117098. http://dx.doi.org/10.1016/j.saa.2019.05.003.

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Xu, Zhuopin, Shuang Fan, Weimin Cheng, Jie Liu, Pengfei Zhang, Yang Yang, Cong Xu, et al. "A correlation-analysis-based wavelength selection method for calibration transfer." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 230 (April 2020): 118053. http://dx.doi.org/10.1016/j.saa.2020.118053.

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Hou, Zhi Wei, Min Zhao, Ai Min Dong, Qiong Wu, and Qiu Feng Li. "Compact Method to Calibrate Frequency Response of Ultrasonic Transducer." Advanced Materials Research 171-172 (December 2010): 416–20. http://dx.doi.org/10.4028/www.scientific.net/amr.171-172.416.

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Frequency response character of ultrasonic transducer often influences on the test signal partly, and then test errors arise. To the problem, a compact method is proposed to calibrate the frequency response in this paper. The experiment data was obtained in water- immerging test of the transducers, and a discrete transfer function is established based on system identification algorithms and then used for transducer calibration. The method is validated effective by experiment. Not only can the characteristic of transducers be indicated, but also a referenced method is presented for calibrating frequency response of LTI system.

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An, Pengju, Chaoqun Wei, Huiming Tang, Qinglu Deng, Bofan Yu, and Kun Fang. "An Improved Calibration Method to Determine the Strain Coefficient for Optical Fibre Sensing Cables." Photonics 8, no. 10 (October 7, 2021): 429. http://dx.doi.org/10.3390/photonics8100429.

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The strain coefficient of an optical fibre sensing cable is a critical parameter for a distributed optical fibre sensing system. The conventional tensile load test method tends to underestimate the strain coefficient of sensing cables due to slippage or strain transfer loss at the fixing points during the calibration procedure. By optimizing the conventional tensile load test setup, the true strain of a sensing cable can be determined by using two sets of displacement measuring equipment. Thus, the strain calculation error induced by slippage or strain transfer loss between a micrometre linear stage and sensing cable can be avoided. The performance of the improved calibration method was verified by using three types of sensing cables with different structures. In comparison to the conventional tensile load test method, the strain coefficients obtained by the improved calibration method for sensing cables A, B, and C increase by 1.52%, 2.06%, and 1.86%, respectively. Additionally, the calibration errors for the improved calibration method are discussed. The test results indicate that the improved calibration method has good practicability and enables inexperienced experimenters or facilities with limited equipment to perform precise strain coefficient calibration for optical fibre sensing cables.

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Chen, Wo-Ruo, Jun Bin, Hong-Mei Lu, Zhi-Min Zhang, and Yi-Zeng Liang. "Calibration transfer via an extreme learning machine auto-encoder." Analyst 141, no. 6 (2016): 1973–80. http://dx.doi.org/10.1039/c5an02243f.

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A novel spectra standardization algorithm titled Transfer via Extreme learning machine Auto-encoder Method (TEAM) has been proposed. Compared with commonly used methods like PDS, GLS and CCA, TEAM is more stable and can significantly reduce prediction errors.

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Fearn, Tom, Colin Eddison, Robin Withey, and Ian A. Cowe. "A Method for Wavelength Standardisation in Filter Instruments." Journal of Near Infrared Spectroscopy 4, no. 1 (January 1996): 111–18. http://dx.doi.org/10.1255/jnirs.82.

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One of the factors affecting the successful transfer of calibrations between different near infrared filter instruments from the same production line is the existence of small differences in the wavelength response of nominally identical filters. A method is described for standardising spectral data from a production instrument to correct for wavelength differences between its filters and those of a master instrument. A chemometric approach combines spectral scans of both sets of filters with information about the spectra of the samples to be measured in order to derive appropriate corrections. The result is a matrix of correction factors that can be programmed into the instrument to improve calibration transferability.

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Zhang, Hui, Haining Tan, Boran Lin, Xiangchun Yang, Zhongyu Sun, Liang Zhong, Lele Gao, et al. "Improved Principal Component Analysis (IPCA): A Novel Method for Quantitative Calibration Transfer between Different Near-Infrared Spectrometers." Molecules 28, no. 1 (January 3, 2023): 406. http://dx.doi.org/10.3390/molecules28010406.

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Given the labor-consuming nature of model establishment, model transfer has become a considerable topic in the study of near-infrared (NIR) spectroscopy. Recently, many new algorithms have been proposed for the model transfer of spectra collected by the same types of instruments under different situations. However, in a practical scenario, we need to deal with model transfer between different types of instruments. To expand model applicability, we must develop a method that could transfer spectra acquired from different types of NIR spectrometers with different wavenumbers or absorbance. Therefore, in our study, we propose a new methodology based on improved principal component analysis (IPCA) for calibration transfer between different types of spectrometers. We adopted three datasets for method evaluation, including public pharmaceutical tablets (dataset 1), corn data (dataset 2), and the spectra of eight batches of samples acquired from the plasma ethanol precipitation process collected by FT-NIR and MicroNIR spectrometers (dataset 3). In the calibration transfer for public datasets, IPCA displayed comparable results with the classical calibration transfer method using piecewise direct standardization (PDS), indicating its obvious ability to transfer spectra collected from the same types of instruments. However, in the calibration transfer for dataset 3, our proposed IPCA method achieved a successful bi-transfer between the spectra acquired from the benchtop and micro-instruments with/without wavelength region selection. Furthermore, our proposed method enabled improvements in prediction ability rather than the degradation of the models built with original micro spectra. Therefore, our proposed method has no limitations on the spectrum for model transfer between different types of NIR instruments, thus allowing a wide application range, which could provide a supporting technology for the practical application of NIR spectroscopy.

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Li, Lisha, Bin Li, Xiaogang Jiang, and Yande Liu. "A Standard-Free Calibration Transfer Strategy for a Discrimination Model of Apple Origins Based on Near-Infrared Spectroscopy." Agriculture 12, no. 3 (March 4, 2022): 366. http://dx.doi.org/10.3390/agriculture12030366.

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The nondestructive discrimination model based on near-infrared is usually established by detected spectra and chemometric methods. However, the inherent differences between instruments prevent the model from being used universally, and calibration transfer is often used to solve these problems. Standard-sample calibration transfer requires additional standard samples to build a mathematical mapping between instruments. Thus, standard-free calibration transfer is a research hotspot in this field. Based on near-infrared spectroscopy (NIRS), the new combined strategy of wavelength selection and standard-free calibration transfer was proposed to transfer the model between two portable near-infrared spectrometers. Three transfer learning (TL) algorithms—transferred component analysis (TCA), balanced distribution adaptation (BDA), and manifold embedded distribution alignment (MEDA)—were applied to achieve standard-free calibration transfer. Moreover, this paper presents a relative error analysis (REA) method to select wavelength. To select the optimal model, the parameters of accuracy, precision, and recall were examined to evaluate the discriminatory capacities of each model. The findings show that the MEDA-REA model is capable of higher prediction accuracy (accuracy = 94.54%) than the other transferring models (TCA, BDA, MEDA, TCA-REA, and BDA-REA), and it is demonstrated that the new strategy has good transmission performance. Moreover, REA shows the potential to filter wavebands for calibration transfer and simplify the transferable model.

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Kit, E., A. Cherkassky, T. Sant, and H. J. S. Fernando. "In Situ Calibration of Hot-Film Probes Using a Collocated Sonic Anemometer: Implementation of a Neural Network." Journal of Atmospheric and Oceanic Technology 27, no. 1 (January 1, 2010): 23–41. http://dx.doi.org/10.1175/2009jtecha1320.1.

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Abstract Although the integral quantities of atmospheric turbulence are conveniently measured using sonic anemometers, obtaining relevant finescale variables such as the kinetic energy dissipation using conventional hot-film/wire techniques remains a challenge because of two main difficulties. The first difficulty is the mean wind variability, which causes violation of the requirement that mean winds have a specific alignment with the hot-film/wire probe. To circumvent this problem, a combination of collocated sonic and hot-film anemometers, with the former measuring mean winds and aligning the latter in the appropriate wind direction via an automated platform, is successfully designed and implemented. The second difficulty is the necessity of frequent and onerous calibrations akin to hot-film anemometry that lead to logistical difficulties during outdoor (field) measurements. This is addressed by employing sonic measurements to calibrate the hot films in the same combination, with the output (velocity) to input (voltage) transfer function for the hot film derived using a neural network (NN) model. The NN is trained using low-pass-filtered hot-film and sonic data taken in situ. This new hot-film calibration procedure is compared with the standard calibration method based on an external calibrator. It is inferred that the sonic-based NN method offers great potential as an alternative to laborious standard calibration techniques, particularly in the laboratory and in stable atmospheric boundary layer settings. The NN approximation technique is found to be superior to the conventionally used polynomial fitting methods when used in conjunction with unevenly spaced calibration velocity data generated by sonic anemometers.

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KUMAR, HARISH. "A CONTEMPORARY APPROACH FOR EVALUATION OF THE BEST MEASUREMENT CAPABILITY OF A FORCE CALIBRATION MACHINE." International Journal of Modern Physics: Conference Series 24 (January 2013): 1360013. http://dx.doi.org/10.1142/s2010194513600136.

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The present paper discusses the procedure for evaluation of best measurement capability of a force calibration machine. The best measurement capability of force calibration machine is evaluated by a comparison through the precision force transfer standards to the force standard machines. The force transfer standards are calibrated by the force standard machine and then by the force calibration machine by adopting the similar procedure. The results are reported and discussed in the paper and suitable discussion has been made for force calibration machine of 200 kN capacity. Different force transfer standards of nominal capacity 20 kN, 50 kN and 200 kN are used. It is found that there are significant variations in the .uncertainty of force realization by the force calibration machine according to the proposed method in comparison to the earlier method adopted.

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Zhang, Jin, Xiaoyu Cui, Wensheng Cai, and Xueguang Shao. "Modified linear model correction: A calibration transfer method without standard samples." NIR news 29, no. 8 (September 26, 2018): 24–27. http://dx.doi.org/10.1177/0960336018804395.

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Calibration transfer without standard samples is essential for practical applications of near infrared spectroscopy because, sometimes, it is difficult or even impossible to obtain the standard samples for measuring their spectra on the secondary instrument. In this work, a modified linear model correction method is proposed for improving the transfer accuracy and computational efficiency. The constraint of linear model correction was replaced by a robust convex equation to restrict the model similarity in the optimization. The near infrared dataset of pharmaceutical tablet measured with different instruments are used to test the performance of the method. The result shows that a modified linear model correction achieves a high efficiency of the transfer while the computational complexity can be considerably reduced. The method may provide a robust way in practical application.

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Jiang Feng, 江丰, 钮新华 Niu Xinhua, and 殷恺 Yin Kai. "反射率传递光谱仪衰减孔阑的定标方法研究." Laser & Optoelectronics Progress 59, no. 1 (2022): 0112002. http://dx.doi.org/10.3788/lop202259.0112002.

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Hsieh, Tsung-Han, Tsukasa Watanabe, and Po-Er Hsu. "Calibration of Rotary Encoders Using a Shift-Angle Method." Applied Sciences 12, no. 10 (May 16, 2022): 5008. http://dx.doi.org/10.3390/app12105008.

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Cross-calibration using an autocollimator and a polygon is the traditional method for calibrating a rotary encoder. These angles, which can be calibrated using this method, are limited by the pitch angle of the polygon, which is 15° for a 24-faced polygon. In this work, we propose a new shift-angle method using the same setup as the traditional method. However, the new method can measure smaller than the pitch angle of the polygon, which is the measurement limitation of the traditional method. The proposed method can calibrate every angle of the rotary encoder. In the experiment, we use an autocollimator and a 24-faced polygon to calibrate the SelfA rotary encoder to verify the proposed shift-angle method. The SelfA rotary encoder, which comprises one rotary encoder and 12 read heads, is calibrated using self-calibration. The difference between the calibration results obtained by applying these two methods to the same SelfA rotary encoder is smaller than ±0.1″.

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Thi Ngoc Trang, Le, Huynh Dinh Chuong, and Tran Thien Thanh. "Efficiency calibration for HPGe detector by Monte Carlo efficiency transfer method." Science and Technology Development Journal - Natural Sciences 3, no. 1 (March 29, 2019): 9–17. http://dx.doi.org/10.32508/stdjns.v3i1.712.

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In this paper, the Monte Carlo efficiency transfer method was used to calibrate the full energy peak efficiency (FEPE) of a coaxial p-type HPGe detector. The gamma standard radioactive sources including 22Na, 54Mn, 57Co, 60Co, 65Zn, 109Cd,133Ba, 137Cs, 154Eu, 207Bi, 241Am were measured at different positions on-center of detector with the distance of 5, 10, 15, 20, 25 cm. Besides, a cylindrical sample containing standard mixed nuclides solution was also measured at surface of the detector. The experimental FEPE curves as function of gamma energy for these geometries were determined with the coincidence-summing corrections. A HPGe detector model based on the specifications of manufacturer was built to directly calculate the FEPE for the geometries by Monte Carlo simulations with MCNP6 code. However, these simulated FEPEs show a quite high discrepancy from experimental FEPEs. Then, the FEPEs were calculated by the efficiency transfer method with the efficiency curve for point source at distance of 25 cm as the reference data. A good agreement was obtained between the calculated results by the Monte Carlo efficiency transfer method and experimental results. The comparisons between experimental and calculated FEPE showed that the relative deviations were mostly within +/-4% in the energy range of 53-1770 keV.

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Zhao, Yuhui, Jinlong Yu, Peng Shan, Ziheng Zhao, Xueying Jiang, and Shuli Gao. "PLS Subspace-Based Calibration Transfer for Near-Infrared Spectroscopy Quantitative Analysis." Molecules 24, no. 7 (April 2, 2019): 1289. http://dx.doi.org/10.3390/molecules24071289.

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In order to enable the calibration model to be effectively transferred among multiple instruments and correct the differences between the spectra measured by different instruments, a new feature transfer model based on partial least squares regression (PLS) subspace (PLSCT) is proposed in this paper. Firstly, the PLS model of the master instrument is built, meanwhile a PLS subspace is constructed by the feature vectors. Then the master spectra and the slave spectra are projected into the PLS subspace, and the features of the spectra are also extracted at the same time. In the subspace, the pseudo predicted feature of the slave spectra is transferred by the ordinary least squares method so that it matches the predicted feature of the master spectra. Finally, a feature transfer relationship model is constructed through the feature transfer of the PLS subspace. This PLS-based subspace transfer provides an efficient method for performing calibration transfer with only a small number of standard samples. The performance of the PLSCT was compared and assessed with slope and bias correction (SBC), piecewise direct standardization (PDS), calibration transfer method based on canonical correlation analysis (CCACT), generalized least squares (GLSW), multiplicative signal correction (MSC) methods in three real datasets, statistically tested by the Wilcoxon signed rank test. The obtained experimental results indicate that PLSCT method based on the PLS subspace is more stable and can acquire more accurate prediction results.

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Jiao, Hong Wei, Shi Qiao Qin, Chun Sheng Hu, and Xing Shu Wang. "A New Extrinsic Calibration Method of Three-Dimensional Imaging Lidar and Camera." Applied Mechanics and Materials 58-60 (June 2011): 2194–99. http://dx.doi.org/10.4028/www.scientific.net/amm.58-60.2194.

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Three-dimensional imaging lidar can offer the range information and CCD camera can offer the color information of the target. These two information can strongly supplement each other, the fusion of them is becoming a research hot point. The major problem of fusing lidar data and camera data is the coordinate calibration between them. In consideration of the traits of lidar and camera, a new planar object calibration method was proposed, which solves extrinsic matrix using the normal of planar objects. The rotation matrix and transfer vector are solved separately, which can simplify the calibration process and highly improve the calibration precision. The improved extrinsic calibration method was applied on texture mapping and reverse mapping, which show that our algorithm can gives good results.

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Boineau, F., M. D. Plimmer, and E. Mahé. "Volume calibration using a comparison method with a transfer leak flow rate." ACTA IMEKO 9, no. 5 (December 31, 2020): 343. http://dx.doi.org/10.21014/acta_imeko.v9i5.997.

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This paper describes a volume comparison method carried out under a fine/rough vacuum using a small transfer flow rate from a capillary leak artefact. This method is suitable for volumes of vessels with complex shapes such as tubing arrangements equipped with various pneumatic parts (valves, gauges …), sample volumes, etc. The calibration, based on pressure rise measurements performed with a constant-volume flowmeter set-up, exhibits a standard relative uncertainty between 0.03 % and 2 % for volumes ranging from 1 to 3000 cm³, which is only about one order of magnitude higher than capabilities of the gravimetric volume calibration.

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Qiu, Jinhuan, Xiangao Xia, Jianghui Bai, Pucai Wang, Xuemei Zong, and Daren Lu. "A New Method to Calibrate Shortwave Solar Radiation Measurements." Journal of Atmospheric and Oceanic Technology 31, no. 6 (June 1, 2014): 1321–29. http://dx.doi.org/10.1175/jtech-d-13-00114.1.

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Abstract A method is proposed to simultaneously calibrate shortwave (0.3–4 μm) global, direct, and scattering solar irradiance (GSI, DSI, and SSI, respectively) measurements. The method uses the World Radiation Reference (WRR) as a calibration standard and on-site radiation measurements as inputs. Two simple but effective techniques are used in the calibration. The first is to scale SSI and GSI detection sensitivities under overcast skies, which is based on the assumption that SSI should be equal to GSI if DSI is completely scattered and absorbed. The second is a new method to retrieve aerosol optical thickness (AOT), using the ratio of horizontal DSI (HDSI) to GSI measurements under clear and clean conditions. Thereafter, retrieved AOTs are used to drive a radiative transfer model to calculate atmospheric transmittance and then a ratio of GSI to the transmittance. Deviation of this ratio to the WRR is regarded as an indicator of GSI uncertainty, and the calibration transfer coefficient is derived as the WRR ratio. The method is applied to calibrate radiation measurements at Xianghe, China, during 2005. It is estimated from the derived transfer coefficients on 36 clear and clean days that uncertainties of DSI, GSI, and SSI measurements are within −4.0% to 2.9%, −5.9% to 2.4%, and −6.1% to 4.9%, respectively. The calibration is further validated based on comparisons of AOT at 750 nm retrieved from HDSI/GSI to Aerosol Robotic Network (AERONET) AOT products. The maximum deviation between two AOT products is 0.026. The unique advantage of this method lies in its potential applications in correcting historic radiation measurements and monitoring radiometer performance.

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Zhang, Min, Chenyang Wang, Wenli Zhu, and Yi Shen. "An Intelligent DOA Estimation Error Calibration Method Based on Transfer Learning." Applied Sciences 12, no. 15 (July 28, 2022): 7636. http://dx.doi.org/10.3390/app12157636.

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Affected by various error factors in the actual environment, the accuracy of the direction of arrival (DOA) estimation algorithm will greatly decrease during an application. To address this issue, in this paper, we propose an intelligent DOA estimation error calibration method based on transfer learning, which learns error knowledge from a small number of actual signal samples and improves the DOA estimation accuracy in the real application. We constructed a deep convolutional neural network (CNN)-based intelligent DOA estimation model to learn the mapping between the input signals and their azimuths. We generated a large number of ideal simulation signal samples to train the CNN model and used it as the pretrained model. Then, we fine-tuned the CNN model with a small number of actual signal samples collected in the actual environment. We demonstrate the effectiveness of the proposed method through simulation experiments. The experimental results indicate that the proposed method can effectively improve the accuracy of DOA estimation in the actual environment.

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Lu, Jiazhen, Lili Ye, and Jong Dong. "Applied singular value decomposition method in transfer alignment and bias calibration." IET Radar, Sonar & Navigation 14, no. 5 (May 2020): 700–706. http://dx.doi.org/10.1049/iet-rsn.2019.0397.

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Xu, Jiangtao, Xiaolin Shi, Jiawen Li, Kaiming Nie, and Jianguo Ma. "The Calibration Method for Incomplete Charge Transfer in ToF Image Sensor." IEEE Sensors Journal 20, no. 17 (September 1, 2020): 9928–36. http://dx.doi.org/10.1109/jsen.2020.2991203.

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Rodriguez, S., V. Gibiat, A. Lefebvre, and Stephane Guilain. "The three-measurement two-calibration method for measuring the transfer matrix." Journal of the Acoustical Society of America 129, no. 5 (May 2011): 3056–67. http://dx.doi.org/10.1121/1.3557058.

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Wang, Ke, Yantao Duan, Lihua Shi, and Shi Qiu. "Laboratory Calibration of D-dot Sensor Based on System Identification Method." Sensors 19, no. 15 (July 24, 2019): 3255. http://dx.doi.org/10.3390/s19153255.

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D-dot sensors can realize the non-contact measurement of transient electric fields, which is widely applied to electromagnetic pulse (EMP) measurements with characteristics of the wide frequency band, high linearity, and good stability. In order to achieve accurate calibration of D-dot sensors in the laboratory environment, this paper proposed a new calibration method based on system identification. Firstly, the D-dot sensor can be considered as a linear time-invariant (LTI) system under corner frequency, thus its frequency response can be characterized by the transfer function of a discrete output error (OE) model. Secondly, based on the partial linear regression of the transfer function curve, the sensitivity coefficient of the D-dot sensor is obtained. By increasing the influence weight of low-frequency components, this proposed method has better calibration performance when the waveform is distorted in the time domain, and can artificially adapt to the operating frequency range of the sensor at the same time.

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Balenzategui, José Lorenzo, María Molero, José Pedro Silva, Fernando Fabero, José Cuenca, Eduardo Mejuto, and Javier De Lucas. "Uncertainty in the Calibration Transfer of Solar Irradiance Scale: From Absolute Cavity Radiometers to Standard Pyrheliometers." Solar 2, no. 2 (April 2, 2022): 158–85. http://dx.doi.org/10.3390/solar2020010.

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In this work, the method for calculation of uncertainty of pyrheliometers’ responsivity during their outdoor calibration process in the laboratory is exposed. It is applied first for calibration of standard pyrheliometers by comparison to cavity radiometers, and after for calibration of an end-user pyrheliometer against that standard pyrheliometer. The dissemination of the WRR irradiance scale is illustrated in practice and the increasing uncertainty in the traceability chain is quantified. The way of getting traceability to both WRR scale and to SI units in the current situation, where the shift between these radiometric scales is pending to be solved, is also explained. However, the impact of this gap between scales seems to be more important for calibrations of reference Class A pyrheliometers than in the final determination of DNI irradiance, because in this case, the cumulative uncertainty is large enough as to not significantly be affected for the difference. The way to take into account different correction terms in the measurement model function, and how to compute the corresponding uncertainty, is explained too. The influence of temperature of some pyrheliometers during calibration process and the potential impact on the DNI irradiance calculated with these instruments is exemplified.

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Müller, T., A. Virkkula, and J. A. Ogren. "Constrained two-stream algorithm for calculating aerosol light absorption coefficient from the Particle Soot Absorption Photometer." Atmospheric Measurement Techniques 7, no. 12 (December 2, 2014): 4049–70. http://dx.doi.org/10.5194/amt-7-4049-2014.

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Abstract. We present a new correction scheme for filter-based absorption photometers based on a constrained two-stream (CTS) radiative transfer model and experimental calibrations. The two-stream model was initialized using experimentally accessible optical parameters of the filter. Experimental calibrations were taken from the literature and from dedicated experiments for the present manuscript. Uncertainties in the model and calibration experiments are discussed and uncertainties for retrieval of absorption coefficients are derived. For single-scattering albedos lower than 0.8, the new CTS method and also other correction schemes suffer from the uncertainty in calibration experiments, with an uncertainty of about 20% in the absorption coefficient. For high single-scattering albedos, the CTS correction significantly reduces errors. At a single-scattering albedo of about 0.98 the error can be reduced to 30%, whereas errors using the Bond correction (Bond et al., 1999) are up to 100%. The correction scheme was tested using data from an independent experiment. The tests confirm the modeled performance of the correction scheme when comparing the CTS method to other established correction methods.

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Niedzwiedz, Angelika, Jens Duffert, Mario Tobar-Foster, Jan Wilko Heinzel, and Gunther Seckmeyer. "Field calibration for multidirectional spectroradiometers." Measurement Science and Technology 33, no. 6 (March 11, 2022): 065904. http://dx.doi.org/10.1088/1361-6501/ac56be.

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Abstract A mobile calibration system for a multidirectional spectroradiometer (MUDIS) to transfer the absolute radiometric calibration from the laboratory to the location of the outdoor-measurement (field calibrator) has been developed. The main part of the calibration system comprises an aluminium sphere with a diameter of 40 cm, mounting adapters and a ventilation system. The MUDIS device is capable of measuring spectral radiance from 320 to 600 nm in 113 different directions simultaneously within 1 s. When repeating radiance measurements inside the mobile field sphere, the relative standard deviation (RSD) for wavelengths between 320 and 600 nm is less than 1.8% (320 nm) for all directions with minimum RSD of 0.6% at 382 nm. The reproducibility depends not only on the wavelength but also on the individual fibre position on the hemispherical input optics, with maximum of 4.5% RSD, but most directions show a lower deviation. On average, the RSD for the channels is less than 0.9%. The calibrator enables measurements of the spectral radiance with less uncertainty than with the previous indirect calibration method, which uses measurements of a scanning reference array spectroradiometer.

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Tang, Hongzhao, Junfeng Xie, Wei Chen, Honggeng Zhang, and Hengyang Wang. "Absolute Radiometric Calibration of ZY3-02 Satellite Multispectral Imager Based on Irradiance-Based Method." Remote Sensing 15, no. 2 (January 11, 2023): 448. http://dx.doi.org/10.3390/rs15020448.

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In this paper, an irradiance-based absolute radiometric calibration campaign at Baotou calibration site during June and July 2018 was described. This radiometric calibration campaign made use of six radiometric calibration tarps. The synchronous measurements of parameters such as surface reflectance, atmospheric parameters, and diffuse-to-global irradiance ratio were collected at the satellite overpass. The top-of-atmospheric radiance was predicted by radiative transfer model with these synchronous measurements. The linear relationship between DNs of satellite sensor and band-specific top-of-atmospheric spectral radiance was established, and a stable and reliable absolute calibration coefficient of ZY3-02 MUX was determined in this campaign. We compared the calibration results of the irradiance-based method with those of the reflectance-based method. The results suggested that the irradiance-based method is better than reflectance-based method.

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Sum, Stephen T., and Steven D. Brown. "Standardization of Fiber-Optic Probes for Near-Infrared Multivariate Calibrations." Applied Spectroscopy 52, no. 6 (June 1998): 869–77. http://dx.doi.org/10.1366/0003702981944418.

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The standardization of Fourier transform near-infrared (FT-NIR) spectrometers equipped with fiber-optic probes was investigated. FT-NIR spectra of caustic brines for an industrial process were measured on two different instruments. Calibration transfer across the instruments and probes was studied by employing calibration models built on one instrument to predict properties from spectra measured on the other. The transfer was examined by using spectra without and with preprocessing. The preprocessing methods included a Savitzky–Golay (SG) derivative polynomial filter, a procedure based on a finite impulse response (FIR) filter, and a combination of both. In addition to being a preprocessing technique, the FIR filter is also a standardization method that transforms the instrument response function of one instrument to match that of another. The transformation is performed over a moving processing window without the use of transfer standards. In this study, application of the FIR filter to first-derivative spectra provided the best multivariate calibration models and led to the successful transfer of calibration across different probes and spectrometers.

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Chen, Chi-Shi, Chris W. Brown, and Su-Chin Lo. "Calibration Transfer from Sample Cell to Fiber-Optic Probe." Applied Spectroscopy 51, no. 5 (May 1997): 744–48. http://dx.doi.org/10.1366/0003702971940927.

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A calibration transfer method, piecewise direct standardization (PDS), was applied to a set of two-component samples measured on the same UV-visible spectrometer with the use of a cuvette cell with a 10-mm pathlength and a fiber-optic probe with a 2-mm pathlength. Piecewise direct standardization proceeds by determining a structured transformation matrix using the spectra of a few samples measured with both devices. This transformation matrix can then be used to transform any spectrum measured on one device to that obtained on another device, thereby making the calibration model transferable between devices. We used the spectra measured in a cuvette as the standard set and transferred the calibration model obtained for these spectra to spectra measured with a 2-mm fiber-optic probe on the same instrument. The total standard error of prediction (SEP) for the fiber-optic probe was 5.84 before the calibration transfer and 1.87 afterwards. Spectra were also processed by taking the Fourier transform prior to the calibration transfer. The 512 data points in each spectrum were compressed to 32 terms, starting with the first term after the dc offset. This processing reduced the background and the noise. As a consequence, in the Fourier domain, the total SEP was 5.69 before the calibration standardization and 0.79 after the calibration standardization. A calibration transfer was also performed between two fiber-optic probes; the total SEP in the spectral domain was 2.16 prior to the transfer and 1.04 after the transfer, whereas in the Fourier domain the SEP was 1.50 prior to the transfer and 0.77 after the transfer.

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Journal articles on the topic 'Calibration transfer method'

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