Laboratory Calibration Research Articles

Kalman filtering approach to polarimetric calibration of an optical imager

The Mueller matrix of an optical instrument describes the polarimetric effects the instrument will have on the optical observations it makes in terms of the Stokes parameters. The calibration of the instrument relies on a robust characterization of the elements of this matrix. In this paper, we present what we believe is a new technique that uses Kalman filtering to characterize the Mueller matrices of optical instrumentation based on a set of lab calibration measurements. Kalman filtering is a ubiquitous statistical optimizer that works by comparing measurements and a model of the observed physical system to minimize error. Typically, this technique is applied as a filter to refine a set of observations, but it can also be used to retrieve the properties of the physical system that are not directly measured. We demonstrate the use of the Kalman approach to polarimetric calibration through simulation of measurements, where the polarimetric behavior of optical elements is represented by the Mueller matrices of individual components. The elements of these Mueller matrices are then retrieved with the uncertainty estimates using the Kalman filter approach. The results of this simulation are compared to the standard polarimetric calibration technique as a benchmark, demonstrating the superior performance of the Kalman approach. Then, both the Kalman technique and the standard technique are applied to real measurements from a multispectral polarimetric imager used for atmospheric aerosol remote sensing.

LBDNet interlaboratory comparison for the dicentric chromosome assay by digitized image analysis applying weighted robust statistical methods

Purpose This interlaboratory comparison was conducted to evaluate the performance of the Latin-American Biodosimetry Network (LBDNet) in analyzing digitized images for scoring dicentric chromosomes from in vitro irradiated blood samples. The exercise also assessed the use of weighted robust algorithms to compensate the uneven expertise among the participating laboratories. Methods Three sets of coded images obtained through the dicentric chromosome assay from blood samples irradiated at 1.5 Gy (sample A) and 4 Gy (sample B), as well as a non-irradiated whole blood sample (sample C), were shared among LBDNet laboratories. The images were captured using the Metafer4 platform coupled with the AutoCapt module. The laboratories were requested to perform triage scoring, conventional scoring, and dose estimation. The dose estimation was carried out using either their laboratory calibration curve or a common calibration curve. A comparative statistical analysis was conducted using a weighted robust Hampel algorithm and z score to compensate for uneven expertise in dicentric analysis and dose assessment among all laboratories. Results Out of twelve laboratories, one had unsatisfactory estimated doses at 0 Gy, and two had unsatisfactory estimated doses at 1.5 Gy when using their own calibration curve and triage scoring mode. However, all doses were satisfactory at 4 Gy. Six laboratories had estimated doses within 95% uncertainty limits at 0 Gy, seven at 1.5 Gy, and four at 4 Gy. While the mean dose for sample C was significantly biased using robust algorithms, applying weights to compensate for the laboratory’s analysis expertise reduced the bias by half. The bias from delivered doses was only notable for sample C. Using the common calibration curve for dose estimation reduced the standard deviation (s*) estimated by robust methods for all three samples. Conclusions The results underscore the significance of performing interlaboratory comparison exercises that involve digitized and electronically transmitted images, even when analyzing non-irradiated samples. In situations where the participating laboratories possess different levels of proficiency, it may prove essential to employ weighted robust algorithms to achieve precise outcomes.

Analysis of Iron (Fe) Content in Breast Milk of Breastfeeding Mothers with Level Anemia Normal, Mild and Moderate

Aims: The study aimed to determine the level of iron (Fe) in breast milk samples from breastfeeding mothers who were not anemic (normal), had mild anemia, and had moderate anemia. Methodology: This research is descriptive in nature with a cross-sectional research design. The research subjects were 30 breast milk samples from breastfeeding mothers who had babies aged 0-6 months in TTU Regency, East Nusa Tenggara. 10 samples each in the categories of no anemia (normal), mild anemia, and moderate anemia. Analysis of Fe levels in breast milk samples using Atomic Absorption Spectroscopy (SSA) at the Testing, Calibration, and Certification Services Laboratory Unit, Bogor Agricultural Institute. Results: The results of the analysis showed that the average Fe content in breast milk samples from breastfeeding mothers (normal category) was 4.17 mg/L; Fe levels in breast milk samples from breastfeeding mothers (mild anemia category) were 2.01 mg/L; while the Fe level in breast milk samples from breastfeeding mothers (moderate anemia category) was 1.05 mg/L. From the average figures, it can be seen that there is no significant difference in Fe levels between the three breast milk samples, which is confirmed by the distribution of Fe levels for the 30 samples which is not much different, even from the minimum number of Fe levels in breast milk samples from breastfeeding mothers (normal). still found at 1.03 mg/L (almost the same as the minimum Fe level for breast milk samples from breastfeeding mothers (mild anemia), namely 0.70 mg/L. Conclusion: there were no significant differences in Fe levels in breast milk samples from breastfeeding mothers in the categories of no anemia (normal), mild anemia, and moderate anemia. However, it is still recommended that it is very important to ensure sufficient iron in breast milk to help the baby's growth and development.

International comparisons in the field of measurement of specific adsorption of gases and specific surface area of solids: the optimal amount to ensure calibration and measurement capabilities

Indicators of the accuracy of measurements of the most important characteristics of the structure of porous and dispersed materials - specific adsorption of gases, specific surface area, specific pore volume and pore size – are considered. The performance of sorbents, catalysts and membranes in the chemical and petroleum industries, including the purification of substances and materials, depends on the values of these characteristics. It has been established that for mutual recognition of national standards and certificates of calibrations and measurements of porosity characteristics of solid substances performed by national metrological institutes, it is required to organize and successfully participate in three international key comparisons under the auspices of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology of the International Bureau of Weights and Measures. The results of the participation of national metrology institutes and designated organizations of Germany, China, Japan, Brazil, Turkey and Russia in three international key comparisons in the field of measurements of specific adsorption of gases (nitrogen, argon, krypton) and specific surface area of solids (zeolite, silicon oxides and aluminum) are presented. Carrying out the optimal number of comparisons makes it possible to register in the Key Comparison Database of the International Bureau of Weights and Measures the measuring and calibration capabilities of the national metrological institutes of the participating countries for various matrices in a wide range of measurements of specific adsorption of gases 0.001–25 mol/kg and specific surface area of solids 0.1–1500 m2/g. Based on the results of these three international key comparisons, 18 of broad calibration and measurement capabilities of the Russian participant, the D. I. Mendeleev Institute for Metrology, were entered into the Key Comparison Database; two of these items are currently undergoing examination, including reference materials produced by this institute. A comparative analysis of the results of measurements of the specific surface area of solids using nitrogen and krypton as adsorbates was performed. It has been established that the uncertainty of the measurement results of the specific surface area is significantly less in the case of using krypton as an adsorbate with a specific surface area of less than 1 m2/g, which is due to the higher values of the relative pressure of krypton compared to nitrogen. The use of calibration and testing laboratories in Russia of certified reference materials of sorption properties presented in the Key Comparison Database of the International Bureau of Weights and Measures will ensure metrological traceability in the field of measurements of porosity characteristics.

Linking Seismic Measurements to the International System of Units

AbstractThe current state of the art in the calibration of seismometers is given by internal calibration procedures which give only incomplete information about a seismometer’s response and are based on transfer functions supplied by manufacturers. Calibrations traceable to the International System of Units (SI) provide an independent and comprehensible characterization of seismometers. These calibrations take part in a laboratory using an electrodynamic shaker or shake table. To overcome the issue that seismometers placed in seismic stations are not supposed to be moved to a calibration laboratory, novel on-site calibration methods incorporating a reference seismometer were developed. Such a reference is placed near the sensor to be calibrated, and the transfer function of the seismometer under test can be derived based on the output of both sensors.

Transferability and degree of harmonization of an LC-MS based reference measurement procedure for apolipoproteins in a network of calibration laboratories

Transferability and degree of harmonization of an LC-MS based reference measurement procedure for apolipoproteins in a network of calibration laboratories

CPT calibration chamber testing on tailings

The cone penetration test (CPT) is a widely used technique for on-site investigations. In the field, interpretation correlations of CPT can be established using laboratory calibration chamber tests. Empirical and theoretical correlations were developed for clay and sand under undrained and drained conditions, respectively. However, interpreting these results can be more challenging for intermediate soils that exhibit partial drainage during penetration and lie between fully undrained and drained conditions. Tailings, which are the by-products of mining and are often rich in fine particles, are a typical example of such intermediate soils. To gain a deeper understanding of the behavior of the tailings during CPT, a calibration chamber test was performed at a standard rate of 2 cm/s and subsequently at a slow rate of 0.02 cm/s, and the obtained results were analyzed.

Stability Analysis of Feed Gas Based on Pressure using Gas Chromatography at PT Badak NGL

As one of the LNG processing companies in Indonesia, Badak NGL plays an important role in product QA and QC. Laboratory and Environment Control PT Badak NGL obtained ISO 17025 as a testing and calibration laboratory. In clause 7.7 of ISO 17025, stated that each laboratory is required to improve competence, one of which is by holding interlaboratory meetings. Currently, PT Badak NGL is participating in the implementation of the Inter Laboratory Meeting (ILM) in East Kalimantan. In the implementation of the ILM 112th and 113th in 2022, several laboratories provide outlier results in natural gas sample testing. Various factors affect the results of natural gas sample testing, one of them is the sample pressure. This research aims to determine the minimum pressure limit in testing feed gas samples. The test is carried out by designing a series of two cylinders to test the repeatability value. The sampling process is based on GPA 2166 and the measurement of repeatability values is based on GPA 2261. This method is effective for determining the limit of repeatability values as a reference for the minimum sample pressure before being injected into Gas Chromatography.

Spectroflat: A generic spectrum and flat-field calibration library for spectro-polarimetric data

Flat-fielding spectro-polarimetric data with one spatial and one spectral dimension is inherently difficult as the imprint of the spectral lines needs to be separated from other wavelength-dependent instrumental effect (e.g., fringes or prefilter profiles) and wavelength-independent effects (e.g., dust and sensor response). Current approaches for spectrometers are often based on moving the grating or they depend on optical models and/or on lab calibration data. They are also limited to small spectral regions and are instrument-specific. Approaches that would be suitable for polarimeters have not been reported yet. We present an approach that allows for flat-field calibration data to be to obtained for diffraction-grating-based, long-slit spectrographs combined with temporally modulated polarimetry from high-resolution solar telescopes. This approach is based on nominal flat-fielding procedures performed during the instrument's science operations. We performed a precise and field-dependent correction of the spectrographic distortion effect (resulting in curved spectral lines, typically denoted as a "smile" effect) to ensure the orthogonality of the spectral and spatial dimensions. We identified distortions by tracking the position of multiple spectral lines within the full spectral field of view. From the raw modulated flats, we then removed the solar line imprints and derived separate flat-fields for sensor and slit dust features. Optionally, wavelength calibration and continuum correction can be included in this process. We have created generic Python libraries that can be plugged into existing Python-based data reduction pipelines or used as a standalone calibration tool. We show that for spectrographs covering many spectral lines, a correction of the smile distortion based on optical models alone is not sufficient. Our results demonstrate a suppression of fringes, sensor artifacts, and fixed-pattern imprints in demodulated data by one order of magnitude. For intensity images, the photon noise level can be closely attained after calibration. Our correction works across the full spectral range. The algorithm was tested for different wavelength regimes with emission (EUV range) or absorption (near-UV, VIS, IR range) spectra, on data acquired with ground-based (SST/TRIPPLE-SP, GREGOR/GRIS), balloon-borne (SUNRISE-III/SUSI), and space-based (SolO/SPICE) instruments. The data calibrated with our method offer robust and precise inversion results. We have extended existing spectroscopic flat-field techniques to modern instruments with large imaging sensors covering many spectral lines simultaneously, and with polarimetric capabilities, where methods described so far are not adequate. We believe that our method is applicable as a standard calibration approach for most modern high resolution large-FOV, long-slit spectrographs -- both with and without polarimetric capabilities.

SNI ISO/IEC 17025:2017 IMPLEMENTATION IMPACT ON TESTING LABORATORY

<p>A globally recognized standard for ensuring the competence of testing and calibration laboratories is SNI ISO/IEC 17025:2017. Many testing laboratories are currently using SNI ISO/IEC 17025:2017, and many have already received accreditation. The laboratory serves a variety of objectives, which is beneficial to enhancing the lab's performance. A laboratory's performance could be measured by how well it serves its customers and their satisfaction. This study aims to examine the impact of applying SNI ISO/IEC 17025:2017 on the number of services provided and the level of customer satisfaction in laboratories that have been accredited by KAN for the scope of CNC vertical-type milling machines and CNC lathes for position accuracy test, cutting result accuracy test, and circular movement accuracy test. This study uses a qualitative, descriptive research design and conducts elementary analysis to characterize the overall state of the data. Information on the number of services provided and the degree of customer satisfaction during 2016–2021 were compared, allowing for a comparison of the trends in service quantity and customer satisfaction. The findings indicate that the rise in laboratory services is influenced by the implementation of SNI ISO/IEC 17025:2017. Furthermore, as evidenced by a strong customer satisfaction score, the performance of the offered service has no bearing on the quantity of technological services falling under the purview of SNI ISO/IEC 17025:2017 accreditation.</p>

Establishment of beam qualities for medical applications (mammography and CT) in the gamma and X calibration laboratory of CNESTEN according to EN 61267 standards

The present study aimed to validate the different radiodiagnostic beam qualities (RQT, WAH and WAV) by the measurements of the X-ray beams HVL of a HOPEWELL generator, X80-225 kV from a high voltage range of 10 at 200 kV, at CNESTEN Gamma and X Calibration Laboratory. The experiments were carried out using the PTW TN 32005 ionization chamber, established at 100 cm from the center of the X-ray tube and connected to a SUPERMAX electrometer. The HVL values were measured by applying the attenuation law to the flow of Kair air kerma, including their uncertainties. The obtained HVL values were compared with standard values of diagnostic levels. It was observed that the HVL of the present X-ray machine in most qualities are smaller than the standard ones. An approved method (described in the STANDARD EN 61267 and IAEA TECHNICAL REPORTS SERIES n° 457) was applied to determine the amount of additional filtration required to meet the standard values, and by checking their compliance with the maximum absolute deviation. The results indicate the adequacy of the LEGX laboratory for the calibration of the radiation detection instruments used in computed tomography and mammography with an expanded uncertainty in the best measurement capability of ±4 % (k = 2).

Semantic analysis of two-syllabic terms of metrology. Part 2: Risk in measurements and calculations

Prior to the requirement for testing and calibration laboratories to take into account the risk of statistical assumptions, false positive and false negative decisions in international documents, it was found that the methodology of the “Guide to Expressing Measurement Uncertainty” based on the Bayes approach and the Monte Carlo method for calculating probabilistic risk characteristics is not applicable. A later draft revision of the “Manual on the Expression of Measurement Uncertainty” attempted to shift the interpretation of measurement uncertainty from the scattering parameter to the probability distribution. An attempt to contribute to solving the problem of definitional uncertainty in the International Dictionary of Basic and Basic Terms of Metrology was also unsuccessful. In the new version of the dictionary of general statistical terms and probability theory terms, the term measurement uncertainty is excluded, and one of the notes states that “the probability distribution fully describes the probabilistic properties of the uncertainty of the result”. However, due to the new requirements for risk calculations, international documents were urgently put into effect without radical assessments of the inapplicability of the Bayes approach and the Monte Carlo method, the disadvantages were renamed limitations, but there are no specific instructions for calculating risks. Based on the experience of the compositional approach to estimating accuracy, a procedure based on the convolution of probability distributions in the form of a modified reversal formula is recommended, which allows taking into account the definitive uncertainty in the moment approach. It is established that the method of accounting for the definitive uncertainty by convolution of uniform distributions is practically suggested in the text of the “Manual on the expression of measurement uncertainty”, but not used.

The Need and Potential for Import Substitution of Reference Materials in the Russian Federation: Analysis of Data from the Federal Information Fund for Ensuring the Uniformity of Measurements

The deep integration of the Russian economy into the global economy at the turn of the XX–XXI centuries did not bypass the production of reference materials (RM). Domestic testing, verification, and calibration laboratories receive some RMs from abroad. The number of these RMs is an extremely relevant issue at the moment, since the global competition of national economies for the right to dominate their own markets with state-limited borders has intensified.The strategy of the Russian Federation aimed at achieving the maximum level of sovereignty and independence of the national production sector extends to the sphere of metrological support for the activities of business entities. The practical implementation of this strategy requires a comprehensive analysis of the information presented in the Federal Information Fund for Ensuring the Uniformity of Measurements (FIF EUM) on the number of foreign RMs, the scope of their application, and an understanding of the structure of demand for foreign RMs within the country. At the same time, it is necessary to form an idea of the technical capabilities of producing domestic RMs.The article provides solutions to most of the problems stated above. The data presented by the authors can be the basis for making management decisions in the field of production and circulation of metrological support equipment for production.

Comparative analysis and classification of measurement procedures and procedures for transferring of unit of quantity as elements of metrological traceability chain of measurement results

The article analyzes types of measurement procedures and procedures for transferring a unit of quantity, such as: primary reference measurement procedures, reference measurement procedures, calibration procedures, validation procedures, end-user measurement procedures and measurement procedures. The article discusses requirements for developing the presented procedures, their research and approval. The article presents a classification of procedures depending on their place in metrological traceability chain, type of determined metrological characteristics and their application in the field of regulation. Based on the results of the analysis of regulatory documents, a table that describes basic requirements for development and approval of measurement procedures and procedures for transferring a unit of quantity is presented. The article also discusses requirements established for conformity assessment procedures for measurement procedures and procedures for transferring а unit of quantity, such as certification, validation and verification of procedures. The article presents definitions and scope of application for conformity assessment of measurement procedures and procedures for transferring a unit of quantity. Based on the analysis of requirements for conformity assessment of procedures, a flowchart for selecting appropriate conformity assessment procedure is presented. Due to this scheme, laboratories will be able to unambiguously choose one or another conformity assessment procedure to approve the required measurement method or method of transferring a unit of value. In particular, in preparation for accreditation for compliance with the requirements of ISO/IEC 17025-2017 “General requirements for the competence of testing and calibration laboratories.” The proposed scheme of choosing a procedure for conformity assessment of a specific measurement procedure eliminates ambiguity of the requirements of regulatory documents.

AN APPLICATION FOR THE CALIBRATION OF THE TWO-PRESSURE HUMIDITY GENERATOR

Two-pressure humidity generator (2-PHG) has capability to produce environments of known humidity with the “two pressure” method that is proven by NIST. The 2-PHG is supplied with known humidity values, the values can be used for instrument calibration, verification and such as other processes. The set point values can be entered from the device’s front panel by an operator. 2-PHG calculates the relative humidity from the pressure and temperature measurements with the formula. The computer controls the ratios on the formula to generate a known humidity value. 2-PHG has to have traceability for using on calibration processes of other devices; 2-PHG must be calibrated. This study represents an application of the 2-PHG calibration by using the guides and articles in the literature about the device. Calibration of the 2-PHG contains examination of the each parameter of the formula that was given for humidity calculation. Four temperature and two pressure probes that are saturation temperature probe, pre-saturation temperature probe, expansion valve temperature probe, chamber temperature probe, low pressure probe, high pressure probe help 2-PHG to calculate the formula. Calibration of the 2-PHG, also, contains the calibration of the temperature probes and the pressure probes. This study expresses an application of the calibration of a 2-PHG which is located in Turkish Standard Institution Gebze Calibration Laboratories and the uncertainty calculation of this application can be seen on this paper. Each uncertainty parameter of the formula and uncertainty parameters of the probes that are affected to the total uncertainty were calculated. For different temperatures and different relative humidities, the measurement uncertainty of this application was given on this paper. This study can be used as a supplementary document in the calibrations of the 2-PGH and in the new studies.

Stability, homogeneity and measurement uncertainty estimation of PVP-I solutions for the application on oro and nasopharynx against SARS-CoV-2

Aqueous solution containing different concentration (0.5, 0.6 and 1.0%) (w/v) of Polyvinyl pyrrolodon-Iodine (PVP-I) complex, a well-known antiseptic; is prepared and the stability and homogeneity of these solution is assessed as per the ICH Guidelines and International Harmonized Protocol respectively. The solutions were found to be sufficiently homogeneous and stable for a year at 25 °C (60%RH). Measurement uncertainty of the prepared PVP-I solutions were estimated by identifying possible sources of uncertainty using Ishikawa diagram and preparing uncertainty budget based on scope of calibration laboratory. The stable and homogenized PVP-I solution is to be used in a clinical trial for the application on oro and nasopharynx against novel SARS-CoV-2 Virus.

Simulations of S waves from the piezoelectric source to the receiver to assist in laboratory measurements of rock properties

An accurate determination of the emitted S-wave arrival time at the piezoelectric receiver of laboratory triaxial cells is challenging due to the complex preceding P- and S-wave patterns. To analyze this pattern and decipher the true arrival time of the emitted S wave, we simulate wave propagation from the actuator to the receiver. The piezoelectric response is accounted for, and the electromechanical coupling is solved, using the spectral finite-element method or approximated using a linear spatial variation of the electric potential over the actuator to capture the same field over the receiver. The fully coupled algorithms are validated with 1D simulations and compared with an exact solution constructed with the method of characteristics. Simulations for a 2D simplified experimental system indicate the validity of the linear simplification. The comparison of the simulated results through a section of the triaxial cell with laboratory calibration data for a steel specimen validates our choice of damping material proxy within the actuator. A final series of simulations for two orthotropic shales with different anisotropy axis orientations with respect to the cell, and two Fontainebleau sandstones with very different [Formula: see text]/[Formula: see text] ratios, is presented. These differences in physical properties have little impact on the wave pattern at and just after the arrival of the main S wave. The pattern is influenced more by the experimental setup geometry and the actuator’s internal structure than by the nature of the specimen.

A bipolar SMPS network for measuring atmospheric aerosols using natural air ions

To study atmospheric aerosols, it is essential to build networks that are continuously monitoring particle number size distribution (PNSD). PNSDs are often measured using electrical mobility spectrometers such as scanning mobility particle sizer (SMPS) which includes a neutralizer that conditions the charge state of particles to the pre-assumed distributions. During long-term atmospheric measurement, the charge state can deviate from these assumed values. Measuring both positively and negatively charged particles using a bipolar SMPS helps to capture the variations in aerosol charge state. In this study, we set up a network of bipolar SMPSs at three urban sites and three suburban sites in six Chinese cities. Removing the conventional neutralizer, the bipolar SMPS utilizes the natural aerosol charging process by atmospheric ions. Newly developed aerosol classifiers and detectors were used. Harmonized quality assurance procedures were adopted to assure the performance and the data quality, including laboratory calibrations and intercomparisons, maintenance and monitoring during field measurements, and data inversion and validation. PNSDs are effectively measured by bipolar SMPSs using natural charging process at all six sites. During six months of field measurement in these sites, ion mobility ratios fluctuate significantly while the daily averaged values are stable around 1.0. Particle number concentrations integrated from PNSDs are consistent with those directly measured by the detectors (within a variation of 10%).

Determination of the overconsolidation ratio and undrained shear strength of cohesive soils by CPTu measurement

Estimations of the undrained shear strength (Su) and overconsolition ratio (OCR) of cohesive soil are essential for the evaluation of geology investigation. In comparison to time-consuming laboratory tests, the field piezocone penetration test (CPTu) can rapidly evaluate these parameters. However, existing studies have mainly relied on empirical correlations to estimate the undrained shear strength Su and OCR from CPTu measurements. These correlations are mainly empirical, involving fixed coefficients multiplied by CPTu measurement. Based on the coupled Eulerian-Lagrangian method, this study employed large deformation finite element modeling to summarize and extend the relationships between CPTu measurement and the estimation of undrained shear strength Su and OCR in cohesive soils. These relationships allow for predictions based on CPTu measurements without the requirement for laboratory calibration or referencing to field benchmarks. The accuracy and applicability of the proposed prediction formulas are validated through field case studies for comparative analysis.

Polarization upgrade of specMACS: calibration and characterization of the 2D RGB polarization-resolving cameras

Abstract. The spectrometer of the Munich Aerosol Cloud Scanner (specMACS) is a high-spatial-resolution hyperspectral and polarized imaging system. It is operated from a nadir-looking perspective aboard the German High Altitude and LOng range (HALO) research aircraft and is mainly used for the remote sensing of clouds. In 2019, its two hyperspectral line cameras, which are sensitive to the wavelength range between 400 and 2500 nm, were complemented by two 2D RGB polarization-resolving cameras. The polarization-resolving cameras have a large field of view and allow for multi-angle polarimetric imaging with high angular and spatial resolution. This paper introduces the polarization-resolving cameras and provides a full characterization and calibration of them. We performed a geometric calibration and georeferencing of the two cameras. In addition, a radiometric calibration using laboratory calibration measurements was carried out. The radiometric calibration includes the characterization of the dark signal, linearity, and noise as well as the measurement of the spectral response functions, a polarization calibration, vignetting correction, and absolute radiometric calibration. With the calibration, georeferenced, absolute calibrated Stokes vectors rotated into the scattering plane can be computed from raw data. We validated the calibration results by comparing observations of the sunglint, which is a known target, with radiative transfer simulations of the sunglint.