Calibration radiometrics

Recognising the importance of long term calibration and validation of space based instrumentation, NASA developed the SSBUV (Shuttle SBUV), which flew 8 times on the shuttle to calibrate radiometrically the BUV instruments (Hilsenrath et al., 1988 1996). The attention paid to the detail of the calibration of the NASA and NOAA BUV instruments has established the high quality of these data sets (Hilsenrath et al., 1995). 

Blackbody Calibration Radiometric calibration is different from conventional calibration of micrometers and scales. We discuss the radiometric calibration problem in Section 9.6. For now, we discuss the emissivity and the more mechanical parts of blackbody calibration, determination (in a traceable way) of the temperature, and (for cavity type blackbodies) the aperture diameter. 

Documentation of radiometric calibration procedure from historical time until recent was discussed reviewed and documented. The results of parameters and software used in the past were verified by reproducing results. 

In principle, there are two ways to achieve the radiometric calibration of an instrument measuring solar radiation. The first is by comparison to a standard radiation source of known output and the second by comparison to a prototype standard instrument that is capable in measuring the same radiometric quantity. The fist can be applied to broadband detectors only if their spectral response over the whole range of the radiation source is known with sufficient accuracy. The second method requires that the standard instrument has exactly the same spectral response, which is rather unlikely to occur. 

Following the determination of the radiometric calibration of a detector, an additional step is required to achieve its calibration for the erythema response (CIE). Due to manufacturing limitations, the spectral sensitivity of broadband detectors deviates form the CIE biological action spectrum. Therefore, die requirement for a correction factor to enable the simulation of the CIE weighted irradiance by any of those commercial... 

Currently one issue, limiting the exploitation of the retrieval of ozone profiles from the GOME data set is the presence of systematic radiometric calibration errors, which have been identified but not yet eliminated from the operational geophysical irradiance and radiance data products. Some schemes have been developed, which... 

The name quantum detector is given to a radiometric detector having equal or near equal response over the entire range to be measured, UV or VIS and calibrated in quantum units. As is the case for all meters, they may be calibrated for any... 

A radiometer is an electronic measuring device which when coupled to a proper sensing device, e.g., flat response radiometric detectors (quantum) and calibrated, measures most accurately the quantity of incident radiation falling on its sensor. These instruments are available for both the UV or VIS ranges. 

CIE Publication 53-1982 (Methods of characterizing the performance of radiometers and photometers) and CIE Publication 69-1987 (Methods of characterizing illuminance meters and luminance meters Performance, characteristics and specifications) provide detailed information on this error source and much more. CIE Division 2 TC 2-40 is currently working on an updated revision of these publications. Presently no radiometric applications have reached this level of standardization. However, both the European Thematic Network for UV Measurements (6) and the CIE TC 2-47 (Characterization and calibration methods of UV radiometers), established around 1998, (To prepare a CIE recommendation on methods of... 

In principle, one could calculate an absolute Raman cross section from the response of an instrument calibrated with a standard radiometric source. This approach is difficult but has been used to provide the cross sections in Table 2.2. If the relative response function is calibrated accurately, however, it is much simpler to determine cross sections by comparison to standards. Provided the sample positioning and optics permit quantitative Raman signal reproducibility, cross sections of liquids may be determined by comparing the response-corrected peak area to a band with known absolute cross section, such as the benzene 992 cm band. For response-corrected spectra, the ratio of the peak areas under identical experimental conditions equals the ratio of the absolute cross sections. 

Table 8.6 Different methods that have been used to assess rock varnish chronometry. The refinement of age resolution is either relative, calibrated by independent age control, correlated to discrete events, or numerical based on radiometric measurements...

All radiation measurements have always been carried out and processed on the appropriate international pyrheliometric scale. The instruments are regularly calibrated by comparison with the sun as a source to the national pyrheliometer (AHF of The Eppley) and pyranometer (CM 11 of Kipp and Zonen) standards, participating in the periodically organized international or regional comparisons. They are referred to as the World Radiometric Reference (WRR 1980). 

Typically, Bi is measured in a solid sample as a proxy for For example, airborne radiometric surveys use a gamma spectrometer that is calibrated for The resultant measured concentration of Bi is then converted to effective U concentration (eU). What assumptions make this conversion calculation possible Under what conditions would these assumptions invalid Suppose Rn emanation was very high for a particular soil. How would the measured eU compare to a direct measurement of U in such a sample ... 

The typical radiometric performance of marine radar systems was determined with an end-to-end calibration of the marine radar system described above. The object of this work was to use the performance of this particular low-cost technology to assess the applicability to the detection of slicks at sea. 

Long term electrical, radiometric and geometric stability (wavelength calibration). 

Sensing techniques that are applicable to the measurement of solids concentration can be classified into four groups electrical, attenuation, resonance, and tomographic. The electrical methods utilize the dielectric and electrostatic properties of solids. Typical electrical sensors are capacitive and electrodynamic sensors the capacitive sensors measure the dielectric property of the solids, whereas the electrodynamic sensors detect the static charges that develop because of collisions between particles, impacts between particles and pipe wall, and friction between particles and gas stream. Attenuation methods are used with optical, acoustic, and radiometric sensors. Both optical and acoustic sensors are applicable to relatively low concentrations of solids. Radiometric sensors, in which y-rays or X-rays are used, are expensive and may raise safety concerns. They can, however, offer accurate and absolute measurement of particle velocity and thus can be used as calibration tools for other low-cost sensors such as the capacitive sensor. Resonance and tomographic methods, which are still in developmental stages, will be briefly introduced in Section 6.5. 

Radiometric analysis is sinqjle and rapid. Nevertheless, it is rarely used in analytical routine work, as a large number of multiple-element "instrumental techniques are readily available (though the instruments usually are more expensive). Its most extensive use is for calibration of other techniques, and in analytical comparative techniques (e.g. environmental... 

Internal standard Sometimes standards are not available for all the cosmogenic and SN radionuclides. Therefore, many AMS facilities have embarked on elaborate programs to manufacture their own calibrated standards. In most cases, these materials have been prepared locally with the utmost care using conventional radiometric counting, mass spectrometric methods, and/or standard gravimetric dilution techniques to establish their isotopic ratios. Alternatively, some AMS laboratories have prepared standard materials by series dilutions of primary standards. 

The acoustic pressure can be measured through the effects produced in the propagation liquid, namely (1) heating, measured calorimetrically and (2) the action of radiation pressure, determined by measuring the force exerted on a surface (the radiometric method). While the former allows the measurement of the mechanical power of the vibrating source, the latter is associated with the acoustic power transmitted by the acoustic radiation. The acoustic pressure can also be determined using calibrated hydrophones (the acoustic method). 

Radiometers consists of filters, a sensor (silicon radiation detectors, which are sensitive in the range 200-1100 nm, or vacuum photodiodes with specific photocathode materials) and an input optical attachment such a cosine correction diffuser or fibre optic assembly [1762, 1770]. The current of the sensor is converted to a voltage by the converter module . This output voltage (0-5 V) can monitor the relative intensity of emitted radiation of 0-100%. This value can simply be displayed using an analogue or digital instrument, calibrated in any radiometric and/or photometric units. 

Since it is essential that these densitometric values be radiometrically calibrated, new technologies (such as direct phosphor imaging) are required [20]. We tested the feasibility of sequencing pooled templates by synthesizing an oligonucleotide mixture bearing all possible equimolar mixes of the nucleotides at 11 consecutive positions ... 

Transfer standard - A precision radiometric measurement instrument with NIST traceable calibration used to calibrate radiation reference sources. 

All radiometric devices must convert infrared energy into electrical signals. The fundamental properties of infrared converters, commonly called detectors, are analyzed in Section 5.10. In Section 5.11 the operating principles, noise limitations, and several temperature to voltage conversion mechanisms of thermal detectors are treated. Properties and noise characteristics of quantum detectors are the subject of Section 5.12. In many cases radiometric instruments must be calibrated in intensity and wavenumber. For best results calibration techniques are part of the instrument design. Several calibration methods are treated and their merits discussed in Section 5.13. Finally, Section 5.14 deals with considerations encountered in the... 

The main thrust of the calibration of radiometric instruments concerns the establishment of an absolute intensity scale. However, generation of a trustworthy wavenumber or wavelength scale must not be overlooked. Clearly, in the identification of an unknown spectral feature an accurate knowledge of the wavenumber is crucial. Without a good wavenumber scale the identifications of the nitrile, hydrocarbon, and carbon dioxide features discovered in the Titan spectrum would have been difficult (see Section 6.4). 

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