Approximation of a melting plateau of large area HTFP cells used for
				spectral irradiance realization

Xie, Yihang; Dai, Caihong; Wang, Yanfei; Wu, Zhifeng; Li, Ling; Khlevnoy, B. B.; Grigoryeva, Irina; He, Shaoming; Lin, Yandong

doi:10.1364/ao.409631

Cited by 1 publication

(3 citation statements)

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“…When the second melting plateau appeared, the optical platform was moved quickly to the position of the spectral comparator to measure the signal of the HTFP at several wavelengths. When the measurement was completed, the optical platform was quickly moved back to the position of the pyrometer to monitor the end of the melting curve [20,22]. Because of limited number of spectral point could be measure by a comparator during one melting plateau, a few melt/freeze cycles were done to cover the whole spectral range from 250 nm to 2500 nm.…”

Section: Measurement Proceduresmentioning

confidence: 99%

“…The Akima fitting method was used to restore the missing part of the melting plateau curve [22]. Figure 6 shows the fitting result: the measured data at the beginning and the end of the melting plateau, and the central recovered data by using the Akima fitting method.…”

Section: Fitting and Correcting Of Melting Plateaumentioning

confidence: 99%

“…Based on the large area WC-C HTFP, NIM put forwarded a method for spectral irradiance measurement of the FEL lamp in the wavelength from 450 nm to 1000 nm [20]. Subsequently, in order to improve the measurement uncertainty of spectral irradiance measurement, NIM proposed a selective multiple fit method suitable to calculate the point of infection (POI) of large area HTFP [21], and then adopted Akima fitting method to recover the missing part of the melting plateau curve during spectral irradiance measurement [22]. In 2020, based on the large area HTFP, NIM completed the spectral irradiance scale realization in ultraviolet wavelength from 250 nm to 400 nm and in near infrared wavelength from 1100 nm to 2500 nm.…”

Section: Introductionmentioning

confidence: 99%

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Spectral irradiance scale realization and uncertainty analysis based on a 14 mm diameter WC–C fixed point blackbody from 250 nm to 2500 nm

Dai

Wang

et al. 2022

Metrologia

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Spectral irradiance scale in the wavelength range from 250 nm to 2500 nm was realized at National Institute of Metrology (NIM) on the basis of a large area tungsten carbide–carbon (WC-C) high temperature fixed point blackbody, which is composed of a 14 mm diameter WC-C fixed point cell and a variable temperature blackbody BB3500MP as a furnace. A series of 1000 W FEL tungsten halogen lamps were used as transfer standards. The new spectral irradiance scale was compared with the scale based on a variable-temperature blackbody BB3500M, and the divergence between these two methods varied from -0.66% to 0.79% from 280 nm to 2100 nm. The measurement uncertainty of spectral irradiance scale based on fixed-point blackbody was analyzed, and the expanded uncertainty was estimated as 3.9% at 250 nm, 1.4% at 280 nm, 0.43 % at 400 nm, 0.27% at 800 nm, 0.25% at 1000 nm, 0.62% at 1500 nm, 0.76% at 2000 nm, and 2.4% at 2500 nm respectively. In the range from 300 nm to 1000 nm the fixed-point scale was improved obviously: the uncertainty decreased by more than 25% compared to the uncertainty based on the variable temperature blackbody. Below 300 nm, the uncertainty became higher because the signal to noise ratio was poor. Above 1100 nm, the contribution of temperature measurement to the uncertainty of spectral irradiance decreases, therefore the uncertainties of two methods are almost at the same level. The fixed-point blackbody was also used to realize the correlated colour temperature and distribution temperature of a tungsten filament lamp, the deviation from the variable temperature blackbody method was -0.5 K and -2.9 K, respectively.

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Section: Measurement Proceduresmentioning

confidence: 99%

Section: Fitting and Correcting Of Melting Plateaumentioning

confidence: 99%