Realization of photometric base unit of candela traceable to cryogenic radiometer at UME

Estimation of Calibration Uncertainties in the Detector-Based Photometric Calibrations

“…The new traceability chain in photometric measurements has been established at UME by realization of SI-based unit of candela with characterized filter radiometers traceable to UME primary-level cryogenic radiometer with expanded uncertainty of 0.30% (k = 2) [5].…”

“…The LUC was operated at color temperature of ≈ 2856 K. The operating current required to obtain 2856 K had been determined by measuring the spectral irradiance of the lamp using a filter radiometer and a set of band-pass filters [5]. Then the RP was glided to a distance d (m) from the LUC and the luminous intensity of the LUC (I LUC ) was calculated from the generated photocurrent P c (A) and the illuminance responsivity of the RP (s v , A/lx) according to the following equation: Fig.…”

“…The operating current required to achieve the color temperature of lamp at 2856 K had been determined as 5.8472 A±0.0006 A (coverage factor k = 1) by repeated measurements of the spectral irradiance of the lamp [5]. The operating current of the LUC was monitored via the voltage drop across a reference shunt resistor (Guildline -0.1 Ω) using a HP-3456 model as DVM.…”

“…The photometer head had been calibrated using new detector-based UME illuminance scale with expanded uncertainty of 0.30% (k = 2) [5,6]. Thus, the standard uncertainty in the illuminance responsivity value was estimated as u(s v ) = 0.019 nA/lx.…”

“…The illuminance responsivity (s v ) of the CPH is s v = 1.8300 nA/lx and it had been calibrated using new detector--based UME illuminance scale with expanded uncertainty of 0.30% (k = 2) [5].…”