On estimating the uncertainty of measurement of a photometer circuit

In this paper, the uncertainty of measurement of a robust photometer circuit (RPC) was estimated. Here, the RPC was considered as a measurement system, having input quantities that were inexactly known, and output quantities that consequently were also inexactly known. The input quantities represented information obtained from specifications of manufacturers, calibration certificates and tabulated data, and the output quantities represented the measurands. In this paper, the extent and nature of the knowledge of the mesurands given the linear model of the RPC, including knowledge of the model input quantities to account for the nature of their inexactness, was quantified. The input quantities were the electronic components of the RPC, the parameters of the model of the photodiode and its sensitivity at 670 nm. Also, the measurands were the coefficients of both the numerator and the denominator of the closed-loop transfer function of the RPC, and the magnitude and phase of the response of the RPC versus frequency. The experimental results were satisfactory.