Abstract：The nonlinearity in the spectral response of silicon detectors is one of the major contributors to the uncertainty in replicating and disseminating the International Temperature Scale and thermodynamic temperature measurements through radiometry, particularly in high-temperature regimes. This nonlinearity primarily emanates from the nonlinear characteristics of photodetectors and associated amplification circuits. The 0.9μm wavelength range is among the primary operational bands for high-temperature standard photometry and thermodynamic temperature measurements in China, underscoring the critical importance of researching the nonlinearity of filter radiometers operating within this spectral band. Utilizing a dual-beam light flux amplification method with a single-phase coherent light source and controlling the light flux via dual ultraviolet fused silica beam splitters, the experiment minimizes uncertainties arising from multiple reflections during light flux control. The experiment characterizes the nonlinearity of the 0.9μm filter radiometer within the photocurrent range of (1.6×10^（-6）~8×10^（-6）) A. The nonlinearity values for individual measurements fall within the range of (-8.7×10^（-5）~4.8×10^（-5）), with standard measurement uncertainties exceeding 3.7×10^（-4） for single measurements. The cumulative nonlinearity value over multiple measurements is -2.7×10^（-4）, with standard uncertainties better than 7.6×10^（-4）.
2024, Vol. 45 
