## 4 Results and Discussion
### Detector-Level Experiment Results
#### 4.2.3 Independent Detector Responsivity Temperature Dependence Experiment Results  
In the sub-experiment with four heat sink cooling temperatures, detector response currents for the same light source were measured as the PST varied. The current results before and after filter transmittance temperature correction are shown in Figure 14. The experimental results show that the response currents of the detectors were positively related to the PST, and the relative change trend remained basically constant at different heat sink temperatures. This meant that the variations in the PST of the detector were the main cause of the changes in the responsivity that occurred at the same heat sink temperature. The four response current curves after filter transmittance correction were nearly coincident, which not only verified the validity of the filter transmittance correction process but also confirmed the effectiveness of the approximate real-time dark background provided by the chopper. By averaging the correction results at the same PST, the response currents produced under the heat sink cooling sub-experiment with a filter temperature of 20 \({}^{\circ}\)C were obtained. Combined with the instrument-level sub-experiment without water cooling, the G\({}_{\text{ins}}\)(T) was obtained by cubic spline fitting the response current normalization results with the PST of the detector, and the results are shown in Figure 15. Similar to the instrument-level experiment results, the responsivity change trend is inversely proportional to the PST. This detector-level experiment determined that the responsivity was reduced by approximately 1.5% when the PSAC operated on orbit (T \(\approx\) \(-\)65 \({}^{\circ}\)C) compared with the laboratory-based radiometric test (T \(\approx\) \(-\)30 \({}^{\circ}\)C), with around 35 \({}^{\circ}\)C PST difference. Figure 14: Detector response current temperature curves at four heat sink temperatures: (**a**) before F\({}_{\text{fil}}\)(t) correction; (**b**) after F\({}_{\text{fil}}\)(t) correction. Figure 15: Experimental results of G\({}_{\text{det}}\)(T). This detector-level experiment determined that the responsivity was reduced by approximately 1.5% when the PSAC operated on orbit (T\(\approx\)\(-\)65 \({}^{\circ}\)C) compared with the laboratory-based radiometric test (T \(\approx\)\(-\)30 \({}^{\circ}\)C), with around 35 \({}^{\circ}\)C PST difference. The error sources of detector-level experiments were analyzed to determine their impact on the measurement of G\({}_{\rm det}\)(T) and F\({}_{\rm fil}\)(t). The random errors include the instability of light source radiance, stray light in the laboratory, common frequency interference and noise, temperature instability of detector photosensitive surface and filter, and nonlinearity and instability of detector radiation response. The stability of the integrating sphere radiance was greater than 2%/h. The results of the detector-level bench stability experiment have shown that temperature fluctuation and common frequency interference are effectively suppressed. The response linearity of the detector is about 100% according to the report provided by the manufacturer. Similar to the instrument-level test, the chopper may cause system error in the detector-level test, and its influence is also limited. With multiple measurements and normalizing fitting, the influence of these errors on G\({}_{\rm det}\)(T) and F\({}_{\rm fil}\)(t) measurement is further limited, ensuring the accuracy of the detector-level experiment. To further verify the effectiveness of the condition control measures and dark count subtraction methods used in the detector-level experiment with large temperature ranges of the heat sink, the normalized results of the responsivity temperature dependence curves measured in two detector-level sub-experiments with different heat sink cooling conditions were compared.