## 3 Experimental Setup
### Detector-Level Experiment  
A schematic diagram of the detector-level experiment is shown in Figure 9. The detectors and cold shield were installed on the heat sink covered with an electromagnetic shielding box, and the integrating sphere was observed through the filter and chopper. A Keithley 2614B digital source meter with a measurement accuracy of 100 fA was used to measure the detector response current. The PST of the detector was controlled with a Hamamatsu C1103-05 closed-loop detector temperature controller; its stability was better than 0.1 \({}^{\circ}\)C. The heat sink was installed on the heat exchanger, which connected to the DX-4015 circulating water cooler through a circulating water pipe. The temperature of the key components, such as the filter and the heat sink, was measured to monitor the operational states of the equipment during the experiment. Based on this experimental condition, G\({}_{\text{det}}\)(T) was measured, and a detector-level bench stability experiment was conducted first. To ensure the accuracy of the G\({}_{\text{det}}\)(T), the identified internal and external interference factors in the detector-level experiments were controlled separately. For the internal interference factors such as dark current and background radiation, based on their temperature-related characteristics, a cooling shield was installed in front of the detector window, and a water cooler was connected to the heat exchanger to reduce the background radiation of each component. The dark current was suppressed by reducing PST with C1103-05. With the near-real-time dark reference provided by the chopper, the internal interference factors were removed further. Furthermore, the detector-level experiment faced external interference factors caused by differences in the instrument-level experiments. The factors and corresponding solutions can be divided into the following categories:  
1. The lack of optical-mechanical components results in differences in the spectral response range and the field of view, as well as resulting in more serious stray light interference. In the detector-level experiment, the filter of the same batch used in the PSAC was installed before the cooling shield to ensure a consistent spectral response range. Because of the temperature characteristics of these narrow-channel filters, a transmittance temperature correction experiment was conducted. The field of view of the detector was limited by the cooperation of the cooling shield window and  
Figure 9: Schematic diagram of the detector-level experiment. The SWIR detector assembly was installed on the heat exchanger, which connected to the circulating water cooler through the circulating water pipe. The integrating sphere was observed through the filter and the window of the shielding box with the chopper. electromagnetic shielding box opening. To suppress stray light, a matte flamelette was installed on the interior of the shielding box. 2. The absence of electromagnetic shielding and signal processing components makes it easier to couple the common frequency interference and the noise associated with experimental equipment. For this, a shielding box was tightly connected to the heat exchanger. The detector response current was measured by a digital source table through shielded twisted pairs, and the terminal was wrapped with aluminum foil to reduce electromagnetic coupling. The integration time of the digital source table was set to 50 ms to further reduce the presence of random noise. 3. In the detector-level experiment, the room temperature fluctuations affect the temperature stability of the equipment. Additionally, the heat sink temperature is lower than the ambient laboratory temperature; this may lead to a transmissivity decrease in the optical components due to condensation. To address these issues, an insulating sponge was pasted to the outside of the circulating water pipe to reduce the impact of ambient laboratory temperature fluctuation.