Research on testing of active and passive HgCdTe APD detector in linear mode

The mercury cadmium telluride avalanche photodiode (HgCdTe APD) detector can simultaneously obtain the intensity information and time information of the target object in the active and passive mode, to realize real-time three-dimensional detection. The testing method of high-resolution time calibration is the basis for verifying three-dimensional ranging. The advantages and disadvantages of Geiger mode and linear mode were analyzed. Besides, the readout circuit structure of a linear mode active and passive HgCdTe APD detector was analyzed, and the time-to-flight (TOF) calculation method was studied. On this basis, a set of high-precision time calibration test platform was built, the system and environmental noise were tested, and the time jitter caused by the noise was 179 ps. The fixed time delay caused by the test instrument was calibrated, and theoretical analysis was conducted on the voltage, capacitance, the accuracy of the ramp generator and the high-precision voltage source and other parameters that affected the TOF resolution. The active and passive information test of the linear mode HgCdTe APD detector was completed at 77 K. The test results show that the circuit linearity is as high as 99.9% at low temperature, the saturation charge capacity is 7 Me−, the root mean square (RMS) value of the time resolution jitters is 2.107 ns. It proves that the test platform and method can effectively evaluate the performance of the detector, and provide reference for precise infrared detection.