Fig. 1. Variation of gain and excess noise factor of the HgCdTe APD with bias

Fig. 2. Gain grayscale map of HgCdTe APD focal plane at −8.6 V

Fig. 3. Excess noise factor histogram of APD focal plane at M=166

Fig. 4. Variation of NEPh with bias under different integration time

Fig. 5. Schematic diagram of the noise of a APD device versus its gain

Fig. 6. Variation of excess noise factor of semiconductor APD devices with gain^[17]

Fig. 7. Schematic diagram of the thermal imaging/laser gating combined imaging system

Fig. 8. Infrared passive and active laser combined imaging system with one detector

Fig. 9. Images acquired by a dual-mode camera

Fig. 10. Schematic diagram of readout circuit for 3D imaging

Fig. 11. Schematic diagram of an active imaging system witha APD device

Fig. 12. Variation of photocurrent with distance without APD gain

Fig. 13. Passive mid-band infrared images obtained by Sofradir using a 320×256 (pixel spacing 30 μm) HgCdTe APD device. （a） Routine imaging，SNR=61 dB; (b) Image with short integration time, SNR=39 dB; (c) Image with high gain and short integration time, SNR=42 dB

Fig. 14. Dark current variation of HgCdTe APD with bias

Fig. 15. Passive mid-wave infrared images obtained under different gains by HgCdTe-APD. （a） M=1, the integration time is 800 μs;（b） M=1, the integration time is 20 μs; （c） M=19, the integration time is 20 μs