Comprehensive Analysis of Conversion Gain in InGaAs Short-Wave Infrared Camera Based on Photon Transfer Theory

The InGaAs short-wave infrared (SWIR) cameras are now widely used, but there is poor horizontal comparability between cameras. The current test and evaluation of cameras is mainly based on photon transfer theory. The specific test methods are the European Machine Vision Association (EMVA) image sensor and camera characterization test standards, and the camera test protocol of Teledyne Photometrics (TP). Among them, the conversion gainK(e-/DN) is a key parameter for uniformly quantifying the performance of SWIR cameras. In practical applications, a single test method is prone to deviations and fails to provide a comprehensive analysis of the error sources. In this paper, we compare the theoretical foundations and experimental results of the EMVA and TP testing standards. By plotting the complete noise photon transfer curve, the mean-variance photon transfer curve, and the conversion gain curve, we conduct a comprehensive analysis of the noise and gain characteristics of the SWIR camera. Furthermore, we find that under non-ideal conditions and high read noise, the results obtained from the two testing methods can validate each other, thereby determining the true conversion gain of the camera. This work contributes significantly to the in-depth understanding of camera testing standards and provides valuable insights for evaluating the performance of SWIR cameras.