Uncertainty analysis of sensor performance parameters in the shortwave infrared spectral range based on nightglow as the main lightsource

Abstract

Images collected in the shortwave infrared (SWIR) spectral range, 1-2.5 μm, are similar to visual (VIS) images and are easier to interpret for a human operator than images collected in the thermal infrared range, >3 μm. The ability of SWIR radiation to penetrate ordinary glass also means that conventional lens materials can be used. The night vision capability of a SWIR camera is however dependent on external light sources. At moonless conditions the dominant natural light source is nightglow, but the intensity is varying, both locally and temporally. These fluctuations are added to variations in other parameters and therefore the real performance of a SWIR camera at moonless conditions can be quite different compared with the expected performance. Collected measured data from the literature on the temporal and local variations of nightglow are presented and the variations of the nightglow intensity and other measured parameters are quantified by computing standard and combined standard uncertainties. The analysis shows that the uncertainty contributions from the nightglow variations are significant. However, nightglow is also found to be a potentially adequate light source for SWIR applications.