In this paper, the infrared radiation characteristics of sea background have been studied. First, MODTRAN4.0 was used to calculate the transmittance of mid-infrared and far-infrared, and the solar spectral irradiance, the atmospheric and sea surface radiation. Secondly, according to the JONSWAP sea spectrum model, the different sea conditions grid model based on gravity wave theory was generated. The spectral scattering of the sun and the atmospheric background radiation was studied. The total infrared radiation of the sea surface was calculated. Finally, the infrared radiation of a piece of sea surface was mapped to each pixel of the detector, and the infrared radiation is simulated. The conclusion is that solar radiance has a great influence on the infrared radiance. When the detector angle is close to the sun’s height angle, there will be bright spots on the sea surface.
This paper gives the preprocessing technique research which includes odd-even calibration, bad pixels compensation and non-uniformity calibration for the high sensitivity push-broom long wave infrared camera. The noise equivalent temperature difference (NETD) of the infrared camera has achieved less than 10 mK. The paper analyzes high sensitive imaging effects by using different preprocessing standards according to the test data, also analyzes the effects on imaging quality when using different preprocessing methods. At last the paper gives the suitable image preprocessing methods for the high sensitive infrared camera: the odd-even calibration method considering velocity to height ratio, the bad pixels compensation methods which are unique for temporal and spatial bad pixels and the non-uniformity calibration methods which combines the calibration based on black body testing data and the calibration based on real scene imaging data. It is validated that the residual nonuniformity of the infrared image can be reduced to 0.03% by using the preprocessing methods, which is satisfied for the requirement of high sensitive imaging.