干旱区生态环境知识资源中心

Using the brightness function imaging approach we analyze the impact of the desert and ocean type inverse temperature layer (ITL) on the modulation transfer function (MFT) of an incoherent imaging system. It is shown that an ITL located in vicinity of an imaging path can result in nonlinear deviation in imaging of an object spatial spectrum. Using periodical (sine) patterns of different spatial frequencies as an object, we show that presence of an ITL leads to formation of images with a broadened spatial spectrum with shifted frequency of the sine pattern image in respect to object frequency. The image spectrum shift and width depend on the ITL characteristics and its location in respect to optical wave propagation path. The observed changes in the sine pattern spectral content represent a challenge for analysis of imaging systems performance using conventional MTF based framework. We also analyzed impact of atmospheric turbulence on imaging of periodical (sine) patterns and compared this with the known theoretical results.