斜程大气湍流中成像系统分辨率的影响因素研究
Effects factors of imaging system resolution in slant atmospheric turbulence
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摘要: 大气湍流是影响光学成像系统分辨率不可避免的因素之一。为了研究大气湍流内外尺度、湍流轮廓线及探测高度对光学成像系统分辨率的影响,根据光学成像系统积分分辨率理论及修正Von Karman湍流谱,推导了斜程传输路径下考虑湍流内、外尺度的光学成像系统的分辨率积分公式。数值计算中应用ITU-R公布的随高度变化的大气折射率结构常数模型,结果表明:湍流内尺度对光学成像系统分辨率的影响要远小于湍流外尺度对分辨率的影响,而湍流内尺度又限制着外尺度对光学成像系统分辨率的影响;斜程传输时,湍流轮廓线的影响大于外尺度对积分分辨率的影响;光学成像系统分辨率在近地面受近地面大气结构常数的影响大,而当高度大于5 000 m时,光学成像系统分辨率受风速的影响大。Abstract: Atmospheric turbulence is one of the inevitable influence factor of resolution of optical imaging system. In order to research the effect of inner scale, outer scale, turbulent contour lines and height on resolution of optical imaging system, the optical resolution of optical imaging system considering inner and outer scale of slant atmospheric turbulence was derived, according to the optical imaging system integral resolution theory and modified Von Karman turbulence spectrum. ITU-R atmospheric turbulence structure constant model changing with height was used in numerical calculation. The results show that the effect of inner scale of turbulence on optical resolution is much less than that of outer scale of turbulence; the changes of inner scale will limit the effect of outer scale of turbulence on optical resolution; in slant transmission, turbulent contour lines has more influence than the effect of outer scale of turbulence; atmospheric structure constant near the ground will affect the optical resolution of optical imaging system mainly in the low height; the wind speed will be the major influence factor when the height beyond 5 000 m.