机载光电平台球罩的视轴指向误差

摘要:机载光电平台光学镜头前的通光窗口,多选用内外球心重合的等厚球形玻璃球罩。球罩在加工过程中产生内外表面球心不重合，会给视轴指向精度带来附加误差。本文根据光路图推导出了产生这种误差的数学表达式，分析了内外球心偏离对视轴指向精度的影响。实验结果表明，实测数据与数学推导结果吻合得很好。当某型号球罩的内外表面球心沿视场中心线的偏离达到0.26mm时,45视场处的视轴指向误差实测值达到0.075,超出了0.029（0.5mrad）的允许值。为了将球罩加工误差带来的视轴指向偏差减小到0.017（0.3mrad），内外球心偏离必须控制在0.10mm以内。

Effect of spherical shell of airborne electro-optical platform on optical axis pointing precision

Abstract: The concentric glass spherical shell with the uniform thickness has been dominantly chosen as the transparent window, in front of the optical lens of airborne opto-electronic platforms. When the centers of spheres on the inside and outside surface have been misaligned during the producing, there exists the additional pointing error. In this paper, the theoretical expression concerning the optical path has been derived. The experimental result indicates that the measurement agrees well with the theoretical result. When the concentric misalignment of the spherical centers is 0.26 mm, the axial pointing error at 45 degree field of view reaches 0.075 degree, much bigger than the limitation which is set as 0.029 degree (0.5 mrad). In order to reduce the pointing error to 0.017 degree (0.3 mrad), the concentric misalignment has been expected under 0.10 mm.