针对极坐标式直接稳像平台结构和间接稳像平台的四反射镜成像光路结构, 推导其两框架运动所引起的像旋角度。结果表明俯仰框和滚转框的运动均会引起像旋。四反射镜间接稳像结构像旋随着离轴角增大, 滚转框运动所引起的像旋角度也逐渐增加, 在小离轴角时, 滚转所引起的像旋也较小。直接稳像结构像旋角度与滚转框架角的正切值成正比, 与俯仰框架角的余弦值成反比。仿真结果表明, 四反射镜结构像旋比直接稳像结构的要小, 对成像质量影响小。

The angle of the image rotation was studied which was caused by the movements of two frames of polar coordinates direct stable platform and indirect stable platform with four reflected mirrors. The result shows that both the movements of pitching-frame and rolling-frame cause the image rotation. The angle of image rotation of indirect stable platform which was caused by rolling-frames increased when the abaxial angle increased. When the abaxial angle was small, the angle of image rotation of indirect stable platform which was caused by rolling-frames was also small. The angle of image rotation of direct platform was direct ratio with the tangent of the angle of rolling-frame and was inverse ratio with the cosine of the angle of pitching-frame. The result of simulation shows that the angle of image rotation of indirect stable platform with four reflected mirrors was smaller than the direct stable platform and has lower influence on imaging.