Seeker head geometric parameters influence on the hypersonic aero-optical effect

The aero-optical effect of hypersonic flight vehicles creates serious distortion on the imaging system. In this paper, based on the 2D model of a typical optical seeker, flow field density data are obtained by numerical simulation with different optical seeker head radii, cone angles, and relative positions of incident rays reaching the window as variables. Through a series of evaluation parameters, the aero-optical effect under different conditions is quantitatively computed by a ray tracing method. The results show that with the increase of the line of sight (LOS) angle, image deviation decreases. When the optical seeker radius is 40 mm and the cone angle is more than 20°, image deviation will not change with the increase of the cone angle. In the case of a small cone angle, the bore sight error (BSE) decreases gradually with the increase of LOS angle. The BSE decreases with the increase of the cone angle, and tends to be stable when the cone angle is above 40°. The variation of the optical path difference with respect to the flow field density is more sensitive than the distance from the shock wave region to the optical seeker window. The Strehl ratio decreases with the increase of the optical seeker cone angle, indicating that the larger the cone angle, the worse the imaging quality.