| 摘要 |
<p>An image optical system comprising a reflecting mirror for focusing incident light from an object to form an image, an aperture stop disposed at the center of curvature of the reflecting mirror, and aberration correcting plate which is disposed near the aperture stop, whose one side is aspherical, and which eleminates the spherical aberration produced by the reflecting mirror, wherin when the aspherical shape of the aberration correcting plate is approximated by a quartic function z=A(y*y*y*y-k*h*h*y*y) where z is the coordinate along the optical axis, y is the coordinate along a line perpendicular to the optical axis, and A is a constant determined by the correction for eliminating the spherical aberration, parameter k is approximately one.</p> |
