| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and a device for improving image quality and correcting aberration in a small real image projection system using an off-axis reflector, a neutral density window and a plane of rotation subjected to aspherical compensation. SOLUTION: The real image projection system includes a single curved surface mirror with two different planes of optical rotation. One out of the two planes of optical rotation is on the convex surface side and the other is on the concave surface side. In an example, the convex surface is a circular conic curved surface with a plane of rotation, which is a spherical or parabolic surface with reflective optical coating. The concave surface is quite similar to that of a Mangin mirror, however, has an aspherical plane of rotation optimized so as to reduce spherical aberration over a broader range distant from an optical axis. Although in the example the Mangin mirror method to use an aspherical concave plane of rotation is preferable in the system, a single aspherical surface is used on the concave surface to selectively reduce aberration. COPYRIGHT: (C)2004,JPO
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