OPTICAL PROJECTION APPARATUS AND METHOD

Certain optical imaging systems exhibit disparate vertical and horizontal image focal surfaces; at least one of which is tipped with respect to the optical axis. The projection optics which illuminates such systems must provide that the vertical image components focus upon the nominal vertical image surface, while the horizontal image components focus on the disparate horizontal image surface. Because at least one of these image surfaces may be tilted with respect to the projection axis, correction is required to maintain focus over the entire image surfaces and to eliminate keystoning. The system may also require differing vertical and horizontal image magnifications as projected upon the above disparate focal surfaces. This invention describes, inter alia, the techniques for meeting these varied requirements; to project a rectilinear object field such that it forms a final focused rectilinear image in a system having tipped and disparate image planes.