| 摘要 |
<p>A zoom projection lens system is provided for use with a predetermined illumination means, the system forming a well-corrected, real image of an object and having an entrance pupil. The system comprises at least two lens units each comprising at least one lens element, the lens units being separated by at least one axial space and including a lens unit nearest the image which has a lens element nearest the image, and zoom means for varying the system's effective focal length between a maximum and a minimum value by changing the at least one axial space The system has a Q-value greater than about 1.0, where the Q-value is defined by: <MATH> and where EFLmax is the maximum value of the system's effective focal length, THETA is the semi-angular coverage in degrees at the system's minimum effective focal length, CA is the clear aperture of the lens element nearest the image, f/no is the distance from the object to the system's entrance pupil divided by the diameter of the entrance pupils located a finite distance from the object and f/no is one over two times the numerical aperture determined by the illumination means for entrance pupils located an infinite distance from the object, and L is the number of lens elements in the system which have optical power or correct aberrations. <IMAGE></p> |
