| abstract |
The invention consists of a fixed focal length objective lens forming an image of an object with a plurality of lens elements and an aperture stop ( 114 ), wherein the aperture stop ( 114 ) defines an aperture stop proximity space ( 118 ) and at least one field proximity space ( 120, 122 ). The objective lens comprises at least three aspherical surfaces ( 124, 126, 128, 130 ) of a lens element. Either two aspherical surfaces ( 128, 130 ) are positioned in the aperture stop proximity space ( 118 ) and at least one aspherical surface ( 124, 126 ) is positioned in a field proximity space ( 120, 122 ). Or at least one aspherical surface ( 128, 130 ) is positioned in the aperture stop proximity space ( 118 ) and two aspherical surfaces ( 124, 126 ) are positioned in a field proximity space ( 120, 122 ). This distribution of aspherical surfaces provides for means of optimally correction aberrations leading to a very high level of aberration correction. |