| 摘要 |
<p>A high aperture finite conjugate lens system has a high numerical aperture on both object and image sides of the lens system. The lens system comprises an aperture stop located approximately as the center of the system and a plurality of lens elements centered on an optical axis and arranged into two lens groups of positive power to provide the high numerical apertures on both the object and the image sides of the lens system. The two lens groups are located on each side of the aperture stop and each lens group comprises an outer-most lens element and an inner-most lens element. The inner lens elements are located in close proximity to the aperture stop and each of the inner-most lens elements have a convex surface facing towards the aperture stop. It is also an object of the invention to provide a printer, for example, a laser thermal printer, using such a lens system.</p> |
