PROJECTION LENS OF OPTICAL SYSTEM FOR IMPROVING CONTRAST RATIO AND EFFICIENCY OF THE OPTICAL SYSTEM

摘要

PURPOSE: A projection lens of an optical system is provided to improve the contrast ratio of the optical system by setting an aperture on a light incident face of the projection lens and increase efficiency of the optical system by preventing the flare effect. CONSTITUTION: A projection lens(8) has an aperture(16) set on a light incident face. The aperture has a ring shape and is detachably attached to the projection lens. A combining member is disposed at one side of the aperture ring. The combining member includes a hook at one side thereof.