Fly's eye lens unit for illumination system

摘要

An illumination system includes a light source, an ellipsoidal mirror for converging light emitted from the light source, a fly's eye lens unit disposed at a converging point of the ellipsoidal mirror, a collimation lens for collimating light rays exited from the fly eye lens unit, and an object disposed along the optical path of the illumination system. The fly's eye lens unit includes a first and a second frame defining an incident aperture and an exit one, a plurality of element lenses aligned in a matrix of rows closely in contact with each other, side walls disposed between the first and second frames for housing the element lenses therein, and biasing element for applying a biasing force to the element lenses sideward with respect to the rows of matrix. The respective element lenses are fixedly held without any medium therebetween.