Luminaire with improved light utilization efficiency

Abstract

A lens array C has convex lenses and C arranged in alternate and staggering manner to one another. In combination with a condenser lens , the convex lenses form images of respective convex lenses of a lens array on a plane to be illuminated in overlapping so that an illuminance distribution on the plane is almost uniform, while the convex lenses C whose focal length is longer than that of the convex lenses make on the plane an illuminance distribution of a mountain-shape. Flat plate portions and concave lenses may be employed instead of the convex lenses C. A polarization conversion element comprises two elements and an element disposed therebetween with its longitudinal direction being perpendicular to the two element. The images of a light emitting part are included in band-shaped useful incident areas. A polarization conversion section comprises a middle part which is thin but has a larger divergent angle and side parts each has a smaller divergent angle and a simpler construction but is thicker with its size larger.