Diffusion plate, method of manufacturing diffusion plate, and projection device

Abstract

A diffusion plate includes: a glass substrate having a first main surface and a second main surface opposite to the first main surface; and a lens array formed on the first main surface of the glass substrate, wherein, when the first main surface of the glass substrate is viewed in a plan view, the glass substrate and the lens array each have a donut shape, the lens array includes a plurality of lenses, and the first main surface of the glass substrate has an annular first flat surface having a width equal to or more than 1.0 mm between an inner periphery of the glass substrate and an inner periphery of the lens array, or has an annular second flat surface having a width equal to or more than 1.0 mm between an outer periphery of the glass substrate and an outer periphery of the lens array.

Dependencies are inferred from the claim text.