Diffusion plate, display device, projection device, lighting device, and remote sensing light source

Abstract

Spectral noise produced by a diffraction phenomenon of a periodic structure can be reduced to improve homogeneity of intensity of straight diffusion light, and noise of zero-order diffraction light is reduced to improve light distribution properties as well. A diffusion plateof a microlens array type that emits straight diffusion light includes a base material, and a plurality of cylindrical lensesarranged in an X direction on an X-Y plane of the base materialand composed of elongated convex portions or elongated concave portions extending in a Y direction. An aperture width D and a radius of curvature R in the X direction of each of the cylindrical lensesare randomly varied within variation ranges defined by variation full width rates δD and δR, respectively, using a reference aperture width Dk and a reference radius of curvature Rk as references, and an off-center amount Ec of each of the cylindrical lensesis randomly vaned within a variation range defined by a variation full width rate δEc, where δD, δR, and δEc satisfy Expression (1), and at least either δD or δR is not 0%.