Optical body, diffuser plate, display device, projection device, and lighting device

An optical body including a single non-periodic structure region or a collection of a plurality of non-periodic structure regions, the non-periodic structure region being composed of a single lens group including a plurality of single lenses, wherein

• in the non-periodic structure region, a located state of the single lens group is non-periodic as a whole, and
• a ratio of a size of the non-periodic structure region to an average aperture diameter of the single lenses in the non-periodic structure region is more than or equal to 25, wherein
• in the non-periodic structure region, a changing rate, from a reference, of at least one of a located pitch of the single lens group, an aperture diameter of the single lenses, a radius of curvature of the single lenses, and a shape of the single lenses is more than or equal to 5%.