Patent ID: 8118432

Claim:
A lens array element that has a rectangular plate-like external shape, comprising plate surfaces that functions as light transmission surfaces; and a plurality of cellular lenses that are formed on at least one of the plate surfaces, wherein each of end faces of the rectangular plate-like external shape forms an inclined surface that slants inward from one of the plate surfaces toward another of the plate surfaces, a reference surface perpendicular to the plate surface is formed on a part of at least two adjoining end faces among the end faces, a front view shape of the reference surface region arranged side-by-side with the inclined surface of the end face is a trapezoid, an oblique side of the trapezoid is disposed so as to extend from the one of the plate surfaces toward the other of the plate surfaces, and an upper side of the trapezoid is disposed on a side of the other of the plate surfaces.