Patent ID: 8870400

Claim:
An optical member, comprising: a light-transmissive substrate; an optical pattern formed on the substrate and applying an optical action to light; and a discrimination pattern configured to discriminate between a first position of the substrate and a second position of the substrate reversed from the first position, formed on a surface of the substrate including the optical pattern, and made of a material the same as a material of the optical pattern; wherein the discrimination pattern has a straight-line portion extending along a side of the substrate; the discrimination pattern has a branch portion protruding sideways from the straight-line portion; a plurality of the branch portions is disposed parallel to each other at equal space therebetween; the branch portions are formed so as to be non-line-symmetric with respect to a line passing through the center of the branch portion and being perpendicular to the straight-line portion; and the branch portions are each formed in the shape of a triangle having a first side along the straight-line portion and second and third sides intersecting with the straight-line portion, and the second and third sides being different in length.