Lens array, light emitting diode head, exposure device, image forming apparatus, and image reading apparatus

A lens array comprising:

• a plurality of lens assembly members, each of said lens assembly members including a plurality of lenses arranged therein, said lens assembly members being arranged so that an optical axis of each of the lenses of one of the lens assembly members is aligned with an optical axis of each of the lenses of another of the lens assembly members, said lenses of each of the lens assembly members being arranged in at least one row extending in a direction perpendicular to the optical axes;
• and
• a light blocking member including a plurality of apertures arranged therein, said light blocking member being arranged so that the optical axis of each of the lenses passes through each of the apertures,
• wherein said lens assembly members and said light blocking member are arranged so that the following relationship is satisfied:
• P
• 2
• ≤
• RY
• ⁢
• LO
• -
• F
• F
• where P is a pitch of the lenses, F is a focal length of each of the lenses, LO is a distance between an object surface and each of the lenses, and RA is a distance between the optical axis and an inner surface of the aperture.